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THE FREE-LIVING UNARMORED
DINOFLAGELLATA

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THE FREE-LIVING UNARMORED
DINOFLAGELLATA

BY

CHARLES ATWOOD KOFOID AND OLIVE SWEZY

MeMOIRS OF THE UNIVERSITY OF CALIFORNIA

VOLUME 5

UNIVERSITY OF CALIFORNIA PRESS
BERKELEY, CALIFORNIA
1921

Memorrs OF THE UNIVERSITY OF CALIFORNIA
Vol. 5, pp. 1-562, 12 plates, 388 figures in text
Issued June 28, 1921

iprefacen sa

Introduction Ree RE TR sn
Materialtandtcollectionst. 2-0. -..cecs ee cesce ee.
Methods...

General morphology =o roe
Size and form Ee ee
Motor organelles .....................

Furrows and torsion of the body...

DS ROTEL LET ences a: os Soe aoe SERBS ORE RU RR EER SAR RR as Stn Ck
FATS GS Beareeet pears es ene ad ate ee ie al aloe

Ocelhiea= Gott ade De satee ae eC Ca EEE ee ee

INGMalocy Sts see eee

Cytoplasmic differentiation
Coloration. Fie Oe
Surface differentiation.

hy SIO] O Gaye eem ee eee ean ee eS
“Red Water’’..
Nutrition ee
Reactions to stimuli.............
Luminescence

Comparative organology....
Ocelli.
Pusules.. wees
INEMAatOCYStS)......-..----

bitercy Clesivsn tees.

Effects of parasitism on life cycle.

Binary and multiple fission
Encystment EELS
Sex

CONTENTS

CHAPTER II

CHAPTER III

CHAPTER IV

CHAPTER V

CHAPTER VI

> OV

Or Or Or Or
“I &D

oOo

iv MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

CHAPTER VII ee

Evolutionary development sa pidavacdas salts Gives sos G0t0SE ok oe ae ee ee ceszet ONG
Relationships ...... scobetsbaiSeieeslecte eed eee eee ee eee 78
Derivation PEA RN Re wh es es» aa Pes RN tcc eI 82
Development within hen CTLOUp eee eee SRR rhe een Perce iO ets ar asare AI 85
Structural evolution oi eg Roe Saas vocdalvs aides cheek EES ee
Nutrition and evolution ecg ihidooscceceates pated awk oon ee Ls Socios kot See OL
Relationsitosthe Meta zona ee eee eee eee bonita ee eee ee ee rs OS:

Distributions -s ee meee? ee Oey Ae ene Le Lee, Soe oe ee eee AOA.
Loeal distribution Nee AICP OO EPO PORTE et AS EE el A hapa ee 99
Historical discussion et ee a SL ee cee insice Skene eee eal (()

CHAPTER Ix

Classification of the Dinoflagellata............. Se ets eo eee Pee tcc entrees nt MG nat ie Pein ah i . 106
Subclass Dinoflagellata Bitschli ee peek 1 bis soot ave See oe eee OG
Key to orders .. ; ce Sete ee eS
Order Iinnfendne Delage and Heronard entanul - ; a psee eae roe ree LOS
Key to the tribes..................... Om Ee ee Be Rae eS cca POS

Tribe 3. Gymnodinioidae Poche Gmende ee oe eae oe ae ee eee 9)
MD ISCUSSIOT 25st cceteses cos cat ese ees ehecees sees cesta Sat ere er ty: er Serre Bly)
Key to families .......... eee roe soy ceer es eee eee 111
Family 1. Protodiniferidae a nov. Sete eee Be de once rca 111

Key to genera eR ee ree re een nadseoninoncces, INP
Protodinifer gen. nov. 2 Be Ste oe ee Sy
Description of species with nope on synonymy, eens aa diesibnnicae siehinene a ee aL
Oxyrrhis Dujardin.......... ecigugent ch isidsts. ES eats Sen ee 5 dG
Discussion......... sees aastitce 2d3 SeREMay 0 aes Dea RCo 116
Description of species (1) soshdacnawsSessasunaceuceseecStcoo: tpn ud Acetic see Soe es nr LEZ)

CHAPTER X
Gymnodiniidae Kofoid ..... : ee ee Pe Pere eee cere eecsanietnesnceice, LIPAD

Discussion............. oi: SPR ST AE? Ne ALS enc ee 20
Key to genera... ae ee Fe hen CON are en Ne Need trie tetany Reeder Asean atic: So
Hemidinium Stein. Souths a ees Lee ee Se I eo 121
Discussion............ ea erate ene a Ree aR Ben Nn or el COR re oht aera mite aroceoce ee done 121
Description of species a, oe toe Be Be Serer ree Bee re en ore ee
Amphidinium Claparéde and Lachmann............ eRe Re eS eee ee Aero cee, |i!
Discussion, history, distribution........ Je RSS ee See tee ee re . 124
Subgenus Amphidinium subgen. nov. eee Pee Nt or Basten Se ee
Subgenus Rotundiniwm subgen. nov. eet ee cea ee eee ee 5 ISH
GY, CO:SPE CIES A 5 1222s sinc csccxheesecors teat Bete ORR oe Ee a nee eee = el

Description of species wiih notes on synonymy, setae and ciapbniion i eee eho hee yg) LS

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA

CHAPTER XI

Gymnodinium Stein emend.
Discussion, history, distribution
Subgenus Gymnodinium subgen. nov.
Subgenus Liniadinium subgen. nov...
Subgenus Pachydiniwm subgenus. nov... ae
Key to species. ; : :

Discussion of species, matt devotion cic , G. abbreviatum to G. grammaticum..................

CHAPTER XII

Species of Gymnodinium (continued) ... ie at
Gymnodinium hamulus sp. nov. to ¢. uae.

CHAPTER XIII

Gyrodinium nom. gen. nov.
Discussion, history, Hiemipations
Subgenus Gyrodinium subgen. nov.
Subgenus Laevigella subgen. nov.............
Key to species... eee Oe erate
Discussion of species ah dezoiation, Bie. Seth ae Pee ee TTT Es Eanes

CHAPTER XIV

Cochlodinium Schiitt
Discussion, history, dlecodtatton
Subgenus Cochlodinium subgen. nov...
Subgenus Polydinium subgen. nov. ....
Key to species... :
Description of species, w Ain discussion, ete...

CHAPTER XV

Torodinium gen. nov.
Discussion, Hevory, distribution.
Key to species
Discussion of species mith cesenmnnion te.

CHAPTER XVI

enna 6k Letalhdlen Vato bey stn tne a0 OK capseccoceacocnoss cn. scroosaeacesorc eeeeeee
Diagnosis................

Polykrikos Biitschli
Discussion, history, distr pation
Key to species... ; eee
Discussion of species with description, ete.

bo

.. 218
. 218

bo
“I “I
do Ww &

vl MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

CHAPTER XVII

Family 4. Noctilucidae Saville-Kent............
Discussion.
Key to genera.
Pavillardia gen. nov...
Discussion
Description of species w sth dReenesiom, CR.
Noctiluca Suriray
Discussion
Description of species, w ith Aecvestion, ete.

CHAPTER XVIII

Family 5. Pouchetiidae fam. nov.
Discussion
Key to genera

Protopsis gen. nov. BN ed
Discussion, history, distribution.................
Key to species

Description of species aah deeeoesitom. cic. eee cee reed
Nematodinium gen. nov. ts ee

Discussion, history, dieniinwdion. eee

Key to species Ee ee eee ¥ uaa

Description of species with dissnesion CU Gee perme ene

CHAPTER XIX

Pouchetia Schiitt emend ..... Pe ee RA ao :
Discussion, history, distribution
Subgenera of Pouchetia

Key to species. Aedrh sn Sobext ensues weet aaet ee eo teste ee eres
Description of species aeib eeussion Cera aes

CHAPTER XX

Proterythropsis gen. nov....... eS ee A Ea ees
Discussion... ss teen aiiie? o/s wicichena oe ae eee
Description of species w ith dgaussion, fie ee eee Siete

Erythropsis Hertwig.............. SER ee Oe Nee ee
Discussion, history, fisuribation TER Re Cee One
Key to Species...... ; Bh AS 5%
Description of species with discussion, ete..........00..00....

Summary........ y ae Se Ie RR NR oc RA 3

Literature Ged. es

igplnmation emits fe sta bday aero Ses tt WR toe, See ee

PREFACE

The collections upon which this study has been based were made off the
coast of southern California, in large part from June to August, 1906, and
from June to September, 1917. Preliminary observations on a number of the
more common and hardier species found in the inshore plankton have been
earried on, mainly during the summer months, over a series of years by the
senior author; in 1901-1903 at the summer Marine Laboratory of the Uni-
versity of California at San Pedro and at Coronado Beach; in 1904-1907 at
the Marine Laboratory of the San Diego Marine Biological Association and
in 1907-1917 at its successor, the Scripps Institution for Biological Research
at La Jolla, and at the Naples Biological Station in January-May, 1908, while
occupying the table of the Smithsonian Institution.

Additional opportunities have been afforded to the senior author in the
Agassiz Expedition to the Eastern Tropical Pacific in 1904-1905, and in the
plankton traverse of the Northern and Western Pacific and Indian oceans
during a trip from San Francisco to Colombo, Ceylon and return in 1916, to
widen his knowledge of the dinoflagellates generally. The immediate results
of these observations are not, however, included in this paper.

The junior author, who has been associated with the enterprise since July,
1915, spent the summer of the two subsequent vears at La Jolla, in work upon
these and other dinoflagellates. In June to September, 1917, the most intensive
work was done upon the naked dinoflagellates. The junior author spent three
months at La Jolla, with Miss Anna L. Hamilton as colorist, and was joined
by the senior author during the six weeks while the material was most abundant.

Much assistance was rendered in the earlier years by Mrs. Effie J. Rigden
Michener, and in the summer of 1914 by Miss Inez Smith, who made a careful
investigation of the dinoflagellate fauna of the beach sands. In the summer
of 1917 Miss Rofena Lewis, Miss Pirie Davidson, Miss R. E. Merrill and Miss
FE. H. Logan gave material assistance in seeking for the elusive organisms and
in preliminary analvyis.

The authors are especially indebted to Miss Anna L. Hamilton, to whose
artistic skill in the use of water colors and faithfulness in interpreting our
analytical sketches, our plates owe whatever technical merit they possess. We
are also indebted to Miss Rofena Lewis for much valuable assistance in the
preparation of the bibliography and much of the clerical work connected with
the preparation of the material.

[vii]

vill MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Most of all, our work owes its origin and continuance to Professor William
E. Ritter, Director of the Scripps Institution, for it was he who encouraged
the beginning of this work many years ago, and has generously fostered its
continuance and completion with the facilities and resources of that institution,
made possible by the generosity and continued interest of its donors, Miss Ellen
S. Scripps and Mr. E. W. Scripps.
CHARLES ATWoop Korom,
OLIVE SWEZzy.

ZOOLOGICAL LABORATORY,
UNIVERSITY OF CALIFORNIA,
BERKELEY, CALIFORNIA.

Transmitted August 30, 1918.

INTRODUCTION

The dinoflagellates form an exceedingly important part of the ocean mead-
ows, the source of the primitive food supply of the sea, both in the number of
individuals and in the total mass of living substances produced. They abound
both in neritic waters and in the high seas and range from the tropics to the
polar oceans. As synthetic producers of carbohydrates, proteins, and fats they
hold high rank among the protists of the sea and of fresh water. In abundance
they are second only to the diatoms in the marine plankton, while locally and
in midsummer they may far outnumber even these abundant organisms. At
their periodic maxima they may surpass the diatoms in the total mass of sub-
stance produed and in the rapidity of their development. These local massive
developments are the primary and all but universal cause of the discolored seas,
and of the phenomenon of the ‘‘Mare Sporco,’’ or luminescent waters, which
are wont to occur in midsummer in neritic regions and on the high seas, espe-
cially in the tropics and along the western shores of the American continents.
Similar extensive growths of fresh-water dinoflagellates, especially of Ceratiwm,
cause reddish discolorations in reservoirs and lakes in midsummer.

The phenomenon of the phosphorescence of the sea has been known since
Pliny (see Bostock and Riley, 1885) noted the fact that ‘‘there are sudden fires
in waters.’’ But the organisms which are responsible for the most of the light
in the ship’s wake and in the breakers along shore have been studied but little,
and the light they shed is often erroneously attributed to the Copepoda or
exclusively to Noctiluca, while in reality it may often be due to other dino-
flagellates.

No monograph on the Dinoflagellata is included in the reports of the Chal-
lenger Expedition, and Pyrocystis, the most brilliant dinoflagellate of the high
seas, was described by Sir John Murray as a diatom. Even our most widely
known Textbook of Zoology (Parker and Haswell) erroneously ascribes to the
neritic genus Noctiluca the phosphorescence of the high seas.

The purpose of this monograph is to set forth a summary of our present
knowledge of the most elusive and least known representatives of the dinofla-
gellates, namely, the naked or unarmored forms. Many of these are most
brilliantly colored, vying with the orchids and butterflies in variety of color
and delicacy of shading, although microscopic in size. They also include some
of the most highly organized and uniquely specialized of the greatly diversified
group of Protozoa, presenting species possessing, among other organs, a struc-
turally complicated eye with lens, pigment mass, and sensory core, also a mobile
tentacle-like structure, and nematocysts not less specialized than those of the
coelenterates. These highly specialized species exist moreover within a group
of protists in which holozoic and holophytic nutrition occur in different species
within the same genus. The great fundamental function of nutrition has not

[1]

bo

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

in the dinoflagellates reached that definite degree of differentiation which de-
limits the animal and vegetable kingdoms. On this basis botanists and zoologists
alike will continue to regard the dinoflagellates as within the legitimate scope
of their several fields. The present paper increases the evidence for a much
greater representation of holozoic forms among the dinoflagellates than has been
hitherto known. Much confusion has accordingly arisen in the study of Dino-
flagellata due to the fact that the group contains both holozoie and holophytic
organisms, with the result that the literature dealing with them has been divided
between the botanical and zoological fields, with a consequent lack of correlation.

Furthermore, the organisms themselves, as shown above, are usually ex-
ceedingly sensitive to adverse conditions on removal from their normal habitat,
do not long survive microscopical examination, and are subject to progressive
changes as dissolution approaches. As a result these pathological conditions
have sometimes appeared in the figures and descriptions as normal phases of
form and function. This is especially true of the delicate, pelagic represent-
atives of this group. It is hoped that the present paper will be of use in clearing
up some of the obscurities which still remain regarding a number of species of
the group.

This monograph also sets forth the authors’ conceptions of the relationships
of the genera within the group, which differ materially in a number of partic-
ulars from those of previous investigators in this field. One feature of some
significance is the re-alignments necessitated by the discovery that Pyrocystis,
at least as originally described by Murray (1876), is only a phase in the life
history of other Dinoflagellata, e.g., Gonyaular, A second feature is the sep-
aration of Noctiluca from the Cystoflagellata Haeckel (1873) and its inclusion
in the Noctiluciidae, merely a family of the order Diniferidea. The gap which
has long separated these from the Dinoflagellata has been so completely bridged
by discoveries, some of them long overlooked, such, for example, as the signifi-
cance of Hertwig’s (1876) Erythropsis, that the isolation of Noctiluca and
related forms in a separate order, or even suborder (Jollos, 1910), is no longer
defensible.

The reasons for the slow development of our knowledge of this remarkable
group of organisms are their eupelagic habitat and the correlated fact that
they are but poorly represented in the neritic plankton. Few marine biolog-
ical stations are so located that they have quick and ready access to the pelagic
life of the open sea, and the fresh-water species of the Gymnodinioidae are
relatively few and show little differentiation. An additional reason lies in the
fact that their period of maximum occurrence is in midsummer and that the
area of greatest abundance is in the warm temperate and, presumably, the
tropical seas. The main reason, however, is to be found in the exceedingly
delicate and sensitive nature of the organisms themselves. The turmoil of the
filtering water in the plankton net, the crowded state of the plankton collection,
and even the conditions of aération on the microscopic slide are all hazardous
in the extreme to the soft and flexible bodies of these dinoflagellates. Mutilated

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 3

individuals of such delicate species as Gymnodinium rubrum were almost as
abundant in our plankton collections as were normal ones.

These species are also noticeably sensitive to illumination and under condi-
tions of microscopical examination undergo cytolysis rather quickly. Some
of the more delicate ones succumb in a few moments after exposure to the
intense illumination of the high-power microscope. Others survive for a longer
time, though rarely for as much as an hour, while in every case the organisms
begin to round up, lose very quickly their characteristic contour, distinctness
of sulcus and girdle, and normal color and distribution of pigment or other
colored substances, in the confinement of the microscope slide. The result is
that as soon as the organisms quiet down sufficiently to permit observation and
analysis of structure they begin to give more or less distorted pictures of their
real organization. The rounding up and increasing vacuolation which attend
the initial phases of cytolysis are evident in many published figures of species
in the group, including some in this paper.

Other reasons for the lack of observations on the Gymnodinioidae are the
rapidity of locomotion and incessant movements of many of the species, espe-
cially of the smaller forms. The larger ones, such as Noctiluca, readily permit
observation since flagellar activity is slight with reference to the total mass of
the organism, and both rotation and locomotion are relatively feeble in this
and other large forms. On the other hand, there are a host of minute forms
which have thus far eluded pursuit, or, if pursued by the aid of the mechanical
stage, they never stay quiet long enough at a time to permit observation, much
less an accurate drawing. We have not found it possible to make use of any
anaesthetic or fixing agent to bring these active forms under observation. The
few more resistant species, such as Polykrikos schwartzi and Gymnodinium
lira, which survive the diffusion currents resulting from the admixtures of sea
water and the chemicals used in fixation, are more or less contracted and dis-
torted, while the majority of species are wholly disrupted or mutilated and
contracted beyond recognition by attempts at fixation for cytological study.
The cytoplasm of these organisms is so nearly labile that the use of any of the
known cytological and protozoological methods has thus far failed to preserve
their structure satisfactorily for subsequent staining, mounting, and permanent
preservation of specimens. There are therefore few if any type specimens in
existence of species in this group.

The investigator of the group is thus limited to the primitive and simple
method of observation of the living organism in action. This has its advan-
tages, for while we may not determine the finer cytological detail as preserved
more or less imperfectly in the coagulated and sectioned substance of the
organism, we do have, under such conditions of examination of these active and
mobile dinoflagellates, a near approach to the normal form, and in most cases
an exceptional transparency of the living substance, which makes possible an
analysis, in the natural state, of internal structure, to a degree of completeness
which is rarely equaled in the investigation of the Protozoa.

4 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The discovery of the unusual amount of material of this group which has
been made by us in the waters off southern California is in part due to the
oceanographic conditions prevailing in our field of operations. These are seen
in the eupelagic area, that is, typical ocean water of the high seas, little modified
by tributary streams and free from dominating coastal influences such as are
created by a much indented coast line or an extensive archipelago.

The temperatures during the months of July and August at the surface
of the sea off La Jolla range from nineteen to twenty-one degrees Centigrade
(McEwen, 1916). These are characteristic of warm temperate seas. The
salinities are free from disturbances by discharge from rivers or by local rains
during this season. The upwelling of waters from below against the coast, and
apparently also against the steep slopes of the outer limits of the continental
shelf, enriches the surface levels off the California coast with nitrogenous com-
pounds brought up from the depths of the sea. Evidences of this enrichment
are to be seen in the wealth of the pelagic fisheries, in the submarine forests of
giant kelps, and in the recurrent outbreaks of red water due to the rapid de-
velopment and consequent enormous numbers of dinoflagellates, usually of
Gonyaulax polyhedra, which recur yearly off the shores of southern California,
especially from July to September.

An additional oceanographic factor favoring the occurrence of the warm
water fauna off southern California during the summer months is the influence
of the inshore, north-bound, return current which moves northward along
Lower California in an increasing volume and to a higher latitude as the season
advances to the culmination of its northward flow in December or thereabouts.
This tends to bring more tropical contributions to the offshore plankton, as
well as to bring about a rise in temperature.

This combination of stable, favorable oceanographic features constitutes an
ideal environment for these delicate organisms, attuned as they are to environ-
mental changes of small amplitude. Owing to the rapid increase in depth off-
shore and to the slight modifications of the shore line, the conditions of the
littoral zone adverse to pelagic life are confined to a relatively narrow belt
off the California coast, so that the pure water of the high seas with its fairly
stable conditions of temperature and salinity, and freedom from detritus and
continental wastes, is to be found within a few miles of the laboratory of the
Seripps Institution for Biological Research at La Jolla. Few institutions and
few localities in the world are so favorably located for the study of this group
as is the laboratory at La Jolla.

MATERIAL AND COLLECTIONS

The material upon which these studies are based was obtained for the most
part in the summer of 1917, from June 1 to August 25. The organisms were
obtained in the first place in towings made with a plankton net of No. 12 silk
towed at the surface along the new pier at the Biological Station, about one

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA

On

thousand feet offshore. Collections were taken at intervals of four hours
throughout the day and night. In addition to these collections another series
was made intermittently during the summer of 1917 at distances of two to five
miles offshore over depths of one hundred to six hundred fathoms.

The success we have attained in securing the striking representation of the
group here revealed has been due to the opportunity to get living material
promptly into the laboratory from oceanic conditions some distance offshore.
This was accomplished in the summer of 1917 by certain modifications of the
earlier methods, which had involved the use of short tow nets of No. 20 silk
bolting cloth with an opening of fourteen inches in diameter and a length of
about forty inches. The amount of plankton taken in these was large, and
presumably only the hardier species survived the crowded conditions and the
delay attendant upon bringing in the collection by the slow motor boats then in
use. In 1917 a smaller net, five inches in diameter and fifty inches in length, of
No. 25 silk bolting cloth (the equivalent of No. 20 of earlier years in having
approximately 40,000 meshes per square inch) was adopted. This was lowered
to a depth of eighty meters, three to six miles offshore, towed at that level
slowly for twenty minutes and then brought to the surface by hand. The
bottom of the net terminated in a four-ounce, wide-mouthed bottle, which was
tied in the end by a lashing and served as a detachable plankton bucket. The
eatch was transferred at once to a quart jar of fresh sea water and hurried
to the laboratory by speedy motor boat for examination, with the result that
these delicate animals were found in unprecedented frequency and exceptionally
fine condition.

The amount of plankton during the summer months of 1917 was at no time
large, and often the catch in the bottle was so small as to be scarcely visible
to the naked eye. For this cause, as well as by reason of the small orifice of
the net, the catch was small, and owing to the relatively large filtration surface,
computed to be four times the area of the orifice, the rate of movement of the
water through the minute orifices of the silk was not rapid enough to destroy
the delicate Gymnodinioidae of the plankton. Furthermore, owing to the
absence of crowded conditions in our small catches and to the fact that the
‘‘Hllen Browning,’’ the fast boat of the Biological Station, has a speed of
thirty miles an hour, it was possible to convey the catch to the laboratory in a
quite normal condition.

A list of the earlier collections, most of which have been examined in fresh
and preserved condition, will be found in Ritter e¢ al. (1915, p. 156) in the list
of Preliminary plankton collections. Preserved collections of plankton are of
no value in the study of this group except for records of the occurrence of a
few of the more highly resistant and specialized forms, such as Polykrikos and
Gymnodinium lira, and even these are rarely found in such collections. Most
species do not survive the ordinary application of reagents used in preservation,
such as formalin.

6 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

MerHops

The necessity of working to a very large extent with living material, and
the very limited numbers of individuals to be found of any one species of the
group, except Polykrikos schwartzi and Noctiluca miliaris, have determined
the methods employed, and have excluded cytological investigations and any
consideration of life histories.

Promptly upon arrival in the laboratory the plankton was examined in
Syracuse dishes under the low power, and when some representative of the
group was detected it was isolated with a fine pipette, placed on a slide under
a cover glass and located with the aid of a mechanical stage. When its activ-
ities were slowed down it was usually possible to determine its dimensions by
the aid of the camera lucida, or even to get an outline of its more evident
structures. Interpretative sketches, color notes, and other details were gen-
erally obtained before the rounding up, cytolysis, and death of the organism
occurred. It was not always possible to get all the details from one animal,
or in some cases to determine all the desirable points in the brief time of
observation. This fact explains some of the deficiencies in our accounts of
these interesting animals.

Colors are recorded in the system of nomenclature of colors proposed by
Ridgway (1912). Certain very puzzling difficulties arise in any attempt to use
these plates of Ridgway’s with organisms illuminated by transmitted hght
under the microscope. Changes in the diaphragm, in the focus of the condenser,
in the objective used, or even in the source of light, all affect the color values
of the object. The same object may have very different color tones under these
changing conditions of illumination. Furthermore, it is impossible to find in
the Ridgway color samples the exact equivalents of all the colors of the dino-
flagellates when thus viewed. The brilliance and delicacy of the coloring of
these transparent objects is not reproduced in the opaque tones of the color
samples.

The varying refractive indices of the contained fat bodies and other refrac-
tive substances, and the color modifications induced by the rapid accumulation
of a pinkish fluid in a peripheral zone of vacuoles as cytolysis impends, all
combine to increase the difficulty of giving a correct interpretation of the color
values of these particolored organisms. In view of the reduction in color values
due to the amount of light necessary for observation with the higher powers
of the microscope and to the color changes due to approaching death, it is
probable that the colors as portrayed in our plates are not exaggerated, and
are, in some cases at least, much less brilliant than they are in nature.

Much aid in the trying process of pursuing these incessantly moving
organisms has been secured by the use of the high-power, binocular microscopes
of Leitz and of Bausch and Lomb. These have also proved invaluable in the
analysis of the complicated furrows and girdles of this group and in revealing
the true contour of the surfaces.

CHAPTER I

GENERAL MORPHOLOGY: SIZE AND FORM, MOTOR ORGANELLES,
FURROWS AND TORSION OF THE BODY

The Gymnodinioidae are among the least known of all the dinoflagellates
for several reasons. They are in the main found in oceanic waters or at least
where neritic influences are not potent. This pelagic habitat affords the second
reason for the obscurity surrounding the group, to wit, the very great delicacy
of the organisms and their extreme sensitiveness to adverse conditions. At
the best it is highly improbable that all the forms belonging to the group sur-
vive the turmoil of the plankton net, the changes in salinity, temperature,
pressure, illumination, ionization and proportions of dissolved gases incident
upon the transfer from the open sea to the film of water beneath the cover
glass, and to the concentrated light of the high-power microscope. For many
of them dissolution ensues within a few moments after they are placed under
the microscope for observation, with explosive abruptness and utter disruption
of all structural features, while even hardier forms contract more or less,
underge profound color changes and lose their characteristic features very soon
after exposure to the axial rays of the microscope.

One of the results of the great susceptibility of these organisms to slight
environmental changes has been the frequent appearance in the literature
dealing with these forms of figures of abnormal character, caused by changes
incident to microscopical examination. Another point which must be consid-
ered not only in studving the organisms themselves, but in any review of the
literature dealing with them, is the great transparency of their bodies and the
trap which may thus be set for even experienced biologists. The importance
of this fact hes in the liability of the operator to mistake the opposite side of
the organism under the microscope for the side nearest him or uppermost, with
the result that the orientation of the organism is completely reversed. There
are many instances of such reversed orientation recorded in the literature
(Kofoid and Swezy, 1917) even among veteran investigators, as that of Nema-
todinium armatum (= Pouchetia armata) by Dogiel (1906), where the girdle is
drawn as though extending from the ventral face to the right of the body and
over dorsally to the left, a complete reversal of its actual course.

These conditions call for caution in dealing with the group, even where an
abundance of material and a variety of forms have been present, as in our own
work on these organisms. Some of the pitfalls have been avoided, but others
unwittingly may have been overlooked.

8 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

For the convenience of the reader the following brief outline of the Dino-
flagellata is here given. The group contains two orders, the Adiniferidea with-
out a girdle and the Diniferidea with a girdle. The former contains two tribes,
the Athecatoidae, without cuirass, as Haplodinium, and the Thecatoidae, with
enveloping cuirass, as Prorocentrum. The Diniferidea are likewise divided
into two groups, the Gymnodinioidae or naked forms and the Peridinioidae or
armored forms, such as Peridinium. Both of these groups contain a few species
of doubtful relationships. The Gymnodinioidae contains seven families, to wit,
Protodiniferidae, Gymnodiniidae, Polykrikidae, Noctilucidae, Pouchetiidae,
Blastodiniidae, and Cystodiniidae.

In the following discussion of the tribe Gymnodinioidae the chief emphasis
is laid upon those members of the group comprised in the families Protodini-
feridae, Gymnodiniidae, Pouchetiidae and the genus Pavillardia in the Nocti-
lucidae. Attention is not confined, however, to these forms alone, but illustrative
material is drawn upon from the entire Dinoflagellata where pertinent to the
subject in hand.

Size AND Form.—As a group the Flagellata probably has a smaller average
size for its members than most of the other large groups of Protozoa. The
two subdivisions of this group which attain the maximum size found within it
are the Trichonymphidae and the Dinoflagellata, and of these two the latter
presents some of the greatest variations in size found within the group, having,
at one end of the scale, the largest individuals and, at the other end, some of
the smaller, though not the smallest ones, thus far described for the Flagellata.

Within the Gymnodinioidae (excepting Noctiluca) these variations in size
extend from 11 to 212 for the motile flagellated individuals, but some of the
parasitic forms attain a length of 700, The maximum size within the group
is, however, attained by Noctiluca, which may have a transdiameter of 1 to
1.5mm. The average length for members of the Gymnodiniidae is about 100z.
The greatest size in this family is found in the more specialized members of
Gymnodinium, such as G. pachydermatum and G. dogieli (figs. AA, 5, 8), and
in Cochlodinium, such as C. strangulatum (fig. GG, 8). Next to these in size
comes the Pouchetiidae, whose largest members are somewhat smaller than the
largest members of the other group, but whose smallest members do not reach
the lower extreme in size (figs. KIK—RR), all the species being nearer the
average than are the species in the other genera, Gymnodinium, Gyrodinium,
and Cochlodinium.

The variations in size within the species cannot be stated with any degree
of certainty, owing to the lack of knowledge of the amount of growth that may
take place within a single developmental cycle, and often also to the small
number of individuals of a single species that can be found, even with pro-
longed searching. In forms which are obviously members of a single species,
variations of a third, or slightly more, may sometimes be noted in the length.

Other factors which make a determination of the variation in size within
the species very difficult are the extreme sensitiveness and ready response of

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 9

these delicate organisms to slight environmental changes. These responses are
usually shown in the form and dimensions of the body. It is only in compara-
tively rare cases that an individual may be kept under observation under the
microscope long enough for a complete camera drawing, without these changes
in the body manifesting themselves. Often indeed they have begun when the
drop of water containing them is first imprisoned by the cover slip (fig. A).

Fig. A. Variations in size and shape of Gymnodinium rubrum sp. nov. 1. Individual showing the normal
appearance of the body. 2-5. Individuals all taken from the same haul and showing variations in size and shape.
X 355.

These changes consist of a gradual but slight increase in diameter and a pro-
gressive rounding up of the body, with obliteration of the furrows, ending in
complete disruption of the entire organism. The rounding up or thickening
of the body, resulting in a diminished length and increased diameter, is a
common condition in plankton hauls that have remained in the laboratory for
half an hour or more, particularly if any great length of time has elapsed
between the actual taking of the haul and its appearance in the laboratory.
In hauls containing an abundance of material this degenerative process is much
more rapid than where the change from the more highly oxygenated oceanic
waters is not emphasized by overcrowding.

The same effect may sometimes be produced by the ingestion of large food
bodies, that is, the body becomes shorter and broader to accommodate the food
mass (pl. 5, fig. 56). After the process of digestion is completed the body
gradually resumes its normal shape and size.

10 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The shape of the body of the lower members of the dinoflagellates approaches
that of the typical flagellate, that is, a slender pear-shape with the flagella
attached at the anterior end. This is shown in Haplodinium (fig. R, 5).
Starting out from this simple type the first changes are found in the gradual
shifting of the location of the flagella, which may have their origin at any point
between the anterior and posterior ends of the body (fig. R). With this back-
ward shift of these organelles the form of the body responds to the change by
assuming a spindle-shape, which is the predominant one among the dinofla-
gellates, though often secondarily modified, as in the dorsoventral compression
of the body in many species of Amphidiniwm.

Further modifications of this primary shape are found in the extension of
the labile posteroventral sulcal area of Cochlodinium and Pouchetia, culmi-
nating in the prod of Erythropsis (fig. T). This latter genus is further modi-
fied by the thickening of the body, giving it a squat appearance typical of all
the members of the genus (pl. 12). A few species of Gymnodinium (figs. X,
7, 8, 26) seem to have acquired a permanently rounded form.

One of the most striking and characteristic features of the body is its
bilateral asymmetry, following the rule obtaining throughout the Protozoa
generally, where complete bilateral symmetry is the exception outside of some
of the Radiolaria. This bilateral asvmmetry is directly correlated with the
spiral course in locomotion, and may be one of the factors in the maintenance
of the organism near the surface of the sea. Kofoid’s studies (1910b) on the
thecate dinoflagellates point to the conclusion that optimum conditions of ex-
istence for the members of this group he within the upper levels of more or less
illuminated water, and that descent below this region is fatal for them. The
apparent lack of special organs for flotation, other than vacuoles, is compen-
sated for by the asymmetry of the body, and in the thecate forms, where a
greater appreciable overweight of the body is present, by the formation of horns
and fins. These combined with the rotation of the body caused by its asym-
metry impede the descent of the organism into lower regions in response to
gravity. Having a lighter specific gravity and greater powers of locomotion,
the need for additional structures to meet this response is less insistent in the
naked dinoflagellates than in the thecate forms.

An increasing torsion or twisting of the body, beginning with the genus
Gyrodinium (figs. CC-EE), reaches its culmination in the genus Cochlodinium
(figs. FF-HH), where the twisting of the body, as shown by the course of the
girdle, may be as great as four complete turns, as in C. augustum (fig. HH, 15).
This is correlated with the movements of the flagella, combined with the pressure
exerted by the water on the more plastic species of the genus. In the thecate
forms this backward reach of the distal end of the girdle has not developed
bevond the Gymnodinium and Gyrodinium types, showing either a loss of plas-
ticity in the body structures accompanying the relatively slight locomotor powers
of the skeletal-bearing forms, or else indicating the origin of these forms from
ancestors similar in lack of torsion to these two genera in the Gymnodiniidae.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 1]

Moror ORGANELLES.—The most important structures of the protozoan organ-
ism, from a systematic point of view, are its motor organelles. In the Flagellata
these consist of flagella and vary in number and position in the different groups.
The dinoflagellates are characterized by the presence of but two flagella of
different types, transverse and longitudinal, each having its own definitely
located position, and, in the case of the transverse flagellum, a structure peculiar
to this group. The longitudinal flagellum is threadlike in form, trailing after
the body, and held more or less rigidly in position, or waving in broad curves
(fig. B. long. fl.) or with intense terminal activity. It arises from the posterior
pore (fig. B, post. p.) in the sulcus, in case there are two pores, and its proximal
part les in the ventral sulcus (szle.) near the major axis. The transverse
flagellum (fig. B, tr. fl.), on the other hand, runs around the body in a nearly
transverse plane, arising from the anterior pore near the proximal end of the
girdle (fig. B, ant. p.) and is often, if not always, ribbon-like in form; it moves
in a close-set spiral, or undulating wave of contraction, and is usually lodged
in a deep, encircling groove, wound in a flat or more or less steep spiral from
the left ventral face around dorsally to the right side in a more or less complete
girdle of one or even several turns (fig. C). In the Adiniferidae and in a few
other isolated cases both flagella arise from the same pore placed at or near the
anterior extremity of the body (fig. R, 7). In the majority of forms the two
flagella arise from two different pores on the ventral surface, and not infre-
quently at considerable distances from each other (fig. C, 10).

The transverse flagellum itself consists of a deeply staining thread or stout
fibril, bordered on one side by a comparatively wide, finlike sheet of trans-
parent protoplasm or membrane, somewhat greater in length than itself, and
thrown into ripples or folds of wider amplitude than the fibril. This is in
constant, wavelike motion progressing from the proximal end distally. Re-
versals in direction have occasionally been noted. The flagellum arises from
a large deeply staining blepharoplast situated somewhat below the surface of
the body. Accurate cytological investigation of its internal relationships has
not thus far been made with any degree of success.

This fundamental organization of the motor organelles may be obscured
in several ways. In the Adiniferidae the girdle and sulcus are not developed
(figs. R, 5-7), although the nucleus is of the dinoflagellate type, as are also the
two flagella the form and function of which are strikingly suggestive of those
of the dinoflagellates included in the Diniferidae. They also possess a porulate
theea in the tribe Thecatoidae. In Protodinifer (fig. R, 2) the very faintly
developed girdle clearly forecasts the fundamental relationships of this organ
found in the remainder of the dinoflagellates. It probably represents the be-
ginnings of the development of these peculiar relations within the group.

In the Diniferidae this fundamental organization is sometimes obscured by
the interposition of long encysted stages, with a consequent shortening of the
dinoflagellate stage of the life cycle, by secondary loss of the flagella with the

12 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

addition of new organelles, and by parasitism, with its resulting profound
modifications of the entire organism.

In those organisms included in the old group Pyrocystidae (or Pyrocys-
taceae), which probably represent typical eneysted phases in the life cycle of
certain genera of the dinoflagellates, the encysted stage or period has become
prolonged, while the free, motile gymnodinium-like stage is reduced to a rela-
tively short period (fig. I). It is in the free, motile stage, usually obscured in
the huge, inflated sphere of the encysted organism, that its relationships to other
dinoflagellates and the usual details of its specific organization must be looked
for. The details of the loss of flagella and their subsequent outgrowth in these
stages have not been followed. In the ordinary encysted stage of the Gymno-
diniidae both flagella are apparently absorbed at the beginning of encystment,
and towards the end of the period may be seen as very short outgrowths, indi-
cating a new formation for both flagella. The possibility of their being cast
off is not precluded. It is not uncommon to find encysted individuals with
neither longitudinal nor transverse flagella present.

A still more profound modification has taken place in the little known group
of parasitic dinoflagellates. The free, motile stage, which is brief, and alone
shows the genetic relationships of the species, has the characteristic organiza-
tion of Gymnodinium, with the typical motor organelles (fig. J, 5). With the
beginning of a parasitic career these are lost and the organism becomes a huge
non-motile, sacklike structure infesting the tissue of its host (fig. J, 1).

In Protodinifer (fig. R, 2), Pavillardia (fig. JJ), Noctiluca, and most strik-
ingly in Erythropsis (pl. 12), the development of a tentacle or prod has resulted
in the loss or almost complete disappearance of the longitudinal flagellum. An
occasional individual, with both flagella in addition to the prod in Erythropsis,
asin #. minor (pl. 12, fig. 181), confirms the suspicion that this condition is only
a secondary modification. In Noctilwca the transverse flagellum also has been
reduced in size and lies in a short groove which soon fades out and is probably
the remnant of a girdle (fig. KK), though the inflation of the body makes its
exact status difficult to determine.

The normal function of the prod of EKrythropsis in the usual habitat of the
animal is not made evident by the activities observed. KHrythropsis is a eupe-
lagic organism. It is a member of a group of dinoflagellates, none of which, ex-
cluding Amphidinium, so far as evidence at hand goes, ever has normally any
relation whatever to the substrate. Moreover, as far as our limited observations
go, it could not compare with the usual flagellar equipment of the Gymnodi-
nioidae as an organ of propulsion in free-swimming movements. It might give
a spasmodic thrust to the body, but its presence, in EH. extrudens (pl. 12, fig.
130) especially, constitutes a serious impediment to locomotion, at least in the
extended state, since it considerably increases the resistance of the body to the
water, and, unless thrown back into a trailing position, its asymmetry, with
respect to the main axis of rotation and progression, is formidable.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 13

Two other functional possibilities of this prod remain. The prod may be
either a feeding or a defensive structure. The energetic retractions combined
with the capitate end of the tentacle would tend to press any object against
the ventral furrow if caught between it and the body on its anterior face.
Erythropsis extrudens has no chromatophores. No food bodies were noted in
the individuals observed. Many if not all Pouchetia, Cochlodinium, and
Gyrodintum are holozoic. Holozoic nutrition is indicated for this species also
and the tentacle might be effective as an organ of ingestion.

Observational evidence is likewise lacking for the second function suggested
above, namely, that of an organ of defense. In fact in all our observations on
living holozoic Gymnodinioidae no instance of active capture and ingestion of
food has been seen. It is obvious, however, from the size and activities of this
tentacle that a marauding holozoic dinoflagellate, such as a Pouchetia, Cochlo-
dinium, or the larger Polykrikos, or even Noctiluca, would find it rather difficult
to capture, hold, and engulf a vigorously kicking Krythropsis. The function
of the tentacle as an organ of defense is not incompatible with that of the
capture of food, although the operation in either fashion involves contradictory
internal states on the part of the organism, conditioned by hunger and satiety
or by the nature of its contact with other organisms.

Another type of structure, the value of which as a motor organelle in these
forms is problematical, is the peculiar form of pseudopod formation which has
been described by Zacharias (1899) for a chromatophore-bearing Gymnodinium,
G. zachariasi (fig. BB, 3). This has been cited by West (1916) as indicative
of holozoic nutrition, but Zacharias offers no evidence that these structures are
used in the capture of food or as motor organelles. They are outgrowths of
the extremely plastic sulcal area, modifications of which are found in Cochlo-
dinium, and Pouchetia, culminating in the prod of Erythropsis (fig. SS). The
loss of the longitudinal flagellum in those forms in which the prod or tentacle
is well developed might indicate that its function is, to some extent at least, sub-
served by the new organelles thus introduced. Evidence on this point, however,
is lacking. Such retractile processes are not unlike those recorded by Rhodes
(1920) for the holozoic polymastigote flagellate, Collodictyon. Similar
pseudopodia-like processes are functional in this genus in capturing organisms
for food.

Furrows AND TorSION OF THE Bopy.—Closely connected with the motor
organelles, both morphologically and in their evolutionary development, and
equally important from a systematic point of view, are the furrows of the body
of the dinoflagellate. They constitute its most striking structural features.
All stages of development and elaboration of these peculiar and characteristic
structures are found within existing species of the group, from the fine, faint
traces in the lower forms to the spiral of three or four turns in the more special-
ized Cochlodinium, and to the elaborate furrows outlined by lists or fins of great
beauty and delicacy of design in the thecate forms of Gonyaulax, Peridinium,

14 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

and Ornithocercus. It is in the non-thecate forms that the development and
fundamental relations of the furrows may be most clearly seen.

These furrows are two distinct structures, the more conspicuous of which
is the furrow or girdle passing around the body in a transverse direction (fig.
B, gir.). Its course is that of a descending left-wound spiral, with the ends
usually more or less widely displaced. The second furrow is a longitudinal
one, the sulcus, connecting the ends of the girdle, sometimes continuing on to
the apices (fig. B, swlc.). Its course is morphologically longitudinal and in
most of the genera its increasing
length keeps pace with the increasing
torsion of the body. This gives it a
spiral path around the body in the
more highly specialized members of
the group, as in Cochlodinium (figs.
GGs ERED).

These two structures, the girdle
and sulcus, are usually present at
some period of the life cycle of nearly
every member of the Dinoflagellata
outside of the Adiniferidea. In the
latter the furrows are entirely lack-
ing. In the genus Protodinifer, the
most primitive of the Diniferidea
(fig. R, 2), the girdle is merely incip-
ient, short and poorly developed, its
length being less than 0.3 transdiam-
gave: 2: ee URN SRE resp a Fal eter of the body. The sulcus con-
aha aetna ae Bees nected with it is also short and feebly
longitudinal flagellum; n., nucleus; pig., pigment; post. p., developed, and is occupied posteriorly
SR Uae ee eee sule., sulcus; tr. fl., trans- by a stout, rodlike tentacle, which

, - projects a short distance beyond the
body. The junction of the proximal end of the girdle and sulcus here, as in the
typical dinoflagellates, is occupied by the anterior pore from which issues the
transverse flagellum. The transverse flagellum in Protodinifer occupies the
girdle and continues its course around the body beyond the incipient girdle, its
length frequently being greater than one complete turn. In the members of
the Adiniferidea, such as Prorocentrum and Haplodinium, the anterior ex-
tremity of the body is marked by a shallow notch from which arise the two
flagella (figs. R, 5, 7), without any indication of a girdle.

In the Diniferidea the girdle and sulcus are thus the outstanding features.
In Oxyrrhis, a second primitive genus, the girdle is posteriorly located, its
proximal border well developed, but not its distal one, resulting in a wide de-
pression of the posterior portion of the body (fig. R, 3). The typical form of
the girdle is first attained in the Gymnodiniidae, where it is usually complete

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 15

and well defined, with clearly marked, equal borders. Its length varies from
0.5 of a turn around the body in Hemidinium (fig. C, 1) to four complete turns
in the more highly specialized species of Cochlodinium (fig. C, 10). It may
form a complete circle about the body, as in a few of the simpler Gymnodinium
(figs. X, 1, 2, 8), or its ends may become displaced, so that the distal end comes
to lie nearer the posterior region of the body than to the proximal end, as in
Gyrodinium (fig. CC). Its course thus becomes a more or less steep, spiral
path around the body.

Fig. C. Types of girdle arrangement. 1. Hemidinium nasutum Stein. After Stein (1883, pl. 2, fig. 24).
2. Amphidinium steini (Stein). After Stein (1883, pl. 17, fig. 9), slightly modified. 3. Amphidinium scissum
sp. nov. 4. Gymnodinium doma sp. nov. 5. Gymnodinium rubrum sp. nov. 6. Gyrodinium spumantia sp. nov.
7. Gyrodinium contortum (Schiitt). After Schiitt (1895, pl. 21, fig. 65). 8. Cochlodinium pirum (Schitt). After
Schiitt (1895, pl. 23, fig. 76). 9. Cochlodiniwm clarissimum sp. nov. 10. Cochlodinium augustum sp. nov. X 500.

With this posterior displacement of the distal end of the girdle an increase
in length takes place which, in some of the species in Gyrodinium, becomes
greater than one turn of the body (figs. CC, 22; DD, 17). This produces a
torsion of the body which continues with the increasing length of the girdle
until it may make two (fig. C, 9), three (fig. HH, 16), or even four complete
turns of the body, which is the maximum length reached in Cochlodiniwm
(fig. C, 10). Closely correlated with the length of the girdle and the resulting

16 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

torsion of the body is the torsion of the suleus which of necessity is carried
around the body in a spiral course, usually one turn less in length than that of
the girdle (figs. GG, HH).

The increased length of girdle and sulcus, with the consequent torsion of
the body. results in a profound modification of its dorsoventral plane. In
Gymnodinium, which lacks appreciable torsion, the plane passing through the
two flagellar pores marks the dorsoventral plane of the body and is longitu-
dinal. These two pores are usually located at the junctions of the girdle and
suleus, the anterior pore at the anterior junction, the posterior pore at the
posterior junction. The latter pore may frequently open into the sulcus
posterior to the junction, but only rarely anterior to it.

In the simpler Gymnodinioidae these two pores are placed near together,
as in Oxyrrhis (fig. R, 3), Hemidinium (fig. R, 4), many Amphidinium (figs.
U, 2, 3, 10, 25), and Gymnodinium (figs. X, 2, 14). They still lie, however,
in a longitudinal plane passing through both apices. In some species of the
last two genera the pores have become widely separated (figs. U, 1,4; X, 5; AA,
6), a condition which is common for the more specialized genera, as Gyrodinium
(figs. CC) and Cochlodinium (fig. GG), as well as in the Pouchetiidae, where
the ends of the girdle are more or less widely displaced. In these species, where
appreciable torsion of the body is found, the morphologically dorsoventral plane,
passing through the two pores, becomes correspondingly twisted, and ceases to
lie in the geometrical longitudinal plane passing through both apices.

With the gradual increase in the length of the girdle in Gyrodinium and
Cochlodinium the posterior end of the girdle is pushed farther around the
body, carrying with it the posterior pore and sulcus, as well as the morphological
ventral surface lying between the two pores. With the continued increase of
the girdle up to two complete turns of the body, the morphological dorsoventral
plane undergoes a corresponding torsion with these structures, although the
general biconical or fusiform shape of the body as a whole differs little if at
all from that of the non-twisted forms. As a result of the torsion, the ventral
surface established by the presence of the sulcus follows the torsion of this
structure in its one to four turns (as in Cochlodinium augustum) around the
longitudinal axis of the body. Thus the position of the anterior pore alone does
not determine the ventral face of the organism.

The sulcus represents the most mobile, plastic portion of the organism. It
is the region for the ingestion of food and hence is capable of great distension,
judging by the size of the organisms sometimes ingested. In Cochlodinium
roseaceum (pl. 8, fig. 85) the ingested Pouchetia has a length of 0.48 of the
length and a breadth of 0.33 of the transdiameter of the Cochlodiniwm which
has mastered it. In C. vinctum (pl. 2, fig. 15) the food mass contained within
its body has a length of 0.7 and a width of 0.41 of its own dimensions respec-
tively. A still more striking instance is found in Pouchetia voracis (fig. PP, 2),
where a thecate Peridinium has been successfully captured. The cytoplasm

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA i

had evidently been digested before it came under our observation, the remaining
theca presenting the appearance of being crushed together and of massing near
the posterior end of the body, preparatory to being ejected on the release of
the organism from its cyst. Peridinium of this type are large organisms and
the half shell still intact has a length equal to about 0.5 of the total length of
the body of the Pouchetia, showing that the ingested organism was about equal
in size to the marauder which had captured it. The length of the intercin-
gular area in this species is about 0.5 of the total length of the body, hence its
distension must have been enormous to enable it to grapple successfully with
a food mass of this size.

In its simplest condition the sulcus is a shallow furrow joining the ends of
the girdle, but this stage is relatively rare, as it usually presents various modi-
fications. The anterior and intercingular portions of the sulcus usually present
few variations of structural details beyond the apical loop. Its posterior ex-
tension may sink into the body, forming a deep excavation at the antapex, or
it may even bifurcate the entire posterior half of the body, as in Gymnodinium
bifurcatum (fig. AA, 3). In Amphidinium the sides are often drawn out into
flaps which are thrown across the furrow and cover the opposite border (fig.
21,5). It may also function in the production of pseudopodia (Zacharias,
1899), asin Gymnodinium zachariasi (fig. BB, 3), in the tentacle of Protodinifer
(pl. 7, fig. 74), in the ventroposterior process of Proterythropsis (pl. 11, fig.
123), and in the prod of Hrythropsis (pl. 12).

Its extreme mobility is undoubtedly correlated with its function as the
mouth of the organism. The process of food-taking in the dinoflagellates is
stilla mystery. Many of the forms observed in the cytoplasm are those of active
organisms and the means by which they are caught and held until the engulfing
protoplasm receives them are puzzling in the extreme. The great mobility of
the lips of the sulcus probably offers a solution to the puzzle. Saville-Kent
(1880-82) observed Gymnodinium marinum actively devouring smaller monads
in the culture with it, engulfing them at this region without the formation of
pseudopodia. Critical evidence as to the exact nature of this activity in other
members of the group is almost entirely lacking.

CHAPTER II

FJENERAL MORPHOLOGY: NUCLEI, PUSULES, OCELLI,
NEMATOCYSTS

Nuciet.—The Dinoflagellata are definitely marked off from the remainder
of the Flagellata by certain features which are distinct and peculiar to the
group. Two of these features, the furrows and the two types of flagella, have
already been discussed. Another organelle no less peculiar is the nucleus with
its moniliform chromatin threads, one of the most characteristic structures
found within the group, and, in some respects, the most constant feature of its
organization. It retains its typical appearance during encysted stages when
the flagella are lost and the furrows have become obliterated (fig. P) and forms
the only distinguishing mark of the organism.

Its appearance in the living organism is usually remarkably clear and dis-
tinct. Schutt, in his monograph on the dinoflagellates (1895), clearly illustrates
its structure in very many members of the group. It is usually relatively large,
varying from spheroidal to ellipsoidal in shape, sometimes greatly elongate as
in Torodinium (fig. I1), and slightly curved to conform with the contour of
the body (pl. 10, fig. 115). The latter type is more frequently found in the
thecate forms, but in both cases is probably only a predivision stage. The
relative size may vary considerably in individuals of the same species.

The nucleus is surrounded by a distinct membrane which is often double-
contoured. In a few species it is surrounded by a wide zone of clear, homo-
genous appearance (pl. 6, fig. 63), which in others, as in Gyrodinium corallinum
(pl. 10, fig. 117), may be filled with large, fairly regular alveoli. In the living
organism its chromatic contents present an organization of moniliform threads,
the constituent granules of which are rather coarse and closely pressed together
in linear rows (fig. X). The chromatin threads may be variously arranged,
coiled, or in parallel rows, and fill the entire nucleus. The threads vary in
length with the size of the nucleus and usually follow its longer axis in more or
less of a spiral with the ends of the threads sometimes apparent at the poles of
the nucleus. Nucleoli may be present, lying imbedded in the mass of chromatin
threads (fig. U, 10).

The structure of the nucleus varies but little in the different groups. In
Erythropsis the chromatin network is rarely visible in the living form, the
nucleus presenting that glaucous appearance noticeable in the entire organism
(ple t2)).

The position of the nucleus is generally near the center of the body, though
this may vary greatly throughout the different groups. Its position may also
be changed by the presence of ingested food bodies within the cytoplasm.

Nuclear division in the dinoflagellates has received comparatively little
attention, yet they possess a distinct type of mitosis closely correlated with the

[18]

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 19

massive size and great number of the chromosomes. They furthermore show
indications of a high degree of specialization along several lines. One of these
is the development of a paradesmose, which reaches its maximum in Noctiluca
with its ‘‘sphere,’’ consisting of a mass of archoplasm containing the centro-
some, which forms the axis of the karyokinetic figure. The role of the para-
desmose (centrodesmose) in the dividing nucleus of these forms is one which
still requires explanation and confirmation. The conflicting figures of Jollos
(1910) and Borgert (1910) on this point in Ceratium show clearly the need
of further investigation.

Another line of development is indicated in the large, distinctly marked
chromosomes which, in some cases at least, do not entirely lose their individ-
uality from one mitosis to another. In the living organism these are remark-
ably clear, appearing as moniliform threads of a clear, homogenous substance,
and are evident in most of the individuals observed.

Figures of binary fission in the dinoflagellates are frequent in the literature,
but a critical analysis of the various steps in the process has been made in only
a few cases. Outside of the classical example of Noctiluca, only one member
of the Gymnodinioidae, Gyrodinium fucorum (Gymnodinium fucorum) Jollos
(1910), has thus far received such attention. The mitotic process has been out-
lined most fully in the theeate forms by Lauterborn (1895) in Ceratium hirun-
dinella and in Ceratium tripos by Borgert (1910). The work of Jollos on
Gyrodinium fucorum, though incomplete, combined with the scattered refer-
ences to this subject that may be found in the literature, and our own obser-
vations on these forms, clearly indicates that the process is essentially the same
for the majority, at least, of the Gymnodiniidae as that which has been described
for the thecate forms. This conclusion is further strengthened by the identity
in nuclear structure between the thecate and non-thecate dinoflagellates. As
illustrative of the process of mitosis in this group we have therefore selected
Borgert’s work (1910) on Ceratium tripos var. subsala.

At the onset of division the ordinary spheroidal or ellipsoidal nucleus be-
comes elongated and, in some cases at least, the surrounding membrane is lost
(fig. D, 1). The chromosomes lose their earlier parallel or subparallel arrange-
ment and are found in a tangled skein or spireme, grouped in pairs (fig. D, 2).
According to Borgert, this is the result of a longitudinal splitting of the indi-
vidual threads. Lauterborn (1895) did not figure this stage in Ceratium
hirundinella, nor did Jollos (1910) for Gyrodinium fucorum, Ceratium tripos
or C. fusus. The work of both of these investigators left this stage still unde-
termined.

Following the spireme phase the chromosomes become arranged in an
equatorial plate (fig. D, 3). In all cases the polar axis of the mitotic figure or
spindle at this stage, as shown by the position of the chromosomes, lies in the
short axis of the nucleus, necessitated doubtless by the great number of chro-
mosomes. A definite spindle has not been figured by Borgert, Lauterborn, or

20 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Jollos, though faint indications of it may be found in the cytoplasm beyond the
ends of the chromosomes in some of Borgert’s figures (fig. D, 4).

The next step in the process is the separation of the chromosomes into two
groups (fig. D, 4) and the formation of the new daughter nuclei (figs. D, 5, 6).
The chromosomes do not in this process lose their subparallel positions, but

Fig. D. Division of nucleus of Ceratiwm tripos var. subsala forma typica. After Borgert (1910, pl. 1, fig. 2;
pl. 2, figs. 11-15). 1. Resting stage of nucleus. 2. Prophase with nucleus showing a segmented spireme with
each thread double. 3. Equatorial plate stage. 4. Metaphase with division of the chromosomes. 5. Beginning
of the anaphase. 6. Later anaphase. X 800.

this state seems to continue into the succeeding phases of nuclear development.
In the dividing nuclei of Cochlodinium elongatum (pl. 4, fig. 45) the same
appearance may be observed in the two newly formed daughter nuclei.

Jollos has figured for Gyrodinium fucorum, Ceratium tripos, and C. fusus
a ‘‘centrodesmose’’ connecting two granules which seems to have a very prob-
lematical relation to the mitotic figure. This, as well as other obscure points,
such as the exact method of division of the chromosomes and the presence of a
spindle, still requires further investigation before they can be definitely settled.

The whole process of mitosis is of a relatively simple type which, correlated
with the massive size and great number of chromosomes, makes it a distinctive
one in the Flagellata. The evidence for the continuity of chromosomes from
one division cycle to the next lies in the fact that the appearance of the daughter
nuclei in the late telophase stage (fig. D, 6; pl. 4, fig. 45) is similar to that pre-
sented by the nuclei after final division of the body (fig. L, 2), and throughout

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 21

the ordinary trophozoite stage (pl. 8, fig. 83; pl. 10, fig. 114), without evidence
of an intervening stage in which the moniliform chromatin threads or chromo-
somes are broken up.

Attention must be called to the appearance of the nucleus, as figured by
Borgert, also by Lauterborn and Jollos, before the onset of division. The
chromatin here lies imbedded as minute granules in the meshes of a reticulum
that fills the entire nucleus, usually with one or more large nucleoli also present.
This is in marked contrast to the appearance of the nucleus of the living organ-
ism. In the hundreds of individuals observed by us the nuclei presented a
fairly uniform and characteristic appearance. In no instance has a network
been visible and in only a very few cases have the granules been arranged in
other than definite linear series. One of these is Gyrodinium corallinum, where
a modification of the usual type of nucleus is present in the form of a sur-
rounding alveolate zone (pl. 10, fig. 117). In a few cases the nuclei seemed
homogenous, but usually they presented the distinct moniliform threads as
shown in our figures. In a few instances these have been omitted in both the
line drawings and the colored plates to avoid a too great mass of detail. With
proper lighting conditions this structure can usually be demonstrated in the
living organism.

The change of these linear threads to the minute granules enmeshed in a
reticulum in the stained specimens may be due solely to the action of the fixative
used in preserving the material. That a very great change takes place in proto-
plasm as well as nucleoplasm in the action of any chemical upon them is evident
to any one working upon the living, in connection with stained, material of any
protoplasmic body.

Chatton (1914) has made per-
haps one of the most important
contributions to this question of
nuclear structure in the dinoflagel-
lates in his work on the parasitic
forms. In Blastodinium crassum
he figures (fig. E) details of nuclear
structure, which clearly point to a
greater complexity in the process
of mitosis than has yet been dem-
onstrated for the free-living dino-
flagellates by any other investigator.

The appearance of the tropho-
eyte, as Chatton has termed this

peculiar, binucleated stage of the Fig. E. Blastodinium crassum Chatton. After Chat-
ar See ton (1914a, figs. 1-4). Abbreviations: c., centrospheres ;
life Cy cle of Blastodinium crassum n., nuclei; plas., plasmodendrites. 1. Trophocyte in nor-
(fig. Ki, I) represents a dinoflagel- mal vegetative phase. 2. Sporocyte with remnants of the

centrospheres still visible. 3. Sporocyte farther advanced

late in the late metaphase in which with centrospheres completely obliterated. 4. Sporoeyte
further development has come to of nearly last division stage. X ?

22 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

a standstill. At the opposite poles of the nuclei are large, conspicuous
centrospheres with astral rays surrounding them (fig. E, 1, ¢). The relatively
huge nuclei contain several nucleoli and are transversed by filaments, plasmo-
dendrites (fig. E, 1, plas.), which are the remains of the nuclear spindle fibers
formed by the division of the centrosphere or centrosome.

These peculiar structures are found in the sporocytes of all ages, but dis-
appear with the maturity of the spore. In the last sporocyte divisions the
centrospheres and achromatic figures disappear (figs. E, 2,4) and a simple type
of ‘‘ Haplomitose”’ results.

In this still incomplete study of Chatton interesting questions concerning
the complete stages of mitosis and nuclear development are raised, both in the
parasitic and in the free-living forms. The difference between the two types
may be due, as he suggests, to the influence of hypernutrition consequent on a
parasitic mode of life within the digestive canal of pelagic copepods. A com-
parison of free-living and parasitic forms elsewhere among the Protozoa out-
side of the Sporozoa, where free-living forms are not found, does not suggest
this as a probable solution. There are suggestions in some of Borgert’s figures
(1910, pl. 2, figs. 12-14) of an archoplasmic structure corresponding to spindle
and polar regions. It may well be that further studies on these forms, with
more critical cytological differentiation, will demonstrate the presence of such
structures and reveal a closer similarity between the processes in the free-living
and parasitic forms.

PusuLes.—A well developed pusule apparatus is usually present in all the
dinoflagellates. It consists essentially of a sacklike vacuole connected with
the exterior by a slender canal opening into a flagellar pore. The fluid con-
tained within it has a delicate rose or pale salmon pink color. The exact
relations of the flagella and their blepharoplasts to the walls of the canal are
uncertain. Their insertion seems to be a short distance below the opening of
the pore. Two pusules are usually present, one opening anteriorly into the
anterior flagellar pore, the other opening posteriorly into the posterior one.
These two pusules may occasionally be united by a slender canal, forming a
long channel opening at either end into a flagellar pore. In many species, par-
ticularly in the thecate forms, one or two branches or accessory pusules are
formed as offshoots from the main collecting pusule. These are more or less
temporary and not as constant in their occurrence as the main pusule.

In the thecate forms the pusules are usually relatively huge, often with
accessory branches. Their size and their pink color combine to make them the
most conspicuous features of many of the species. For this reason they at-
tracted the attention of earlier biologists, and their structure and homologies
were the subject of some speculation. Biitschli (1885) compared them to the
contractile vacuoles of other better known Protozoa, and in this he was followed
by Schiitt (1895) in his comprehensive discussion of the subject. The latter
investigator also pointed out the difference between the ordinary fluid vacuoles

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 23

that are usually present in the cytoplasm and the rather complicated pusule
apparatus. In the latter he distinguished four or more parts, including a sack
pusule, a collecting pusule, smaller daughter and accessory pusules in the sur-
rounding cytoplasm, with a pusule canal extending to the periphery of the body
from the main pusule. This entire structure he considered homologous with
the contractile vacuole of the ciliates and rhizopods.

A superficial examination reveals a general similarity in appearance between
the two structures. A closer examination, however, brings to light striking
differences. Unlike contractile vacuoles, these pusules possess a distinct
envelope or membrane, and contractions have never been observed.

This structure, moreover, has been shown by Kofoid’s work (1909) on
Peridinium steini to be connected directly with the intake of fluid into the body,
and not, as might be expected from the function of similar organelles in the
ciliates, as a collecting pusule for the discharge outward of fluids within the
body. The actual process of filling up from the surrounding medium has been
observed by us in some species of Gymnodinium, and in these cases did not occur
gradually but with a sudden inrush that immediately inflated the pusule. The
varying sizes and degree of development of these structures are dependent upon
the periodicity of their functioning, and this evidently accounts for their
presence in one individual and absence in another of the same species.

The process is essentially as follows: The fluid is taken in at the pores as
a result of the activity of the flagella, particularly of the waves of contraction
of the transverse flagellum, which tends to carry a current of water along the
girdle to its proximal end and thence down the coneavity of the ventral area,
thus bathing both pores. There may be a continuous, gradual accumulation of
fluid in the pusule or it may, by a sudden expansion, fill up with a rush. Vacuoles
similar in color and refractive index to the pusules soon begin to accumulate
in the plasma. In Peridiniwm steini, where this process was followed contin-
uously for nearly five hours (Kofoid, 1909), minute vacuoles appeared in a
layer around the sides of the pusule, followed shortly by larger vacuoles in the
surrounding plasma. ‘These collected in the peripheral zone, the outer border
of which began to shrink away from the thecal wall, the space thus left vacant
being filled with a fluid of the same rosy tinge as that found in the pusules and
vacuoles. This fluid seems to be discharged from the surface, probably by
osmosis.

Various stages of this process may be seen in our figures of the Gymnodi-
nioidae, suggesting the similarity of their functioning with that of the pusules
in the thecate forms. In Gyrodinium capsulatum the final stage of the process
is in progress (pl. 5, fig. 54), with the vacuoles collected at the surface ready to
discharge their contents into the surrounding water. In some cases the plasma
is rather densely filled with these vacuoles (pl. 7, fig. 74), while in other cases
the vacuoles are entirely absent. The huge size of the pusules in some indi-
viduals (pl. 5, fig. 57) and their entire absence in others suggests a periodicity

24 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

in their movements, though data on this point are entirely lacking. In some
cases they are bilobed (pl. 10, fig. 108; pl. 12, fig. 132) and in others the two
pores are connected by slender canals. The latter condition may possibly be a
remnant of the ingestion area, by means of which a large food mass has been
taken into the body. This condition is more frequently found in the more highly
specialized forms, to wit, in Cochlodinium, Pouchetia, and Erythropsis.

The pusule apparatus of the dinoflagellates usually reaches its greatest de-
velopment in the thecate forms, where daughter and accessory pusules are
formed (Schiitt, 1892; Kofoid, 1909), often of considerable complexity, and of
relatively huge size. They occur in species possessing chromatophores, though
their greatest development is reached where these organelles are entirely lacking.
No solid contents have been observed in the pusules or in the vacuoles formed
from them. The connection of these cell organs with the kind of nutrition
existing in the absence of chromatophores and the fact that their greatest de-
velopment exists in the forms whose theca of discrete plates would materially
interfere with the ingestion of solid food strongly point to a saprophytic mode
of nutrition in zones of decaying plankton. These facts also lead to the con-
clusion that the pusules, at least the anterior one, function as a cytopharynx
for the intake of fluids and probably also of food particles into the body. The
possibility of food vacuoles and food balls being formed in connection with the,
pusules is not excluded. The canal frequently found connecting the anterior
and posterior pusules (pl. 7, fig. 76) suggests this possibility, since it probably
represents the remnant of an ingestion area which has included the entire inter-
cingular area of the suleus. As has been pointed out in a previous paragraph,
it is evident from the size of the ingested organisms sometimes found in the
cytoplasm that the entire area of the intercingular sulcus must take part in the
process of ingestion. The channel connecting the two pores, lying at the prox-
imal and distal ends of this area respectively, would then probably persist as
the internal remnant of its previous expansion, during which it functioned as
the mouth of the organism.

OceLLi.—In the ocellus of the Pouchetiidae we find one of the most highly
specialized organelles among the Protozoa. Among the dinoflagellates it is
confined exclusively to this family, a similar structure not being present in
any other group. The more primitive red eyespot, or stigma, of fresh-water
Gymnodinium is hardly the equivalent of the ocellus.

The ocellate members of the Dinoflagellata were first observed by Pouchet,
who figured several species as members of the genus Gymnodinium in a series
of papers from 1883 to 1887. The ‘‘organe oculaire,’’ as he termed this peculiar
structure in the forms he observed, he described as a refractive, hyaline body
with one end buried ina mass of dark pigment. He also advanced the suggestion
that it probably functioned as a light-perceiving organ.

It was not, however, until the publication of Schttt’s monograph (1895)
that any adequate description or figures of the ocellus were presented. He

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA

bo
On

observed it in four species of Pouchetia, P. juno, P. rosea, P. fusus, and P.
compacta, and also in two species of Hrythropsis, FE. cochlea and E. cornuta,
though these two species he placed in the genus Pouchetia. Noting the advanced
degree of development of this peculiar structure, he formed the genus Pouchetia
for the ocellate dinoflagellates and placed therein all of the ocellate species
described earlier by Pouchet.

Schutt distinguished two types of ocelli, one with brownish black pigment,
as in P. schuetti (P. rosea Schiitt), the other with reddish black pigment, as
in P. fusus. The relation of these two colors, red and brown or black, in a
single pigment mass he did not observe. The lens he described as composed of
a single part, as in P. cochlea, or of several smaller moieties, as in P. schuetti.

Hertwig (1884) gave a fairly accurate account of the eyespot in Erythropsis
agtlis, describing its component parts as lens and pigment mass. Fauré-Fremiet
in 1914 gave a fuller account of the structure of this organelle in the genus
Erythropsis than had yet been attempted for any of the ocellate dinoflagellates.

The various points in which these descriptions differ from our own will be
noted as we continue our discussion of this structure.

The ocellus of the Pouchetiidae is composed of two distinct parts, a refrac-
tive, hyaline, sometimes spherical lens (fig. RR, 1), and a surrounding pigment
mass or melanosome (fig. RR, mel.). The lens or cristalline body of Pouchet
varies in shape in the different species. In its more highly integrated form it
is usually spheroidal in shape, clear and colorless and often asymmetrically
laminated. This stage is reached in many of the species of the genus Erythropsis
(pl. 12, figs. 129, 133), as well as in a few species of Pouchetia (pl. 11, fig. 118).
In some eases, where distinct lamellae are not seen, its optical properties produce
a play of colors not unlike that of a soap bubble (pl. 10, figs. 131, 134). In
other species the shape may vary to an elongate form, more or less irregular in
outline (pl. 6, fig. 61; pl. 11, fig. 126).

On cytolysis of the body the lens persists and when found free in the water
it presents a colorless appearance. In the living organism it often reflects
some tints of the surrounding cytoplasm (pl. 8, fig. 87) when partly buried
within it. or it may show only a few of the prismatic colors when its position is
protuberant above the cytoplasm, as in Hrythropsis pavillardi and E. cornuta
(pl. 12, figs. 133, 129).

The size and shape of the lens is not always easy to determine, since it is
more or less covered by the melanosome. <A certain amount of correlation be-
tween the size of the organism and the size of its ocellus is found in nearly all
the members of the group. Pouchetia parva, one of the smallest species in the
Pouchetiidae, has a length of 31“ for the body and a diameter of about 7» for
its ocellus. This is the smallest lens found in any species. The ratio between
the size of the body and of the lens is greater here, however, than the ratio found
in any other species. Thus in Hrythropsis cornuta (fig. SS, 1) the lens has a
diameter of 22” while the body has a length of 101”. In the largest species of

bo
or)

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

the group, Erythropsis cochlea (fig. SS, 7), the diameter of the lens is only
16 while the length of the body is 1314. In Pouchetia polyphemus (fig. OO, 11)
the ratio between the length of body and that of the lens shows the greatest
divergence, the former being about 104 and the latter 84. In P. purpwrescens
also this same divergence exists, though to a less extent, the length of the body
being 58 and that of the lens about 7.54. In most of the other species, however,
a closer correlation is found between the relative lengths of body and lens.

The size of the melanosome in relation to that of the lens is variable, due
largely, perhaps, to the amoeboid character of the pigment. In most species
it seems to be nearly equal to the lens in size, though probably not actually so,
since the lens is usually partly buried within its substance. In a few species,
notably in Nematodinium torpedo (fig. NN, 3), the melanosome has a relatively
minute size. In Hrythropsis cornuta (fig. RR, 1), on the other hand, the mela-
nosome has a size equal to several times that of the lens.

The simplest form of the melanosome is seen in Protopsis neapolitana
(pl. 9, fig. 96), where its relative size is also less than that of any other species
except in Nematodinium torpedo. Here it is a loose aggregate of black pig-
ment granules massed together at the anterior end of the lens, and apparently
lacking the central core. A still looser aggregation of pigment is found in
Pouchetia poucheti (pl. 11, fig. 125), but in this species the relative mass and
size of the discrete particles of pigment have become much greater.

The melanosome throughout the entire group is mobile to the extent of
moving freely around the lens, though no evidence of its movement to another
part of the body has ever been observed. While under observation the pigment
will spread over the face of the lens so that the latter is almost entirely obscured
(pl. 12, fig. 130), or will recede until it embraces only the base of the lens (pl. 12,
fig. 131). In some species amoeboid movements are noticeable, long pseudo-
podia being thrown out, sometimes around the lens (pl. 8, fig. 87), or away from
the lens into the surrounding cytoplasm (pl. 11, figs. 121, 126; pl. 12, fig. 127).
In many individuals while under observation this movement was continued so
that no two camera sketches, made at short intervals of time, gave the same
outlines for this remarkable organelle.

The center of the more highly integrated melanosome is occupied by a core
of highly colored pigment (fig. RR, core). This is usually red, often brilliant
in the more highly specialized forms (pl. 12, fig. 129) and light in tone in some
of the others (pl. 11, figs. 118, 119). It apparently is not amoeboid, but seems
to be connected with the base of the lens and forms the center or core around
which the black pigment wraps itself. The character of its connection with
the lens has not been clear in our material. At the time of cytolvsis of the
body the ocellus is usually the last part of the organism to disappear. The
core then separates itself from both the lens and the black pigment and appears
as a red subspheroidal body, which gradually wastes away without imparting
its own tint to the surrounding water (figs. TT, 4-8). The black pigment also

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA

bo
-

rounds up into one or more spheroidal masses and undergoes the same fate.
In one individual of Erythropsis extrudens observed the complete disappear-
ance of the ocellus required twenty minutes from the time cytolysis began, the
lens being the last part of the structure to dissolve.

Fauré-Fremiet (1914) has found that under the action of dilute acetic acid
the pigment of the melanosome is transformed into a multitude of small globules
of which part are brown and part are red. He evidently did not observe the
red central core of the melanosome so prominent in some of our own forms
(pl. 12, figs. 131, 134), though less noticeable in others (pl. 12, figs. 127, 129).
The action of the acetic acid on the red pigment of the core explains the
presence of the red granules in his figure of the melanosome thus treated.
Schiitt (1895) also failed to differentiate these two parts of the melanosome.

Various stages of integration of the ocellus are found within the group.
The simplest form of the lens presented is that of separate, loosely aggregated,
hyaline spheres, with scattered pigment granules partly surrounding them
(pl. 11, fig. 125). From this simple condition a process of integration is clearly
evident within the ocellate group, whereby the scattered pigment spherules are
combined into a compact mass closely enveloping the base of the lens, with a
correlated combination of separate spheres into a single, spheroidal lens, the
greatest development of which is perhaps that of Hrythropsis cornuta (pl. 12,
fig. 129), or EF. pavillardi (pl. 12, fig. 133). Various stages of this process
may be seen in the Pouchetidae, beginning probably with the genus Protopsis
(fig. LL), though phases of the diffuse, less integrated types may also be found
in Pouchetia (fig. PP, 4). In Protopsis neapolitana (fig. LL, 2) the mela-
nosome is composed of relatively few pigment granules with a large spheroidal
lens. A simpler condition is found in P. nigra (fig. LL, 1), where the lens also
presents the diffuse type, being composed of several small spheroidal bodies.

In Nematodinium partitum the ocellus is diffuse in structure (fig. NN, 4),
while in N. torpedo (fig. NN, 3) and N. armatum (fig. NN, 1) it presents a
progressive integration both in the lens and in the melanosome.

Ocelli of the diffuse type are found in Pouchetia poucheti (fig. PP, 4) and
P. maxima (fig. OO, 2), while most of the other species of that genus present
a more or less well integrated type of structure. The extreme development of
the amoeboid character of the melanosome is found in P. subnigra (fig. OO, 6)
and in P. alba (fig. PP, 8), where diffuse strands of black pigment wander out
through the cytoplasm. It is probable that the melanosome throughout the
entire group possesses this characteristic property of amoeboid movement in
varying degrees, as does the pigment found generally in the Gymnodinioidae.

The position of the ocellus is such as to receive the stimulus of light as the
animal rotates in forward locomotion. It seems to be fairly constant in most
of the members of the Pouchetiidae in its relation to the girdle and sulcus.
In the genera Protopsis, Nematodinium, and Pouchetia it is usually found in
the posterior half of the body, at the left of the intercingular sulcus and anterior

)

28 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

to the posterior junction of girdle and sulcus (figs. LL-PP). A few exceptions
to this may be found. In Nematodinium armatum (figs. NN, 1, 2) it is located
slightly posterior to the distal junction of the girdle and sulcus, as also in
N. partitum (fig. NN, 4). In Pouchetia purpurescens (fig. OO, 7) the ocellus
is located on the right side of the intercingular sulcus instead of the left when
viewed from the ventral face. This species and Protopsis neapolitana (fig.
LL, 2) are the only ones in which this organelle is thus located in the morpho-
logical right side of the body, instead of the left as in the other species. Owing
to the torsion of the body and the varying positions from which it may be
viewed, as well as its great transparency, this relation of ocellus and sulcus is
often hard to determine. It is easily the most conspicuous part of the body
and tends to obscure other structures lying near it. When the same organism
is viewed at several angles, however, it is quite evident that the ocellus is
situated on the morphologically left side of the body.

The orientation of the ocellus is also fairly constant throughout the group,
with the lens anteriorly placed with respect to the melanosome. <A few ex-
ceptions to this are found. In Protopsis neapolitana (fig. LL, 2) the mela-
nosome is anterior, with the axis of the ocellus as a whole lying at an angle of
about 45°with the main axis of the body. This is the only instance of this
apparent anteroposterior reversal of the usual relations of the lens and mela-
nosome to be found in the group.

A position in which the axis of the ocellus forms a right angle with the main
axis of the body is more frequently met, as in the species of Nematodinium
(fig. NN), Pouchetia purpurescens, and P. maxima (figs. OO, 7, 2). Nearly
every gradation from this horizontal position of the axis to a vertical one is to
be found among the species of Pouchetia (figs. OO, PP).

In the genus Hrythropsis fewer variations are found. The ocellus is in all
cases premedian and protuberant. One species only, EL. hispida (fig. SS, 2),
lacks the anteroposterior orientation of the ocellus to any marked degree. Here
the two structures he side by side, with the axis passing through both parts,
thus taking a horizontal position. In the remaining species the ocellus is
directed anteriorly. In LH. extrudens (fig. SS, 11) the amoeboid melanosome
at times nearly covers the lens, thus obscuring these relations. In the con-
tracted state, however, the axis showed only a small change from a vertical
position (fig. TT, 3).

Of the finer structure and constitution of the ocellus very little indeed is
known. Fauré-Fremiet (1914) found that the lens was not acted upon by
solvents for oil, such as alcohol and acetone. In alcoholic solution of iodine
it became yellow. In our own material we found that it is the last part of the
body to disappear in cytolysis, twenty minutes being required in one case for
its dissolution in sea water.

The melanosome, at least the part outside of the core, is evidently similar
in its constitution to the pigment that is frequently met with in other parts of
the body. This is most clearly seen in the diffuse type of melanosome where

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 29

the pigment may be more or less broken up and scattered through the cytoplasm
(pl. 11, figs. 121, 125; pl. 8, fig. 84). Its wandering movements are also char-
acteristic of cytoplasmic pigment.

This connection between the pigment of the melanosome and the pigment
scattered through the cytoplasm receives some confirmation in observations
made by Fauré-Fremiet (1914) on Erythropsis pavillardi. The cytoplasm of
the form he was working with was of diffuse rose color. Upon the addition of
dilute acetone or weak acetic acid to the organism the color was concentrated
in clusters of small red globules. The action of acetic acid on the melanosome
caused its breaking up into small red and brown granules, belonging respec-
tively to the outer dark pigment and to the core. The red granules presented
a similar appearance to that of the ‘‘erythrosomes”’ or precipitated color of the
cytoplasm.

Fauré-Fremiect’s observations also indicate that the pigment composing the
core of the melanosome is similar to that found in the cytoplasm. Thus far
we have found no evidence in our own work to show that it possesses the mobility
characteristic of the outer part of the melanosome. At the time of cytolysis
it separates from the melanin as a spheroidal mass which may break up into
two parts (fig. TT, 7). Under the action of the sea water it slowly dissolves,
as does the remainder of the ocellus.

The behavior of this organelle at the time of division is totally unknown.
In Protopsis ochrea (fig. LL, 4) Wright (1907) has figured a division stage in
which the separation of the two zooids has not yet taken place. The ocellus
as well as the girdles are fully formed in both daughter organisms. One large
body is present in the cytoplasm, but whether this is the still undivided nucleus
he does not state. It is probably a vacuole, as this stage of formation of the
anatomical features of the body would indicate the completion of division of
the nucleus. No hint is given as to the mode of formation of the ocelli. Division
stages of the ocellate dinoflagellates have been entirely absent from our own
material unfortunately, hence we can throw no lght upon this subject.

The function of this remarkable addition to the structural characteristics
of these flagellates is problematical. The reactions of these organisms to light
and other stimuli are almost entirely unknown, due to the rarity of the organ-
isms and to the difficulties of preserving them under conditions suitable for
experimental observation. This organelle is apparently structurally adapted
for and may be functionally efficient as a light-perceiving organ, though whether
actually so remains to be determined by experiment.

Nemarocysts.—Of all the organelles of the dinoflagellates two stand out
distinctly as metazoan in their type of structure. These are the nematocysts
and the ocelli. The latter structures are peculiar to the dinoflagellates alone,
while the former have a wider distribution in the Protozoa, being found
throughout the Cnidosporidia and in at least one species in the Ciliata, P'ron-
tonia leucas. In the Dinoflagellata they are found in two genera, Polykrikos
and Nematodinium (Pouchetia armata Dogiel).

30 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

These organelles were first figured by Biitschli (1873) as ‘‘ Nesselkapseln,”’
a term also used by Bergh (1881) in describing the same structures in Poly-
krikos auricularia (P. schwartzi). Pouchet (1887) figured them as nematocysts
without, however, giving the details of their structure, as both Biitschli and
Bergh had done. Fauré-Fremiet (1913a, b) was the first one to attempt a more
critical analysis of the origin and nature of these peculiar organelles. He was
followed by Chatton (1914c), who figured an elaborate stage of cyclical devel-
opment, markedly different from that outlined by Fauré-Fremiet. A further
analysis of these schemes of development will be given after the minute structure
of these organelles has been described.

o> SL
ae

Fig. F. Polykrikos Bitschli, and its nematocysts. 1. P. kofoidi (Kofoid). X 500. Individual of four
zooids. After Kofoid (1907). 2. Nematocyst. X 1550. 3. Exploded nematocyst. X 1148. 4. P. schwartzi
Bitschli. 500. Abbreviations: ant. p., anterior pore; cap., head of nematocyst; epi., epicone; fil., filament;
gir., girdle; hyp., hypocone; long. fl., longitudinal flagella; n., nuclei; post. p., posterior pore; sty., stylet; sulc.,
suleus; tr. fl., transverse flagella.

The structure of the nematocysts of both Polykrikos and Nematodinium
is practically identical. The matured organ is found lying naked in the
plasma (pl. 11, fig. 122), without any special plasmatic membrane or structure
surrounding it, or any differentiated protoplasmic nidus in which it originates,
or any external plasmatic structure which might function as a enidocil. The
position of the nematocysts in the body of the dinoflagellate is not constant.
They may be found in all parts, though perhaps most frequently in the right
half of the body. Their orientation is also subject to great variations, with no
apparent relation to the surface of the body. Chatton (1914c) found that the
greater number were oriented with the pole of devagination turned towards
the surface of the body. In our own material this orientation seems no more

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 31

frequent than positions in which the pole of devagination is turned away from
the surface.

The matured organ has a length varying from 5 to 22” in the two genera.
In Polykrikos the average length is slightly greater than in the smaller species
of Nematodinium. In two species, N. torpedo and N. partitum, of the latter
genus the nematocysts range in length from 5r to 84, while those of N. armatwm,
with its much greater size of body, range from 14” to 22, a size comparable
with that of the organelles in Polykrikos.

The shape of the nematocyst is slender oval (fig. F, 2), surmounted by a
eaplike portion at the broader end. It consists of an external capsule (cap.)
of considerable rigidity, which Chatton regards as chitinous in its nature. Be-
ginning at the base of the caplike portion in the interior of the capsule is an
introverted sacklike extension (int.), which may reach to near the middle of
the capsule. This is continuous with the sides of the capsule as may be seen
in the exploded nematocyst (fig. F, 3, cnt.), in which this portion is everted
and thrown forward. To this structure Chatton has given the name ampulla
(ampoule).

Arising from the bottom of the interior of the introvert or ampulla is a
small cone-shaped thickening from the apex of which a slender stylet (sty.)
extends forward with a length nearly equal to that of the introvert, ending free
in the cavity. At the base of the introvert, opposite the origin of the stylet,
the thickening is continued into two lobelike bodies (/.) from the point of inter-
section of which springs a slender filament (/i/.) of considerable length, prob-
ably continuous with the walls of the capsule, the spiral coils of which fill the
posterior portion of the cavity. The exact relation of this filament to the stylet
is hard to determine. In the figures of both Bitschh and Bergh the stylet
functions as the base of the filament when the latter has been discharged from
the capsule. In Fauré-Fremiet’s figure the stylet remains within the introvert,
or rather is thrown backward after the discharge of the nematocyst. Chatton,
however, finds that the role of the stylet is that of an organ for piercing the
operculum at the time of discharge and is not directly connected with the fila-
ment, which passes through the thickened portion of the introvert at the base
of the stylet (fig. G), and is thrown off after the discharge of the nematocyst.

At the anterior end, surmounting the caplike head, is a minute operculum
(oper.) which marks the point of emergence of the stylet in the discharge of
the nematocyst.

No evidence is forthcoming regarding the normal discharge of these
organelles. When the body wall is ruptured and the nematocysts come in con-
tact with the sea water the discharge is usually instantaneous in the case of the
fully matured organelles. The addition of weak acetic acid, formalin or alcohol
will also cause a discharge. This process requires but a small fraction of a
second for its accomplishment, hence the details of it are difficult to observe
and conflicting reports as to the manner in which it takes place have resulted.

32 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Fauré-Fremiet (1913) described the discharge of the nematocysts as a rup-
ture of the extreme anterior end of the capsule, with an eversion of the introvert
and a rapid unrolling of the filament. Chatton has given a much fuller de-
scription of this process and one that differs in some essential details from
our own. According to his interpretation, the filament is not an integral part
of the structure of the nematocyst, continuous at its base with the walls of the
introvert, but is a distinct structure. A the time of explosion the introvert is
forced outward, following a rupture of the extreme anterior end of the head
of the nematocyst, and the filament is thrown out as a simple unrolling. He
figures no process at its posterior end by which its entire escape from the
nematocyst may be prevented.

In these structures, which are similar in practically every detail to the
nematocysts of the Coelenterata (fig. H, 3), a similarity in their explosive action
is to be expected. That this similarity exists would seem to be borne out by
certain features in their structure and in the appearance of the exploded
organelle. In the hydroids additional structures, as short spines, are often
present within the coiled filament. In the exploded cell these are found on the
outer part of the filament, leaving no doubt as to the fact of its eversion as a
tube at the time of discharge (fig. H, 4). In the dinoflagellates no such strue-
tures exist, hence, as the actual process cannot be followed with the eye, the

manner of it must be inferred by analogy and by the appearances of the
nematocysts both before and after discharge.

Our own interpretation of the explosion of the nematocysts is as follows:
Contact of the anterior end or head of the nematocyst with an appropriate
stimulus, such as sea water, causes its rupture with explosive abruptness, and
the introvert is thrown out. The ruptured membrane remains like a collar
(fig. F, 3) around the basal portion of the introvert in its new position
(fig. F. 3, int.). As this latter structure is everted the stylet and thickened
basal portion (sty.) occupy the extreme anterior end of the nematocyst.
Simultaneously with this outward projection of the introvert the filament is
thrown out (fig. F, 3, fil.) as an everted long slender tube. In this position it
is found to be continuous with the anterior end of the nematocyst (fig. F, 3).

The filament is a slender, double-contoured thread, the tubular nature of
which is hard to demonstrate. That this is its structure would seem evident
from its appearance at the time of explosion of the nematocyst, and by analogy
with similar organs in the Cnidosporidia (Doflein, 1911) and in the hydroids
(Toppe, 1910) (fig. H). After explosion it is connected and apparently con-
tinuous with the walls of the nematocyst at the extreme anterior end of this
structure. This is also shown in Chatton’s figures, one of which is reproduced
in our figure G, 10.

As has already been pointed out, Chatton does not figure any mechanism
by means of which the filament retains its relation with the nematocyst after
its explosion. A slender thread which has no organic connection with the

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 33

capsule would be thrown beyond its confines completely at the time of explosion,
which does not seem to be the case in any of Chatton’s figures. On the con-
trary, the extreme posterior end of the filament remains connected with the
extreme anterior end of the nematocyst in all cases (fig. G, 10), a fact that
would point to an intimate relation between the two structures. It seems prob-
able, therefore, that the filament in the nematocysts of the dinoflagellates has a
tubelike structure and is everted at the time of discharge of the nematocyst,
as in the case of the Cnidosporidia and Coelenterata (figs. H, 4, 5).

Fig. G. Development of the nematocysts of Polykrikos. After Chatton (1914c, pl. 9, figs. 2, 4-7, 10-12,
text figs. 6, 7). 1. Mature nematocyst with its enidoplaste attached. 2. Cnidoplaste detached with differen-
tiation beginning at anterior end. 3. Cnidoplaste with the introvert and stylet developing. 4. Body of enido-
plaste dissolving, leaving vacuole around it. 5. Further stage of the same, changing of enidoplaste into
enidogene. 6. Cnidogene stage, introvert and flagellum suspended in vacuole, sphere forming anteriorly which
is future cnidoplaste. 7. Further development of enidogene. Body of nematocyst forming in vacuole. 8.
Cnidogene developed into young nematocyst. 9. Further development of the same. 10. Exploded nematocyst
with stylet thrown off. xX ?

Chatton figures cases in which the nematocysts have been caught, as it were,
in the act of exploding, with the filament partly within and partly without the
capsule. This appearance is not inconsistent with our explanation of the pro-
cess as that of an eversion of a slender tube, as may be seen by partly with-
drawing the finger of a glove that has been turned inward. <A point will be
reached where the finger extends some distance on each side of its point of
insertion, as does the filament in his figures (1914c).

34 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Another point somewhat unconvincing in Chatton’s work is the role he has
attributed to the stylet. This he figures as a slender rod, slightly conical, with
the base wider than the apex (fig. G@). This shape is constant in all his figures
showing the stylet in the still unexploded nematocyst. After the explosion
has taken place its position in the center of the thickened portion of the introvert
is occupied by the filament. Near at hand, as though pushed out of position
by the filament, is a rod (fig. G, 10) differing in length and thickness from the
stylets which he has figured in the unexploded nematocysts. In our own
material (fig. F) the base of the filament after it has been discharged shows a
slight enlargement comparable with the appearance of the stylet in the unex-
ploded capsule. It seems probable, therefore, that here, as in the nematocysts
of the coelenterates, the stylet functions as the base of the extruded filament.

The development of these interesting organelles has also proved to be a
puzzling question, the solution of which has been greatly advanced by the re-
searches of Chatton (1914c). Fauré-Fremiet (1913) has offered a scheme of
development of the nematocysts from the small refractive granules common
in the cytoplasm. He presents no stages, however, between the small round
granules and the elongate body of the young nematocyst. These refractive
granules and small globules are common throughout the dinoflagellates gener-
ally, and since nematocysts are not common elsewhere more evidence is required
before they can be considered part of the development of these peculiar organs.

Chatton (1914c) offers another type of development which is cyclical in
character and of a considerable degree of complexity (fig. G). It consists of
three distinct stages, the first of which is the ‘‘cnidoplaste”’ (figs. G, 1-5), which
appears to arise from an organ resembling the centrosome. The cnidoplast
arises by a process of ‘‘autogenese’’ from the mature nematocyst. Part of this
process is shown in figures G, 6, 7, in the body forming at the anterior end of
the developing nematocyst. The cenidoplast is not enclosed in a chitinous cap-
sule and deliquesces readily in sea water. It goes through a process of devel-
opment by which the anterior end is transformed into a new structure, the
‘‘enidogene,’’ and the remainder of the body dissolves, its place being occupied
by a large vacuole (figs. G, 2-6). The cnidogene gradually develops into the
finished nematocyst. Chitinization of the body of the future nematocyst or
cnidocyst takes place in this vacuole while further development of the internal
structure of the capsule progresses (figs. G, 7-9). This results in the pro-
duction of the filament and the introvert or ampulla, and the cnidogene becomes
the mature nematocyst (fig. G, 9).

The number of mature nematocysts in the body of both Polykrikos and
Nematodinium varies in different individuals. In our own material of
Polykrikos the number has run from one or two less than the number of zooids
to twice the number of zooids of the body. Chatton has found that variations
may exist in the number of young forms or ‘‘cnidoplastes’’ (fig. G, 2), and
also in the number of mature nematocysts. In the secondary stage of their

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 35

development, the ‘‘enidogene”’ (fig. G, 6), he states, however, that the number is
constant and equal to the number of zooids of the body, and also that they are
metamerically arranged. Thus he figures (1910c, pl. 9, fig. 1) an individual of
eight zooids, each one of which contains a single ‘‘cnidogene,’’ centrally located
and oriented at an angle of about 45° from the longitudinal. The excess of
cnidoplasts formed are ejected from the body or dissolution takes place in situ.

This metamerism of the nematocysts is not shown in our own material nor
in the figures of other investigators, including Chatton’s figures of the mature
organelles. Its existence is thus apparently limited to this single stage of its
development.

It is thus seen that the exact origin of these structures still remains a doubt-
ful point, as does also their fate after the completion of the development of a
new set of organelles in the body. Chatton has suggested that the old nemato-
cysts are dissolved in the cytoplasm, and in proof of this figures a colored re-
fractive body frequently seen by him in Polykrikos (1910c, fig. 15, pl. 9). A
comparison of his figure with some of the cell inclusions in other species of
the Gymnodinioidae as shown in our own material (pl. 4, fig. 46; pl. 5, fig. 52)
shows that a closely similar structure is frequently present in other forms where
nematocysts do not occur, and lessens the probability of this being a disinte-
grative phase of these organelles.

CHAPTER III

GENERAL MORPHOLOGY: CYTOPLASMIC DIFFERENTIATION,
COLORATION, SURFACE DIFFERENTIATION

CYTOPLASMIC DIFFERENTIATION.—The tribe Gymnodinioidae presents both
extremes of cytoplasmic complexity found within the Flagellata, its lower forms
having the simplicity of structure found in the lower flagellates, and its more
highly specialized ones being exceeded in complexity only by the Trichonym-
phidae. In most of the species no distinct ectoplasmic differentiation can be
detected, beyond the presence of a thin periplast surrounding the body (figs.
X, CC). Varying degrees of differentiation leading up from this simple type
may be found with its highest development shown in the subgenus Pachydinium
of the genus Gymnodinium (fig. AA).

A distinct ectoplasm is present in this subgenus showing a degree of special-
ization reached elsewhere only by the Ciliata. This, as appears in Gymnodinium
pachydermatum (fig. AA, 5), consists of a relatively wide, clear, homogeneous,
double-contoured zone surrounding the endoplasm. Superimposed upon this
zone is an outer, alveolar layer, somewhat wider than the inner zone of homo-
genous ectoplasm. The outer facets of the alveoli are rounded and give to the
surface of the body a roughened, irregular contour. The alveoli are filled with
a clear homogeneous fluid of the same consistency as that found in the inner
zone of ectoplasm.

Correlated with this specialization of the ectoplasm is a relative complexity
of endoplasm shown in the presence of radial rodlets, vacuoles, oil droplets and
refractive granules. In some species the radial rodlets seem to occupy definite
places in the plasma and are probably intimately related to the metabolic
activity of the organism. They may be lacking in a few individuals and present
in others of the same species. Their usual location is near the anterior pore
and leading out towards the periphery of the body. They may sometimes be
observed streaming out from the pusule (fig. V).

In many other species showing a lack of ectoplasmic differentiation a zone
of short rodlets is often present in the peripheral region, closely packed together
and at right angles to the surface (fig. CC, 7). In end view these appear like
small vacuoles. These apparently have the same structure and greenish color
as the longer, centrally located ones, and evidently subserve the same or similar
purposes in the life economy of the organism. They are probably connected
with a saprophytic type of nutrition, since they are never present in forms
possessing chromatophores. They are also absent generally in the more highly
specialized members of the Gymnodinioidae, such as Cochlodiniwm, and the
Pouchetiidae, where nutrition is probably holozoic throughout.

[36]

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 37

These rodlets or rhabdosomes, as they have been called by Schiitt (1895),
are constantly present in the different individuals of many species, while in
other species they may be present in a few individuals and absent in others.
With the cytolysis of the body these rodlets melt away as do the fluid-filled
vacuoles, indicating a similarity in their structure. We have, therefore, con-
fined the term rhabdosome to those structures which have a greater perma-
nency, as in the long slender rhabdosomes constantly present in the genus T'oro-
dinium (fig. IT), and which do not deliquesce so readily as do the ordinary
vacuoles of the evtoplasm.

The endoplasm is usually visibly granular, but in the genus HKrythropsis
and in a few species in other genera this granular appearance is lacking, the
body presenting a hyaline, almost glassy texture that persists in Hrythropsis
until cytolysis of the body occurs.

CoLoraTIon.—The pelagic dinoflagellates are remarkable for their diversity
of coloration and for a brillancy and delicacy of tone which give to the minute
transparent body a beauty that is almost impossible of analysis and equally
difficult to reproduce. In comparatively few species is the color confined to a
single tint except in those forms having chromatophores or colored pigment.
The usual condition shows a background of soft pearl grey shot through with
one dominant color, intermingled with broken flashes of one, often two or more,
contrasting colors, the entire combination producing a rich effect impossible
of adequate reproduction.

The color may be resident in chromatophores (pl. 1, figs. 1, 4), vellow,
vellow ochre or greenish, or in pigment granules (pl. 6, figs. 65, 67, 69), or it may
by diffusion be a component part of the cytoplasm itself, with no evidence what-
ever of localization in even minute particles (pl. 6, figs. 63, 68). <A relatively
greater number of thecate forms than naked dinoflagellates possess chromato-
phores. In case of naked dinoflagellates the chromatophores are confined to
the simpler, more generalized species, namely, Amphidinium (fig. U) and the
lower forms of Gymnodinium (fig. X) and Gyrodinium (fig. CC). In the more
highly specialized groups of the Gymnodiniioidae they are almost entirely
absent, as in Pouchetia (pl. 11) and Erythropsis (pl. 12).

Nearly the whole range of colors of the spectrum are to be found within the
species of the different members of the Gymnodiniidae. It is noteworthy also
that a certain amount of correlation may be found in the group between the
coloration and the amount of specialization attained within the group. In
Amphidinium the predominating colors are green and yellow (pl. 1, figs. 1, 4,
11), correlated with a relatively greater number of chromatophore-bearing
forms. The colors of the red end of the spectrum are entirely unknown in this
genus.

In the genus Gymnodinium its most specialized species, such as G'. pachy-
dermatum, G. dogieli, and G. amphora (pl. 3, figs. 32, 34, 26), show a type of
differentiation which throws them outside the line of evolution which produces

38 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

the higher or more advanced genera, these having evidently come from the
simpler, more generalized, but rather highly colored species, as G. violescens
(pl. 6, fig. 69), G. rubricauda, and G. rubrum (pl. 8, figs. 88, 86).

In the genus Gyrodinium the type of structural specialization has not gone
beyond that attained by the genus Cochlodinium. It has no species which show
a great degree of specialization peculiar to that genus alone, such a speciali-
zation as is found in some species of the genus Gymnodinium. Some of its
most highly colored species, as Gyrodinium virgatum (pl. 10, fig. 112), are
among its most advanced species leading on to the next genus, Cochlodinium.

In the genus Cochlodinium, as in Gymnodinium, the species showing the
most brilliant colors, especially those near the red end of the spectrum, fall
within its more generalized group, that is, without the extreme torsion of the
body. These species are C. miniatum (pl. 10, fig. 107), which is closely allied to
Gyrodinium, Cochlodinium constrictum, and C. rosaceum (pl. 8, fig. 85), the
latter species probably representing the closest approach to the type of structure
of the Pouchetiidae found within the genus.

In the Pouchetiidae a yellow color is only rarely met with, the predominating
tones being those near the red end of the spectrum and in the green section
(pl. 8, figs. 84, 87, 89, 90; pl. 11), combined with melanin appearing almost for
the first time in the ocellus of this family. In the most highly specialized
member of the family, Hrythropsis, vellow is unknown, while red pigment in
some form is found in nearly every species in combination with melanin in
the ocellus (pl. 12), or localized in the cytoplasm as in one species, #. scarlatina
(pl. 12, fig. 128).

The presence of melanin within the group, while less common, also bears
the same relation to the amount of specialization, that is, it is found within the
line of advance from the simpler to the more complex members of the group.
It is present in Gyrodinium spumantia (pl. 7, fig. 72) and Cochlodinium atro-
maculatum (pl. 7, fig. 71) alone among the members of the family Gymnodi-
niidae. In the family Pouchetiidae melanin is found in all the species, occa-
sionally scattered through the cytoplasm (pl. 11, fig. 119), but more commonly
confined to the melanosome (pl. 11, figs. 118, 122).

It thus appears that an advance in specialization within the group as a whole
runs from the simpler types, with a predominant yellow or green color, as in
Amphidinium, through the more brilliantly colored species of Gymnodinium,
Gyrodinium, and Cochlodinium, to the Pouchetiidae, with the predominating
colors in most of the species near the red end of the spectrum. Specialization
within the genus, however, below the Pouchetiidae, is usually found to occur in
those species which are not highly colored, where this specialization leads to
one side of the main advance from one genus to the next, as in Gymnodinium
pachydermatum and its allied species.

Within the Pouchetiidae, however, the progressive structural specialization
within the group leads from the species with faintly tinged bluish green to the

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 39

red and black colors, the advance being shown in the increasing specialization
of the ocellus, sulcus, and girdle. In the genus Pouchetia the species displaying
some tones of red, as P. compacta, P. voracis, P. rubescens (pl. 8, figs. 89. 90),
and P. maculata, with the group of purplish species, P. purpurata, P. purpur-
escens, and P. schuetti, are its most highly specialized members, as shown in
the degree of integration of the ocellus and the complexity of the girdle and
sulcus.

A few exceptions to this general tendency may be found, as in P. violescens
(pl. 11, fig. 118) and P. juno, which are also highly specialized species in struc-
ture, though not in color. A few exceptions also may be found in the other
genera. The preponderance of evidence, however, suggests that these lines of
structural evolution are, in the main, correlated with progressive movement in
coloration towards the red end of the spectrum throughout the larger groups
of the Gymnodinioidae.

The fresh-water species of the group, confined to the genera Amphidinium,
Gymnodinium, and Gyrodinium, are markedly less brilliant in their color than
are the pelagic forms. They are colorless, as in Gymnodinium helveticum and
Gyrodinium hyalinum, or with dull green or yellow ochre chromatophores, as
in most of the other species found in that habitat. The only apparent exception
to this conclusion is found in the presence of a minute red eyespot in the mid-
ventral suleal area. This may be homologous with the pigment formation
common in the pelagic species, but not with the ocellus as a whole, though it
may be represented in the red core of the latter organ. It is rather a structure
comparable to the eyespot or stigma of Huglena and other fresh-water flagellates.

Pigment in some form is common in many of the members of the Gymno-
dinioidae, and frequently becomes the most conspicuous feature of the organism,
as in Gymnodinium lineopunicum (pl. 6, fig. 65), with its markedly motile
pomegranate purple pigment. This pigment, as frequently seen in other species
also, is almost constantly changing its position under apparently normal condi-
tions, with the organism still active and no indications of the approach of
cytolysis. So constantly was this change taking place in the individual shown
in plate 6, figure 65, that a complete camera sketch of its appearance at one
time could not be obtained.

A more striking instance of the motility of pigment in these forms is shown
in Gyrodinium ochraceum (pl. 7, figs. 76, 82). In examining a number of
individuals of this species a great difference was noted in the pigment formation
among them. In some specimens the pigment would be diffused uniformly
throughout the body in minute grains. In others these would be localized into
larger granules, as in figure 76. Still others would exhibit various stages be-
tween that condition and the band of pigment wound spirally about the body
(pl. 7, fig. 82). These appearances were puzzling in the extreme. It was not,
however, until a single individual was held under observation for a considerable
length of time that an explanation was found.

40 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

When first observed this individual presented an appearance like that shown
in figure 76, with the pigment in scattered granules. In a short time a change
began to take place, the pigment moving slowly into the region of the girdle
and collecting into a wide mass or band which extended some distance on both
sides of the girdle (pl. 7, fig. 82). Though normally pigment occupies a position
close to the periphery of the body, yet this band formation took place inside
of the girdle without extending into the lips of the girdle, which were clear.
The remainder of the cytoplasm was apparently free from pigment also. Soon
after this formation was completed further changes began. Small nodules ap-
peared along the margin of the band, like outpushings from the main mass.
These were pinched off and began to move out into the cytoplasm. This process
continued until the entire band had become dissipated, the granules moving
away until at the end of the period of observation the individual again presented
the same appearance as when first noted (pl. 7, fig. 76).

Indications of this same motility of the pigment are to be seen in the red
pigment in Gyrodinium corallinum (pl. 10, fig. 117). The position of this in
the cytoplasm varies greatly in different individuals as well as in successive
periods of time in the same specimen. One peculiarity of the movement of
coloring matter or pigment in species which have a striate surface may be ob-
served in this form. This is the marked tendency of such material to follow
the lines of striae on the surface, where it may collect in small granules or
become massed in long bands. Gyrodinium fulvum (pl. 7, fig. 70) and more
strikingly. G. virgatum (pl. 10, fig. 112), exhibit this same peculiarity.

Another marked feature of the behavior of pigment in these forms is the
tendency to collect in the epicone, espectally near the apex, leaving the hypocone
relatively free, though usually not entirely so, from the colored granules. In
Gyrodinium maculatum (pl. 6, fig. 62) the abundant, violet-colored pigment is
densely massed in the epicone, so that under the low powers of the microscope
this part of the body appears almost black, while the smaller granules in the
hypocone are sufficient only to give it a violet tinge.

A few exceptions to this general rule are to be met with. In Gyrodinium
postmaculatum (pl. 6, fig. 64) the color is massed at the antapical end, leaving
the anterior end of the body free from agglomerated masses of color. The
same condition is found in G. rubricaudatum (pl. 10, fig. 116). In Erythropsis
scarlatina (pl. 12, fig. 128) still another modification is found. In the anterior
part of the organism the pigment is confined more or less closely to the periphery
of the body, while in the centroposterior part it occupies the interior of the
body with amoeboid ramifications extending through the cytoplasm.

It is not uncommon to find, on the approach of cytolysis, that the color which
has before been completely diffused through the cytoplasm becomes localized
or condensed into granules, the erythrosomes of Fauré-Fremiet (1914). This
same condition may be produced by the addition of dilute acetic acid, as Fauré-
Fremiet has shown for the rose-colored specimen of Hrythropsis pavillardi.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 41

This appearance may also be produced by lack of oxygen or other adverse con-
ditions consequent on a small supply of fluid under a cover slip during micro-
scopical examination. In Peridinium crassipes the bright coral red color may
be observed in its condensation under the microscope. This will continue until
the cytoplasm is colorless and filled with red balls of a considerable size. The
addition of fresh sea water to the surrounding medium will, in some cases where
the adverse conditions have not killed the organism, result in a diffusion of
the color with an almost complete disappearance of the red granules in the
-cytoplasm.

In the ease of Gyrodinium ochraceum, recorded above, the condensation and
subsequent diffusion of the pigment is evidently not caused by adverse condi-
tions in the surrounding medium since individuals showing all stages of the
process may be found in the same haul. It may be due to physiological condi-
tions in the organism itself or to the reacton to stimuli resulting from its own
activities or to light, or other factors of its surroundings. The relatively rapid
changes under the microscope are probably due to the progressive changes
taking place in the surrounding medium.

The localization of pigments near the girdle, sulcus, longitudinal striae and
at the apices is suggestive that internal oxidation processes resulting from
contraction, and from other internal responses to stimuli, are potent factors in
determining the origin, location, and movements of these products of the living
substance.

SurRFACE DIFFERENTIATION.—The typical naked dinoflagellate differs but
little, if at all, in its ectoplasmic structure from the ordinary flagellate. A
differentiated ectoplasm, as distinct from the endoplasm, is only rarely met with
beyond the production of a thin periplast covering the body. This is thin and
elastic and allows for considerable metabolic changes of the body form (fig. A),
yet is firm enough to preserve a remarkable similarity in shape throughout the
individuals of any given species. To such changes some areas of the body are
more susceptible than others, as in the antapical region and the posteroventral
surface near the suleus (fig. T). These areas of great susceptibility are un-
doubtedly correlated with the function of these portions of the body, the antap-
ical region serving as a vent for the ejection of unused or waste material from
the body and the suleus for the ingestion of food.

The periplast may be marked by lines, ridges or furrows of varying degrees
of development. Striae are usually confined to the outermost border of the
periplast, but occasionally may be deeper seated and may be indicative of a
fundamental organization of the protoplasm, as shown by the linear arrange-
ment of pigment (figs. DD, 9, 21). These surface markings are in all cases
longitudinal, extending from the girdle to the apices, diminishing in number
near the poles and often fading out entirely in the apical regions. Different
kinds of surface markings may be present in one species, as furrows and linear
lines or dots (fig. W, 3).

42 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

In the tribe Peridinioidae, as in the Prorocentridae, the surface is still
further elaborated by the development of a theca of discrete plates, often of a
perfection of form and finish and of a beauty of design surpassed by no other
similar group of structures. This exoskeleton exhibits a tendency to show longi-
tudinal linear markings not unlike the linear striae of the periplast of the un-
armored dinoflagellates in number, location, and distribution.

CHAPTER IV

PHYSIOLOGY: “RED WATER,” NUTRITION, REACTIONS TO
STIMULI, LUMINESCENCE

In the Protozoa we find all life processes reduced to their simplest expres-
sion. This makes for simplicity of function, but since these functions are all
carried on within the compass of a single microscopic cell it often conduces
also to complexity of organization. As not infrequently happens, a single group
of organisms may present a wide range of structural differentiations, with con-
sequent modifications of physiological activities.

This is particularly true of the Flagellata, which present the elementary
characteristics of both plant and animal organization. The dividing line be-
tween these two types of organization and the resulting physiological activities
which mark the plant and animal kingdoms cannot be drawn with certainty
between orders, families, genera or even species among certain Protozoa, since
in some groups even related species may respectively exhibit the two types of
organization. Such a group is the Dinoflagellata. In the members of this
group we find forms of the simplest type of organization, as well as some which
exhibit the highest degree of specialization, in some features, to be found within
the Protozoa, and we find also types of nutrition ranging from the typically
plant method through saprophytic to the typically animal mode of food-getting.
This condition makes these organisms of peculiar interest to the biologist be-
cause of this intimate interrelation of such diverse functions.

The physiological activities of this group have, however, received but little
attention. A few scattered references to the subject may be found in the liter-
ature, but the data given on such constituent parts of the body as starch grains,
amyloid bodies, etc., have usually not been based on definite experimentation
and therefore are inconclusive. No work has thus far been done along this line
by the present authors, hence this subject can only be touched upon lightly,
with tentative conclusions which must await definite experimentation for
confirmation.

The dinoflagellates probably rank next to the diatoms in their abundance
in the sea and in their importance as a food supply for the smaller plankton
life which feeds upon the great oceanic meadows. Hxaminations of the stomach
contents of sardines and other small fish reveal the fact that a very large per-
centage of the food used by these animals consists at times of dinoflagellates.
In many parts of the ocean and at some seasons of the year these flagellates
far outrank the diatoms in abundance, and become the dominant forms for
longer or shorter periods of time. At such times they may become a menace
to the slow-moving or bottom-living animals. The unusual amount of oil and

[43]

44 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

other products secreted by them and released in great quantities through the
rapid decay of the organisms, as is often the case in an outbreak of ‘‘red water”’
along the California coast, proves overwhelming to those animals which are
not able to escape from the infested area (Kofoid, 1911). These animals, which
include such forms as the holothurians, sipunculids, mollusks, the sting ray
(Urolophus hallert) and guitar fish (Rhinobatis productis), die in great num-
bers and are cast up by the tide upon the beaches.

In the more common occurrences of small patches of red or yellow water
which may persist on the surface of the ocean for a few days and then disap-
pear as mysteriously as they came are to be found evidences of the great plas-
ticity of these organisms, and their physiological reactions to slight changes in
the chemical content of the oceanic waters. These reactions and interrelations
are obscure, and but little can be done besides pointing out a few of the lines
along which further evidence must be looked for.

“Rep Warer.’’—The occurrence of isolated patches of discolored water at
the surface of the ocean is frequently observed during the summer months
along the shores of southern California. These areas vary in color from a
slight grevish turbidity of the water to a decided yellow, red or dark brown
color. The extent of the water thus affected may be limited to a few hundred
yards, such as occurred during July, 1914, at La Jolla, and in July and August,
1917, from Long Beach to Santa Barbara, California, or it may extend for a
hundred miles or more along the coast, as in the outbreak of red water in the
same region in August, 1907 (Kofoid, 1911). These discolored areas are usually
found near shore with a seaward extension of one-half to three miles.

The length of time during which these areas may persist ranges from a
few days to several weeks. Torrey (1902) records the appearance of red water
from July 7 to September 1, 1902, from the region of Santa Barbara to San
Diego.

This discoloration has been popularly attributed to submarine earthquakes,
landslides, or the presence of sulphur or phosphorus discharged from submarine
mineral springs in the water. It is, however, caused by the sudden appearance
of vast multitudes of dinoflagellates in the surface plankton, and may be due
to the sudden and periodic enrichment under favoring conditions of temper-
ature and light of the coastal waters by the nitrogen-bearing upwellings common
along the shores of that part of California.

The presence of such vast quantities of these minute organisms within a
limited space results in the death of countless myriads of them, the ensuing
decay producing a nauseous and penetrating stench of a most disagreeable
nature. These products of decay are toxic to many marine organisms, which
die in great abundance and are stranded on the beach by the tide. The filtrating
action of the beach sands also results in the accumulation of vast quantities
of these organisms along the tide lines and the sands become foul with odors
of their decay.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 45

The species of dinoflagellate which has been found most frequently to be
the cause of the manifestation of red water is Gonyaulax polyhedra. During
the summer of 1914 an outbreak of ‘‘ yellow water’ occurred which lasted from
July 27 to August 6, caused by a small species of Gymnodinium, which is here
described as G. flavum. This was found to occur in small patches, the greenish
vellow color of which was very conspicuous on the crest of the breakers near
shore. A sharp line of demarcation separated these patches from the unin-
fected waters. Okamura (1916) found that areas of colored water in Yokohama
harbor, Japan, in June, 1910-1911, were due to the presence of Cochlodinium
catenatum. These were present in such vast quantities that the effect upon
the marine life in the waters was marked, many fish dying as a result.

Somewhat similar to these appearances of colored areas of sea water is the
occurrence of Amphidinium on the beach sands at Port Erin, Isle of Man, as
recorded by Herdman in a series of papers in 1911-1913. These were found
in such vast quantities that the sands were colored a greenish brown. They
occurred about or a little above the half-tide mark. These deposits were of a
varying size, one of the largest covering a continuous stretch of sand about
fifty yards long by five yards in breadth. They were visible for periods ranging
from a few days to a month, increasing or decreasing or even changing the
location according to the stages of the tide. More than one species of Amphi-
dinium was found to be present in these colored areas, the predominant one
being A. herdmani (A. operculatum).

Under ordinary circumstances no zone of decay is found in the beach sands,
since the adjustments of bacterial, plant, and animal life in this region are
such that reciprocal growth and decay preserve the balance of the arenaceous
habitat, as they do in the pelagic one, without marked localizations of regions
of fermentation and decay. That the diatoms play a part in these interchanges
and interrelationships within the arenaceous habitat is well known. The only
references, however, to the part that dinoflagellates may take therein are those
of Herdman, who followed for several years the recurrences of patches of
Amphidinium followed by nearly equal numbers of diatoms in the same region.
From April 7 to November 2, 1911, Amphidinium appeared thus four times.
This rhythmical occurrence of two different forms in the same territory is
strongly suggestive of the alternations that may sometimes be observed in
plants, one plant alternating with another in recurrent occupation of the same
region.

Nurtrition.—The subject of nutrition in the dinoflagellates is one fraught
with many misconceptions and inaccuracies, due to the imperfect knowledge of
the group. West (1916) in his recent book on the Algae in the series of Cam-
bridge Botanical Handbooks places the Dinoflagellata with the Algae, stating
that over 90 per cent of them are true vegetable organisms with holophytic
nutrition.

46 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

One cannot work with the marine unarmored Dinoflagellata for even a short
time without being struck by the fact that the majority of the individuals ob-
served show evidences of holozoic nutrition, in the Gymnodinioidae at least, and
that the number actually containing chromatophores is relatively small through-
out the entire Dinoflagellata. Contrary to West’s statement, it is probable that
a large number of them have not holophytic but saprophytic or holozoic nutri-
tion. It is notable also that a few forms, as Amphidinium steini, may possess
chromatophores and at the same time show the presence of foreign bodies in
the cytoplasm (Stein, 1858-59). This has been true in our own material also
(pl. 4, fig. 44; pl. 5, fig. 50), though the actual ingestion of foreign organisms
has not been observed.

The cell contents of an alga consist of nucleus, chromatophores, pyrenoids,
starch grains or related assimilates, and perhaps a few oil globules. On the
other hand, the presence of distinct chromatophores of the typical algal form
is a comparatively rare occurrence in the dinoflagellates, even in the thecate
forms, where the ingestion of solid particles of any considerable size would
appear to be a difficult if not impossible procedure. The evidences for holozoic
nutrition lie in the presence of food bodies, often of recognizable organisms,
within food vacuoles in the cytoplasm, and the accumulations of the products
of metabolism in the form of oil globules, vacuoles, refractive granules, and
rodlets in the central or peripheral plasma. These, correlated with the absence
of chromatophores, would seem to offer conclusive evidence of holozoic nutrition
in the greater number of species of the unarmored type.

The genus Amphidinium is probably more nearly holophytic throughout its
range than any other genus as a whole. A few apparent exceptions are found
here, however, as in A. stein’, mentioned above. Stein has figured this species
with definite organisms in the body as well as chromatophores, though the latter
are smaller than those in individuals without ingested food bodies. It may
be that this indicates a periodic recurrence or at least facultative occurrence
of both types of nutrition. Evidences of a similar condition may be noted in
A. scissum (pl. 2, fig. 22). <A. cucurbitella (pl. 1, fig. 6) shows undoubted
evidences of holozoic nutrition. Two large masses are present in the cytoplasm,
one surrounded by a water vacuole as though recently ingested. In A. cucurbita
(pl. 1. fig. 9) the body is filled with radial rodlets and large masses, one of which
hes in a vacuole, interspersed with refractive granules, the whole presenting
an appearance hardly compatible with holophytic nutrition. Other species in
this genus which show some slight evidences of holozoic nutrition are A. crassum
(fig. U, 18), A. sulcatum (fig. U, 10), and A. vasculum (pl. 4, fig. 36).

In the genus Gymnodinium a relatively smaller number of species occurs
which possess undoubted chromatophores. Most of these are found in the more
generalized group, the subgenus Gymnodinium strictu sensu. Here also, as in
Amphidinium, the two types of nutrition are occasionally found associated in
the same species, as in Gymnodinium fulgens (fig. X, 30), G. agile (pl. 3, fig.
31), and in G. herbacewm (pl. 4, fig. 44).

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 47

West (1916) concludes that the nutrition of the colored forms is holophytie.
One of the most highly colored species found in the Gymnodinoidae is seen in
Gymnodinium lineopunicum (pl. 6, fig. 65), in which the remains of an ingested
Pouchetia are found occupying the anterior part of the body. In G. violescens
(pl. 6, fig. 69) also food bodies are present, though not definitely recognizable
as distinct organisms. Other species in this group showing the same indications
are G. contractum (pl. 5, fig. 52), G. sulcatum (pl. 8, fig. 83), and G. rubricauda
(pl. 8, fig. 88), the first two of which contain bodies still surrounded by a
definite vacuole. In G. tncisum (pl. 3, fig. 27) the remains of a Pouchetia with
the ocellus still visible clearly indicate the origin of many such bodies in the
plasma of these forms as the partly digested remains of ingested organisms.
It is thus evident that color alone can not be taken as indicative of the type
of nutrition which may be possessed by the organism displaying it. Further
evidences of this will be found in the genera Cochlodiniwm and Pouchetia.

In the remaining species of Gymnodinium comprised in the subgenera,
Pachydinium and Lineadinium, the absence of chromatophores is quite general
and indicates saprophytic or holozoic nutrition for most if not all of these
species. In Gymnodinium helveticum (fig. Y, 11) Penard (1891, pl. 5, fig. 13)
has figured an ingested rhizopod, Difflugia arcula. For most of the species of
the subgenus Pachydinium (figs. Z, AA) nutrition seems to be holozoic. In
Gymnodinium lira (pl. 3, fig. 830) we find an unusual condition in the ingestion
of what appears to be a grain of sand, which fills a large part of the body.

Dogiel (1906) found food bodies present in both G. coeruleum and G. hete-
rostriatum (G. obtusum). In the latter species our own material has offered
abundant evidence of its preference for solid food.. Plate 5, figure 56, shows
such an one which had captured a Cochlodinium individual. Members of this
species were numerous in many hauls throughout the summer at La Jolla, and
in only a few cases was the body free from such ingested material. The size
of the ingested organism was often huge, and under the stress of conditions in
the microscopical field it would frequently be ejected from the body by a vent
at the antapex. During this process, which occupied but a moment, the entire
posterior end of the body was rent open, presenting a similar appearance to
that shown in Pouchetia maxima (pl. 6, fig. 61). This vent immediately began
to draw together and in a few minutes had completely disappeared, the body
resuming its normal outline at the antapex. The ingestion of these huge bodies
has not been observed, but it is probable that it takes place by an amoeboid-
engulfing action of the sulcal area similar to the process noted in other flagel-
lates, as in Tetratrichomonas prowazeki (Kofoid and Swezy, 1915).

In the genus Gyrodinium the number of species with chromatophores is
very small, both relatively and numerically. The same possibility of the union
of both holophytic and holozoic nutrition previously noted is suggested in
G. melo (pl. 5, fig. 50) with its green chromatophores and large food body.
G. intortum (fig. CC, 10), whose green color might indicate a vegetable method

48 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

of feeding, has ingested a dinoflagellate which still shows its characteristic
girdle.

In the species containing an abundance of yellow ochraceous pigment, as
in G. ochraceum and G. fulvwm, as well as those with red pigment, as G. coral-
linum, G. virgatum, and G. britannia, the cytoplasm is usually clear, with few
inclusions, and gives no evidences of the formation of starch granules or re-
lated products. Food bodies may be occasionally found in G@. corallinum as
well as in G. ochraceum, though most of the specimens of these species noted
present no clue to their manner of feeding. In G. virgatum (pl. 10, fig. 112)
the posterior end of the body is distorted, presenting the same appearance found
in Gymnodinium heterostriatum after the ejection of a food mass.

In another species, G. maculatum (pl. 6, fig. 62), also plentifully supplied
with pigment of a violet color, food bodies were occasionally found within the
cytoplasm, which, at other times, was remarkably clear and free from cell inclu-
sions of all kinds. It is probable, therefore, that these forms have a saprophytic
or holozoic mode of food-getting. The numbers of individuals of some of
these species that were observed, however, were too small to be conclusive on
this point.

We find in the members of the genus Cochlodinium evidences of holozoic
nutrition similar to those observed in the three preceding genera. One of the
most striking instances of this is that seen in Cochlodinium rosaceum (pl. 8,
fig. 85) with its ingested Pouchetia. This is one of many instances in which
members of the latter genus have been devoured by other dinoflagellates, and
might suggest its desirability as a choice article of food. It is, however,
probably no more frequently captured than are the members of the other genera,
but the latter quickly lose their characteristic features and become indistin-
guishable in a food vacuole. With Pouchetia, on the contrary, the ocellus re-
tains its characteristic appearance until final disintegration of the body, making
it easy to identify the generic, though not the specific, status of the digesting
food mass.

In the species Cochlodinium vinctum (pl. 2, fig. 15), of which a number of
individuals were examined, it was found that a large food body of similar
appearance was present in each specimen examined. This was located in the
anterodextral part of the body. It is a reniform, greenish or oil yellow, vacuo-
lated body with its surface covered with small, highly refractive spherules re-
sembling oil drops. These are arranged over the surface with considerable
regularity. Its center contains an elongated pinkish vacuole and in one instance
what appears to be a nucleus of the dinoflagellate type. Other bodies were
sometimes present in the cytoplasm.

In Nematodinium partitum (pl. 6, fig. 68) a species of Gymnodinium is
shown, with its girdle still intact. Other members of this genus also present
evidences of food masses within the plasma.

In Pouchetia we find the most striking instance presented in the group
thus far. One specimen of P. voracis was found with the theea of a Peridinium

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 49

partly crushed together within its body (fig. PP, 2). The contents had evi-
dently been digested and the remains were being forced to the posterior region
of the body preparatory to ejection when the Pouchetia escaped from the
cyst. The Peridinium here captured is a large species, the length of the body
equaling that of the organism which has devoured it, as may be seen from the
length of the half-shell which is visible in the figure.

Pouchetia, like the genus Erythropsis, has no species which possesses chro-
matophores. <A few of the species of the former and all the latter failed to
show the presence of food bodies in the cytoplasm. With the small number
of species and individuals observed, however, this is not conclusive evidence
as to its manner of food-taking. It is probable that nutrition is either sapro-
phytic or more probably holozoic in both genera.

The same conditions that have been observed in the forms discussed here-
with obtain in the other members of the Gymnodinioidae. One of the most
rapacious feeders is Noctiluca. This seems to devour indiscriminately any-
thing of an organic or even an inorganic nature that comes in its way; the
authors have observed on two occasions the presence of grains of sand within
it nearly as large as the body. Both these individuals were lying on the sub-
strate apparently unable to rise above it.

In this brief review of these forms it has been shown that there is an upward
progression from a chromatophore-bearing, holophytie type of nutrition in
Amphidinium, which has probably been carried over from the holophytic
cryptomonads, to a saprophytic and holozoic type in the more advanced mem-
bers of the group. In some species both types are intermingled, others are
more clearly marked off as having a single type of nutrition. The demarcation
between the saprophytic and holozoic types is still more difficult to define since
those belonging to the latter group resemble the saprophytic forms when food
bodies are not present. It is possible that all three types may be found in a
single individual.

The presence of pusules in these organisms is significant:in this connection.
The process of taking the surrounding medium into the body through the
pusules, its passage through the cytoplasm and escape at the surface is prob-
ably correlated with a saprophytic method of food-taking. The relatively huge
size of the pusule apparatus in the thecate forms may be due to the lack of free
access of the surrounding fluid to the cytoplasmic body. Many species of the
dinoflagellates are never captured in surface hauls, but are found within the
deeper layers of water, which are also the layers most rich in decaying plankton
and hence most suited to saprophytic organisms.

A fourth mode of food-getting is also present in this group, that is, the
parasitic type found in the Blastodiniidae. Some of these, as Blastodiniwm
pruvott (Chatton, 1906), may be only a commensal in the intestine of the host,
Paracalanus parvus, or they may be truly parasitic, as in Chytriodinium roseum,
which feeds upon the contents of the egg of a copepod (Doflein, 1911). Still

50 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

others are ectoparasitic, as Oodinium poucheti on Appendicularia (Pouchet,
1885a).

The dinoflagellates are thus found to have evolved all the types of nutrition
that are known in other groups of living organisms. The manner in which
this has taken place is difficult to conjecture, since the fact that all types may
be found in the same plankton haul, under precisely similar conditions, pre-
cludes an explanation of environmental changes or isolation as the determining
factor. Neither are there any evidences which would make sexual selection
responsible for the change. The factors which afford a plausible explanation
of these phenomena in the Metazoa are difficult to apply to these simply
organized creatures without apparent sexual differentiation or behavior.

The possible relation of the process of digestion and the color of the organ-
ism is shown in the characteristic color that is found in what appear to be food
balls in some species. In many cases these bodies vary in size and often in
position in individuals of the same species with relatively little variation in
color. These are evidently not secretions, such as starch grains, ete., but appear
to be food bodies in process of solution. The characteristic color for the species
may possibly be due to the specific chemical reactions of the digestive fluids,
and as such may vary but slightly for different members of the same species.

The presence of a definite mouth or cytostome in the Dinoflagellata is ob-
secured by the dislocation of the flagella from the functional anterior end of
the body and their migration to a midventral location. It is still more modified
and seemingly obliterated in many species by the separation of the two flagella
and the resulting presence of two distinct flagellar pores, the anterior one from
which the transverse flagellum takes its origin, and the posterior from which
the trailing, propelling flagellum emerges. Between these two lies the inter-
cingular part of the sulcus and from each of the pores a slender canal leads to
an expanded pusule. These pusules may have their deeper ends approximated
or even joined in a continuous cavity from pore to pore.

While no dinoflagellate has been seen by us to capture food with the lips
of the intercingular sulcus it appears from its relation to the pores and flagella
and its probable derivation from the cytostomal region of more primitive flagel-
lates that this region is the morphological equivalent of the mouth or cystostome
and functions as such in the capture of the relatively large organisms found
within its food vacuoles. The astonishing plasticity of the oral region observed
by us in some parasitic trichomonads, and reported by Rhodes (1920) in
Collodictyon, encourages us to hazard the inference that the intercingular sulcus
is correspondingly mobile and efficient as a food-capturing mechanism in the
unarmored dinoflagellates. From the evolutionary standpoint it has been one
of the most plastic parts of the organism and it is perhaps equally mobile in
the individual.

Reactions TO Strmvutt.—This is still an untouched field as far as the dino-
flagellates are concerned, as it is for the majority of Protozoa in general.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 51

Beyond the application of stimuli for the production of light by the organisms,
no laboratory experiments with them have been carried on by us. In their
reaction to light a few facts only have been brought forth.

One of the most interesting of these is that recorded by Herdman (1913)
for two species of Amphidinium. He had noted, during a succession of years,
the rhythmic appearance of patches of these organisms on the beach sands at
Port Erin, Isle of Man. In addition to this rhythmic occurrence another
rhythm was observed in the appearance above, and disappearance below, the
surface of the sand; it was these latter movements that were investigated. It
was found that this was a direct response to environmental stimuli and could
be very fairly calculated from a knowledge of the actinic value of the light
and the condition of the tide. The optimum light was a diffused one, with an
avoidance of strong illumination. The organisms were also found to disappear
before the incoming tide reached them and to reappear as soon as the tide re-
ceded from their area. These two interacting stimuli, light and tide, produced
a daily and a fortnightly rhythm. If conditions were experimentally altered
a new rhythm intervened.

During the summer at La Jolla hauls were made at four-hour intervals
through the day and night from the surface of the water at the end of the pier
at the Biological Station. These were supplemented by hauls made at varying
distances of one to eleven miles offshore, both surface hauls and from a depth
of sixty or eighty meters to the surface. The latter were made only during
the day, usually about 8 o’clock in the morning, though this was not invariable.
These hauls were carefully examined and records made of the occurrence of
the dinoflagellates contained therein.

These records during the month of July for the collections at the pier show
only a slight variation in the number of species present at the different intervals
throughout the day, the smallest number being that for 4 a.m., the highest at
8a.m., with a slightly smaller percentage at 8 p.m. and 12 p.m. than for the 12 m.
and 4 p.m. records. These records are inconclusive owing to the amount of
foggy weather prevailing during that month. This was found to influence
materially the number of holozoic dinoflagellates (or those without chromato-
phores) appearing at the surface. Most of the forms possessing chromato-
phores, and therefore dependent upon sunlight, are found to be neritic or littoral
in their habitat, with a predominance of holozoic organisms in the strictly
pelagic plankton. As a result of this, surface hauls made during the day
contain the neritic forms and relatively few holozoie species.

In the hauls made farther offshore, where neritic influences were not so
potent, it was found that the surface hauls usually contained relatively few
forms, both as to species and as to individuals, while the deeper hauls made at
or very near the same place at approximately the same time were usually well
supplied with dinoflagellates.

These conditions indicate a negative heliotropism, with marked avoidance
of strong sunlight in many of the species at least.

On
bo

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

LUMINESCENCE.— One of the most strikingly familiar sights of the sea beach
at night during the warm months of the year is the display of phosphorescence
in the breakers. Many of the small plankton forms are capable of producing
this light, such as crustaceans, worms, and coelenterates, as well as some of the
bacteria. No inconsiderable part of it, however, is due to these minute dino-
flagellates. It is probable that the bacteria play little if any part in the ordi-
nary exhibitions of phosphorescence of the sea, since the light they produce is
a continuous one and not a sudden flash, such as may be observed in the breakers
or in the water elsewhere when it has been disturbed.

Noctiluca was the first one of the group which received recognition as a
light-producing organism, observations having been made on it as far back as
1717 (Dahlgren, 1915-16). Since that time casual notes and detailed studies
on this form have been numerous, as a result of its wide distribution, great
abundanee and relatively large size, combined with the brightness of the hght
which it produces. It is probable that other forms somewhat similar in struc-
ture to Noctiluca, as Leptodiscus and Craspedotella, are also luminescent, but
thus far no evidence has been brought forth to bear out this conclusion.

It was not until some time after these first observations made on Noctiluca
that the light-producing qualities of the remainder of the dinoflagellates were
noted. This was due to the work of Michaelis in 1830. He figured at least
nine species of Peridinium, Ceratium, and Prorocentrum, with a description
of the light produced by them. These observations were confirmed by later
investigators, but without the exactness of detail that has been given for
Noctiluca.

Among the Peridiniidae and Gymnodiniidae very many, if not most, of the
genera contain light-bearing species. Observations on these groups have been
almost wholly confined to the thecate forms, due to their greater abundance
and the comparative ease with which they may be studied. Those that have
received the most attention are Ceratium tripos, Gonyaulax polyhedra, Peri-
dinium bahamense, and a colonial species of Peridinium observed by Dahlgren
(1915-16) in the waters of the Delaware and Chesapeake bays.

Experiments made by us at the Biological Station at La Jolla, California,
have also been mainly on the thecate forms. The method of study has been
the isolation of individuals in a watch glass with a small amount of filtered
water, which has been examined both before and after the experiment to make
certain that no other organisms were present. These isolated individuals were
then tested by various stimuli, jarring the watch glass or adding fresh water,
alcohol, ether, or other chemicals in very dilute quantities. It was found in
this manner that nearly all the species of Peridinium, Ceratium, and Gonyaulax,
then common in the plankton hauls, were capable of producing light. Light
was never observed in a watch glass containing a single organism without the
application of stimuli, though it was abundantly exhibited in the glass dish
near by containing the usual plankton haul. This would indicate the necessity

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 53

for stimuli of some sort for the production of the light, whether through contact
with other organisms or débris, or through agitation of the water.

To determine the periodicity of the production of the light, watch glasses
containing a single individual, as well as finger bowls containing a quantity of
the plankton, were placed in the dark room and tested at various times during
the day. These were sometimes taken into the dark room during the day, or
as frequently were placed there on being brought in at the 12 and 4 o’clock
night hauls. They were thus kept continuously in the dark for twenty-four
hours. The results were invariably the same in both cases, that is, light ceased
to be produced with the early dawn and began again with the coming of late
dusk in the evening. No amount of stimulation was able to bring forth the
slightest response during the day. With the coming of dusk stimulation would
produce a few flashes at first, and with the deepening darkness the number of
these increased until the bowl would show its maximum illumination. The
reverse of this procedure took place with the coming of dawn.

The light given forth by these dinoflagellates is silvery white and lasts no
more than a single second. Dahlgren has noted another method of lghting,
which he calls the death glow or glow of exhaustion, caused by lifting Ceratiwm
out of the water on to the hand or a bit of clean cloth or paper. In these cases
the glow lasted from several seconds to several minutes. This probably explains
the phenomenon observed in the hauls that were made each night. When the
net was drawn up, rubbing it with the finger caused streaks of light which lasted
usually for a much greater length of time than the ordinary flash seen in the
water. This is probably produced by the organisms caught in the meshes of
the net and thus held captive. The amount of light seen in this way is much
greater than that produced at any one time in the jars containing the hauls.
The long-horned Ceratiwm and other forms would most easily become entangled
in the threads of the net, allowing the smaller, smoother forms, such as
Gymnodinium, to escape altogether.

During an outbreak of yellow water near the Biological Station, July 27 to
August 6, 1914, caused by the presence of enormous quantities of Gymnodinium
flavum (see p. 209), the breakers along the shore were brightly luminous. A
few forms of both Gonyaular and Noctiluca were found in the hauls, but not
in sufficient numbers to account for this display. At the height of the outbreak
Gymnodinium flavum was present almost to the exclusion of other forms. It
seems, therefore, certain that the phosphorescence observed was due to this
organism, though, unfortunately, no tests were made in the laboratory to confirm
this conclusion.

The very close similarity of structure between the naked and thecate dino-
flagellates leads to the belief that the capacities for luminescence in the two
groups are much the same, and that the ability to produce light is not confined
to a few species alone. In the tests that were made at La Jolla during the
summers of 1916 and 1917 it was evident that no single group of dinoflagellates

54 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

was present in sufficient quantity to account for the amount of light produced
at one time. On the contrary, it must have been the combined result of all the
groups, since many genera and species of dinoflagellates were abundant, often
to the exclusion of other known, light-producing organisms.

The probable seat of luminosity has vet to be determined. In Noctiluca
it is found as spots of light on the surface, which may be localized or may include
the entire periphery of the organism. The presence of oil globules or allied
substances is common throughout the dinoflagellates, especially near the surface,
and it is probable that the material from which luciferine is secreted is drawn
from these bodies. No observations have yet been made, however, upon the
condition of these before and after the exhibition of light.

CHAPTER V

COMPARATIVE ORGANOLOGY: OCELLI, PUSULES,
NEMATOCYSTS

In any group of organisms differentiation within the group comes about
through modifications of their characters more often than by the addition of
new ones. In the Protozoa, which in the number of individuals far exceeds
that of any other phylum, the number of structures upon which these changes
may be rung is exceedingly small in comparison with the Metazoa. To permit
the production of the vast number of different kinds of protozoan organisms,
then, modifications have appeared, manifold in variety, usually minute and often
obscure, vet making a grand total that gives to this group a diversity of form
and appearance as great as, if not greater, than may be found in any other
phylum.

Tn all this baffling array it is no small task to unravel the tangled lines of
growth and variations and place the fundamental structures in their proper
relationships. The task is often rendered further impossible by the lack of
adequate data and by misinterpretations of both form and function which ob-
secure much of the earlier literature. The work must of necessity, therefore,
be only fragmentary, providing a basis upon which future investigation may
place the growing structure.

The fundamental features of the Protozoa consist of motor organelles with
their related structures, organelles for food-getting, assimilation and excretion,
nuclei and skeletal modifications. Some of these structures, as external motor
organelles and nuclei, have less significance from the standpoint of comparative
morphology, especially of the smaller groups and of species, since their relations
and homologies are obvious and fundamental. The other structures of the
protozoan body are subject to greater modifications, and their interrelations
become increasingly complex as speciation progresses.

This is especially true of those organelles which, present in a simple or
modified form in the Protozoa, have been carried on into the Metazoa and find
there their highest development. Beyond the definite structures directly cor-
related with the functions pertaining to the comparatively simple type of organ-
ization found in the ordinary cell, structures of this type are not numerous,
and have always been the occasion for much skepticism. Among such struc-
tures may be mentioned the ocelli and nematocysts of the dinoflagellates, and
the nervous and muscular elements found throughout the Protozoa generally,
reaching their highest development in the group in the neuromotor apparatus
of the higher flagellates and ciliates. It is, however, in these fundamental types
of living organisms, with their vast periods of evolutionary development and

[55]

56 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

asexual—and possibly sexual—generations behind them, that the beginning of
many of the metazoan organs must be looked for and not in subsequent aggre-
gates of differentiated cells.

In no place is this obvious relation of the Protozoa and Metazoa more
strikingly illustrated than in nuclear conditions which obtain throughout the
two groups. The older method of beginning all cytological study of nuclear
phenomena with Ascaris, or other metazoan types of a relatively late period
of evolution, is an inversion of the natural order. Recent investigations are
continually bringing to hght knowledge of nuclear and mitotic phenomena in
the Protozoa, which may ultimately result in a considerable reorganization of
many of our present day concepts of these conditions in the Metazoa.

OceELLI1.—In the possession of a well developed eyespot or ocellus the
Pouchetiidae stand unique among the Protozoa. In its type of structure this
organ is distinctly metazoan in character, apart from the fact that it forms
only part of a single cell instead of being made up of a number of cells united
in specialized tissues. From the larger viewpoint of the body as an integrated
organism, and not as groups of cellular tissues, this aspect of its lack of cellular
organization is of relatively minor importance.

Schutt, in his monograph on Die Peridineen (1895), places the stigma, or
eyespot, as it is sometimes termed, of the fresh-water dinoflagellates, as in
Glenodinium cinctum, 1 the same category as the ocellus of Pouchetia, as did
Butschli (1885) in his earlier discussion of this subject. Later biologists, as
Lang (1901), Doflein (1911), and Liihe (1913), add to this category the stigma
of fresh-water flagellates, as in Huglena and Eudorina. The basis of these later
comparisons seems to lie in the early investigations of Francé (1893), which
have not, however, been confirmed by later investigators working on the same
forms.

Francé figured for Euglena, Eudorina, Pandorina, and Trachelomonas
stigmata of a peculiar type. In each of these flagellates this structure consisted
of a mass of red pigment imbedded within which were small spherical bodies.
These bodies varied in number from one to two or more in the different species.
They were spherical or ellipsoidal in shape and highly refractive. In Huglena
these bodies were composed of paramylum and in the Phytoflagellata of
amyvlum.

The later work of Wager (1899) and Hamburger (1911) on Euglena and
of Kofoid (1898, 1899) on Pleodorina and Platydorina cast considerable doubt
on the validity of Francé’s work. Both Wager and Hamburger found in
Euglena viridis that the stigma is composed of small red granules imbedded in
a protoplasmic layer. The stigma lies on the border of the cytopharynx in
close relation with a slight enlargement of the flagellum. No ‘‘erystallin’’ or
“lens bodies’? could be found in any of the material under examination. In
Pleodorina and Platydorina the stigmata are simple masses of pigment gran-
ules, with no differentiated structure. Other examples might be mentioned, but

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA

on
~

these will suffice to show that Francé’s work cannot be accepted without further
investigation and confirmation on this point.

The stigma of the fresh-water dinoflagellates, as in Glenodinium cinctum,
Gymnodinium paradoxum, and Gyrodinium hyalinum, is likewise a simple un-
differentiated mass of granular pigment, located in the ventral suleal area, near
the origin of the longitudinal flagellum. These structures seem to be homol-
ogous with the stigmata of the flagellates, apparently identical in structure and
probably in origin. The widespread occurrence of this organelle throughout
the fresh-water Flagellata would suggest a correlation between its development
and its environment, since it is rarely if ever present in the marine forms.

On the other hand, the entire absence of a stigma of this type in the simpler
dinoflagellates of oceanic waters would suggest the improbability of its forming
one of the developmental stages of an organelle which is found only in the
highly specialized pelagic species of the Pouchetiidae. No adequate evidence
is forthcoming to show the presence of intermediate stages between these two
types of structures.

These facts then point towards the conclusion that the ocelli of the dino-
flagellates is not a derivative of the stigma commonly present in the fresh-water
species of this group, as well as in other flagellates. Hvidence seems also to
point to a connection between scattered pigment occurring in many of the
marine species and the progressive formation of the melanosome of the Pouche-
tiidae. We have, therefore, confined the term stigma to the simple mass of
pigment granules present in the lower forms, and use the term ocellus for the
more highly specialized organelles of the Pouchetiidae.

In its structural efficiency, as found in Hrythropsis, it is probably fully equal
to the ocelli found in the medusae of the Hydrozoa, which may consist of a
cluster of pigmented cells or a cup of pigmented cells filled with a spherical
thickening of the cuticle to form a lens. The difference is here mainly one of
size, that of the medusa having several cells uniting to perform a function
which in Erythropsis is confined to parts of a single cell. The minute structure
of the lens and its exact relations to the melanosome have not been investigated
in the Pouchetiidae, beyond observations on the living organism. When this
has been done it may reveal structural similarities which will indicate more
clearly its relationships than can be shown with our present knowledge of this
organelle. That it is a light-receiving organ and a fairly efficient one the details
of its structure would indicate.

PusuLes.—The cytostomal area of the dinoflagellates is represented in the
suleus and the flagellar pores on the ventral surface, its internal extensions
taking the form of pusules. The reasons for these conclusions have been pointed
out elsewhere. The fundamental underlying organization is directly compar-
able with that of similar structures elsewhere in the Protozoa, and consists
essentially of a groove in the surface leading to the opening through the plasma.
Kach group of Protozoa in which this structure is found has its own peculiar

58 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

modifications of the fundamental type, such as membranellae and cilia in the
ciliates; and the modifications in the Dinoflagellata are no less peculiar and
typical.

The modifications characteristic of this group consist of two grooves at the
junction of which are located the openings into the pusules. The first of these
grooves is the transverse one or girdle, extending in a more or less spiral course
around the body (fig. B, gir.). Occupying the furrow of the girdle is the rela-
tively wide, ribbon-like flagellum. This is in constant motion with waves passing
from its proximal to or towards its distal end. This motion, combined with
the spiral course of the girdle, keeps a constant current of water passing over
the opening. The second furrow is longitudinal and joins the two ends of the
girdle. The flagellum which arises from the posterior pore and occupies the
posterior portion of the longitudinal groove or sulcus is threadlike, and hence
offers the least possible obstacle to the free movement of the current of water
down the sulcus. Both of these grooves are bordered by lips usually wide and
well developed. In the thecate forms these are still further marked off by
broad lists or fins. The relatively narrow opening or pore into the anterior
pusule lies at the anterior junction of the girdle and sulcus at the base of the
groove. The posterior pore lies near the distal junction. These pores are thus
located at the points which would give optimum conditions for their functioning
as cytostomal areas.

The anterior pusule is somewhat more prominent than the posterior one
and is probably the one in which the function most closely approximates that
of the cytopharynx of other groups or is most highly localized. Its close con-
nection with the anterior flagellum finds its parallel in the juxtaposition of
flagella and cytostome in the trichomonad flagellates (Kofoid and Swezy, 1915),
and more strikingly in Chilomonas paramecium, where the flagella emerge
directly from the cytostomal opening with their insertion near its base. The
same connection of flagellum and pusular opening is found also in the longi-
tudinal flagellum. The reason for this intimate connection is patently the need
of a propelling force to insure a constant current of water down the ventral
groove and over the openings. The constant wavelike motion of the transverse
flagellum, combined with the shape of the furrows, lends itself admirably to
this purpose.

The full homology of the cytostome of the simpler flagellates is, however,
to be found in the intercingular sulcus as a whole, and the two pores at the bases
of the two widely separated flagella are to be regarded as the anterior and
posterior ends respectively of the primitive cytostome shifted from its original
anterior location to the midventral region and stretched out longitudinally be-
tween the migrating flagella. It is twisted about the body in Gymnodinium
and Cochlodinium and may be extended anteriorly in the anterior limb or loop
of the sulcus towards the apex and posteriorly in the posterior limb towards
the antapex. It is improbable that these extensions have any share in cyto-
stomal functions of the intercingular sulcus, from which they take their origin.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 59

NeEMATocysts.—The nematocysts, like the ocelli of the dinoflagellates, are
among the most highly specialized organelles found in the Protozoa. Like
them also the nematocysts of Polykrikos and Nematodiniwm, similar in strue-
ture to the nematocysts of the Coelenterata, represent a type of specialization
that is metazoan in its character and occurence rather than protozoan.

The fact that these organelles are of rare occurrence in the Dinoflagellata
and are totally unknown in the remainder of the Mastigophora naturally raises
the query whether they may not be adventitious bodies, ingested either with
fragments of coelenterates as food, or after discharge into the water from some
coelenterate of the plankton. This suspicion of extraneous origin is heightened
by the fact that such cases are known in the Metazoa, as in the molluse Acolis,
in which the nematocysts are introduced into the body with its food (Grosvenor,
1903).

Several facts point towards the conclusion that the nematocysts of both
Polykrikos and Nematodinium are not adventitious bodies, but are normal
structures in the organisms in which they are found. First and foremost of
these is the fact that they occur in at least four different species, have been
found in every individual of these species thus far examined, and have not been
found in other forms feeding on the same plankton and often showing the same
kind of ingested organisms.

Fragments of coelenterates have not been observed as food particles nor
have free nematocysts been found in the plankton in which Polykrikos and
Nematodinium oecur. Contact with the sea water is usually sufficient to bring
about a discharge of the coiled filament of the nematocyst. The young stages
of the nematocysts deliquesce very rapidly in sea water on disintegration of
the body of Polykrikos. If they are adventitious it would be necessary for
them to resist the disintegration of the sea water prior to ingestion, provided
they were found free in the water. If ingested in coelenterate tissue the
matured nematocysts must endure ingestion without discharge. The structure
of the nematocysts is always constant, which might not be the case if they were
adventitious unless they were always derived from the same species of coelen-
terates. This would postulate a habit of selective feeding of which we have
not the slightest evidence. On the contrary, Polykrikos is omnivorous in its
feeding habits.

Fauré-Fremiet (1914) was the first investigator who attempted to solve the
mysteries of the development of these peculiar organelles, as also did Chatton
in a series of papers in 1914. The latter figured a cycle of development (fig. G)
which leaves many points still open to question. Both of these investigators
maintain as the result of their investigations the conclusion that these are
normal structures in Polykrikos, and not parasitic or adventitious in their
origin.

Fauré-Fremiet also pointed out the similarities between the nematocysts of
this genus and those found in Campanella umbellaria (Epistylis umbellaria).

60 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

These were described by Biitschli (1887-89) as occurring in pairs scattered
through the peripheral protoplasm.

The only other organelles of a similar nature occurring outside the Cnido-
sporidia are the trichocysts abundant in many species of the Ciliata. These
are not characteristic flagellate structures. Both Chatton (1914c) and Fauré-
Fremiet (1913) describe trichocysts in Polykrikos, however. These slender

Fig. H. Trichocysts and nematocysts. 1. Exploded trichocyst of Frontonia leucas Ehrbg. After Tonniges
(1914, pl. 18, fig. 1). X 1250. 2. Unexploded trichoeyst of same (pl. 18, fig. 4). X 1300. 3. Nematocyst of Hydra
attenuatus. After Toppe (1910, pl. 14, fig. 45c). X ? 4. Exploded nematoeyst of Hydra grisea. After Toppe
(1910, pl. 14, fig. 46b). X ? 5. Nematocysts of Myxobolus. After Doflein (1911, fig. 820 A). X ?

refractive bodies or rodlets, as we have termed them, are found throughout the
genera Gymnodinium and Gyrodinium as well as Polykrikos. They seem to
have no resemblance, either in structure or function, to the trichocysts of the
ciliates. No evidence is forthcoming to link them with the developing nemato-
eyst. Their general occurrence in many species of two genera which do not
possess nematocysts would preclude the possibility of so classifying them.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 61

A homology between the nematocysts of Polykrikos and Nematodinium and
the trichocysts of the ciliates appears also to be untenable, since the structure
of the two organelles differs so greatly. The origin of the latter structures is
still obseure, Maupas (1883) and Schewiakoff (1889) claiming an ectoplasmic
origin for them, while Brodsky (1909) found their origin in the endoplasm.
Their position is consistently in or closely abutting upon the ectoplasmic layer
in most if not all ciliates. Im Polykrikos, as in the genus Nematodiniwm, the
position of these organelles is not definitely localized. Neither can any definite
statement be made as to whether their origin is ectoplasmic or endoplasmic.
In the undischarged trichocysts of Frontonia leucas (fig. H, 2) a certain super-
ficial resemblance to the nematoeysts of Polykrikos is found. This resemblance
is entirely lost when the trichocyst is discharged (fig. H, 1). A long filament
is thrown out beyond the surface of the body, while the posterior portion of the
trichocyst also elongates, the whole structure becoming several times its original
length, diminishing in width at the same time.

In the Cnidosporidia the polar capsules, while resembling the nematocysts
of the dinoflagellates in general appearance, yet differ from them in their fixed
position, and in the fact that they are formed within a capsulogenous cell, from a
definite part of the developing sporocyst. In the spores of My«obolus (fig. H, 5)
the coiled thread of the nematocyst, lacking the differentiated introvert of those
in the dinoflagellates, is everted as a slender, tubular extension of the capsule.
This may be thrown completely out of the spore at the time of discharge
(Keysselitz, 1908).

In the nematocysts of the Coelenterata the anatomical features show only
a slight advance over those found in the dinoflagellates. The introvert may
be armed with spines variously arranged on the coiled filament when it is
everted (Toppe, 1910). In the resting stage the appearance of the whole
structure is not unlike that of the nematocysts of Polykrikos (fig. H, 3). The
accessory structures with which they are associated in the coelenterates, as the
enidoblast, form one of the chief differences between the two organs. The
question of homology between the two structures is one that needs more critical
data for its solution. The lack of a definite cnidoblast would not necessarily
point to an absence of homology, since that would probably be a secondary
acquisition, resulting from the multiplication of cells of the body and their
specialization, and unnecessary where one cell carries on all the functions of
the body. A certain amount of this specialization has taken place in the
Cnidosporidia, where the body of the developing somatella becomes divided
into two parts, each with a definite number of nuclei with definite functions
in the developing spore. Here also a further advance in the development
of the nematocysts has taken place in that they have acquired an enveloping
capsulogenous cell.

CHAPTER VI

LIFE CYCLES: EFFECTS OF PARASITISM ON LIFE CYCLE,
BINARY AND MULTIPLE FISSION, ENCYSTMENT, SEX

The question of polymorphism is one ever present in dealing not only with
the Protozoa but with most of the lower invertebrates as well. Protozoology
as a science is still so new and its accumulated data, though already vast and
daily increasing, so vague in outline and so interwoven with error, consequent
on its very newness, that this and related fundamental questions can only be
touched upon lightly, with the full knowledge that conclusions reached today
must wait upon further investigation for confirmation or refutation. That
this must be so does not conflict with the need for summarizing present achieve-
ment in any field, nor the formulation of conclusions drawn from existing data.
Indeed, these serve only to give a fresh impetus to investigation and to indicate
the lines along which important results may be found.

The possible connection between length of period of evolution and the
complexity of the life cycle resulting therefrom finds some striking confirmation
in the Protozoa as compared with the Metazoa, in which polymorphism tends
generally to disappear among the later evolved and more highly specialized
groups, except as related to sex. That other factors may enter into a consid-
eration of this problem does not alter the fact that polymorphism occurs in
inverse ratio to the length of time of evolution of the group, subject to secondary
modifications associated with adaptive processes as a result of parasitic and
social life and considerable changes of habitat.

In only a few forms among the Protozoa has a complete life cycle been
followed through from its initial zygote to the beginning of the next cycle. This
has resulted in the rather general conclusion that the life cycle is simple in all
but a few groups, the different stages being summarized in the two processes
of growth and binary fission. There is almost no positive evidence that this
is true for a single protozoan. On the contrary, it is becoming increasingly
evident that a much more complex state of affairs exists.

This question of polymorphism has a very direct bearing on any critical
study of the dinoflagellates, since one family of the Gymnodinioidae, the Pyro-
cystidae, has been formed for what later evidence clearly indicates are not
generically distinct organisms. This organism is the large, globular form,
Pyrocystis, which breaks up into sickle-shaped cysts (fig. I), the contents of
which divide again to form small, Gymnodinium-like flagellates, usually eight
in number. Evidence is accumulating, some of it still unpublished work by
the senior author, which shows that such a stage is an integral part of the life
cycle of genera as different as Gymnodinium and Gonyaulax. It is probable

[62]

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 63

that most. if not all, dinoflagellates pass through a ‘‘pyrocystis”’ stage or its
equivalent in their development.

Our knowledge of the development of the so-called Pyrocystis lunula
(Gymnodinium lunula) is still incomplete, but it serves to represent what we
already know of the life cycle of this group. In our somewhat diagrammatic
figure representing this cycle (fig. I) the beginning of the series is placed where
it very obviously does not belong. The beginning probably lies in the still
unbridged gap represented by the question mark. There is some evidence, very
slight to be sure, and needing further confirmation, that conjugation may occur
at this stage between the large globular organisms, and probably not in the
small flagellated forms, as might be expected, just escaped from the cyst
Gigs, 8).

This large spherical organism, without visible means of locomotion, first
attracted the attention of Murray on the voyage of the Challenger Expedition
of 1873-1876. His notes on it were published in his reports of the results of
the expedition in 1876 and 1885, with the name Pyrocystis suggested as an
appropriate designation. It has since that time been found to occur in all
oceanic waters where dinoflagellates have been studied, its distribution being
coextensive with that group.

Pouchet (18857) described a crescent-shaped cyst as “*Peridinium voisin de
Gymnodinium spirale,’ showing a single large Gymnodinium together with
other typical lanula cysts, one of which he figured with five smaller Gymno-
dinium-like flagellates contained within it. In Schiitt’s monograph on the
Peridiniales (1895) he figured as Gymnodinium lunula the crescent-shaped
cysts, and later (1896) changed their generic designation to Pyrocystis, as P.
lunula, thus recognizing their relation to the forms earlier described by Murray,
but as independent organisms, not as two phases of the same cycle. He divided
the development of Pyrocystis into two stages, the first the tetraspore stage in
which the cells are rounded to spindle-shaped, and the second or Gymnodinium-
like stage developing from the first.

The development of the spindle or crescent-shaped cysts from the large
spherical ones was not established until Dogiel (1906) and Apstein (1906)
published the results of their studies on the same forms. They followed the
development from the pyrocystis stage through the successive mitoses to the
formation of the small Gymnodinium and its escape from the crescent or second-
ary cyst. The account of the life cycle presented herewith is largely taken from
Dogiel’s admirable work, supplemented by the results of our own observations.

The change of the small Gymnodinium (fig. I, 11) to the large spherical
form has thus far escaped observation. This (fig. I, 1) is a naked form with-
out a cyst wall, though at first glance it might pass for an encysted individual.
The periplast is thick and closely adherent to the body. The nucleus is found
at one side close to the periphery, in a rather dense, granular mass of cytoplasm.
From this mass long streamers of cytoplasm run out, following the periphery

64 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

mainly and forming a loose network over the entire cell, the branches anasto-
mosing at various points. The interior of the cell is sometimes filled with a
single large vacuole, sometimes by several, with strands of protoplasm extending
through it from the main portion around the nucleus.

Fig. I

Fig. I. Life cycle of Gymnodinium lunula Schiitt. After Dogiel (1906, pl. 1) with some modifications.
Pyrocystis stage, 1-7. Gymnodinium stage, 8-11. 1. Large globular form. Resting spore? 2. Formation of
first cleavage nuclei. Protoplasmic body shrinking away from cyst wall. Primary cyst stage. 3. Second
cleavage with fourth division of nuclei completed. 4. Formation of crescent-shaped spores. Secondary cysts.
5. Single spore released from the cyst. 6. Beginning of division of the spore. 7. Completion of spore divisions
with the formation of eight Gymnodinium individuals. 8. G. lunula escaped from cyst. 9. Formation of ter-
tiary cyst. 10. Division of encysted individual. 11. Individual escaped from cyst. Encystment may take
place, repeating 9-11 many times before the next stage is begun. The change from 11 to 1 is unknown. X 330.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 65

With the formation of a cyst wall the body shrinks somewhat in size, leaving
a space between itself and the containing cyst (fig. I, 2). Division of the
nucleus takes place by a process of mitosis, and is usually repeated twice before
the body divides, so that four nuclei are present at the first division of the
cytoplasm, which results in the formation of four daughter cells. The nuclei
of these daughter cells divides again (fig. I, 3), producing eight nuclei or even
sixteen with a fourth division. With the division of the cytoplasm eight or
sixteen daughter cells are produced. These elongate and become encysted in
slender crescent-shaped, thick-walled cysts which are completely filled by the
body when first formed (fig. I, 4).

The mother or primary cyst ruptures soon after the completion of the for-
mation of the daughter or secondary cysts which float out freely into the water.
No evidence has been forthcoming to show that these secondary cysts are capable
of independent motion when the rupture of the primary cyst wall releases them.
On being set free the next stage in their development takes place. The cyto-
plasm of the encysted cell soon begins to shrink away from the wall (fig. I, 3),
concentrating at the center of the body around the nucleus, which divides
(fig. I, 6) once, twice or three times (fig. I, 7). The small bodies thus produced
develop into the typical Gymnodinium with a full complement of furrows and
flagella. These escape with the rupture of the cyst wall and form the motile
individuals of the cycle. They may become encysted (fig. I, 9) and divide
during the encysted state (fig. I, 10) or while free-moving. Simple binary
fission may be repeated many times, probably before the next stage is entered
upon, which results in the production of the phase shown in figure I.

Division of the contents of the secondary cysts into eight individuals is not
an invariable rule, apparently, since cysts are sometimes found containing two,
three, four, or six fully formed Gymnodinium individuals. This is probably
the result of the delay or omission of the second division or the division of one
or more secondarily formed nuclei. In some of the larger species (pl. 2, fig. 14)
a single individual may be formed within the cyst. The result of the process
outlined in figure I is normally the production of 64 or 128 individuals from
a single cell. The length of time necessary for the completion of this process
has not thus far been determined. Dogiel (1906) has estimated the length of
time for the development of the sixteen crescent-shaped cysts (fig. I, 4) from
an individual in which the first division has taken place as six hours. This
part of the life cycle is probably much longer than the part resulting in the
production of the large spherical form from the small Gymnodinium, since it
is relatively common, while the other stage has thus far eluded observation.

The crescent-shaped cysts have been found in several species of Gymnodi-
nium and also in Gonyaulax. One of these belongs to the larger species of
Gymnodinium as figured by Pouchet (1885a, pl. 2, fig. 4), with a single large
individual within the cyst. The form shown by Schiitt (1895, pl. 25, fig. 808,
reproduced in our text fig. Q, 1) as Gymnodinium lunula is obviously not related

66 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

to that species, its size being considerably greater and its form quite unlike the
typical lunula (fig. Q,5). His Gymnodinium fusus (= Gyrodinium falcatum),
shown in his figure 81, plate 25, is still another species, probably representing
a secondary cyst stage comparable to that of G. lunula. Dogiel (1906) has
figured one large encysted Gymnodinium in his figure 20, plate 1, which is also
not G. lunula, but quite evidently another distinct species.

These facts and our own observations demonstrate a wide prevalence of
these temporarily to more permanently encysted stages in the Gymnodiniidae,
and lead to the conclusion that a type of life history similar to that shown for

Fig. J. Blastodiniwm pruvoti Chatton. After Chatton (1906, figs. 1-5). 1. Paracalanus parvus (Claus),
containing three blastodiniums (par.) in the intestine. X 200. 2. Blastodinium pruvoti, showing circles of spines
around the body and two nuclei. X 400. 3. Division of the body into two parts, macrocyte (mac.) and microcyte
(mic.). Division is taking place in the latter. 4. Further development of both macrocyte and microcyte.
5. Gymnodinium-like form developed from the microcyte. X 500.

Gymnodinium lunula is to be expected for all the members of this group. It
is probably a much shorter stage and also much less frequent than that of the
vegetative motile phase, and hence is less common. The pyrocystis stage may
also be the resting period for the organism, and may require certain conditions
or seasons for its production. The whole question is still an open one, however,
and requires further investigation for the solution of its many difficulties.
EFFECTS OF PaRASITISM ON LiFE Cycie.—Still further complexity has been
introduced into the life cycle with the adoption of a parasitic mode of life by
one group of the Gymnodinioidae, the Blastodiniidae. Our knowledge of these

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 67

forms is mainly due to the investigations of Chatton, who published his results
in a series of papers between 1906 and 1912. Pouchet (1885a) had earlier de-
scribed Oodinium poucheti (=Gymnodinium pulvisculus) from Appendicu-
laria, and Dogiel (1906) added O. parasiticum (= Gymnodinium parasiticum)
from copepod eggs and Chytriodinium roseum (= Gymnodinium roseum) from
copepod or other crustacean eggs.

Fig. K. Development of Chytriodiniuwm roseum (Dogiel). After Dogiel (1906, pl. 2, figs. 26-35). 1. Small
amoeboid individual attached to crustacean egg. 2. Enlargement of parasite with third division of nucleus
in process. 3. Division of cytoplasm of parasite, contents of egg greatly diminished. 4. Further division of
C. rosewm with egg greatly shrunken. 5. Completion of first sporoblast divisions. This stage corresponds to
that of figures 9, 4, 6. Escaped sporoblast with contents dividing. 7, Further division of sporoblast. 8.
Gymnodinium-like individual escaped from cyst. 500.

The complete development of these interesting organisms still awaits more
thorough investigation. The contributions to their life history that have
already been made indicate a much higher degree of complexity than has been

68 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

attained by the free-living forms. The motile individual is a typical Gymno-
dinium-like flagellate of minute size usually and of simple organization (fig.
J,5). When it enters upon its parasitic career it loses its characteristic features.
The body becomes greatly enlarged, as in Blastodinium pruvoti (figs. J, 2-4)
and in this genus divides into macrocyte (mac.) and microcyte (mic.). These
follow individual lines of development that are still somewhat obscure, with the
final result, the production of a number of motile Gymnodinium-hke flagellates
(fig. J, 5).

A different type of life cycle is that described by Dogiel (1906) for
Chytriodinium roseum (= Gymnodinium roseum). The parasitic form as orig-
inally described consisted of two cells attached to each other, one minute, the
other huge (fig. K, 1). Part of the contents from the large cell passed into the
small one, which increased in size with a corresponding reduction in the bulk
of the other (figs. K, 2,3). This continued until but a small amount of cyto-
plasm remained of the larger cell in a somewhat collapsed cell membrane (fig.
Kk, 4). A later and probably more correct interpretation of these two cells
(Doflein, 1909; Chatton, 1912) is that the smaller one is the amoeboid dinofla-
gellate and that the larger one is a copepod egg to which the parasite has become
attached. It is thus a case of true parasitism, the dinoflagellate feeding upon
the contents of the egg and developing at the expense of its host.

With the increase in size of the parasite the nucleus begins to divide (fig.
K, 2), followed by cytoplasmic division (figs. K, 3, 4) of the entire body within
a eyst wall which has been formed around it. This process continues until
eight, sixteen or more small uninucleated bodies are formed (fig. K, 5). These
break out from the primary cyst, form secondary cysts corresponding to the
crescent-shaped ones of Gymnodinium lunula, and each daughter organism or
sporoblast, as Dogiel terms them, begins to divide (fig. K, 6). Division may
continue three times, the resulting minute bodies developing into a Gyminodi-
nium-like flagellate (fig. K, 8).

In Oodinium parasiticum a still further complexity has been introduced in
that the parasite enters the eggs and part of its development takes place therein.
The entire process is more obscure in this species than in Chytriodinium roseum.
The products of the final division of the parasite are small flagellates with the
typical flagella and girdle of the Dinoflagellata.

The striking similarity between the various stages of the life cycle of
Chytriodinium roseum and Gymnodinium lunula is probably due to the ecto-
parasitic mode of life of the former. Thus, while deriving its nourishment
from the body of the host, it is still exposed to the various influences of the
oceanic waters in about the same degree as Gymnodinium lunula. An appar-
ently much smaller gap is left in the life cycle of the parasitic form than in that
of the free-living one, since the small, amoeboid organism attaching itself to
the egg is similar in appearance to the small flagellate which has rounded up
and lost its flagella. It is possible, however, that an intervening stage may be
present here also.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 69

An endoparasitic mode of life places the heaviest burden upon the developing
organism, resulting in greater modifications of the body, usually in larger size
and in a more complicated type of development than is generally characteristic
of the ectoparasitic or non-parasitic forms. Whether these dinoflagellates are

facultative or obligatory parasites is a question, as their further development is
entirely unknown.

Bryary AND MuutipLe Fisston.—Binary fission in the Gymnodinioidae has
been noted by many investigators, but critical observation on the details of the
process has been lacking. This process has been followed out in the thecate

forms by Lauterborn (1895), Borgert (1910), and Jollos (1910), among others.
Tt differs from that found in the typical flagellate in that the plane of division

Fig. L. Binary fission in dinoflagellates. 1 and 2. Ventral views of dividing Ceratium hirundinella (O. F.
M.). After Lauterborn (1895, pl. 13, figs. 13, 14). X ? 1. Division of cytoplasm nearly completed, theca
parting along sutures (marked by heavy lines). 2. New thecal plates beginning to form. 3. Ventral view of
Ceratium in chain. After Kofoid (1909, pl. 1, fig. 1, two anterior schizonts and apical horn of the third).
X 405. 4. Daughter schizonts of Cochlodiniwm citron Kofoid and Swezy. After Kofoid and Swezy (1917,
fig. 8). XX 937.

is oblique and not longitudinal as in the larger group. In the thecate forms
this is undoubtedly an adaptation made necessary by the peculiar arrangement
of the plates, and enables the two moieties to separate at the sutures (figs. L,
1, 2) and not by the division of single plates, as would otherwise be necessary.

The plane of division of the simpler Gymnodinioidae appears to be more
nearly longitudinal, like that of the typical flagellates. In Prorocentrum the
bivalve theca parts along the longitudinal suture. However, in division in the
more specialized Gymnodiniidae, as in Cochlodinium, the position of the two
daughter cells strikingly resembles that in Ceratium (figs. L, 3, 4) at division
and leads to the conclusion that division in the unarmored forms is oblique as

70 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

it is in the thecate forms. The daughter cells in Ceratiuwm are attached to each
other at a definite point, the attachment area, which is the distal end of the
girdle of the anterior cell and the apex of the posterior cell (Kofoid, 1909c).
These points form the last bridge of direct protoplasmic continuity before final
separation of the daughter individuals. This relation of the two daughter cells
is identical in every respect with that which we find in Cochlodinium (fig. L, 4).
The more plastic body of these naked forms allows greater freedom of move-
ment and mutual adjustment than in the thecate forms. The relative dorso-
ventral orientation of the two cells is frequently reversed in their struggle for
freedom and separation by the rotation of one of the two schizonts and twisting
of the protoplasmic strand attaching them to each other.

h ) ,
s

a A aS ee
S
———— i
ST y

Fig. M. Dividing Gymnodinium heterostriatum nom. sp. nov. After Dogiel (1906, pl. 2, figs. 54, 55). 1.
Late anaphase of division of the nucleus. Note oblique position of nucleus. 2. Daughter schizonts nearly
parted. The final separation takes place at the region of the distal ends of the girdles, as in figures L, 3, 4.
x 500.

Further confirmation of oblique fission is found in Gymnodinium hetero-
striatum (fig. M) as portrayed by Dogiel (1906). Here the same relations of
structures are found as in Ceratium, with the final separation of the two
daughter cells occurring at the same place, namely, the anterior end of one and
the distal end of the girdle region of the other. As in Ceratium, too, the char-
acteristic features of the body become fully developed before final separation
of the two daughter individuals takes place.

There is some evidence that division in Oxyrrhis is oblique (Keysselitz,
1908) and that the daughter cells occupy a position similar to that of Cochlo-
dinium citron at the close of mitosis but prior to plasmotomy.

This condition is strikingly different from that obtaining in other groups
of the flagellates, where the separation begins at the anterior end and proceeds
to the opposite pole. This process in other flagellates never results in chain
formation of the daughter cells, such as is the rule in the dinoflagellates (fig. L).

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA (al

Some observations on collections made in the early morning lead to the
conclusion that fission takes place more frequently during the hours of night
or very early morning than at other periods of the day, indicating some relation
between nutrition and alternating darkness and light on the one hand and this
vital process on the other. Binary fission also seems to occur more frequently
during the life evcle than does the more complex process of multiple fission.
The former may occur in the unarmored forms in the motile state or after
encystment, the latter appearing to be the more common condition when fission
occurs.

S
Yl

Fig. N. Multiple fission in small Gyrodinium. 1. First division with girdles forming. 2. Second division
with beginning of third in upper zooid. 3. Sixteen individuals with fully completed girdles, but still closely
attached to each other. X 400.

Multiple fission has already been described as part of the life cycle of
Gymnodinium lunula (fig. 1), and consists of successive mitoses of the body,
resulting in the production of three to sixteen individuals within the same cyst.
Another type of multiple fission has occasionally been found in our material
which may represent another phase of the life cycle, or may be a specific modi-
fication of the process already described. This consists in the production of
few to many small individuals from one body within the ordinary oval, thin-
walled cyst (fig. N). Cysts of this type have been noted, which contained divid-
ing individuals of Gymnodinium, Gyrodinium, and Cochlodinium. These ap-
parently differ from the secondary cysts of Gymnodinium lunula in that they
are more delicate, resembling in every respect the ordinary cyst enclosing a
single individual of any of these species (as in fig. Q). The secondary cysts of
G. lunula, on the other hand, are tough and highly resistant, withstanding for
some time the action of preservatives of all kinds. It seems not improbable,
therefore, that a process of multiple fission may take place during the same
part of the life history as that in which binary fission occurs.

Another type of multiple fission was noted in a single individual only. This
was an elongated encysted form, apparently belonging to the genus Cochlo-
dinium, with the girdle still intact when first noted, though the suleus had be-
come obliterated (fig. O, 1). The nucleus of this individual presented a late

=~]
bo

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

telophase stage of division when first found. In a short time the girdle disap-
peared and the cytoplasm divided into two parts (fig. O, 2). In the course of
the next two hours a second (fig. 3) and a third (fig. 4) division took place,
resulting in the production of eight moieties, each with a single nucleus. Prob-
ably owing to adverse conditions under the microscope, the whole cyst began
to disintegrate at this stage, without further development. This would appear
to be a type of chain-formation not unlike that in faleate cysts of “‘Pyrocystis,”’
or of thecate forms such as Ceratium (Kofoid, 1909c) and Gonyaulax (Kofoid,

a

Fig. O. Multiple fission in Cochlodinium (?) elongatum sp. noy. 1. First division of nucleus. 2. First
division of cytoplasm. 3. Second division completed. 4. Third division. Further development of these was
not followed. X 500.

1912). It differs strikingly from that in Polykrikos, in which the duplication
of external organelles usually precedes nuclear division, whereas here this
division was unaccompanied by reduplication of cytoplasmic organelles.

ENcysTMENT.—It is evident that encystment plays an important part in
the life history of these minute organisms. Many forms, especially in the genus
Pouchetia, are usually found thus enclosed in the plankton, though generally
breaking out of their prison when placed under the stimulation of the high
degree of illumination necessary for the microscope. When first freed from
the cyst the flagellate becomes very active, its movements having a much greater
rapidity than has been observed in other individuals that have not recently
passed through this period of rest.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 73

Encystment in the dinoflagellates, at least in the marine forms, is probably
due to one of two causes. The first of these is the need for protection during
the non-motile stage of the period of multiple and binary fission. Binary fission
may occasionally take place in non-encysted forms, but is by far more frequently
seen in encysted ones. Multiple fission has never been observed in the non-
encvsted state in our material nor is it illustrated in the literature.

The second cause of encystment is correlated with a holozoic type of
nutrition. It is apparently induced by the ingestion of large food bodies, and
indicates a need for a quiescent period for its assimilation. There are several
reasons for this conclusion. One of these is the prevalence of food bodies
within encysted individuals. These may give indications of having been re-
cently ingested with few signs of digestive changes having taken place (pl. 8,
fig. 85), or they may represent partly digested bodies in what are evidently
older, larger cysts (pl. 8, fig. 87), or the final remains towards the end of the
period of digestion (pl. 8, fig. 89). When these encysted forms are observed
under the microscope a difference may usually be detected in their activities.
A recently encysted individual with a large food mass within its body is seldom
active and has never been observed to break out of the cyst. On the other
hand, those individuals which give indications of having neared the end of the
period of digestion within the cyst are active, rotating within the cyst and often,
while under observation, escaping from it altogether.

Another fact pointing towards the correlation of encystment with holozoic
nutrition is the relative infrequency of encystment in members of the group
having chromatophores, such as Amphidiniwm and the lower species of Gymao-
dinium, and its frequency among the higher genera of the group, such as Cochlo-
dinium and Pouchetia. Other causes leading to cyst formation are probably
operative on all groups alike, hence the greater frequency of its formation
among holozoic types would lead to the conclusion that a correlation exists
between these two factors named.

The cyst is first formed as a thin membrane secreted by the body wall and
closely investing it (fig. W,1). The flagella are apparently lost at the begin-
ning of the process and the membrane is closely adherent to the outlines of
both girdle and suleus. The flagella are probably absorbed, though no obser-
vations on this point can be presented except the occurrence of individuals with
short stout flagella. Very soon after the formation of the membrane the cyst
begins to enlarge as a result of the incoming fluids which fill the spaces between
the cyst wall and the body. With this distension the cyst gradually loses the
outlines of the body and becomes nearly symmetrical, either ellipsoidal or
spheroidal, varying in different species, but fairly constant in shape within the
species. The body also may lose its own characteristic outlines and furrows
and become rounded up (fig. P). The retention of the bodily features is the
condition more commonly found.

74 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

In some cases the cyst may reach relatively enormous proportions, and
secondary (pl. 8, fig. 89), or even tertiary (pl. 5, fig. 54; text fig. Q, 7) cysts may
be formed within the first one.

Some time before the organism breaks out of the cyst new flagella make
their appearance. These at first are very short (pl. 8, fig. 85), but reach their
normal length before the rupture of the cyst wall (pl. 8, fig. 87; pl. 9, fig. 101).
With the development of its motor organelles the minute organism usually be-
comes active, rotating in the cyst with nearly constant movement of the flagella.
In one instance Cochlodinium pirum (pl. 9, fig. 101) was held under observation
for several minutes before it escaped from the cyst, the size of which allowed
great freedom of motion. Its behavior was quite similar to the activities of a
small animal suddenly placed in a cage for the first time. It swam round and

]

Fig. P. 1. Encysted Pouchetia rubescens sp. nov. X 700. Food body present. Secondary cyst formed.
This became ruptured and gradually shrank away to one side of the enclosed organism. 2. Eneysted Nemato-
dinium partitum sp. nov. X 710.

round the cyst with the apex almost touching the wall but apparently without
exerting any pressure upon it, though the final result was the same as would
have occurred had actual pressure been exerted, that is, the wall suddenly burst
and the flagellate escaped from its prison.

Irregularities in the shape and size of the cyst may sometimes occur, though
not so frequently as might be expected in these delicate organisms. The unusual
evst enclosing Gyrodinium caudatum (pl. 9, fig. 102) may be due to some ab-
normality, but more likely it corresponds to the secondary cyst shown in text
figures I, 5, 6, 7, in which a single individual only has been developed (cf. pl. 2,
fig. 14).

As may be seen from figure Q, three kinds of cysts are formed. The large
globular cyst (fig. Q, 2) and the crescent-shaped ones are more resistant than the
others. The former is probably the resting stage of the organism. These are
frequent in preserved material and sometimes abundant.

The second type of cyst, which is also highly resistant, is the crescent-shaped
one. The wall of this is usually double-contoured and much thicker than the

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA

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oO

other types (figs. Q, 4,5). The shape of it varies considerably, and may pos-
sibly be influenced by the relative size of the enclosed dinoflagellate or even be
the homologue of a Pyrocystis stage. Thus in figure Q, 1, the outline is not
modified by the contained organism, while in figure Q, 6, considerable change
in shape results from the development of the relatively huge Gyrodinium
within it.

In the third type we find the digestive cyst, or the one commonly enclosing
the typical unarmored dinoflagellate when first observed under the microscope
(fig. Q, 5). This is thin-walled, hyaline, and varies in size from the closely
investing sheath that is first formed to one several times the length of the
enclosed organism. This cyst is always very delicate and easily ruptured, in
marked contrast to the other, stronger types. Successive cysts of this type may
be formed, one within the other (fig. Q, 7).

Fig. Q. Types of cysts in the Gymnodinioidae. 1. Gymnodinium sp. After Schutt (1895, pl. 25, fig. 80,)
2. Gymnodinium lunula Schiitt. After Dogiel (1906, pl. 1, fig. 2). 3. Cochlodiniwm pirum (Schutt). 4. Gymno-
dinium sp. 5. Gymnodinium lunula Sehiitt. 6. Gyrodinium falcatum (Schitt). After Schiitt (1895, pl. 25, fig.
81,). 7. Gyrodiniwm ovum sp. nov. Formation of three successive cysts. X 250.

Srex.—The question of sex and sexual phenomena in the dinoflagellates is one
about which, thus far, but little is definitely known. In only one member of the
Gymnodinioidae, Noctiluca scintillans, has conjugation been described (Ishi-
kawa, 1891). This process is stated to take place by the cytoplasmic fusion of
two isogamic, motile individuals, apparently of the normal type, whose nuclei
become apposed but remain distinct. Both the nuclei and the cytoplasm then
divide and the syngamic fusion takes place between the two nuclei in each of
the daughter cells thus produced. This is undoubtedly an incorrect interpre-
tation of the normal mitosis in which the large paradesmose so indents the
nucleus as to give the false appearance of two separated but apposed nuclei.

76 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Spore formation in Noctiluca is brought about by a rapid multiplication of
nuclei without corresponding cytoplasmic divisions. These nuclei retain their
position on one side of the spherical body. With the completion of the division
of the nuclei small buds of cytoplasm are formed projecting from one side of
the parent cytoplasm, each of which contains a single nucleus. These form
the flagellated ‘‘spores’’ which are possibly gametes, which remain attached to
the parent cell for some time before their liberation.

In the life cycle of Gymnodinium lunula an analogous stage to the spore
production of Noctiluca may be found in the Pyrocystis stage, when the body
divides into many crescent-shaped individuals, each of which passes through a
further process of division (fig. 1) producing small Gymnodinium-like flagel-
lates which seem to be equivalent to the swarm spores of Noctiluca, and may,
like them, be gametes. Whether this rapid multiplication is preceded by conju-
gation is undetermined.

In other groups of Protozoa where the life cycle has been followed out with
some degree of thoroughness it has been found that conjugation is usually fol-
lowed by rapid multiplication of the nuclei, resulting in the production of
numerous individuals. In Coccidium schubergi (Schaudinn, 1900) this process
is not unlike that followed in Gymnodinium lunula as far as the production of
the crescent-shaped spores. In the well-known life cycle of the malarial para-
site, Plasmodium vivax (Schaudinn, 1902), the same conditions are found.
Conjugation in Paramecium, among the ciliates, is followed by a comparable
phenomenon, though here the number of individuals produced is relatively few
(Doflein, 1911).

While no indisputable evidence can be offered on the subject of conjugation
in the dinoflagellates, yet these comparisons are suggestive. It is highly prob-
able that a process similar to that outlined for Noctiluca may also take place
in the Pyrocystis stage of other dinoflagellates.

A few instances may be found in the literature of so-called conjugation in
both the thecate and non-thecate dinoflagellates, but these have too much doubt
attached to them to be accepted without further verification. The first of these
was figured by Stein (1883, pl. 17, figs. 25-28) for Amphidinium lacustre.
These figures are identical with what have since been found to be division stages
in these forms, the two moieties still remaining attached to each other near the
region of the ends of the girdle (figs. L, M).

Among the thecate dinoflagellates Joseph (1878) has reported conjugation
for Peridinium stygiwm, and Zederbauer (1904) for Ceratium hirundinella. In
the latter case Zederbauer has figured a process similar to that found among
the conjugate algae. A conjugation tube is thrown out from the ventral suleal
region of each of two individuals. These tubes meet and fuse into a zygospore,
the protoplasmic contents of each cell flowing into it. These zygospores become
free and have the appearance of the usual thick-walled, encysted forms of the
dinoflagellates. Nothing comparable with this phenomenon has as yet been
discovered in the unarmored Dinoflagellata.

CHAPTER VII

EVOLUTIONARY DEVELOPMENT: RELATIONSHIPS, DERIVA-
TION, DEVELOPMENT WITHIN THE GROUP, STRUCTURAL
EVOLUTION, NUTRITION AND EVOLUTION,
RELATIONS TO THE METAZOA

The phylogeny of the Protozoa is a subject obscured by conditions inherent
in the organisms themselves, namely, the unstable and evanescent character of
their substance which, with many of the groups, requires but one minute or
less to disappear absolutely without leaving the faintest trace behind. This is
especially true of the Flagellata. While many of the flagellates have acquired
more resistant structures, such as the theca of the dinoflagellates, yet these
represent the terminations of the lines of evolution, and their preservation
throws no light on the earlier stages of their development or their interrelations.
The Flagellata also probably represent the most primitive class, with the pos-
sible exception of the lower bacteria, of which we have any adequate knowledge
today, and stand at the base of the phylogenetic trees of both the plant and
animal world. Thus the length of time during which they have been under-
going evolutionary development far surpasses that of any other group of living
organisms of the present day, and at the same time provides for a wider range
of differentiation and the more complete elimination of many connecting links.
This has resulted in the production of a group of organisms exhibiting, within
the compass of a single, minute cell, a wider range of differentiation and of
structural features than may be met with in any phylum or even groups of
phyla above the Protista.

Another factor tending to obscure our view of the evolution of these
organisms, but one which is daily giving way before the constant advance of
new discoveries in this field, is the lack of knowledge of the full life history of
the Protozoa. The older conception of a simplicity of life history for these
forms is gradually being replaced by a more adequate conception of what may
be the results on these plastic organisms of a long period of evolution in a
changing environment. In line with this comes a change also in the older idea
that these are the most simple forms of life. Indeed, the complexity which
we now find resident in a single cell, often containing neuromotor organelles
or an ocellus in addition to the usual complement of organelles for the purposes
of ingestion and digestion of food, secretion, excretion, and other life processes,
postulates a relatively higher stage of evolution than that reached by some of
the Metazoa. On the other hand, many of the flagellates especially are among
the simplest of known organisms both morphologically and in their life history,
as far at least as these are known, excluding of course the bacteria.

[77]

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MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

It is with this background, at once obscure, yet replete with the beginnings
of far-reaching lines of influence, that we must search for the early affinities
of the dinoflagellates. In lieu of a complete knowledge of the life histories of
these forms, which is an important desideratum in any scheme of classification,
the morphological features characteristic of the group must be used in tracing
out their relationships. Throughout the Protozoa generally the motor organ-
elles have been found to be the most satisfactory basic feature, correlated with
other cytological characters, for systems of classification, and it is in the
arrangement, number and insertion of these that relationships may be most
surely found.

In the dinoflagellates these relations of flagella and places of insertion with
the modifications connected therewith are typical and unique. The two main
divisions of the subclass Dinoflagellata are based upon the extent of the devel-
opment of these peculiar modifications connected with the motor organelles.
In the Adiniferidea the girdle and sulcus are entirely lacking or merely sug-
gested by the projecting fins and flagellar notch. In the Diniferidea they are
usually well developed at some stage of the life cycle. In both groups the
flagella have the typical dinoflagellate structure, consisting of a transverse,
ribbon-like flagellum and a longer, threadlike, longitudinal, trailing one. At
least it is possible so to orient the Adiniferidea as to harmonize them with this
interpretation.

ReLATIONSHIPS.—The relationships of the Adiniferidea, represented by the
genera Prorocentrum, Exuviaella, and Cenchridium, have long been a problem
concerning which protozoologists have held widely divergent views. The reason
for this lack of agreement appears to be the fact that the Adiniferidea, though
they are relatively simple in structure, yet have a bivalve theca. The thecate
forms (Prorocentridae and Peridiniidae) are probably derivatives of the athe-
cate ones (Protodiniferidae and Gymnodinioidae), the primitive forms of the
latter being more like the other and simpler types of Flagellata.

This possession by the Adiniferidea of an exoskeleton or theca of an entirely
different type from that of the Diniferidea, which skeleton indicates an advance
in evolution on the one hand, while on the other a relatively simple type of
structure and absence of the girdle, has led protistologists in opposite directions
in estimating the relationships of the Adiniferidea. Those who have felt the
importance of the skeleton in the dinoflagellates as a whole have regarded the
Adiniferidea as primitive representatives and have placed them at the base of
the phylogenetic tree, as did Bergh (1881b) and Biitschli (1885a), who first
attempted the systematic organization of the group.

When this primitive role is assigned to the Adiniferidea a new difficulty
arises with regard to the relationships of the Gymnodinioidae, which are devoid
of skeleton and contain some of the simplest types of dinoflagellates, as well
as some of the most diversified and complex, possessing, for example, eyespots
with lens and pigment body, and even nematocysts. Both Bergh (1881b) and

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 79

Biuitschli (1885a) solved this difficulty by putting Gymnodinium and allied
genera at the top instead of the base of their phylogenetic tree, thus giving rise
to the conception that the athecate condition is secondarily derived and not a
primitive one.

With the increase in our knowledge of the structure, abundance and
speciation of these naked dinoflagellates there has come a reversal of opinion
in respect to their being derivative instead of primitive types. This is shown
in the system proposed by Schutt (1896) in his treatment of the Dinoflagellata
(Peridiniales) in Engler and Prantl’s Pflanzenfamilien. He placed the
Gymnodiniaceae as the first or most primitive family, the Prorocentraceae next
and the Peridiniaceae as the terminal family. This linear arrangement brings
the Prorocentraceae between the Gymnodiniaceae and the Peridiniaceae and
thus parts near allies with an entirely divergent family intervening. Klebs
(1912) held to a similar view, placing the Gymnodiniaceae in the primitive
position and deriving the Prorocentraceae from them by way of Amphidinium.
Poche (1913) grasps the other horn of the dilemma and places the Prorocen-
trinea in the primitive position with the Peridiniinea next, within which he
brings the two related tribes, Gymnodinioidae and Peridinioidae in the sequence
of their evident relations. This arrangement places the thecate Prorocentrinea,
however, as the most primitive group. Doflein (1911) gives the primitive
position to the same group in his Adinida with the Dinifera containing Gymno-
dinidae, Peridinidae and Dinophysidae. Cavers (1913), and later West (1916),
have suggested still another solution to these difficulties by giving to the Dino-
flagellata a diphyletic origin, with the Prorocentraceae having a separate origin
from the Gymnodiniaceae.

The dilemma which has thus arisen is plainly one resulting from the fact
that we are here dealing with the divergent and largely terminal branches of
an evolving group, of the more primitive forms of which we have had too little
knowledge to elaborate any satisfactory systematic arrangement which ade-
quately represents the true relationships of these main divisions of the
Dinoflagellata.

The search for more primitive representatives of the Dinoflagellata which
will show connections with other divisions of the Flagellata and, at the same
time, afford a common starting point for the Prorocentridae and the Peridi-
nioidae is well illustrated in the contributions of Klebs (1912), Cavers (1913),
and West (1916). Their search leads them among the Chrysomonadina and
Cryptomonadina, which include among others biflagellate, asymmetrical flagel-
lates with yellow chromatophores. Klebs adds a new genus, Haplodinium, with
characteristic dinoflagellate nucleus, two characteristically differentiated fla-
gella, and a continuous, cellulose-like membrane covering the body without sub-
divisions or pores. He includes this in the Prorocentraceae and modifies the
definition of the family to provide for the inclusion of this new, brackish-water
genus.

80 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Cavers (1913) gives an extensive review of the interrelations of the flagel-
lates and lower Algae with a predominant utilization of the fresh-water forms,
which are perhaps better known than marine ones. In his phylogenetic group-
ing he derives the branches leading to the Gymnodiniaceae and the Prorocen-
traceae from two different groups of the cryptomonads, Protochrysis and
Wysotzkia, with a questioned derivation of the diatoms from the Prorocen-
traceae.

No connecting link between these two groups of dinoflagellates has hereto-
fore been found which would present a reasonable basis for claiming a closer
relationship between them. This gap we feel has been bridged by the genus
Protodinifer, described in this paper, taken together with the genus Haplodi-
nium, recently described by Klebs (1912). The former lacks the theca of
Prerocentrum, but has a similar orientation, with its tentacle extending from
the anterior end as the spine does on the theca of Prorocentrum.

Thus Protodinifer has the appearance of a Prorocentrum which has escaped
from its theea. A more profound difference separates them, however, in that
the former shows the beginnings of a girdle which is poorly developed and
apparently a temporary depression only, 0.5 transdiameter or less in length,
with a feebly developed suleus. Haplodinium also lacks a theca of discrete
plates and tentacle as well as the girdle and sulcus of Protodinifer, but its
orientation and arrangement of flagella are similar to those of Prorocentrum
(ig. IR, 7).

With these two genera as a starting point two possible lines of development
are open. The first of these starts near Protodinifer and leads to the Gymnodi-
nioidae by way of Oxyrrhis (figs. R, 2+). The latter genus still shows a poorly
developed but posteriorly located girdle. The second line of development goes
from Protodinifer or other non-thecate forms to Haplodinium (fig. R, 5), with
its membranaceous, cellulose-like covering of the body, and to the thecate forms
Exuviaella (fig. R, 6) and Prorocentrum (fig. R, 7). Of these genera the
athecate Protodinifer is obviously to be regarded as the more primitive.

The development of the thecate from the athecate forms is a natural process
of evolution which is repeated for each individual in the growth of a new theca
or part of a theca at every recurring division.

In thus establishing the relationships of the Adiniferidea and the Dino-
feridea a monophyletic origin for the Dinoflagellata becomes a logical conelu-
sion. This, as has been suggested by Bergh (1881b) and more fully by Cavers
(1913), would probably be found in the cryptomonads, though not as the latter
has postulated, as two distinct series of independent origin. Of the two genera
which Cavers has suggested as the starting point for his two series leading up
to the two separate groups, Protochrysis to the Gymnodiniaceae and Wysotzkia
to the Prorocentraceae, Wysotzkia (fig. R, 1) seems more nearly related to the
Adiniferidea than probably any other genera of the cryptomonads. With a
form nearly allied to these as a starting point the progressive evolution of the

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 81

group as a whole may be traced out with the widest gaps near the beginning of
the series (figs. R, 8).

The fact that both Wysotzkia and Protochrysis are fresh-water forms
renders it highly improbable that these particular genera are to be considered
immediately in the direct line of evolution. They can be only persistent morph-
ological types, significant in structure of the common ancestral marine types
from which both they and the marine genera have been derived.

Fig. R. Derivation of the dinoflagellates. 1. Wysotzkia biciliata (Wys.) Lemm. After Cavers (1913,
fig. 7;). 2. Protodinifer tentaculatum sp. nov. 3. Oxyrrhis marina Dujardin. After Senn (1911, pl. 30, fig. 9).
4. Hemidinium nasutum Stein. After Stein (1883, pl. 2, fig. 25). 5. Haplodiniwm antjoliense Klebs. After
Klebs (1912, fig. 1 A). 6. Bxuviaella marina Cienkowski. After Schiitt (1895, pl. 1, fig. 1.). 7. Prorocentrum
micans Ehrbg.

So far as present knowledge goes the Dinoflagellata .of today probably
represent the terminal twigs of the phylogenetic branching (fig. S) of some
such simple flagellate, and the genera cited are not intermediate stages leading
on to more highly developed forms.

The attempt to find ciliate affinities for the genus Polykrikos grew out of a
misinterpretation of the structural relations of that remarkable organism.
Biitschli (1885@) and later Bergh (1881b), noting the presence of more than
one nucleus, with slight variations in size among them, correlated them with
the nuclei of the Ciliata as macronuclei and micronuclei. Cavers (1913) further
states that ‘‘whether Polykrikos forms a link between the Peridiniales and the
ciliate Infusoria is, of course, an open question in the absence of further transi-
tional types.’ Our own work on this genus confirms that published earlier by

82 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Kofoid (1907), namely, that Polykrikos is a simple colonial gvmnodinium-like
organism with the zooids remaining united in a permanent somatella after
binary fission, and the number of nuclei equal to the number of zooids, or to
half that number. Temporary colonial organization of the linear or chain type
is often found in the dinoflagellates and permanent colonies and less or more
permanent somatellas are common in other groups of the Protozoa, which have
no suggestions of ciliate affinities attached to them. Variation in size of the
nuclei, resulting from successive mitoses, is also a common phenomenon and is
no more striking in Polykrikos than in other protozoan forms.

Cavers further suggests the possibility of the genus Hrythropsis affording
a transition stage between Polykrikos and the Ciliata. A comparison of the
structures of these two widely different organisms (figs. F, RR) will at once
demonstrate the futility and morphological folly of looking for the origin of
the Ciliata near these highly specialized flagellates, the structure of which differs
profoundly from that of present day ciliates. The types of specializations
found in the Dinoflagellata, represented on one line by the thecate forms, on
another by Erythropsis, and on still another by the extremes of torsion in
Cochlodinium, are not intermediate types which lead on to other groups of
Protozoa, but are rather the culmination of their particular lines of development.

Derivation.—The derivation of the Dinoflagellata from some primitive
flagellate allied rather closely to existing Cryptomonadina, with two anterior
flagella and xanthophyll chromatophores, seems the most probable of all pos-
sible lines of origin. The discussions of Pascher (1911), Klebs (1912), and
West (1916) serve to establish this, although their utilization of fresh-water
genera such as Wysotzkia and Protochrysis as primitive connecting links seems
less tenable. When the marine cryptomonads are better known it may be that
as good or better morphological links will be discovered between cryptomonads
and dinoflagellates.

The differentiation of one anterior flagellum to form the spirally wound,
ribbon-like collar of the craspedomonads, to form the trailing flagellum in the
Bodonidae, and to develop into the attached, posteriorly directed, undulating
membrane of Trichomonas, is suggestive of a widespread and deep-seated
tendency for the two or several flagella of primitive types to become differen-
tiated. This differentiation of the two flagella into a trailing thread on the
one hand and a closely sinuous ribbon on the other is the basis of dinoflagellate
evolution, and establishes the fundamental connections between the Adiniferidea
and the Diniferidea. It is to be expected that the primitive cryptomonad with
dinoflagellate affinities will show this differentiation in structure or position,
or both, of these flagella. These conditions are fulfilled to some extent by
Haplodinium and Protochrysis, the first allied to the Adiniferidea and the
second to the Diniferidea, but both are fresh-water forms. We may therefore
regard these genera as at least allied closely to the stock of cryptomonads from
which the primitive dinoflagellates took their origin, but it is to be hoped that
still closer allies will be found among marine flagellates.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA

(o2)
ie)

It is obvious that the Adiniferidea and the Diniferidea must have been quite
distinct, except in the matter of the two types of flagella, even at a very early
stage in the evolution of the dinoflagellates, and that the porulate, bivalved
skeleon of Prorocentrum and its allies evolved independently from that of the
thecate forms of the Diniferidea with epitheca and hypotheca. In the Adini-
feridea the original functional polarity of the cryptomonad is preserved, while
in Protochrysis, Oxyrrhis, and the Diniferidea generally, the flagellar pore is
no longer terminal but midventral. It therefore seems necessary to regard the
Adiniferidea as a basal offshoot from the primitive dinoflagellate arising from
eryptomonad stock, which offshoot has paralleled the Diniferidea in the acquire-
ment of a porulate theca. It is quite possible that the plane of division between
the two plates or Prorocentrum, between the two sides of the theca of the Dino-
physidae, and the oblique zigzag suture parting the two moieties of the theca
at mitosis in some of the Peridinidae, are all homologous planes, although the
actual evolution of the theca appears to have followed the separation of the
groups and to have been an independent acquisition in each. The varying
modes of separation of the theca into two parts are differentiations of a funda-
mental, bipartite tendency which we see expressed in the two valves of Phacotus
lenticularis, in the two chromatophores of many chrysomonads, and in the two
parts of the theca of the dinoflagellates and of the diatoms. The obliquity of
the plane of fission in the Dinoflagellata may well be a consequence of the
ventral position of the blepharoplast and flagellar pores.

Assuming this early separation of the Adiniferidea and Diniferidea prior
to the acquisition of the theca in either, we may present our conception of the
evolution and relationships of the dinoflagellates in the following diagram
(fig. S).

Among existing Cryptomonadina the genus Wysotzkia is near the type from
which by differentiation of the two flagella such a genus as Haplodinium
might readily be derived, while Protochrysis with its midventral flagella is a
natural link to Oxyrrhis with the initial stages of the girdle, the fundamental
characteristic of the Diniferidea.

The newly discovered genus Protodinifer with the anteriorly located flagella,
which are differentiated into one posteriorly trailing and the other encircling
the anterior end, is a connecting link bridging the gap between the Adiniferidea
and the Diniferidea. The flagella are still in or near the primitive position as
in the Adiniferidea, but in their differentiation in direction and functon they
are of the type in the Diniferidea, although the transverse flagellum has not the
broad, ribbon-like form of that group and does not lie in a completed permanent
girdle. Since Protodinifer has an active functional tentacle-like projection
arising near the flagella it cannot be regarded as a generalized or primitive
form in this particular, although in all others it may be so designated. It is
strongly indicative of the common origin of the two main subdivisions of the
Dinoflagellata and might be placed in either with almost equal propriety. How-
ever, in view of the location of the flagellar pore near the anterior end of the

84 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

body, and the absence of a completed permanent girdle, we have placed it as
the primitive non-thecate representative of the Diniferidea and regard the
Adiniferidea as an offshoot of this primitive stock.

Erythropsis
Nematopsis

Pouchetia
Ceratium

Proterythropsis
Protopsis

Ceratocorys

/ Gonyaulax

6 Peridinium
pee Ty

7m ee

Cochlodinium

Noctiluca

wt
oe ait
0
3 mt Se
8 GY pte
Dinophysidae Vp, %,- al Blastodintidae
Loy. AS)
es, a Hemidinium
2 3
i—J
_— poet if
Prorocentrum cee ia
Exuviaella i
= = Oxyrrhis
Y =
qx ty}
Haplodinium &, a
P Ry =
os =
Sf 1S)
Wysotzkia — 4 7 Photochrysis

CRYPTOMONADINA

Fig. S. Diagram of phylogenetic derivation and relationships of the Dinoflagellata.

The plastic or generalized nature of Protodinifer is indicated also by the
ease with which it progresses in either direction, though predominantly with
flagellar end leading, and yet again by the fact that the transverse flagellum
may be thrown about the body loosely and in either direction, though predomi-
nantly in the normal position of the Diniferidea.

With Protodinifer and Oxyrrhis recognized as primitive members of the
Dinoflagellata and of the Diniferidea, it is a natural conclusion to regard the
Gymnodinioidae as the basal group of the Diniferidea from which its thecate
representatives have sprung, while the process of evolution has continued un-
abated within its non-thecate forms with resulting high specialization in
Pouchetia, Cochlodinium, and Erythropsis; with colonial organization appear-
ing in Polykrikos; with simplification in structure in the dinoflagellate phase,

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 85

but with complication in life history resulting from the parasitic habit, in the
Blastodiniidae.

We have withdrawn Noctiluca from the Cystoflagellidae and placed it as
one of the Gymnodinioidae, diverging at a low level in the specialization of the
group. The ‘‘Pyrocvstaceae’’ of Murray, Apstein, and West disappear wholly
as merely a phase of the life history of other, and in some cases as yet unknown,
dinoflagellates.

DEVELOPMENT WITHIN THE GrouP.—Within the dinoflagellate group as a
whole several distinct lines of morphological development with resulting speci-
ation may be traced. One of these lines follows the differentiation of the struc-
tures correlated with the motor organelles. These structures, the girdle and
suleus, form the most characteristic features of the dinoflagellates and are the
ones having the greatest value for diagnostic purposes.

The first beginnings of the girdle and sulcus in the genus Protodinifer and
their continued development in Oxyrrhis (figs. R, 2,3) have already been noted.
It is, however, within the family Gymnodiniidae that they reach their typical
form and also their greatest development in the Dinoflagellata, together with
the torsion of the body which is closely dependent thereon. In this group the
line of increasing specialization presents an orthogenetic series notable for its
well defined, progressive differentiation that links the members of the family
closely together. Hemidinium, while probably not the most primitive genus in
the family, yet stands near the base of development of these two critical features
of the Dinoflagellata. In this genus the girdle is short, its length being 0.5 turn
around the body, with the sulcus extending from the girdle to the antapex (fig.
C, 1), and with both flagella arising near or at the same midventral point. ‘The
development of these structures in Hemidiniwm marks a distinct advance be-
yond that attained by the genus Oryrrhis (fig. R, 3) in that the girdle and
sulcus have definitely marked borders, sharply delimiting them.

In the genus Amphidinium (fig. C, 2, 3) the girdle has lengthened to a
complete turn around the body, its position being anterior, instead of median,
as in Hemidinium, thus increasing the length of the sulcus and hypocone and
decreasing that of the epicone. In many of the species of this genus, like
Hemidinium, Oxyrrhis, and earlier forms, the flagella arise near together at
the proximal end of the girdle (fig. R). In a few species of Amphidinium,
however, the flagella have become more or less widely separated (figs. U, 1, 4, 6).
In the further development of these forms this becomes the usual condition,
as in Gyrodinium (figs. CC, DD) and Cochlodinium (figs. GG, HH). The
sulcus also may increase in length, extending from the apex to the antapex.

In Gymnodinium we find a type of girdle similar to that of Amphidinium,
but in this genus its location has become submedian, or at least has moved
considerably posterior to its position in Amphidinium, with a resulting increase
in the relative size of the epicone (figs. C, 4,5). G. doma (fig. C, 4) represents
a stage of this posterior migration which is only slightly removed from the
condition found in Amphidinium scissum (fig. C, 3). In Gymnodinium the

oe)
for)

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

girdle may form a closed circle (figs. X, 1, 2, 8, 17) or its distal end may become
displaced posteriorly to any distance less than 0.2 of the total length of the
body (fig. Y). The extreme of this condition is found in G. rubrum (fig. C, 5),
which closely approaches the next genus, Cochlodinium (fig. C, 6), in its type
of girdle arrangement.

The advance from the genus Gymnodinium to Gyrodinium is but slight in
the species at the adjacent extremes of both genera (figs. C, 5, 6). Within the
latter genus, however, the progress made in increasing development of the girdle
and suleus is considerable. Here the ends of the girdle are displaced about
0.2 of the total length of the body at the lower end of the scale (fig. C, 6). From
this point upward an increasing progressive displacement of the ends of the
girdle is found (fig. CC) which reaches its greatest extent in G. cornutum (fig.
C, 7). where it is slightly more than 0.5 of the total length of the body. The
girdle also increases in length so that more than one complete turn of the body
is made (fig. C,7). This results in a torsion of the body and also of the sulcus
which is carried about with it. In this genus the torsion never becomes as
great as 1.5 turns of the body (fig. CC).

In the torsion of the body the next genus, Cochlodinium, exhibits the maxi-
mum of specialization found in the Gymnodinioidae. The amount of torsion
varies from 1.5 in those species near the border line separating this genus from
Gyrodinium (fig. C, 8) to four complete turns of the body in the most highly
differentiated species (fig. C, 10). Between these two extremes all gradations
in the amount of torsion may be found (figs. GG, HH). Torsion of the suleus
also reaches its maximum in this genus, always having approximately one less
turn than that of the girdle because of their morphological relations.

The lines of separation of Amphidinium, Gymnodinium, Gyrodinium, and
Cochlodinium must of necessity be somewhat arbitrary, since the great increase
in the number of species results in an increase also in the number of inter-
mediate forms linking together the extremes of each genus. The gap between
Hemidinium and the other members of the family is much harder to bridge.
It is a genus of little known, fresh-water forms of which two species only have
been described.

The remaining genus of the family, Polykrikos, is a colonial Gymnodinium
which has secondarily developed nematocysts, and may be considered an off-
shoot of that genus. Temporary colonial chain formation is frequently seen in
Gymnodinium and Cochlodinium as well as in the theecate forms, Ceratium,
Peridinium, and Gonyaulax. The colonial organization of Polykrikos, how-
ever. seems to have acquired permanency. It shares with the genus Nemato-
dinium the distinction of being the only genera in the Dinoflagellata possessing
nematoeysts.

The five genera of the family Pouchetiidae present another clear instance
of progressive orthogenetic differentiation culminating in the most complex
types of the Gymnodinioidae, even of the Dinoflagellata, with respect to the

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 87

locomotion and sense organs, and with respect to the ocellus, of the Protozoa
asa whole. Protopsis is clearly a generalized, primitive genus, with girdle and
suleus still at the level of Gymnodinium and Gyrodinium, the ocellus scarcely
integrated and the coloration not advanced beyond the ochraceous stage preva-
lent in simpler Gymnodinioidae. It is thus evident that this genus is most
closely related to the generalized species of Gymnodinium and Gyrodinium,
showing no advance beyond these forms, save in the development of its ocellus,
The presence of pigment in the more generalized species of Gyrodinium prob-
ably is related to the development of the pigmented portion of the ocellus or
melanosome in Pouchetia, Protopsis, and Erythropsis.

' Fig. T. Development of prod of Erythropsis. 1. Cochlodinium cavatum sp. nov. 2. Pouchetia maculata
sp. nov. 3. Proterythropsis crassicaudata sp. nov. 4. Erythropsis extrudens sp. nov. X 500.

In the genus Nematodinium (fig. NN) we have an offshoot of a group of
divergent species representing a considerable degree of specialization of the
girdle and sulcus. These are separated from the remainder of the family by
the presence of nematocysts. The only other genus of dinoflagellates with these
unique organs is the genus Polykrikos. No apparent close relation exists be-
tween the two groups, however. This would suggest an independent origin for
these structures in Nematodinium, unless, as may probably be the case, the
connecting links between the two genera have disappeared.

In the genus Pouchetia (figs. OO, PP) we find the extreme development of
the suleus in length, torsion, extent of apical and antapical loops, and its con-
striction of the body. Here the girdle is usually shorter and less conspicuous
than the suleus, unlike its condition in the lower genera where the sulcus is
still primitive, whereas the girdle may become more highly complicated as in
Cochlodinium.

The close relationship of the family Gymnodiniidae and the family Pouche-
tiidae is clearly indicated in certain points in their structure. One line of
specialization linking together these two groups is found in the increasing
differentiation of the ventrosuleal region, culminating in the production of the
prod of Erythropsis. The beginnings of this line may be looked for in the
genus Cochlodinium. Here an increasing degree of mobility of the plastic
suleal area near the posterior end of the body is present in C. convolutum (fig.

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

wm
lo 2)

HH. 5), C. helix (fig. HH, 8), and reaches its greatest development in the genus
in C. cavatum (fig. T, 1). In Pouchetia this same mobility occurs, as seen in
P. maculata (fig. T, 2). A further development is found in Proterythropsis
crassicaudata (fig. T, 3). This line of specialization reaches its climax in the
genus Erythropsis (fig. T, +), with its highly developed prod, provided with
protractile and retractile fibrillae on the prod, which has developed from the
mobile region of the sulcus.

Another form of specialization is found in the development of a tentacle.
Jn the genus Protodinifer this is anteriorly located (fig. R, 2). In Pavillardia
(fig. JJ) it is posteriorly placed, is more mobile, and may reach a greater
length than in Protodinifer. In Noctiluca the greatly modified form of the
body, which here becomes a huge sphere, makes it difficult to give to the tentacle
an exact location that will link it with that in the other genera. It is closely
connected with the remains of a furrow and with the flagellum, hence it prob-
ably has its origin in a part corresponding to the sulcal area of other dinofla-
gellates. There is little evidence if any that these three types of tentacles have
any derivative connection other than origin in common territory.

Another line of development that closely links the two groups may be
found in the melanosome of the highly specialized ocellus of Pouchetia and
Erythropsis.. In the Gymnodiniidae, where the lens formation has not yet taken
place, the pigment is scattered through the body, often massing at the apices or
near the girdle. The pigment occurring in the family Pouchetiidae has become
massed around the lens in the typical melanosome near the girdle. There is
no ocellus elsewhere in the Dinoflagellata, or indeed in the Protozoa as a whole,
comparable with this integrated organ composed of a laminated, oriented lens
embedded in a melanosome enclosing a highly pigmented, presumably sensory
core. The stigma of fresh-water dinoflagellates is a single mass, ellipsoidal, or
broadly horseshoe-shaped, lying in or near the sulcus, but not consistently at
its left. It does not appear to be similar in structure to or homologous with
the ocellus of the Pouchetiidae, but the two are rather independent specializa-
tions of pigment-producing plasma.

The production of pigments is widespread among the more highly differ-
entiated species of the related genera Cochlodinium, Gyrodinium, and even in
the more generalized species of Gymnodinium. Melanin, however, is produced
in these lower genera only in two species, Cochlodinium atromaculatum (pl. 7,
fig. 71) and Gyrodinium spumantia (pl. 7, fig. 72). The occurrence of such
pigments and of refractive spherules within the evtoplasm of these lower genera
has doubtless been the starting point from which the evolution of the ocellate
species of this family has proceeded. Various stages of the integration of the
ocellus are found within the group.

The evolution of the ocellus within the Pouchetiidae presents several ortho-
genetic series proceeding along different lines independently of one another but
parallel in the different genera, in each case starting with the diffuse, scattered,

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 89

scarcely organized, variously directed, posteriorly located, and functionally in-
efficient form, as found in Protopsis (fig. LL), and culminating in the con-
centrated or more highly integrated, anteriorly directed, and functionally
efficient form of the organ. This is best seen in Pouchetia and Erythropsis,
where the known species are sufficiently numerous to afford a range of types.

In most of the species of Pouchetia the ocellus presents a high degree of
integration (figs. OO, PP). It is in the genus Erythropsis, however, that this
peculiar organelle reaches its highest tvpe of development as well as its greatest
size. as in EF. cornuta and EF. pavillardi (figs. SS, 1, 3). Evidence of a lesser
degree of integration is also found in this genus, as in E. labrum (fig. SS, 6).

SrrvucturaL Evontution.—The influence of the peculiar types of flagella
characteristic of the dinoflagellates and their peculiar position has undoubtedly
played an important part in producing the other structural modifications of
that group. From this standpoint the most fundamental feature is the ribbon-
like transverse flagellum. In the lower forms, such as Protodinifer, Haplo-
dinium. and Prorocentrum (figs. R, 5,7), both flagella arise at the extremity of
the body, and no profound structural modifications thereof result. With the
migration of the flagella from this point, however, changes begin to take place.
These consist of the formation of a groove or girdle (fig. B, gir.) around the
body for the lodgment of the transverse flagellum, and another furrow which
we call the suleus (fig. B, suc.) ina longitudinal direction on the ventral surface
which contains the longitudinal flagellum. The sulcus also extends anteriorly
and sometimes posteriorly beyond the area of its actual functional relations to
the flagellum.

The beginning of this process may be seen in Protodinifer with its poorly
developed, evanescent girdle (fig. R, 2). In Oxyrrhis it has extended com-
pletely around the body, but is still poorly developed, with ill-defined posterior
border (fig. R, 3). It reaches its highest development in the next group, the
Gymnodiniidae.

The formation of both furrows is due to the direct influence of the activity
of the flagella on the surface of the body. In Protodinifer the transverse
flagellum has a greater length than the circumference of the body and lies in-
differently in several positions. Its activity would be felt on all parts of the
circle, but more strongly near its origin, where we find accordingly the begin-
nings of the girdle. The greater part of the flagellum in this species is not held
close to the body, as is the case in the higher members of the group. In the
Gymnodiniidae the flagella are frequently short, not more than 0.5 cireumfer-
ence in length, especially in moribund individuals. Many other species, how-
ever, especially in Cochlodinium (fig. HH, 3) and Pouchetia (figs. 00,5; PP, 3),
have the transverse flagellum equal in length to the girdle, and this is probably
the normal condition.

The action of a broad, ribbon-like flagellum in constant motion with short,
transverse waves, passing through its entire length and held close to the body,
would have a profound influence in hollowing out for itself in the plastic body

90 MEMOIRS OF TH# UNIVERSITY OF CALIFORNIA

wall a furrow slightly wider than the amplitude of its vibrations. <A similar
origin for the longitudinal furrow or sulcus seems evident. In the simpler
forms both flagella arise from or near the same point (figs. X, 2, 14), hence we
find the sulcus extending from the girdle to the posterior end of the body, with
a gradual widening posteriorly to accommodate the movements of the flagellum.
With the deepening of this furrow a secondary modification is introduced, in
that the depression extends anteriorly above the girdle. In Gymnodinium
bifurcatum (fig. AA, 3), where the sulcus bifurcates the hypocone, the flagellum
is found to swing freely through the cleft thus made, often projecting from the
body from the dorsal side, instead of from the usual ventral position.

With the continued increase in the length of the transverse flagellum the
length of the girdle has kept pace with it. This, combined with the rotation of
the body, has resulted in a spiral course for the girdle with its distal end dis-
placed posteriorly, and gradually pushed farther and farther around the body.
The culmination of this lengthening is seen in Cochlodinium, where, in its most
specialized species, the girdle may make no less than four turns around the body.

The continued lengthening of the sulcus in these highly specialized forms
was not necessary to accommodate the longitudinal flagellum, which has retained
a position near or slightly posterior to the distal end of the girdle. The conse-
quence is that this flagellum is not involved in the resulting torsion of the body
in the intercingular region. In the meantime, with the development of holozoic
nutrition, the intercingular part of the sulcus had become the area for the
ingestion of food, and hence was necessary in the economy of the organism.
Its development, therefore, kept pace with that of related structures. In the
Peridinioidae elaborate fins, or lists, further outline both girdle and sulcus, and
guide the currents of water which course through them.

Tn the arenaciphilous group of dinoflagellates certain features are possessed
in common by most of the species, which probably owe their development to
the influence of their habitat. These forms range in length from 17 to 56, a
size which is considerably below the general average for the Gymnodinioidae
asa whole. This small size is evidently an adaptation to the habitat in which
the organisms live, enabling them to move more readily through the interstices
between the grains of sand and to escape, to some extent, its crushing effects
during its not inconsiderable movements. Another adaptation for the same
purpose is the strong dorsoventral flattening of the body, giving to it a thin
disk shape that is very rarely met with in the characteristically pelagic or
neritic forms. Species showing these medifications are found in three arena-
ciphilous genera, as in Amphidinium steini and A. scissum (figs. C, 2, 3),
Gymnodinium agile (fig. Y, 9), and Gyrodinium viridescens (fig. DD, 11). The
deep suleal groove with its overhanging flaps is utilized as a holdfast, an
adaptation to the conditions of life in shifting sand.

Another significant fact is that most of the species found in this habitat
are green in color. This is perhaps correlated with the fact that the beach at

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 91

La Jolla, as elsewhere, is fully exposed to the light and that the illumination
in this latitude (33°) is fairly direct during midsummer.

In the pelagic and neritic forms a wider range of variation in form is found,
combined with a generally larger size and more brilliant coloration. The fresh-
and brackish-water species are closely akin to the sand beach forms in their
general characteristics. They usually possess green or yellow ochre chromato-
phores, and are small in size, with a strong tendency towards a dorsoventral
flattening of the body. These tendencies are shown in Amphidinium lacustre
(fig. U, 15), Gymnodinium tenwissimum (fig. AA, 7), and Gyrodinium hyalinum
(fig. CC, 15).

NUTRITION AND Evotution.—West (1916) has suggested that saprophytic
dinoflagellates are probably mostly degenerate forms. There is no evidence
for this, however. On the contrary, it seems quite probable that a saprophytic
mode of nutrition is a natural one for many of the Flagellata, and, furthermore,
that it is the intermediate stage between the holophytic and holozoic types.
There are several reasons which point to this conclusion. One of these is found
in the intimate correlation existing between the method of food-getting and
the structure of the body.

There is in many, if not most, of the holophytiec flagellates a close correlation
between the presence of chromatophores and a thickened cuticle, or periplast,
surrounding the body. This is shown most strikingly in Huglena. With the
disappearance of chromatophores the periplast becomes thinner, often scarcely
detectable as such, and remains so until a definite oral region has become evolved
with accessory structures for the ingestion of food. When this stage in the
evolution of the protozoan has been reached a corresponding amount of ecto-
plasmic differentiation takes place, most noticeable in the ciliates with their
more complicated structures. A secondary modification is found in the
Rhizopoda in the development of pseudopodia, correlated with a thin periplast
for the ingestion of food. Very many of the small flagellates which live in
stagnant water rich in decaying plankton show an absence both of chromato-
phores and distinct food bodies in the cytoplasm, as well as an absence of a
definitely marked cuticle. So far as evidence goes in these forms nutrition is
evidently of the saprophytic type.

In the typical vegetable organism the raw materials enter the protoplast
in a state of solution and are there elaborated into assimilable form by means
of special organelles and enzymes. This is a more primitive type of feeding
than the holozoic method, by which solid food substances are ingested. The
transition between the two methods must have been a stage in which the already
elaborated material entered the protoplast by osmosis in a state of solution and
was ready for assimilation by the cell without the aid of special organelles or
enzymes. A thin periplast covering the body is a very necessary factor in
feeding by osmosis, and we find this cell covering in its most ideal state among
these flagellates. A further advance in evolution is required before the organism

Ne}
bo

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

is ready to take in another living body and break down an organization similar,
and chemically equal, to its own to render it available for its own use.

The transition stage between these two groups must be looked for in the
relatively large group of flagellates not far removed from the base of the
phylogenetic tree. The increasing evidence points to the fact that both types
of nutrition, as well as the intermediate saprophytic type, are found in forms
otherwise closely related, and even in the same individual either at the same
time or under the stimulus of different environmental conditions (Zumstein,
1899).

This advance in feeding habits from a saprophytic to a typical holozoic
method is found in parasitic as well as free-living Protozoa, and shows a corre-
sponding close correlation with increasing morphological differentiation. Thus
in the simpler type of flagellates, as in Trypanosoma and Prowazekia, lacking
a definite oral region, and living in the lymph of the blood and the intestinal
canal respectively, nutrition is of the saprophytic type. In some of the tricho-
monads, as in Tetratrichomonas prowazekia (Kofoid and Swezy, 1915), a
definite cytostome is present and food masses are ingested, showing an advance
to a holozoic mode of nutrition. This type of nutrition is accompanied by a
considerable morphological differentiation.

The Protozoa also offer evidences that point to the conclusion that para-
sitism in this group is not always symbolic of morphological degeneracy, but
rather lies often in the upward path of the lines of structural evolution, the
reverse of conditions found in some of the Metazoa. In the Blastodiniidae we
find this illustrated by the tendency to form a somatella.

In this group the life cycle, as shown in Blastodinium pruvoti (fig. J) and
Chytriodinium roseum (fig. IK), becomes increasingly more complex, and the
organism attains a larger size, than is the case in free-living forms (fig. I).
This condition is found to hold in many instances throughout the Protozoa
generally. Among the ciliates the most highly specialized forms are those be-
longing to the Orphryoscolecidae and living in the stomach of ruminants, such
as Diplodinium (Sharp, 1914).

Another group which presents increasing evidences of complexity in the
life cycle and in anatomical features, which may even be carried to the extent
of forming a somatella of several differentiated cells, as in Myxobolus (Doflein,
1911), is the Sporozoa. These are wholly parasitic, no free-living species being
known.

These two types of nutrition, namely, saprophytic and parasitic, thus seem
to be stages in the natural development of the Protozoa, each marking an
advance along some line. When these are secondarily acquired in higher forms,
however, as in many cases in the Metazoa, such as the parasitic crustacean
Sacculina, the reverse of this is true and this mode of life becomes symbolic of
degeneracy.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 93

RELATIONSHIPS TO THE Merazoa.—The unarmored Dinoflagellata present
two structural differentiations which occur also as distinctive characteristics
of the Coelenterata, namely, nematocysts and tentacles. The nematocysts of
the dinoflagellates are so strikingly similar to those of the coelenterates as to
suggest the close relationship of the two groups of organisms. The tentacle of
the dinoflagellates arises on the border of the sulcus or mouth of these Protozoa
as these organs do around the mouth of the coelenterate.

There is also in the dinoflagellates a tendency to form a multicellular soma-
tella, exemplified in chain-formation in Ceratium, in the corresponding more
temporary phase in Noctiluca, and in the more permanent and more massive
somatellas of the Blastodiniidae. We find in Polykrikos (originally described
as a larval flatworm) a permanent 2- or 4-celled somatella with nematocysts.
The sulci of its adjacent cells or zooids form a continuous mouth capable of
capturing and engulfing other Protozoa, diatoms, and even the ova of Sagitta.

The elemental structures and functions thus presented are suggestive, and
possibly highly significant of the path along which pelagic dinoflagellates may
have given rise to simple pelagic coelenterates in which cell boundaries and
cell layers may have played only a secondary and belated part as the size of the
organism increased. If we could put together in one organism the nematocysts,
the continuous sulei (mouth), and multicellular (multinucleat) somatella of
Polykrikos along with the tentacle of Noctiluca, one for each constituent cell
along the side of the mouth, we should have an organism whose structure would
appear prophetic of the Coelenterata and one whose affinities to that phylum
and to the Dinoflagellata would be patent.

CHAPTER VIII

DISTRIBUTION, LOCAL DISTRIBUTION, HISTORICAL
DISCUSSION

The dinoflagellates are widely distributed in both fresh and marine waters,
from the polar seas to the tropics, reaching their maximum development, numer-
ically as well as in speciation and in structure, in the warm temperate and
tropical regions. No formulation of the laws which undoubtedly govern their
distribution can be attempted at the present time, owing to the utter lack of
anything like adequate records of the occurrence of this group, that is, adequate
from a systematic, distributional or seasonal standpoint. Any conclusions that
may be drawn are therefore wholly provisional.

The thecate dinoflagellates have been more fully investigated than have the
naked forms, but the records here also are incomplete. It is probable that the
two groups are very closely bound together in the temperature and other re-
lations which condition their geographical distribution, but further investi-
gation will be required for the Gymnodinioidae at least before these relations
can be stated with any degree of certainty.

Many of the earlier records of the occurrence of these forms, in both fresh
and marine waters, are of doubtful value, owing to the often contradictory and
poorly defined species characters which usually result in some confusion and
error when records of occurrences of species in a large quantity of plankton
are made. In the case of doubtful species, where these records are unaccom-
panied by figures of the organisms found, the records are sometimes practically
useless.

In plankton forms which have no fixed spatial relations to the substrate the
division into littoral, neritic and pelagic life zones is much harder to maintain
than is the case with those organisms whose connection with the substrate is
even temporary or whose swimming habits afford some resistance to a passive
drifting with the current. Neither of these factors operates to maintain an
established position for the majority of the protozoan plankton, hence we find
the Protozoa more widely distributed through these three zones of oceanic life
than are many other groups. This is true of the dinoflagellates to a very large
extent. yet we find even here a slight tendency towards segregation of more or
less distinct faunal groups.

The Dinoflagellata are typical pelagic organisms, with some cosmopolitan
species and many others of seemingly more limited distribution. They have
representatives which are restricted solely to the high seas or are, at most, found
only as stragglers in coastal waters, as, for example, Ceratocorys, Histioneis,

[94]

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 9

On

and Ceratium ranipes. Others are rather closely restricted to coastal waters
and the neritic fauna, as, for example, Exuviaella, Prorocentrum, Noctiluea,
and Ceratium divaricatum.

In view of the fact that representatives of this order have adapted them-
selves to salt, brackish and fresh waters and even to a parasitic mode of life,
it is rather to be expected that they will be found in other available habitats
as well. ;

The beach sands of the littoral zone offer such a habitat and one, moreover,
which is constantly invaded by coastal waters laden with the neritic fauna.
Whenever the tidal amplitude and the breakers come into play we find an
automatic agency for the incessant stranding of the dinoflagellates of the neritic
zone upon the surface and in the interstices of the beach sands. As each re-
current tide or breaker recedes the sand acts as a filter bed upon which is aecum-
ulated the plankton of the infiltrating water. This accumulating action of the
beach sands is especially noticeable along the California coast whenever the
outbreaks of ‘‘red water’’ due to dinoflagellates occur. At such times the beach
becomes highly phosphorescent with its accumulating, but still living Gonyaulax,
and becomes luminous whenever disturbed by the breakers or by passing foot-
steps.

A typical sand beach form is found in the genus Amphidinium, some of the
members of which have not been recorded thus far from any other habitat.
The occurrence of two or more species of this genus has been recorded by
Herdman (1911, 1912, 1913), who followed for several years their recurrence
on the beaches of the sheltered harbor at Port Erin, Isle of Man, in the Irish
Sea. According to him, these species form a yellowish brown film, rippled by
tidal movements, on the surface of the sands in April, September, October, and
November, almost to the exelusion of diatoms, which abound at other times.
These organisms were abundant from one day to two or even three weeks, after
which they almost completely disappeared. Although abundant on the sands
within tidal limits, these species could not be detected in the plankton of the
immediately contiguous waters.

An examination of the arenaciphilous microfauna and flora at La Jolla also
reveals a number of species which have not been observed in the hauls made
concurrently a short distance offshore, nor have they been discovered in the
pelagie collections made prior to or since these examinations. These exami-
nations were made by rinsing the sands cautiously in fresh sea water, condens-
ing the organism released thereby on filter paper, and examining the sediment
thus collected. In addition to the representatives of the neritic plankton, of
which a few stranded individuals were always present, there appeared to be
an indigenous complex consisting of a few species of naviculoid diatoms, some
small nematode worms and several species of dinoflagellates.

The dinoflagellates discovered in this complex were mainly members of the
genus Amphidinium, as follows: Amphidinium asymmetricum, A, corpulentum,

96 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

A. scissum, A. truncatum, A. dentatum, with one representative each of the
genera Gymnodinium and Gyrodinium, namely, Gymnodinium hamulus and
Gyrodiiium viridescens. We thus find the genus Amphidinium, previously
reported from beach sands by Herdman, represented here by no less than five
common species. It is also suggestive in its bearing on the isolation hypothesis
that we find within this very restricted and fairly uniform habitat, in con-
siderable abundance and constantly intermingled, five species of the genus
Amphidinium, and, moreover, all these appear to be closely related, if structural
similarity may be taken as a clue to relationship. These five species constitute
nearly one-third of the valid species within the genus. A common habitat is
no bar to speciation in this instance. It is also noteworthy that these sand beach
forms present a type that is only rarely met with in the neritic and pelagic
fauna, shown by the strong dorsoventral compression of the body.

The fresh-water species of the dinoflagellates also form another fairly
uniform group, more nearly related to the arenaciphilous species than to either
the neritic or pelagic forms. They are uniformly of a small size, with two
exceptions, Gymnodinium fuscum and G. mirabile, which more closely approxi-
mate the average size among the pelagic group.

The fresh-water species of the Gymnodinioidae thus far described belong
to the genera Hemidinium, Amphidinium, Gymnodinium, and Gyrodinium.
Among the species of the last three genera found in this habitat there is a
notable lack of the more highly specialized species, as well as a complete absence
of the more highly developed genera of the Gymnodinioidae, the fresh-water
forms representing only the more primitive and the more generalized species
of the groups.

The non-thecate dinoflagellates are found in fresh water in all parts of the
globe. Most of the species described, however, have been found in the central
part of Europe, particularly in the waters of Switzerland and neighboring
countries. Complete lists of these will be given in the further discussion of
this subject under each genus and need not be repeated here.

From other parts of the world the records are only fragmentary. A single
one comes from Egypt in the notes of Schmarda (1854), who records the pres-
ence of three species of Peridinium in the Nile River and adjacent waters.
These are probably species of Gymnodinium. From South America the only
representatives of this group of which we have any records are those of
Gymnodinium fuscum and G. viride by Cunha (1913) from Brazil.

In North America a like paucity of observations on the Gymnodinioidae is
found. Cockerell (1907-1910) noted the presence of an unidentified species of
Gymnodinium in the waters at Boulder, Colorado. Conn (1905) also found a
species of Gymnodinium in Connecticut. From Japan, Ohno (1911) has de-
scribed a single species, Gymnodinium biciliatum, and from New Zealand
Maskell (1887) reports G. varians. Three species of Gymnodinium, G. aerugi-
nosiem, G. bogoriense, and G. varians, were observed by Klebs (1912) in Java.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 97

From the English, Scottish and Irish lakes, West and West (1909) record two
species, Gymnodinium paradoxum and G. zachariasi.

These isolated references to the Gymnodinioidae in such widely separated
waters indicate a wide range in their distribution which more complete investi-
gations will undoubtedly greatly enlarge. They are among the smallest of the
fresh-water fauna and hence easily escape observation.

In the marine group of the non-thecate dinoflagellates we find an equally
wide distribution. From the colder waters of the Arctic Pouchet (1894) found
Gymnodinium wilczeki, G. pseudonoctiluca, Pouchetia polyphemus, Polykrikos
schwartzi, and Gymnodinium (=Gyrodinium) crassum. Meunier’s work
(1910) in the Arctic was more exhaustive, but together with the great number
of other forms which he described he figures only three species belonging to
this group, Le., Gyrodinium fusus, G. lachryma, and G. grave.

The remainder of the members of this group, with one or two exceptions
from tropical waters, are all found in the warm or cool temperate regions.
Most of these come from the Atlantic or the bays along the west coast of Hurope
opening into it, including the Mediterranean. In a comparison of the lists of
species given for these waters and the species found by us in the Pacific it is
found that no great differences separate these two regions. Of the eighteen
species of Gymnodinium previously described from this region of the Atlantic,
seven have been found in the San Diego region; of the twenty-one species of
Gyrodinium, six occur at San Diego; of the ten species of Cochlodinium, five
are found at San Diego, and of the six species of Pouchetia, two are present
in this region. This gives a total of fifty-five species of these four genera found
in this region of the Old World, of which twenty have been identified by us in
the San Diego waters, with a total of ninety-two new species present at the same
place. The relative thoroughness of the exploration of these two regions and
seasonal limitations of collections probably accounts for the disparity in these
two series of numbers.

Kofoid (1910a) has pointed out the large proportion of the species of the
thecate dinoflagellates described from other regions and present in the Pacific
off San Diego. The relative proportions are somewhat greater than in the
non-thecate forms. This may be due in part to the fact that observations on
the thecate dinoflagellates have been carried on throughout the entire year for
a number of succeeding years, while observations on the non-theeate forms
have been limited to the months of June, July, and August. It may also be
due to the greater knowledge generally of the thecate forms.

In regard to the seasonal distribution of the unarmored dinoflagellates but
little can be said. Daily hauls have been made at La Jolla throughout the year,
but only those of the summer months have been examined immediately after
being taken. As the Gymnodinioidae cannot as a rule withstand the formalin
used as fixative, the hauls so treated are useless for purposes of identification
of this group, with very few exceptions. Our records, therefore, are complete
only for the months of July and August.

98 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Many species are apparently restricted in their seasonal appearance while
others may be found at all seasons; for example, Lohmann (1908) records the
presence of Amphidinium crassum and A. rotundatwm in the Baltic Sea near
Kiel, Germany, throughout the vear. Other species have been recorded from
two or more places in the same latitude and general temperature conditions for
different months of the year, indicating a wide range of temperature relations.

It has been found in the theeate dinoflagellates, and it is probable that it is
equally true here, that the period of greatest abundance, both specifically and
numerically, extends from June to October or November. During the latter
part of this period many tropical forms are found in the San Diego region,
brought northward by the currents in the Pacific. At other times of the year
drifters from the northern region are sometimes observed here. The occur-
rences of the latter species are influenced by the southbound California current
from more northern waters.

One of the mysteries connected with the distribution of the dinoflagellates
is the sudden occurrence of vast quantities of a single species, so great in
amount as to give a distinct color to large areas of the sea. Such is the red
water frequently noted in patches in the Pacific off the coast of California
during the summer months. This is caused by Gonyaulax polyhedra, or in one
case of red water at La Jolla in 1916 by Prorocentrum micans. In other loeal-
ities species of Ceratium and Peridinium have been known to cause a distinct
coloration of the water.

Gymnodinium flavum was the cause of an outbreak of yellow water at La
Jolla during the summer of 1914. This was not very great in extent or serious
in its results. This sudden appearance of vast numbers of a single species and
an almost complete disappearance a few days later has no apparent relation
to tides or currents. Its cause is probably a physiological one, and may be the
response of a peculiarly susceptible organism to the stimulus of a sudden influx
of materials present in their normal habitat in only limited quantities. The
susceptibility of Dinoflagellata to extremely minute amounts of mineral sub-
stances is shown by the fact that one part in ten million by weight of copper
sulphate is sufficient to kill off utterly within a few days all Ceratiwm hirundi-
nella in California fresh-water reservoirs. The effect of this algicide is lasting,
for months at least. It is theoretically possible that these may be not only
growth depressants but excitants as well, the existence of which in minute quan-
tities would suffice to set in motion and to continue such massive changes in
production as appear in the red water, where the tonnage per acre is enormous.
The possibility that such specific growth excitants exist among the organic sub-
stances accumulated by the processes of decay in the depths of the sea and near
the light floor of the high seas is suggested by the fact that red water areas lie
along our western coast where upwelling waters enrich the coastal region, and
that the greatest abundance of the dinoflagellates, both of individuals and of
species, in the ocean lies suggestively near the zone of initial decay of the
phytoplankton.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 99

Locat DistripuTion.—The data for an adequate discussion of this phase of
distribution of these pelagic organisms is wholly inadequate for two reasons.
In the first place, there are no data from contiguous regions, and secondly, the
species herein discussed were progressively discovered and allocated, so that
within our own data the facts as to distribution are limited.

It will appear to the reader of the systematic section of this work that very
few individuals have been seen of most of the species herein described, whereas
the facts are that only those individuals are cited whose specific identity is
recorded in drawings or was determined and recorded during the searching of
the plankton. In the course of the investigation there were very many instances
of species not recorded or not run down on the slide until sufficiently quiescent
for certain identification.

The individuals of many of the species are in fact much more abundant
than the data cited indicate.

The following conclusions as to local distribution are based on our obser-
vation and records: (1) The species are very unequally represented in numbers.
Those which may be called common are relatively few. The following were
common in the summer of 1917, or in previous years as noted, Amphidinium
truncatum (1914), Gymnodinium coeruleum (1906), G. costatum (1917) ; G. con-
tractum, G. dogieli, G. flavum (1914) ; G@. gracile, G. hamulus (1914) ; G. hetero-
striatum, G. lunula, G. rubricauda, G. rubrum, G. sphaericum, Gyrodinium
maculatum, G. ochraceum, G. pingue, G. rubricaudatum, Cochlodinium citron,
Torodinium teredo, Polykrikos kofoidi, Noctiluca scintillans, Nematodinium
armatum (1917). Thus 24 species out of a total of 116 are common, while 92
are rare, being represented in a number of instances by records of a single
individual only.

(2) Species are not equally abundant in different years. Thus Gymnodi-
nium flavum was very abundant in 1914, but in no other year. G. coeruleum
was common in 1906, but not in 1917. Polykrikos appears to be rather common
in most years.

(3) There is some evidence as to favored habitats. There is a distinct
arenaciphilous fauna, which we have previously noted, adapted to that region.
There are some species which survive in larger numbers than others in the
immediately neritic waters, as shown in collections at the pier at La Jolla, but
this is doubtless in part due to relative numbers, and may be, in part, the result
of some vertical stratification.

(4) The region of greatest variety in species begins several miles offshore
and is not in the innermost two to three miles. Many species found here
occurred also at the pier, but less frequently and in much smaller numbers.

(5) The number of species taken in surface hauls from the upper two meters
is much less than that taken in hauls from 80 meters to the surface. Hauls
from greater depths do not materially increase the number of species found.

100 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

In our discussion of occurrences we have noted the depth from which the
net was drawn in making the collection. The net was towed for about twenty
minutes at the depth indicated, and then brought open to the surface. The
organisms in the catch may have come from any level.

HISTORICAL DISCUSSION

It is to the epoch-making work of O. F. Miller that we owe our first glimpse
of the members of the dinoflagellate group. The first of these to be discovered
were the fresh-water thecate forms of Ceratiwm hirundinella and a species of
Peridinium. The former he called Bursaria hirundinella and the latter Vorti-
cella cincta (1773). Ina later work (1777) he records the discovery of a marine
species also belonging to the genus Ceratium, as Cercaria tripos. The outlines
of these forms were delineated with a fair degree of accuracy, but it was only
in the species of Peridinium that the girdle was clearly marked.

Miiller was followed by Schrank (1793), who established the genus Ceratium
for a marine form which he designated C. tetraceras.

The most important of these earler observations, however, were those of
Michaelis (1830), who discovered that the phosphorescence of the sea was due,
in a large measure, to these minute forms of animal life. He figured a number
of species, among others Prorocentrum micans, which were later named by
other investigators. He also was the first to observe the longitudinal flagellum,
though mistaking the single one, with its constant activity in a cone-shaped
amplitude of vibration, for several flagella.

In the same year appeared the first of a series of papers by Ehrenberg in
which some attention was given to this group. Like his predecessors, the
organisms which he observed were mainly those of the thecate forms. He de-
scribed the genera Prorocentrum, Glenodinium, and Peridinium, deseribing
under the latter designation species which were later removed to the genus
Ceratium. In addition to these he described Gymnodinium fuscum as a species
of Peridinium. We observed the flagella characteristic of the group, though
figuring the ribbon-like transverse flagellum as a series of cilia. He also figured
the girdle and sulcus.

The first attempt to form a systematic group of the dinoflagellates was also
made by Ehrenberg (1830) in establishing the family Peridinaea for the genera
Peridinium and Glenodinium, to which he later added the genus Dino physis.
This grouping was based on a recognition of the relations of flagella and girdles.

The genus Prorocentrum was not recognized by Ehrenberg as related to
Peridinium, but was placed with the eryptomonads. His interpretation of the
internal structures of these micro-organisms was in line with his conception
of the Protozoa generally as more or less perfect miniature replicas of the
Metazoa. Thus the vacuole he considered as a stomach, the chromatophores as
ovaries, and the nucleus as a prostate gland.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 101

It was also due to the indefatigable labors of Ehrenberg (1854) that the
discovery of fossil dinoflagellates was made. These were mainly species of
Peridinium present in the flints of Delitzsch, belonging to the Cretaceous.

The next landmark in the history of the dinoflagellates was the appearance
of Stein’s monograph in 1878. Between this date and the publication of the
work of Ehrenberg a few contributions were made, chiefly on the thecate forms.
Among these might be mentioned the investigations of Perty (1852) on the
fresh-water species in the Alps and their environs. A few of the forms he
described undoubtedly belong to the Gymnodinioidae, but considerable doubt
attaches to them owing to the lack of adequate figures and descriptions. Also
of interest from a geographical point of view is the work of Schmarda (1854)
on forms from the Nile River and neighboring waters in Egypt.

Of more importance was the work of Claparede and Lachmann (1858-61),
both from a developmental as well as a morphological viewpoint. They estab-
lished the genus Amphidinium and recognized the dinoflagellate affinities of
the genus Prorocentrum. They were the first to note the encysted forms, par-
ticularly the secondary, crescent-shaped cysts of at least two different species,
one of which is undoubtedly Gymnodinium lunula. The flagellated organisms
were oriented by these investigators, as well as by Ehrenberg, with the longi-
tudinal flagellum projecting from the anterior end of the body—the reverse of
its actual relations but in keeping with the conditions found among other
flagellates. The transverse flagellum was also seen as a row of cilia extending
around the body.

Claparéde and Lachmann divided the Protozoa into four orders or tribes:
Ciliata, Suctoria, Cilioflagellata, and Flagellata. The Cilioflagellata comprised
the dinoflagellates and was based on their conception of the motor organelles
of these forms as consisting of both cilia and flagella. This conception of the
ciliate structure of the transverse flagellum was held by later investigators, as
Stein (1878), Bergh (18810), and Saville-Kent (1880-82), until the work of
Klebs (1883) clearly pointed out the error of this interpretation.

With the appearance of Stein’s monograph (1878-83) a new era of investi-
gation on the flagellates was opened. In the twenty-five magnificent folio plates
with which his work is illustrated we find the only accurate representation of
the dinoflagellates that had been put forth up to this time. His figures were
made with the high magnification of from 600 to 1200 diameters or more, hence
his analysis of the finer structures as well as the organization of the body, gave
an entirely new and adequate conception of these organisms, with the exception
of the transverse flagellum, which he still figured as a row of cilia. His work
is also notable for the number of new species which he added to the list of those
previously described. He established the genera Hemidinium and Gymnodi-
nium among the non-thecate forms, but the major part of his treatise relates
to the theeate dinoflagellates.

102 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Along with his clear interpretation of the organization of these flagellates
he reversed the orientation used by earlier investigators and gave to the longi-
tudinal flagellum a posterior trailing position. He also figured the oblique
plane of division in the thecate group and division in encysted individuals of
Amphidinium, without, however, noting the details of the division process.

The period following the publication of Stein’s monograph was a more
prolific one in the investigation of these organisms, both by the addition of new
genera and species and by a more systematic classification of the group.

Bergh (1881b) divided the order Cilioflagellata into two families, the
Adinida, containing Prorocentrum, and the Dinifera. The latter he divided
into three subfamilies, the first, Dinophyida, containing Dinophysis and Amphi-
dinium, the second, Peridinida, for Peridiniwm and related thecate species, and
the third, Gymnodinida, for Gymnodinium, Hemidinium, and Polykrikos. He
thus did not recognize the close relation of Amphidinium and Gymnodinium,
but placed the former with the thecate genus, Dinophysis.

In 1880-1882 Saville-Kent put forth an extensive review of this group,
adding two new species to the genus Gymnodinium. One of his most important
observations was the discovery that these small Gymnodinium with which he was
working were holozoic in nutrition. He also greatly enlarged the boundaries
of the Cilioflagellata to include four families possessing both cilia and flagella,
Heteromastigidae, Mallomonadidae, Stephanomonadidae, and Trichonemidae,
which, he considered, intimately connected the Cilata and Flagellata. These
groups were later recognized as having affinities neither with the dinoflagellates
nor with the ciliates.

The most noteworthy publication on this subject following Stein’s was that
of Bitschli in Bronn’s Klassen und Ordnungen des Thierreichs in 1885. He
pointed out the inadequacy of the earlier term Cilioflagellata and changed it
to the more appropriate name Dinoflagellata, recognizing the true nature of
the transverse flagellum, and gave an exhaustive review of the entire subject.
He had earlier (1873) added the genus Polykrikos to the group, though in his
first description of it he had described it as a ciliate infusorian. Bergh (1881b)
placed it in the Cilioflagellata, and Biitschli accepted this allocation in his
discussion of the Dinoflagellata.

Biitschli, as Bergh had done earlier, also disregarded the distinction between
the thecate and non-thecate forms by placing Gymnodinium and Peridinium
in one family, the Peridinida, Amphidinium with the Dinophysida, and creating
a third family, Polydinida, for the genus Polykrikos.

Pouchet contributed a series of articles on the dinoflagellates from 1883 to
1894, based on studies at Concarneau, on the French coast, adding a number
of new species to those already described. One of these was Oodinium poucheti
(= Gymnodinium pulvisculus), parasitic on Appendicularia. The eycle of de-
velopment which he described for this species was the first attempt as yet made
to work out a complete life history of the dinoflagellates.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 103

Pouchet’s industry and his exceptional opportunities at Concarneau for
studying the living dinoflagellates of the marine plankton greatly enlarged our
knowledge of this group, especially of the unarmored forms. He added no less
than fifteen species to the list. Unfortunately for the systematists who followed
him, Pouchet’s pioneer work was so fragmentary and his conception of specific
limits so vague and changeable that his contributions are incorporated with
difficulty in our present system. He added to our knowledge of Polykrikos and
Noctiluca, but became involved in the latter’s puzzling relations to ‘‘ pseudonoc-
tiluca’’ forms, without arriving at any clear conception of the relationships of
Noctiluca to the dinoflagellates. His greatest contribution was his discovery of
the ocellate forms which he included in Gymnodinium, but which now, as
Pouchetia, bear his name. He also contributed to our knowledge of the arctic
dinoflagellates in his account (1894) of the voyage of the ‘‘ Manche”’ and of the
relation of dinoflagellates to the food of the sardine.

Coincidentally with Pouchet’s earliest work (1883) appeared Gourret’s
monograph (1883) on the Marseilles dinoflagellates. This also was a pioneer
enterprise, and beyond recording a few new species and adding greatly to
synonymical perplexities he contributed little to our permanent knowledge of
the group. His conception of the phylogenetic position of Gymnodinium as a
terminal derivative of the thecate Glenodinium and Diplopsalis is the reverse
of what appears sound, and is on a par with his derivation of Amphidinium
from Dinophysis.

The greatest single contribution made to this subject was that of Schiitt,
whose monograph on the dinoflagellates appeared in 1895 as part of the results
of the ‘‘ Plankton’”’ Expedition. Both in the number and variety of forms which
he figured and the careful and painstaking analysis of the structures and proto-
plasmic organization of these flagellates his work stands unrivaled. Seven of
the large folio plates are devoted to the members of the Gymnodinioidae, adding
many new forms to those previously described. He unfortunately omits all
mention of the localities from which his material was obtained, hence his work
has little to offer in the distributional and geographical study of the dinofla-
gellates.

In the following year (1896) the same author revised the system of classi-
fication of the dinoflagellates in Engler and Prantl’s Pflanzenfamilien. He
separated the thecate and non-thecate forms, and in the latter group distin-
guished the genera Spirodinium and Cochlodinium, with Pouchetia, a genus
which he had established the preceding year. The entire group he divided into
three divisions, the Gymnodiniaceae for the non-thecate forms, the Prorocen-
traceae and the Peridiniaceae for the thecate. With the Gymnodiniaceae he
placed the genus Pyrocystis, which had been described by Murray in 1876. In
thus recognizing the systematic value of the distinction between the thecate and
non-thecate dinoflagellates he laid the basis of the present system of classifi-
cation. Klebs (1912) returned to the older system in placing the genus Amphi-
dinium in the Prorocentraceae. He also removed the thecate Glenodinium

104 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

from the group with which it naturally belongs, the Peridiniaceae, where it had
been allocated by Schiitt, and placed it in the Gymnodiniaceae. Having a dis-
tinct theea, it is sharply marked off from the dinoflagellates belonging to the
Gymnodinioidae ; and we therefore follow Schiitt’s allocation and reject it from
that group.

Other reviews of this group have appeared in which no new contributions
were made, such as those of Delage and Hérouard (1896), Schonichen and
Kalberlah (1900), and Paulsen (1908). Lemmermann (1910) included the
Peridiniales in his work on the Algae, and in 1913 Schilling issued a monograph
on the fresh-water dinoflagellates which, though short, is both comprehensive
and accurate.

The single contribution of Dogiel (1906) is important in that he followed
out the life history of two species of dinoflagellates, the free-living Gymnodi-
nium lunula, and a species parasitic on copepod eggs, Chytriodinium roseum
(Gymnodinium roseum). He also figured division in Gymnodinium hetero-
striatum (=G. obtusum), showing that this process follows an oblique plane
similar to that found in the thecate dinoflagellates.

Our further knowledge of the parasitic dinoflagellates is due to the efforts
of Chatton, who published a series of papers from 1906 to 1912 dealing with this
highly interesting though small group.

The most illuminating and constructive treatment of the dinoflagellates, and
one in which the unarmored types are adequately discussed, is that found in
the chapter on Peridinieae in West’s monograph (1916) on the Algae in the
Cambridge Botanical Handbooks. Although of necessity brief, it is compre-
hensive and deals with the upstanding facts of the organization of this group
ina masterly way. He correctly, in our view, places the Gymnodiniaceae near
the base of his evolutionary scheme and independent of the Prorocentraceae,
which he also places low in the seale. His derivation of Dinophysis from Proro-
centrum seems to us less probable than one from an Amphidinium-like ancestor,
and the inclusion of the Pyrocystaceae as an independent family we regard as
untenable on the ground that Pyrocystis is, or will be found to be, a phase in
the life history, a phase which, for a longer or shorter period, may be expected
in most, if not all, free-living dinoflagellates. Furthermore, his conception of
the Dinoflagellata as a group within which the distinctions between holozoic and
holophytie nutrition have not become clearly established along definite system-
atic lines is eminently correct. We dissent, however, from his conclusion that
‘‘the saprophytic Peridinieae are probably mostly degenerate forms,’’ and be-
lieve that the facts justify the conclusion that both saprophytic and holozoic
nutrition play a much larger part in the evolution, past and present, of the
Dinoflagellata, especially of the unarmored forms, than the evidence, hereto-
fore at hand, has seemed to indicate. The estimate that ‘‘90 per cent of them
are true vegetable organisms with a holophytic nutrition”’ may be true of fresh-
water forms of the group with which the author is so familiar, but it certainly

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 105

can not apply to the Gymnodinioidae, nor to the deep-water, marine represent-
atives where the saprophytic mode of nutrition tends to prevail.

Many other investigators have added details to our knowledge of the
speciation, organization and geographical distribution of the non-thecate dino-
flagellates, but further discussion of these will be reserved until the history of
each group or species is taken up.

CHAPTER Ix

CLASSIFICATION OF THE DINOFLAGELLATA

Regnum Animalia
Phylum 1. Protozoa Goldfuss
Superclass 1. Plasmodroma Doflein
Class 1. Flagellata Cohn emend. Biitschli sive
Mastigophora Diesing
Subelass 1. Dinoflagellata Biitschl
Order 1. Adiniferidea Kofoid and Swezy
Tribe 1. Athecatoidae Kofoid and Swezy
Genus 1. Haplodiniwm Klebs
Tribe 2. Thecatoidae Kofoid and Swezy
Family Prorocentridae Kofoid
Order 2. Diniferidea Delage and Hérouard emend.
Tribe 3. Gymnodinioidae Poche emend.
Family 1. Protodiniferidae Kofoid and Swezy
Genus 1. Protodinifer Kofoid and Swezy
2. Oxyrrhis Dujardin
Family 2. Gymnodiniidae Kofoid
Genus Hemidinium Stein
Amphidinium Claparéde and Lachmann
Gymnodinium Stein emend.

Cochlodinium Schutt
. Torodinium Kofoid and Swezy
Family 3. Polykrikidae Kofoid and Swezy
Genus 9. Polykrikos Biitschli emend.
Family 4. Noctilucidae Saville-Kent
Genus 10. Pavillardia Kofoid and Swezy
11. Noctiluca Suriray
Family 5. Pouchetiidae Kofoid and Swezy
Genus 12. Protopsis Kofoid and Swezy
13. Nematodinium Kofoid and Swezy
14. Pouchetia Schiitt emend.
15. Proterythropsis Kofoid and Swezy

3
4
5
6. Gyrodinium Kofoid and Swezy
7
8

16. Erythropsis Hertwig

[106]

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 107

Family 6. Blastodiniidae Kofoid and Swezy
Genus 17. Apodinium Chatton
18. Blastodinium Chatton
19. Chytriodinium Chatton
20. Ellobiopsis Caullery
21. Oodinium Chatton
22. Paradiniwm Chatton
23. Schizodinium Chatton
24. Syndinium Chatton
25. Trypanodinium Chatton
Family 7. Cystodiniidae Kofoid and Swezy
Genus 26. Cystodinium Klebs
27. Dinamoeba Pascher
28. Glenodinium Klebs
Tribe 4. Amphilothioidae Kofoid and Swezy (doubtfully Dinoflagellata)
Family 8. Amphilothiidae Kofoid
Genus 29. Amphilothus (Schitt)
Family 9. Gymnasteriidae Poche (doubtfully Dinoflagellata)
Genus 30. Gymnaster Schitt
31. Achradina Lohman
32. Monaster Schitt
Tribe 5. Peridiniidae Kofoid and Swezy
Subclass 2. Cystoflagellata (Haeckel) emend., Kofoid and Swezy
Tribe 6. Cystoflagelloidae Kofoid and Swezy
Family 10. Leptodisciidae Kofoid
Genus 33. Leptodiscus Hertwig
34. Craspedotella Kofoid

Subclass DINOFLAGELLATA Biitsehli

Cilioflagellata Claparéde and Lachmann (1858-61), pp. 72, 78, 392-412.
Cilioflagellata, Bergh (18816), pp. 177-288.

Cilioflagellata, Saville-Kent (1880-82), pp. 489-469.
Arthrodele Flagellaten Stein (1883), pp. 1-30.
Dinoflagellata Biitschli (1885), pp. 906-1029.

Peridiniales Schiitt (1896), pp. 1-30.

Dinoflagelliae Delage and Hérouard (1896), pp. 373-388.
Peridiniaceae Schénichen and Kalberlah (1900), pp. 227-234.
Dinoflagellidia Kofoid (1907), p. 164.

Dinoflagellata, Doflein (1911), p. 325.

Dinoflagellata, Poche (1913), p. 160.

Dinoflagellatae Schilling (1913), pp. 1-64.

108 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

DiaGnosis.—T wo flagella, one longitudinal, threadlike, usually posterior,
trailing, the other ribbon-like and held transversely; girdle and sulcus more
or less well developed; contractile vacuole absent ; body either naked or covered
with a seulptured shell. Colonial organization in ephemeral or permanent
chain is sometimes found. The life cycle may show a greater or less extent of
polymorphism.

This subclass contains 2 orders.

Key To OrDERS OF THE DINOFLAGELLATA

1. Body either naked or with a bivalve shell, without well developed girdle or suleus -.................
Sioa he Abe So) a ee a ag ee me ee Adiniferidea nom. nov.

2. Body either naked or covered with a sculptured shell, girdle and suleus present at some stage
ofthe lifevcycle:t-= = er Se ee ae ee Diniferidea Delage and Hérouard

Order DINIFERIDEA Delage and Hérouard emend.

Dinifera Bergh (1881b), p. 273. Family.
Diniferida Delage and Hérouard (1896), p. 381.
Diniferida, Kofoid (1907a), p. 164.

Dinifera, Doflein (1911), p. 325.

Peridiniidea Poche (1913), p. 161. Suborder.

Dracnosis.—This is a large group with a wide range of characteristics. The
body may be naked or covered with a plain or sculptured shell or theca, con-
tinuous or composed of discrete plates; girdle and sulcus are well developed
and always present at some period of the life cycle; nutrition may be holophytie,
saprophytic, holozoic or parasitic; colorless to highly colored; ocelli and nemat-
ocysts sometimes present. The life cycle is usually complex, sometimes showing
two distinct stages. Division is typically oblique. Sexual processes still obscure
except in Noctiluca. Fresh water and marine. This order contains four tribes.

Key To Tripes oF DINIFERIDAE

1. Body naked, girdle and suleus distinct at some period of the life cycle..Gymnodinioidae Poche

bo

. Body with superficial or more deeply embedded skeletal elements, without enveloping cuirass
Sideline asus Sonate ce sd eos eR DORR cs ou Ree nese eae ed Amphilothioidae nom. nov.

3. Body naked without skeletal elements, girdle and suleus suppressed. .........-.....--------------------------
Shae cascead Dac b2tne desc ot Ae ee a eae Cystoflagelloidae nom. nov.

4. Body with theca composed of a continuous membrane or of discrete plates, epitheca and
hypotheca separated by the girdle plates. ...........--..:.--.--.-sc-ceeseeeseeeo-- Peridinioidae nom. noy.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 109

Tribe 3. GYMNODINIOIDAE Poche emend.

Gymnodiniaceae Schiitt (1896), p. 1.
Gymnodinina Kofoid (1907a), p. 164.
Gymnodiniaceae, Klebs (1912), pp. 488-443.
Gymnodinioidae Poche (1913), p. 161.
Kyrtodiniaceae Schilling (1913), p. 12.

Dracnosis.—Dinoflagellata with temporary or permanent longitudinal and
transverse flagella, located respectively in sulcus and girdle; flagellar pore or
pores ventral; cell body without a theca composed of discrete plates, naked or
enclosed temporarily or constantly in a continuous, homogenous, gelatinous or
cellulose cyst wall usually without a girdle. Fresh water and marine; holo-
phytic, saprophytic, holozoic, or parasitic. This group contains 7 families and
30 genera.

DISCUSSION

This tribe as described by Poche (1913) contained two families, the
Pyrocystidae and the Gymnodiniidae. The family Pyrocysteae was created by
Schiitt (1896) for the genus Pyrocystis Murray, to which he added, as P. lunula,
the form he had described the year before as Gymnodinium lunula. Under
the latter name encysted forms of various species of dinoflagellates have been
figured as one species. A comparison of the figures of Pouchet (1885, pl. 2,
fig. 3), Schiitt (1895, pl. 25, figs. 80., 80:), Blackmann (1902, pl. 4), Wright
(1906, pl. 1, figs. 3-6), Dogiel (1906, pl. 1), Okamura (1907, pl. 5, figs. 32a-c),
and Apstein (1909, fig. 1) will plainly show that specific and even generic dif-
ferences exist between some of the individuals thus figured. Schiitt’s figure
80s, plate 25, gives evidences of having a porulate theca.

We have pointed out elsewhere our views of the limitations of the species
Gymnodinium lunula (p. 229). The allocation of the remaining members of
the old genus Pyrocystis with their genetic relationships cannot be determined
until their complete life histories have been investigated, since these are prob-
ably only phases of the life cycles of other dinoflagellates, both of the thecate
and non-thecate types.

Klebs (1912) has further added to the confusion of this group of organisms.
He changed the family Pyrocysteae Schiitt to Phytodiniaceae, excluding from
it the species Gymnodinium lunula (Pyrocystis lunula Schiitt), and enlarged
it to include four new genera, Phytodinium, Tetradinium, Stylodinium, and
Glocodinium. The four new genera thus added may be dinoflagellates, but as
they have been figured by Klebs they present none of the dinoflagellate charac-
teristics and none of the characters of the genus Pyrocystis Murray except the
outer wall. They seem more nearly related to the Conjugatae or Chlorophyceae
than to the dinoflagellates as that group is at present constituted. Development

110 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

of these forms has not been followed out, neither have dinoflagellate stages been
found. There seems to be, therefore, at present no reason for including them
in the Dinoflagellata, though Poche (1913) recognized them as constituting part
of the five valid genera in the family Pyrocystidae.

With the elimination of these genera proposed by Klebs, as not dinoflagellate
in character, and the elimination of the genus Pyrocystis as composed of stages
in the developmental cycle of other genera, there is no reason left for the con-
tinued existence of the family Pyrocystidae Poche, and we therefore discard it.

The second family of the Gymnodinioidae as established by Poche contains
all the remainder of the non-thecate dinoflagellates. This is a large group and
comprises within itself several smaller groups of closely related genera. The
simplest of these forms is perhaps Oxryrrhis Dujardin. With its poorly de-
veloped girdle and sulcus it is not closely related to Gymnodinium or to other
members of the Gymnodiniidae, but forms one of the connecting links between
this family and the Adiniferidea. We therefore separate it from the Gymno-
diniidae and place it in the family Protodiniferidae, together with Protodinifer.

A second natural grouping is found in those genera which possess an eye-
spot or ocellus. These represent a more advanced stage of development without
closely intergrading forms between them and the Gymnodinium group. Hence
the separation of these genera in a distinct family, the Pouchetiidae, seems
appropriate both from a morphological as well as an evolutionary standpoint.

Still further removed from these three families is the group of parasitic
genera. The acquisition of parasitism alone is not sufficient to separate a
protozoan from the remainder of the forms to which it is closely bound by
structural and developmental similarities. In the case of the parasitic dino-
flagellates, however, this has resulted in profound modifications of the structure
of the body as well as in its development. These seem to be sufficient to mark
off the genera thus characterized as a separate family. To that end the family
Blastodiniidae has been formed for the parasitic dinoflagellates.

Equally distinct from a morphological viewpoint are those dinoflagellates
which have a well developed tentacle. To this group belongs Noctiluca, which
has heretofore been placed in the Cystoflagellata Haeckel. The discovery of
the genus Pavillardia, with its well developed girdle and sulcus as well as ten-
tacle, and of Hrythropsis with a still further development of the tentacular
region into a prod with protractor and retractor fibrillae, bridges the gap which
had earlier separated Noctiluca from the remainder of the dinoflagellates. Two
of these genera fall within different families; Protodinifer, as one of the simpler,
is referred to the Protodiniferidae, and Hrythropsis to the family Pouchetiidae
beeause of its ocellus. This leaves the two remaining genera, Pavillardia and
Noctiluca, in the family Noctilucidae Saville-Kent.

The genera Phytodinium, Tetradinium, Stylodinium, and Gloeodinium,
erected by Klebs (1912), are excluded by us from the Gymnodinioidae. There
is considerable doubt in our minds as to their close relationship with the

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 111

Dinoflagellata. Pending the demonstration that they have in their life cycle
a true dinoflagellate phase it seems best to hold them in suspense. We have
accordingly omitted detailed treatment of this family in this monograph.

The genera Cystodinium and Hypnodinium of Klebs (1912) appear to share
with Glenodinium the peculiarity of having a thin structureless theca closely
adherent to the cytoplasm in the free stage where known. We therefore exclude
them from the Gymnodinioidae and from this monograph.

Key To THE FAMILIES OF THE TRIBE GYMNODINIOIDAE

1. Girdle and sulcus feebly developed, both flagella nearly threadlike, not parasitic, no
tentacle, no ocellus, no cell membrane, not permanently colonial 22...
si RSE a ee a eer eR Protodiniferidae fam. noy.

1. Girdle and suleus well developed, transverse flagellum ribbon-lke, permanently colonial 2
Dr NOPRDETMAneN tly (COLONIA pe ae koa sans aces cu epee tone bgp step teeeecb ecb secoewatese Aen eee race tanane 3
2. Permanently colonial, with nematocysts ............-..-.-.--2-.-2--------0-------- Polykrikidae fam. noy.
SRE OmOCe seme eer ee ee ee eee ee 4
SSHRC) COUTTS PDE CSEING reer eae, ae ance eecaeascec er cece ease nsanacnteee Pouchetiidae fam. nov.
EN TN) SHOT) es ee ee ee eee re 5
Gk. Merny Toueseaetrs, wae) LCN UWS) eer re Noctilucidae fam. nov.
EB TITY OEMEEEISH ECG) eee Gymnodiniidae Poche
Fee aA ETC ha ty SOT ey SUA Le peers eo areas or eee ne ee ene eee Blastodiniidae fam. nov.

Family 1. PROTODINIFERIDAE fam. nov.

Dracnosis.—Gymnodinioidae with rudimentary girdle and sulcus; flagella
anterior or ventral; ocellus lacking; tentacle more or less well developed.
Length. 10 to 50. Marine; neritic from warm temperate waters; 2 genera.

DescripTion.—This family contains representatives of the most primitive Gymnodinioidae
and forms a connecting link between the Diniferidae and the Adiniferidae. The rudimentary
girdle and sulcus and the anterior or ventrolateral position of the flagella, as distinct from the
entire absence of girdle and sulcus and the anterior position of the flagella in the Adiniferidae,
links this family with the Diniferidae rather than with the more primitive Adiniferidae.

In the development of the girdle and sulcus in this family two distinct stages are present.
In Protodinifer these structures are found as the merest rudiments anteriorly located, with the
girdle less than one-half the circumference of the body in length and faintly outlined. In
Oxyrrhis the girdle or groove is ventrolateral and extends nearly or quite around the body, with
a well defined border on the anterior margin, the posterior one sloping away to the narrowed
posterior region of the body. In Protodinifer a tentacle springs from the suleal region and
extends anteriorly some distance beyond the apex of the body. In Oxyrrhis the tentacle-like
projection also arises from the sulcal area in the region of the two flagellar pores, but its length
seldom exceeds one-half the distance between the pores and the antapex. It also appears to be
attached to the suleal area for part of its length. The origin and position of the two structures
are essentially the same in both genera.

112 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The body is asymmetrical with no appreciable torsion in either genus. The nucleus is gen-
erally found near the center of the body with its chromatin contents arranged in characteristic
moniliform strands. Nutrition is holozoic or saprophytie.

This family contains two genera, Protodinifer and Oxyrrhis, with a single species in each.

Key To GENERA OF Protodiniferidae
1. Girdle short, faintly outlined, tentacle long, flagella anterior —............. Protodinifer gen. nov.

2. Girdle nearly or quite 1 circumference in length, tentacle short, flagella ventrolateral _.......
Socata Rk Na EE I ae Te oe Oxyrrhis Dujardin

PROTODINIFER gen. noy.
Plate 7, figure 74; text figure R, 2

Diacnosis.—Protodiniferidae with anteroventral tentacle and sulcus, feebly
developed anteriorly located girdle, long threadlike transverse and short longi-
tudinal flagellum; no lens or pigment; no large hydrostatic vacuoles, small
flagellates, marine.

This genus contains two species, both marine, Protodinifer tentaculatum
sp. nov., the type species of the genus, and P. marinum (Lohmann). The latter
is provisionally transferred here from Rhynchomonas on the basis of its morph-
ological features other than the very essential primitive girdle and sulcus and
the beaded chromatin in the nucleus, features which are as yet undetermined
in this species.

The genus Rhynchomonas Klebs is based on a species (2. nasuta) from
fresh water whose nucleus is of the vesicular type. This flagellate has an
asymmetrical proboscis-like tentacle and a trailing flagellum. It thus super-
ficially resembles Protodinifer, whose relationships to the Dinoflagellata are
revealed by its nucleus with its moniliform chromatin network.

Key TO THE SPECIES OF Protodinifer
Mentacleystou baler ctw fas 0 clave 4 pag eee ae eee ee ae tentaculatum sp. nov.

Mentacleslenders lenothisof sb Od iva sl 0 ripe eee eee ree ma ee marinum (Lohmann)

Protodinifer tentaculatum sp. nov.
Plate 7, figure 74; text figure R, 2

Diacnosis.—A small species with fusiform body, its length 2.45 transdi-
ameters; girdle near apex, feebly developed and evanescent; sulcus scarcely
evident; longitudinal flagellum short; apex modified in the form of a stout
mobile tentacle 0.22 of length of body in length; color greenish grey to pale
ochraceous. Length 54. Pacific off La Jolla, California, July, August.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 113

DEscrIPTION.—The body is stout fusiform, widest posteriorly, apex acuminate, tapering some-
what anteriorly, its length, including the tentacle, 3.8 transdiameters at the girdle. It is sub-
circular in cross-section but flattened somewhat ventrally in the anterior half. The hypocone is
3.3 transdiameters in length or 7 times the length of the epicone. The antapex is contracted
to a stout subconical or slender acuminate horn 0.5 to 1 transdiameter in height. The epicone is
comparatively minute, about 0.5 transdiameter at the girdle in height, subconical with convex
sides and blunt antapex, which in one ease was slightly bifurcated without any accompanying
evidences of mitosis.

The girdle is rudimentary, scarcely visible, and in individuals from collections which have
stood for some hours in the laboratory it wholly disappears. It is located far anteriorly at 0.15
of the total length of the body from the apex. It lies in a transverse plane and is developed
from the pore of the transverse flagellum distally only about 0.25 of the circumference. It is
the merest shallow rounded trough, without marked lips, ridges or list of any sort. The trans-
verse flagellum lies habitually in this girdle and continues in its plane to encircle the body. Its
full length completely encircles the body, though its distal end is sometimes spasmodically thrown
anteriorly and brought back into place. As the animal grows moribund this flagellum falls away
from its habitual position as in other dinoflagellates. It is a very narrow ribbon with well marked
basal axis and characteristic short undulations which travel incessantly towards its distal end.

The fully developed suleus runs from the flagellar pore anteriorly to the apex as a rather
deep trough, sometimes laterally overhung by the edges. It is straight, shows no separate pore
for the longitudinal flagellum and encloses the base of the stout tentacle, which merges into its
dorsal wall. A denser tract passes posteriorly for a short distance into the cytoplasm from its
base. The suleus does not extend posteriorly upon the hypocone.

The longitudinal flagellum of this species has been reduced to a short lash, and in its place
an anteriorly directed tentacle has been developed, which is the most striking characteristic of
the organism. This is a stout rodlike structure projecting about 0.25 of the length of the body
beyond the apex. It is cylindrical, of equal caliber throughout and terminates bluntly in a
squarish tip. A differentiated axial core of greater density traverses its entire length.

The cell contents consist of a very indistinct nucleus located in the anterior half of the body
and food masses. The nucleus is ellipsoidal in form with its major axis running from the right
anteriorly to the left posteriorly. It is traversed longitudinally by coarse, nodulated chromatin
threads, about ten on one face. Posterior to this, and filling the posterior half of the hypocone,
is a large, subspheroidal, dull orange-yellow food body with several adjacent smaller spheres.
In some individuals this is broken up into a number of smaller spherules. In still others a cloud
of small, rounded, elliptical, or rodlike, dark olive granules surrounds the anterior half of a food
body in a broad irregular band. A cluster of highly refractive, spherical oil droplets fills the
antapical cone and several linear greenish rodlets, or a single large stout one, lie near the flagellar
pore. The pinkish pusule lies posterior to the pore in the median line and is connected with the
pore by a slender canal. The general color of the cytoplasm is a greenish grey, with a yellowish.
or ochraceous tone anteriorly. There are no striae on the surface and no scattered vacuoles or
droplets of pigment.

Dimensions.—Length, 54; transdiameter, at the girdle, 13+, at the widest
part of the hypocone, 231; length of tentacle beyond the apex, 16v.

VaRIATION.—The principal variations noted are due to the size of the in-
gested food bodies. When this is large the posterior third is somewhat dis-
tended. In one case the antapex was much more acuminate than in the others.
It is not metabolic to any considerable degree, the only changes of this sort
noted being a tendency to form a constricted ring around the base of the tentacle.

114 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

OccuURRENCE.— Described from four individuals taken in a plankton haul
made witha No. 12 silk net from forty fathoms, six miles off La Jolla, California,
in the California Current, July 2, 1917, in surface temperature of 21°95 C.
It was observed also on July 20, 6 miles offshore, July 25, 11 miles offshore,
July 27, 4 miles offshore, and August 13, 0.75 mile offshore, in surface temper-
ature varying from 21°95 to 22°45. It was also taken on July 12 and 20, 1906,
in surface hauls off La Jolla made between 5 and 6 a.m.

Activities.—The tentacle is habitually held in a somewhat rigid position,
directed anteriorly, with a slight dorsal curvature. In moribund individuals
it is gently waved to and fro in a short are intermittently. When in a more
active condition the flagellum is energetically raised to the horizontal plane
and thrust back in a quick stroke which drives the animal backward with a
sudden dart.

The behavior of the animal under the cover glass is generally, however, of
a somewhat different nature. It moves with little rotation in a clockwise spiral
anteriorly for short periods intermittently, with an occasional dart posteriorly.
This posterior movement is an unusual one among dinoflagellates, and there
seems to be no other motor organ than the tentacle to accomplish it. The sup-
pression of the function of rotation may be due to the imperfect girdle and the
varying position of the transverse flagellum.

Comparisons.—This genus is unique among the tentacle-bearing dinoflagel-
lates in the anterior position of the girdle, and in the exceedingly rudimentary
stage of development of this characteristic feature of the order. In Erythropsis
agilis Hertwig the girdle is as well developed as in Pouchetia, and the tentacle
or prod is relatively very much larger. In addition this genus is provided with
a prominent lens and pigment mass. In Pavillardia tentaculifera the tentacle
is quite similar in size and shape to that in Protodinifer, but it is colored a
brilliant brown, as is the pigment in Pouchetia rosea, and the girdle and longi-
tudinal furrow are of the Gyrodinium type. In-Gymnodinium pseudonoctiluca
the girdle is complete and located far anterior and the tentacle is proportion-
ately longer than in Protodinifer.

From these comparisons it is evident that the genus is not closely affiliated
with any of the other tentaculate dinoflagellates. It resembles Hemidinium
and Noctiluca in the incompleteness of the girdle, but the former is an isolated
fresh-water genus in which little speciation has occurred, while this one feature
exhausts its resemblances to Noctiluca. The simplicity of structure places
Protodinifer at the lowest level of the tentacle-bearing dinoflagellates. The
anterior position of the flagellar pore and the very slight differentiation of the
two flagella, the proportions of the body and the coloration are strongly sug-
gestive of a relationship to Prorocentrum. It lacks, however, all trace of a
theca and must be regarded as an athecate representative of the Diniferidae
of primitive type from which the Adiniferidae are an offshoot. The feebly
developed sulcus and girdle are indicative of tendencies which, if accentuated,

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 115

would lead to the higher Diniferidae. It forms a connecting link between the
Adiniferidea and the Diniferidea and supports the monophyletic origin of the
Dinoflagellata.

Protodinifer marinum (Lohmann) Kofoid and Swezy

Rhynchomonas marina Lohmann (1902), pp. 7, 48, pl. 2, figs. 42-45; (1909), p. 223, fig. 4,
nos. 36, 37.
R. marina, Liihe (1913), p. 261, fig. 266.

DiaGnosis.—Elongate fusiform or pyriform, length 2.6 diameters, tentacle
slender, 0.25 length of body in length; length, 12-40". Marine.

Description.—Lohmann (1902) gives a brief description and a few incomplete figures which
afford the basis for the following account. Body fusiform in free state, length 2.1-2.6 times
greatest diameter which may be equatorial or in the posterior third of the body. A tendency to
become pyriform and enlarged posteriorly is seen in the smaller individual and in eneysted and
contracted stages. No trace of a girdle was figured or recorded. The slender tentacle is in all
eases figured as terminal and no suleus is clearly shown. Only a single posteriorly directed
flagellum is figured. This is nearly 1.4 the length of the body in length. In the so-called young
stage the tentacle is figured as stout, much lke that in P. tentaculatum. No nucleus is deseribed,
but a spheroidal yellow body quite similar to that in P. tentaculatum is located posteriorly. A
few large refractive spherules occur in the rounded antapical region and a cluster of smaller
refractive corpuscles lie anterior to the yellow body. A flask-shaped pusule is found near the
anterior end of the body.

Encystment oceurs with the formation of a thin, closely adherent membrane from which the
tentacle protrudes. The cyst later expands into a sphere and the body takes on a stout pyriform
shape within it.

Divensions.—Length, 12 to 404; greatest diameter, 5 to 17; tentacle, 2 to 10+.

OccURRENCE.—Reported by Lohmann (1902) from the plankton in the Bay
of Kiel and later in 1909 in the food contents of the digestive tract of A ppendi-
cularia from the Baltic and Mediterranean seas, but not explicitly from the
latter.

Comparisons.—This species differs from P. tentaculatum mainly in size.
It ranges from 12 to 40, while the specimens of the former species are 54“ in
length. The tentacle also appears to be more slender and to be terminal, but
Lohmann’s figures may not be critical on this point. It also has a body of a
more slender type and a longer transverse flagellum. Lohmann does not figure
the minute longitudinal flagellum if there be one. The resemblance to Proto-
dinifer is so striking that we are led to transfer the species from Rhynchomonas,
where Lohmann placed it, to Protodinifer in the face of the facts that that
author did not note any trace of a girdle, any longitudinal flagellum, or any
nucleus. This may prove to be of the dinoflagellate type with beaded chro-
matin. We saw no individuals of P. tentaculatum with the very slender tentacle
which Lohmann figures for this species. The two species are close together
and may prove to be identical. However, with our present knowledge, the
differences in size, tentacle, and flagellum are such as to lead to specific
separation.

116 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

SynonymMy.—Lohmann originally described this species as Rhynchomonas
marina. However, R. nasuta, the type species of Kleb’s genus Rhynchomonas
(1892), does not have the beaded chromatin nucleus characteristic of the Dino-
flagellata, as shown by the investigations of Belar (1915), nor are the tentacles
of the two species, R. nasuta and R. marina, as nearly alike as those of Proto-
dinifer tentaculatum and P. marinum. We do not know the nuclear structure
of Lohmann’s species. We assume on the basis of the other morphological
features that it will prove to be of the dinoflagellate type and make the generic
transfer thereon to Protodinifer. If it does not have such a nucleus it should
not be transferred here.

OXYRRHIS Dujardin

Text figure R, 3
Oxyrrhis Dujardin (1841), pp. 346, 347, pl. 5, fig. 4.
Oxyrrhis, Diesing (1850), p. 58; (1865), p. 79.
Glyphidium Fresenius (1865), pp. 83, 84, figs. 4-10.
Glyphidium, Cohn (1866), pp. 295, 296, pl. 15, figs. 36, 37.
Oxyrrhis, Saville-Kent (1880-82), pp. 426-428, pl. 24, figs. 53-61.
Oxyrrhis, Biitsehli (1885), p. 845, pl. 45, fig. 12.
Oxyrrhis, Senn (1900), pp. 136, 137, fig. 93; (1911), pp. 606-643, pl. 35, figs. 1-4.

DraGnosis.— Body subovoidal, asymmetrically contracted on the left poster-
iorly; girdle postmedian, incomplete distally, lacking postmargin; sulcus
spreading posteroventrally, divided anteriorly by pendant tentacular lobe;
transverse flagellum originating to the left and the longitudinal to the right of
the lobe; nucleus with beaded chromatin; marine.

RELATIONSHIPS.—The nuclear structure with its very characteristic beaded
chromatin, clearly demonstrated in the researches of Keysselitz (1908) and
Senn (1909), establishes beyond question the dinoflagellate affinities of this puz-
zling flagellate. The oblique (almost transverse) fission, the subsequent chain
formation by the two schizonts, the posteriorly directed longitudinal flagellum,
and the partially developed girdle support this interpretation. There is need
of further research on the structure and behavior of the transverse flagellum
and of the tentacular lobe.

The dinoflagellate affinities of Oxyrrhis have been pointed out by Senn
(1909a, b) on the basis of the nuclear structure and general morphology, and
by Jollos (1910) on the ground of the nucleus alone. This relationship was
first suggested, however, by Bitschli (1885), who called attention to the fact
that Oxyrrhis had the dinoflagellate type of nucleus and posteriorly directed
flagella. He also noted the difference between the two flagella and concluded
that Oxyrrhis might be regarded as a form intermediate between the Crypto-
monadina on the one hand and the Dinoflagellata (Hemidiniwm) on the other.
Unfortunately this view had not been incorporated in his earlier (1885) mono-
graph where Oxryrrhis was included in the Cryptomonadina. Delage and

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA say)

Hérouard (1896) assigned it to the Heteromastigina and Senn (1900), in his
earlier monograph of the flagellates, placed it in the Bodonaceae. Poche (1913
does not allocate it in his ‘‘ System der Protozoa.”’

The grounds upon which Oxyrrhis may be considered a primitive dinofla-
gellate are its imperfect girdle and its apparent lack of differentiation of the
transverse flagellum into the typical ribbon. The sulcus appears to be incom-
pletely differentiated. The tentacular lobe, however, is a specialized rather
than a primitive feature. It appears to be homologous with the tentacle of
Protodinifer.

The fact that the theeate genus Prorocentrum of the Adiniferidea also has
a projection near the flagellar pore is significant, especially if this group is an
offshoot from lower Diniferidea of which Protodinifer and Oxryrrhis are the
existing representatives. The fact that the tentacle in these two genera is a
mobile organ and the projection of Prorocentrum, an immobile part of the
exoskeleton, need not militate against the homology, for the somewhat mobile
girdle of Gymnodinium is certainly homologous with the zone of girdle plates
in the Peridinioidea. In view of the form and location of this projection in
Prorocentrum it appears that Protodinifer is nearer the Adiniferidea than is
Oxyrrhis, which, in the location and imperfection of the girdle, is much nearer
Hemidinium than is Protodinifer. Oxyrrhis may then be regarded as a
more specialized and higher representative of the Protodiniferidae than is
Protodinifer.

Oxyrrhis marina appears to be the only valid species in the genus. Poche
(1903) described O. parasitica from the coelenteron of the Siphonophora. It is
a minute flagellate with two unequal flagella in the midventral surface. There
is no other evidence of its affinities to Oryrrhis. We therefore agree with
Senn (1911) in excluding it from that genus, pending investigation of its
nucleus and flagella. Scherffel (1900) described another parasitic flagellate
living in the coenobia of Phacocystis globosa, which he called Oxyrrhis phaeo-
cysticola. There is no evidence of a girdle or of a beaded nucleus in his account
or in his figures of this species. There are suggestions in the shape, posterior
brown body, and anterior tentacle-like projection, of relationships to Proto-
dinifer, but more investigation is needed before a decision can be made regarding
its true affinities. It does not appear to be an Oxyrrhis.

Oxyrrhis marina Dujardin
Text figure R, 3

Oxyrrhis marina Dujardin (1841), p. 347, pl. 5, fig. 4.

O. marina, Diesing (1850), p. 57; (1865), p. 79.

Glyphidium marinum Fresenius (1865), pp. 83, 84, figs. 4-10.
G. marinum, Cohn (1866), pp. 295, 296, pl. 15, figs. 36, 37.
Oxyrrhis marina, Cienkowsky (1881), pp. 1380-171, figs. 1-3.

118 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

O. marina, Saville-Kent (1880-82), pp. 427, 428, pl. 24, figs. 53, 61.

O. marina, Gruber (184), p. 417.

O. marina, Blochmann (1884), pp. 46-49, pl. 2, figs. 14-21.

O. marina, Biitschli (1885a), p. 845, pl. 45, fig. 12; (1885b), pp. 558, 559, figs. 1, 2.

O. marina, Stepanoff (1885).

O. marina, Gourret and Roeser (1886), pp. 448, 522-524, pl. 34, figs. 11-19.

O. marina, Delage and Hérouard (1896), pp. 306, 314, 336, fiz. 533.

O. marina, Entz (1897), pp. 177, 181; (1901), pp. 96, 98.

O. marina, Senn (1900), p. 187, fig. 93; (1909), pp. 85-87; (1911), pp. 605-672, pl. 30,
text figs. 1-7.

O. marina, Scherffel (1900), p. 3.

O. marina, Massart (1901), p. 81.

O. marina, Lang (1901), p. 171; (1913), p. 231, fig. 232.

O. marina, Keysselitz (1908), pp. 334-339, pl. 19.

O. [marina], Willey and Hickson (1909), p. 184, fig. 102.

O. marina, Giinther (1911), p. 9.

O. marina, Doflein (1911), p. 529.

O. marina, Minchin (1912), p. 278, fig. 123.

O. marina, Griessmann (1913), pp. 3, 14.

O. marina, Lebour (1917a@), p. 154; (1917b), pp. 198, 199.

Dracnosis.—Body elongate oval, asymmetrical posteriorly; girdle imperfect
on right side, without a postmargin; flagella midventral; stout tentacle-like
lobe pendant between the two flagella, dividing the broad undeveloped ventral
sulcus; colorless; length, 10-374. Marine.

Description.—The body is elongate oval, widest at the girdle, its length 2.25 transdiameters,
and 2.6-3.2 dorsoventral diameter. The epicone is ovoidal, apex broadly rounded, over twice
the size of the hypocone; its length at the origin of the transverse flagellum is about 0.5 total
length, and at the left margin of the body about 0.75 total length. The hypocone is about 0.5-0.7
the diameter of the epicone and 0.5—0.25 the total length in length, tapering conical, displaced
to the left, deficient on the right. It is broadly and deeply excavated ventrally. The antapex
is bluntly rounded.

The girdle is peeularly modified. It is incomplete, making about 0.75 of a cireuit, fading
out on the right side of the body. The anterior lip is a sharply overhanging shelf, but the
posterior is lacking. Beginning in the midventral region, at the proximal end of the transverse
flagellum the girdle drops obliquely posteriorly to the left margin of the body about half way
to the antapex and continues thence transversely across the dorsal surface to the right side, where
it vanishes. The suleus is a broad excavation spreading over a considerable part of the ventral
surface of the hypocone. It is divided in the median line by the pendant, tentacle-like lobe which
separates two flagellar pores. This lobe is pear-shaped in outline, is half as long as the hypocone,
and is attached by its stem between the two flagella to the anterior lip of the girdle and by its
dorsal face to the hypocone. It may be extended as a more slender tentacle. It does not appear
to be a modified flagellum.

The longitudinal fiagellum originates on the right side of this lobe and the transverse one on
the left. The former may extend directly posteriorly or it may wrap itself around the lobe,
turning first anteriorly to the pore of the transverse flagellum and projecting posteriorly from
that region, according to Senn (1911). There is a blepharoplast at the base of each flagellum.
The transverse flagellum is about as long as the girdle, and is thrown into short undulations or a
close spiral coil, but is not figured as a ribbon by Senn (1911), in which form it occurs in other
dinoflagellates.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 119

The cytoplasm is colorless, with a peripheral layer of stout rhabdosomes, 0.3 transdiameter in
length. _The nucleus lies in the lower epicone. It is an ellipsoid, 0.66 transdiameter in length
and 0.50 in width, with about twelve moniliform chromatin threads on one face and a central
nucleolus.

Binary fission is slightly oblique and the daughter cells form in chains as in other
dinoflagellates.

Dimensions.—Length, 22-32», rarely 10-37; transdiameter, 15-20.

OccURRENCE.—This species was originally described by Dujardin (1841) in
salt water from the Mediterranean containing Ulva which had stood for some
months. In fact most of the studies of this interesting and perplexing flagellate
have been made from aquarium cultures. The only reports of the occurrence
of the species from marine waters are those of Saville-Kent (1880-82), who
found it in water samples from St. Heliers, Jersey, as well as in aquarium
cultures from this region; of Cienkowsky (1881), who reported it from the
White Sea; of Gruber (1884), who listed it from the harbor at Genoa, Italy;
of Gourret and Roeser (1886), who found it sparingly in harbor water at
Marseilles, France; of Massart, who collected it on brackish-water pools at
Palingbrug. near Nieuport, Belgium; of Entz (1897), who discovered it in col-
lections from brackish-water pools on a coral islet at Tengeriek, New Guinea;
of Lohmann (1909), who records it from the harbor waters at Kiel; and Lebour
(1917a, b), who found it sparingly in water samples at Plymouth, England.

On the other hand, it has been reported in great abundance in sea water
aquaria at Frankfort, Germany, by Fresenius, who called it Glyphidiwm
marinum. It was again found by Cohn (1865), who gave it this same name, in
a window aquarium at Breslau supplied from Helgoland. Blochmann’s (1884)
studies were made on material from the Heidelberg Aquarium; Senn (1909)
at Basel, Switzerland, noted it in great abundance in a culture from Naples
containing Bryopsis, kept at 20° to 25° and not fouled by bacteria, flagellates,
and ciliates. Griessmann noted its occurrence in aquaria supplied with sea
water and seaweeds from Roscoff, Helgoland, and Villefranche. Lebour
(1917)) reports it in great abundance in laboratory plankton cultures, especially
with the diatom Nitzschia closterium.

Of special interest is its occurrence in continental salt lakes of the province
of Kharkoff, Russia, reported by Stepanoff (1885).

SynonyMy.—There is no doubt that the organism described by Fresenius
(1865) as Glyphidium marinum, and later reported by Cohn (1886), is Dujar-
din’s Oxyrrhis marina. The peculiar location of the flagella and their posterior
position in locomotion, coupled with Dujardin’s (1841) noncommittal horizontal
orientation of his figures, misled these earlier investigators in their conclusions.

CHAPTER X

GYMNODINIIDAE: HEMIDINIUM, AMPHIDINIUM

Family 2. GYMNODINTIIDAE Kofoid

Gymnodinida Bergh (18816), p. 274. Subfamily.
Gymnodinieae, Sehiitt (1896), p. 3.

Amphidinieae Schénichen and Kalberlah (1900), p. 229.
Gymnodinidae Kofoid (1907a), p. 164; (19076), p. 293.
Gymnodiniidae, Poche (1913), p. 162.

Kyrtodiniaceae Schilling (1913), p. 12.

DraGcnosts.—Gymnodinioidae with girdle varying in length from 0.5 to 4
turns around the body; suleus extending from near apex to near antapex;
ocellus and tentacle lacking; pusules usually present; plasma may contain
chromatophores, colored pigment or be itself highly colored. Length, 11 to
221”, They are found in both fresh and salt water, are eupelagic, neritic or
littoral, and occur in arctic, cool and warm temperate and tropical waters.

DescripTioN.—The members of this family show a progressive differentiation of the body as
shown in the length of the girdle and the torsion of the body resulting therefrom. Both suleus
and girdle are weil developed, the latter varying in length from 0.5 to 4 turns around the body,
with a corresponding lengthening of the suleus. With the increasing torsion of the body the
length of the suleus increases mainly in the intereingular area, rarely showing apical or antapical
loops. The nucleus generally lies near the center of the body and may or may not have a
perinuclear membrane. Its chromatin contents are always arranged in characteristic long, monili-
form chromatin strands. Pusules are usually present, opening anteriorly into the anterior and
posteriorly into the posterior flagellar pore, or both may be connected by a slender canal, forming
a complete channel between the two openings.

The plasma may be highly colored and frequently contains colored pigment. Chromatophores
are found quite generally in the fresh-water forms, more rarely in the marine species, occurring
in Amphidinium, Gymnodinium, and Gyrodiniwm. Nutrition is both holozoie and holophytie,
and apparently both phases may be assumed in the same species; individuals occasionally met
exhibited both chromatophores and food bodies in the cytoplasm at the same time.

The cytoplasm may show a differentiation into ectoplasm and endoplasm or the former may
consist only of a thin periplast. Longitudinal striae on the surface of the body are frequent.
Cyst formation is frequent, either as the result of the ingestion of large food bodies or as division
cysts. It is secreted by the body as a closely adherent membrane, which becomes distended by
gradually accumulated fluid between itself and the body.

This family contains 6 genera: Hemidinium, with 2 species; Amphidinium, 22; Gymnodinium,
76; Gyrodinium, 47; Cochlodinium, 29; and Torodinium, 2, giving a total of 178 species. They
form one of the most closely intergrading groups in the Dinoflagellata, with clearly established
lines of relationship and evolutionary development.

We add to this family two new genera, Gyrodinitwm and Torodiniwm, and 92 new species
distributed among the genera as follows: To Amphidinium, 12 new species; to Gymnodinium,
36; to Gyrodiniwm, 21; to Cochlodinium, 21; and to Torodinium, 1.

[120]

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 121

Key TO THE GENERA OF THE Famity Gymnodiniidae

Gurr lego fea OF 5% Gtemne OMn gears cette teen een SE ST on SE) LSS Ie Ba Hemidinium Stein
Girdle anterior, epicone relatively minute ___........-.--.------------- Amphidinium Clap. and Lach.
Girdle submedian, displaced less than 0.2 total length of body —.......... Gymnodinium Stein

Girdle posterior, without displacement, sulcus with long apical loop_....Torodinium gen. noy.

CS ore

Girdle displaced 0.2 or more of total length of body with torsion of 1 to less than 1.5 turns...
Js Seb je Ace EE SEE eee Gyrodinium nom. sp. nov.

6aGirdletwathitorsion! ofl: or amOre) GUMS) esses eee eee eee Cochlodinium Schiitt

HEMIDINIUM Stein
Text figure R, 4

Hemidinium Stein (1888), pp. 91, 97, pl. 2, figs. 23-26.

Hemidiniwm, Eyferth (1879), p. 19.

Hemidinium, Saville-Kent (1880-82), pp. 210, 440, 442.

Hemidinium, Bergh (1882), p. 694; (1884), pp. 385, 387.

Hemidinium, Biitschli (1885), pp. 1008, 1016, pl. 51, fig. 3.

Hemidinium, Delage and Hérouard (1896), p. 384, fig. 667.

Hemidinium, Schiitt (1896), p. 4, fig. 3.

Hemidinium, Mez (1898), p. 217, pl. 6, fig. 286.

Hemidinium, Schilling (1891a), pp. 274, 275, pl. 8, figs. 23-25, pl. 10, fig. 8.

Hemidinium, Lemmermann (1900), p. 115; (1901), p. 358; (1902), p. 260; (1910), pp.
580, 617, 618, figs. 14-18.

Hemidinium, Schénichen and Kalberlah (1900), p. 230, pl. 8, fig. 1; (1909), p. 251, pl. 8,
fig. 1.

Hemidinium, Willey anl Hickson (1901), p. 184, fig. 10.

Hemidinium, Paulsen (1908), pp. 94, 95, fig. 127.

Hemidinium, Conn (1905), p. 39.

Hemidinium, Cavers (1913), p. 183, fig. 9.

DraGnosts.—Gymnodiniidae with incomplete girdle of 0.5 turn; 2 species,
from fresh water.

DEsScRIPTION.—The body is asymmetrically ellipsoidal to ellipsoidal in form; girdle median
to premedian, incomplete, forming less than 0.5 turn of a descending left spiral; sulcus confined
to the hypocone. The nucleus is ellipsoidal to spheroidal with chromatin granules. The echro-

matophores are yellowish to brownish. No stigma. Small species, 24-33» long. Fresh water,
Europe. Two species.

HistoricaL Discussion.—This genus was described by Stein (1883) and
included but a single species, H. nasutum Stein, the type species of the genus.
Tt has no other characteristics of a primitive nature except holophytie nutri-
tion. Levander later (1900a) added a second species to the genus, H. ochraceum,
also from fresh water.

122 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

CoMParIsons.—This genus has been generally accepted and widely used as
a primitive representative of the Dinoflagellata because of its partially devel-
oped girdle. In view of the fact that it is a fresh-water genus, without, as yet,
any representative on the sea, it may be that the imperfect condition of the
girdle is really a degenerate rather than a primitive one. It has a descending
spiral, though incomplete, girdle, and in this particular is nearer Gyrodinium
than to Gymnodinium. Klebs (1883) states that Hemidinium has a cell mem-
brane which swells in sulphuric acid and stains yellow in iodine, is finely gran-
ular and sometimes striate. It appears, however, to be no more than the pellicle
of the unarmored dinoflagellates. The matter should be more fully investigated.
The genus is tentatively included in the Gymnodiniidae.

Key To THE SPECIES OF Hemidinium
Epicone and hypocone subequal, proximal end of girdle deflected posteriorly........ nasutum Stein

Epicone much smaller than the hypocone, proximal end of girdle deflected anteriorly —...........
a a ea Pe eRe pr Se err ochraceum Levander

Hemidinium nasutum Stein
Text figure R, 4

Hemidinium nasutum Stein (1883), pp. 91, 97, pl. 2, figs. 23-26.

. nasutum, Eyferth (1879), p. 19.

. nasutum, Saville-Kent (1880-82), p. 442.

. nasutum, Klebs (1883), pp. 348, 351, pl. 2, fig. 27; (1884), p. 739.

. nasutum, Daday (1884), p. 10.

. nasutum, Biitschli (1885a), p. 559, fig. 1; (18856), 1008, 1016, pl. 51, fig. 3.

. nasutum, Dalla Torre (1885), p. 272.

. nasutum, Schilling (1891a), pp. 248, 248, 274, 275, pl. 8, figs. 23-25, pl. 10, fig. 8.

. nasutum, Franeé (1893), p. 139.

. nasutum, Levander (1894), p. 48; (1900a), pp. 58, 64; (1901), p. 6.

nasutum, Delage and Hérouard (1896), p. 384, fig. 667.

. nasutum, Entz (1896), p. 22; (1897), pp. xxxi, 52; (1902), p. 126; (1904), pp. 8, 11.
. nasutum, Sehiitt (1896), p. 4, fig. 3.

. nasutum, Butsechinsky (1897), p. 195.

. nasutum, Ludwig (1898), p. 298.

. nasutum, Mez (1898), p. 217, pl. 6, fig. 286.

. nasutum, Schénichen and Kalberlah (1900), p. 230, pl. 8, fig. 1; (1909), p. 251, pl. 8,
fig. 1.

. nasutum, Lemmermann (1900), p. 115; (1901), p. 858; (1902), p. 260; (1906), p. 419;
(1910), pp. 617, 618, 580, figs. 14-18.

. nasutum, Zacharias (1903), pp. 237, 244.

H, nasutum, Paulsen (1908), p. 94, fig. 127.

H. nasutum, Kleiber (1911), p. 14.

H. nasutum, Senn (1911), p. 64, fig. 6.

H. nasutum, Cavers (1913), p. 182, fig. 9.

H. nasutum, West (1916), p. 75.

yes

se)

S RRP ee

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 123

DraGnosis.—Body asymmetrically ellipsoidal, flattened on three sides, rotund
on the left; its length 1.75 transdiameters; girdle a descending left spiral of
0.5 turn, its anterior lip protuberant; sulcus reaching postmargin; chromato-
phores yellow to brown. Length, 24-28". Fresh-water ponds and pools in clear
water. Europe.

DEscripTION.—The body is noticeably asymmetrically ellipsoidal with flattened ventral, right,
and dorsal faces, but rotund left face interrupted by the protuberant anterior lip of the girdle.
Its length is 1.5 to 1.65 transdiameters at the widest part, which is at the base of the epicone. The
epicone and hypocone are subequal, both with asymmetrical, subhemispheroidal apices, the antapex
sometimes exhibiting a shallow sulcal notch.

The girdle is incomplete, making 0.5 turn of an evenly descending left spiral with a total
displacement of 0.33 of the length of the body. Its anterior lip on the left margin is strongly
protuberant, hence the specific name. The posterior lip is more rounded than the anterior. It
fades out distally at the middorsal line. The sulcus is confined to the hypocone and extends as
a straight furrow from the girdle to the postmargin in which it may form a shallow notch. The
two flagella originate near the junction of girdle and suleus in close proximity.

The nucleus is a small ellipsoid in the left posterior part of the hypocone. Its axes are 0.30
and 0.25 transdiameter in length respectively. Its membrane appears to be double-contoured, and
typical chromatin threads have not, as yet, been figured in it.

The peripheral cytoplasm is filled with elliptical reddish brown chromatophores and reddish
brown oil drops as stated by Schilling (1913) to be present in the spherical cyst. Klebs
(1883) states that this species has a distinct, separable cell wall which swells in soda and sulphuric
acid, stains yellow in iodine and brown in chloride of zine. Schilling (1913) states that it is
composed of cellulose, though Klebs had distinctly noted that it does not stain blue on test for
cellulose. Further investigation is needed to determine the presence of this so-called cell wall
and to determine its nature as compared with the pellicle of the Gymnodinioidae with which we
here include it.

DIMENSIONS.
20n.

OccurRRENCE.—Originally described by Stein (1883) from Prague, Austria,
and later reported by Klebs (1883), Schilling (1891, 1913), Levander (1894,
1900a, 1901), Francé (1893), and Dalle Torre (1885), from continental fresh
waters in Europe from the Tyrol to Finland. Schilling (1913) states that it
is rather common in shaded fresh-water pools, ponds, ditches and swamps in
clear water. Butschinsky (1897) reports it as rare in a salt lake near Odessa,
Russia, with a concentration of 5 per cent. Since he also reports Oxyrrhis
marinum (as Glyphidium marinum) from the same water, it seems improbable
that he has confused the two species. There is no other record of the species
from salt or brackish water. Its occurrence therein requires verification. It
has not been reported from the Americas.

ComParIsons.—It appears to be quite distinct from H. ochraceum of Ley-
ander (1900a), who found them both in temporary rain-water pools on rocks
in Finland. Both have the thin pellicle, but differ in the position of the girdle,
which in this species is more nearly equatorial, as in Gymnodinium, while in
G. ochraceum it is anterior, as in Amphidinium.

Length, 24-28; transdiameter, 16-17; nucleus, 7-8; cyst,

‘

124 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Hemidinium ochraceum Levander

Hemidinium ochraceus Levander (1900a), pp. 58, 61, 103, 104, fig. 2.
H. ochraceum, Lemmermann (1909), pp. 580, 618, figs. 14, 15.

Dracnosts.—Body broadly ellipsoidal, its length 1.3 transdiameters; epicone
about 0.25 of the hypocone; girdle with 0.5 circuit, steeply descending on dorsal
face, sulcus not reaching postmargin; vellowish green to reddish brown; length,
23-334, Fresh-water pools, Finland.

DeEscrIPTION.—This is asymmetrically and broadly ellipsoidal, widest at the middle, its length
1.3 transdiameters, slightly flattened dorsoventrally. The epicone, measured at the proximal end
of the girdle, is 0.25 of the total length. It is not separable from the hypocone on the right side.
The apex is flattened hemispherical in shape. The hypocone is three times as long as the epicone,
elongate hemispheroidal in shape with no suleal notch in the postmargin.

The girdle is incomplete, making a trifle less than 0.5 turn. From the proximal end it ascends
at an angle of 20° above the transverse plane to the left margin, where it turns abruptly poster-
lorly at an angle of 70° below the transverse plane, terminating In a narrow trough to the right
of the middorsal line a little below the equator. It has a net displacement of 0.35 and a total
displacement of 0.50 length of the body. The anterior lip is less protuberant than in H. nasutum,
and the posterior one is broadly rounded. The suleus proceeds posteriorly from its junction with
the girdle about half way to the postmargin. Levander’s (1900a@) interpretation of the girdle
and sulcus as a single furrow misconstrues the suleus. The two flagella arise near each other at
the junction of girdle and suleus. Lemmermann’s (1909) copy of Levander’s figure is in error
in uniting the two flagella at their bases.

The nucleus is spheroidal, 0.33 transdiameter wide, and filled with chromatin grains. It is
located in the posterior part of the hypocone. The color is reddish brown anteriorly and yellowish
green elsewhere. Chromatophores not designated but presumably present. Cysts yellowish green
with reddish brown center, spheroidal.

Dimenstons.—Length, 26-33; transdiameter, 23-264. Cysts, 31z.

OcCcURRENCE.— Described by Levander (1900@) as abundant in shallow rain-
water pools on rocks on the Skaren Islands, Finland, in association with H.
nasutum Stein.

Comparisons.—Levander (1900a) notes the presence on this species of a
thin ‘‘shell.”’ If this is not merely a heavy pellicle, but a shell of the type found
in Glenodinium, this species, perhaps with H. nasutum, should be transferred
to the thecate Peridinioidae. In any event, this species affords, in this struc-
tural particular, an intermediate condition which tends to bridge over the gap
between the athecate Gymnodinioidae and the thecate Peridinioidae.

AMPHIDINIUM Claparéde and Lachmann
Text figure U

Amphidinium Claparéde and Lachmann (1858-61), p. 410, pl. 20, figs. 9-12.
Amphidiniwm, Saville-Kent (1880-82), p. 461, pl. 25, figs. 44-46.
Amphidinium, Bergh (1882), pp. 693-695.

Amphidinium, Biitschli (1885), p. 1011, pl. 54, figs. 6, 7.

Amphidinium, Schiitt (1896), p. 4, fig. 4.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 12!

On

Amphidinium, Delage and Hérouard (1896), p. 386, fig. 678.

Amphidinium, Schonichen and Kalberlah (1900), p. 230, pl. 8, fig. 2; (1909), p. 251, pl.
8, fig. 2.

Amphidinium, Calkins (1902), p. 482, fig. 27.

Amphidinium, Paulsen (1908), p. 95.

Amphidinium, Lohmann (1909), p. 223, figs. 19-21, 26.

Amphidinium, Lemmermann (1910), pp. 580, 615, figs. 1-8.

Amphidinium, Schilling (1913), p. 138, fig. 9.

Dracnosis.—Body usually compressed; girdle placed far anteriorly, with
little or no displacement; sulcus extending from girdle, rarely from apex, to
antapex without torsion; epicone relatively minute. Nucleus generally poster-
iorly or centrally located. Pusules opening anteriorly into the anterior flagellar
pore, posteriorly into the posterior pore, or both may be fused into one. No
nematocysts present. Plasma colorless with or without chromatophores or
colored without chromatophores. Surface may show fine striae, furrows, or
ridges may be smooth. Encystment in thin-walled membrane frequent. Nutri-
tion holophytic or holozoic. Length, 12 to 110#. Marine, fresh and brackish
waters, eupelagic and neritic forms; warm or cold temperate seas; 22 species
described.

ORGANOLOGY

The genus Amphidinium is, in many respects, the most simply organized of
the Gymnodiniidae, yet it anticipates the conditions found in the more highly
evolved groups even of the Dinophysidae. The body is without torsion and
differs from Gymnodinium mainly in the position of the girdle, the greater
frequency of a dorsoventral compression of the body and the more frequent
possession of chromatophores.

The girdle is placed far anteriorly, at least on the dorsal side, and either
forms a circle transversely around the body or turns posteriorly on the ventral
side. One species only, A. scisswm (fig. U, 1), has a displacement of the girdle
similar to that found in Gymnodinium and Gyrodinium. In the other species
the ends of the girdle meet without displacement, the apparent exception being
A. sulcatum (fig. U, 10). In this species the girdle becomes contracted on the
right side, while the left side is expanded, forming an apparent displacement
of the proximal borders but not of the distal borders of the girdle (fig. U, 26).

The anterior position of the girdle makes the relative sizes of the epicone and
hypocone one of the most striking features of the genus. The divergent form,
A. asymmetricum (fig. U, 5), shows the greatest deviation from the type in this
respect, and foreshadows the conditions in Gymnodinium. The position of the
girdle dorsad, however, is farther anterior than is the case in any species of that
genus,

The larger group of species (subgenus Amphidinium sensu strictu) shows
a strong dorsoventral compression of the body with one exception, A. sulcatum,

126 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Fig. U. Amphidinium. 1, A. scisswm sp. noy. 2. A. herdmani nom. sp. nov. After Herdmann (1911, pl. 8,
fig. 5). 3. A. truncatum sp. nov. 4. 4. dentatum sp. nov. 5. A. asymmetricum sp. noy. 6. A. corpulentum sp. nov.
7. A. longum. Lohm. After Lohmann (1908, pl. 17, fig. 15). A. aculeatum Schr. After Schroder (1911, fig. 1).
9. A. lanceolatum Schr. After Schréder (1911, p. 650, fig. 15). 10. A. sulcatum Kofoid. After Kofoid (1907,
pl. 22, fig. 1). Lateral view. 11. A. fastigium sp. nov. Lateral view. 12. 4. cucurbita sp. nov. 13. A. corpu-
lentum sp. nov.. X 600. Conjugation? 14. A. klebsi nom. sp. nov. After Klebs (1884, pl. 10, fig. 12). 15. A.
lacustre Stein. After Stein (1883, pl. 17, fig. 21). 16. 4A. turbo sp. nov. 17. A. aculeatum Daday. After Daday
(1888, pl. 3, fig. 10). 18. A. crassum Lohm. After Lohmann (1908, pl. 17, fig. 15). 19. A. ovoidewm Lemm.
After Lemmermann (1896, fig. 1). 20. A. globosum Schr. After Schroder (1911, fig. 16). 21. A. emarginatum
(Clap. and Lach.) Diesing. After Claparéde and Lachmann (1853, pl. 20, fig. 11). 22. A. rotundatum Lohm.
After Lohmann (1908, pl. 17, fig. 9). 23. A. discoidalis (Clap. and Lach.). After Claparéde and Lachmann
(1858, pl. 20, fig. 12). 24. A. pacificum sp. nov. 25. A. operculatum Clap. and Lach. After Calkins (1902, fig.
27). 26. A. sulcatum Kofoid. After Kofoid (1907a, pl. 22, fig. 2). 27. A..vasculum sp. nov. 28. A. steint
(Stein) Lemm. After Stein (1883, pl. 17, fig. 9). 29. 4. galbanum sp. nov. 30. A. cucurbitella sp. nov. X 500,
except where otherwise stated.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA _ 127

which is strongly compressed laterally (fig. U, 10, 26). This is a condition rare
in Gymnodinium, being met with there mainly in a few fresh-water forms.
Correlated with this form of body is the presence of definite chromatophores.
These are lacking in one species only, A. scisswm, in which the green color is
diffused through the cytoplasm. The chromatophores show three distinct types,
which may possibly be only phases related to different stages of metabolism or

of the life history. The most common form of chromatophore is that found in
A. corpulentum, A. dentatum, A. ovoideum, and A. truncatum (figs. U, 6, 4, 19,

3). These structures are disklike bodies located in the peripheral laver of the
cytoplasm, and more or less irregular in shape. They are green in A. dentatum
and A. truncatum, yellow ochre in A. corpulentum, and brownish in A. ovoideum.
Another phase of these extremely labile organelles may be seen in the smaller
green bodies in the peripheral zone of A. scisswm, which may be the remains of
larger green chromatophores from which the color has become diffused through
the cytoplasm (pl. 2, fig. 22).

Another example of the same type is found in the subgenus Rotundiniwm
in A. pacificum (pl. 2, fig. 18), in which the chromatophores are pyrite yellow.

The second type of chromatophores is shown in A. operculatum, with its
long, bandlike chromatophores radiating from a common center near the middle
of the body (fig. U, 25). These are also found in A. herdmani and A. steint
(figs. U, 2, 28). A slightly different arrangement obtains in A. klebsi, where
the chromatophores radiate from a common center located at the posterior end
of the body (fig. U, 14). These are brownish (yellow ochre?) in A. herdmani,
A. steini, and A. klebsi (7).

The third type of chromatophore is found in the subgenus Rotundinium in
A. asymmetricum (pl. 1, fig. 1). The single yellow ochre chromatophore is large,
filling almost the entire body, with ramifying, pseudopodia-like projections.

Tn the subgenus Rotundinium the body has a robust habit, circular or nearly
so in cross-section. With this is correlated, in the larger species, an increasing
complexity of cytoplasmic structure, culminating in A. cucurbita (pl. 1, fig. 9).
This species resembles, in the structural details of its cytoplasm, the subgenus
Pachydinium in Gymnodinium (pl. 3). With four exceptions this group shows
a relative absence of chromatophores, the exceptions being A. rotundatum (fig.
U, 22). with its peripheral, leaflike yellow chromatophores, A. asymmetricum
(fig. U, 5), with single, large, yellow ochre chromatophore, A. lacustre (fig.
U, 15), with peripheral, circular, brown chromatophores, A. galbanum (fig. U,
29), with peripheral, leaflike chromatophores, and A. pacificum (fig. U, 24),
with pyrite yellow chromatophores near the surface.

In A. cucurbita, A. cucurbitella, A. fastigium, and A. vasculum the color is
diffused throughout the cytoplasm, while A. turbo, A. longum, and A. crassum
are colorless.

The suleus exhibits various degrees of development in Amphidinium. In
A. turbo (fig. U, 16) it is a very short, V-shaped indentation of the anterior

128 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

border of the hypocone. In A. lacustre (fig. U, 15) the V-shape trough extends
as a narrow line to the antapex. In four species only does it invade the epicone.
In A. corpulentum, A. vasculum, A. scissum, and A. sulcatum (figs. U, 6, 27, 1,
26) it reaches near to and, in the last species, slightly beyond the apex. Its
borders posterior to the girdle are frequently extended in flaplike projections.
These are exaggerated on the left side in A. asymmetricum (fig. U, 5). In
A. sulcatum (figs. U, 10, 26) the right border is enlarged anteriorly, the left
border posteriorly. The antapex may be excavated by the sulcal notch, as in
A. sulcatum and A. asymmetricum or smoothly rounded as in A. operculatum
(figs. U, 26, 5, 25).

Amphidinium possesses the type of pusule found throughout the Gymnodi-
niidae. One or two may be present, either opening anteriorly into the anterior
flagellar pore or posteriorly into the posterior pore. In A. truncatum these
are merged into one large, irregularly shaped pusule opening into both pores.

The nucleus of Amphidinium usually has distinct, moniliform chromatin
threads and is without a perinuclear membrane. It is generally found near
the center or in the posterior part of the body.

The genus Amphidinium shows a narrow range of coloring. The predomi-
nant color is green, varying to greenish yellow, and yellow shading to orange
in A. cucurbita (pl. 1, fig. 9), and to yellow ochre in the other species. It is
probable that the brownish color given for many of the earlier described forms
is vellow ochre, a common color throughout the Dinoflagellata.

Striae or other surface markings are not so common in Amphidinium as
in Gymnodinium and Gyrodinium. Three species, A. asymmetricum, A. den-
tatum, and A. scissum (fig. U, 5, 4, 1), show the fine surface striae common to
the latter genera. The surface in A. cucurbitella (fig. U, 30) and A. cucurbita
(fig. W,.3) is marked by deep furrows with very fine striations between, quite
unlike anything found elsewhere. In A. fastigiwm (fig. U, 11) it is marked by
a few distinct ridges and in A. galbanum (fig. U, 29) by furrows. The surface
markings of A. klebsi are too indefinite in Kleb’s figure (1885) to be classified.

Nutrition in the species of this genus is both holophytic and holozoic. When
chromatophores are present it is presumably holophytic, yet not invariably so.
In A. steini chromatophores are usually present, yet undoubted evidence of the
ingestion of foreign bodies is also given by Stein (1883, pl. 17, figs. 14-16). The
chromatophores in these figures are very small. Among our species, A. scisswm
possesses what may be the remains of small chromatophores and also shows the
presence of two large food masses. The other forms without chromatophores
in most cases show the presence of food bodies within the cytoplasm.

Cyst formation is common throughout the group. Binary fission may take
place within a cyst or in the freely swimming forms.

DIsTRIBUTION.—Species of Amphidinium have been described mainly from
the warm and cool temperate waters. None have been found thus far in tropical
seas and only one from the colder northern waters, Mielck (1914) reporting

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 129

the presence of A. rotundatwm in the White and Barents seas. A number of
species have been recorded from the Baltic Sea and off the coast of Norway
and Sweden. Of these Lohmann (1908) found A. longum, A. crassum, and
A. rotundatum at Kiel, Germany ; Lemmermann (1896)) described A. ovoideum
in brackish waters near Plon, Germany; and Stein (1883) figures 4. steini from
Wismar, Germany. A. operculatum has been recorded by Claparéde and Lach-
mann (1858-61) from the southwest coast of Norway, by Cleve (1884) from
the west coast of Sweden, and by Calkins (1902) from the Atlantic at Woods
Hole, Mass.

The only species recorded from the Mediterranean are A. klebsi by Klebs
(1884) from the Bay of Naples and A. Janceolatum by Schroder (1911) from
the Adriatic. The only species thus far reported from the Pacific is A. sulcatwm
by Kofoid (1907a) off San Diego.

To this single record for the Pacific we add in this paper from the plankton
and sandy beach off La Jolla, California, the following twelve new species:
A. asymmetricum, A. corpulentum, A. cucurbitella, A. cucurbita, A. dentatum,
A. fastigium, A. pacificum, A. galbanum, A. scissum, A. truncatum, A. turbo,
and A. vasculum.

A single species, A. Jacustre, has been described from fresh-water pools near
Prague, Austria, by Stein (1883). Schilling (1913) records the finding of this
species in brackish waters in Hungary by Daday.

Amphidiniwm is chiefly a littoral or shore form, but a few species have been
described from deeper waters. Six of these are from the Pacific and are the
largest species in the genus. A. cucurbita and A. cucurbitella were found only
at 1.5 to 6 miles offshore, from a depth of 80 meters, and A. sulcatum in a haul
from 165 meters 10.5 miles offshore. A. operculatum has been recorded both
from deep waters and from a sandy beach, the latter observation made by
Spengel at Norderney, Denmark, and recorded by Bergh (1882). Herdman
(1911, 1912) found A. herdmani with several unknown species of Amphidiniwm
in vast quantities on the sandy beach at Port Erin, Isle of Man. The species
found on the sandy beach at La Jolla, on the Pacific coast, are A. scisswm, A.
asymmetricum, A. corpulentum, A. dentatum, and A. truncatum.

The seasonal record of the appearance of the species of this genus is only
fragmentary. Many of them are present throughout the year. Calkins (1902)
found A. operculatum common at Woods Hole, Mass., from July to September ;
Bergh (1882) records its presence in enormous masses on the beach at Norder-
ney, Denmark, in December and January. Lohmann (1908) found A. rotwn-
datum and A. crassum present in the Baltic Sea at Kiel throughout the year.
The latter species Lebour (1917a) found from June to September at Plymouth
Sound, England, and A. rotundatum was recorded from the White and Barents
seas in June and July by Mielck (1914). A. klebsi was recorded by Klebs
(1884) from the Bay of Naples in the early spring months. A. herdmani was
found in vast numbers at Port Erin, Isle of Man, from April to November by
Herdman (1911-13).

130 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The species found by us on the Pacific coast were taken in July and August.
Plankton hauls have been made throughout the year, but preservative has been
immediately added to these hauls, and it is very rarely indeed that these soft,
naked forms preserve their identity after contact with the fixing fluid.

Historical Discussion

The genus Amphidinium was established by Claparéde and Lachmann
(1858-61), who figured A. operculatum and two other forms which they thought
might be varieties of the same species. These were later established by Diesing
(1866) as A. operculatum var. discoidalis and A. operculatum var. emarginata.
Their allocation, however, in this genus is doubtful, at least until they have
been found again. Stein (1883) figured as A. operculatum a form which Lem-
mermann (1900) changed to var. stevni. Klebs (1884) also figured as A. oper-
culatum what we have designated as A. klebsi, nom. sp. nov. Using the same
species name, Herdman (1911-13) figures still another form which seems to
be specifically different from the three previously described under that name.
This we have designated A. herdmani nom. sp. nov.

In 1888 Daday added to the genus A. aculeatum as a new species, a form
which has no apparent Amphidinium characteristics, if indeed it belongs in the
Dinoflagellata at all, which seems doubtful. Schroder (1911) uses the same
species name for a totally different form and one which also presents no
Amphidinium characteristics. These two forms we exclude from the genus.
Schroder, in the same monograph, adds A. globosum and A. lanceolatum. The
first of these is without Amphidinium characters and must likewise be excluded
from the genus. <A. lanceolatum we regard as an Amphidinium, but one which
needs to be redescribed.

Stein (1883) described the only fresh-water form in the genus, A. lacustre.

Lemmermann (1900) added to the genus as A. ovoidewm a form previously
deseribed by himself (1896) as Prorocentrum micans. Lohmann (1908) added
the incompletely described species A. crassum, A. longum, and A. rotundatum.
A. sulcatum was added by Kofoid (1907).

To the eight previously described species, to wit, A. crasswm Lohmann, A.
lacustre Stein, A. longum Lohmann, A. operculatum Claparéde and Lachmann
emend., A. ovoideum Lemmermann, A. rotundatwm Lohmann, A. steini (Stein),
and A. sulcatuwm Kofoid, we add twelve new species from the plankton and
beach of the Pacifie off La Jolla, California, as follows: A. asymmetricum,
A. corpulentum, A. cucurbitella, A. cucurbita, A. dentatum, A. fastigium, A.
galbanum, A. pacificum, A. scissum, A. truncatum, A. turbo, and A. vasculum,
and two more from the literature, A. herdmani nom. sp. nov. and A. klebsi nom.
sp. noy., based on Herdman’s (1911-1913) and Klebs’s (1884) figures of A.
operculatum, respectively.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 131

Subgenera of Amphidinium
Subgenus 1. Amphidinium subgen. nov.

Body compressed either dorsoventrally or laterally. Type species A. oper-
culatum Claparéde and Lachmann. This subgenus includes besides the type,
A. corpulentum sp. nov., A. dentatum sp. nov., A. herdmani nom. sp nov., A.
klebsi nom. sp. nov., A. ovoideum Lemm., A. scissum sp. nov., A. steini (Stein),
A. sulcatum Kofoid, and A. truncatum sp. nov.

Subgenus 2. Rotundinium subgen. nov.

Body not compressed, its dorsoventral and transdiameters being subequal.
Type species A. cucurbita sp. noy. This subgenus contains in addition to the
type the following species: A. asymmetricum sp. noy., A. cucurbitella sp. nov.,
A. fastigium sp. nov., A. galbanum sp. nov., A. lacustre Stein, A. pacificum
sp. nov., A. turbo sp. nov., A. vasculum sp. nov., and tentatively the following
imperfectly described species, A. crasswm Lohmann, A. longwm Lohmann, and
A. rotundatum Lohmann.

Key To THE Species or Amphidinium

1. Body compressed either dorsoventrally or laterally (subgenus Amphidinium) —....... 2
1. Body circular in cross-section or nearly so (subgenus Rotundinium) —_............--.-.----.-.-- 11
2. Epicone small, less than 0.5 transdiameter in diameter, body compressed dorsoventrally 3
2. Epicone greater than 0.5 transdiameter in diameter 6
ME Ts talc emayvalt EVO Uta S ETc 8 © mens tenemene ete ee ee ea ec Beene eee 4
SMM UITS ek Ce SL Te Ue eee eee cece ee eceeere cee me cranes carer cee tmarere™ klebsi nom. sp. nov.
4, Chromatophores minute, rounded, numerous ................----.-e--ceeceeceneceeenee ovoideum Lemm.
Ala © hiram atop Mh OTeS wl aie Ore et aes acta ee sce ce cc ce EE oe a Sea eee ea eee reece 5
HaOhromatophores ong racial ee ee sccce- cee ce seeeeeera sn cteesacecanasasaseant operculatium Clap. and Lach.
yea © WONT OP HOLES altars OUI Ye eee nee nee ae eee tee sane nee cee ee cce mec eceneeaeecweenes steini (Stein) Lemm.
Gee Body compresses lace Wally areeeese snes eee eet eer cn ees erence ees raanec nae erecrete cee ceae sulcatum Kofoid
Geabodyacompresse da dorsoyertiall ly gestae ceecerete ses ceta cece cteeenedes cnomeneneecnerenesteneeree ats aneremaareeeccenetansrcs 7
fem Suleustexten dim oMamberlorlyaitop ap ex poses ote ce setae esac cect es cae ele acces scene csneesencneaecone-cecneceeeneceaere 8
Ue Seulopnty cacclirsvaveliiare> nally? “WNDU Saeco 9
8. Chromatophores absent, surface striate scissum sp. nov.
8. Chromatophores present, no surface striae ..............-.-.-----------e-eeeeee corpulentum sp. noy.
9. Hypocone striate, minute green chromatophores ...............-.-.-.---.----.------ truncatum sp. noy.
GiEbypocone notrstmate, chromatophores! Langer 22 lscceccceeececncacencesncenwneneneseecederereneeeecorcneeseeeeccerereets 10
OM Chromatophoressereen, disk-shaped eter censccecce ase cees mesencneemnencencenennnceaeereneseesas dentatum sp. nov.
10. Chromatophores yellow, long, radiating from center -..............- herdmani nom. sp. nov.
Newer eee CLES a OC luni oO funlNUie ON 9b igensrenrecre cnnerestetecceenenerenteternenecrecehennstercananannerarseaeravanrenesnenareversane 12
MMe Grivel De CLES AM OLNO Mel) Oper liny LOM Pky eseetsseceeetes cones encsens ceseconeserncterereconmarerereatctaresescarctewerssteverneetene 16

132 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

12..-Plasma: yellow, Jeng th® over OO pigs ees ee 13
12. Plasma colorless or greenish yellow, length less than 100p —..-.--.--.---2-.------cece-eeeeceeeeeeeee ee 14
13> Surface with furrows andsfine striae ese ea cucurbita sp. nov.
LBs (Surbarce wa thal ew rel ees ssa ee ee EE fastigium sp. nov.
14S Hetoplasm dicks colors y,e lo yy esses vasculum sp. nov.
145 ‘Periplasts than 2.292.525 ace 8 a Se ae ee Re ee 15
15: Surftaceswith longitudimalturrows se cucurbitella sp. nov.
5s, INO EUINT OWS! oecef aces cee eee ele ee pacificum sp. nov.
LG. GrengthoverdO je. —-.2c- 22 o2cccccccs ck 2eccecne5c5 se seo eee es aero ee 17
WG., Tuemeth less thera SO jo. se wna nes 18
17. Body asymmetrical, one leaflike chromatophore, surface finely striate -..................-------------
Pelee DE eth bu AP ADO DIE 5 Oh, ee asymmetricum sp. nov.
17. Symmetrical, many elliptical chromatophores, coarsely striate galbanum sp. noy.
18. Whencth Tess itham 125) transect ers yeas cee eee eee ee ee 19
18. Gength over’ 1:5 transdtame ters ioe ses eee ee a re ear ee 21
19. Hypoecone subeonieal, chromatophores bright yellow -............-.....-.-- rotundatum Lohmann
119! ypoconesubspheroid al 222 els es ee ee ee 20
20:) Marine: colorless: :23 2) 2 0i TS ee ee eee ee eee turbo sp. noy.
20), Hiresh\ water browm ‘chromatophores | secs ee oee renee lacustre Stein
Zi Bodyastouts Lene thei! Getranscl aim eters eee eee ae eaten crassum Lohmann
21. Body elongated, length over 2 transdiameters ____.._........------------------0--0---- longum Lohmann

Amphidinium aculeatum Daday and
Amphidinium aculeatum Schréider
Text figures U, 8, 17

Amphidinium aculeatuwm Daday (1888), p. 104, pl. 3, fig. 10.

A. aculeatum Schréder (1900), p. 13; (1911), pp. 616, 650, fig. 14, as a new species.
A. aculeatum, Lemmermann (1901a), p. 358.

A. aculeatum, Kofoid (1907), p. 301.

A. aculeatum, Herdman (19116), p. 72; (1911c), p. 39.

SynonyMy.—Under this name Daday (1888) figured (our text fig. U, 17)
an organism from the Gulf of Naples which has no apparent affinities with the
genus Amphidinium. It has no girdle and is covered with a ‘‘ Panzer,’’ or coat
of mail, thickly beset with spines. Whatever its affinities may be, they must be
looked for outside the genus Amphidinium. Schroder (1900) accepts Daday’s
species, yet in a later memoir (1911) he figures another organism (our text fig.
U, 8), from the Adriatic Sea, as ““Amphidinium aculeatum noy. spec.’’ which
is unlike Daday’s form and at the same time presents no Amphidinium char-
acteristics. Its girdle is slightly posterior to the median plane, making the
epicone and hypocone subequal. These characters alone would suffice to throw
it outside the genus Amphidinium. Too little data are given to place it elsewhere
with any degree of certainty.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 133

Amphidinium asymmetricum sp. nov.
Plate 1, figure 1; text figure U, 5

Dr1AGnosis.— Body asymmetrically ellipsoidal, longest on its left side, epicone
very asymmetrical; girdle a steep spiral, deflected posteriorly at both ends;
sulcus confined to the hypocone; chromatophore yellowish, ramifying; littoral
habitat. Length, 48-52». Pacifie off La Jolla, California, July.

DEscrIPTION.—The body is asymmetrically ellipsoidal, subcireular in cross-section, flattened
dorsally, rotund laterally and ventrally, its transverse and dorsoventral diameters about equal
throughout the middle third of the body. The epicone is very asymmetrical, its length at its left
side only 0.1 and at the right ventral region nearly 0.5 of the total length. The apex is asym-
metrically rounded in ventral view and flattened in the dorsal half in lateral view. Its total
volume is about 0.2 that of the whole body. The hypocone is sack-shaped, more symmetrical than
the epicone, but still shows some elongation in the left dorsal region homologous with that of
the longer left horn of Ceratium and many other Dinoflagellata. Its greatest length is 1.6 trans-
diameters and is found mid-dorsally. The antapex is broadly rounded but longest at the left and
dorsad to the main axis.

The girdle is a rounded trough, ascending about 5 furrow widths from the flagellar pore to
the dorsal region, passing horizontally across this and descending thence in a uniform slope of
30° on the right face, increasing to 40° on the ventral face in its own distalmost part. Its total
displacement between the proximal and distal regions is nearly 0.5 transdiameter. The transverse
flagellum completely encircles the body. The length of the suleus is 0.68 of the total length. It
turns to the left anteriorly, and becomes a deep fold in the median plane through the hypocone.
It does not extend upon the epicone. Its left border forms a flap which overhangs its right side.
The longitudinal flagellum extends posteriorly beyond the antapex for 0.7 of the total length.
The posterior flagellar pore is hidden in the deep suleus.

The surface is faintly striate with fine parallel lines equidistant on both epicone and hypocone,
and about ten on the radius. The amyloid body is spheroidal, homogeneous in appearance in
life, 0.28 transdiameter in diameter, and centrally located. It is surrounded by a halo of sparsely
scattered subspheroidal, highly refractive, oil globules and the whole is enclosed in an unusually
large and continuous chromatophore with blunt, finger-like, peripheral processes which radiate
in all directions to the surface. Its color is a uniform pale yellow ochre. The nucleus was not
certainly located. It probably les posterior to the amyloid body as in A. operculatum.

DiMEnsions.—Total length, 50“; transverse diameter at widest point, 30+;
dorsoventral diameter, 28; diameter of amyloid body, 7.5.

OccuRRENCE.—Moderately frequent in washings from beach sand on the
ocean beach at La Jolla, California, in July, 1914.

JOMPARISONS.—This species is a divergent type of Amphidinium, not far
from the Gyrodinium-like species of Gymnodinium in respect to the large size
of the epicone. The striations are similar to those frequently found in Gyro-
dinitum. It has been placed in Amphidinium because of (1) the asymmetry of
the epicone, which is marked and in the same direction as in A. operculatum;
(2) the deep ventral sulcus and left flap; and (8) the arrangement of the
chromatophore with respect to the amyloid body. All these features are so
consistently indications of Amphidinium that the shghtly excessive size of the
epicone may be safely disregarded, especially since intermediate stages in size

134 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

of epicone are found in A. truncatum, A. scissum, and A. sulcatum (figs. U,
3, 1,10). The species is thus a divergent member of the section of the genus
having the larger epicone.

Amphidinium corpulentum sp. nov.

Plate 1, figure 11; text figures U, 6, 13

Dracnosts.—A small species with body stout, elongated rotund, its length
1.55 transdiameters, dorsoventrally compressed to about 0.5 transdiameter ;
epicone about 0.25 of the total length, girdle anterior, sulcus extending around
apex of epicone to antapex with left flap on hypocone, color ochraceous, littoral
habitat. Length, 46-54». Pacific at La Jolla, California, July.

DEscrIPTION.—The body is stout, sack-shaped, its length 1.5-1.6 transdiameters, flattened
dorsoventrally to about 0.5 transdiameter. Epicone 0.20—0.25 of the total length, subconical in
outline with slightly convex sides forming an angle of 30° in ventral and 60° in lateral view.
Its diameter almost equals that of the epicone. Its height is 0.66 of its base in lateral view and
0.60 of the base in its greatest ventral extension. Its apex is broadly rounded and partially
encircled by the terminal loop of the anterior end of the suleus. The hypocone forms 0.75—0.80
of the total length and has straight sides for 0.75 of its length. The antapex is broadly rounded
in a flattened semicircular outline seareely notched by the distal end of the suleus.

The girdle curves sharply anteriorly at its proximal end at an angle of 45°, reaching the
horizontal at the end of the first quarter of the turn, continues horizontally to its distal quarter,
where it turns posteriorly at an angle of 30° without much curvature to its junction with the
suleus. Its displacement posterior to its proximal end is about a furrow’s width. The V-shaped
junction is thus markedly asymmetrical. The furrow is deeply incised with prominent lips.
The anterior flagellar pore opens at the junction of girdle and suleus. The suleus extends the
full length of the body in an almost rectilinear course from the antapex anteriorly upon the
epicone to within less than two furrows’ width of the apex, where it makes an abrupt turn to
the left and forms a faint semicircle about the left side of the apex. It sinks deeply into the
hypocone and its left margin forms an overhanging flap. It flares distally at the antapex in a
broad posteroventral excavation. The longitudinal flagellum arises from the posterior flagellar
pore at a point about 0.33 of the length of the hypocone posterior to the distal end of the girdle.
It projects beyond the body for a distance equal to 0.75 of the total length of the body.

The surface has no evident striations. The nucleus, in the individual shown in the figure,
was elongate, narrowly reniform, and was located in the right half of the epicone with its longer
axis parallel to the major axis of the body. Its length nearly equals the transdiameter and its
diameter was about 0.3 its length. The body was packed, especially in the peripheral regions,
with numerous small rounded ochraceous chromatophores which gave to the whole body a diffuse
pale yellow ochre tone. Pusules, amyloid body and oil globules were not noted.

Divensions.—Total length, 46-54; greatest transdiameter, 30-34; dorso-
ventral diameter, 17+; length of nucleus, 26—30+.

OccuRRENCE.—This species was found throughout July, 1914, in beach sand
off La Jolla, California. It was especially abundant during the latter half of
the month.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 135

Repropuction.—Among the numerous individuals under observation one
pair (text fig. U, 13) was found in what appeared to be a late phase of conju-
gation. This conjecture is based upon the correctness of Stein’s figures (1883,
pl. 17, figs. 25-27) of conjugation in Amphidinium lacustre. In his figures and
in our pair the two individuals are fused together in the regions of the ventral
pores and are slightly displaced anteroposteriorly. One pair could not be separ-
ated by manipulation and both in life and after fixation in Bouin’s fluid and
staining in borax carmine was found to contain only a single spheroidal nucleus.

In view of the lack of reliable information regarding fission, and especially
concerning the occurrence and manner of sexual reproduction in the Dinoflag-
ellata, it is quite possible, indeed highly probable, that this is only an early
stage in approaching binary fission in which the motor organs have divided but
the nucleus is still in the prophase. This sequence in the phenomenon of fission
is the usual one among some of the Euflagellata (see Kofoid and Swezy, 1915).

Compartsons.—The grounds for including this species in the genus Amphi-
dinitum are at best but slight. The only morphological grounds are (1) the
left flap of the suleus, (2) the dorsoventral compression, and (3) the relatively
small size of the epicone. These characters are found in whole or in part in
A. truncatum, A. scissum, A. asymmetricum, and A. dentatum (figs. U, 3, 1,
5, 4).

The relationships thus established appear to be more significant than the
form of girdle, which is the one character relating the species to Gymnodinium.
It is obvious, however, that the inclusion in Amphidinium of a species with so
large an epicone as that in A. corpulentum will necessitate an emendation to
the characteristics of the genus as defined by Schiitt (1896).

Amphidinium corpulentum has a form of sulcus similar to that of A. scissum
encircling an apical lobe on the epicone, a left ventral flap along the sulcus as
in A. asymmetricum and dorsoventral compression as in A. scissum and A,
truncatum. It belongs, therefore, in that section of the genus.

Amphidinium crassum Lohmann
Text figure U, 18

Amphidiniwm crassum Lohmann (1908), pp. 252, 261, 262, 366, 368, pl. 17, fig. 16; (1911),
pp. 30, 31, fig. 12g.

A. crassum, Paulsen (1908), p. 96, fig. 130.

A. crassum, Herdman (19110), p. 71; (1911c), p. 38.

A. crassum, Ostenfeld (1913), p. 388.

A. crassum, Lebour (1917a), table 1; (19176), p. 188, fig. 2.

A. crassum, Lemmermann (1910), p. 615.

DiaGnosis.—A minute species with ovoidal body, its length 1.50 trans-

diameters; girdle anterior; epicone minute. Length, 27. Baltic Sea off Kiel,
Germany, throughout the year.

136 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

DerscriPTioN.—Body broadly oval, rounded posteriorly and pointed anteriorly, its length 1.59
transdiameters at the widest part. The epicone is a minute eaplike portion having a length of
0.16 of the total length of the body. It is conical in shape (90°) with a sharply pointed apex.
The hypocone is rotund ovoidal with broad rounded antapex, widest about its middle, and in
length 0.67 of the total length.

Lohmann’s (1908, 1911) figures are both apparently dorsal views which show the girdle
passing transversely across the body and give no indication of the suleus. The girdle is wide,
0.17 transdiameter, and rather deeply impressed. Its distance from the apex is about 0.16 of the
total length of the body.

The nucleus is a small ellipsoidal body lying near the antapex. Its major and minor axes
are about 0.4 and 0.8 transdiameters, respectively. The central part of the cytoplasm is usually
occupied by a large, yellow brown body, probably a food body. The remainder of the eytoplasm
contains numerous minute spherules.

Divenstons.—Length, 27; transdiameter, 17+; axes of nucleus, 7 and 5+.

OccURRENCE.—Figured by Lohmann (1908, 1911), from the Baltic Sea off
Kiel, Germany. He records it as being present throughout most of the vear.
The only other record of its occurrence is that of Lebour (1917b) from Ply-
mouth Sound, England.

Amphidinium cucurbita sp. noy.
Plate 1, figure 9; text figures U, 12, W, 3

Draanosts.—A large species with rotund ellipsoidal body, its length 1.46

transdiameters, girdle far anterior with no displacement; sulcus extends from

girdle to antapex; surface with both striae and furrows; color yellow. Length,
1104. Pacifie off La Jolla, California, June to August.

Descrition.—The body is rotund ellipsoidal, with broad apices, its length 1.46 transdiam-
eters at the widest part. The epicone occupies only a minute portion of the body, its length on
the dorsal and lateral sides being about 0.07 of the total length of the body. It extends posteriorly
on the ventral side for a length of 0.36 of the total length, forming a triangular portion of about
55°. Its greatest width is 0.56 of the transdiameter of the hypocone. In ventral view it thus
forms the sector of a hemisphere. The hypocone has a length on the dorsal and lateral faces of
the body of 0.9 of the total length of the body. Its sides are subparallel for the middle third of
their length, the posterior third being hemispherical and the anterior sloping to the girdle. Both
the apex and antapex are broadly rounded, almost flattened, the latter being sometimes slightly
indented by the suleal notch.

The girdle is placed far anteriorly, its distance from the apex on the dorsal and lateral sides
being about 0.07 of the total length of the body. Ventrally both ends of the girdle turn abruptly
posteriorly to meet the girdle at a distance of 0.36 of the total length of the body from the apex.
The ends are without displacement. The furrow is narrow and deeply imbedded with sharp-
angled borders. The sulcus extends from the girdle to the antapex as a deep, narrow trough, the
sides of which become widely deflected near the posterior end of the body. Its depth also
inereases posteriorly, until it has a depth of nearly 0.5 of the dorsoventral diameter of the body.
Its sides are smoothly rounded and in front of the posterior pore may overlap sufficiently to
obscure the furrow. The anterior flagellar pore opens at the junction of the girdle and suleus
and the posterior pore a short distance from the antapex.

The nucleus is reniform in shape and is located in the posterior portion of the body. Its
chromatin structure could not be analyzed. Its major and minor axes are 0.45 and 0.26 trans-
diameters respectively.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 137

A small club-shaped pusule opens into each flagellar pore. The cytoplasm is coarsely granular,
with a great complexity of structure in all the individuals observed. The midventral portion
of the body in the region of the pusules is usually filled with numerous small, dark, refractive
granules. Most of these have been omitted in the figures for the sake of clearness. Dorsad from
these are large vacuoles, and radiating out from them towards the surface of the body are
numerous long, slender greenish rodlets interspersed between long, narrow vacuoles. Both the
anterior and posterior regions are filled with large vacuoles or food masses. Small oil droplets
are scattered through the remaining cytoplasm.

Vacuoles containing fluid of the same pink color as the pusules are usually present. The
general color is a deep, rich yellow.

The surface of the body on the hypocone is marked with deep, parallel furrows, about 20 in
number in the cireuit of the body. These may be arranged in groups of 3, 1, 5, or may be
equidistant. They usually die out before reaching the girdle and the antapex. Between the
furrows are found fine equidistant, parallel surface lines of dots, usually about eight between
furrows.

Dimenstons.—Length, 95 to 110; transdiameter, 75“; axes of nucleus, 32
and 234,

OccurRRENCE.—The first individual was taken July 12, 1917, 4 miles off La
Jolla, California, in a haul from 80 meters to the surface and in a surface
temperature of 20°5 C. Three individuals were recorded July 20, in a haul 6
miles offshore from 80 meters to the surface and in a surface temperature of
21° C. Four more were taken July 27, 4 miles offshore at the same depth and
at a surface temperature of 21°9 C. The same number was again observed
August 21, in a catch taken 5 miles offshore, in a haul from 83 meters to the
surface and in a surface temperature of 21°6 C.

Comparisons.—This is by far the largest species of Amphidinium thus far
described. It presents undoubted affinities with that group, however, as shown
by the relatively small, operculum-like epicone. Its large size, rotund habit,
and presence in the deeper oceanic waters make it a possible connecting link
with Gymnodinium. It also exhibits cytoplasmic differentiation similar to that
found in G. dogieli and G. costatwm, and without parallel elsewhere in the genus
Amphidinium.

Amphidinium cucurbitella sp. nov.
Plate 1, figure 6; text figure U, 30

DraGnosis.—This is a medium sized species with broad almost biconical
body, its length 1.6 transdiameters; girdle anterior, without displacement;
suleus extending from girdle to antapex; surface striate and furrowed; color
green, holozoic. Length, 85. Pacific off La Jolla, California, July.

Drscript1ioN.—The body is broadly ellipsoidal, approaching biconical (50°), widest in the
middle and tapering towards both apices, its length 1.6 transdiameters at the widest part, sub-
circular in cross-section. The hypocone greatly exceeds the small epicone, its length being greater
by 0.53 of its own length. The epicone is small, rounded, caplike, with a longer, pointed ventral
portion. It has a length above the anterior flagellar pore on the ventral side of 0.36 and on the
dorsal side of 0.2 of the total length of the body. The hypocone has a length on the dorsal side

138 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

of about 0.79 of the total length of the body. It is narrowed anteriorly to about 0.66 of its widest
transdiameter, which is at the equator of the body midway between the apices. It tapers poster-
iorly to the rounded antapex, which is narrower and more pointed than the apex.

The girdle is anterior in position, its distance from the apex being 0.2 of the total length of
the body on the dorsal and lateral sides. Ventrally both sides of the girdle are deflected poster-
iorly until they meet the sulcus at about 0.36 of the total length of the body from the apex. The
furrow is a narrow, rather shallow depression with smoothly rounded borders. The suleus is a
narrow trough extending from the girdle to the antapex. The anterior flagellar pore is located
at the junction of the girdle and suleus, the posterior pore at a point about 0.6 of the distance
between the junction and the antapex.

The nucleus is a relatively small, spherical body found in the posterior portion of the hypocone.
It is filled with fine, moniliform chromatin strands. Its axis is about 0.37 transdiameter. Small
elub-shaped pusules open into each flagellar pore. The cytoplasm is finely granular, densely
so in the central portion of the body, with numerous blue green oil droplets scattered through it.
In the anterior end of the body a large vacuole is found and behind it a large food mass enclosed
in a vacuole. The general color of the organism is a yellow green with a trace of orange in the
denser parts. The surface is finely striate with minute blue green rodlets arranged in a linear
series. interspersed at every third row with continuous lines, equidistant and longitudinal. In
additon the surface of the hypocone is deeply impressed with longitudinal, parallel grooves.
These are arranged in groups of four and are relatively short, fading out before reaching the
girdle and antapex. None could be detected on the epicone.

Divensions.—Length, 85; transdiameter, 53+; diameter of nucleus, 20+.

Location.—This was first seen July 20, 1906, in a surface haul made with
a No. 20 net, 1.5 miles off La Jolla, California. Two individuals were taken
July 27, 1917, 4 miles off La Jolla, in a haul from 80 meters to the surface and
in a surface temperature of 21°9 C.

Comparisons.—This species and A. cucurbita are the only ones in the genus
which present the peculiar combination of deeply marked furrows and fine
striae on the surface. These differ shghtly in the two species. The cytoplasmic
structure is simpler in this species than in A. cucurbita, yet presents the same
evidences of holozoic nutrition.

Amphidinium dentatum sp. noy.
Plate 10, figure 111; text figure U, 4

Dracnosis.—A small species with body broad, almost squarish in ventral
view, dorsoventrally compressed, its length 1.25 transdiameter ; girdle anterior,
without displacement; sulcus extending from girdle to hypocone; blue green
chromatophores; littoral habitat. Length, 404. Pacific at La Jolla, California,
August.

Description.—The body has an almost squarish outline in ventral view, dorsoventrally com-
pressed to about 0.5 transdiameter, widest in the middle, its length 1.25 transdiameters at the
widest part. The epicone is small, triangular in ventral view with a width of 0.75 transdiameter.
Tt extends posteriorly on the ventral side about 0.3 of the total length of the body, its sides
forming an angle of 70°. It is slightly asymmetrical with the left side higher than the right.
The apex is a short, toothlike, dextrally flexed projection. The hypocone is broad and rotund

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 139

ventrally, with the left side longer and slightly less convex than the right. The antapex is exea-
vated ventrally by the suleal notch, broad and rounded on the dorsal side, the right and left
borders of the suleus extending posteriorly in slender, toothlike points.

The girdle is somewhat asymmetrical in position, located about 0.1 of the total length of the
body below the apex on the dorsal side, with the distance less on the left and slightly greater on
the right sides. Ventrad, both ends turn posteriorly and meet at a point distant from the apex
about 0.3 of the total length of the body. The furrow is wide, about 0.09 transdiameter, and
deeply impressed, with overhanging borders. The suleus extends from the girdle to the antapex
in a slightly sinuous line which flares widely in the distal half of its course, at the same time
expanding dorsad, deeply excavating the ventral part of the body. The anterior flagellar pore
opens at the junction of the girdle and suleus, the posterior pore slightly posterior to the mid-
point between girdle and antapex.

The nucleus is an ellipsoidal body found on the left side of the suleus below the girdle. Its
major and minor axes are about 0.46 and 0.25 transdiameters in length, respectively. A large
sacklike pusule opens into each flagellar pore. These are connected below their openings by a
slender canal. The cytoplasm is clear and colorless. In the peripheral layer are numerous,
disklike chromatophores of a dull, blue green color and many minute, dark, highly refractive
granules. No striae or other surface markings could be detected.

Diwenstons.—Length, 40”; transdiameter, 32“; axes of nucleus, 15 and 8».

OccuURRENCE.—This species was found in the beach sand at La Jolla,
California, in August, 1917.

CoMPaARISONS.—This species has much in common with A. truncatum (fig.
U, 3). The size and shape of the epicone and the lack of surface striae serve,
however, to set it apart from that species.

Amphidinium discoidalis Diesing
Text figure U, 23

Amphidinium operculatum Claparéde and Lachmann (1858-61), p. 411, pl. 20, fig. 12 only.
A. operculatum var. discoidalis Diesing (1866), p. 98 (384).

Dracnosis.—A small species with broadly ovoidal body, its length, 1.13 trans-
diameters; girdle anterior; sulcus (?); colorless. Length, 47. North Sea on
the coast of Norway.

DeEscription.—The body is broadly ovoidal, widest posteriorly, its length 1.13 transdiameters
at the widest part. The epicone is minute, with a length of about 0.05 of the total length of the
body. The apex is broad and truneate. The hypocone is: very broad posteriorly, narrowing
anteriorly, with broad, rounded antapex. <A dorsal view only of this form is given by Claparéde
and Lachmann (1858-61), hence the structure of the ventral surface is unknown. The girdle is
far anterior and passes transversely across the dorsal side of the body. Its distance from the
apex is about 0.05 of the total length of the body. The cell contents as figured by Claparéde and
Lachmann consist of a few spherules and rod-shaped bodies, probably oil drops and food masses.

Dimenstons.—Length, 47+; transdiameter, 41+.
OccuRRENCE.—Figured by Claparéde and Lachmann (1858-61) from the
North Sea on the coast of Norway.

140 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

SynonyMy.—This was figured by Claparéde and Lachmann as a form of
Amphidinium operculatum, possibly a different species. Diesing (1866) names
it Amphidinium operculatum var. discoidalis. Its final disposition awaits re-
examination of Norwegian material. It appears to be near A. herdmani.

Amphidinium emarginatum Diesing
Text figure U, 21

Amphidinium operculatum var. Claparéde and Lachmann (1858-61), p. 411, pl. 20, fig. 11.
A. operculatum var. emarginata Diesing (1866), p. 98 (384).

DrtaGNnosis.—A minute species, with broadly ovoidal body, its length 1.1
transdiameters; girdle anterior; sulcus (?); colorless. Length, 24". North Sea
on the coast of Norway.

Description.—The body is broadly ovoidal, widest posteriorly, its length 1.1 transdiameters
at the widest part. The dorsal side only is figured by Claparéde and Lachmann (1858-61), hence
the course of the girdle on the ventral side as well as the suleus are unknown. The epicone is a
minute, caplike portion at the anterior end marked off from the rest of the body by the girdle.
It has a length of 0.07 of the total length of the body. The apex is truncate. The hypocone is
somewhat spatulate. Its anterior end has a width of 0.36 of the greatest transdiameter of the
body. The apex is broad, almost subtruneate.

The girdle passes transversely across the body at the anterior end, its distance from the apex
being 0.07 of the total length of the body. A few rounded spherules occupy the middle portions
of the body. Nucleus and pusules are not figured.

DimeEnsions.—Length, 24; transdiameter, 21+.

OccuRRENCE.—Figured by Claparéde and Lachmann (1858-61) from the
North Sea off the coast of Norway.

SynonyMy.—This was described by Claparéde and Lachmann (1858-61) as
Amphidinium operculatum variety, possibly a different species. Diesing (1866)
describes it as Amphidinium operculatum var. emarginata (Clap. and Lach.).
It is near A. herdmani. Its final disposition awaits re-examination of Nor-
wegian material.

Amphidinium fastigium sp. noy.
Plate 2, figure 18; text figure U, 11

Driacnosis.—A large species with irregularly ellipsoidal body, its length 1.61
transdiameters; girdle without displacement ; sulcus extending to antapex; color
grey green. Length, 1024. Pacific off La Jolla, California, June, July.

Description.—The body is irregularly ellipsoidal, slightly pointed anteriorly, broadly rounded
posteriorly, its length 1.61 transdiameters at the widest part. Its transdiameter and dorso-
ventral diameter are subequal. The epicone has the shape of a low, broad cone with the apex
more or less flattened and a deep, wide trough extending down the ventral face. Its length on
the dorsal and ventral sides is 0.3 and 0.4 of the total length of the body respectively. The

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 141

hypocone is an irregular sacklike body with a deep groove on the proximal part of the ventral
face and a shallow one on the distal part of the dorsal face. The antapex is broad and rounded.

The girdle lies at a distance from the apex on the dorsal and ventral sides of 0.3 and 0.4 of
the total length of the body respectively. The furrow is wide, about 0.06 transdiameter, and is
deeply impressed, undercutting the anterior border and smoothly curving out to the posterior
one. Both lips are outlined by a double-contoured, blue green line. The exact relations of the
suleus are difficult to distinguish. It seems to invade the epicone at the base of the trough which
indents its ventral face. Posteriorly it extends to within a short distance of the antapex. The
anterior flagellar pore is found at the junction of girdle and sulcus, and the posterior pore a
short distance in front of the antapex.

The nucleus is an ellipsoidal body filled with moniliform chromatin strands. It is slightly
posterior to the central part of the organism. Its axis is about 0.36 transdiameter in length.

The cytoplasm is finely granular and rather dense in appearance. In the central part of the
body is a mass of dark, refractive granules. Anteriorly is a large body of greyish color, pre-
sumably a food mass, and nearer the center a larger, reddish brown body. Posterior to the
nucleus are other bodies grey and reddish brown in color. A few small spherules and minute
refractive granules are scattered through the remainder of the cytoplasm. The general color
of the organism is dull grey green. The surface of the body is marked by a few double-contoured
lines or ridges, about five on one face of the hypocone, fewer on the epicone. These extend from
the girdle to the apices.

DrMensions.—Length, 102; transdiameter, 634; axis of nucleus, 23+.

OccURRENCE.—This species was first seen in a surface haul made at the end
of the pier at the Biological Station at La Jolla, California, June 26, 1917. On
July 25 it was taken in a haul 11 miles offshore, from 80 meters to the surface
and in a surface temperature of 21°75 C. On July 27 it was noted in a haul
taken 4 miles offshore, from 80 meters to the surface and in a surface temper-
ature of 21°9 C.

Comparisons.—This is an aberrant species, Amphidinium-like in the relation
of epicone and hypocone, yet possessing characters which clearly mark it off
from the other species of that genus. In one individual noted, a stout, laterally
projecting tentacle was thrust out from the distal part of the sulcal area. This
greatly resembled the prod of Hrythropsis. The individual possessing it was
not active, so that nothing can be said as to its motility or normality. It was
possibly only a temporary protoplasmic process.

Amphidinium galbanum sp. nov.
Plate 1, figure 4; text figure U, 29

Draanosis.—A small species with subcylindrical body, its length, 1.92 trans-
diameters; girdle anterior, displaced 0.44 transdiameter, sulcus extending from
near apex to antapex; surface furrowed; bright green yellow chromatophores.
Length, 48. Pacific off La Jolla, California, July.

DescripTion.—The body is small, subeylindrieal with the anterior end forming a conical cap,
the posterior end rounded, slightly wider anteriorly, its length 1.92 transdiameters at the widest
part. The hypocone greatly exceeds the epicone in size, its length being greater by 0.63. The

142 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

epicone has the shape of a broad, flat cone of about 105° with blunt apex. Its length is about
0.22 of the total length of the body, exeept for a slender point extending posteriorly on the right
side of the suleus with a length of 0.45 of the total length. The hypocone is long, with a length
of 0.73 of the total length of the body. Its sides are subparallel for about 0.7 of their extent,
flaring slightly around the girdle and rounded posteriorly to the broad, symmetrical antapex.

The girdle encircles the body near the anterior end. Its proximal end joins the suleus at a
distance from the apex of 0.22 of the total length of the body. It passes around the body trans-
versely for about 0.8 of a turn, when it is abruptly deflected posteriorly, with a displacement of
0.44 transdiameter, meeting the sulcus at an angle of about 45°. The furrow is about 0.12 trans-
diameter in width, and deeply impressed. The sulcus begins a short distance from the apex and
extends posteriorly to the antapex in a slightly sinuous course. The trough is shallow anteriorly,
deepening posteriorly with a wide flare of the borders in the antapical region. The anterior
flagellar pore is found at the proximal junction of the girdle and suleus, the posterior pore about
midway between the distal junction and the antapex.

The nucleus is a relatively large, spheroidal body in the posterior half of the hypocone. It is
filled with fine beaded chromatin strands. Its axis is 0.52 transdiameter.

A small sacklike pusule opens into each flagellar pore. The cytoplasm is granular and alveolar
in structure, with relatively coarse alveoh. This is omitted in the figures for the sake of clearness.
The color of the cytoplasm is pearl grey. In the peripheral layer are numerous blue green oil
droplets and leaflike, bright green yellow chromatophores. These are placed closely together
through the entire peripheral layer of the cytoplasm. The surface of the body is marked by
longitudinal grooves, about twelve in number, across one face. On the epicone these are radially
arranged around the apex and die out before reaching the girdle. On the hypocone they are
subparallel, fading out before reaching the girdle and the antapex.

Diwenstons.—Length, 48-67; transdiameter, 25-32; diameter of nucleus,
14z.

OccuRRENCE.—The first individual was taken July 20, with a No. 25 silk net,
6 miles off La Jolla, California, in a haul from 80 meters to the surface and in
a surface temperature of 21° C. A second one was taken July 24, 2.75 miles off
La Jolla, in a haul 80 meters to the surface and in a surface temperature of
21°9 C.

Comparisons.—Like A. cucurbita this species stands near the border line
dividing Amphidinium from Gymnodinium. The relatively minute size of the
epicone places it with the former genus rather than with the latter.

Amphidinium globosum Schréder
Text figure U, 20
Amphidinium globosum Schroder (1911), pp. 616, 651, fig. 16.
A. globosuwm, Schiller (1912), p. 493.

SynonyMy.—This form was figured by Schroder (1911) from the Adriatic
Sea near Rovigno, Austria. It is almost globular in form with minute brown
chromatophores, the length of the hypocone being only twice that of the epicone.
The relation of epicone and hypocone is not the characteristic one of the genus
Amplhidinium, and is sufficient to make its inclusion with that genus doubtful.
The data given are too slight to place it with any degree of certainty, at least
until its characteristics have been more fully analyzed.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 143

Amphidinium herdmani nom. sp. noy.
Text figure U, 2

Amphidinium operculatum, Herdman (1911a), p. 554; (19116), pp. 71-75, pl. 8; (1911c),
pp. 38-47, figs. 23-26; (1912), pp. 28-36, figs. 8-11; (1913), pp. 19-23, fig. 6.

Dracnosis.—A small species with broadly ellipsoidal body in ventral view,
dorsoventrally compressed, its length 1.16 transdiameters; girdle anterior;
sulcus extending from girdle to antapex; color bright yellow. Length, 50.
Trish Sea, beach sand at Port Erin, Isle of Man, April to November.

DEscrIPTION.—The body is broadly ellipsoidal in ventral view, dorsoventrally flattened,
rounded posteriorly and truncate anteriorly, its length 1.16 transdiameters at the widest part.
The epicone is a small triangular-shaped portion at the anterior end of the body, with a length
on the dorsal side of 0.06, and on the ventral side of the body of 0.36 of the total length of the
body, its greatest width being 0.53 transdiameter. The borders of the ventral portion converge

posteriorly at an angle of 70°. The apex is truncate. The hypocone is broad with rounded sides
and a broad, rounded, slightly notched antapex.

The girdle is placed far anteriorly, its distance from the apex being about 0.06 of the total
length on the dorsal side of the body. On the ventral face both ends of the girdle turn posteriorly
for a distance of 0.36 of the total length of the body and meet without displacement. The furrow
is about 0.06 transdiameter in width, and deeply impressed with overhanging borders. The
suleus extends from the girdle to the antapex, wide at its beginning, contracted below and ex-
panding as it nears the antapex, where it sometimes forms a deep notch. The transverse and
longitudinal flagella arise near each other at the junction of the girdle and sulcus, probably from
the same pore.

Nucleus and pusules are not figured by Herdman (1911b, c). The central part of the
cytoplasm is occupied by a small, spherical body containing a central granule, from which
radiate out to the periphery long, slender chromatophores (?), bright yellow in color. No striae
recorded.

Dimensions.—Length, 504; transdiameter, 45.

OccuURRENCE.—This species has been figured by Herdman (1911, 1912, 1913),
from the Irish Sea at Port Erin, Isle of Man, from April to November. It
occurred as greenish brown patches on the sandy beach, a little below high water
mark, the largest of which was 50 yards long by 5 yards wide. None was found
in the shallow waters offshore. These patches were present from a few days
to a couple of weeks, when they would disappear to reappear several weeks later.

SynonyMy.—It was described by Herdman (1911) as Amphidiniwm oper-
culatum Clap. and Lach. It differs from that species, however, in its propor-
tions, having a broader body, a wide, truncate apex, and a greater length in the
epicone; it differs also in its coloring, which is bright yellow. It is therefore
proposed as a separate species with the name Am phidinium herdmant nom.
sp. nov.

ComPariIsons.—This species resembles A. truncatum (fig. U, 3) in its broad,
truncate apex, but differs widely from it in all other respects. Its type of
chromatophores is that of A. operculatum and A. steini (figs. U, 25, 28).

144 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Amphidinium klebsi nom. sp. noy.
Text figure U, 14

Amphidinium operculatum, Klebs (1884), pp. 723, 726, 732, 739, pl. 10, figs. 11, 12.
A. operculatum, Paulsen (1908), p. 96, fig. 128.

DraGnosis.—A small species, with subcylindrical body, its length 1.72 trans-
diameters; girdle anterior; chromatophores (?). Length, 46. Bay of Naples,
early spring months.

Description.—The body is subeylindrical (dorsoventrally compressed ?), rounded posteriorly,
subtruneate anteriorly with the middle portion drawn out in a slender tongue deflected to the
left. The length of the body is 1.72 transdiameters at the widest part. The tongue-shaped
portion at the anterior end is the epicone, which is separated from the rest of the body by the
wide girdle. The exact limits of the girdle and epicone are not shown in Klebs’s figures (1884).
Its length above the base of the girdle is about 0.2 of the total length of the body, its width about
0.35 transdiameter. The hypocone is subeylindrical (flattened dorsoventrally?) with its sides
subparallel for the middle third of their extent, rounded above and below. The antapex is broad
and slightly rounded, while anteriorly the sides of the hypocone below the girdle swell forward
and outward, forming wide, high shoulders, the left one narrower than the right.

The girdle is a wide cirele embracing the narrow, necklike portion at the anterior end of the
body. Its width is about 0.25 transdiameter. Its proximal border, as well as the suleus, and the
connections of girdle and suleus are not indicated in Klebs’s figures (1884). The longitudinal
flagellum arises a short distance below the probable point of union of girdle and suleus. The
transverse flagellum arises in his figure on the right dorsal side of the body, a condition un-
paralleled in the dinoflagellates and one which is probably an error of drawing or interpretation.

The nucleus is a large, spherical body occupying the posterior half of the hypocone. Its axis
is 0.43 transdiameter in length. The cytoplasm is filled with spherules of varying size and long,
tapering chromatophores (?), which radiate forward and outward from the region of the nucleus
in the posterior part of the body. The color of the organism is not noted by Klebs. The surface
is apparently marked by a few longitudinal furrows or striae extending the length of the hypocone.

Drvenstons.—Leneth, 46; transdiameter, 284; axis of nucleus, 15.

OccURRENCE.—Figured by Klebs (1884) from the Bay of Naples, where it
appeared in large numbers in the early spring months.

SynonyMy.—This form was figured by Klebs (1884) as Amphidiniwm oper-
culatum Clap. and Lach. It differs from that species in its narrowly constricted
girdle, tonguelike epicone, chromatophores radiating from the posterior end of
the body and the furrows on its surface. It differs as widely from Herdman’s
(1911) and Stein’s (1883) forms of the same species. It is therefore proposed
to give it species rank with the name Amphidinium klebst nom. sp. nov.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 145

Amphidinium lacustre Stein
Text figure U, 15

Amphidinium lacustre Stein (1883), p. 15, pl. 17, figs. 21-30.

A. lacustre, Biitsechli (1885), pp. 940, 993, pl. 54, fig. 7.

A. lacustre, Pouchet (1885), p. 54.

A. lacustre, Schilling (1891), p. 62; (1913), p. 14, fig. 9.

A. lacustre, Mez (1898), p. 217.

A. lacustre, Ludwig (1898), p. 299.

A. lacustre, Schodnichen and Kalberlah (1900), p. 230, pl. 8, fig. 2; (1909), p. 251, pl. 8,
fig. 2.

A. lacustre, Lemmermann (1900), p. 115; (1903), p. 260; (1910), pp. 580, figs. 8-13, 616,
617.

A. lacustre, Zederbauer (1904), p. 2

A. lacustre, Senft (1905), p. 89, figs. 42-48.

A. lacustre, Liebetanz (1905), p. 36; (1910), p. 42, pl. 2, fig. 39.

A. lacustre, Kofoid (1907a), p. 301.

A. lacustre, Entz (1907), p. 24; (1909), p. 262.

A. lacustre, Ohno (1911), p. 91.

A. lacustre, Herdman (1911b), p. 39; (1911c), p. 72.

A. lacustre, Francé (1912), p. 28.

D1aGNosis.—A minute species with broadly ovoidal body, its length 1.25
transdiameters, antapex rounded; girdle anterior, without displacement; sulcus
extending from girdle to antapex; brown chromatophores. Length, 23. Fresh
water and brackish pools in Europe and Japan.

DescripTIoN.—The body is rotund ovoidal, rounded posteriorly, almost flattened anteriorly,
its length 1.25 transdiameters at the widest part. The epicone forms only a minute portion of
the body, its length 0.13 of the total length of the body and its width about 0.52 transdiameter
of the body. It forms a small rounded or somewhat flattened operculum-like lid separated from
the rest of the body by the broad girdle. The hypocone is heart-shaped in ventral view, its length
about 0.78 of the total length of the body, with a broad rounded antapex.

The girdle is anterior, forming a complete circle around the body about 0.13 of the total
length of the body from the apex. The furrow is about 0.1 transdiameter in width, and deeply
impressed. The sulcus is a furrow extending from the girdle to the antapex, wide anteriorly
and narrowing posteriorly. A thickening occurs on the right border at the proximal end. Stein
does not figure a transverse flagellum. The longitudinal flagellum arises at the junction of the
girdle and sulcus at a point marked by the presence of a spherical pusule.

The cytoplasm contains numerous minute spherules and several larger brownish chromato-
phores. No nucleus has been figured by Stein.

DimMensions.—Length, 23; transdiameter, 18.

OccuRRENCE.—Figured by Stein (1883) from fresh-water ponds and ditches
near Prague, Austria. The only other records of its occurrence are those of
Daday (Schilling, 1913, p. 14), who observed it in brackish pools near Déva,
Hungary, and Liebetanz (1910), who records its appearance in the stomach
contents (Panseninhalt) of four cows at Bern, Switzerland. All published
figures subsequent to those of Stein (1883) appear to be based on those of that
investigator.

146 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Comparison.—This is probably the fresh-water representative of a marine
species, A. turbo, both possessing some characteristics in common, the differences
being probably due to the change in medium.

Amphidinium lanceolatum Schréder
Text figure U, 9

Amphidiniwm (?) lanceolatwm Schroder (1911), p. 650, fig. 15.
A. lanceolatum, Schiller (1912), p. 493.

DraGNnosis.—A small species with slender body, tapering posteriorly, its
length 3.33 transdiameters; girdle far anterior; epicone minute, rounded, 0.33
transdiameter in width; sulcus not indicated; nucleus near center of body;
evtoplasm filled with spherules of varying sizes; colorless. Length, 30 to 35;
transdiameter, 94. Adriatic Sea near Rovigno, Austria.

Schroder (1911) questions the inclusion of this form with Amphidinium.
His data, unfortunately, are very meager and need confirmation, but the minute
size of the epicone, separated by the girdle from the elongated body, suggests
the usual relations of these structures in Amphidinium. It is therefore placed
in the genus, tentatively, until it has been found again and its structure more
fully determined. Its proportions are suggestively like those of Orytorum, but
there is no indication of a theca in either figure or description.

Amphidinium longum Lohmann
Text figure U, 7

Amphidinum longum, Lohmann (1908), pp. 252, 201, 262, 366, 368, pl. 17, fig. 15; (1911),
p. 31.

A. longum, Paulsen (1908), p. 96, fig. 181.

A. longum, Herdman (1911), pp. 71, 72; (1911), p. 38.

A. longum, Schréder (1911), pp. 625, 651.

A. longum, Lebour (1917b), p. 188.

Dr1aGnosis.—A minute species, with subovoidal body, its length 2.27 trans-
diameters; girdle anterior; epicone minute. Length, 254. Baltic Sea off Kiel,
Germany, July, August; Adriatic Sea near Lucietta, Austria-Hungary.

DescripTtioN.—The body is subovoidal, widest anteriorly behind the girdle, tapering slightly
posteriorly, its length 2.27 transdiameters at the widest part. The epicone is a minute triangular
portion with a sharply pointed apex, and a length of 0.12 of the total length of the body. The
hypocone is broad anteriorly, tapering posteriorly to a narrow, rounded antapex.

Lohmann’s figure (1908) shows what is apparently the dorsal side only, with no indication
of the course of the remainder of the girdle and the suleus. The girdle as figured is a broad
(0.27 transdiameter), deeply impressed furrow extending transversely across the body at a
distance from the apex of 0.12 of the total length of the body.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 147

The nucleus is a small, ellipsoidal body found near the antapex. It is filled with fine chromatin
granules. Its major and minor axes are about 0.55 and 0.36 transdiameters in length respectively.
A spheroidal food mass is usually present near the girdle region.

Dimenstons.—Length, 25; transdiameter, 11#; axes of nucleus, 6 and 4+.

OccURRENCE.— Figured by Lohmann (1908) from the Baltic Sea off Kiel in
July and August. The only other record of its appearance is that of Schroder
(1911) from the Adriatic Sea, near Lucietta off Austria-Hungary, July, in
vertical hauls of 100 and 200 meters.

RELATIONSHIPS.—It stands midway between A. lanceolatwm Schroder and
A. crassum Lohmann (figs. U, 9, 18). Its form suggests Oxrytoxum, but there
is no indication of a theca.

Amphidinium operculatum Claparéde and Lachmann
Text figure U, 25

Amphidinium operculatum Claparéde and Lachmann (1858-61), pp. 410, 411, pl. 20, figs.
910!

A. operculatum, Leuckart (1861), p. 152.

A. operculatum, Diesing (1866), p. 97.

A. operculatum, Fromentel (1874), p. 197.

A. operculatum, Maggi (1874), p. 119; (1880), pp. 5, 15.

A. operculatum, Saville-Kent (1880-82), p. 461, pl. 25, figs. 45-46.

A. operculatum, Bergh (1882), p. 694.

A. operculatum, Daday (1883), p. 477; (1884), pp. 5, 11, 12.

A. operculatum, Entz (1884), p. 239; (1896), p. 22; (1904), p. 112; (1907), p. 18; (1909),
p. 255.

A. operculatum, MeIntosh (1889), pp. 323, 337.

A. operculatum, Balbiani (1894), p. 257, fig. 41.

A. operculatum, Levander (1894c), p. 210; (1910), p. 41; (19016), pp. 8, 13, 18.

A. operculatum, Cleve (1894), p. 10.

A. operculatum, Schiitt (1895), p. 92.

A. operculatum, Tempére (1898), p. 127, pl. 15, fig. 8. Indeterminable.

A. operculatum, Florentin (1899), p. 334.

A. operculatum, Lemmermann (1900), p. 115; (1901), p. 358; (1910), p. 616.

A. operculatum, Massart (1901), p. 81.

A. operculatum, Calkins (1902), p. 432, fig. 27.

A. operculatum, Kofoid (1907a), p. 301.

A. operculatum, Cavers (1913), p. 180, fig. 8,, ..

A. operculatum, Griessmann (1913), pp. 3, 14.

Not Amphidinium operculatum, Stein (1883), Klebs (1884), Biitschli (1885), Schiitt
(1896), Sechréder (1900), Lemmermann (1903), Paulsen (1908), Herdman (1911a,
1911b, 1912, 1913).

Draanosis.—A small species with ellipsoidal, dorsoventrally flattened body,
its length 1.5 transdiameters; girdle anterior extending posteriorly on ventral
side; sulcus extending from girdle to antapex; vellow brown chromatophores.
Length, 454. Coast of Norway, west coast of Sweden, Atlantic off Woods Hole,
Mass.

148 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

DeEscripTion.—The body is broadly ellipsoidal in ventral view, narrowly so in side view, with
broadly rounded apices, its length 1.5 transdiameters at the widest part. The epicone is a
minute, triangular-shaped portion at the anterior end, its widest part about 0.4 transdiameter
of the body, and its greatest length about 0.3 of the total length of the body. The hypocone is
broadly rounded, narrowing slightly towards both ends.

The ends of the girdle meet at a point about 0.3 of the total length of the body from the apex.
It passes anteriorly at an angle of about 20° from the main axis of the body, turns transversely
across the dorsal side and thence posteriorly at an angle of about 25° with the main axis of the
body. The furrow is wide and somewhat deeply impressed. The sulcus begins at the junction
of the ends of the girdle and passes posteriorly to the antapex. The two flagella arise near each
other at the point of junction of girdle and suleus.

The nucleus has not been figured for this species by Claparéde and Lachmann (1858-61) or
by Calkins (1902). The central part of the body usually contains a small spheroidal body.
Radiating from this out to the periphery are long chromatophores, yellow brown in color.

Dimensions.—Length, 40 to 50+; transdiameter, 304; dorsoventral diameter,
5p.

OccURRENCE.—Figured by Claparede and Lachmann (1858-61) from collec-
tions made along the coast of Norway. Other records of its occurrence are as
follows: Entz (1896) from salt pools near Deva, Hungary, and Cleve (1894)
along the west coast of Sweden, Calkins (1902) at Woods Hole, Mass., Massart
(1901) in pools and ditches near Palingbrug, Belgium, and Griessmann (1913)
in laboratory cultures from sea water at Roscoff, France. No figures or de-
scriptions are given by Massart and Griessmann; hence the identity of their
forms must be held in doubt.

Amphidinium ovoideum Lemmermann
Text figure U, 19

Prorocentrum ovoideum Lemmermann (1896b), p. 147, figs. 1-3; as Amphidiniwm ovoi-
deum, (1900), p. 115; (1902), p. 260; (1910), p. 616, fig.

Amphidinium ovoideum, Paulsen (1908), p. 96.

A. ovoideum, Klebs (1912), p. 4388.

Dracnosis.—A minute species with broad, oval body, its length 1.25 trans-
diameters; girdle far anterior; sulcus (?); brown chromatophores. Length,
234. Brackish water, near Baltic Sea, Germany.

DescripTION.—The body is broadly oval to rounded, with broad apices, its length 1.25 trans-
diameters at the widest part. The epicone is minute, its length from the distal border of the
cirdle, 0.12 of the total length of the body and its greatest width 0.38 transdiameter. The apex
is broadly rounded. The hypocone is symmetrical, tapering at both ends, with broad, round
antapex.

Lemmermann’s figures (1896b). give only what is apparently the dorsal side, hence the
complete course of the girdle and the suleus cannot be traced. The girdle passes transversely
across the dorsal side at a distance from the apex of 0.12 of the total length of the body.

The nucleus is a spheroidal body found near the antapex. Its axis is about 0.38 transdiameter
in length. The body is filled with closely crowded, spherical, brown chromatophores. No striae
are recorded.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 149

DIMeEnstons.—Length, 17-23; transdiameter, 17-21; axis of nucleus, 5s.

OccuRRENCE.—Figured by Lemmermann (18960) from brackish, stagnant
water along the borders of the Baltic Sea near Plén, Germany.

SynonyMy.—This form was first described by Lemmermann (1896)) as
Prorocentrum ovoideum and the name afterwards (1900) changed to Amphi-
dinium ovoideum. Paulsen uses it as a synonym of Amphidinium operculatum
Clap. and Lach. In this, however, he is evidently mistaken, as a glance at the
two figures: (text figs. U, 19, 25) will show. It differs in size and proportions,
and particularly in the size and shape of the chromatophores. These Lemmer-
mann (1910) found were constant in his cultures and concluded that it formed
a valid species.

Amphidinium pacificum sp. nov.
Plate 2, figure 13; text figure U, 24

Dracnosis.—A large species with ellipsoidal body, its length 1.75 transdiam-
eters, girdle without displacement; sulcus extending from girdle to antapex;
pyrite yellow chromatophores. Length, 93. Pacifie off La Jolla, California,
July.

DerscripTION.—The body is ellipsoidal with broad, rounded apices, nearly circular in cross-
section, its length 1.75 transdiameters at the widest part. The epicone occupies a relatively
small part of the body, its distance from the apex on the dorsal face being only 0.03 of the total
length of the body. On the ventral face it extends posteriorly for about 0.49 of the total length
of the body, its sides forming an angle of about 60°. Its greatest transdiameter is about 0.14 of
the greatest transdiameter of the body. The hypocone is broad, slipper-shaped, widest in the
middle and flaring slightly immediately behind the girdle. The antapex is broad and rounded.

The girdle and sulcus meet at a point distant from the apex 0.49 of the total length of the
body. It turns anteriorly at an angle of 30° with the longitudinal plane of the body, for a short
distance, beyond which it steepens until near the margin it becomes subparallel with the main axis.
On the dorsal face it follows an almost transverse direction across the body, 0.03 of the total
length of the body from the apex, turning posteriorly on the right ventral face at an angle of
about 30° with the main axis and meeting the anterior end of the suleus without displacement.
The furrow is about 0.05 transdiameter in width, and deeply impressed, with smooth, slightly
undercut borders. The suleus extends from the girdle to the antapex as a narrow, somewhat
obscure furrow. The anterior flagellar pore is found at the junction of the two ends of the girdle.

The nucleus is a broadly ellipsoidal body on the right side of the middle part of the hypocone.
Its major and minor axes are about 0.47 and 0.34 transdiameters in length respectively.

A small sacklike pusule opens into the anterior flagellar pore. The cytoplasm is finely
granular and is filled with large alveoli. Near the anterior flagellar pore is a group of minute,
dark green, refractive granules, mingled with which are a few blue green spherules. In the
peripheral zone are a few ellipsoidal, leaflike chromatophores, pyrite yellow in color. These are
most numerous along the lateral margins of the body and near the girdle.

Dimenstons.—Leneth, 934; transdiameter, 53; axes of nucleus, 25 and 18».
to) b] b] ’

OccURRENCE.—This was taken July 25, 1917, in a surface haul 11 miles off
La Jolla, California, in a surface temperature of 21°75 C,

150 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Comparisons.—This is the only one of the larger species of Amphidinium
which possesses the small leaflike chromatophores such as are found in A.
dentatum and A. galbanum (figs. U, 4, 29).

Amphidinium rotundatum Lohmann
Text figure U, 22

Amphidinium rotundatum Lohmann (1908), pp. 147, 199, 202, 254, 261, 324, table B, pl.
17, fig. 9; (1911), pp. 30, 31, fig. 12c, pl. 1, fig.5

A. rotundatum, Paulsen (1908), p. 95, fig. 129.

A. rotundatum, Herdman (19116), p. 71; (1911c), p. 38.

A. rotundatum, Schiller (1911), p. 31.

A. rotundatum, Mielek (1914), p. 20.

A. rotundatum, Ostenfeld (1913), p. 338.

A. rotundatum, Lemmermann (1910), p. 615.

Dr1aGNnosis.—A minute species with broadly ovoidal body, its length 1.2 trans-
diameters; epicone very minute; yellow chromatophores. Length, 12. Baltic
Sea off Kiel, Germany.

DescripTION.—The body is broadly top-shaped, the narrow neck and head formed by the
girdle and flat epicone tapering posteriorly to a blunt antapex. Its length is 1.2 transdiameters
at the widest part. The girdle is broad, about 0.25 transdiameters, and deeply constricts the
anterior part of the body to 0.5 of its width behind the girdle. Sulcus not known. The flat
epicone also has a width of 0.5 transdiameter and no appreciable length. The most striking thing
about this organism is the yellow, leaflike chromatophores located in the peripheral layer of the
cytoplasm.

Dimenstons.—Length, 12; transdiameter, 10.

OccURRENCE.—Figured by Lohmann (1908) from the Baltic Sea off Kiel,
Germany, present throughout the year. Mielck (1914) records its presence in
the Barents Sea and White Sea near Kola, Russia, in June and July.

Amphidinium scissum sp. nov.
Plate 2, figure 22; text figure U, 1

Dracnosts.—A small species with ovate body, compressed dorsoventrally to
0.5 transdiameter, wider posteriorly; epicone flattened, higher at the right;
hypocone deeply notched at antapex; girdle displaced posteriorly 0.24 trans-
diameter; sulcus runs from apex to antapex; color greenish; food inclusions
often present; littoral habitat. Length, 564. Pacific at La Jolla, California,
July.

DeESCRIPTION.—The body is ovate, its greatest transverse diameter 1.7 to 1.8 transdiameters
at its widest part, which is slightly below the middle, compressed dorsoventrally to little less than
0.5 the greatest transdiameter. Its length is about 3 transdiameters measured in the girdle. The

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 151

length of the epicone is about 0.16 of the total length, measured from the proximal end of the
girdle ; its transdiameter, measured on the anterior lip of the girdle, is about 0.6 the greatest trans-
diameter of the hypocone, and its dorsoventral diameter about 0.33 of the same. The apex is
flattened and slopes to the right at an angle of 15° to 17° from the horizontal. It is traversed
by the sulcus, which crosses the apex and swings around to the left, encircling a small terminal
button, somewhat as in some species of Pouchetia. The hypocone is broadly ellipsoidal, its greatest
length, on its left shoulder, about 1.5 its greatest diameter, which is located about mid-
way between girdle and antapex. Dorsoventrally it is widest at 0.33 of its length from the
antapex, expanding gradually from the girdle, where its dorsoventral diameter is 0.66 of the
diameter at its widest part, and contracting at the antapex to an almost hemispherical outline in
lateral view, broken, however, by the deep semicircular noteh at the posterior end of the suleus.
This notch is about three times the width and depth of the girdle. It lies a little to the right of
the main axis and the left margin is the larger and longer one.

The girdle forms a descending left spiral, deepest at its ends, both of which are sharply
deflected posteriorly at angles of 30° and 45° respectively at the proximal and distal regions.
The distal displacement posteriorly is about twice the width of the girdle. There is no over-
hang. The furrow is deeply impressed with broadly rounded lips. The transverse flagellum
completely encircles the body.

The sulcus runs the whole length of the body, terminates anteriorly in a sinistral loop around
an apical button, has a sight sigmoid curve at the girdle and flares posteriorly in the antapical
notch. A ventral lobe on the right side at the posterior end pushes it somewhat to the left. The
longitudinal flagellum extends from the flagellar pore near the posterior end of the suleus
posteriorly beyond the antapex for a distance equal to the length of the body.

The surface is minutely and faintly striate with equidistant, parallel, longitudinal lines, about
eighteen across the dorsal face. They show faintly on the epicone, but more clearly on the
hypocone.

The cell contents consist of the posteriorly located ellipsoidal nucleus and numerous peripheral
greenish spherules of high refractive index, probably fatty products of metabolism. No definite
chromatophores could be detected. The whole body has a pale, sea foam green tone, due in part
at least to the refractive bodies. All inclusions in the form of yellowish spheres, red, and orange
spherules in different individuals are indications of the holozoie nutrition of this organism.

Luminescence not observed.

Dimenstons.—Length of body, 56“; transdiameter in girdle, 20/; at widest
part, 324; dorsoventral, 18+.

OccuRRENCE.—Taken frequently in washings from beach sand on ocean shore
at La Jolla, California, in July, 1914.

Comparisons.—This species is referred to Amphidinium rather than Gymno-
dinium because of its reduced epicone, deeply incised sulcus, and dorsoventral
compression. The large size of the epicone allies it with Gymnodinium, but
this feature is shared with Amphidinium asymmetricum, A. sulcatum, A. corpu-
lentum and to some extent with A. truncatwm (figs. U, 5, 10, 6,3). The extension
of the sulcus upon the epicone is also a feature of A. corpulentum and A. sul-
catum. Linear striae have been recorded in Amphidinium only on this species
and A. asymmetricum and A. truncatum.

152 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Amphidinium steini Lemmermann
Text figure U, 28

Amphidinium operculatum Stein (1883), p. 16, pl. 17, figs. 7-20.

A. operculatum, Pouchet (1883), p. 427; (1885a), pp. 32, 50, 51, 53, 54, 82, 83, 86, pl. 2,
fig. 9.

A. operculatum, Biitschli (1885), pp. 958, 967, 968, 1026.

A. operculatum, Schiitt (1896), p. 4, fig. 4

A. operculatum, Schréder (1900), p. 13.

A. operculatum, Lemmermann (1902), p. 260; as Amphidinium steinii, (1910), pp. 580,

616, figs. 1-7.

Dracnosts.—A small species with asymmetrical ovoidal, dorsoventrally com-
pressed body. its length 1.73 transdiameters; girdle anterior, without displace-
ment; sulcus extending from girdle to antapex; brown chromatophores. Length,
45 (?). Brackish waters, Wismar, Germany.

DerscrIpTion.—The body is asymmetrical, broadly ovoidal in ventral view, widest anteriorly,
dorsoventrally compressed with the vende al side convex and the dorsal convex anteriorly, but
coneave posteriorly. Its length is 1.73 transdiameters at the widest part and its dorsoventral
diameter 0.63 transdiameter. The epicone is a minute, caplike portion, separated from the rest
of the body by the wide girdle which abruptly constricts the anterior part of the body. Its
length is 0.16 that of the hypocone and its width 0.38 transdiameter. It is almost cireular in
outline, slightly rounded, and obliquely placed on the body so that the left dorsal side is much
higher than the right ventral side. The greater convexity of the right and ventral sides of the
body throws the epicone and girdle somewhat to the left and dorsal of the main axis. The
hypocone is long heart-shaped in ventral view, asymmetrical with the right side more convex than
the left, and with rounded antapex.

The girdle is placed far anteriorly and forms a complete circle about 0.3 transdiameter in
width. It deeply constricts the anterior part of the body, which, on its distal border, forms wide,
squarish shoulders, with the proximal border narrow and smoothly rounded. Dorsad its distance
from the apex is about 0.05, and ventrad 0.16 of the total length of the body. On the ventral
face of the body it merges into the wide V-shaped anterior end of the sulcus. The suleus narrows
to a slender line posteriorly and terminates without suleal notch near the antapex, and is usually
defiected slightly to the left near its posterior end. The longitudinal flagellum arises at the
junction of the girdle and suleus.

The nucleus is a small, spherical body found in the posterior half of the hypocone. Its axis
is about 0.34 transdiameter. At the junction of girdle and sulcus is a small, spherical pusule,
probably connected with the flagellar pore. In the central part of the cytoplasm is a small,
spheroidal amyloid (?) body and radially arranged around this are small stout rod-shaped brown
chromatophores. Three individuals showing the presence of ingested food bodies are figured by
Stein (1883, pl. 17, figs. 14-16. The chromatophores in these are smaller than in his figures
12 and 13. This would lead to the conclusion that nutrition may be either holozoie or holophytie
in this species.

Drvrenstons.—These are only approximate, as Stein (1883) gives neither
dimensions nor exact magnifications for his figures. Length, 45; transdiameter,
26; axis of nucleus, 9z.

OccURRENCE.—Figured by Stein (1883) from brackish water near Wismar,
Germany.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA \s3

SynonyMy.—This was originally figured by Stein (1883) as Amphidiniwm
operculatum Clap. and Lach. and separated as A. operculatum var. steini by
Lemmermann (1910).

Amphidinium sulcatum Kofoid
Text figures U, 10, 26

Amphidinium sulcatum Kofoid (1907a), pp. 299, 300, pl. 22, figs. 1-3.
A. sulcatum, Lemmermann (1910), p. 615.

A. sulcatum, West (1916), p. 52, fig. 37.

A. sulcatum, Herdman (1911b), p. 72; (1911c), p. 39.

Dracnosis.—A rather large, laterally compressed species, its length 1.7 trans-
diameters; girdle anterior; sulcus extending from apex to antapex; small vellow
chromatophores. Length, 68. Pacific off San Diego, June.

Description.—The body is laterally compressed, broadly oval in lateral view, ellipsoidal in
ventral view. Its length is 1.7 transdiameters, the dorsoventral diameter 1.4 transdiameters at
the widest part. The greatest width of the body is midway between the girdle and antapex. The
epicone is minute compared with the hypocone, its length being 0.14 of the total length of the
body. It is highest laterally and dorsally and hollowed out towards the suleus, which passes
dorsally beyond the apex. The hypocone is broadly rounded posteriorly, and very deeply
channeled ventrally by the suleus, which deepens as it passes posteriorly from the flagellar pore.

The girdle is anterior in position, slightly enlarged on the left side and narrowed at its distal
end, which is displaced posteriorly by about the width of the proximal end of the furrow. The
furrow is very deeply imbedded and its proximal width is more than twice that of the distal
region. The sulcus extends from the dorsal half of the epicone to the antapex. It is a narrow
channel anteriorly with a depth at the flagellar pore of 0.25 of the dorsoventral diameter at that
level and deepens posteriorly until at the antapex it reaches nearly 0.5 of the dorsoventral
diameter. The right lip of the furrow is somewhat higher than the left.

The surface is covered with a thin hyaline membrane. The nucleus is a spheroidal body in
the middle of the hypocone. It is filled with. moniliform chromatin strands and two polar
centrosomes (?) or nucleoli sunk in its substance. A pyriform vacuole les near the flagellar
pore, but its connection with the opening is not evident. A large amyloid body is present near
the nucleus and surrounding it are small angular yellowish chromatophores. The eytoplasm is
dense and coarsely granular.

Dimenstons.—Leneth, 684; transdiameter, 35; dorsoventral diameter, 55;
diameter of nucleus, 15.

OccURRENCE.—T'aken in a vertical haul of 165 meters to the surface, 10.5
miles off San Diego, California, June 14, 1904.

Comparisons.—This species stands alone among the species of Amphidinium
in having a laterally compressed body. It is, however, tentatively placed with
the dorsoventrally compressed forms in the subgenus Aimphidinium. Possibly
a separate subgenus should be established for the species. The truneate anterior
end recalls the condition in A. herdmani and A. truncatum.

154 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Amphidinium truncatum sp. nov.
Text figure U, 3

D1aGnosts.—A small species with sacklike body, its length 1.2 transdiameter,
dorsoventrally compressed to 0.5 transdiameter ; epicone low, squarely truncate,
left antapex pointed; sulcus confined to striate hypocone; pale green; littoral
habitat. Length, 384. Pacific at La Jolla, California, July, August.

Description.—The body is stout, its length 1.2 transdiameter, dorsoventrally compressed to
0.5 transdiameter. The epicone is 0.2 of the total length in height, and squarely truncate. Its
form above the girdle is that of a very low, truncate, ellipsoidal cone, whose major and minor
axes in its base are respectively 0.67 and 0.33 transdiameter and truncate apex 0.50 and 0.25
respectively. Its short side has a slope of about 40°. There is a noticeable suppression of the
asymmetry of the epicone so characteristic of A. asymmetricum and A. operculatum. The
hypocone is rotund, its length 0.8 of the total length and about equal to its greatest transdiameter
which is located near the middle. Its left side is less convex than the right and it shares with
the epicone the considerable dorsoventral compression. Anteriorly it spreads abruptly below
the girdle in a squarish shoulder, thereby increasing the width (transversely) at that level 25
per cent more than that of the epicone. The antapex is broadly rounded with a low symmetrical
rounded part on the right side of the deeply excavated posteriorly flaring sulcus, and a sharp
point on the left which projects less than a furrow’s width beyond the general contour.

The girdle is symmetrical, located 0.12 of the length below the apex. Its course is nearly
horizontal except at its proximal and distal ends which form an almost symmetrical V-shaped
junction on the ventral face about as long as the epicone. The furrow is broad, 0.12 trans-
diameter, and shallow. The sulcus is confined in the hypocone, is about two-thirds the width of
the girdle, has a very slight sigmoid curvature and widens posteriorly to 0.2 transdiameter. It
is deeply excavated to the middle of the body posteriorly at a point just below the junction of
the ends of the girdle. It has no flap on its left side, but is open throughout its course. Both
margins are continued beyond the antapex in a short projecting, more or less pointed tooth, the
left being the longer. The longitudinal flagellum arises from a pore at the proximal end of the
suleus, just behind the anterior flagellar pore. It extends posteriorly beyond the body for 0.83
of the total length.

The surface is uniformly striated on the hypocone with equidistant, parallel faint lines, about
twenty across the dorsal face. No lines can be detected on the short slopes of the epicone. The
peripheral pellicle surrounding the body is very distinct. The nucleus is an ellipsoidal, sub-
reniform body located in the left posterior part of the hypocone with its long axes passing from
the left anteriorly, to the right posteriorly. It is a little more than 0.5 of the transdiameter in
length, its minor axis is a trifle more than 0.5 of the major, and it shares in the general dorso-
ventral compression. A large pusule opens into the anterior flagellar pore and is connected by
a narrow canal with a smaller, circular pusule farther posterior and on the right side of the
body. A halo of subspheroidal, bluish green chromatophores fills the peripheral layer of
cytoplasm. The general color is a diffuse pale pea green.

Dimenstons.—Total length, 38; greatest transdiameter, 30+; dorsoventral
diameter, 15.

OccURRENCE.—Very abundant in the beach sand off La Jolla, California,
during July, 1914. It lives in laboratory aquaria for two to three days, but
becomes inactive very quickly when exposed to the illumination of the
microscope.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 155

ComPparisons.—The flattened epicone of this species suggests those of A.
operculatum, A. scissum, and A. herdmani (figs. U, 25, 1, 2), the last having the
greatest resemblance. It is quite distinct from these species, however, in the
form of epicone, the well developed pellicle, proportions of the body, and the
striate hypocone.

Amphidinium turbo sp. noy.
Plate 9, figure 98; text figure U, 16

Dracnosis.—A minute species with broadly ovoidal body; length 1.58 trans-
diameters, apex and antapex subacute; girdle anterior without displacement ;
sulcus very short; color pearl grey. Length, 23H. Pacific off La Jolla, Cali-
fornia, July.

DescripTion.—The body is broadly ovoidal, widest in front of the middle part of the body,
its length 1.38 transdiameters at the widest part. The epicone is a minute peaked, caplike portion
surmounting the broad girdle. It has a length of 0.13 of the total length of the body. It is
broadly conical in shape, forming an angle of about 110°, with the apex excentrically placed
slightly to the left. The hypocone is cordate-shaped in ventral view and symmetrically rounded,
with slight tendency to a subacute point at the antapex.

The girdle is broad, about 0.15 transdiameter and deeply impressed. It is placed far
anteriorly and the transdiameter in it is about 0.4 of the broadest transdiameter of the body.
It forms a complete circle around the body. The anterior flagellar pore is located near the
posterior border of the girdle at the left of the median line. The posterior pore is located about
one width of the girdle below the anterior one. The sulcus is a short V-shaped depression below
the anterior flagellar pore. Its length is nearly twice the diameter at the girdle.

The large, spheroidal nucleus is found in the central part of the body. Coarse moniliform
chromatin strands, eight across one face, are prominent in its structure. Its axis is about 0.5
transdiameter in length.

The cytoplasm is very clear and transparent without apparent granulations. Its color is
pearl grey. The pellicle of the hypocone appears as a double-contoured line. The eytoplasm
contains numerous, blue green spherules and more minute granules. The epicone appears to be
destitute of these. No striations or other markings could be detected on the surface.

Divensions.—Length, 23; transdiameter, 17; axis of nucleus, 9v.

OccURRENCE.—Two individuals were observed in the collections made in the
Pacific off La Jolla, California, in 1917. These were taken July 5, with a No. 12
silk net, in a haul 6 miles off La Jolla, from 80 meters to the surface and in a
surface temperature of 21°9 C. On July 25 another was noted in a haul made
11 miles offshore, from 80 meters to the surface and in a surface temperature
of 21°7 C.

Comparisons.—This form shows a strong resemblance to A. lacustre Stein.
Stein’s (1883) species is found in fresh and brackish waters and possesses
brownish chromatophores. It may be that our form is the marine representative
of the same species.

156 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Amphidinium vasculum sp. noy.
Text figure U, 27

Dracnosts.—A rather large species with subcuneiform body, its length 1.54
transdiameters; girdle without displacement; sulcus short on epicone, reaching
antapex on hypocone; color, bright green mixed with pink and yellow orange.
Length, 94", Pacific, off La Jolla, California, August.

DeEscripTion.—The body is rotund, subeuneiform, broadly rounded posteriorly, conical an-
teriorly, where is also its widest part; its length is 1.54 transdiameters at the widest part. A
cross-section of the body is nearly circular in outline. The epicone occupies a relatively small
part of the body. Viewed from the ventral face it is rhomboidal in shape, with its greatest
length equal to 0.4 of the total length of the body. Dorsad, the length of the epicone is 0.13 of
the total length. Its general shape is that of a broad, flat cone of 122° with blunt apex, and
nearly straight sides. The hypocone is elongate cylindrical, flaring somewhat anteriorly and
broad, smoothly rounded posteriorly, a trifle longer at the left.

The girdle joins the suleus at a distance from the apex of 0.4 of the total length of the body.
It immediately turns anteriorly at an angle of about 50° with the longitudinal axis of the body,
with a slight irregularity in its course, until it reaches the dorsal side of the body, which it
traverses in an almost transverse direction at a distance from the apex of 0.13 of the total length
of the body. On the right side of the ventral face it again turns posteriorly at an angle of 55°
and meets the opposite end of the suleus without displacement. The furrow is wide, about 0.05
transdiameter, and deeply impressed, undereutting its anterior border and curving gradually
outward posteriorly. Both lips are smooth and flare slightly beyond the surface of the body.
The suleus begins about midway between its junction with the girdle and the apex and extends
posteriorly to the antapex. Its course on the epicone is at an angle of about 25° with the longi-
tudinal axis of the body. Beyond the girdle its course is that of a straight line to the posterior
margin of the body. Posterior to the anterior flagellar pore it becomes slightly narrower than
on the epicone, broadening at its posterior extremity. The anterior flagellar pore is located at
the junction of the girdle and sulcus, the posterior pore about midway between that and the
antapex.

The nucleus is a rather large ovoidal body lying slightly posterior to the central part of the
hypocone. Its axis is about 0.44 transdiameter in length. A small sacklike pusule opens into
each flagellar pore. The cytoplasm is finely granular and shows a distinct line of ectoplasm
around the margin of the body. This is clear and devoid of alveoli or other markings. In the
central part of the cytoplasm, slightly posterior to the anterior flagellar pore, is a dark, spheroidal
body, ventrad to which is a group of minute, bright green refractive granules. These immedi-
ately surround the anterior flagellar pore and its communicating pusule. Radiating out from
this center are a number of long, blue green rodlets or canals. Near both apices are groups of
large, salmon pink vacuoles. A few blue green oil droplets and one large, olive green body and
one of yellow ochre near the midregion complete the list of cytoplasmic inclusions. The general
color is bright green mixed with pearl grey, pink and yellow orange. No striae or other surface
markings could be detected.

Dimensions.—Length, 94; transdiameter, 61; axis of nucleus, 28+.

OccuRRENCE.—This was found August 6, 1917, in a haul 4 miles off La Jolla,
California, with a No. 25 net, from 60 meters to the surface and in a surface
temperature of 21°2 C. It was observed again on August 13, in a haul 0.75 mile
offshore and from 83 meters to the surface.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA By

CoMPARISONS.—This species greatly resembles Gymnodinium amphora. The
relative proportions of epicone and hypocone, however, tend to rank it with
Amphidinium, though on rather arbitrary grounds. It and A. cucurbita are
the most highly specialized members of the genus and of a type closely paral-
leling the highest specialization of the genus Gymnodinium. The ectoplasmic
structure in A. vasculum lacks the high degree of development found in many
of the species of the subgenus Pachydinium in Gymnodinium, but is clearly of
a similar nature. In its cytoplasmic structure it resembles A. cucurbita and
Gymnodinium dogieli and G. pachydermatum. In coloring it is one of the most
striking species of the genus.

CHAPTER XI

GYMNODINIIDAE: GYMNODINIUM, G. ABBREVIATUM TO
G. GRAMMATICUM

GYMNODINIUM Stein emend.
Text figures A, B, I, M, V-BB
Gymnodinium Stein (1878-83), in part, pp. 89-91, pl. 2, figs. 14-21, pl. 3, figs. 1-4.
Peridinium Ehrenberg (1834), in part, pp. 126-127; (1835), pp. 270-271; (1838), p. 254,
pl. 22, fig. 15.
Gymnodinium, Saville-Kent (1880-82), pp. 442-444, pl. 25, figs. 17-20, 53, 54, 58-61.
Gymnodinium, Pouchet (1883), in part, pp. 445, 446, text figs. I, L, M, pl. 21, figs. 39, 40.
Gymnodinium, Biitschli (1885), in part, pp. 1007, 1008, pl. 51, figs. 4-9.
Gymnodinium, Schiitt (1895), in part, pls. 21-25; (1896), pp. 4, 5, fig. 5.
Gymnodinium, Delage and Hérouard (1896), in part, p. 384. Fig. 666 is Gyrodinium
spirale.
Gymnodinium, Mez (1898), in part, p. 216.
Gymnodinium, Schoénichen and Kalberlah (1900), p. 230; (1908), p. 251.
Gymnodinium, Calkins (1902), in part, p. 429, fig. 20.
Gymnodinium, Paulsen (1908), in part, pp. 97-101, figs. 132-138.
Gymnodinium, Lemmermann (1910), p. 565, figs. 13, 14, 17-23; p. 613, figs. 1-19, 23, 26,
30; pp. 618-626.
Gymnodinium, Doflem (1911), in part, pp. 526-529, figs. 472-475.
Gymnodinium, Poche (1913), pp. 162, 163.
Gymnodinium, Schilling (1913), pp. 14-21, figs. 10-20.

DIAGNOSIS

Gymnodiniidae without torsion of the body; girdle a descending left spiral
displaced less than one-fifth the total length of the body or it may form a com-
plete circle around the body; sulcus may extend from the apex to the antapex
or may be very short on either epicone or hypocone or both. The nucleus is
usually in the center or posterior part of the body, but. is sometimes found
anteriorly; perinuclear membrane rarely present; nucleus usually filled with
distinct moniliform chromatin strands. Pusules are generally found, opening
anteriorly into the anterior flagellar pore, posteriorly into the posterior pore,
or rarely they may be fused into one large pusule opening into both pores. No
nematocysts; plasma varying from colorless, with or without chromatophores,
to highly colored; pigment granules sometimes present. Surface may be
smooth, striate, ridged, or furrowed. Sometimes differentiated into ectoplasm
and endoplasm. Nutrition may be holozoic or holophytic. Eneystment in thin-
walled membrane frequent. Length, 11-210. Marine, brackish, and fresh
waters, pelagic and littoral, mainly in temperate latitudes; 76 species known.

[158]

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 159

ORGANOLOGY

Gymnodinium stands next to Amphidinium in its organology, differing
mainly from that genus and from Gyrodinium in the position and arrangement
of girdle and sulcus. The epicone occupies a relatively greater proportion of
the body than in Amphidinium, the girdle being placed nearer the center of the
body (fig. V). A few species, as for example G. amphora (fig. AA, 6), approach
the Amphidinium type. The girdle PX
may form a complete circle around Ate atesen poe. Sena rod.
the body, as in G. lineopunicum (fig.
X, 17), or the ends may be displaced
from a very slight amount up to \ ;
nearly 0.2 of the total length of the =~ ~~ | a: ~ Neeser te
body. <A displacement as great as
this is rare, G. rubrum alone showing
it (fig. Y, 4). When so displaced

the girdle approaches the Gyrodiniwm ref. gr.
type. It is usually submedian or eee Ait!
slightly anterior in position. Three
species only exhibit, in a noticeable _.— hyp.
degree, a location of the girdle pos-
terior to the equator or middle of the SIRE
body, G. dissimile, G. musei, and G.
vorticella (figs. X, 32, 3, 29). |

The suleus is usually well devel- Osseo ase ieee
oped, without torsion or with only a
very shght amount, as in G. rubrum. +

It usually extends from or near the Tie Ve GT RD CARN Ge aOR Ne
apex to the antapex in a more or less __ tions: ant. p., anterior flagellar pore; ect., ectoplasm;
‘ . 5 4 epi., epicone; gir., girdle; hyp., hypocone; long. fl., longi-
sinuous line. It is shallow anteriorly, tudinal flagellum; n., nucleus; post. p., posterior pore;
generally, deepening, ostertorly,.ats | fu Siteas! wr fl, transverse degellum; vac, vacuole
greater development in the latter re- * °°°
spect being reached in G. bifurcatum, where the suleus bifurcates nearly the
entire length of the hypocone (fig. AA, 3). Its borders are not so protuberant
as in Amphidinium, yet are apparently capable of great distension, as shown by
the size of the food bodies sometimes ingested (pl. 6, fig. 65).

The position of the nucleus is not constant, but it may be found in any part
of the body. This sometimes happens within the species, as in G. heterostriatum,
as a result of the ingestion of large food masses which displace the existing cell
contents. In the greater number of species it is found in the central or posterior
parts of the body. It usually has distinct, beaded chromatin threads. One
species only, G. rubrum (pl. 8, fig. 86), shows a well developed, perinuclear
membrane. This is similar in its structure to that found in Gyrodinium coral-
linum (pl. 10, fig. 117). It is noteworthy also that this species stands nearest
to Gyrodinium in its type of girdle arrangement.

160 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

In cytoplasmic differentiation, as distinct from the organelles contained
within it, the genus Gymnodinium exhibits both the simplest as well as the most
advanced conditions found within the Gymnodiniidae, if not indeed within the
Gymnodinioidae. The simplest type is shown in G. minor with its minute proto-
plasmic body surrounded by a thin periplast (fig. X, 12). The most advanced
type is that found in @. dogieli, with its thickened ectoplasm consisting of two
distinct layers completely surrounding the body and its distinct groups of
vacuoles, refractive bodies and radial rodlets, and its well developed pusules
(fig. V). Its ectoplasm resembles that in many of the ciliates, the alveolar layer,
however, being at the surface of the body instead of separated from it by a
layer as is usual with the Ciliata. The superficial location of the alveoli gives
a bossed surface to these organisms which is very characteristic.

Fig. W. 1,2. Gymnodinium lira sp. nov. X 477. 1. External form only, showing the ridges of the body.
2. Optical section of hypocone showing the structure of the cytoplasm. Note vacuoles surrounding nucleus
and the food body. 3. Amphidinium cucurbita sp. nov. X 500. Superficial structure of the body only, showing
the furrows and striations of the surface.

The surface of the body in Gymnodinium presents nearly all the modifica-
tions found within the Gymnodinioidae. In the subgenus Gymnodinium,
containing the primitive or more generalized species, surface striae or other
markings are relatively rare (fig. X). One species in that group, G. herbaceum
(fig. Y, 17), shows a few, rather widely separated striae on the hypocone only;
G. sulcatum has the hypocone marked by a few furrows, and G. contractum the
same markings on the epicone. In the subgenus Lineadinium (fig. Y) each
species shows a typical and fairly constant striate surface. The striae may
be distinct lines or linear series of short rodlets, and usually vary somewhat in
number on epicone and hypocone. In all the species carefully observed these
striae are blue green, as are also those in the next subgenus. When pigment
is present it is found to collect along the surface striae as in G. rubrum (pl. 8,
fig. 85). This is a condition more frequently met with, however, in Gyrodinium.

Fig. X. Gymnodinium, subgenus Gymnodinium subgen. nov. 1. G. sulcatum sp. nov. 2. G. contractum

sp. no. 3. G. musei Danysz. After Pouchet (1887, pl. 10, fig. 6). 4. G. rubricauda sp. nov. 5. G. fusus Schiitt.
After Schiitt (1895, pl. 24, fig. 79). 6. G. scopulosum sp. nov. 7. G. flavum sp. nov. 8. G. rotundatum Klebs.
After Klebs (1912, p. 392, fig. 5). 9. G. wberrimum (Allman) Kofoid and Swezy. After Penard (1891, pl. 5,
fig. 8). 10. G. bogoriense Klebs. After Klebs (1912, fig. 7). 11. G. violescens sp. nov. 12. G. minor Lebour.
After Lebour (1917), fig. 8). 13. G. marinwm Saville-Kent. After Saville-Kent (1880-82, pl. 25, fig. 60).
14. G. biciliatum Ohno. After Ohno (1911, pl. 1, fig. 4). 15. G. ovulum sp. nov. 16. G. palustre Schilling.
After Schilling (1891a, pl. 10, fig. 11). 17. G. lineopunicum sp. nov. 18. G. mirabile Penard. After Penard
(1891. pl. 5, fig. 1). 19. G. fuseum (Ehrenberg) Stein. After Ehrenberg (1838, pl. 22, fig. 15). 20. G. filum
Lebour. After Lebour (1917), fig. 9). 21. G. ravenescens sp. nov. 22. G. grammaticum Pouchet. After Pouchet
(1887, pl. 10, fig. 8). 23. G. varians Maskell. After Maskell (1887, pl. 1, fig. 9). 24. G. viride Penard. After
Penard (1891, pl. 4, fig. 11). 25. G@. aeruginoswm Schilling. After Schilling (1891a, pl. 10, fig. 10). 26. G.
paradozum Schilling. After Schilling (1891a, pl. 10, fig. 13). 27. G. conicwm Lebour. After Lebour (1917b,
fig. 4). 28. G. cinctum sp. nov. 29. G. vorticella Stein. After Stein (1883, pl. 3, fig. 1). 30. G. fulgens nom.
sp. nov. After Lebour (1917), fig. 3). 31. G. doma sp. nov. 32. G. dissimile sp. nov. 33. G. inciswm sp. nov.
34, G. carinatum Schilling. After Schilling (1891la, pl. 10, fig. 12). 35. G. pseudonoctiluca Pouchet. After

Pouchet (1885a, pl. 4, fig. 34). 500.

162 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

In the subgenus Pachydinium (figs. Z, AA), containing the most highly
differentiated species of the genus, striae, furrows and ridges are found, as well
as a pellicle devoid of such surface markings. Most of the species with the
latter condition have an uneven surface contour, due to the well developed
alveolar layer, the component parts of which are rounded outwardly, as in G.
pachydermatum (fig. AA, 5). Many of the species exhibit a marked radial
arrangement of the metaplasmic products. Two species, G. abbreviatum (pl. 6,
fig. 63) and G. situla (pl. 1, fig. 12), have striae in addition to this noticeable
unevenness of surface. G. lira has the surface marked by high ridges (fig. W, 1).

The genus Gymnodinium shows a range of coloring remarkable for its
diversity and brilliancy. While nearly all the colors of the spectrum are rep-
resented, the predominating one is vellow, with its various shades and tones.
The coloring may be confined to chromatophores, as in many of the species in
the subgenus Gymnodinium sensu strictu, or diffused throughout the cytoplasm,
as in most of the other species. In G. lineopunicum (pl. 6, fig. 65) the pome-
eranate purple pigment is aggregated into oblong masses and a coarse network,
which constantly changes in outline and position. In G. violescens (pl. 6, fig.
69) the amaranth purple pigment is collected into small disks thickly scattered
through the peripheral layer. The pigment is very frequently collected at
the apices, particularly when aggregated into masses. In some species, as G.
pachydermatum and G. dogieli (pl. 3, figs. 32, 34), the color is largely confined
to the peripheral layers of cytoplasm, and is usually densest near the apices or
at the girdle. In other species it is diffused uniformly throughout the body,
as in G. situla (pl. 1, fig. 12).

In the more generalized species in the subgenus Gymnodinium sensu strictu
the predominating colors are yellow, vellow ochre, and green. This group is
made up largely of those species possessing chromatophores. The six species
showing the greatest variation from this color scheme, to wit, G. violescens
(pl. 6, fig. 69), G. Lneopunicum (pl. 6, fig. 65), G. sulcatum (pl. 8, fig. 83), G.
rubricauda (pl. 8, fig. 88), and G. contractum (pl. 5, fig. 52), while exhibiting
colors which are not found elsewhere in the genus, with two exceptions, do not
present a greater complexity of structure beyond that inherent in the color
itself, as in G. lineopunicum. Two species, G. rubrum (pl. 8, fig. 86) and G.
lineutum (pl. 1, fig. 2) mm the subgenus Lineadiniwm, have the same rose red
color found in G. sulcatwm. These species show a shght advance, however, as
one at least, G. rubrwm, evidently forms one of the connecting links between
Gymnodinium and Gyrodinium. The predominating colors in the subgenus
Lineadinium are yellow and green, with blue in G. translucens (pl. 2, fig. 17)
and neutral tints in G. multilineatum (pl. 5, fig. 59). In the subgenus Pachy-
dinium the colors are diversified, vet here, too, yellow orange is conspicuous.
The most highly differentiated species, G. pachydermatum, G. dogieli, and G.
amphora (pl. 3), have this color, vet G. abbreviatum (pl. 6, fig. 63), with also a
high degree of specialization, is pink in color. Gymnodinium puniceum, with

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 163

its onion-skin pink, is totally unlike the colors found elsewhere in the Gymno-
diniidae (pl. 3, fig. 51). Gymnodinium coeruleum is one of the few species
showing a clear blue color. Other species sometimes show a faint bluish tinge,
as occasionally in G@. gracile and G. canus. It is noteworthy here that those
species having colored pigment aggregated into clumps have the shades of red,
purple, and violet found in Gyrodinium and in some of the most highly special-
ized forms in Cochlodinium, Pouchetia, and Erythropsis. These colors are
found in the most generalized group of the genus Gymnodinium. On the other
hand the rich orange yellow found in the most highly specialized members of
that genus is entirely lacking in Hrythropsis and Pouchetia and nearly so in
Cochlodinitum. The line of development, in so far as determined by the color,
leads onward from the more generalized species of the genus and not from its
most highly specialized ones.

The species of this genus are in part holophytic and in part holozoic. The
predominant type of nutrition in the more generalized subgenus Gymnodinium
is holophytic. the majority of species in that group possessing chromatophores,
yellow, vellow ochre, and green in color. In some of these forms, however, the
possibility of holozoic nutrition, even when chromatophores are present, is not
altogether excluded, as shown by the presence of foreign bodies in the cytoplasm,
as in G. agile (fig. Y, 9), G. herbacewm (fig. Y, 17), G. ravenescens (fig. X, 21),
and G. flavum (fig. X, 7). This condition is similar to that in Amphidinium
steint (Stein, 1883, pl. 17, figs. 14-16) and A. scisswm (pl. 2, fig. 22). In the
species G. fulgens (Lebour’s (1917b) G. pseudonoctiluca, our fig. X, 30) several
large bodies are present, but no intimation is given as to their nature. The
cytoplasm of G. herbaceum particularly is filled with the accumulated products
of metabolism in the form of oil droplets and green, blue, and grey vacuoles.

In the next two subgenera, Lineadiniwm and Pachydinium, nutrition is
probably largely, if not entirely, holozoic. In the first named group indisputable
evidence of this is found in one species only, G@. heterostriatum. The individuals
of this species observed under the microscope proved to be insatiable cannibals.
The actual process of ingestion was not observed, but very few specimens were
noted which did not contain large food masses. In many cases these were
recognizable as species of Gymnodinioidae (pl. 5, fig. 56). Their ejection from
a posterior vent in the body was often seen. In many of the other species the
cytoplasm usually contains oil droplets, vacuoles and refractive bodies, the
accumulations of the products of metabolism suggestive of holozoic nutrition.
These are especially striking in the subgenus Pachydinium. The body here is
frequently filled with large food masses, as in G. puniceum and G. sphaericum.
The sulcus in the midregion of the body probably functions as the mouth, and
the posterior part of the body, particularly the suleal notch, as the vent for
ejecting foreign particles and fecal masses.

Cyst formation is common in Gymnodinium, and the cyst generally takes
the form of a very thin, hyaline membrane. <A second or even third membrane

164 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

fo “al na
on On ye A

H)
pope

Fig. Y. Gymnodinium, subgenus Lineadinium subgen. nov. (in part). 1. G. multistriatum sp. nov. 2. G.
translucens sp. nov. 3. G. aureum sp. noy. 4. G. rubrum sp. nov. 5. G. hamulus sp. nov. 6. G. diploconus Schutt.
7. G. heterostriatum nom. sp. nov. 8. G. achromaticum Lebour. After Lebour (1917), fig. 5). 9. G. agile
sp. noy. 10. G. vestifici Schiitt. After Schiitt (1895, pl. 25, fig. 85). 11. G. helveticwm Penard. After Penard
(1891, pl. 5, fig. 10). 12. G. attenuatum sp. nov. 13. G. auratum sp. nov. 14. G. lineatum sp. nov. 15. G.
rhomboides Schiitt. After Schiitt (1895, pl. 21, fig. 63). 16. G. cuewmis Schitt. After Schutt (1895, pl. 24,
fig. 64). 17. G. herbaceum Kofoid. 18. G. multilineatum sp. nov. X 500.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 165

Fig. Z. Gymnodinium, subgenus Pachydinium subgen. nov. 1, 2. G. canus sp. nov. 1. Ventral view. 2.
Lateral view. 3. G. gracile Bergh. 4. G. coerulewm Dogiel. After Dogiel (1906, pl. 2, fig. 47). 5. G. punicewm
sp. noy. 6. G. situla sp. nov. 7. G. abbreviatum sp. noy. 8. G. wilezeki Pouchet. After Pouchet (1894, pl. 22,
fig. 1). 9. G. radiatum sp. nov. 10. G. costatum sp. nov 11. G. lira sp. nov. %X 500.

166 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

may be formed in succession, the outer usually large, as a result of distention,
the inner following the contour of the body very closely (pl. 5, fig. 53). This
inner membrane forms as a thin pellicle on the outer surface of the body and
is expanded by incoming fluid.

DisrripuTion.—The occurrence of Gymnodinium has been recorded mainly
from waters of temperate latitudes. Two species only, G. wilczeki and G.
pseudonoctiluca, were found by Pouchet in scant numbers in the Arctic Ocean
near Spitzbergen, July 31, 1892. One marine species has been recorded from
the tropics, G. fusus, by Karsten (1907) in the Indian Ocean at 2° 58’ 5 N,
46° 50’ 8 E. Klebs (1912) found three fresh-water species near Buitenzorg,
Java, G. aeruginosum, G. borgoriense, and G. varians.

Of the remainder, twenty are fresh-water forms. Of these the greater
number of species have been found in Switzerland as the result of the work of
the Swiss naturalist Penard. The following species are recorded from Lake
Geneva: G. helveticum, G. viride, and G. rufescens (G. uberrimum) by Penard
(1891), G. palustre by Guyer (1910); and from other waters in Switzerland,

r. carinatum, G. fuscum, and G. paradoxum by Schilling (1891a@), and G. aeru-

ginosum by Amberg (1900). The lakes and ponds in Germany have also proved
a fertile field, particularly the Lake Plon region. The species recorded here
are: G. paradoxum by Lemmermann (1903a); G. helveticum and G. tenwis-
simum by Lauterborn (1894, 1910) ; G. palustre by Schilling (1891a) ; G. fuscwm
by Apstein (1896) and others; G. zachariasi by Zacharias (1899); G. rotun-
datum by Klebs (1912); and G. aeruginosum by Marsson (1901). Allman
(1854, 1855) reported G. uberrimum (as Peridinium uberrima) from Dublin,
Ireland. West and West (1909a) found G. paradoxum in both the English
and Scottish lakes and G. zachariasi in the Irish lakes. From Austria-Hungary
Entz (1910) has recorded G. zachariasi and Stein (1878) G. vorticella and G.
aeruginosum. The latter species has also been recorded from the Finnish lakes,
with G. fuscum, by Levander (1894b, 1900). Gymnodinium fuscum was noted
in the Zealand and Jutland lakes in Denmark by Wesenberg-Lund (1904) and
in Brazil by Cunha (1913), who also recorded G. viride from the same place.
Butschinsky (1897) records G. aeruginosum from Odessa, Russia, and Bolo-
chonzew (1903) G. palustre from the Volga River. <A single record comes from
New Zealand of G. varians by Maskell (1887) and one of G@. biciliatum from
Japan by Ohno (1911). The species G. muset was noted at Paris, France, by
Pouchet (1887).

Of these fresh-water species G. fuscum and G. aeruginosum are the most
widely distributed. Unfortunately the location of the discovery of G. fusewm
in Brazil has not been given by Cunha (1913), so that no deductions can be
made in regard to its temperature relations.

Of the twenty marine species the larger number come from the Mediter-
ranean and the Atlantic. These are G@. cucumis, G. diploconus, G. fusus, G.
gleba, G. rhomboides, and G. vestifica, described by Schutt (1895). Unfortu-

KOFOID AND SWEZY: UNARMORED DINOPLAGELLATA 167

Fig AA. Gymnodinium, subgenus Pachydinium subgen. noy. Magnification 500, except where otherwise
stated. 1. G. dogieli sp. nov. X 350. Lateral view. 2. G. bifurcatum sp. nov. Lateral view. 3. G. bifurcatum
sp.nov. X 333. Ventral view. 4. G. gleba Schiitt. After Schiitt (1895, pl. 25, fig. 86). 5. G. pachydermatum
sp. noy. 6. G. amphora sp. nov. 7. G. tenuissimum Lauterborn. After Lauterborn (1894, pl. 2, fig. 26). 8. G.
dogieli sp. nov. 9. G. sphaericum Calkins.

168 MEMOIRS OF THE UNIVERSITY OF CALIFGR* [A

nately he neglected entirely to give the source of his material, but it is stated
by him (in litt.) to be in the greater part from the Gulf of Naples. Pouchet
(1887) deseribed G. grammaticum from the Atlantic off the coast of France;
Calkins (1902) found G. sphacricum (G. gracile var. sphaerica) off Woods
Hole, Mass., and Wright (1907) figures G. gracile from Nova Scotian waters.
From the waters of the North Sea, the Skager Rack and Cattegat, are recorded:
G. pyrocystis by Jorgensen (1912); G. rhomboides by Paulsen (1907) ; G. ves-
tifict by Lohmann (1908) and Ostenfeld (1913), and G. gracile by Ostenfeld
(1913). From the Mediterranean, particularly the Bay of Naples, come G.
heterostriatum, G. lunula, and G. coeruleum, recorded by Dogiel (1906), and
G. grammaticum, recorded by Schréder (1900). G. gracile is recorded by Bergh
from the Baltic Sea, as is also G. vestifici by Lohmann (1908). Of the remaining
records Lebour (1917b) gives G. minor, G. fulgens (G. pseudonoctiluca), G.
achromaticum, G. conicum (G. viridis), G. rhomboides, and G. filum from
Plymouth Sound, England, and Pouchet (1894) describes G. wilezeki from the
Arctie Ocean. Saville-Kent has described G. marinuwm from an infusion of hay
and sea water at St. Heliers, Isle of Jersey.

Thus far no species have been described from the Pacific Ocean. To these
twenty marine species we herewith add one new species, G. herbaceum Kofoid
MSS, from the Bay of Naples, and thirty-five new species from the Pacific
Ocean off the coast of California near San Diego, as follows: G. abbreviatum,
G. agile, G. amphora, G. attenuatum, G. auratum, G. aureum, G. bicorne, G.
bifurcatum, G. canus, G. cinctum, G. costatum, G. contractum, G. dissimile, G.
dogieli. G. doma, G. flavum, G. hamulus, G. incisum, G. lira, G. lineatum, G. line-
opunicum, G. multilineatum, G. multistriatum, G. ovulum, G. pachydermatum,
G. puniceum, G. radiatum, G. ravenescens, G. rubricauda, G. rubrum, G. scopu-
losum, G. situla, G. sulcatum, G. translucens, and G. violescens. In addition we
give new records for the occurrence of the following seven species in the Pacific
at San Diego: G. diploconus Schutt, G. gleba Schitt, G. gracile Bergh, G. hete-
rostriatum nom. sp. nov. (=G. obtusum Dogiel), G. lunula Schiitt, G. rhom-
boides Schiitt, G. sphaericum Calkins (= G. gracile var. sphaerica Calkins).

Prior to the establishment of Gymnodinium by Stein in 1878 the imperfec-
tion of our knowledge of the dinoflagellates in general, the lack of information
as to the relations of the armored and unarmored forms, the slight data on
encvstment and the misinterpretation of the transverse flagellum as a row of
cilia, all conspired to prevent the recognition of this genus and scatter its
representatives in other genera, often ill founded. Thus the first species be-
longing to it, G. fuscum, was described by Ehrenberg (1834) as Peridinium
fuscum. Later (1840) this same indefatigable explorer described very briefly
as Peridinium monas a species which Saville-Kent (1880-82) doubtfully refers
to his Gymnodinium marinum. The greatest synonymical confusion was created
by Diesing’s two attempts (1850, 1866) to reorganize the classification of hel-
minths, which at that time included many of the imperfectly known microscop-
ical forms of life. In his Systema Helminthum (1850) he included in his

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 169

new genus Heteraulacus Ehrenberg’s Peridinium fuscum and P. monas and
Schmarda’s (1846) P. adriaticum. He changed this generic name in his later
Revision der Prothelminthen (1866) to Heteroaulax and added thereto
Schmarda’s (1854) Peridiniwm inerme. Allman’s (1854) species uberrima was
placed by him in Peridinium, but was later made the type of Melodinium by
Saville-Kent (1880-82), but it clearly belongs to Gymnodinium, established in
1878 by Stein.

Fig. BB. Gymnodinium. 1. G. lohmanni (Paulsen). After Lohmann (1908, pl. 17, fig. 26). 2. G. triangu-
laris Lebour. After Lebour (1917), fig. 7). 3. G. zachariasi (Zach.) Lemm. After Zacharias (1899, fig. 4).
4, G. lachmanni Saville-Kent. After Saville-Kent (1880-82, pl. 25, fig. 59). 5. G@. lohmanni Paulsen. After
Lohmann (1908, pl. 17, fig. 25). 6. G. lachmanni Saville-Kent. After Saville-Kent (1880-82, pl. 25, fig. 58).
7. G. monadicum (Perty). After Perty (1852, pl. 7, fig. 15). 8. G. simplex (Lohm.). After Lohmann (1908,
pl. 17, fig. 17). 9. G. bicaudatwm Pavillard. After Pavillard (1905, pl. 3, fig. 5). 10. G. bicorne sp. nov. 11.
G. roseolum (Schm.). After Schmarda (1854, pl. 1, fig. 9). 12. G. lohmanni Paulsen. After Lohmann (1908,
pl. 17, fig. 28). 13. G. tintinnicola Lohmann. After Lohmann (1908, pl. 17, fig. 6). 14. G. corpusculum (Perty).
After Perty (1852, pl. 7, fig. 14). 15. G. inerme (Schm.). After Schmarda (1854, pl. 1, fig. 8). 16. G. rete -
Schitt. After Schiitt (1895, pl. 21, fig. 63). 17. G. gracile v. exiguwm Pouchet. After Pouchet (1883, pl. 21,
fig. 40). 18. G. punctatum Pouchet. After Pouchet (1887, pl. 10, fig. 7). 500.

170 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Historical Discussion

This genus was established by Stein (1878) for two species described by
Ehrenberg (1834, 1838) as Peridinium fuscum and P. pulvisculus. He con-
sidered this the basic type for the more complex Peridiniidae. Later (1883)
he changed Gymnodinium pulvisculus (Ehr.) to Glenodinium pulvisculus. He
also (1883) described Gymnodinium aeruginosum and G. vorticella and trans-
ferred to the genus Schmarda’s Glenodiniwm roseolunm as Gymnodinium
roscolum. His use of the species designation G. pulvisculus has proved a source
of some confusion in later literature. Klebs (1883) records, without figuring,
a form from fresh water as G. pulvisculus with a note that he is not certain of
its identity with Stein’s species, overlooking the fact that Stein had changed
that species to Glenodinium. Pouchet (1885) later gives the name G. pulvis-
culus to a Gymnodinium-like organism parasitic on Appendicularia. Lemmer-
mann (1899) reserves the name G. pulvisculus for Kleb’s form and gives to
Pouchet’s parasitic organism the name G. poucheti. Chatton (1906) notices the
close relation of Pouchet’s species with his newly created genus Blastodinium,
changing its name to Oodinium poucheti. As a parasitic genus with a compli-
cated life cycle it does not belong with Gymnodiniwm as that genus is at present
constituted, and we therefore reject it, placing it with the Blastodiniidae. With
it and for the same reason we reject G. parasiticum, parasitic on copepods, and
G. affinis from Gymnodinium.

Protozoologists following Stein placed in this genus forms representing
Gymnodinium, Gyrodinium, Cochlodinium, and Pouchetia as here constituted.
Bergh (1881b) added to the genus G. gracile and also G. spirale, later changed
by Schutt (1896) to Spirodinium spirale and by us to Gyrodinium spirale. The
same year Penard (1881) described G. helveticum, G. mirabile, G. mirabile var.
rufescens, changed by Lemmermann (1900) to G. rufescens and G. viride
(=G. uberrinum Allman). Saville-Kent (1880-82) added G. marinum and
Danysz (1886), G. musei. Pouchet described the following species, to which
we add our present allocation of them:

Gymnodinium archimedes, (1883) = Cochlodinium archimedes Lemmermann (1899).

G. sptrale var. striatum, (1883) = Gyrodinium fissum Kofoid and Swezy.

G. spirale var. cornutum, (1885a) = Spirodinium cornutum (Pouchet) Lemmermann
(1899) = Cochlodinium cornutum (Pouchet) Kofoid and Swezy.

G. teredo (1885a) = Torodinium teredo (Kofoid and Swezy).

G. crassum, (1885b) = Spirodinium crassum (Pouchet) Lemmermann (1899) = Gyro-
dinium crassum, Kofoid and Swezy.

Z. polyphemus, (1885b) = Pouchetia polyphemus (Pouchet) Kofoid and Swezy.

G. helix (1887) = Cochlodinium helix (Pouchet) Lemmermann (1899).

G. polyphemus var. nigrum, (1887) = Pouchetia nigra (Pouchet) Lemmermann; (1899)
= Protopsis nigra (Pouchet) Kofoid and Swezy.

G. pulvisculus = G. poucheti, Lemmermann (1899) = Oodinium poucheti (emmermann)
Chatton (1912).

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 171

G. polyphemus var. roseum, (1887) = Pouchetia rosea (Pouchet) emend. Kofoid and
Swezy.

G. gracile var. exiguum, (1883) = incertae sedis, not G. gracile.

G. punctatum var. grammaticum (1887) = G. grammaticum (Pouchet) Kofoid and Swezy.

G. pseudonoctiluca (1885a).

G. punctatum, (1887).

G. wilezeki, (1894).

Biitschli (1885) added no new species to the genus, but includes in it
Pouchet’s G. archimedes and Bergh’s G. spirale. Schilling (1891a) added to
the fresh-water species the following: G. carinatum; G. hyalinum = Spiro-
dinium hyalinum (Schilling) Lemmermann (1900) = Gyrodinium hyalinwm
(Schilling) Kofoid and Swezy; G. paradoxum, and G. pusillum = Gyrodinium
pusillum (Pouchet) Kofoid and Swezy.

Levander (1894) added G. fisswm, which was changed by Lemmermann
(1900) to Spirodinium fissum and by us to Gyrodinium fissum. Schutt in
his first treatment of the subject (1895) included the species Spirodinium
(= Gyrodinium) and Cochlodinium in Gymnodinium, but the following year
(1896) he established these two genera, making Gymnodinium spirale Bergh
the type for Spirodinium and Gymnodinium strangulatum (Schutt) the type
for Cochlodinium by monospecific citation. He failed, however, to sort out the
representatives of these two new genera from the remaining twenty-two new
species which he had earlier described as Gymnodinium. These are given in
the following list with their present allocation, if changed:

Gymnodinium spirale var. acuta—= Spirodinium spirale var. acutum (Sehutt) Lemmer-
mann (1899) = Gyrodinium acutum (Sehiitt) Kofoid and Swezy.

G. constrictum = Cochlodinium constrictum (Schitt) Lemmermann (1899).

G. contortum = Gyrodinium contortum (Schiitt) Kofoid and Swezy.

G. cornutum = Spirodinium schuettw Lemmermann (1899) = Gyrodinium cornutum
(Schiitt) Kofoid and Swezy.

G. cucumis.

G. diploconus.

G. fusus.

G. geminatum = Cochlodinium geminatum (Schiitt) Lemmermann (1899).

G. gleba.

G. lunula.

G

. spirale var. mitra = Spirodinium spirale var. milra (Schutt) Lemmermann (1899) ==
Gyrodinium mitra (Schiitt) Kofoid and Swezy.

G. spirale var. obtusa = Spirodinium spirale var. obtusum (Schiitt) Lemmermann (1899)
= Gyrodinium obtusum (Schiitt) Kofoid and Swezy.

G. opimum = Gyrodinium contortum Kofoid and Swezy.

G. ovum = Gyrodinium ovum (Schiitt) Kofoid and Swezy.

G. parvulum = Gyrodinium parvulum (Schiitt) Kofoid and Swezy.

rt. spirale var. pepo—NSpirodinium spirale var. pepo (Schiitt) Lemmermann (1899) =
Gyrodinium pepo (Sehiitt) Kofoid and Swezy.

G. spirale var. pinguis = Spirodinium spirale var. pinque (Schutt) Lemmermann (1899)

= Gyrodinium pinque (Schiitt) Kofoid and Swezy.

172 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

G. pirum = Cochlodinium pirum (Sehiitt) Lemmermann (1899).
7. rete = incertae sedis, probably near Hemidiniwm.

t. rhomboides.

G. vestifici.

G. viride = Gyrodinium foliaceum Kofoid and Swezy.

Maskell (1887) deseribed G. varians, Lauterborn (1894) followed with G.
tenuissimum, and Lemmermann (1900) added G. zachariasi (Zachariasi). In
1902 Calkins added the species G. gracile var. sphaerica, changed by us to G.
sphaericum. Dogiel (1906) described G. coeruleum, G. affine, G. parasiticum,
G. roseum (= Chytriodinium roseum, Chatton, 1912), and G. spirale var. obtu-
sum, changed by us to G. heterostriatum, Kiister (1908) added G. fucorum, an
imperfectly characterized Gyrodinium. Obno added G. biciliatum in 1911. In
1912 Klebs described G. bogoriense, G. minimum, which we consider identical
with G@. varians Maskell, and G. rotundatuwm. In the same year Jorgensen
added to the list G. pyrocystis. Lebour (1917b) was the last investigator to
add to this list with the following:

G. achromaticum, G. filum, G. minor, G. pseudonoctiluca Pouchet = G. fulgens Kofoid and
Swezy.

G. viridis = G. conicum Kofoid and Swezy.

G. triangularis, a doubtful species.

The genus Protodinium (Lohmann, 1908) presents the characteristics of
the genus Gymnodinium without distinct generic features of its own, hence we
place it with Gymnodinium, and the single species Protodinium simplex Loh-
mann as Gymnodinium simplex.

The following is a summary of the species which we consider valid in the
foregoing list, giving (1) the fresh-water species and (2) the marine forms:

(1) Gymnodinium aeruginosum Stein, G. biciliatum Ohno, G. bogoriense
Klebs, G. carinatum Schilling, G. fuscum (Ehrenberg) Stein, G. helveticum
Penard, G. mirabile Penard, G. musei Danysz, G. palustre Schilling, G. para-
doxum Schilling, G. rotundatum WKelbs, G. roseolum (Schmarda) Stein, G.
tenuissimum Lauterborn, G. uberrimum (Allman) Kofoid and Swezy, G. varians
Maskell, G. viride Penard, G. vorticella Stein, G. zachariast Lemmermann.

(2) Gymnodinium achromaticum Lebour, G. coeruleuwm Dogiel, G. cucumis
Schutt, G@. diploconus Schitt, G. filum Lebour, G. fusus Schiitt, G. gleba, G.
gracile Bergh, G. grammaticum (Pouchet), G. lunula Sehiitt, G. marinum
Saville-Kent, G. minor Lebour, G. pseudonoctiluca Pouchet, G. punctatum
Pouchet, G. pyrocystis Jorgensen, G. rhomboides Schiitt, G. simplex (Loh-
mann), G. sphaericum Calkins, G. vestifict Schiitt, G. wilezeki Pouchet.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 173

In addition to these forty-one valid species above enumerated we consider
that the following must be placed in the list of incertae sedis for lack of sufficient

data:

RR

RRRRARQ RQ RR RAR

The

. affine Dogiel (1906).
. corpusculum (Perty) Saville-Kent (1880-82) (= Peridinium corpusculum Perty and

Proaulax corpusculum (Perty) Diesing.

. gracile var. exiguum Pouchet (1883).
. glaciale Danysz (1886).
. nerme (Perty) Saville-Kent (1880-82) (— Peridinium inerme Schmarda 1854 and

Heteraulax inermis (Schmarda) Diesing (1866) as a synonym of G. monadicum).

. lachmanni, Saville-Kent (1880-82) (= Peridinium sp. Claparéde and Lachmann).
. lohmanni Paulsen (1908) (—G. rosewm, Lohmann, 1908), pl. 17, fig. 25. His figures

26-28 of the same plate are evidently Gyrodiniwm.

. monadicum (Perty) Saville-Kent (1880-82) (= Peridinium monadicum Perty, 1852).
. monas (Ehrenberg) Saville-Kent (1880-82), cited by Kent as possibly the same as G.

marinum. Indeterminable.

. paradoxum var. major (Lemm.) West and West (1906). May be G. paradoxum.
. rete Schiitt (1895). May be Hemidinium.

. simplex (Lohmann) 1908 (= Protodinium simplex).

. tintinnicola Lohmann (1908).

. triangularis Lebour (19176).

following are placed in the list of nomina nuda:

. asymmetricum Massart (1901).

. cruciatum Massart (1901).

. polyphemus var. magna Dogiel (1906).
. minutissimum Massart (1901).

. vorax Massart (1901).

following species, included at some time heretofore in Gymnodinium,

have been transferred by others or are by us here transferred to other genera:

G.

RAARR A®

RR RW’ RA’ RQWR

spirale var. acuta Schiitt (1895) to Gyrodinium nom. gen. nov. by us in this paper as
G. acutum.

. archimedes Pouchet (1883) to Cochlodinium by Lemmermann (1899).
. bicaudatum Pavillard (1905) to Heterodinium bicaudatum (Pavillard) by us in this

paper.

. constrictum Schiitt (1895) to Cochlodinium by Lemmermann (1899).
. contortum Sehiitt (1895) to Gyrodintum nom. gen. noy. by us in this paper.
. cornutum Sechiitt (1895) to Gyrodinium nom. gen. nov. by us in this paper.

spirale var. cornutum Pouchet (1885a) to Gyrodiniwm nom. gen. noy. by us as G. cor-
nutwm in this paper.

. crassum Pouchet (18854) to Gyrodinium nom. gen. noy. by us in this paper.

. fissum Levander (1894) to Gyrodinium nom. gen. nov. by us in this paper.

. fucorum Kiister (1908) to Gyrodinium nom. gen. nov. by us in this paper.

. geminatum Sechiitt (1895) to Cochlodinium by Lemmermann (1899).

. helix Pouchet (1887) to Cochlodinium by Lemmermann (1899).

. hyalinum Schilling (1891a@) to Gyrodinium nom. gen. noy. by us in this paper.

. spirale var. mitra Schiitt (1895) to Gyrodiniwm nom. gen. nov. by us in this paper as

G. mitra.

G.
G.
G.

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

nasutum (Stein) Levander (1900) to Hemidinium by us in this paper.

noctiluca Pouchet (1885a) to Noctiluca miliaris by us in this paper.

polyphemus var. nigrum Pouchet (1887) to Protopsis nom. gen. nov. by us in this paper
as Protopsis nigrum.

. spirale var. obtusa Schiitt (1895) to Gyrodinium nom. gen. noy. by us in this paper as

G. obtusum.

-opimum Sehiitt (1895) to Gyrodinium nom. gen. noy. by us in this paper.

. ovatum Gourret (1883) to Gyrodinium nom. gen. noy. by us in this paper.

. ovum Sehiitt (1895) to Gyrodinium nom. gen. nov. by us in this paper.

. parasiticum Dogiel (1906) to Oodinium parasiticum (Dogiel) Kofoid and Swezy.

_ parvulum Schiitt (1895) to Gyrodinium nom. gen. nov. by us in this paper.

7, spirale var. pepo Schiitt (1895) to Gyrodinium nom. gen. nov. as G. pepo by us in this

paper.

. spirale var. pinguis Sehiitt (1895) to Gyrodinium nom. gen. nov. as G. pinguis by us

in this paper.

. pirum Sehiitt (1895) to Cochlodinium by Lemmermann (1899).
. polyphemus Pouchet (1887) to Pouchetia polyphemus (Pouchet) emend. Kofoid and

Swezy.

. poucheti Lemmermann (1899) (== Gymnodinium pulvisculus Pouchet, 1885a) to Oodi-

nium poucheti (Lemmermann) by Chatton (1912).

. pulvisculus Pouchet (1885a) to Oodiniwm poucheti (Lemm.) by Chatton (1912).
. pulvisculus (Ehrenberg, 1830) Stein (1878) to Glenodinium pulvisculus (Khrbg.) by

Stein (1883).

. pusillum Sehilling (1891a) to Gyrodinium nom. gen. nov. by us in this paper.
7. roseum Dogiel (1906) to Chytriodinium roseum (Dogiel) by Chatton (1912).
. polyphemus var. roscum Pouchet to Pouchetia rosea (Pouchet) Kofoid and Swezy

emend.

. spirale Bergh (18816) to Gyrodinium nom. gen. nov. by us in this paper.
. spirale vars. C, D, Pouchet (1883) to Gyrodinium nom. gen. nov. by us in this paper

as G.

. strangulatum Sehiitt (1895) to Cochlodiniwm by Lemmermann (1899).
. spirale var. striatum Pouchet (1883) to Gyrodinium nom. gen. nov. by us in this paper

as G. striatum.

. teredo Pouchet (1885a) to Torodinium gen. nov. by us in this paper.
. viride Schiitt (1895) to Gyrodiniwm nom. gen. noy. by us in this paper.

Subgenera of Gymnodinium

SuBGENus 1. Gymnodinium subgen. noy.

Medium to small sized species, with or without chromatophores, surface free
from markings or if present few and scattered. The type species is G. fuscum
(Ehrenberg). This subgenus includes besides the type: G. aeruginosum Stein,
G. agile sp. nov., G. auratum sp. nov., G. biciliatum Ohno, G. bicorne sp. nov.,
G. bogoriense Wlebs, G. carinatum Schilling, G. cinctum sp. nov., G. conicum
nom. sp. nov., G. contractum sp. noy., G. dissimile sp. nov., G. doma sp. nov.,
G. filum Lebour, G. flavum sp. nov., G. fulgens nom. sp. nov., G. fusus Schiitt,
G. grammaticum (Pouchet), G. herbaceum WKofoid, G. tmeisum sp. nov., G.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 175

lineopunicum sp. noy., G. lunula Schutt, G. marinum Saville-Kent, G. minor
Lebour, G. mirable Penard, G. musei Danysz, G. ovuluwm sp. nov., G. palustre
Schilling, G. paradorum Schilling, G. pseudonocticula Pouchet, G. punctatum
Pouchet, G. pyrocystis Jorgensen, G. ravenescens sp. nov., G. roseolum
(Schmarda), G. rotundatum Wlebs, G. rubricauda sp. nov., G. scopulosum sp.
noy., G. simplex (Lohmann), G. sulcatum sp. nov., G. tintinnicola Lohmann,
G. uberrimum (Allman), G. varians Maskell, G. viride Penard, G. violescens
sp. nov., G. vorticella Stein, and G. zachariasi (Zacharias).

Supcenvs 2. Lineadinium subgen. nov.

Periplast thin, ‘surface striate with parallel linear striae on epicone and
hypocone. Generally of large size.

Type species is G. heterostriatum nom. sp. nov. It includes also the fol-
lowing species: G. achromaticum Lebour, G. attenuatum sp. nov., G. aureum
sp. nov., G. cucumis Schiitt, G. diploconus Schiitt, G. hamulus sp. nov., G. hel-
veticum Penard, G. lineatum sp. nov., G. multilineatum sp. nov., G. multistri-
atum sp. nov., G. rhomboides Schutt, G. rubrum sp. nov., G. translucens sp. noy.,
G. vestifict Schiitt.

SUBGENUS 3. Pachydinium subgen. noy.

Pellicle distinctly thickened, usually conspicuous as a wide zone around the
body, with the outer alveolar layer making the surface bossed or mammilate.
Surface marked by striae or ridges, or smooth. The type species is G. pachy-
dermatum sp. nov. It includes besides the type: G. abbreviatum sp. nov., G.
amphora sp. nov., G. bifurcatum sp. nov., G. canus sp. nov., G. coeruleum Dogiel,
G. costatum sp. nov., G. dogieli sp. nov., G. gleba Schiitt, G. gracile Bergh, G. lira
sp. nov., G. puniceum sp. noy., G. radiatum sp. nov., G. sphaericum Calkins, G.
situla sp. nov., G. tenuissimum Lauterborn, and G. wilczeki Pouchet.

SPECIES OF UNCERTAIN Status IN Gymnodinium

Owing to the fact that a free, non-thecate phase of brief duration may occur
in the life history of the Peridinioidae, it is possible to mistake them for the
true Gymnodinioidea. The characteristics which distinguish such phases are
little known. These phases are wont to be more active than the thecate phase
of the species and to be less frequently observed and less completely described.
The activity of the unarmored forms in general tends to introduce into liter-
ature records of species based on partial observations which do not reveal the
relationships or establish the status of the form described.

The following species described in the genus Gymnodinium are in our
opinion so imperfectly characterized as to render their allocation tentative and
to require fuller description before their status therein and their relationships

176 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

can be determined: Gymnodinium bicaudatum Pavillard (1905), G. corpus-
culum (Perty, 1852) Saville-Kent (1880-82), G. gracile var. exiguum Pouchet
(1883), G. inerme (Schmarda) Sayille-Kent, G. lachmanni Saville-Kent (1880-
82), G. lohmanni (Lohmann, 1908), G. monadicum (Perty, 1852) Saville-Kent
(1880-82), G. punctatum Pouchet (1887), G. rete Schiitt (1895), G. simplex
Lohmann (1908), G. tintinnicola Lohmann (1908), G. triangularis Lebour
(1917b), G. monas (Ehrenberg, 1840), Saville-Kent (1880-82).

In the following discussion of the species of the genus Gymnodinium an
alphabetical arrangement of both the valid and doubtful species has been
preserved solely as a matter of convenience:

Key To THE Spectres oF Gymnodinium

1. Periplast thin, without striae, or if present limited and few ....(subgenus Gymnodinium) 2
1, Periplast tli; swath striae) sees ar eee eee (subgenus Lineadinium) 58
1. Periplast thickened, surface striate or smooth 22... (subgenus Pachydinium) 42
2. Striae or furrows on epicone or hypocone, not on both —-.-----<.-------ccececccccecceceeceece cee cecseeeeeees 3
PMS) 2 2, - e ee eee 5
3. Surface with furrows onepicone: omliys sees ee eee contractum sp. noy.

3) Surface markanes im! hypocone™ onl iyg sarees ae 4
AL VAlb outa Oo EUrr OWS) OL Ly; OC OM essere eee eae ee ee sulcatum sp. nov.

As Elypocone wath S=2.0)is trea essences eee renee ence ee herbaceum Kofoid MSS.

5. (Chromatophores Present 22-2 secs ose se cee cece ace eee eee 6
5 No: chromatophores: 224 2.2 nee ae eee 22
6: Im fresh!-waters (chrom abopnOves: 9 2e eres eeee seer meee eee ee ee TU
6) Chromatophores: yellow, cor smeeirl sys SO eee ene rane 9
7. Girdle postmedian, chromatophores’ scattered 2x o-oo. seeee eee musei Danysz

7. Girdle submedian, disklike chromatophores crowding the periphery....zeruginosum Stein

7. Girdle median, rod-shaped chromatophores radially arranged ~_....-....---22--22----------------2------ 8
8: ueneth, 30 a2...343 se ee viride Penard

Be gern tay, UG pe, cece a se sec ce wa ee varians Maskell

9: Pseudopodia extended! tromysul cus: te eee ee es zachariasi Lemm.

9. Pseudopodiam ot skin owl [tO 1Oc cur <2 ee eee eee 10
LO: Miarine) Speers ieee seb ck ok esc a see en ee 11

10. Fresh-water ispecies: <-v-s=:. Ses 22) ee ee ee eee a

11. Large species, length over 100p
11. Length less than 100,

12. Body biconical, girdle medium length, 122, 2.1 transdiameters — fusus Schiitt

12. Body with conical epicone, girdle premedian, length 100, 2.3 transdiameters —................
wera GOT tweet Se ON) SS re ea fulgens nom. sp. nov.

13%: (Girdle not: displaced 2..1:. 4 2250 2 Se ee ae eee 14

13. Girdle displaced at least its own width

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 177

14. With apical point deflected to the left, body spheroidal 0.0. agile sp. nov.
ab, spore yoxayirays, The Tones SCevaTl, TON AYEy KEN AUX Oe e e P 15
15. Length 1.5 transdiameters, girdle feebly marked ._...................---. simplex (Lohmann)
15. Length 1.2 transdiameters, girdle evident —.................------------- grammaticum (Pouchet)
16. Sulcus not extended far on epicone, length less than 40 222222 17
16. Suleus extending ravecnelyys quay Ay oXeocs VeraV eA ONCE BLOT coe cence e re eee ee 18
17. Epicone and hypocone subequal, girdle not constricting flavum sp. nov.
17. Epicone much smaller than hypocone, girdle deeply constricting cinctum sp. nov.
18. Epicone hemispherical, dark ochraceous ................-.2-----2--2--20e---20e----- conicum nom. sp. nov.
Seekiprconerconicalwereenish\ yellow, ee ee ravenescens sp. nov.
VG) REPL GH ah: CORRES YT a rae ae ee eee eee neo eR 20
TU), I cevaneesgel ah TCSRSISY 8 Na SO ee ee ee EE POP el Pee EPA 21
20. Suleus extending short distance on epicone, girdle slightly displaced
20. Suleus confined to hypocone, girdle not displaced — fuscum (Ehrenberg)
lea eva cot hil OU ge boy el etree SCHL ATT eG TS ieee cee eee nn nC PE 22
ieeWvenotheapoutmle savor eomunansdi ane ters ess eee ee oe mee Seen se ene eee 24
22. Girdle slightly displaced, length 45, yellowish brown — uberrimum (Allman)
BP. (Give alley saKay > @UtSy oy EV Ce, ea ence pee er ee pe ea ee ee ee ee 23
23. Length 444, over 1.5 transdiameters, yellowish brown .|...............0..--..-- palustre Schilling
23. Length 40y, 1.3 transdiameters, dark brown ..............2...22022-200ece0---- paradoxum Schilling
Paswenrthi stu. leoytransdiametens., yell owishie 5s rotundatum Klebs
em erotically bE an SCM Ge TS geese eee eee eee en carinatum Schilling
ES EN OY AS AP Ye ea PREP Pe ee oe Ee eee 25
Zoe Sul cUssextends shorbidistancevonpeplcOMe see en biciliatum Ohno
ZO NOUS CUS BODKC DIC OG «2-2 onic ewe oe a ae eee Me ee ie ee bogoriense Klebs
2 Oem OV COD ASTM COL ONG Cigeese cs eerete sets ant cesar ee et Ee eer Sen eas eee EO ae Sn 2 tena eens 27
A Gim OVC OP ASI COLOTLESS pee fo ete ees cece ceca rane ee ee ra ee, NL I CT Sey ee 37
27. Fresh-water, cytoplasm pink, girdle premedian — roseolum (Schmarda)
PACs IEEE TE ORIEN Bt ee aoe eee | 28
2 Semin OM enibeIM ASSES RESCIUGe. ere tee ee eee ee es, Se ee ogee AS ee ce. 29
See NOMPISIT CHURN ASSES a LESCMIi pares eee eee ee cue cae ee Ade eer a ee ee 30
29. Pigment pomegranate purple, peripheral -..............-......2-------eeeeeeenee- lineopunicum sp. noy.
29. Pigment pansy violet, in disks or scattered ..................-..-.--0e-ceeeeeeseeneee-es violescens sp. noy.
29. Pigment rose red, diffused, and im. spherules .............-..-----------s-eeeee-eoee rubricauda sp. nov.
30. Length over 100y, girdle premedian, LeEmMpPOrarys LEM LACE MPLES CIM pee seen sre serene sere eee
a ear ee Pm ese oot Be brace concn boosts! pseudonoctiluca Pouchet
Mae yer OL eSrmt Lear )) pene sc ccs eect eee sce wet eee ce eee eae be Sau ebce cara Wore See Oe gee 31
31. Girdle premedian, epicone low hemispherical, suleus short —..........---.-.-.-.... doma sp. noy.
31. Girdle not premedian, sulcus extends from apex to antapeX ........-....-.-..--c-:cecceceeceececeeeeeneeeeess 32

178 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

32. Girdle} postmedian; preyasheoreen 14 Sic) ese eee ee dissimile sp. nov.
325 Girdle smediam-(or sib rie cern eae co ee aa ee eo 33
33. Length equaling transdiameter, suleal notch present —....-....----.----------------- incisum sp. nov.
332 Wengthemorethanwle2 transi am et ers gases eee 34
34. Length over 2.5 transdiameters, cyst arcuate —............-..-.-----c-ee-eeeeceeeeeeeeee bicorne sp. noy.
34 Menethslessthan two transdiameters) = ee 35
35. Length 1.8 transdiameters, 47, girdle displaced 0.3 transdiameter...scopulosum sp. nov.
35. Length less than 1.5 transdiameter, girdle slightly displaced _........-.--.----.2..2--2.-2----------------- 36
36. Spherical and lunate cysts common, free form 22u, 1.22 transdiameters.....lunula Schiitt
36. Cysts unknown, length 62, 1.4 tramsdiameters —...........------.-------------------- auratum sp. nov.

7. Fresh-water species, girdle postmedian, length less than 30p -..................... vorticella Stein
SITE (Miarime: Sp Ci OS axe S owe ces as cea a a a 38
385 duarge ispeciesssleng ths 20 0 pares sess nearer eee pyrocystis Jorgensen
38: Wess*than l00,-m length: - 2... 222s ee ee 39
39. Girdle postmedian, body broadly ellipsoidal -...............2.-...2.--..-ee-eeeeeee eee eee minor Lebour
39 Girdlepremedianx orm early:«SOsce ee ee 40
40» Body. slendersbiconical--...3..2 2. - oe eee filum Lebour
AO! sBodysspleroid alles. 2c oo ea ee ovulum sp. noy.
40. Body ovoidal, dorsoventrally compressed ..............-..-.2-----0-------00-00--- marinum Saville-Kent
41. Body with thickened periplast, striate or non-striate, Pachydinium subgen. nov. -............ 42
417 ‘Periplast: thin, striate; Lineadinium) subgens 10 va eee 58
42), Tiarge species over LOO psn] enn this 2see ere ee ee 43
QD" Wess thar Oj. rar al er ort ae asa es eee ee ee ee ee 54
43:>-Surfacerstriatexor srr 0 wed) occ eee ee ee eee 44
£3 SuLlace mot marked swat ke Seba CM OTN CET O WS pee eae 50
44~ Striae-snbequall onvepiconevand shypocore sess eee eee eee 45
AAS Stas OLE HELIN CLOUS 7 OF Yip) OG OTIC ese see 47
45. Girdle premedian, striae broken, surface rough, color pink ............ abbreviatum sp. nov.
455 (Gardke ss ua bree eee e eS E e a e a OE 46
46. Epicone contracted obliquely on dorsal surface, greenish — 0. canus sp. noy.
AIG HB PICONEy S yar bre] Call gp geese costatum sp. noy.
47. Colorabliaesy eirale rn e ohare ences e ace e eae c eee e coeruleum Dogiel
Ai Color mot markedlyablues urd ley prem e chien yee eee 48
48. Length over 2 transdiameters at girdle, epicone conical -..........-.......------------ gracile Bergh
48" ength mot over ?2 trams aries ers esse serene eee 49
49. Epicone 0.35 total length, color onion-skin pink .......-......-2.-------------------- puniceum sp. noy.
49. Hpicone 0:40 total length, color greyish green <_--<-222--occeccc cece ccececeeeeeeceeeee eee lira sp. noy.
50. Surface roughened by alveolar layer, ectoplasm distinet —.....-2----2e eee 51
50) Surface smooth, ‘ectoplasm er oti cist Cty eee 53

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 179

51. Epicone coneave conical, girdle submedian, scarcely displaced dogieli sp. nov.
51. Epicone convex, subhemispherieal, girdle slightly displaced 52
DE DICONE ra OU OFS Ow LO bel lad CYNE a eee seem eae enc ee een ant ee ey amphora sp. nov.
HOME piconemn earlva Os cOuale lem Ct) eesss meee ee ere, Bente pachydermatum sp. noy.
53. Hypocone bifureated about 0.8 its length, color pink 2. bifurcatum sp. nov.
53. Hiypocone not bifureated, color greenish grey —.-........-.2-.-.---cccccecececeeececeeeeeeoeeeees gleba Schiitt
AMES UIELA CORSET ALE HO lem ULE TO WiC Cl rere cassettes cece eae Oe Re Se ere Re SO cece cee rate eee eee 55
Eh, SHUUETENES, TONE RUTTER TRNTEO ECL ace ceetiec sete ses ate eco ae es eee eee eo eee ee ec coo 57
55. Coarsely striate, girdle scarcely displaced, submedian .~........-.-.................- wilczeki Pouchet
Howinelyastriate seirdlerpreme diam at wleas trjorso xr alllliys: sete e a senses core even ee eeaee ese eee 56
56. Girdle distinetly premedian, scarcely displaced, epicone low conical .......... situla sp. nov.
56. Girdle premedian proximally, displaced 2 furrow widths, epicone hemispherical -.............

eae mame eae UN ir Seaver ee ok at ks 2 pe Me oe Ee radiatum sp. nov.
57. Body dorsoventrally compressed, fresh-water -.................------------- tenuissimum Lauterborn
elo LEX by? TaNoye, LoKoyaaly ORE TS(EKOL, ane WES AVE)! cso ere ee sphaericum Calkins
S GMMeT Use OF OLE META SCAN CLC Ts eee re err te ene oe ere Sacer e ees Seee 59
Iso}, Ieuan ilay Wess) oem, 3, (eek ECS eS eee ee ee pe A Oe SEE 60
HOmene teal pas orinclll ers wally re Chi earn pees eee ee cucumis Schiitt
YB) Wbeewaveailen 457m, featetallbey Sikes MANN CN ON eee ee a eee eee eee se ee vestifici Schiitt
(XD), od RAVE goa ET AMES ONESTAT Eh ce cc see pe a a aS ae ee a et ier eee eee 61
GORI omrent en oben es er tess ee nee ee om ee Re ee eo eee 62
61. Girdle premedian, striae on hypocone more numerous than on epiecone, rose red —

Pe a ened ee en ee a ae A oh 2 ee ee Tee a ee rubrum sp. nov.
61. Girdle submedian, striae equal in number on epicone and hypocone, rose red —_..-

a eT ee CN ce tan te ese ese es lineatum sp. nov.
62. Length less than 20, apical point deflected to left -.......2222222---eeeeee hamulus sp. nov.
62. Length over 20n, apical point, if present, not strongly deflected — eee 63
GS emR ECC CO Topto Tin mene cer Re seh ea A Nee rere CEN ne cate, | Bote de he ea me ah resale Res ere 64
G3 eNO tier GeO lamp Lin kigpee eieee eer ne Ro, AE Pas dee 2 oan eee eee ee ee ee eee 65
64. Fresh-water habitat, striae equal on epicone and hypocone —...... helveticum Penard
64. Marine habitat, striae more numerous on hypocone ............... heterostriatum nom. sp. noy.
65. Girdle not displaced, body biconical, yellow. .........-.-..-.---:c-c--c--c-cseeeceeenees diploconus Schiitt
(Fay MG tiga Key, COLTSY YANCY «Ye eee ee ee Pe ae
66eslhenotheomnore) ub ama Deir ani Sct AMC LCT ase see eee cases tae sere eee ec eeeeeee
66. Length less than 2 transdiameters
67. Body biconical, apices tapering, length 65yp ................22-.---.--eseeeeeeeeeee attenuatum sp. noy.
GieeBodyeeloneaterellapsordalls Vero th sllO0 pitcccccrcsssescesse-eseeceeseescesrere-eeceeeeee multilineatum sp. nov.
GOMCOlorlessairanSlUCentmOr nD LUIS lal eecset tree eats. Rr ee cae se ene nae a eee gereatunceeee ee 69
Gian © OL Ormey Cll O yim setae ten oe easter Seer o ne nA Niae, eee ba sete NG Cook Soles evcnenewegtacees 71

180 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

69. Body symmetrically biconical, length 46p ~.__........2--.------.------s-eeeeeeeeeeee rhomboides Schiitt
69° Body: ellipsoidal leneth oven: (0 yess ee 70
70. Girdle median, minute apical point present -..........-..---------.------0----3------ translucens sp. nov.
10}, (Girdleypremedian..apex broadly, rounded ee ee achromaticum Lebour

71. Hypocone rotund below girdle, color ochraceous yellow, striae more numerous on hypocone
se AEA BS oh eee AAA e ak ct wc ee multistratum sp. nov.

71. Hypocone contracted below girdle, color, strontium yellow, striae equal on epicone and
119 01001090: ere Pee aureum sp. nov.

Gymnodinium abbreviatum sp. noy.
Plate 6, figure 63; text figure Z, 7

Dracnosis.—A medium sized species with elongate ovoidal body, its length
1.94 transdiameters; hypocone elongated; girdle premedian with displacement
of 0.26 transdiameter; sulcus extending from apex to antapex; differentiated
ectoplasm; surface striate and mammillated; color, hydrangea pink. Length,
97". Pacific off La Jolla, California, July, August.

DescripTion.—The body is long, elongate, asymmetrically ovoidal, widest anteriorly at the
girdle, rounded at the apices and cireular in cross-section, its length 1.94 transdiameters at the
widest part. The hypocone greatly exceeds the epicone in size, its length being greater than the
extreme length of the latter by 0.27 of itself. The epicone is subconical (80°) in shape, flaring
widely towards the girdle, with a blunt, rounded, somewhat eccentrically placed apex inclined
dextrally. It has a length on the left and right sides of 0.3 and 0.47 respectively of the total
length of the body. The hypocone is long, flaring slightly anteriorly, tapering posteriorly, with
asymmetrically rounded antapex slightly notched by the suleus, the left side being somewhat
longer than the right.

The girdle is premedian in position, its proximal and distal ends joining the suleus at distances
from the apex of about 0.3 and 0.47 respectively of the total length of the body. About 0.75 of
its course around the body is in a transverse direction and the remainder is deflected posteriorly,
its distal end meeting the girdle at an angle of about 45° with the main axis of the body, with a
displacement of 0.26 transdiameter. The furrow has a width of 0.06 transdiameter, and is rather
shallow with overhanging borders, the lips of which present a crinkled outline caused by the
unevenness in the surface of the body. The suleus extends from the apex to the antapex, begin-
ning at the left of the apex and terminating at the right of the antapex. It forms a deep trough,
narrowed above and below its junctions with the girdle and enlarging considerably between
them. Its borders are smooth throughout. The anterior flagellar pore opens at the anterior
junction and the posterior pore at the posterior junction of the girdle and suleus.

The nucleus is a large, ellipsoidal body located in the posterior half of the hypocone. Its
chromatin contents are arranged in fine moniliform strands. Its major and minor axes are about
0.48 and 0.44 transdiameters in length respectively.

Club-shaped pusules may be present at either or both pores. The cytoplasm is finely granular
and is frequently filled with large salmon pink vacuoles. Besides these, oil globules of varying
sizes and minute refractive granules are generally abundant. Near the anterior flagellar pore
a large olive green food mass was present in the individual figured. The general color of the
organism is hydrangea pink diffused throughout the cytoplasm. The ectoplasm forms a thick,
distinet layer and is composed of large bosses with the outer surface rounded, giving the outline

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 18]

of the body a distinetly wavy appearance (fig. Z, 7). This layer is about 1p in thickness. On
the surface of the body are striae of broken lines, linearly arranged and spaced at about 3y
near the girdle, twenty-three across the ventral face.

Dimensions.—Length, 97-1154; transdiameter, 50-75; axes of nucleus,
25-364 and 22-28.

OccuRRENCE.—The individual figured was taken July 9, 1917, 4 miles off
La Jolla, California, with a No. 25 silk net in a haul from 80 meters to the
surface and in a surface temperature of 19°2 C. On July 11 another individual
was observed in a surface haul made at the same place, with the same apparatus.
It was seen again on August 13, 0.75 mile off La Jolla in a haul from 83 meters
to the surface.

Comparisons.—Lebour (1917b) describes a form to which she gives the
name G. achromaticum, which is somewhat similar to our species, and yet
presents striking differences. The general shape and proportions differ only
in a slight degree (fig. Y, 8). The most striking difference is in the lack of a
differentiated ectoplasm in G. achromaticum, which in G. abbreviatum gives
the characteristic appearance to the surface. This species shows the same
differentiated ectoplasm found in G. dogieli sp. nov., G. pachydermatum sp. nov.,
and G. amphora sp. nov. (figs. AA, 1, 5, 6), and, like them, it belongs to the
subgenus Pachydinium. In its color it stands alone in Gymnodinium, and in
displacement of girdle exceeds that in the species above named.

Gymnodinium achromaticum Lebour
Text figure Y, 8

Gymnodinium achromaticum Lebour (1917b), p. 190, fig. 5.

DraGnosis.—A medium sized species with ellipsoidal body, its length 1.62
transdiameters; girdle premedian, displaced about twice its own width; suleus
extending from girdle to antapex; surface coarsely striate; colorless. Length,
78. Plymouth Sound, England, July.

DescripTION.—The body is asymmetrically and broadly ellipsoidal in ventral view, with
broadly rounded apices, ovoidal in lateral view, narrowing posteriorly, its length 1.62 trans-
diameters at the widest part. The narrowing of the dorsoventral diameter occurs only in the
posterior part of the hypocone. The epicone is much smaller than the hypocone, being exceeded
in length by 0.24 of the length of the hypocone. Its shape is that of a broad, flat cone, about
90° in lateral view, 120° in ventral view, with blunt apex excentrically placed sinistro-ventrad.
It has a length on the left and right sides of about 0.29 and 0.48 respectively of the total length
of the body. The hypocone is long with subparallel sides in ventral view, tapering posteriorly
in lateral view. The antapex is broad and truncate, marked ventrad by the suleal noteh.

The girdle is premedian, joining the proximal end of the suleus at a distance from the apex
of about 0.29 of the total length of the body. It sweeps around the body in a descending left
spiral course, its distal end joining the sulcus 0.48 of the total length of the body from the apex,
and is displaced about twice its own width. The furrow is wide, about 0.08 transdiameter, and
is deeply impressed, with overhanging sides. The suleus apparently extends upon the epicone
for a short distance and posteriorly to the antapex in a slightly sinuous line. The flagella and
pores are not figured by Lebour (1917)).

182 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The nucleus is ellipsoidal and is situated in the posterior part of the body. It is filled with
chromatin strands which traverse its longer axis. Its major and minor axes are about 0.62 and
0.43 transdiameters respectively in length.

The surface is sparsely covered with longitudinal striae, about ten across the ventral face,
apparently equal in number on the epicone and hypocone. The organism is stated by Lebour
(1917b) to be perfectly colorless and transparent.

Diuenstons.—Length, 78; transdiameter, 48“; axes of nucleus, 32 and 21+.

OccuRRENCE.—A single individual was seen by Lebour (1917b) July, 1915,
in a haul made in Plymouth Sound, England.

Comparisons.—It falls within the subgenus Lineadinium by reason of its
thin periplast and striate surface in the group including also G. puniceum
sp. nov. (fig. Z, 5) and G@. wilezeki Pouchet, species with rotund body and sparse
striae. Its girdle displacement separates it from G. puniceum and its small
epicone from G. wilczcki. This form resembles G. abbreviatum somewhat
closely, vet differs from it in its lack of a thick ectoplasm, in its fewer striae,
and in its slightly different proportions.

Gymnodinium adriaticum (Schmarda) Kofoid and Swezy

Peridinium adriaticum Schmarda (1846), pp. 19, 36, 62, pl. 2, figs. 1, 1-5; (1847), p. 12.
Heteraulacus adriaticum, Diesing (1850), p. 100.

Heteroaulax adriatica, Diesing (1866), p. 95.

Peridinium adriaticum, Stein (1878), p. 72.

P. adriaticum, Maggi (1880a), p. 14; (1880b), pp. 314, 326.

P. adriaticum, Imhof (1886), p. 101.

Not Peridiniwm adriaticum Broch (1910), pp. 179, 191-193, fig. 8.

DiaGnosis.—Body stout, ellipsoidal with hemispherical apices, its length 1.5
transdiameters, widest at the girdle; epicone and hypocone subequal; girdle
equatorial without displacement or overlap; sulcus straight, slight suleal notch ;
ochraceous; length, 30-54". Adriatic Sea.

DescripTION.—The body is very symmetrically ellipsoidal, transverse and dorsoventral diam-
eters equal; its length 1.43-1.54 transdiameters, widest at the girdle, which is equatorial in
location. The epicone and hypocone are subequal, each a little more than a hemisphere by
elongation near the girdle, apex rounded, antapex with broad shallow suleal notch. The girdle
is transverse, without deflection or overlap, and the sulcus is confined to the hypocone. The
transverse flagellum encircles the body, while the longitudinal one projects 0.8 of the length of
the body behind the postmargin, but the origin of the flagella is not shown.

The nucleus is subeentral, to the left and posterior to the girdle. It is spheroidal, 0.23 trans-
diameter in diameter. Cytoplasm with numerous small spherules. Color ochraceous.

Dimensions.—Length, 35-54; transdiameter, 30-35, rarely 21—45r.

OccURRENCE.— Deseribed by Schmarda (1846) as very abundant in salt pools
of St. Servola on the northern coast of the Adriatic Sea, and as rare in ponds
filled by sea water from the inner Venetian lagoons, but abundant in a similar
pool at the Forts of the Lido at Venice. It was not found by Imhof (1886),
who examined the plankton in Venetian lagoons, and, though cited in literature,
has not been reported since its discovery by Schmarda.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 183

SynonyMy.—Described by Schmarda (1846) as Peridinium adriaticum and
transferred by Diesing (1850) to his genus Heteraulacus and later (1886) to
Heteroaulax.

In 1910 Broch described from the Adriatic a true thecate Peridinium which
he named adriaticum sp. nov. This name is preoccupied by Schmarda’s (1846)
P.adriaticum. We therefore propose the name Peridinium brochi nom. sp. nov.
for Broch’s species.

CoMPARISONS.—This species is close to G. fuscum (Ehrenberg, 1834), but
differs from it as figured in smaller size, stouter body and rounded antapex, as
well as in being a marine instead of a fresh-water form. It is also rather near
G. marinum Saville-Kent (1880-82), but is less constricted and has a relatively
larger epicone.

Gymnodinium aeruginosum Stein
Text figure X, 25

Gymnodinium aeruginosum Stein (1883), pl. 2, figs. 19-22.

. aeruginosum, Biitschli (1885), p. 986.

. aeruginosum, Levander (1894a), p. 48; (18946), p. 210; (1901), p. 6.

. aeruginosum, Schilling (1891), p. 276, pl. 10, fig. 10; (1913), p. 19, fig. 18.
. aeruginosum, Schiitt (1895), pp. 9, 58.

. aeruginosum, Entz (1896), p. 22; (1902), p. 120; (1910), p. 157.
aeruginosum, Butschinsky (1897), p. 195.

aeruginosum, Mez (1898), p. 216.

aeruginosum, Lemmermann (1899), p. 126; (1900), p. 116; (1901), p. 358; (1902), p.
260; (1905), p. 163; (1906), p. 420; (1910), pp. 613-623, figs. 12-14.

. aeruginosum, Schénichen and Kalberlah (1900), p. 231; (1909), p. 252.

. aeruginosum, Amberg (1900), p. 83.

. aeruginosum, Marsson (1901), p. 103.

. aeruginosum, Ruttner (1906), pp. 9, 16.

. aeruginosum, Paulsen (1908), p. 100, fig. 138.

. aeruginosum, Lauterborn (1910), p. 452.

. aeruginosum, Kolkwitz (1911), pp. 347, 371.

. aeruginosum, Klebs (1912), p. 391.

. aeruginosum, Zenker (1912), p. 27.

. aeruginosum, West (1916), pp. 52, 75.

ARARARAA®

RARRRAARRARANK

Diacnosis.—A minute species with ellipsoidal, dorsoventrally flattened body,
its length 1.57 transdiameters; girdle slightly postmedian, without displace-
ment; sulcus extending from the middle of the epicone to the antapex; color
blue green. Length, 334. Fresh water in Austria, Finland, Russia, Germany,
and Switzerland.

DescripTion.—The body is ellipsoidal, widest near the middle, with broad apices, its length
1.57 transdiameters, its dorsoventral diameter 0.3 of its transdiameter. The epicone is slightly
larger than the hypocone, having a length 0.17 greater. It is broadly dome-shaped in ventral
view with broad apex. Its length is 9.5 of the total length of the body. Its sides are rounded
and the antapex is truncate or excavated by the suleal notch.

184 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The girdle is slightly postmedian, its distance from the apex being 0.5 of the total length of
the body. It forms a complete circle around the body. The furrow is about 0.1 transdiameter
in width and deeply impressed with overhanging borders. The sulcus begins midway between
the girdle and the apex and extends posteriorly in a straight line to or near the antapex. The
transverse and longitudinal flagella both arise near together at the junction of the girdle and
suleus.

The nucleus is a spherical body near the apex. Its diameter is about 0.2 transdiameter of
the body. Numerous blue green chromatophores fill the peripheral zone of the cytoplasm and
give their color to the organism.

DiMenstons.—Length, 33-34; transdiameter, 21-22; diameter of sulcus, 5.

OccUuRRENCE.—Figured by Stein (1883) from fresh-water ponds near
Chodau. Austria. Other occurrences reported are as follows: Levander
(18940) from several lakes in Finland and (1894b) near Helsingfors, Finland;
Butschinsky (1897) at Odessa, Russia; Amberg (1900) at Zurich, Switzerland ;
Marsson (1901) near Berlin, Germany; Ruttner (1906) near Prag, Austria;
Kolkwitz (1911) eastern Russia and western Germany; Entz (1896) in Hun-
gary: Zenker (1912) near Hildesheim, Germany ; and Klebs (1912) near Buiten-
zorg, Java.

Klebs’s (1912) record of the occurrence of this species in the tropical waters
of Java may be held as tentative, since he gives no figures or description. The
change from the cool temperate regions of Finland and Germany to the tropical
waters of Java, about 15° C, might be expected to result in specific differences.

ComParisons.—This: species is closely related to G. palustre and G. viride
in size, form, and habitat, and is one of a small group of fresh-water species,
most. of them possessing brownish or greenish chromatophores and of an
elongated, subovoidal form, about 1.5 transdiameters in length. This species
differs from all others of the group in having bluish green, elliptical, disklike
chromatophores.

Gymnodinium agile sp. nov.
Plate 3, figure 31; text figure Y, 9

DraGnosts.—A minute species with body rounded disklike, its length 1.07
transdiameters, with sinistral apical point; girdle median, without displace-
ment; sulcus extending from girdle to antapex; colorless, with orange green
chromatophores. Length, 28». Pacific off La Jolla, California, July, August.

DescripTion.—The body is rounded in ventral view, flattened dorsoventrally, with broad
apices, its length 1.07 transdiameters at the widest part, its dorsoventral diameter 0.4 of its
transdiameter. The epicone and hypocone are subequal. The epicone is subhemispherical with
the apex displaced to the left as a minute, pointed, finger-like projection bending downward
towards the surface of the body. The length of the epicone is about 0.5 of the total length of
the body. The hypocone is symmetrically hemispherical in ventral view, with the antapex
occasionally notched by the distal end of the suleus.

The girdle is equatorial in position and is without displacement, forming a complete circle
around the body. The furrow is broad, about 0.08 transdiameter, and deep with smooth,

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 185

overhanging borders. The anterior flagellar pore opens at its junction with the suleus, the pos-
terior pore about 1.5 widths of the girdle posterior to the anterior one. The transverse flagellum
traverses about 0.3 of the length of the girdle.

The suleus extends from the girdle to the antapex as a wide, rather deep trough, which widens
at both ends. In some individuals the distal extremity notches the antapex.

The nucleus is ellipsoidal and anteriorly placed. Chromatin strands could not be detected
in its structure. Its major and minor axes are about 0.5 and 0.34 transdiameter in length
respectively.

A sacklike, bright coral-red pusule opens into each flagellar pore. The cytoplasm is clear
and colorless. Minute refractive bodies are numerous in the epicone and absent in the hypocone,
in which part a single large amyloid, or food body, is present. In both hypocone and epiecone
are a few flat, ellipsoidal, orange green chromatophores, comparatively large, and located in the
periphery. <A distinct, double-contoured pellicle surrounds the body. Nutrition is probably
holophytie.

Dimenstons.—Length, 28; transdiameter, 26; dorsoventral diameter, 10;
major and minor axes of nucleus, 14 and 19 respectively.

OccuRRENCE.—The individual figured was taken from the beach sand at La
Jolla, California, July 3, 1917. Others were present in the same material and
in the material examined at a later date. One individual was taken August 13,
0.75 of a mile off La Jolla, in a haul made from 80 meters to the surface.

This form was associated with Amphidinium dentatum, A. corpulentum, and
A. scissum, all typical beach forms. It presents two of the characteristics of
these species in its dorsoventrally flattened body and chromatophores.

CoMPARISONS.—This species resembles G. hamulus in the possession of a
sinistral apical point, but differs from it in its larger size, and absence of striae.
The point is suggestive of the extension of the sulcus to the apex.

Gymnodinium amphora sp. nov.
Plate 3, figure 26; text figure AA, 6

DraGnosis.—A large species with stout ovoidal body, its length 1.58 trans-
diameters; girdle premedian, displaced nearly twice its own width; sulcus ex-
tending from apex to antapex; color green yellow. Length, 151". Pacific off
La Jolla, California, August.

Description.—The body is large, ovoidal, nearly circular in cross-section, widest anteriorly
at the girdle and tapering posteriorly, with broad apices, its length 1.58 transdiameters at the
widest part. The hypocone greatly exeeeds the epicone in size, being 0.45 of its own length
longer than the epicone. The epicone forms an asymmetrical, broad, rounded, cap-shaped part
of the body with a length on the left and right sides of 0.33 and 0.36 of the total length of the
body respectively. It forms a cone of nearly 90°. The apex is broad and widely notched near
the end of the suleus. The hypocone is more symmetrical than the epicone, elongate, rounded
conical (30°), with the antapex much narrower than the apex, but without suleal notch.

The girdle is premedian in position and passes around the body in a slightly descending left
spiral direction, with a displacement of about twice its own width. The furrow is wide, about
0.05 transdiameter, and deeply imbedded with overhanging, slightly undereut borders. The
proximal and the distal ends join the suleus at distances from the apex of respectively about

186 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

0.33 and 0.36 of the total length of the body. The suleus begins at the apex and extends poster-
iorly in an almost straight line to near the antapex. It lies in a rather wide shallow trough
with rounded sides which fade out in the apical regions. The anterior flagellar pore is slightly
below the proximal junction of the girdle and suleus. The posterior pore opens at about 0.58
of the distance between the anterior pore and the antapex.

The nucleus is spherical and located in the posterior third of the body. Its axis is about
0.27 transdiameter in length. A long sacklike pusule opens into the anterior flagellar pore.
The cytoplasm is clear and finely granular, and filled with metabolic products, evidences of
holozoie nutrition. In the central part of the body was a large, brownish food mass, obscured
by a great mass of dark, refractive granules. Radiating out from this were long slender blue
green rodlets, or radial canals. Smaller groups of granules filled the remaining central and
anterior regions of the body, with a few small bodies, yellow ochre in color. In the antapical
region were several large vacuoles filled with fluid, colored salmon pink like the pusule.

This species, like G. dogicli, has a distinet ectoplasmic region, composed of a thin layer
surmounted by an alveolar layer, the outer portions of the alveoli being rounded and giving a
roughened appearance to the surface of the body. This layer is appreciably thicker in the
antapical region and is a striking feature of the body in a general view. The color of the
organism is pale turquoise green shading to deep yellow on the right side of the hypocone, and
slightly diffused throughout the cytoplasm, but with a greater concentration in the peripheral
region. The surface exhibited no striae or other markings.

Divensions.—Length, 15; transdiameter, 95; axis of nucleus, 27+.

OccURRENCE.—A single individual was taken on August 13, 1917, with a
No. 25 silk net, 0.75 of a mile off La Jolla, California, in a haul from 80 meters
to the surface and in a surface temperature of 21°9 C,

Comparisons.—This is one of the most highly differentiated species of
Gymnodinium, as shown in its highly developed ectoplasm, and belongs with
the subgenus Pachydinium. In its cytoplasmic structure, coloring, and size it
stands very close to G. dogieli and G. pachydermatum (fig. AA, 8,5), but differs
greatly from them in its relative proportions and arrangement of girdle, having
the shortest epitheca of the three and an anterior suleal notch.

Gymnodinium attenuatum sp. nov.
Text figure Y, 12

Dracnosts.—A small species with ovate fusiform body, apices acute, com-
pressed laterally, its length 2.24 transdiameters; girdle premedian, displaced
less than its own width; sulcus extending from apex to near antapex; surface
finely striate. Length, 65”. Pacific off La Jolla, California, June, July.

DescripTion.—This is a small species with ovate body sharply pointed at both ends, and
compressed laterally, its dorsoventral diameter equaling 1.17 transdiameters and its length 2.24
transdiameters. It is slightly asymmetrical with the ventral face having a greater convexity
than the dorsal face. The epicone is nearly 0.5 shorter in length than the hypocone. The
basal portion of the epicone is rotund, tapering anteriorly to a sharp, slender point. The apex
is somewhat excentric, being thrown dorsad by the greater slope of the ventral face. Its length
is about 0.3 of the total length of the body. The length of the hypocone is about 0.66 of the
total length of the body. It is rounded anteriorly and tapers to a long, slender antapex.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 187

The girdle is premedian in position, lying at about 0.3 of the total length of the body from
the anterior end. It is narrow, shallow, and is displaced about half its own width. The anterior
flagellar pore opens at its proximal junction with the suleus, and the posterior pore midway
between the girdle and antapex. The narrow, shallow suleus invades the epicone to the apex.
Below the girdle it extends posteriorly in a straight line, traversing about 0.7 of the distance
from the girdle to the antapex.

The nucleus is elliptical in outline and centrally located with its major axis coinciding with
the long axis of the body. Its chromatin contents could not be analyzed. Its major and minor
axes are about 0.6 and 0.4 transdiameters in length respectively. The cytoplasm is clear with
no large inclusions, but containing a number of oil globules and small, subspherical or irregular
bodies superficially arranged. The surface is striate with equidistant, longitudinal striae about
equal in number on both epicone and hypocone and about 20 at the girdle across the ventral face.

Divenstons.—Length, 65-78; transverse diameter, 29-38; dorsoventral
diameter, 344; axes of nucleus, 17# and 12+.

OccuRRENCE.—This species was first taken June 28, 1904, with a No. 20 net,
in a haul 10 miles off La Jolla, California, from 120 meters to the surface. It
was again found July 5, at the same distance offshore with the same apparatus,
in a haul from a depth of 240 meters to the surface. On July 7 of the same year
it was taken 11 miles off La Jolla in a surface haul.

Comparisons.—This species belongs to the subgenus Lineadinium, having
the thin periplast and striate surface of that group, but is unique in its lateral
compression and acute apices.

Gymnodinium auratum sp. nov.
Plate 2, figure 20; text figure Y, 13

Dracnosis.—A small species with ovoidal body, its length 1.44 transdiame-
ters; epicone conical; girdle submedian, displaced slightly more than its own
width; sulcus extending from apex to antapex; color old gold. Length, 62+.
Pacific off La Jolla, California, August.

Description. —The body is broadly ovoidal, nearly circular in cross-section, broadly rounded
posteriorly, conical anteriorly, its length 1.44 transdiameters at the girdle, the widest part. The
length of the epicone and hypocone are subequal, but, owing to its rotundity, the hypocone
exceeds the epicone in volume. The epicone is conical, about 70°, with a narrowly blunt apex.
It has a length on the left and right sides of 0.48 and 0.54 of the total length of the body
respectively. The hypocone is broadly rounded, with smooth antapex.

The girdle is submedian in position, its proximal and distal ends having a distance from the
apex of 0.43 and 0.54 of the total length of the body respectively. It is wide, about 0.09 trans-
diameter, and deeply impressed with smooth lips. Its course around the body is that of a left
descending shallow spiral, with its distal end displaced posteriorly slightly more than its own
width. The sulcus is a shallow, narrow channel, its width about 0.3 of the width of the girdle.
It extends from near the apex in a slightly sinuous course posteriorly to near the antapex. The
anterior flagellar pore opens at the proximal junction of the girdle and sulcus, the posterior
pore about two widths of the girdle posterior to the distal junction.

The nucleus is a large, ellipsoidal body found on the left side of the hypocone. It is filled
with fine, moniliform, chromatin strands arranged parallel to its long axis, which is slightly
oblique to the major axis of the body. Its major and minor axes are about 0.65 and 0.4 trans-
diameter in length respectively.

188 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Small, club-shaped pusules open into each flagellar pore. The cytoplasm was unusually free
from cell inclusions such as food bodies, vacuoles, ete. A small, irregular, dark green mass was
found close beside the nucleus and farther anteriorly, another, slightly larger, of a neutral grey
with a dark border. The cytoplasm is finely granular. The general color is old gold, quite deep
posteriorly, shading to pale king’s blue at the anterior end, with tones of light green and pearl
erey through the girdle region. No striae or other markings could be detected on its surface.
A thin hyaline eyst somewhat larger than the body, and closely following its contour, enclosed
the organism.

DrmMenstons.—Length, 62; transdiameter, 43; axes of nucleus, 28 and 18;
length of cyst, 66.

OccuRRENCE.—A single individual was observed August 20, 1917, from a
haul made 0.75 of a mile off La Jolla, California, from 80 meters to the surface,
and in a surface temperature of about 22° C.

CoMPARISONS.—This species, because of the comparative simplicity of its
organization and lack of surface markings, falls within the subgenus Gymno-
dinium sensu strictu. Its coloring suggests that of G. amphora (fig. AA, 6),
but it differs greatly from that species in all other respects. In proportions
it approaches rather distantly some of the biconical species of the subgenus
Lineadinium (fig. Y), but lacks the striae which characterize that subgenus.
It is nearest G. violescens sp. noy. (fig. X, 11), but is wholly different in color,
has less displacement of girdle, and a fuller hypocone.

Gymnodinium aureum sp. nov.
Plate 1, figure 5; text figure Y, 3

DraGnosis.—A medium sized species with subovoidal body pointed poster-
iorly, its length 1.84 transdiameters; girdle premedian, displaced twice its own
width; sulcus extending from near apex to antapex; surface striate; color
strontium yellow. Length, 834. Pacific off La Jolla, California, July.

DescripTtion.—The body is ovoidal, subtruncate-acuminate anteriorly, tapering to a slender
point posteriorly, widest through the epicone, its length 1.84 transdiameters at the widest part
and its dorsoventral diameter 0.85 transdiameter. The hypocone exceeds the epicone in size,
being longer by 0.18 of its length. The epicone is conical in outline (70°). Its apex is truneate-
acuminate with a median and two lateral elevations on the summit formed by two parasagittal
creases across the apex. Its length is about 0.39 of the total length of the body, with the right
side extending posteriorly in a slender point with a length of 047 of the total length. The
hypocone is longer, less symmetrical than the epicone and is drawn out distally to a slender,
pointed, ventrally flexed antapex. It has a width at the girdle equal to the width of the epicone,
but is much narrower posteriorly.

The girdle is premedian in position, its proximal end meeting the suleus at a distance from
the apex of 0.39 of the total length of the body. It passes around the body in a nearly trans-
verse direction for about 0.8 of its course, the latter part turning posteriorly so that the distal
end is displaced about twice its own width. The furrow is wide, about 0.08 transdiameter, its
distal end narrowed to less than half that width, and is deeply impressed with smooth, over-
hanging borders. The suleus is somewhat variable in its length. It may invade the epicone a
short distance only or may reach the neighborhood of the apex. The furrow is deep, varies

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 189

greatly in width, being usually wide at the girdle and at the posterior end of its course which is
near the antapex. The anterior flagellar pore opens at the junction of the proximal end of the
girdle and the suleus and the posterior pore at their distal junction.

The nucleus is a large, ellipsoidal body located anterior to the equatorial plane. It is filled
with fine, moniliform chromatin strands and shows a distinct double-contoured membrane sur-
rounding it. Its major and minor axes are 0.46 and 0.52 transdiameter respectively. The
eytoplasm is coarsely granular and was quite free from food bodies and vacuoles in the specimens
examined. The surface is striate with longitudinal, equidistant blue-green striae composed of
linear series of short broken lines. These are about the same number on both epicone and
hypocone, approximately 16 across the ventral face. The color of the organism is a clear
strontium yellow, diffused through the cytoplasm. It is probably holozoic in its nutrition.

Divenstons.—Length, 83; transdiameter, 45; dorsoventral diameter, 39+;
major and minor axes of nucleus, 134 and 11¢ respectively.

OccuRRENCE.—This was first observed July 11, 1906, in a haul with a No. 20
net, 2 miles off La Jolla, California, from 155 meters to the surface and in a
surface temperature of 20°9 C. It was found July 9, 1917, in a haul with a
No. 25 net, 4 miles offshore, from 80 meters to the surface and in a surface
temperature of 19°8 C.

Comparisons.—This species bears a strong resemblance to Gymnodinium
helveticum Penard. Penard’s (1891) species, however, is a fresh-water form
from Lake Geneva, Switzerland. Our species is probably the marine repre-
sentative of the same group. Its size and proportions differ somewhat from
those of G. helveticum and it has a greater displacement of the girdle. It be-
longs to the subgenus Lineadinium, but, aside from G. helveticum, there are no
other species closely resembling it.

Gymnodinium bicaudatum Pavillard
Text figure BB, 9

Gymnodinium bicaudatwm Payillard (1905), p. 47, pl. 3, fig. 5.

This organism was described by Pavillard (1905) from the Gulf of Lyons
and seems to have suggestions in its symmetry of the characteristics of the
thecate genus Hetcrodinium Kofoid. The data given are not sufficient to place
it in Gymnodinium, or to define its specific characters. The two posterior
projections are quite unlike anything in the unarmored dinoflagellates. It may
be a theeate form recently escaped by exuviation of the skeleton and therefore
temporarily non-thecate. The possibility of approaching division or of an
antapical vent following ejection of food balls in an unarmored species is not
precluded as an explanation of the bifurcated postmargin.

190 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Gymnodinium biciliatum Ohno
Text figure X, 14
Gymnodinium biciliatum Ohno (1911), pp. 77-91, pl. 1, figs. 1-37.

DiaGnosis.—A minute species with broadly ellipsoidal body, its length 1.31
transdiameters; girdle without displacement; sulcus short on epicone, extending
to near the antapex on hypocone; color yellow brown. Length, 22. Fresh-
water ponds in the Botanical Gardens at the Imperial University at Tokyo,
Japan.

DescripTIoON.—The body is broadly ellipsoidal with broad rounded apices, and its length is
1.31 transdiameters at the widest part. The hypocone exceeds the epicone in size, its length
being greater by 0.2. The epicone has a length of about 0.4 of the total length of the body.
The hypocone is subhemispherical posteriorly, with broad apex.

The girdle is premedian in position, its distance from the apex being 0.4 of the total length
of the body. The furrow is wide, 0.09 transdiameter, and deeply impressed, with high rounded
borders. The suleus is a short shallow trough, its length about twice the width of the girdle.
The longitudinal and transverse flagella arise in close proximity to each other at the junction of
girdle and suleus. Two longitudinal flagella are described and figured by Ohno (1911), hence
the specific name.

The nucleus is not figured by him, but it evidently lies in the dark mass near the center of
the body. Numerous oil droplets are contained within the cytoplasm. The color is yellow brown.
Chromatophores appear to be centrally massed ellipsoidal bodies of yellowish brown eolor. At
eyst formation the body rounds up within an irregularly lobed, thorny, cellulose eyst.

DiMeEnstons.—Length, 22.2 (20.6-25) ; transdiameter, 16.9 (12-21r).

OccuRRENCE.—Figured by Ohno (1911) from fresh-water ponds in the
Botanical Gardens of the University at Tokyo, Japan, where it was most
abundant during the winter months.

Discusston.—The presence of three flagella in this form, two of which are
longitudinal, if valid, is without parallel in the Dinoflagellata, and this fact
raises the question of the correctness of Ohno’s interpretation. The appearance
shown in his figure 5, plate 1, is one commonly seen in living Gymnodinium.
The actively moving flagellum swings through an are that is fairly constant
and forms a cone of rotation, the sides of which are strongly marked and give
the appearance of two very distinct Hagella. Watching these until the move-
ment slows down, however, the observer sees them resolve into a single flagellum.
The presence of three flagella in the stained specimen finds its parallel in condi-
tions during the mitotic period in other flagellates. In most if not all flagellates
the motor organelles are the first to exhibit signs of division, and this not infre-
quently results in a precocious outgrowth of the new flagella. In the material
studied by Obno rapid multiplication was evidently taking place, both in
encysted and free swimming forms. The central part of the body is figured
only as a dark mass and hence offers no conclusive evidence either way for the
solution of this problem. It is evident, however, that Ohno’s interpretation

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 191

can not be accepted even with reservations until the subject has received further
investigation. It is highly probable that this species has the equipment of
flagella normal to the Dinoflagellata.

G. biciliatum belongs to the subgenus Gymnodiniwm.

Compartsons.—In size, proportions, and color this species approaches G.
bogoriense Klebs and G. aeruginosum, though not the figure selected by Schilling
(1913) as typical. It is somewhat smaller than the average, 22.2u, and smaller
than G. aeruginosum, which Schilling (1913) states to have a length of 33-34,
and is also relatively stouter. Cyst formation has some features in common
in the two species, but the rigid irregularly spinose cyst of Ohno’s species is
apparently different from the imperfectly known cyst of G. aeruginosum. Its
dimensions are very close (22.2« by 16.9) to those of Klebs’s (1912) species
(224 by 17), and the two may prove on full examination of chromatophores
and cysts to be identical. If so Ohno’s (1911) name has priority over that of
Klebs: (1912).

Gymnodinium bicorne sp. noy.
Plate 2, figure 14; text figure BB, 10

DraGnosis.—This is a small species with subreniform body, its length 2.86
dorsoventral diameters; girdle submedian, displaced twice its own width;
sulcus extending from near apex to antapex; color vellowish grey. Length, 63+.
Pacifie off La Jolla, California, July.

DeEscripTion.—The body is slender ellipsoidal, with broad apices, subreniform in lateral view,
its dorsoventral diameter slightly greater than its transdiameter, its length 2.86 dorsoventral
diameters at its widest part. The epicone and hypocone are subequal in length. The epicone
is rounded conical in ventral view with broad apex; in lateral view the dorsal side is convex, the
ventral coneave posteriorly, convex anteriorly. It has a length on the left and right sides of
0.42 and 0.54 of the total length of the body respectively. The hypocone is somewhat narrower
posteriorly than the corresponding part of the epicone. The antapex is rounded without suleal
notch.

The girdle is submedian in position, with a distance from the apex at its proximal and distal
ends of 0.42 and 0.54 of the total length of the body respectively. The furrow has a width of
about 0.09 transdiameter and is deeply impressed with smoothly rounded borders. Its course
is that of a descending left spiral, with its distal end displaced posteriorly about twice its own
width.

The suleus is a narrow trough extending from near the apex to the antapex in an almost
straight line. Its greatest width is found in the intercingular area, becoming narrower on the
epicone and hypocone and fading out near both apices. The anterior flagellar pore opens at the
proximal junction of the girdle and sulcus, the posterior pore a short distance below the distal one.

The nucleus is an ellipsoidal body lying in the central plane with its major axis parallel to
the major axis of the body. It is filled with moniliform chromatin strands. Its major and
minor axes are about 0.86 and 0.36 transdiameter in length respectively.

The plasma is finely granular and contains numerous small green granules and dark refractive
bodies. An irregular, sacklike pusule opens into the anterior flagellar pore. The color of the
cytoplasm is pearl grey with yellow splashes through it that may be chromatophores. This

192 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

organism was enclosed in a crescent-shaped double-contoured eyst much more arcuate than that
of G. lunula and longer from tip to tip. Both flagella were active while under observation,
producing a slight rotation of the body in the cyst.

Divensions.—Length, 63; dorsoventral diameter, 22+; axes of nucleus, 19
and 8; length of evst, 105z.

OccuRRENCE.—This was taken in a surface haul at the end of the pier at the
Biological Station at La Jolla, California, July 19, 1917.

CoMPARISONS.—This species greatly resembles an individual shown in
Dogiel’s (1906) figure 20, plate 1, which he includes in Gymnodinium lunula.
The shape of the body is shghtly different in the two forms included by Dogiel,
the one referable to G. bicorne having a greater convexity of the dorsal and
concavity of the ventral surfaces. The differences are probably adequate for
specific distinction. Both Dogiel’s figure 20 and our individual differ widely
from G. Junula, in size and shape of the body as well as in their relative pro-
portions. The shape of the enclosing cyst is apparently the only ground for
its inclusion by Dogiel with those of G. lunula, and even this shows distin-
guishing characteristics.

Gymnodinium bifurcatum sp. nov.
Text figures AA, 2, 3

Driacnosis.—A_ large species with a peculiarly laterally flattened body,
broadly ovoidal in side view, double funnel-shaped in ventral view, its length
1.07 dorsoventral diameters; hypocone dorsoventrally deeply bifureate by the
sulcus; girdle submedian, displaced one width; sulcus short and very deep on
hypocone; color, pinkish grey. Length, 1254. Pacific off La Jolla, California,
August.

Description.—The body is broadly ovoidal in lateral view, widest anteriorly in the posterior
epicone, strongly laterally compressed, especially on each side of the girdle region. Its length
is 1.07 dorsoventral diameters at the widest part. Its transdiameter through the girdle region
is about 0.56, through the midpart of the epicone about 0.12, and of the hypocone 0.15 of the
dorsoventral diameter. The epicone and hypocone are subequal in length, but its broader dorso-
ventral diameter gives to the epicone a somewhat greater size. The epicone is subsemicireular
in outline viewed laterally, with a very slight asymmetry on the ventral side. In ventral view
it is inverted funnel-shaped, flaring widely in the posterior third of its length. Its length on
the left and right sides is about 0.53 and 0.50 respectively of the total length of the body. The
apex is smoothly rounded. The hypocone has the shape of a broad, rounded cone of about 70°
in lateral view, with broad, rounded antapex. In ventral view it is bifureate funnel-shaped,
the cleft formed by the suleus extending nearly its entire length to within a girdle’s width of
the girdle itself.

The girdle is submedian, the distance of its proximal and distal ends from the apex being
0.53 and 0.50 respectively of the total length of the body. It passes around the body with only
a slight posterior deviation from a transverse direction in the distal fourth of its course, with
a displacement of about its own width. The furrow is wide, about 0.04 transdiameter in width,
and deeply impressed with smooth borders, of which the anterior one is prolonged into a thin,

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 193

finlike extension which covers about 0.7 of the width of the girdle. The transverse flagellum
traverses nearly its entire length. The suleus does not invade the epicone. On the hypocone it
sinks through the body to the dorsal surface, dividing the hypocone into two subequal extensions
or flaps (text figure AA, 3). The anterior flagellar pore opens at the proximal end of the girdle,
the posterior pore slightly below the distal end.

The nucleus is an ellipsoidal body located in the central part of the organism, with its long
axis lying in a dorsoventral plane. Its major and minor axes are about 0.39 and 0.24 dorso-
ventral diameter respectively.

The cytoplasm is unusually clear and transparent, the granulations being too fine to be easily
detected. The ectoplasm is not marked off by a clear-cut line as in G. dogieli, yet it seems to
have a slightly different consistency from that of the endoplasm and is more homogeneous. Below
this layer in the epicone is a zone filled with small vacuoles. The remainder of the cytoplasm
showed no cell inclusions. The surface of the hypocone is marked by a few lines, three on one
face, which fade out near the girdle and the antapex. On the epicone these are more numerous
and are shorter, being radially arranged around the margin in lateral view. The color of the
organism is pinkish grey, deeper on the epicone and through the girdle region, though this latter
may be due solely to the greater thickness of the body at that plane.

Diwvenstons.—Length, 1254; transdiameter at girdle, 67; dorsoventral
diameter, 1094; axes of nucleus, 60# and 30+.

OccurRRENCE.—This was found August 6, 1917, in a haul with a No. 25 silk
net. 4 miles off La Jolla, California, in a haul from 60 meters to the surface and
in a surface temperature of 21°2 C.

CoMPARISONS.—This organism is a baffling one in attempting to trace out
its affinities and even some details of its structure. Owing to its peculiar shape
and delicacy of organization a camera drawing could not be obtained of the
ventral view, the figure given in text figure AA, 3, being made free-hand and
its measurements checked up with the camera sketch afterwards. In ventral
view it greatly resembles a Peridinium escaped from its theca, but a lateral
view serves only to emphasize the very great differences between it and any
known Peridinium. In its lateral compression it recalls Amphidinium sulcatum
sp. nov. (fig. U, 26), but differs greatly in all other details of its structure from
that species. Its internal cytoplasmic organization is relatively simple, its
thickened periplast, however, placing it in the subgenus Pachydinium. In its
coloring it is not unlike G. abbreviatum sp. nov. (fig. Z, 7) in the same subgenus.

Gymnodinium bogoriense Klehs
Text figure X, 10
Gymnodinium bogoriense Klebs (1912), pp. 397, 419, 439, fig. 7e, d.
G. bogoriense, Cavers (1913), p. 182, fig. 9..
G. bogoriense, Pascher (1916), p. 127.

DraGnosis.—A minute species with ovoidal, dorsoventrally flattened body,
its length 1.3 transdiameters; girdle without displacement; sulcus extending
from girdle to antapex. Length, 234. Fresh-water ponds in the Botanical
Garden at Buitenzorg, Java.

194 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Description.—The body is stout ovoidal in ventral view, flattened dorsoventrally, its length
1.3 transdiameters at the widest part and its dorsoventral diameter 0.75 transdiameter. The
epicone and hypocone are subequal in length, the greater width of the hypocone giving it a
slightly greater volume. The epicone is subhemispherical in outline, its length about 0.43 of
the total length of the body. The hypocone is more symmetrical than the epicone, broad and
rounded posteriorly.

The girdle is slightly premedian in position and forms a complete circle around the body.
The furrow is wide, about 0.2 transdiameter, and rather deeply impressed. The suleus extends
from the girdle to the antapex as a wide furrow which is slightly deflected to the left posteriorly.
The flagellar pores are not indicated in Klebs’s (1912) figures.

The nucleus is a small, spheroidal body near the central part of the cell. Its diameter is
0.3 transdiameter of the body. A number of radially arranged, stout rod-shaped bodies are
found in the cytoplasm similar to the chromatophores in G. rotundatum, but their function is
not mentioned in the description of Klebs (1912).

Divensions.—Length, 20-24; transdiameter, 16-18; dorsoventral diameter,
12; diameter of nucleus, 6+.

OccuRRENCE.—This species was figured by Klebs (1912) from fresh-water
ponds in the Botanical Garden at Buitenzorg, Java.

Comparisons.—This species greatly resembles G. rotundatum Klebs (1912),
differing from it, however, in being flattened dorsoventrally and of somewhat
smaller size, as well as being, in so far as known, a tropical species. Their
description in the same paper by the veteran protistologist and investigator of
the Dinoflagellata is an adequate guaranty of their specific distinctions. Its
resemblance to Ohno’s (1911) G. biciliatum has already been discussed.

Gymnodinium canus sp. nov.
Plate 4, figure 41; text figures Z, 1, 2

DraGnosis.—A large species with asymmetrical ovoidal body, its length 1.72
transdiameters, epicone sloping anterodorsally, with an apical horn; girdle sub-
median, displaced 0.18 transdiameter; sulcus extends from apex to antapex;
surface coarsely striate; color greenish grey. Length, 1124. Pacific off La Jolla,
California, August.

Description.—Body large, asymmetrically ovoidal in lateral view, widest posteriorly, its length
1.72 transdiameters at the widest part, which is in the anterior third of the hypotheca. The
ventral aspect presents an approximately symmetrical outline. In lateral view it is seen that
the dorsoventral diameter, which equals the transdiameter posteriorly, in the epicone diminishes
towards the apex which is eccentrically placed near the dorsal face of the body. The ventral
surface forms an angle of about 50° with the transverse plane for about 0.7 of the height of
the epicone, beyond which the slope approaches the transverse direction again for a short
distance, then ascends longitudinally to the contracted, obliquely truncate and notched apex.
The dorsal face of the epicone forms a slightly convex line from girdle to apex. Owing to the
diminished dorsoventral diameter the epicone is considerably smaller in size than the hypocone,
though their relative lengths are about the same. The length of the epicone on the left and
right sides is about 0.43 and 0.53 respectively of the total length of the body. In ventral view
it is dome-shaped with rounded sides; the apex is contracted and elongated with a slight twist

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 195

towards the right side of the body and deeply notched by the anterior end of the suleus. The
hypocone is slightly asymmetrical with the left side more convex than the right. It is bifureated
at the posterior end by the deep excavation of the suleal notch which reaches through and cuts
the dorsal surface of the body.

The girdle is submedian in position, its proximal end joining the sulcus at a distance from
the apex of 0.43 and its distal end 0.53 of the total length of the body. It follows a descending
left spiral course around the body, displacing its distal end posteriorly 0.18 transdiameter. The
furrow is wide, about 0.09 transdiameter, and deeply impressed with smooth, overhanging
borders. The suleus extends from the apex to the antapex in a slightly sinuous line, and deeply
notches both apices. The trough is narrow and shallow anteriorly, but expanding laterally and
sinking deeper into the body posterior to the girdle until it nears the antapex where it reaches
through and cuts the dorsal surface, bifurcating the posterior end of the body. The anterior
flagellar pore opens at the proximal junction of the girdle and sulcus, the posterior pore some-
what behind the middle point between the distal junction and the antapex.

The nucleus is a large, ellipsoidal body in the center of the hypocone. In the specimen
examined its nuclear structure could not be determined with any degree of accuracy. Its major
and minor axes are about 0.49 and 0.3 transdiameter rsepectively. A small sacklike pusule
opens into the posterior flagellar pore. None was noted at the anterior pore.

The cytoplasm is coarsely granular, somewhat dense, with closely packed vacuoles filling
the entire central part of the body. A mass of minute, highly refractive granules lies in the
region of the anterior flagellar pore. The cytoplasm and most of the vacuoles are grey in color,
others showing a faint tinge of salmon pink. The surface is covered with longitudinal, equi-
distant, blue-green striae, approximately equal in number on both epicone and hypocone. Minute
blue-green spherules are profusely scattered through the peripheral layer between the striae.

Dimensions.—Length, 112; transdiameter, 65“; major and minor axes of
nucleus. 32 and 20 respectively.

OccuRRENCE.—A single individual was taken August 17, 1917, with a No. 25
net, 0.75 of a mile off La Jolla, California, in a haul from 80 meters to the
surface and in a surface temperature of 22°5 C.

Comparisons.—This species, while not exhibiting the distinct ectoplasmic
differentiations of G. dogicli, vet possesses a periplast of firmer consistency than
any member outside of the subgenus Pachydinium, and it is therefore placed
in that group. It stands near G. costatum, differing from it in its proportions
and in the contracted shape of the epicone. In the marked asymmetry of its
epicone it stands apart from all other species of Gymnodinium, though the
lateral displacement of the apical point in such species as G. hamulus sp. nov.,
G. agile sp. nov., and G. vestifict Schiitt (fig. Y, 5, 9, 10) is indicative of asym-
metrical tendencies.

Gymnodinium carinatum Schilling
Text figure X, 34

Gymnodinium carinatum Schilling (1891), p. 278, pl. 10, fig. 12.

G. carinatum, Mez (1898), p. 216.

G. carinatum, Lemmermann (1900), p. 116; (1903), p. 260.

G. carinatum, West (1916), fig. 36a.

Draanosis.—A minute species with ellipsoidal body, its length 1.5 transdi-

ameters; girdle without displacement; sulcus extending from girdle to antapex,

196 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

keel at its left; brownish chromatophores. Length, 39.74. In swamps near
Neudorf, Switzerland.

DescripTION.—The body is ellipsoidal, widest at the middle and taperimg anteriorly, its
length 1.15 transdiameters. The epicone and hypocone are subequal in length. The epicone
is subeonical with broad, blunt apex. Its length is about 0.5 the total length of the body. The
hypocone is slightly narrower near the girdle and broader posteriorly than the corresponding
parts of the epicone, with truncate or notched antapex.

The girdle forms a complete circle near the middle of the body, its distance from the apex
being 0.5 of the total length of the body. It has a width of 0.1 transdiameter and is deeply
impressed with rounded borders. The suleus extends from the girdle to the antapex. Its left
border is guarded by a well developed list or projecting keel. The transverse flagellum arises
at the junction of the girdle and suleus and the posterior flagellum slightly below.

The nucleus is not figured by Schilling (1891). The central part of the body is occupied
by a few relatively large, disklike, light to dark brown chromatophores.

Divensions.—Length, 39.7; transdiameter, 34.54, as given in the text
(Schilling, 1891), but the careful measurement of Schilling’s drawings (1891,
1913) gives a width of 264. This size has been used in finding the proportions
given in the description above.

OccuRRENCE.—Figured by Schilling (1891) from fresh-water swamps and
ponds near Neudorf, Switzerland.

CoMParisons.—This species presents a striking similarity to G. aeruginosum,
G. palustre, and G. viride in size and proportions. It differs from them, how-
ever, in its shortened dorsoventral diameter and in the list on the left border
of the suleus. It belongs to the subgenus Gymnodinium and with the small
group of fresh-water species in that subgenus, comprising G. bogoriense, G.
rotundatum, G. palustre, G. uberrimum, G. viride, and G. aeruginosum.

Gymnodinium cinctum sp. nov.
Plate 7, figure 75; text figure X, 28

DraGnosis.—A minute species with ovoidal body, its length 1.18 transdiam-
eters; girdle premedian, displaced nearly twice its own width; sulcus short;
ellipsoidal yellow ochre chromatophores. Length, 254. Pacific off La Jolla,
California, July.

DescrrpTioN.—This species has a minute, broadly ovoidal body, rounded at both apices,
widest posteriorly, its length 1.18 transdiameters at the widest part. The hypocone greatly
exceeds the epicone in size, having a greater width and exceeding it in length by 0.15 of its own
length. The epicone is subconical (about 70°) with rounded, blunt or slightly pointed apex.
Its greatest transdiameter is 0.63 transdiameter of the hypocone. It has a length on the left and
right sides of 0.34 and 0.53 respectively of the total length of the body. The hypocone is midway
between spherical and hemispherical in outline with broad, rounded antapex.

The girdle is premedian in position, its proximal end meeting the suleus at a distance from
the apex of 0.34 and its distal end 0.53 of the total length of the body. It sweeps around the
body in a descending left spiral direction, displaced posteriorly at its distal end nearly twice its
own width. The furrow is relatively wide, about 0.13 transdiameter, and deeply impressed with

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 197

smooth rounded borders. The sulcus is short on both epicone and hypocone, broad anteriorly
and narrowing to a point posteriorly. In several individuals it extended posteriorly to the
antapex. The anterior flagellar pore opens at the proximal junction of the girdle and suleus,
the posterior pore slightly below the distal junction.

The nucleus is ellipsoidal, its major axis coinciding with the major axis of the body, and is
centrally located. Large monliform chromatin threads followed its major axis. Its major and
minor axes are 0.77 and 0.54 transdiameter respectively.

A very large, irregular, sacklike pusule opens into both flagellar pores. The cytoplasm is
clear and without visible granulations or color. A very few green oil droplets were present.
Numerous ellipsoidal, diskike chromatophores are seattered through the peripheral layer. These
have a general tone of yellow ochre. The organism is closely invested with a thin-walled, hyaline
eyst which follows the contour of the body.

Dmvenstons.—Lenegth, 26“; transdiameter, 22; axes of nucleus, 17 and 12+.

OccuURRENCE.—It was first met with July 21, 1906, at La Jolla, California,
in a haul made with a No. 20 net from 565 meters to the surface. One indi-
vidual was taken July 5, 1917, with a No. 12 silk net, 6 miles off La Jolla, in a
haul from 80 meters to the surface in a surface temperature of 21°4 C. It was
found again July 23, at approximately the same place, with the same apparatus
and in a surface temperature of 20°2 C,

CoMPARISONS.—This species shows some shght resemblances to Gymnodinium
marinum Kent. It differs from that species, however, in its proportions, its
smaller epicone, reduced sulcus, and in its possession of yellow ochre chromato-
phores. No food masses were observed in the cytoplasm and the presence of
chromatophores would suggest a holophytic mode of nutrition. Saville-Kent’s
(1880-82) species is holozoic. He observed it actively feeding on minute flagel-
lates in the same culture. It belongs in the subgenus Gymnodinium.

Gymnodinium coeruleum Dogiel
Text figure Z, 4

Gymnodinium coeruleum Dogiel (1906), pp. 35, 36, 40, pl. 2, figs. 46-47.
G. coeruleum, West (1916), p. 52.

Diacnosis.—A rather large species with body subellipsoidal, its length about
2 transdiameters; epicone and hypocone subequal approaching spheroidal form ;
girdle submedian, displaced 0.28 transdiameter, sulcus extending from near the
apex to the antapex; surface striate; color, cornflower blue. Length, 115r.
Mediterranean Sea off Naples, June (?).

DescrirTION.—The body is stout subellipsoidal with broad apices, nearly circular in cross-
section, its length about 2 transdiameters at the widest part. The epicone and hypocone are
subequal and both are broadly rounded. The epicone is rounded with hemispherical apex. It
has a length on the left and right sides of about 0.4 and 0.5 respectively of the total length of
the body. The hypocone is somewhat less symmetrical than the epicone and a trifle more
elongated and deeply notched at the antapex by the distal end of the sulcus.

The girdle joins the suleus proximally at a distance from the apex of about 0.4 and distally
0.5 of the total length of the body. It follows a descending left spiral course about the body,

198 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

displaced posteriorly 0.28 transdiameter. The suleus rises on the epicone near the apex and
passes posteriorly in a sinuous line to the antapex. Near the posterior part it sinks deeply into
the body in a wide depression and forms a deep notch on the ventral face of the antapex. The
flagella and pores were not observed by Dogiel (1906).

The nucleus is an ellipsoidal body in the middle of the hypocone, filled with coarse, chromatin
strands and three large masses of chromatin. Its major and minor axes are 0.48 and 0.37 trans-
diameter respectively. Brownish food masses were present in the anterior part. The surface
is striate with longitudinal equidistant lines or ribs with slight depressions between them. On
each side of the ribs, serially arranged, are small, oval platelike chromatophores, cornflower blue
in color.

- FO

Dimenstons.—Length, 107-115; transdiameter, 55-58; axes of nucleus, 28
and 20+.

OccuURRENCE.— Figured by Dogiel (1906) from the Mediterranean off Naples.
Two individuals were taken by him, one from a surface haul, the other from a
depth of 50 meters. It was taken frequently in the plankton off La Jolla,
California, in the summer of 1906 during an outbreak of red water caused by
Gonyaulax.

CoMPaARIsON.—This species has the same definite ectoplasm as that found in
G. gracile, but not so highly differentiated as that in G. pachydermatum. It
stands alone among the Dinoflagellata in its superb cornflower-blue coloring.
A faint bluish tinge is sometimes seen in G. gracile, otherwise this color is
entirely absent in all other species thus far described. Its thickened periplast
places it in the subgenus Pachydinium, but its color isolates it. Structurally
it is nearest G. wilczeki Pouchet (fig. Z, 8), a smaller stouter species with more
deeply incised postmargin, and greater differentiation of epicone and hypocone.

Gymnodinium conicum nom. sp. noy.
Text figure X, 27
Gymnodinium viridis Lebour (19176), p. 189, fig. 4.

DraGnosis.—This is a small species with subovoidal body, its length 1.86
transdiameters ; girdle premedian, displaced 0.2 transdiameter ; sulcus extending
from apex to antapex; greenish vellow chromatophores. Length, 60#. Ply-
mouth Sound, England, June.

DescriptioN.—The body is somewhat asymmetrical, ellipsoidal posteriorly, conical anteriorly,
its length 1.86 transdiameters at the widest part. The transverse and dorsoventral diameters
are nearly equal. The hypocone greatly exceeds the epicone in size, its length being greater by
0.36, with a continuously wider transdiameter. The epicone has the shape of a cone of about
80°, with a broad, blunt apex and slightly concave sides. It has a length on the left and right
sides of about 0.16 and 0.19 respectively of the total length of the body. The sides of the
hypocone are subparallel, in ventral view, rounding posteriorly. In lateral view the ventral
side is nearly straight, the dorsal side convex. The antapex is broad and rounded with a deep
trough on the ventral face.

The girdle is premedian in position. Its distance from the apex on the left and right sides
is 0.16 and 0.19 respectively of the total length of the body. Its path is that of an irregularly

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 199

descending left spiral. The first part of its course makes a short, abrupt posterior turn, beyond
which it turns anteriorly until it reaches the dorsal side. It passes across this in a nearly
transverse direction, turning posteriorly on the ventral face, joining the suleus with a posterior
displacement of 0.2 transdiameter. The furrow is wide, about 0.06 transdiameter, and deeply
impressed. The suleus extends in a sinuous line from the left side of the apex to the antapex.
On the hypocone it lies at the base of a deep trough which indents the ventral face. The sides
become widely deflected near the antapex. The anterior flagellar pore evidently opens at the
proximal junction of the girdle and sulcus, the posterior pore near the distal junction.

The nucleus is a large, ellipsoidal body in the anterocentral part of the hypocone. Its major
and minor axes are 0.73 and 0.6 transdiameter respectively. The remainder of the eytoplasm
is filled with numerous, greenish yellow chromatophores.

Dimenstons.—Length, 60; transdiameter, 32”; axes of nucleus, 32” and 19.

OccuRRENCE.—This species was figured by Lebour (1917b) from a single
specimen taken in June from the waters of Plymouth Sound, England.

Compartsons.—This form is evidently one of the connecting links between
Amplhidinium and Gymnodinium, as shown in its structure. The epicone, how-
ever, has a relative length too great to include it with Amphidinium. This form
and the one deseribed by Lebour (1917b) as Gymnodinium pseudonoctiluca are
separated mainly by size and a slight variation in color. It belongs in the sub-
genus Gymnodinium.

SynonyMy.—The name, G. viridis, assigned to this species by Miss Lebour
(1917b), is preoccupied by Penard’s (1891) species, G. viride. We therefore
propose for Lebour’s species the name G. conicum.

Gymnodinium contractum sp. nov.
Plate 5, figure 52; text figure X, 2

DraGcnosis.—A small species with subovoidal body, its length 1.43 transdi-
ameters; girdle submedian, without displacement; sulcus on hypocone only;
surface on epicone furrowed; plasma green with rose red granules. Length,
63. Pacific off La Jolla, California, August.

DescrrpTion.—The body is subovoidal, with broad apices, nearly circular in cross-section,
widest anteriorly, its length 1.43 transdiameters at the widest part. The epicone exceeds the
hypocone in size, its length being greater by about 0.14 of itself, and its transdiameter somewhat
greater. The epicone is subhemispherical in outline with the apex protruding slightly beyond
the broad curve of the anterior part of the body. Its length is 0.52 of the total length of the
body. The hypocone is somewhat narrower than the epicone, sharply contracted a short distance
below the girdle to 0.77 transdiameter of the epicone. It expands slightly posteriorly, where
it is rounded with deeply notched antapex.

The girdle is submedian in position, its distance from the apex about 0.52 of the total length
of the body. The furrow is wide, about 0.08 transdiameter in width, and deeply impressed with
smooth, overhanging borders. It forms a complete circle around the body without displacement.
The suleus extends from the girdle posteriorly to the antapex. It forms a shallow channel
anteriorly and about midway of its length widens and at the same time sinks deeply into the
body, deeply excavating the ventral surface of the antapex. The anterior flagellar pore opens
at the junction of girdle and suleus, the posterior pore about two widths of the girdle posterior
to that point.

200 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The nucleus is a large ellipsoidal body in the anterior part of the organism. It is filled with
fine, moniliform chromatin strands. Its major and minor axes are about 047 and 0.36 trans-
diameter respectively. A sacklike, bilobed pusule opens into the anterior flagellar pore. The
cytoplasm is finely granular, clear and transparent. Nutrition is holozoic, as the presence of
two large food masses indicates. One of these is yellow ochre in color and the other bluish grey.
Seattered through the body are minute, dark, highly refractive granules. The color of the
plasma is a diffuse, light fluorite green with minute, rose red granules congregated at the apical
or antapical regions or both.

The surface of the hypocone is smooth, that of the epicone is marked by longitudinal furrows
outlined by green lines. These are sometimes deeply impressed, and are short, fading out at
the girdle and near the apex.

Diuenstons.—Leneth, 63-89; transdiameter, 44-58; axes of nucleus, 21

and 16z.

OccURRENCE.—This was taken August 6, 1917, with a No. 25 silk net, 4 miles
off La Jolla, California, in a haul from 60 meters to the surface and in a surface
temperature of 21°2 C. On August 8 it was found at approximately the same
place, in a haul from 80 meters to the surface and a surface temperature of
22°5 C. On August 15 five individuals were observed in a haul 0.75 of a mile
off La Jolla from 80 meters to the surface.

ComMPparisons.—This species is closely related to G. suleatum and G. rubri-
cauda in its coloring and general appearance, vet differs in its relative propor-
tions and its surface markings. It belongs in the subgenus Gymnodinium.

Gymnodinium corpusculum (Perty) Saville-Kent
Text figure BB, 14

Peridinium corpusculum Perty (1852), p. 162, pl. 7, fig. 14.
Gymnodinium corpusculum, Saville-Kent (1880-82), p. 443.
Description.—A minute form with ovoidal or ellipsoidal body, the length 1.3 transdiameters.

The girdle is near the posterior end, making the epicone much larger in size than the hypocone.
The color is ight brown or greenish yellow. Length, 132. Fresh water in Switzerland.

SynonyMy.—This was figured by Perty (1852) as Peridinium corpusculum
and the name changed to Gymnodinium corpusculum by Saville-Kent (1880-82).
Perty’s figures lack sufficient morphological characters to establish it as a good
species. Its affinities seem to be with Gymnodinium, near G. muse, but avail-
able data render it unidentifiable and it must be placed in species incertae sedis
until further investigation shall rediscover it and make its status definite.

Gymnodinium costatum sp. nov.
Plate 3, figure 33; text figure Z, 10
DiaGnosis.—A large species with subovoidal body, its length 1.66 transdi-
ameters; girdle submedian, displaced 0.22 transdiameter; sulcus extending
from apex to antapex; surface ridged; color, grevish pink. Length, 150-.
Pacific off La Jolla, California, June to August.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 201

DescrieTioN—The body is large, subovoidal, widest near the equator with rounded apices,
circular in cross-section, its greatest length 1.66 transdiameters at the widest part. The epicone
exceeds the hypocone in size, its length being greater by 0.2 of its own length. It is dome-
shaped with symmetrically rounded sides and broad, slightly ecrenulated apex. It has a length
on the left and right sides of 0.5 and 0.62 respectively of the total length of the body. The
hypocone is narrower than the epicone with its sides less rounded, tapering posteriorly to the
broad, truncate antapex. This is deeply exeavated by the suleal notch and its borders crenulated
by the surface ridges terminating in the furrow.

The girdle forms a descending left spiral with a posterior displacement of its distal end of
0.22 transdiameter and an overhang of about 0.07 transdiameter. Its proximal end joins the
sulcus at a distance from the apex of 0.50 and its distal end 0.62 of the total length of the body.
The furrow is wide, about 0.07 transdiameter and deeply impressed, the borders, especially on
the anterior side, overhanging it, thereby reducing its apparent width by one-half. In some
forms the crenate surface is in evidence along the borders of the girdle, in others the crenulations
along the borders are obscure. The sulcus begins as a slightly enlarged pit at, or somewhat to
the left of the apex, passes posteriorly to the girdle in an almost straight line and continues its
course to the antapex in a sigmoid curve. The furrow is narrow anteriorly, enlarging to twice
its width at the girdle and again behind the region of the posterior pore. Near the antapex it
deepens to about 0.7 of the transdiameter of the body at that plane, forming a deep excavation
at the antapex. The anterior flagellar pore opens at the proximal junction of the sulcus and
girdle, the posterior pore a short distance below the distal junction.

The cell contents consist of a spheroidal nucleus, a cluster of subspheriodal bodies varying
in color from light saffron yellow to dark orange yellow, small green rodlets and minute refractive
granules. The nucleus is located in the anterior part of the hypocone, just behind the girdle
and is filled with coarse, moniliform chromatin strands and a single minute, excentrically located
nucleolus. Its axis is about 0.4 transdiameter in length. Large, spheroidal food masses were
present in all individuals examined, with only slight variations in size, color, and position.
Clustered around and among them were numerous dark purplish, highly refractive bodies. These
are double-contoured and presumably fatty in nature. A greyish pink pervades the cytoplasm
as a whole, fading out as the animal becomes moribund. A small club-shaped pusule is connected
with the anterior flagellar pore by a long, slender canal.

The surface is regularly marked by stout, longitudinal, equidistant, yellowish striae. These
are about the same in number on both epicone and hypocone, about 23 across the ventral face
at the girdle, decreasing by extinction at various levels towards the apices, so that there is no
considerable approximation of the striae in these regions. They lie in the troughs of shallow
furrows, with rounded ridges between, which give a crenate appearance to the borders at the
girdle and at the apices. The small, slender, green rodlets are arranged at irregular intervals
along the ridges, at right angles to and immediately beneath the surface.

Druensions.—Leneth, 150-154; transdiameter, 90/; diameter of nucleus,
20u. .

OccuRRENCE.—This species was first seen July 16, 1906, in a surface haul
with No. 20 net, 1 mile off La Jolla, California. One individual was taken
June 25, 1917, with a No. 12 net in a haul 6 miles off La Jolla, from 80 meters
to the surface and in a surface temperature of 18°3 C. It was found again
on June 28 under approximately the same conditions. It was noted July 23
and thereafter was quite abundant, being found in most of the hauls taken up
to August 13.

202 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Comparisons.—This is one of the largest and at the same time most striking
members of the genus Gymnodinium. While it lacks the highly differentiated,
mammillated ectoplasm of G. pachydermatum, it possesses a thick periplast of
much firmer consistency than the members of the other subgenera of the genus;
it is therefore placed in the subgenus Pachydinium, near G. canus sp. nov., G.
coerulum, Dogiel, G. puniceum sp. nov., and G. wilczeki Pouchet, all with some-
what ribbed, coarsely striate surface (figs. X, 1, 4,5, 8). It is the largest of the
group, lacks the contracted apex of G. canus, differs in color from G. coeruleum,
has a proportionally larger epicone than G. puniceum, and wholly different
proportions from G@. wilezeki.

Gymnodinium cucumis Schiitt
Text figure Y, 16
Gymnodinium cucumis Schiitt (1895), pp. 100, 108, 111, 116, 117, pl. 21, fig. 64.

Dracnosts.—A large species with slender fusiform body, its length 3.24
transdiameters; girdle with a descending left spiral course displaced about 2.5
of its own width; sulcus extending from apex to antapex; surface striate.
Length, 210+, Mediterranean at Naples or the Atlantic.

Description.—The body is long, slender fusiform, slightly wider posteriorly, tapering at
both ends, its length 3.24 transdiameters at the widest part. The epicone exceeds the hypocone
by about 0.39 of its own length. It is conical (32°) in shape, slightly asymmetrical with a
narrow, blunt apex. It has a length at its left and right sides of 0.55 and 0.6 respectively of
the total length of the body. The hypocone is broader (45°) with a narrow, blunt antapex.
Its length from the proximal and distal ends of the girdle is 0.4 and 0.32 respectively. The
dorsoventral and transverse diameters are equal.

The girdle is postequatorial, meeting the suleus proximally about 0.55 and distally 0.60 of
the total length of the body from the suleus. It follows a descending left spiral course, displaced
posteriorly about 2.5 times its own width. It is a deeply imbedded furrow, 0.09 transdiameter
in width with overhanging, ribbed borders. The suleus extends from the apex to the antapex
in an irregular line but with little or no torsion. The positions of the flagellar pores are not
shown in Schiitt’s (1895) figures, though the longitudinal flagellum is shown, projecting from
the distal end of the suleus.

The nucleus is a relatively small, spheroidal body in the central part of the hypocone. Its
axis is 0.4 transdiameter in length. A large sacklike pusule extends along the transverse plane
of the body below the girdle, opening probably into one of the flagellar pores. A number of
food bodies were shown in one of Schiitt’s figures (1895, pl. 21, fig. 64). The surface is striate
with a strong tendeney towards the formation of ridges between the striae.

Divenstons.—Length, 211“; transdiameter, 654; diameter of nucleus, 26+.

OccuRRENCE.—Figured by Schiutt (1895) from the collections of the Plank-
ton Expedition, presumably from the Mediterranean at Naples or the Atlantic.
Its occurrence has not been recorded elsewhere.

Comparisons.—This is the second largest species in the genus or even in
the Gymnodinioidae thus far described, one species only exceeding it in length,
G. dogicli, with a length of 212. In the presence of ribs between the striae on

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 203

the surface it resembles G. costatum. It belongs in the subgenus Lineadinium,
in which no other species approximates it in size, proportions, or nature of the
surface, except G. costatwm, as above noted.

Gymnodinium diploconus Schiitt
Text figure Y, 6

Gymnodinium diploconus Schiitt (1895), pl. 24, fig. 78.

G. diploconus, Schiitt (1896), p. 5, fig. 5, B, C.

G. diploconus, Lemmermann (1899), p. 358; (1910), p. 618.
G. diploconus Entz, Jr. (1902), p. 92; (1905), p. 108.

DraGnosis.—A medium sized species, with biconical body with subtrunecate
apices, its length 1.24 transdiameters; girdle without displacement; sulcus ex-
tending from the girdle to the antapex; surface finely striate. Length, 57+.
Atlantic or Bay of Naples; Pacific off La Jolla, California, June, July.

DescripTion.—The body is biconical, broadly flaring in the middle region around the girdle
and tapering to the broadly subtruneate apices, its length 1.24 transdiameters at its widest part.
It is nearly circular in cross-section. The hypocone and the epicone are subequal. The epicone
is conical, about 55° in the anterior part, the posterior portion flaring at the girdle. It has a
length of about 0.39 to 0.50 of the total length of the body. The conical portion of the hypocone is
slightly narrower than the epicone (40°) with the anterior portion flaring broadly to meet the
girdle. The antapex is blunt with a small suleal notch. Our specimen (fig. Y, 6) is broader
and stouter than that of Schiitt (1895).

The girdle is premedian in position, having a distance of about 0.39 of the total length of
the body from the apex or may be median and equatorial. It follows a circular path around
the body with no posterior displacement or with a displacement of less than half its own width.
The furrow is narrow and deeply imbedded with overhanging borders. The suleus extends
from the girdle to the antapex, following a slightly sinuous course. The anterior flagellar pore
is located at the anterior junction of the girdle and suleus, the posterior pore is about midway
between the girdle and antapex.

The nucleus is a spherical body centrally located. Its diameter is about 0.24 transdiameter
of the body in length. Numerous spherules of varying size are found in the hypocone, especially
numerous at the antapex, and fewer in the epicone. Stout, rod-shaped, yellowish chromatophores
are scattered through the peripheral zone. The surface is covered with fine longitudinal striae,
about equal in number on both ends of the body, and about 30 across the ventral face.

Drmenstons.—Leneth, 57-80; transdiameter, 46-63; diameter of nucleus,
12-20».

OccuRRENCE.—This was figured by Sehiitt (1895) from the collections of
the Plankton Expedition from the Bay of Naples or from the Atlantic. It
also occurred at La Jolla, California, in collections made June 30, 1904, in a
haul 12 miles offshore, from 300 meters to the surface, and on July 5, 1904, 10
miles offshore, in a haul from 290 meters to the surface.

Comparisons.—This belongs in the subgenus Lineadinium, and stands near
G. heterostriatwm nom. sp. nov. (fig. Y, 7), but has equal numbers of striae on
both ends of the body. In the number and fineness of its striae it resembles G.
radiatum sp. nov. (fig. Z, 9) and G. multilineatum sp. nov. (fig. Y, 18).

204 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

There is some question as to the identity of Schiitt’s species and our speci-
mens. Our individuals (fig. Y, 6) were more rotund than his, and the sulcus
extends to the apex, while in his figures it is limited to the hypocone. The
surface striation is strikingly similar and for this reason we do not separate
them.

Gymnodinium dissimile sp. nov.
Plate 4, figure 35; text figure X, 32

DracNnosts.—A small species with rotund ellipsoidal body, its length 1.17
transdiameters; girdle postmedian, displaced half its own width; sulcus ex-
tending from apex to antapex; color grey green. Length, 48. Pacific off La
Jolla, California, August.

DeEscripTION.—The body is rotund, deeply constricted by the girdle, with broad apices, widest
anteriorly, its length 1.17 transdiameters at the widest part. A cross-section of the body is
nearly circular. The epicone greatly exceeds the hypocone in size, its length being greater by
0.46, its transdiameter by 0.07. The epicone is subspherical, occupying a sector about 210°
of a sphere, with broad apex. It has a length on the left and right sides of 0.62 and 0.64
respectively of the total length of the body. The hypocone is constricted anteriorly by the
girdle, rounded posteriorly with the antapex deeply notched by the distal end of the sulcus.

The girdle is situated posterior to the midplane of the body, with a distance from the apex
on the left and right sides of 0.62 and 0.64 respectively of the total length of the body. It
deeply constricts the body, the transdiameter of the girdle being about 0.8 of the greatest trans-
diameter of the body which is in the lower third of the epicone. It extends around the body
in a nearly transverse direction with a slight posterior displacement on the right of about half
its own width. The furrow is wide, about 0.07 transdiameter, and deeply impressed with
smoothly rounded sides.

The suleus begins a short distance below the girdle and extends posteriorly to the antapex.
It is a shallow trough on the epicone, becoming deeper on the hypocone until near the antapex
it reaches the dorsal border of the body, deeply notching that part of the hypocone. The anterior
flagellar pore is found at the proximal junction of the girdle and sulcus and the posterior pore
midway between that point and the antapex.

The nucleus is a relatively large, ellipsoidal body in the center of the organism. It is filled
with coarse, moniliform, chromatin strands following its long axis. Its major and minor axes
are 0.52 and 0.45 transdiameter in length respectively.

A small sacklike pusule opens into each flagellar pore. The cytoplasm is granular and grey
green in color. A few vacuoles filled with a fiuid colored like that in the pusules are found in the
anterior part of the body. In the peripheral zone are numerous blue-green oil drops and dark,
refractive granules. No striae or other surface markings were observed.

Dimenstons.—Length, 48; transdiameter, 40“; axes of nucleus, 21” and 18+.

OccURRENCE.—A single specimen was taken August 3, 1917, 6.5 miles off
La Jolla, California, with a No. 000 net, in a haul from 80 meters to the surface
and in a surface temperature of 21°2 C.

ComParisons.—In size, proportion, larger epicone, constricted girdle, and
posterior sulcal notch this species is very close to G. contractum sp. nov. (fig.
X, 2), but differs from it in having the sulcus extended upon the epicone, in the
absence of all striations, and in the absence of the reddish color.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 205

Gymnodinium dogieli sp. noy.
Plate 3, figure 34; text figures AA, 1, 8

Dracnosis.—A large species with biconical body, its length 2.03 transdiam-
eters: epicone concave; Submedian girdle, displaced nearly its own width; sulcus
extending from a short distance above the girdle to the antapex; differentiated
ectoplasm; color orange yellow. Length, 193”. Pacific off La Jolla, California,
July, August.

DescripTtion.—The body is nearly biconical, slender campanulate anteriorly, wide posteriorly,
with narrowly rounded apices, its length 2.03 transdiameters at the widest part. The epicone
exceeds the hypocone in length by about 0.3 of its length, but being much narrower is less in
volume. It forms a long, slender cone, the sides of which form an angle of about 18° with the
longitudinal axis of the body anteriorly and in the posterior third an angle of about 43°. The
sides are thus concave and symmetrical with narrowly rounded apex. Its length is about 0.56
of the total length of the body. The hypocone forms a broader cone, its sides forming an angle
of about 35° with the longitudinal axis. At the girdle they flare out into a wide, shelflike
extension to serve as its anterior border. The sides are symmetrically rounded with a broadly
rounded antapex without suleal noteh.

The girdle is protuberant, located shghtly posterior to the middle of the body, its distance
from the apex being about 0.56 of the total length of the body on the right, shghtly less on the
left side. Its distal end is displaced posteriorly somewhat less than its own width. The furrow
is wide, about 0.06 transdiameter, and is deeply impressed with widely overhanging borders,
the proximal border cut under by the furrow, the distal gradually rounded. The sulcus invades
the epicone for a very short distance only as a rather shallow furrow. Beyond the girdle it
extends as a shallow trough in an almost straight line to the antapex, expanding slightly
posteriorly, until at the antapical region its borders spread out to meet the posterior borders
of the body on each side of the antapex. The anterior flagellar pore opens at the proximal
junction of the girdle and sulcus, the posterior flagellar pore at about 0.3 of the distance from
girdle to antapex.

The nucleus is a large ellipsoidal body in the posterior part of the hypocone. Its major and
minor axes are about 0.4 and 0.27 transdiameter in length respectively.

A small, spherical pusule opens into the posterior flagellar pore through a long, slender canal.
The cytoplasm is finely granular and is usually filled with various cell inelusions. In the
central region near the anterior pore was a large group of small, highly refractive, double-
contoured, dark greenish granules. Mingled with these were a number of yellowish spheroidal
bodies, probably food masses. Above these and almost filling the epicone were large vacuoles
of a faint bluish color, presumably of a fatty nature. At the apex were a smaller group of the
same refractive spherules found in the central part of the body, with a group of radial, greenish
rodlets. A second group of rodlets was found just above the girdle region and a third group
of longer rodlets radiating out from the spherical part of the pusule. Partly fillmg the hypocone
and reaching upward into the epicone were large vacuoles filled with a pink fluid like that found
in the pusule.

The protoplasm is divided into distinct ectoplasm and endoplasm. The ectoplasm is about
4 in thickness in the hypocone and shghtly less in the epicone. It is composed of a thin, double-
contoured layer, bright yellow in color, surmounted peripherally by an alveolar layer. The
alveoli are rounded outwardly, giving to the outline of the body an uneven, wavy line. This
layer is deep orange at the antapical region, shading to a lighter tone anteriorly. The color of
the endoplasm is a greenish yellow with bluish tinges. The combination of colors in this species
gives a rich Oriental effect, impossible adequately to describe or to reproduce with water colors.

206 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Divensions.—Length, 193 to 212; transdiameter, 954 to 110“; major and
minor axes of nucleus, 42H and 26pr.

OccURRENCE.—The individual figured was taken June 27, 1917, with a No.
12 silk net, in a haul 6.1 miles off La Jolla, California, from 120 meters to the
surface and in a surface temperature of 20°6 C. It was taken on July 20, 6
miles off La Jolla, and on July 27, 4 miles off La Jolla, with a No. 25 silk net,
from 80 meters to the surface and in a surface temperature of 21° C. On
August 13 it was quite abundant in a haul 0.75 miles off La Jolla from a depth
of 88 meters and in a surface temperature of 21°9 C, 6 individuals being ob-
served in a short examination of this catch.

Comparisons.—This is one of the largest species of Gymnodinium thus far
described, the length of the longest individual observed, 212, being the greatest
length on record, the nearest approach to it being G. cucwmis with a length of
2104. It is also one of the most highly differentiated species in the genus in
its cytoplasmic structure, resembling in this respect G. pachydermatum sp. nov.,
G. amphora sp. nov., and G. abbreviatum sp. nov. (figs. AA, 5, 6; fig. Z,7). Like
them it is holozoic in nutrition, the presence of numerous green rodlets and
masses of refractive bodies indicating a high degree of metabolism. It is one
of the most striking, richly colored dinoflagellates found in the La Jolla region,
sharing that distinction with G. pachydermatum, which it greatly resembles in
color. It belongs to the subgenus Pachydiniwm, with these species, and differs
from them in its longer, more attenuate epicone and less displacement of the
girdle.

Gymnodinium doma sp. nov.
Plate 5, figure 57; text figure X, 31

Dracnosts.—This is a small species with ovoidal body, its length 1.43 trans-
diameters; girdle premedian, displaced about twice its own width; sulcus short
on both epicone and hypocone; color blue grey. Length, 59#. Pacific off La
Jolla, California, July.

Description.—The body is ovoidal with broad apices, circular in cross-section, widest anter-
iorly, its length 1.43 transdiameters at the widest part, which is at the girdle. The hypocone
exceeds the epicone in size, its length being greater by about 0.23 of its own length, though its
transdiameter is somewhat less. The epicone is hemispherical in outline with symmetrically
rounded apex. It has a length on the left and right sides of 0.33 and 0.45 respectively of the
total length of the body. The hypocone is elongate hemispherical, or campanulate in outline,
flaring at the girdle, tapering shghtly posteriorly with broad rounded antapex.

The girdle is premedian in position, its anterior junction with the suleus occurring at a
distance from the apex of 0.33 of the total length of the body. It passes around the body in a
transverse direction for 0.75 of its course, beyond which it turns posteriorly and joins the suleus
at an angle of 70° with the main axis of the body. It is displaced about twice its own width.
The furrow is wide, about 0.09 transdiameter in width, and is deeply impressed with smooth
borders. The sulcus is short, beginning midway of the distance between girdle and apex on
the epicone and extending posteriorly for about the same distance on the hypocone. Its course

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 207

is that of a sigmoid curve, forming a shallow trough which soon fades out. The anterior flagellar
pore is found at the proximal junction of the girdle and sulcus, the posterior pore a very short
distance beyond the distal junction.

The nucleus is elongated, somewhat reniform, its long axis coinciding with the short axis of
the body. It is filled with rather large, moniliform chromatin threads following its long axis.
Its major and minor axes are 0.6 and 0.36 transdiameter in length respectively.

A large, ellipsoidal pusule is situated in the posterior part of the hypocone and opens into
the anterior flagellar pore by a long narrow tube. The cytoplasm is finely granular. Seattered
through it are small vacuoles filled with fluid of the color of the pusule. Near the surface and
at right angles to it are numerous small, greenish rodlets. A large yellowish food mass was
found in the antapical region. The general color of the body is bluish grey, shading to orange
in the peripheral zone. Nutrition is holozoic, as indicated by the presence of ingested food
masses.

Dimensions.—Lenegth, 59; transdiameter, 41; axes of nucleus, 254 and 15v.

OccURRENCE.—One individual was taken on July 2, 1917, with a No. 12
silk net in a haul taken 6 miles off La Jolla, California, from 20 meters to the
surface and in a surface temperature of 21°4 C.

Comparisons.—In its peripheral zone of short radial rodlets this species
resembles some species of Gyrodinium, such as G. fissum and G. heterostriatum,
though the rodlets are fewer in number than in the case of the latter species.
They are probably concerned with the metabolism of the cell. In the anterior
location of the girdle and the consequent reduction in size of the epicone it
resembles G. fulgens, G. conicum, and G. pseudonoctiluca (fig. X, 30, 27, 35).
Tt belongs to the subgenus Gymnodinium, though its proportions are near to
those of the striate species included in Lineadinium (fig. Y), especially to G.
gracile Bergh (fig. Z, 3) and G. heterostriatum (fig. Y, 7). However, it is
wholly devoid of striae. It resembles G. ravenescens in size, displaced girdle,
and short sulcus, but has a more tapering hypocone, and lacks chromatophores.

Gymnodinium filum Lebour
Text figure X, 20
Gymnodinium filum Lebour (19176), p. 198, fig. 9.

Dracnosts.—A small, slender species with biconical body, its length 4.06
transdiameters; girdle anterior, without displacement; sulcus short on epicone,
long on hypocone, reaching to within a short distance of the antapex; colorless.
Length, 654. Plymouth Sound, England, July.

Description.—The body is long and slender, tapering to a threadlike point posteriorly,
widest anteriorly, its length 4.06 transdiameters at the widest part. The dorsoventral diameter
is slightly less than the transdiameter. The hypocone exceeds the epicone in length by about
0.74. The epicone is conical, about 60°, with narrow, blunt apex. Its length is about 0.2 of
the total length of the body. The transdiameter of the base is very slightly greater than its
height. The hypocone is long, slender conical, its angle about 20° and its length slightly more
than three times its greatest transdiameter. The antapex is drawn out into a long, slender point.

208 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The girdle is placed far anteriorly, its distance from the apex about 0.2 of the total length
of the body. It forms a complete circle around the body without displacement. The furrow
is about 0.12 transdiameter in width and deeply impressed. The suleus begins about midway
between the girdle and apex and extends posteriorly in a straight line to within a short distance
of the antapex. The flagella and flagellar pores were not figured by Lebour (1917b).

The nucleus is ellipsoidal and is found in the posterior half of the hypocone. It is filled
with loose chromatin strands. Its major and minor axes are about 0.68 and 0.37 transdiameters
in length respectively. Nutrition is holozoic, as indicated by the large, irregular food mass near
the center of the body. In Lebour’s figures the surface is marked by lines, but these are evidently
used as contour lines, since she states that the surface is without striae. The body is clear and
colorless.

Diuenstons.—Length, 65; transdiameter, 16; axes of nucleus, 11H and 6+.

OccuRRENCE.—Figured by Lebour (1917b) from water samples collected in
July at Plymouth Sound, England.

ComMParisons.—This species shows the extreme of specialization in the genus
in the attenuate form of the body. It is placed in the subgenus Gymnodinium
because it lacks striae, the scattered longitudinal lines being interpreted as
contour lines. Should striae be present, as they may be, the species should be
transferred to the subgenus Lineadinium, where it would be grouped with other
fusiform species, such as G. cucumis (fig. Y, 16). It is unique, whatever its
allocation, with no closely resembling species in Gymnodinium.

Gymnodinium flavum sp. nov.
Plate 9, figure 100; text figure X, 7

DraGcnosis.—This is a minute species with broadly ellipsoidal body, shghtly
compressed dorsoventrally, its length 1.21 transdiameters; girdle submedian,
displaced about twice its own width; sulcus extending from girdle to antapex;
strontium yellow chromatophores. Length, 31. Pacific off La Jolla, California,
July, August.

Description.—The body is broadly ellipsoidal, almost globular in shape, with broad apices,
its length 1.21 transdiameters at the widest part. It is slightly compressed dorsoventrally, its
dorsoventral diameter being 0.93 transdiameter. The hypocone slightly exceeds the epicone in
length. The epicone is hemispherical with smoothly rounded sides and broad apex. It has a
length on the left and right sides of 0.28 and 0.41 respectively of the total length of the body.
The hypocone also has a hemispherical outline with broad antapex slightly or not at all inter-
rupted by the suleal notch.

The girdle is shghtly premedian in position. Its proximal end meets the suleus at a distance
from the apex of about 0.28, and its distal end 0.41 of the total length of the body. Its path
around the body is that of a descending left spiral, with its distal end displaced posteriorly
about twice its own width. The furrow is wide, about 0.06 transdiameter, but somewhat unequal
throughout, and is deeply impressed. The furrow undereuts the anterior lip, gradually curving
out posteriorly to meet the surface of the body. The suleus rarely or never extends upon the
epicone. It extends posteriorly to or near the antapex as a slightly sinuous line. Its width
appears to be irregular. The left border projects more or less above the general surface and
frequently forms an overlap partly covering the trough. This slightly raised appearance of

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 209

the left side can be traced into the epicone where the sulcus is absent as a distinct furrow. The
anterior flagellar pore is found near the lower border of the proximal end of the girdle and
suleus. The transverse flagellum usually traverses the entire length of the girdle. The posterior
pore is slightly posterior to the distal junction of the girdle and sulcus.

The nucleus is spheroidal, and situated below the girdle on the left side of the hypocone. Its
axis is about 0.3 transdiameter.

The cytoplasm is clear and pearl grey in color. In the peripheral zones are leaflike chromato-
phores of strontium yellow color. These are quite variable in size and also in number, ranging
from 2 to 20 or more. In the deeper parts of the protoplasm are numerous blue-green bodies,
usually one large one in the posterior half of the body and much smaller ones located elsewhere.
In the peripheral zone outside the layer of chromatophores are numerous, minute yellowish
green rodlets, invisible under the low powers of the microscope. These may vary from a densely
packed layer to a few scattered ones and are probably metabolic in origin. No striae or other
surface markings were detected.

Dimenstons.—Length, 26-35; transdiameter, 21-28; diameter of nucleus,
10-.

OccURRENCE.—This species was present in very great abundance during an
outbreak of vellow water, July 27 to August 13, 1914, along the shore at La
Jolla, California. No other organisms were present in any considerable
numbers. In some surface hauls it was present almost to the exclusion of all
other organisms, and in all the hauls made near the Biological Station at that
season it was by far the most abundant form. It entirely disappeared from
the hauls shortly after the cessation of the vellow water. A single individual
was taken July 8, 1917, 4 miles off La Jolla, in a haul from 80 meters to the
surface and in a surface temperature of 19°8 C,

PHOSPHORESCENCE.—During the occurrence of the yellow water above re-
corded there was a great display of phosphorescence in the breakers along the
shore. A few Gonyaulax and Noctiluca were present in the hauls made, but in
numbers far too small to account for this display. Unfortunately no laboratory
tests were made to determine the luminescence of Gymnodinium flavum. It
was, however, the only organism present in sufficient numbers to justify the
claim made for it, i.e., that it is strongly luminscent.

CoMPARISONS.—This species most nearly resembles the related arenaciphilous
form, G. agile, from beach sands at La Jolla, but differs from it in the relative
proportions of epicone and hypocone, in a smaller compression of the body and
in the color of its chromatophores. It belongs to the subgenus Gymnodinium.

Gymnodinium fulgens nom. sp. nov.
Text figure X, 30
Gymnodinium pseudonoctiluca Lebour (19176), p. 188, fig. 3.

Dracnosis.—A large species with stout, fusiform body, its length 2.27
transdiameters; girdle without displacement; sulcus extending from girdle to
antapex; yellow chromatophores. Length, 100¢. Plymouth Sound, England,
June, July.

210 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Description.—The body is stout fusiform, conical anteriorly and rounded posteriorly, its
length 2.27 transdiameters at the widest part. The girdle is placed far anteriorly, dividing the
body into two very unequal portions. The hypocone exceeds the epicone in length by 0.57 of
its own length. The epicone is conical (80°) with a blunt apex which is deflected slightly to
the dorsal side. The hypocone is rounded at the antapex in ventral view, in lateral view is
asymmetrical, with dorsal side rounded and ventral flattened. On each side of the sulcus the
body is drawn out into a flap with the left one shghtly wider than the right.

The girdle forms a complete circle about the body at a distance from the apex of 0.29 of the
total length of the body. The furrow is narrow with a shallow trough. The sulcus begins at
the girdle and extends to the antapex. In the middle part of its course it is obscured by the
overlapping of the drawn-out borders, which become widely deflected posteriorly.

The nucleus is an irregularly ellipsoidal body near the center of the hypocone. Its major
and minor axes are about 0.57 and 0.40 transdiameters in length respectively. The body also
contained two large food masses (?) and numerous bright yellow, elliptical chromatophores,
those in the anterior half of the body being arranged in hnes.

Dirvenstons.—Length, 100; transdiameter, 44; axes of nucleus, 25 and 19+.

OccuRRENCE.—Figured by Lebour (1917b) from collections made in June
and July at Plymouth Sound, England.

SynonyMy.—Deseribed by Lebour (1917b) as G. pseudonoctiluca Pouchet,
it presents some differences which separate it from that species, the most
striking ones being in the form of the girdle and the presence of chromato-
phores. In Pouchet’s (1885a) species the girdle turns posteriorly on the ven-
tral surface, the opposite ends meeting slightly posterior to the middle of the
body. In Lebour’s form it passes around the body as a complete circle with
little posterior deflection.

CoMPaRrIsons.—Chromatophores are more frequently found in the fresh-
water species of Gymnodinium than in the marine forms. In this characteristic,
together with the relative size of epicone and the anterior position of the girdle,
it forms an intermediate species linking Gymnodinium to Amphidinium, but is
not otherwise more primitive than species previously treated here. It belongs
in the subgenus Gymnodinium.

Gymnodinium fuscum (Ehrenberg) Stein
Text figure X, 19

Peridinium fuscum Ehrenberg (1834), pp. 270-271; (1835), pp. 126-127; (1838), p. 254,
pl. 22, fig. 15, date quoted on p. 254 as 1833 (1832) by Ehrenberg.

P. fuscum, Dujardin (1841), p. 376.

P. fuscum, Riess (1842), p. 35.

P. fuscum, Perty (1852), p. 162.

Heteraulacus fuscus, Diesing (1850), p. 100; (1866), as Heteroaulax fusca, p. 95.

Peridinium fuscum, Bailey (1850), p. 46.

P. fuscum, Claparéde and Lachmann (1858-61), p. 406.

P. fuscwm, Maggi (1874), p. 118; (1880), p. 9.

P. fuscum, Stein (1878), pp. 2, 70, 72, 78, 88, 90. As Gymnodinium fuscum, (1878), pp.
95, 97; (1883), pl. 2, figs. 14-18.

P. fuscus, Eyferth (1879), p. 19.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 211

Gymnodinium fuscum, Saville-Kent (1880-82), pp. 443, 463, pl. 25, figs. 17, 18.

G. fuscum, Bergh (1881b), p. 191.

G. fuscum, Klebs (1883), pp. 348, 351, 352, pl. 2, fig. 25 (in part, his figure is evidently

a Hemidinium) ; (1884), p. 739; (1912), pp. 391, 421.

G. fuscum, Pouchet (1883), pp. 402, 445.

Peridinium fuscum, Griffith (1883), p. 587.

Gymnodinium fuscum, Biitschli (1885), pp. 925, 964, 986.

G. fuscum, Gadeau (1890), p. 30.

G. fuscum, Schilling (1891), pp. 248, 275, pl. 10, fig. 9; (1913), p. 15, fig. 10. After Stein

(1883).

G. fuscum Levander (1894), p. 48; (1900), p. 7; (1900), pp. 14, 29, 99.

G. fuscum, Zacharias (1895), p. 184; (1896), pp. 37, 38, 51; (1896), p. 78; (1898a), p. 27;
(1898b), p. 714; (1898c), pp. 95, 109; (1903), pp. 237, 244.

. fuscum, Schiitt (1895), p. 9; (1896), p. 5, fig. 5a. After Stein (1883).

. fuscum, Entz (1896), p. 22.

. fuscum, Apstein (1896), pp. 119, 120, 121, 131, 152, 153, fig. 53, tables 1-3.

. fuscum, Lemmermann (1896), p. 94; (1900), p. 115; (1902), p. 260; (1903), pp. 118,
120, 123, 149; (1910), pp. 613, figs. 10, 11, pp. 618, 620. After Stein.

. fuscum, Ludwig (1898), p. 5.

. fuscum, Mez (1898), p. 216.

. fuscum, Schroder (1898), p. 14.

. fuscum, Iwanoff (1900), p. 140.

. fuscum, Amberg (1900), p. 83.

. fuscum, Huitfeldt-Kass (1900), p. 3.

. fuscum, Lagerheim (1900), p. 22.

. fuscum, Zschokke (1900), p. 345.

. fuscwm, Schonichen and Kalberlah (1900), p. 232, pl. 2, fig. 3; (1909), p. 252, pl. 8,
fie, 3.

. fuscum, Wesenberg-Lund (1904), pp. 106, 107, 112, tables 1-9.

. fuscum, Bachmann (1907), p. 36.

r. fuscum, Karsten (1907), p. 466.

. fuscwm, Ostenfeld (1907), p. 390.

G. fuscum, Seligo (1907), p. 96, fig. 133.

G. fuscum, Doflein (1909), p. 521, fig. 462 A; (1911), p. 527, fig. 462 A.

G. fuscum, Senn (1911), p. 623.

G. fuscum, Franeé (1912), p. 28.

Peridinium fuscum, Chatton (1912), p. 86.

Gymnodinium fuscum, Lauterborn (1913), p. 868.

G. fuscum, Cunha (1913), p. 105.

RARNR

|<

RRR RRRARAAR

RRARNR

Diaanosis.—A medium sized species with ovoidal body, slightly flattened
dorsoventrally, its length 1.5 transdiameters; girdle without displacement;
sulcus extending from girdle to antapex; color yellow brown. Length, 88. In
fresh-water swamps in central Europe.

Description.—The body is stout ovoidal, widest at the middle, slightly narrower posteriorly,
its length about 1.5 transdiameters and its dorsoventral diameter 0.33 of its transdiameter. The
epicone and hypocone are subequal. The epicone has a length of about 0.45 of the total length
of the body. It is high dome-shaped with broad apex and symmetrically rounded sides. The
hypocone is usually somewhat narrower than the epicone and tapers posteriorly to the pointed
antapex.

212 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The girdle is subequatorial in position and forms a complete circle around the body without
displacement. The furrow is shallow and about 0.08 transdiameter in width with smooth borders.
The sulcus begins at the girdle and extends posteriorly to the antapex in a straight line.

The nucleus is a small, spherical body near the anterior part of the epicone. Its diameter
is about 0.2 transdiameter of the body in length. Numerous small, yellow brown chromatophores
fill the peripheral zone of the cytoplasm.

Drvenstons.—Length, 80-100; transdiameter, about 58; axis of nucleus,
12z,

OccuRRENCE.—Described and figured by Ehrenberg (1834, date of separate
publication) from fresh water in the vicinity of Berlin, May 4. Other records
of its appearance are as follows: In Lake Plon, Germany, by Apstein (1896)
in April-June, by Zacharias (1896), and by Lemmermann (1903) in March;
by Stein (1883) near Chodau, Austria, and near Budapest, Hungary, by Entz
(1896) ; by Wesenburg-Lund (1904) in all the Zealand and Jutland lakes in
Denmark, from March to October; in Stor-Pentula Lake, Finland. by Levander
(1900) in July; near Basel, Switzerland, by Schilling (1891), in Katzen Lake,
Zurich, Switzerland, by Amberg (1900), and in Brazil by Cunha (1913).

SynonyMy.—Described by Ehrenberg (1834) as Peridinium fuscum, the
name was changed by Stein (1878) to Gymnodinium fuscum. It is the type
species of the genus, being the first one named and figured by Stein.

RELATIONSHIPS.—This species belongs to the small group of fresh-water
Gymnodinium characterized by the possession of vellow or yellow ochre chro-
matophores, and falls in the subgenus Gymnodinium sensu strictu. It is nearest
related to G. mirabile in size and general proportions.

Gymnodinium fusus Schiitt
Text figure X, 5

Gymnodinium fusus Sehiitt (1895), pl. 24, fig. 79, pl. 25, fig. 81 (in part, pl. 25, fig. 81, is
Gyrodinium falcatum sp. nov.) ; (1896), p. 5, fig. 5 D.

G. fusus, Karsten (1907), p. 340.

G. fusus, Entz, Jr. (1907), p. 11; (1909), p. 246.

G. fusus, Klebs (1912), p. 390.

G. fusus, Lemmermann (1910), p. 618.

Dracnosts.—Large sized species with spindle-shaped body, its length 2.06
transdiameters; girdle slightly premedian, its ends displaced its own width;
suleus extending from near the apex to the antapex; yellow-brown chromato-
phores. Length, 122. Mediterranean or Atlantic, Arctic, Indian oceans.

DeEscripTioN.—The body is stout spindle-shaped, widest at the middle and tapering towards
both ends, its length 2.06 transdiameters at the widest part. The hypocone exceeds the epicone
in length by 0.15 of its own length. The epicone has a length on the left and right sides of about
0.39 and 0.44 respectively of the total length of the body. It is conical (45°) with sides irreg-
ularly sloping from the blunt apex to the girdle in ventral view. The hypocone is slightly
broader (50°) and is less symmetrical. In lateral view the ventral side of the epicone is concave
and of the hypocone convex, sloping abruptly to the narrow antapex.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 213

The girdle is slightly premedian in position, meeting the suleus proximally about 0.39 and
distally 0.44 of the total length of the body from the apex. It traverses a slightly spiral course
which displaces its distal end posteriorly about its own width. The furrow is deeply impressed
and about 0.05 transdiameter in width. The suleus begins a short distance below the apex and
passes posteriorly to the antapex in an irregular course but with no torsion. It widens to about
twice its own width posteriorly. No flagella or flagellar pores are noted by Schiitt (1895).

The nucleus is ellipsoidal, and is located in the dorsal part of the hypocone. A coarse,
chromatin network is figured by Schiitt (1895, pl. 24, fig. 79,). Its major and minor axes are
0.47 and 040 transdiameter respectively. A number of oil droplets and food vacuoles are
seattered through the cytoplasm, which is also filled with stout, rod-shaped, yellowish brown
chromatophores.

Diwensions.—Length, 118-122; transdiameter, 58-59; dorsoventral diam-
eter, 59e; axes of nucleus, 274 and 22.

OccURRENCE.—Figured by Schiitt (1895) from the collections of the
Plankton Expedition probably from the Mediterranean at Naples or from
the Atlantic. The only other records are those of Karsten (1907) from the
collection of the *‘ Valdivia’? Deep Sea Expedition, from the Indian Ocean, and
Meunier (1910) from the Arctic near Spitzbergen.

SynonyMy.—Schiitt (1895) includes in this species two forms which appear
to us to be generically separate. His figure 81, plate 25, with its girdle having
a displacement of more than one-fifth (0.22) the length of the body, is gener-
ically distinct from his figure 79, plate 24, with its girdle displaced 0.06 the
length of the body. The former falls within the genus Gyrodinium and to it _
we assign the new name Gyrodinium falcatum.

Compartsons.—Schiitt (1895) figures no surface striae on this species. With
its roughly fusiform body it is unique in the subgenus Gymnodinium (sensu
strictu), except for G@. filum Lebour (1917b). Should striae be found on it the
species should be transferred to the subgenus Lineadinium, composed of striate
species, some of which, such as G. cucumis and G. aureum, are fusiform.

Gymnodinium gleba Schiitt
Text figure AA, 4

Gymnodinium gleba Sechiitt (1895), pl. 25, fig. 86; (1899), p. 629.
G. gleba, Lemmermann (1899), p. 358.

Draacnosis.—A large species with ellipsoidal body, its length 1.57 transdiam-
eter; girdle displaced its own width; sulcus extending from the apex to the
antapex. Length, 126. Atlantic or Mediterranean; Pacific off La Jolla,
California.

DescripTION.—The body is stout ellipsoidal, widest at the middle, its length 1.57 transdiameter
at the widest. part at the girdle. The epicone has a length at its left and right sides of 0.5 and
0.55 respectively of the total length of the body, exceeding the length of the hypocone by about
0.1 of its own length. It is symmetrically rounded with the apex forming a slightly rounded,
blunt elevation. The hypocone is symmetrically rounded, bilobed at the antapex by the suleal
notch.

214 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The girdle is somewhat submedian in position, meeting the suleus proximally about 0.5 of
the total length of the body from the apex and distally 0.55, being displaced about its own width.
The furrow is wide, 0.06 transdiameter, and shallow. The flagellar pores and flagella were not
noted by Schiitt (1895).

The nucleus is ellipsoidal and is located near the antapex. It is filled with coarse, chromatin
granules. Its major and minor axes are about 0.4 and 0.35 transdiameter respectively in length.
The anterocentral part of the body is occupied by a large brownish mass, evidently a food body.
The remainder of the body is filled with vacuoles of varying sizes. Color greenish grey. Seat-
tered over the surface of Schiitt’s (1895) figure are small, blister-like projections. These were
not observed in our specimen and are probably indicative of approaching cytolysis. No pusules
were noted.

Dimenstons.—Lenegth, 80-1264; transdiameter, 59-80“; axes of nucleus,
17-24 by 28-.

OccuRRENCE.—This was figured by Schiitt (1895) from the collection of the
Plankton Expedition from the Bay of Naples or from the Atlantic. A single
specimen was taken 6 miles off La Jolla, California, July 1, 1906, in a haul
from 995 meters to the surface. Unfortunately no color notes were made of
this individual.

Compartsons.—Its thickened periplast, though lacking distinct ectoplasmic
differentiation, places it in the subgenus Pachydinium, near G. pachydermatum
(fig. AA, 5), but its girdle is more nearly submedian, its form less rotund, and
it wholly lacks striae. The possession of an apical point is unusual in this
subgenus.

Gymnodinium gracile Bergh
Plate 2, figure 19; text figure Z, 3

Gymnodinium gracile Bergh (1881b), pp. 251-253, pl. 16, figs. 68, 69.

G. gracile, Entz, Sr. (1882), p. 189; Entz, Jr., as Spirodinium gracile (1902), p. 124;
(1907) Sips UT G1909)) Rips 2o4e

G. gracile, Biitschli (1885), pp. 962, 964, 975, 1017, pl. 51, fig. 4.

r. gracile, Penard (1891), p. 59.

G. gracile, Schilling (1891), pp. 200, 206.

G. gracile, Lemmermann (1899), p. 358; (1902), p. 260.

G. gracile, Ostenfeld (1906), p. 6; (1913), pp. 123, 338, 344.

7. gracile, Paulsen (1907), p. 23; (1908), p. 98, fig. 133.

r. gracile, Wright (1907), p. 5, pl. 1, fig. 9.

Not Gymnodinium gracile Pouchet (1883, p. 446, pls. 20-21, fig. 39); (1885a, p. 97);
Schiitt (1887, pp. 373, 374) ; Fauré-Fremiet (1914, p. 42). These references all deal
with Pouchet’s figure and description, both of which leave his form indeterminable.

Dracnosts.—A large species with long, subovoidal or ellipsoidal body, its
length 2.1 transdiameters, epicone subconical; girdle premedian, displaced
about twice its own width; sulcus extending from near apex to antapex; surface
finely striate; color yellowish. Length, 1054. Pacific off La Jolla, California,
July, August; Baltic and Mediterranean seas, Cattegat, Atlantic.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 215

DescripTioN.—The body is subovoidal to fusiform ellipsoidal in shape, circular in cross-
section, its length 2.1 transdiameters at the widest part at the girdle. The hypocone exceeds
the epicone in length by about 0.25 of its own length. The epicone is dome-shaped or subeconical
(50°-55°), flaring slightly at the base and broadly rounded at the apex. It has a length on the
left and right sides of 0.37 and 0.44 respectively of the total length of the body. The hypocone
is subeylindrical, flaring slightly at the girdle, and broadly rounded at the antapex, which is
sometimes notched by the distal end of the suleus. In lateral view the hypocone has an almost
straight outline on the ventral side and convex on the dorsal.

The girdle is premedian, its proximal end meeting the sulcus at a distance from the apex of
0.37 and its distal end 0.44 of the total length of the body. It oceupies a narrow, deep trough
with smooth overhanging borders. Its distal end is displaced posteriorly about twice its own
width. The suleus begins near the apex or somewhat below it and extends posteriorly in an
almost straight line to the antapex. It lies in a trough which is narrow anteriorly and widens
posteriorly, forming a broad channel along the ventral face of the hypocone, the furrow itself
remaining nearly the same width throughout. The anterior flagellar pore opens at the proximal
junction of the girdle and suleus and the posterior pore midway between the distal junction
and the antapex.

The nueleus is an ellipsoidal body found in the posterior half of the hypocone. Fine, monili-
form chromatin strands follow its longitudinal axis. Its major and minor axes are 0.54 and
0.46 transdiameters respectively in length.

Small sacklike pusules are usually present, opening into one or both pores. In one individual
the pusule was large, subspherical and located near the center of the body. From it a long
narrow canal passed to the anterior pore. The cytoplasm is finely granular and generally has
many cell inclusions. In the apical region of one individual were a group of vacuoles filled with
the pink fluid associated with the pusules. Just above the large pusule which occupied the
center of the body was a group of dark, refractive granules from which extend radial, greenish
rodlets of two sizes, long slender ones and short, thicker, more numerous ones. A small orange-
colored body, presumably a food body, was found near the girdle. The ectoplasm shows the
same differentiation into a thin layer surmountd by an alveolar layer as has been described for
G. dogicl and G. amphora.

The color of the protoplasm is a pale, yellowish grey, but the color may vary considerably
with different individuals. In some specimens observed the color was a yellowish brown with
a large, orange red food mass in the epicone. In figure 19, plate 2, the color varies from bluish
green in the apical region to yellow-green in the antapical region.

Druensions.—Length, 105-130; transdiameter, 50-61"; axis of nucleus,
25-30.

OccurRRENCE.—The first specimens were taken July 16, 1907, in a surface
haul 1 mile off La Jolla, California. On July 23 of the same season it was
taken 0.75 of a mile off La Jolla in a surface haul. It was taken again on June
29,1917, with a No. 12 silk net in a haul 1 mile off La Jolla, from 40 meters to
the surface and in a surface temperature of 21°1 C. This species occurred
abundantly throughout the summer in the surface hauls from the end of the
pier and in the deeper hauls offshore. The number of individuals noted in a
short examination of each haul would vary from 1 to 8 or more. The other
and earlier records for this species are as follows: By Bergh (18810), who
first deseribed it from the Baltic Sea; by Paulsen (1907), from the Cattegat
off Denmark; by Wright (1907), from the Atlantic off Nova Scotia in July;
by Ostenfeld (1913) from the Cattegat off the coast of Denmark.

216 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

SynonyMy.—Originally described by Bergh (1881b) as Gymnodinium
gracile. It was referred, without explanation, to Spirodinium by Entz, Jr.
(1902, 1907, 1909), but the structure of the girdle, with little displacement and
no overhang, does not justify the transfer. It stands near Spirodinium, how-
ever. Bergh’s form was slightly smaller than the forms present at La Jolla,
his measurements being 90 long and 24 wide. Pouchet (1883, 1885@) describes
two forms as G. gracile Bergh which have no resemblance to each other and less
to Bergh’s figures (1881b). His earlier one (1883) shows a Gymnodinium with-
out striae and the girdle slightly posterior to the midregion of the body. His
second one (1885a) is a Gyrodinium with the girdle premedian and displaced
0.33 of the body.

The form described by Wright (1907) as G. gracile from the cold waters
off the shores of Nova Scotia may be a doubtful member of this species. Much
more work on these forms will be required before we can say, definitely, that
these frail organisms can exist, as specifically identical individuals, in the warm
waters of the Mediterranean and off the coast of the southern part of California,
and in the cold waters of the Arctic current that bathes the eastern shores of
Canadian America. His form also lacks the striate surface characteristic of
G. gracile, but this may have been omitted in the drawing.

Comparisons.—This species belongs in the subgenus Pachydinium and finds
its nearest counterpart in G. abbreviatum sp. noy. (fig. Z, 7), differing from it,
however, in its lack of a distinct alveolar layer. It is somewhat like G. awreum
sp. noy. (fig. Y, 3) in size and general proportions, but is of a duller color, more
rotund hypotheca, different cell contents, and different striations.

Gymnodinium gracile var. exiguum Pouchet
Text figure BB, 17

Gymnodinium gracile var. exiguam Pouchet (1883), p. 447, pls. 20, 21, fig. 40.
G. gracile var. exriguum, Lemmermann (1899), p. 358.
G. gracile var. exiguum, Paulsen (1908), p. 108.

DescripTioN.—An organism with a rotund body divided into two subequal parts by the
girdle, shghtly wider anteriorly. The complete course of the girdle and the suleus are not
figured or described by Pouchet (1883). The nucleus is a small, spheroidal body near the
antapex. Near the nucleus is a large, irregular body of red pigment. The color of the organism
is pale rose. Its length is 30, its transdiameter 15n. Abundant in the Atlantic off Conearneau,
France.

Pouchet’s (1883) description and figure do not afford sufficient data for
specific determination, or even generic status. The girdle on the dorsal side
might he that of Gyrodinium. Until it has been redescribed it must, therefore,
be placed among the species incertae sedis.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 217

Gymnodinium grammaticum (Pouchet) emend. Kofoid and Swezy
Text figure X, 22

Gymnodinium punctatum var. grammaticum Pouchet (1887), p. 107, pl. 10, figs. 8-9.
G. punctatum var. grammaticum, Lemmermann (1899), p. 359.
G. punctatum var. grammaticum, Schréder (1900), p. 18.

Dracnosis.—A minute species with rotund body, its length and transdiam-
eter subequal; girdle median, without displacement; sulcus on hypocone only ;
very long red pigment spot on ventral face of hypocone in sulcus; color yellow.
Length, 25». Atlantic off Concarneau, France, September; Gulf of Naples,
Julv, August.

DeEscrIptioN.—The body is irregularly rotund, somewhat asymmetrical, rounded anteriorly,
notched posteriorly, its length and widest transdiameter subequal. The epicone and hypocone
are subequal in length, but the hypocone contracts less than the epicone. The epicone is hemi-
spherical in shape, flaring slightly posteriorly. Its length is about 0.5 of the total length of the
body. The hypocone is rounded laterally with the antapex broadly notched by the distal end
of the suleus. The right side is slightly longer than the left.

The girdle is submedian in position. Its distance from the apex is about 0.5 of the total length
of the body. It forms a complete circle around the body, the ends meeting the suleus without
displacement. The proximal lip is deeply undercut by the furrow. The sulcus is not well defined
in Pouchet’s figures (1887), but evidently extends at least from the girdle to the antapex.

The interior of the body is filled with small spherules. The nucleus was not noted by
Pouchet. An elongated red pigment spot of exceptional size extends from the girdle to the
antapex in the suleal region of the ventral surface. The general color of the cytoplasm is yellow.

Dimensions.—Length, 25-26; transdiameter, 25+.

OccuRRENCE.—Figured by Pouchet (1887) from collections made in the
Atlantic near Concarneau, France, in September. The only other record of its
appearance is that of Schréder (1900) from the Gulf of Naples in July and
August.

Comparisons.—A colored pigment spot of the type found in this species is
rare among marine Gymnodinium, though rather common among fresh-water
species. It belongs in the subgenus Gymnodinium.

CHAPTER XII

GYMNODINIIDAE: GYMNODINIUM (continued), G. HAMULUS TO
G. ZACHARIASI

Gymnodinium hamulus sp. noy.

Plate 9, figure 97; text figure Y, 5

DraGnosis.—A minute species with discoidal dorsoventrally compressed
body, its length and transdiameter subequal; girdle submedian, without dis-
placement: sulcus extending from girdle to antapex; surface striate; color
green. Length, 16.54. Sand beach at La Jolla, California, July.

DescriptioN.—The body is discoidal, rotund in ventral view and dorsoventrally flattened,
its dorsoventral diameter 0.61 of its transdiameter and its length and transdiameter subequal.
In lateral view the dorsal surface is more convex than the ventral. The epicone and the hypocone
are subequal. The epicone is semicircular in shape in ventral view with the short pointed apex
sharply deflected to the left and dorsad. Its greatest length is 0.5 of the total length of the
body. The hypocone is slightly broader than the epicone, with rounded sides and antapex
broadly notched by the distal end of the suleus. In lateral view the ventral side shows a slight
sigmoid curve in its surface with the dorsal side convex.

The girdle is submedian in position, its greatest distance from the apex being 0.5 of the total
length of the body. It forms a complete circle around the body with a slight deflection poster-
iorly on the ventral face at its junction with the suleus. The furrow is wide, about 0.11 trans-
diameters, and rather deeply impressed with smooth borders. The sulcus is wider than the
girdle, expanding to nearly twice its width anteriorly at the junction with the girdle and slightly
more posteriorly, where the borders are widely deflected and extend around to the dorsal surface,
forming a deep suleal notch at the antapex. The anterior flagellar pore is found at the union
of the two ends of the girdle, the posterior pore about one width of the girdle posteriorly.

The nucleus is spherical and is located shghtly posterior to the central part of the body.
Its axis is about 0.27 transdiameter in length.

The cytoplasm is clear and contains numerous blue-green spherules. The surface is striate
with blue-green striae, which are equidistant and parallel throughout their length, and about
twenty in number across the ventral face and equal in number on epicone and hypocone. The
general color of the organism is blue green. In many individuals a small red-brown mass,
probably a food body, is found in the epicone.

DimMenstons.—Length, 16.54; transdiameter, 16; dorsoventral diameter,
about 7; axis of nucleus, 5.

OccURRENCE.—This species was found very abundantly in the beach sands
at La Jolla, California, in July, 1914. On August 13 and 15, 1917, several
individuals were observed in the hauls made 0.75 mile offshore from 83 meters
and 70 meters to the surface respectively.

Compartsons.—This is one of the smallest of the Gymnodiniidae, a single
species, the fresh-water G. varians, 11" in length, being smaller. It is typically
a sand-beach form, and shows, in the dorsoventral compression of the body, a

[218]

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 219

characteristic of Amphidinium, one of its associates in that habitat. It was
found in company with Amphidinium scissum, A. truncatum, A. corpulentum,
and A. asymmetricum. It belongs in the subgenus Lineadinium, but is wholly
unlike any other species. The apical hook is homologous with that found in
G. vestifici, but there are wide differences in the proportions of the body between
these two species. In form, proportions, and apical hook it is close to G. agile
sp. nov. (fig. Y, 9), but this species is larger, lacks striae, and has chromato-
phores.

Gymnodinium helveticum Penard
Text figure Y, 11

Gymnodinium helveticum Penard (1891), pp. 6, 21, 22, 47, 58, 59, pl. 5, figs. 10-16.

G. helveticum, Imhof (1892), p. 175.

G. helveticum, Lemmermann (1900), p. 116; (1902), p. 260; (1910), pp. 613, 618, 619,
621, figs. 17-19.

G. helveticum, Lauterborn (1910), p. 471; (1913), pp. 864, 902, 906.

G. helveticum, Schilling (1913), p. 20, fig. 20.

G. helveticum, West (1916), p. 53.

Dracnosts.—A small species with subovoidal body, its length 1.66 transdiam-
eters; girdle premedian, displaced its own width; sulcus invading both epicone
and hypocone; surface striate; color, rose. Length, 50+. Lake Geneva, Switzer-
land, Rhine River, Germany.

Description.—The body is symmetrically subovoidal, widest anteriorly at the girdle, tapering
posteriorly, its length 1.66 transdiameters at the widest part. The epicone is shorter than the
hypocone by about 0.37 of its length. It is subconical, about 70°, with rotund sides. The apex
is acuminate-truncate with three minute, pointed projections, the middle one being about twice
the height of the other two. The epicone has a length on the left and right sides of 0.36 and
0.4 respectively of the total length of the body. The hypocone is conical, about 55°, with a
slender, acuminate antapex.

The girdle is premedian in position, its proximal end joining the suleus at a distance from
the apex of 0.36 and its distal end 0.4 of the total length of the body. The furrow is wide, about
0.1 transdiameter, its proximal end about half that width and its distal end almost obscured
by the overhanging proximal border. Its depth is about 0.3 radius and its sides form an obtuse
angle with the surface of the hypocone and an acute one with the surface of the epicone. The
suleus begins just below the apex and extends posteriorly in an almost straight line to within a
short distance of the antapex. Its borders in the posterior part are drawn out into two pointed
flaps, the one on the right side much nearer the antapex than the one on the left. The longi-
tudinal flagellum arises at the junction of the girdle and suleus. The transverse flagellum was
not observed by Penard (1891).

The nucleus is an ellipsoidal body found in the middle of the body in the region of the union
of girdle and suleus. Its long axis is parallel with the long axis of the body. It is filled with
coarse, chromatin strands lying parallel with its major axis. Its major and minor axes are
about 0.53 and 0.28 transdiameter respectively in length.

The cytoplasm is clear, with numerous refractive granules in the peripheral zone. The
general color of the organism is the rose color of the peach blossom. A small spherical pusule
is found immediately behind the point of union of girdle and sulcus. The surface is covered

220 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

by fine striae, longitudinally arranged, about 15 across the ventral face, equal in number on
epicone and hypocone, with fine, colorless granules strung along them like beads on a string.
Nutrition is holozoie.

Druvensions.—Length, 50+; transdiameter, 30“; axes of nucleus, 16” and 8.5v.

OccuRRENCE.—This was figured by Penard (1891) from Lake Geneva,
Switzerland. The only other record of its occurrence is that of Lauterborn
(1910) from the Rhine River near Neuhofen, Germany.

ComPparisons.—This species greatly resembles G. aureum, a marine form
found in the Pacific at La Jolla, California, and is probably its fresh-water
representative. The latter is larger with shghtly different proportions. The
differences might easily be accounted for by the change of habitat. It belongs
to the subgenus Lineadinium, but has no other close relations therein.

Gymnodinium herbaceum Kofoid MSS.
Plate 4, figure 44; text figure Y, 17

Dracnosis.—A small species with ovoidal body, its length 1.54 transdiam-
eters; girdle displaced its own width; sulcus extends from girdle to near the
antapex; surface on hypocone striate; chromatophores green. Length, 55v.
Mediterranean at Naples, January.

Description.—The body is ovoidal, circular in cross-section, very slightly wider anteriorly
with its length 1.54 transdiameters at the widest point. The epicone is exceeded in length by
the hypocone by 0.36 of the length of the latter. Its lengths at the proximal and distal ends of
the girdle are 0.36 and 0.43 respectively of the total length of the body. The apex is rounded,
subhemispherical. The hypocone has a length on the left and right sides of the suleus of 0.58
and 0.50 respectively of the total length of the body. The antapex is broadly rounded with no
suleal notch.

The girdle is preéquatorial in position and follows a slightly spiral course in which its distal
end becomes displaced posteriorly about its own width. Its anterior and posterior junctions with
the suleus occur at 0.36 and 0.43 respectively of the total length from the anterior end. It
occupies a furrow about 0.1 transdiameter in width which is lightly impressed with prominent
lips. The sulcus extends from its anterior junction with the girdle to near the antapex in a
straight line. The anterior flagellar pore opens at the anterior junction and the posterior pore
slightly below the posterior junction of the girdle and suleus. The transverse flagellum is about
0.5 of the length of the girdle and the longitudinal one about 1.5 lengths of the body in length.

The nueleus is a small, spheroidal body lying in the posterior half of the body. Its axis is
about 0.3 transdiameter in length. Coarse, moniliform chromatin strands follow a spiral course
about its longitudinal axis. No pusules were noted. In the central part of the epicone was a
large, spheroidal, fluid-filled vacuole, pale turtle green in color. Crowded about these were
numerous smaller vacuoles, green and blue in color. In the peripheral zone were numerous
minute, highly refractive, blue-green spherules and irregularly shaped, disklike green chromato-
phores. The surface of the hypocone is striate with blue-green striae, about ten on a hemisphere.
These fade out before reaching the girdle or the antapex. None could be detected on the epicone.

Dimenstons.—Length, 55; transdiameter, 35; axis of nucleus, 11+.

OcCURRENCE.—Several individuals observed in the plankton of the Bay of
Naples, on January 23, 1908, by the senior author.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 221

CoMPARISONS.—This species comes closest in its general size and proportions
to G. ravenescens. It differs from it, however, in its striate surface and in its
chromatophores. That it is holozoic in nutrition might be inferred from the
number and size of fluid-filled vacuoles present. In this respect it recalls the
conditions figured by Stein (1883, pl. 17, figs. 14-16) for Amphidinium steini.
This species possesses chromatophores, vet is capable of ingesting smaller
organisms (G. ravenescens and G. flavescens also exhibit indications of holozoic
nutrition). It belongs to the subgenus Gymnodinium, but in the presence of
few striae on its surface it inclines towards the next subgenus, Lineadinium.
Chromatophores are relatively rare in the subgenus Gymnodinium, being
possessed by only a few small forms, mostly fresh-water in habitat.

Gymnodinium heterostriatum nom. sp. nov.
Plate 2, figure 24; plate 5, figure 56; text figure Y, 7

Gymnodinium spirale var. obtusum Dogiel (1906), pp. 38-43, pl. 2, figs. 50-56.
G. spirale var. obtuswm, Entz, Jr. (1907), p. 17; (1909), p. 254.
G. spirale var. obtusum, Klebs (1912), p. 430.

Dracnosis.—A medium sized species with symmetrical ellipsoidal body, its
length 1.5 transdiameters; girdle submedian, displaced its own width; sulcus
extending from apex to antapex; surface heterostriate; color pinkish cinnamon.
Length, 67+. Pacific off La Jolla, California, June to August; Gulf of Naples,
May to July.

Description.—The body is of robust habit, varying in shape from broadly ellipsoidal to
biconical or ovoidal with broadly rounded apices, its length about 1.5 transdiameters. It is
nearly circular in cross-section. The epicone and hypocone are subequal. The epicone is broadly
dome-shaped with broad, rounded apex. It has a length on the left and right sides of about 0.52
and 0.59 respectively of the total length of the body.. The hypocone is subconical, about 50°,
with rounded sides and blunt apex. It is usually slightly less in transdiameter than the epicone,
with narrower antapex.

The girdle is submedian, its proximal end joining the sulcus at a distance from the apex of
0.52 of the total length of the body. It forms a descending left spiral, its distal end joining the
suleus at a distance from the apex of 0.59 of the total length of the body, being displaced about
its own width accompanied by a slight overlapping. It usually exhibits a slight sigmoid curve
at its proximal end, in the lower curve of which opens the anterior flagellar pore. The furrow
is wide, about 0.08 transdiameter, and deeply impressed, its upper lip slightly raised and cut
under almost horizontally, while the lower one is more gradually curved. The borders are
marked by a double-contoured line usually blue green in color. The sulcus is very narrow and
extends in a sinuous line from the apex to the antapex. It becomes very shallow on the hypocone
and fades away near the antapex. The posterior flagellar pore is found a short distance posterior
to the distal junction of the girdle and sulcus.

The nucleus lies slightly anterior to the center and somewhat to the right side. It is nearly
circular in outline. In one individual under observation the circular nucleus changed after
about 40 minutes to a reniform shape with a distinct hollowing out, the concavity being occupied
by a granular body recalling the dumbbell-shaped centrosphere or paradesmose of Noctiluca
(Ishikawa, 1894, Calkins, 1901, and Doflein, 1911). Mitosis was not accomplished prior to
dissolution. The axis of the nucleus is about 0.43 transdiameter in length.

222 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

A small sacklike pusule is usually present, opening into the anterior flagellar pore. The
eytoplasm is granular and generally shows numerous cell inclusions. These include minute
spheroidal oil droplets in the peripheral zone, a dense layer of short blue-green rodlets perpen-
dicular to the surface, large pinkish vacuoles and food bodies. This species showed more
remarkable cannibalistic habits than any other species of the Gymnodiniidae which we examined.
Many specimens were met in which the body had been greatly enlarged, sometimes twice the
normal size, by the ingestion of other unarmored dinoflagellates. These would often continue
active until the water on the slide had partly evaporated, when the food mass would be ejeeted
from the body by a posterior vent. The host would continue swimming about with the posterior
vent in the body gradually folding and closing in until it became invisible. One encysted
individual was noted which contained a large food mass, evidently the remains of a dinoflagellate.

The surface is covered with longitudinal equidistant striae, about 18 across the ventral face
of the epicone. These are about twice as numerous on the hypocone as on the epicone. They
may be composed of unbroken lines from the apices to the girdle or may be short, broken lines
or granules linearly arranged, diminishing in number as they near the apices. Their color is
blue green. Between the striae in surface view are seen the ends of the peripheral layer of
short rodlets.

One individual when first observed was suffused at both poles (pl. 2, fig. 24) with a reddish
brown tone, fading out centrally. This color, however, soon faded out, leaving no trace and no
aggregated condensations of colored substances. In general the color is a mixture of pale
chalcedony yellow and pinkish cinnamon diffused through the cytoplasm. Many individuals
enclosed in thin-walled hyaline cysts were noted.

Diwensions.—Length, 66-85; transdiameter, 48-72; axes of nucleus, 22
and 32».

OccuRRENCE.—This was figured by Dogiel (1906) from the Bay of Naples,
May to July. The first appearance of this species in the Pacific was recorded
July 19, 1906, from a haul made with a No. 20 silk net from 585 meters to the
surface off La Jolla, California. During June, July, and August, 1917, this
was present in most of the hauls made off La Jolla, including a few of the
surface hauls at the end of the pier at the Biological Station. The number of
individuals noted in a short examination of a single haul varied from 1 to 10.
It was the most abundant species of the Gymnodinioidae in plankton examined
by us.

Comparisons.—The food habits of this minute form make it one of the most
interesting species in the genus. In the many individuals seen practically none
was without ingested food masses. It is more sensitive to the adverse conditions
found under the microscope than most of the other species, in that the food
masses were usually disgorged shortly after being placed under observation.
This may have been caused by contact with the cover glass or by the intense
illumination required for the microscope. In its abundance of peripheral rod-
lets it resembles Gyrodinium fissum and, less strikingly, Gymnodinium doma.
It belongs to the subgenus Lineadiniwm and appears to be unique in the well
defined and seemingly general contrast in the number of striae on the epicone
and hypocone. A slight excess on the hypocone appears also in G. rubrum (fig.
Y, 4) and in G. multistriatum (fig. Y, 1).

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 223

SynonymMy.—Dogiel (1906) described, as Gymnodinium spirale var. obtusum
Schutt, a form identical with our species. Schiitt’s organism (1895) of that
name, however, is a Gyrodinium, and not the same as Dogiel’s form. We there-
fore place the latter with our species as Gymnodinium heterostriatum nom.
sp. nov.

Gymnodinium incisum sp. nov.
Plate 3, figure 27; text figure X, 33

D1acnosts.—A small species with rotund body, its length and transdiameter
equal; girdle a submedian, descending left spiral, displaced 0.19 transdiameter ;
sulcus extending from near apex to antapex; color, oil yellow. Length, 52v.
Pacific off La Jolla, California, August.

Description —The body is rotund, rounded anteriorly, deeply notched posteriorly, its length
equal to its widest transdiameter. The epicone and hypocone are subequal, their greatest lengths
being the same. The epicone is hemispherical in outline with a slight irregularity in its contour
at the apex, tending towards the formation of a low point or peak. The sides are smoothly
rounded. In cross-section the shape is nearly cireular with only a slight flattening on the mid-
ventral surface. It has a length on the left and right sides of 0.34 and 0.55 respectively of the
total length of the body. The hypocone has more steeply sloping sides than the epicone and its
greatest transdiameter is slightly less. The antapex is narrower than the apex, its sides smoothly
rounded with a deep central excavation formed by the distal end of the suleus. This produces
two lobes in ventral view, each having a length of about 0.09 of the total length of the body.
Anteriorly the sides of the hypocone flare out in a broad shelflike border to the girdle.

The girdle is slightly premedian in position for the greater part of its length. Its proximal
end joins the suleus at a distance from the apex of 0.34 and its distal end at 0.55 of the total
length of the body. Its course is that of a descending left spiral with the distal end displaced
posteriorly 0.19 transdiameter. The furrow is wide, about 0.05 transdiameter, and is deeply
impressed. Its borders are raised slightly above the surrounding surface of the body.

The suleus invades the epicone as a shallow trough which is deflected to the right at an angle
of about 42° with the median longitudinal plane of the body. It fades out when slightly more
than midway of the distance from girdle to apex. After meeting the proximal end of the girdle
it turns and passes in a nearly straight line to the antapex. The trough widens at the anterior
pore and deepens posteriorly until, in the antapical region, its depth becomes equal to the dorso-
ventral diameter at that plane. It cuts the dorsal surface of the body, forming two lateral lobes
separated by a deep excavation at the antapex. The anterior pore opens at the proximal junction
of the girdle and suleus, the posterior pore about midway between the distal junction and the
antapex.

The nucleus is a large body, ellipsoidal with slightly coneave sides. It is found in the left
anterior part of the body with its long axis diagonal to the long axis of the body. It is filled
with coarse chromatin strands. Its major and minor axes are about 0.57 and 0.34 transdiameter
respectively in length.

A small sacklike pusule opens into each flagellar pore. The eytoplasm is finely granular and
contains an abundance of minute green oil droplets scattered through the peripheral zone.
Nutrition is holozoic, as indicated by the presence in the body of an ingested Pouchetia, probably
P. rubescens. This had been partly digested, its Indian-red color still noticeable and its ocellus
conspicuous. The general color of the organism is oil yellow with a pearl grey background, the
general effect quite rich.

224 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Dioenstons.—Length, 52; transdiameter, 52; axes of nucleus, 30 and 18.

OccuRRENCE.—One individual was taken August 21, 1917, with a No. 25 silk
net, 5 miles off La Jolla, California, in a haul from 85 meters to the surface.

CoMPARISONS.—In size, shape, proportions, and suleal notch this species is
very similar to G. sulcatum sp. noy. (fig. X, 1), but differs from it in the entire
absence of the rose red color and of the scattered striae on the hypocone. Its
suleus is oblique and its girdle is rather widely displaced, while that of G.
sulcatum is without displacement.

Gymnodinium inerme (Schmarda) Saville-Kent
Text figure BB, 15

Peridinium inerme Schmarde (1854), p. 10, pl. 1, fig. 8.
Gymnodinium inerme, Saville-Kent (1880-82), p. 444, pl. 25, fig. 54.

Description.—A minute species with ellipsoidal body, its length 1.14 transdiameters. The
epicone and hypocone are equal in size with the girdle occupying the midplane of the body.
No suleal notch. The color is red. Length, 164. Egypt, March, in fresh water.

SynonyMy.—This minute form was figured by Schmarda (1854) as Peridi-
nium inerme and the name changed by Saville-Kent (1880-82) to Gymnodinium
inerme. Schmarda’s figures lack nucleus, sulcus and the location of the girdle
on the ventral face of the organism, i.e., it lacks sufficient morphological char-
acteristics to establish it as a valid species. It is, therefore, placed among the
species incertae sedis.

Gymnodinium lachmanni Saville-Kent
Text figures BB, 4, 6

Peridinium sp. Claparéde and Lachmann (1858-61), pp. 71, 73, pl. 18, figs. 21, 22.

Gymnodinium lachmanni, Saville-Kent (1880-82), p. 444, pl. 25, figs. 58, 59.

Saville-Kent (1880-82) has given this name to two forms figured as two
different, unnamed species of Peridinium from the coast of Norway by
Claparéde and Lachmann (1858-61). The two organisms differ greatly from
each other, with no indications of near relationship. They, likewise, may be,
in part (our fig. B, 4), Pertdinium which have escaped from the shells, as some-
times happens, or they may be Gymnodinium. Until they have been redis-
covered, however, they must be placed among the species incertae sedis. The
one (our fig. BB, 4) appears to be a rounding-up individual of a species near
G. marinum Saville-Kent, approaching cytolysis, and the other might be an
obliquely lateral view of a small individual of our own species, G. dogieli (fig.
Z, 1, 2), assuming that Claparéde and Lachmann have given correct magnifi-
cations of their figure.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 225

Gymnodinium lineatum sp. noy.
Plate 1, figure 2; text figure Y, 14

DraGcnosis.—Large species with ovoidal body, its length 1.7 transdiameters ;
girdle submedian in position, displaced 0.2 transdiameter; sulcus extending
from the apex to the antapex; surface striate; color, pale green yellow. Length,
1434. Pacific off La Jolla, California, July.

Descrietion.—This is one of the largest species of Gymnodinium. The body is ovoidal,
rounded at both apices, widest anteriorly, its length 1.7 transdiameters at the widest part. A
cross-section of the body is nearly circular. The epicone, having a greater width than the
hypocone, is slightly larger, though it is exceeded in length by the hypocone by 0.1 of its length.
The epicone is irregularly, somewhat asymmetrically rounded with broad apex. It has a length
on the left and right sides of 0.38 and 0.49 respectively of the total length of the body. The
hypocone is much narrower than the epicone, conical in shape, about 50°, the angle increasing
slightly near the girdle, with a broad, blunt antapex. Anteriorly it flares out in a wide, shelflike
border to the girdle.

The girdle is submedian in position. Its proximal end joins the sulcus at a distance from
the apex of 0.38 of the total length of the body. It follows a descending left spiral course
around the body and its distal end meets the sulcus at a distance from the apex of 0.49 of the
total length of the body, giving it a displacement of 0.2 transdiameter, or about 3 times its own
width. The furrow is wide, about 0.05 transdiameter, and deeply impressed with wide, over-
hanging shelflike borders. The suleus begins at the apex and extends posteriorly as a shallow
channel. It follows a slightly sinuous course which is deflected to the left posterior to the
proximal junction with the girdle, terminating near the left side of the antapex. The anterior
flagellar pore is found at the proximal junction of the girdle and sulcus. The posterior pore
is about a width of the girdle below the distal junction.

The cell inclusions consist of nucleus, pusule, vacuoles, small spherules and rose-red coloring
material. The nucleus is a large ellipsoidal body in the left central part of the epicone. It is
filled with fine; moniliform chromatin strands arranged along its shorter axis. Its major and
minor axes are about 0.47 and 0.3 transdiameter respectively in length.

A large pusule opens into the anterior flagellar pore. It has an irregular sacklike extension
anteriorly and a larger one posteriorly, both branches joining immediately dorsad of the anterior
pore. No pusule could be detected in the region of the posterior pore. The cytoplasm is coarsely
granular and alveolate in structure. Near the central part of the body is a mass of large,
greyish vacuoles and scattered sparsely through the remainder of the body are smaller vacuoles
filled with the same salmon-pink fluid found in the pusules. The general color of the organism
is a pale green yellow diffused through the body. :

The surface is marked by equidistant striae, about 25 across the ventral face. These consist
of linear series of minute, rod-shaped, blue-green, lenticular bodies. The number is approxi-
mately the same on both epicone and hypocone. On the epicone these extend from girdle to
apex, diminishing in number as they near the apex. On the hypocone they are deflected postero-
sinistrally, following the border of the sulcus on the left side but having a greater obliquity on
the right, where they extend from the girdle to the right border of the suleus.

Drvensions.—Lenegth, 112-148; transdiameter, 68"; axes of nucleus, 34
and 23+.

OccuRRENCE.—The first specimen observed was taken July 14, 1906, with a
No. 20 net in a surface haul 2 miles off La Jolla, California. The individual
figured was taken July 26, 1917, with a No. 25 net, 2.5 miles off La Jolla, ina

226 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

haul from 80 meters to the surface and in a surface temperature of 22°2 C.
The same species was noted July 27, 4 miles off La Jolla, in a surface haul with
a surface temperature of 21°9 C.

Comparisons.—This form is unique among the Gymnodiniidae in having its
surface striae extending in an oblique rather than a longitudinal direction.
This is apparently not the result of any torsion of the body. In forms having
a greater torsion of the body, as Gyrodinium and Cochlodinium, the course of
the surface striae, where such are present, is invariably longitudinal, with
only a slight tendency to follow the course of the sulcus on the left side. In
Gymnodinium lineatum this tendency is greatly exaggerated until the striae
on the right side of the body are cut off in their course by the sulcus. It belongs
to the subgenus Lineadinium, close to G. rubrum, which it approaches in pro-
portions and size as well as in color. Its surface markings are quite different
and its nucleus lacks the clear zone of that in G. rubrum.

Gymnodinium lineopunicum sp. noy.
Plate 6, figure 65; text figure X, 17

DraGcnosis.—A medium sized species with broad, ovoidal body, its length 1.09
transdiameters; girdle forming a complete circle about the middle of the body ;
suleus short on epicone and hypocone; color, pomegranate purple. Length, 78.
Pacifie off La Jolla, California, August.

DescripTion.—The body is rotund, ovoidal, broad anteriorly, tapering posteriorly, circular
in cross-section, its length 1.09 transdiameters at the widest part. The epicone is larger in
extent than the hypocone. It is hemispherical with broad apex and symmetrically rounded sides.
Its length is about 0.47 of the total length of the body. The hypocone has the shape of a cone
of about 75°, with a broad base and a blunt antapex. Its sides are symmetrical and very slightly
convex.

The girdle forms a complete circle about the middle of the body. Its distance from the apex
is 0.47 of the total length of the body. The furrow is wide, about 0.04 transdiameter, and rather
deeply impressed. The anterior border is undercut somewhat, the furrow gradually rounding
out to the posterior border. The sulcus is a very short, deep trough at its junction with the
girdle, soon fading out both anteriorly and posteriorly, its length on the hypocone being about
twice that on the epicone. The anterior flagellar pore opens at the junction of girdle and sulcus.
The posterior pore is about two widths of the girdle below the anterior one.

The nucleus is a small, broadly ellipsoidal body, placed slightly posterior to the central part
of the hypocone. It is filled with coarse, moniliform, chromatin strands. Its major and minor
axes are 0.3 and 0.21 transdiameter in length respectively.

A small sacklike pusule opens into each flagellar pore, the anterior one exceeding the posterior
one in size. The eytoplasm is finely granular, clear and translucent. The individual under
observation had ingested a Pouchetia, probably P. rubrum, which was in proeess of digestion.
A trace of the girdle remained, with the nucleus and ocellus still intact. The rose color was
still present but diffusing out through the surrounding cytoplasm of the devourer. Nutrition
in this species is patently holozoie.

The most striking feature of this organism is its color, which makes it a conspicuous object
when placed under the microscope. The background of translucent cytoplasm is a pale turtle

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 227

green. Standing out in relief against this is the pomegranate-purple coloring matter or pig-
ment, located in the peripheral zone, immediately beneath the thin periplast. This is amoeboid
in character and changes its shape and position so rapidly that it is impossible to obtain a
complete camera drawing of its appearance at one time. On the epicone it is located in stout
rods linearly arranged, on the hypocone in irregular masses held in a coarse network of the
same material. The dorsal location of this color was only a temporary localization. When
first observed it was spread over a greater portion of the body. The surface was free from
striations or other markings, but the pigment localization on the epicone strongly suggests a
fundamental tendeney in the direction of the linear organization of subpellicular substance in
parallel equidistant lines.

Dimensions.—Length, 78; transdiameter, 70“; axes of nucleus, 21” and 15r.

OccURRENCE.—This species was represented by a single individual in the
material under observation. It was taken August 8, 1917, with a No. 25 net
in a haul 4 miles off La Jolla, California, from 80 meters to the surface and in
a surface temperature of 22°5 C.

Comparisons.—This is one of the most strikingly colored species of Gymno-
dinium. It is unique, also, in the extreme mobility of the ‘‘chromatophores,”’
if one may so term the color masses. This mobility resembles the condition
exhibited by the color masses in Gyrodinium ochraccum (pl. 7, figs. 76, 82), and,
perhaps, in Erythropsis scarlatina. In the latter species, however, active move-
ment of the pigment mass was not observed, but its appearance suggested the
probability that it takes place. The striate arrangement of the color on the
epicone and the total lack of such arrangement on the hypocone suggests a
fundamental tendency towards striate organization in the cytoplasm of that
region similar to that in G. contractum.

This species is unique in Gymnodinium in the proportions of epicone and
hypocone, resulting in a balloon-shaped body, further marked off by its promi-
nent purple color pattern. It is one of the most highly specialized and widely
divergent types found in the subgenus Gymnodinium. The possibility that its
hypocone may be modified in form by the recent discharge of a large food body,
and that the color has been, in part at least, derived from, or modified by, the
food previously digested is not precluded.

Gymnodinium lira sp. nov.
Plate 3, figure 30; text figure Z, 11

Diacnosis.—This is a large species with rotund, ellipsoidal body, its length
1.47 transdiameters; girdle premedian, displaced about twice its own width;
sulcus, extending from apex to antapex; surface ribbed; color, grey green.
Length, 1034. Pacific off La Jolla, California, June, September.

Description.—The body has a rotund habit, widest in the middle with broad, rounded apices,
a cross-section nearly circular in outline, its length 1.47 transdiameters at the widest part. The
hypocone exceeds the epicone in size, being longer by 0.26 of its own length. The epicone is
dome-shaped, or convex conical, flaring slightly at the girdle, with broad rounded apex. The

228 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

right side is somewhat more convex than the left. It has a length on the left and right sides of
0.36 and 0.43 respectively of the total length of the body. The hypocone is constricted shghtly
a short distance beyond the girdle, expands in the posterior third and is rounded posteriorly,
with broad, hemispherical antapex. In the region of the girdle it flares out to form a broad lip.

The girdle is premedian, its proximal junction with the suleus occurring at a distance from
the apex of 0.36 of the total length of the body. It turns posteriorly, at an angle of 25° with
the transverse plane of the body, for a short distance, then passes almost transversely around
the body with a slight anterior deflection. Its distal end makes a short, abrupt posterior turn,
meeting the suleus at an angle of 40° from the transverse plane of the body. The furrow is
wide, about 0.05 transdiameter, and deeply impressed, its anterior lip undereut and its posterior
one gradually rounded. Both borders are raised considerably above the surrounding surface
of the body. The suleus extends from the apex to the antapex in a slightly sinuous line. The
trough is shallow and narrow with a slight widening at the junctions with the girdle, and fading
out near both apices. The anterior flagellar pore opens at the proximal junction of girdle and
suleus, the posterior pore at the distal junction.

The nucleus is ellipsoidal and is found in the anterior part of the body. It is filled with
coarse chromatin strands. Its major and minor axes are about 0.32 and 0.27 transdiameter in
length respectively.

The protoplasm is finely granular, grey green in color, and contains many large, pinkish
vacuoles. Distinet alveoli are sometimes found in the peripheral zone (fig. Z, 11). The centro-
posterior part of the body is filled with a large, irregular body, pale pink in color, containing
a smaller yellow-green body near its center. This indicates a holozoic type of nutrition. Pusules
were not in evidence in the individual studied.

A distinct pelliele is present of slightly greater consistency than most of these organisms
possess. This is shown in the fact that it is occasionally found in preserved material with body
intact, the only recognizable Gymnodinium we have met in our examination of several hundred
plankton catches made at La Jolla and preserved in formalin. The surface is covered with longi-
tudinal, equidistant ribs, yellow green in color, which are raised slightly above the surface near
the middle of the body, gradually sinking and continuing as surface lines to the apices. It may
also present high ridges on the surface. The girdle is outlined with lines of the same yellow-
green color.

Druvenstons.—Length, 103; transdiameter, 70; axes of nucleus, 234 and 19+.

OcCCURRENCE.—One individual was taken June 12, 1917, from a surface haul
at the end of the pier at the Biological Station at La Jolla, California. It was
also found in material preserved in formalin that had been collected September
24, 1904, 10 miles off La Jolla, in a surface haul with a No. 20 silk net.

Comparisons.—Although showing no differentiated ectoplasm of quite the
same type as G. dogieli and G. pachydermatum (figs. AA, 1, 5), yet its thickened
periplast places it in the same group with them. In the presence of distinct
ribs on the surface, as distinguished from striae or furrows, it stands almost
alone in Gymnodinium, G. sulcatum alone showing a few ridges on the hypocone.
Amphidinium fastigium exhibits the same type of surface markings, though the
ridges are fewer in number.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 229

Gymnodinium lohmanni Paulsen
Text figures BB, 1, 5, 12

Gymnodinium roseum Lohmann (1908), pp. 202, 252, 263-264, 366, 368, pl. 17, figs. 24-28 ;
(1911), p. 20.

G. lohmanni Paulsen (1908), pp. 99-100, fig. 137 A—D.

G. lohmanni, Ostenfeld (1913), p. 338.

Not G. rosewm Dogiel (1906), pp. 21-26, pl. 2, figs. 26-37, now Ch ytriodinium roseum
(Dogiel) Chatton (1912).

Tn 1908 Lohmann published a description and four figures of a species which
he called Gymnodinium roscum. It isa large species 70-115# long, with rotund
ovoidal body, asymmetrical, non-terminal horn, premidian transverse girdle,
rounded antapex. The sulcus was not found. In his figure 26 it appears that
the girdle is oblique, as in Gyrodinium, but this is based on preserved material,
and may be distorted or even another species, perhaps of Gyrodinium. Its
apex, however, is of the G. lohmanni type. It is probable that the asymmetrical
spiral horn is related to our apical loop of the sulcus.

The cytoplasm is filled with stout, rodlike, peripheral rhabdosomes in radial
or longitudinal arrangement and crowded with large vacuoles filled with a rosy
fluid. An ellipsoidal nucleus, with spirally arranged parallel chromatin threads,
is variously located within the cytoplasm, which also contains what appear to
be food balls of various sizes. It is evidently a holozoic species.

While its girdle is indicated, its sulcus is not delineated, hence it is impos-
sible to define its relationships with certainty, even as to its generic allocation.
We therefore leave it tentatively in Gymnodinium.

SynonyMy.—Lohmann (1908) described it as Gymnodinium roseum, using
a name preoccupied by G. rosewm of Dogiel (1906), a species which was later
transferred by Chatton (1912) to his parasitic genus Chytriodinium. Paulsen
(1908), in his monograph of the Peridiniales in ‘‘Nordisches Plankton,”’
recognized the error of Lohmann and gave the species the name G. lohmanni.

Gymnodinium lunula Schiitt
Plate 5, figure 55; text figure I

‘“‘Kystes des Péridiniens’’? Claparéde and Lachmann (1858-61), pp. 69-73, pl. 13, figs.
16-22.

Gymnodinium lunula Schiitt (1895), in part, pp. 4, 11, 43, pl. 24, figs. 80,,, 5, 19, -14, Pl. 25,
figs. 80.5, 4) -¢) -7) -11. a3; a8 Pyrocystis lunula (1896), pp. 3, 4, figs. 2 B-F.

Pyrocystis lunula, Jérgensen (1899), p. 26, tables 18, 44; (1910), p. 147.

P. lunula, Lemmermann (1899), p. 358; (1901), p. 358; (1902), p. 260; (1905a), p. 20.

P. lunula, Murray and Whiting (1899), pp. 337, 339, 340, tables 5-9.

P. lunula, Ostenfeld (1899), tables 3, 5, 6; (1900), tables 5, 7; (1906), p. 6; (1909), p. 7;
(1913), pp. 339, 344, 476.

P. lunula, Sehréder (1900), p. 13; (1906), pp. 321, 327, 3380, 339; (1911), pp. 620, 626,
651.

230 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

P. lunula, Ostenfeld and Schmidt (1901), p. 177.

. lunula, Schmidt (1901), p. 138.

P. lunula, Blackmann (1902), pp. 183, 187, fig. 8.

P. lunula, Entz, Jr. (1902), p. 92; (1905), p. 108; as Gymnodinium lunula (1907), p. 22;
(1909), p. 261.

P. lunula, Lohmann (1902), p. 52; (1908), pp. 168, 325, 326.

P. lunula, Ostenfeld and Paulsen (1904), p. 170.

P. lunula, Karsten (1905), p. 33; (1906), pp. 188, 201; (1907), pp. 233-532, tabulated
references.

P. lunula, Pavillard (1905), pp. 46, 101.

P. lunula, Apstein (1906), pp. 263-269; (1909), pp. 1-27.

Gymnodinium lunula, Dogiel (1906), pp. 1, 2, 4-20, pl. 1, figs. 1-25 (figure 20 is not of
the same species as shown in figures 22-25).

Pyrocystis lunula, Zacharias (1906), p. 509.

P. lunula, Chatton (1907), p. 284.

P. lunula, Gough (1907), pp. 190, 192.

P. lunula, Okamura (1907), p. 135, pl. 5, fig. 832; (1912), p. 5.

P. lunula, Wright (1907), p. 4, pl. 1, figs. 3-5.

P. lunula, Paulsen (1908), pp. 110, 111, figs. 153-154.

Gymnodinium lunula, Caullery (1910), p. 211.

Pyrocystis lunula, Jollos (1910), p. 208.

P. lunula, Wille (1910), p. 296.

P. lunula, Doflein (1911), p. 524, figs. 467, 468.

P. lunula, Mielcke (1911), pp. 328, 338.

Diplodinium lunula, Klebs (1912), pp. 389, 390, 442, 443, fig. 4.

Gymnodinium lunula, Kofoid and Ridgen (1912), p. 336.

Pyrocystis lunula, Schiller (1912), p. 28.

P. lunula, Cavers (1913), pp. 182, 184, figs. 9.724.

P. lunula, Poche (1913), pp. 161, 162.

Gymnodinium lunula, Pascher (1916), p. 132.

Dissodinium lunula, Pascher (1916), p. 131, fig. 3a.

Pyrocystis lunula, West (1916), pp. 55, 57, fig. 40.

P. lunula, Lebour (19176), p. 198.

ky

DiaGnosis.—A small species with ellipsoidal body, its length 1.22 transdi-
ameters: girdle submedian, displaced twice its own width; sulcus extending from
apex to antapex; color greenish yellow. Crescentic and spherical Pyrocystis
stages prevalent. Length, 22H. Cosmopolitan in neritic marine habitat.

DescripTion.—The body is broadly ellipsoidal, circular in cross-section, tapering slightly or
rounded at the apices, its length 1.22 transdiameters at the widest part. The epicone and
hypocone are subequal in size. The epicone is rounded conical in outline with convex sides and
rather broad apex. It has a length on the left and right sides of about 0.45 and 0.5 respectively
of the total length of the body. The hypocone is usually slightly more hemispherical than the
epicone, with broader antapex.

The girdle is submedian in position, its proximal and distal ends having a distance from the
apex of 0.45 and 0.5 respectively of the total length of the body. The furrow has a width of
about 0.14 transdiameter and is deeply impressed with overhanging borders. The sulcus extends
in a nearly straight line from the apex to the antapex as a wide, deep furrow. The anterior
flagellar pore opens at the proximal junction of girdle and sulcus, the posterior pore a slight
distance posterior to the distal one.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 231

The nucleus is a large ellipsoidal body near the center of the organism. Its major and
minor axes are about 0.5 and 0.3 transdiameter in length respectively.

The cytoplasm is clear and finely granular. No pusules have been observed. The color is
greenish yellow. These small forms have not been positively identified after leaving the cyst,
hence nothing can be said in regard to their nutrition and activities. Very many small indi-
viduals of this genus have been observed in the material under examination, but the rapidity
of their movements has prevented a critical examination.

Lire Cycte.—Gymnodinium lunula is one of the very few members of this
group of which we have any definite knowledge of more than one stage of its
life cycle.

Schiitt (1895-96) figured the crescent-shaped encysted forms and suggested
their connection with Pyrocystis noctiluca Murray (1885), but it was not until
the publication of Dogiel’s (1906) studies on this species that the connection
between these and the large globular forms, similar to or identical with P.
noctiluca, was established.

Owing to a complete lack of knowledge of the development of the dinofla-
gellates, the discovery of these stages was given a greater importance than
facts later revealed warranted. As a result these species were isolated from
Gymnodinium and placed in a separate family of algae, Pyrocystiae, by Black-
man (1902). It has been pointed out elsewhere in this paper that indications
lead to the conclusion that these stages are normal ones in the life cycle of many
forms, including Gonyaular, Gymnodinium, and Gyrodinium, and that the
spheroidal or variously shaped, non-motile cysts probably are a part of the
developmental cycle of most of the dinoflagellates. Dogiel (1906) pointed out
the desirability of further investigation before separating Gymnodinium lunula
from the rest of the genus, and his conclusions are confirmed by later work.

The life cycle, or the part thus far brought to light, may be divided into
three parts, the relative lengths of which are unknown. One of these is the
huge globular cyst, largely filled with vacuoles with the nucleus and most of
the cytoplasm localized at one side close to the periphery, from which proto-
plasmic strands extend out to the enclosing wall (fig. I, 1). This cell divides
into eight or sixteen moieties within the primary cyst and each of these parts
in turn becomes enclosed in slender crescentic secondary cysts (fig. I, 3, 4).
This process produces the second part or stage shown in plate 3, figure 55. The
contents of these eysts may divide into two or as many as eight moieties, each
of which develops a girdle, a sulcus, and the two flagella (fig. I, 7) and breaks
out of the cyst as a typical Gymnodinium. During the third part of this cycle
the individual may divide, either in the motile condition or on encystment
(fig. I, 9-11). This may be repeated many times apparently before any further
change takes place. What occurs between this stage and the production of the
Jarge spherical primary cyst is as yet unknown.

Dimensions.—Leneth, 22; transdiameter, 17/; axes of nucleus, Te to 10
and 5 to Te; length of crescent-shaped cyst, 104“; diameter of large globular
eyst, 155p.

232 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

OccuRRENCE.—The exact occurrence and distribution of this species is hard
to define, since it has been confused in literature with several other similar
forms, as may be seen in an examination of Schiitt’s figures (1895, 1896), as
well as those of Dogiel (1906). It is apparently cosmopolitan in the marine
habitat, having been recorded as Pyrocystis from nearly every sea where dino-
flagellates have been studied. It is abundant at La Jolla in the surface plankton
during most of the summer.

SynonyMy.—Claparéde and Lachmann (1858-61) early described these
eysts from Bergen, Norway, as developmental stages of Peridinium. First
figured by Schiitt (1895) as Gymnodinium lunula, he later (1896) changed the
name of this species to Pyrocystis lunula. Dogiel (1906) recommended its
inclusion in the genus Gymnodinium as G. lunula. Klebs (1912) further added
to the confusion already existing by creating for it a new genus, Diplodinium,
disregarding the fact that that name was already preoccupied by a ciliate in
the group Protista, Diplodinium Schuberg. Following the usage of Schutt
and the suggestion of Dogiel, we regard this species as a valid one in the genus
Gymnodinium, and base its allocation on the affinities revealed by the motile
biflagellate stage, as elsewhere in the Gymnodinioidae. It appears better to
await a fuller knowledge of life histories of Gymnodinium before accepting
Pascher’s (1916) allocation of this species in a separate genus as he has done
in erecting Dissodinium for it.

Tts affinities within the genus are obscured by our lack of knowledge of the
smaller representatives of this genus. It is close to the species G. scopulosum
in its subconical form, but is much smaller (22) than that species (47), and
lacks its overhanging epitheca.

Closer inspection of the spheroidal and cresentic cysts referable to this
species is needed to determine whether or not they may include phases of several
species.

Gymnodinium marinum Saville-Kent
Text figure X, 13

Gymnodinium marinum Saville-Kent (1880-82), p. 444, pl. 25, figs. 60-61.
G. marinum, Biitsehli (1885), p. 1017.
G. marinum, Entz, Jr. (1902), p. 125; (1907), p- 17; (1909), p. 253.

Dracnosts.—A minute species with broadly ovoidal body, dorsoventrally
compressed, its length 1.03 transdiameters; girdle premedian, without displace-
ment; sulcus extending from girdle to antapex; colorless, holozoic. Length, 30.
Infusion of hay and sea water from St. Heliers, Jersey, March.

Description.—The body is broadly oval in ventral view with broad apices, widest posteriorly,
its length 1.03 transdiameters at the widest part. It is compressed dorsoventrally to about
0.62 of the widest transdiameter, and in lateral view is reniform with convex dorsal and coneaye
ventral surface. The hypocone exceeds the epicone in length and in width. The epicone is
hemispherical in ventral view with symmetrically rounded sides. Its length is 0.4 of the total
length of the body. The hypocone is hemispherical posteriorly, widest in the central part and
tapering anteriorly at the girdle, in ventral view.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 233

The girdle is slightly premedian, its distance from the apex about 0.4 of the total length of
the body. It forms a complete circle around the body and is deeply impressed. The sulcus
extends from the girdle to the antapex in a straight line. The longitudinal flagellum arises at
the proximal end of the suleus.

The nucleus is not figured by Saville-Kent (1880-82). The cytoplasm is clear and trans-
parent and usually contains numerous spherules varying in size. Nutrition is holozoic. Saville-
Kent observed it actively devouring Hetcromita and other monads in the same culture, the
organisms being taken in at the sulcal region near the girdle.

Dimensions.—Leneth, 30; transdiameter, 28; dorsoventral diameter, V7.

OccuRRENCE.—Figured by Saville-Kent (1880-82) from an infusion of hay
and sea water made at St. Heliers, Jersey, in February. One month later the
culture was abundantly filled with these small holozoic forms.

Comparisons.—This species finds its nearest relative, apparently, in G.
cinctum, a species with ochraceous chromatophores. G. cinctum, however, does
not show the same dorsoventral compression of the body found in this species,
and has a smaller epicone.

Gymnodinium minor Lebour
Text figure X, 12
Gymnodinium minor Lebour (19176), p. 192, fig. 8.

Dracnosts.—A minute species with stout ovoidal body, its length 1.16 trans-
diameters; girdle displaced by narrowing its furrow; sulcus extending from
the girdle to the antapex. Length, 28. Plymouth Sound, England, May-July.

DeEscRIPTION.—The body is rotund ovoidal with the widest part anterior, its length 1.16
transdiameters at the widest part. The epicone exceeds the hypocone in length by about 0.5 of
its own length. It is subhemispherical in shape with a length on the left and right sides of the
suleus of 0.46 and 0.6 respectively of the total length of the body. The hypocone is slightly
narrower than the epicone with truncate antapex.

The girdle is behind the midregion of the body, joining the sulcus about 0.64 of the total
length of the body from the apex. On the right side the furrow becomes contracted to less than
0.3 its own width, giving an appearance of displacement contradicted by the posterior borders
of the girdle. It is wide on the left side of the body, about 0.06 transdiameters, and deeply
impressed. The sulcus extends from the girdle to the antapex, widening as it passes posteriorly.

The nucleus is an ellipsoidal body near the center of the body. Coarse chromatin strands
extend obliquely along its major axis. Its major and minor axes are about 0.5 and 0.25 trans-
diameter in length respectively. Several green food masses were present in the anterior part of
the body.

Drmensions.—Lenegth, 28”; transdiameter, 24”; axes of nucleus, 12 and 6-.

OccURRENCE.—It has been figured by Lebour (1917)) from Plymouth Sound,
England, from collections made from May to July.

ComPaRIsONsS.—This species is nearest to G. ovulum sp. nov. (fig. X, 15),
but differs from it in the less spheroidal form (probably distended), greater
displacement of the girdle, and lack of sulcus on the epicone.

234 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Gymnodinium mirabile Penard
Text figure X, 18

Gymnodinium mirabile Penard (1891), pp. 11, 14, 16, 22, 23, 24, 25, 30, 56, pl. 5, figs. 1-7.
7. mtrabile, Imhof (1892), p. 175.

. mirabile, Lemmermann (1900), p. 116; (1902), p. 260; (1910), p. 613, figs. 15-16; pp.
618, 624.

. mirabile, Levander (1901), p. 6.

G. mirabile, Schilling (1913), p. 16, fig. 14.

RR

R

DracNnosis.—Medium large species with subovoidal body, dorsoventrally
flattened, its length 1.28 transdiameters; girdle displaced about its own width;
sulcus short on epicone and extending to antapex; chromatophores green, yellow
or brown. Length, 90#. Lake Geneva, Switzerland.

DescripTioN.—The body is stout, subovoidal, with broad apices, widest below the middle, its
length 1.28 transdiameters at the widest part. The epicone exceeds the hypocone in length by
about 0.18 its own length. It is campanulate with broad apex, and a length on the left and right
sides of 0.5 and 0.54 respectively of the total length of the body. The hypocone is slightly
broader than the epicone, with a broad antapex which is truncate or notched.

The girdle is slightly behind the median part of the body and is displaced posteriorly about
its own width. The furrow is narrow and is deeply impressed with high rounded borders. The
sulcus invades the epicone for about half its length and extends posteriorly to the antapex.

The nucleus is a small, ellipsoidal body in the middle of the hypocone filled with coarse,
chromatin strands. Its major and minor axes are about 0.35 and 0.28 transdiameter in length
respectively. The peripheral zone of cytoplasm is filled with elongated, rodlike chromatophores,
radially arranged, and green, yellow, or brownish in color.

Diuenstons.—Length, 90“; transdiameter, 65; axes of nucleus, 20“ and 25p.

OccuRRENCE.—This species was figured by Penard (1891) from Lake Geneva,
Switzerland.

RELATIONSHIPS.—This species is close to G. uberrimum (Allman), described
by Penard (1891) as G. mirabile var. rufescens, but differs from it in propor-
tions, being a relatively longer form with greater displacement of the girdle.

Gymnodinium monadicum (Perty) Saville-Kent
Text figure BB, 7

Peridinium monadicum Perty (1852), p. 162, pl. 7, fig. 15.
Gymnodinium monadicum Saville-Kent (1880-82), pp. 443, 444.

Description.—A minute form with ovoidal to ellipsoidal body, widest anteriorly, with
rounded apices. Epicone is much wider than the hypocone with the girdle slightly postmedian.
The color is green with a small, red pigment spot. Length, 16u. Fresh water from the Bernese
Alps, Switzerland.

SynonyMy.—Figured by Perty (1852) as Peridinium monadicum, it was
placed in the genus Gymnodinium by Saville-Kent (1880-82) as G. monadicum.
He considers this identical with G. vorticelli (our fig. X, 29), described by Stein

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 235

(1878). Stein’s species differs in its proportions and in the lack of a red pig-
ment spot. The ventral face of Perty’s form has not been figured, hence that
part of the organism cannot be compared with G. vorticella. Until further
work has established its definite morphological characters, this form must be
considered as a doubtful species not identifiable with existing data.

Gymnodinium monas (Ehrenberg)

Peridinium monas Ehrenberg (1840), p. 201; (1845), p. 18.

Heteraulacus ? monas Diesing (1850), p. 101.

Heteroaulax ? monas Diesing (1866), p. 95.

Peridinium monas, Claparéde and Lachmann (1858-61), p. 406.

P. monas, Maggi (1874), p. 118; (188Ga), pp. 9, 13; (1880b), pp. 309, 313.
P. monas, Stein (1878), p. 60.

P. monas, Saville-Kent (1880-82), p. 444.

Ehrenberg (1840) has described as Peridinium monas an organism which
Saville-Kent (1880-82) considered as possibly identical with Gymnodinium
marinum. Khrenberg’s description, without figures, hardly furnishes an
adequate basis for the systematic allocation of this small form. He has de-
scribed it as very small, obtuse, without horns, and remarkably social, its
diameter 43» and occurring in the Baltic Sea. The absence of a theca would
remove it from the genus Peridinium, but the lack of further data leave it
permanently indeterminable.

Gymnodinium multilineatum sp. nov.
Plate 5, figure 59; text figure Y, 18

Dracnosis.—A rather large species, with symmetrical, broadly fusiform
body, apex rounded, antapex more contracted, bullet-shaped, its length about
2 transdiameters, both with minute points; girdle slightly displaced; surface
with fine striae, about 50 on one face; colorless; nucleus central. Length, 108+.
Pacifie off La Jolla, California, July, August.

Description.—The body is broadly fusiform, perfectly symmetrical, circular in cross-section,
its length 2.25 transdiameters. The epicone is about 1.66 of the length of the hypocone, and 0.9
transdiameter in length, rotund ellipsoidal, apex broadly rounded, with a minute apical point.
The hypocone is 1.35 transdiameters in length, shaped like the nose of a bullet, the antapex
contracting symmetrically to a sharp point.

The girdle is 0.4 of the total length of the body from the apex, almost in transverse plane,
both proximally and distally the ends deflected for less than their width posteriorly. The distal
end in one individual was displaced posteriorly about its own width with almost no overhang
of the proximal end over the distal one. The transverse furrow is deeply impressed, and exea-
vated below the sharp-edged lips. The flagellar pore of the transverse flagellum is an elliptical
opening just posterior to the proximal end of the furrow on the left side of the longitudinal
furrow. The transverse flagellum is a thin, narrow ribbon almost completely encircling the

236 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

body. The suleus extends anteriorly on the epicone for 0.85 of its length, and posteriorly on
the hypocone for little more than 0.33 of its length, fading out at the pore of the longitudinal
flagellum at its posterior end. It is linear, lies in the median plane, and forms a narrow, uniform
channel about half the width of the transverse furrow, flaring slightly only in the anterior part.

The surface is characteristically marked with very fine, delicate, close-set longitudinal striae
of uniform intervals on both epicone and hypocone. These anastomose or die out distally so
that the uniformity of interval is maintained throughout the whole surface. At the girdle there
are about fifty of these striae on one face of the body. Beneath the pellicle there is a thin layer
of faintly developed slender rodlets about 0.06 transdiameter in length. These stand perpen-
dicularly to the surface except in the antapex, where they are somewhat larger and are crowded
into the narrowing apex. Seattered spheroidal refractive granules lie just beneath this layer of
rodlets.

The body as a whole is quite translucent and of a greyish color tinged faintly with greenish
yellow. It is crowded with numerous spherical pinkish vacuoles 0.06 to 0.12 transdiameter in
diameter. The broadly ellipsoidal nucleus lies just beneath the girdle with its long axis inclined
to the right anteriorly. It is about 0.5 transdiameter in length in its greatest axis, and is filled
with a coarse, moniliform chromatin thread. No chromatophores and no pusules could be
detected. A few small refractive granules were clustered near the nucleus. Probably holozoie.

Druensions.—Lenegth, 108; transdiameter, 50; greatest diameter of
nucleus, 26+.

OccURRENCE.—This was taken July 5, 1917, with a No. 12 silk net, in a haul
6 miles off La Jolla, California, from 80 meters to the surface and in a surface
temperature of 21°4 C. On July 11 it was taken with a No. 25 silk net, 4 miles
off La Jolla, in a haul from 80 meters to the surface, and on July 27 and on
August 21 at the same place and under approximately the same conditions.

Comparisons.—The structure of the girdle places this species in the genus
Gymnodinium, but the striate surface and rodlets recall those of many species
of Gyrodinium, such as G. acutum. It belongs to the subgenus Lineadinium,
but has no near relatives in form, proportions, or size. It is the most finely
striated species in the genus and appears to be a unique and isolated type.

Gymnodinium multistriatum sp. nov.
Plate 4, figure 37; text figure Y, 1

DrtaGNnosis.—A medium sized species with biconical body, its length 1.47
transdiameters; girdle submedian, displaced 0.25 transdiameter; sulcus ex-
tending from apex to antapex ; surface finely striate; color grey green and yellow
ochre. Length, 100e. Pacific off La Jolla, California, August.

DescrwtioN.—The body is rotund biconical, asymmetrical, almost rhomboidal in shape, nearly
circular in cross-section, with rounded apices, its length 1.47 transdiameters at the widest part,
which is equatorial. The epicone is slightly larger than the hypocone in size, its length being
greater by 0.1. It has the form of a cone of about 65°, with a blunt apex and broad base, its
right side about 0.23 longer than its left side. The right side is slightly more convex than the
left. It has a length on the left and right sides of 0.43 and 0.59 respectively of the total length
of the body. The hypocone forms a cone of about 70° with its left side longer than the right
and a blunt antapex excavated on the ventral side by the suleal notch. Both sides are only very
slightly convex.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 237

The girdle is submedian, its proximal and distal ends having a distance from the apex of
0.43 and 0.59 respectively of the total length of the body. It makes a slight anterior deflection
in the first 0.12 of its course, beyond which it takes a descending left spiral course around the
body, displaced posteriorly at its distal end 0.25 transdiameter. The furrow is wide, about 0.07
transdiameter, and relatively shallow, with smooth borders. The suleus extends from the apex
to the antapex in a nearly straight line. The furrow is slightly narrower than the girdle and
lies in a wide trough (about 0.5 of the transdiameter in the middle of the body) which extends
down the ventral face of the organism, deepest in the girdle region and posteriorly, fading out
near the apex. Beyond the posterior pore the sides are deflected laterally, forming a wide
excavation at the antapex. The anterior flagellar pore opens near the lower border of the girdle
at its proximal junction with the sulcus, the posterior pore a short distance anterior to the
antapex.

The nucleus is spherical and is located just below the equatorial plane on the left side of the
body. Its chromatin contents could not be analyzed. Its axis is 0.35 transdiameter in length.

The cytoplasm is finely granular and densely filled with large vacuoles, pinkish grey in color.
In the peripheral zone are numerous blue-green oil droplets and dark, refractive granules,
evidences of holozoic nutrition. A small sacklike pusule opens into each flagellar pore. The
surface is striate with closely placed, equidistant, blue-green striae. The number of striae on
the hypocone exceeds the number on the epicone by about 0.25. The color of the cytoplasm is
pearl grey with minute stippling of yellow ochre at the apices and near the girdle.

Divenstons.—Length, 100/; transdiameter, 68°; transdiameter of nucleus,
24h, ;

OccuRRENCE.—A single individual was taken August 21, 1917, with a No.
25 net, 5 miles off La Jolla, California, in a haul from 83 meters to the surface.

Comparisons.—In the fineness and number of surface striae this species
closely resembles G. multilineatum sp. nov. (fig. Y, 18), G. radiatum sp. nov.
(fig. Z, 9), and G. rubrum sp. nov. (fig. Y, 4) in the relatively wide displacement
of the girdle. In the latter respect these two species approach the Gyrodinium
tvpe of girdle. It belongs in the subgenus Lineadinium in a group of subbi-
conical to broadly ellipsoidal, rather finely striate species, including G. situla,
G. diploconus, and G. radiatum, and has the maximum degree of displacement
of the girdle in this group.

Gymnodinium musei Danysz
Text figure X, 3
Gymnodinium muset Danysz (1887), pp. 288, 239.
G. musaet, Pouchet (1887), pp. 89, 104, pl. 10, fig. 6.
G. musci, Entz, Jr. (1909), pp. 262, 268. Lapsus.
7. muset, Lemmermann (1910), p. 565, figs. 18-15, pp. 618, 619, 622.

on

DraGnosis.—A minute species with broad body, its length 1.22 transdiam-
eters; girdle posterior, without displacement; sulcus on hypocone only; two
minute red pigment spots. Length, 20. Fresh-water pools, Paris, France.

Description.—The body is broadly ellipsoidal in ventral view with broad apices, dorso-
ventrally compressed, its length 1.22 transdiameters at the widest part. The epicone greatly
exceeds the hypocone in size, its length being greater by 0.53. It is elongate hemispherical in

238 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

shape, flaring posteriorly, with a length of 0.69 of the total length of the body. The hypocone
is rounded truneate, slightly notched by the distal end of the sulcus.

The girdle is posteriorly placed, its distance from the apex being 0.69 of the total length of
the body. It forms a complete circle around the body, the ends meeting without displacement.
The furrow deeply undercuts the anterior border of the epicone and is almost obscured by the
lip thus formed. The suleus extends from the girdle to the antapex. The flagella were not
figured by Pouchet (1887), whose figures form the basis of this description.

The interior of the body is filled with numerous spherules, among which the nucleus is not
distinguished. Two minute red pigment spots are found ventrad posterior to the junction of
the girdle and suleus. Pouchet (1887) figures four schizonts within an ellipsoidal cyst approxi-
mately the size of the free flagellate. In his figure 6 D, plate 10, Pouchet has figured a form
which evidently does not belong to the species, G. musei, differing too greatly in proportions
from his figures 6 A and 6 B to have any close relationship with them.

Dimenstons.—This was described but not figured by Danysz (1887) from
pools at Paris, France. In the same year Pouchet figured this form in material
taken from the same place.

SynonyMy.—Entz (1909) quotes Danysz’s description of this species with
the species name spelled musci, a lapsus for muset.

Comparisons.—The description and figures of this species are so inadequate
that comparisons are tentative. It appears to be unique in the excessively large
epicone, which has nearly three times the volume of the hypocone. The nearest
approach to these proportions appears in G. vorticella Stein (fig. X, 29) and
G. dissimile sp. nov. (fig. X, 32). The stigma in all of Pouchet’s figures (1887)
is double, consisting of a larger and smaller parallel moiety, a condition of this
organ unique in this genus.

Gymnodinium ovulum sp. nov.

Plate 5, figure 58; text figure X, 15

Dracnosis.—This is a minute species with spheroidal body, its length and
transdiameter subequal; girdle submedian, without displacement, suleus short
on both epicone and hypocone; colorless. Length, 28. Pacific off La Jolla,
California, July, August.

DescripTion.—The body is spheroidal, cireular in cross-section, apices broad and rounded,
its length and transdiameter equal. The hypocone is very slightly larger than the epicone. The
epicone is subhemispherical in shape, its sides less convex than those of the hypocone. The
apex is broad and smoothly rounded. It has a length of 0.44 of the total length of the body.
The hypocone is hemispherical in shape with smoothly rounded sides and broad antapex.

The girdle is submedian in position, its distance from the apex 0.44 and from the antapex
0.46 of the total length of the body. The furrow is wide, about 0.1 transdiameter, and deeply
impressed, its sides gradually curving outward to the surface of the body. The suleus is a
shallow trough beginning midway between girdle and apex and extending to within a short
distanee of the antapex. It follows a slightly sinuous course, enlarging at the girdle, narrowing
toward both ends. The anterior flagellar pore opens at the junction of the girdle and suleus,
the posterior pore a short distance below.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 239

The nucleus is a relatively large, ellipsoidal body filled with coarse, moniliform chromatin
strands. It is located on the left side of the anterior part of the body. Its major and minor
axes are 0.53 and 0.42 transdiameters respectively.

No pusules were observed. The cytoplasm is finely granular and usually contains one or
more large food bodies. The one figured contained a single large, reddish brown mass, nearly
filling the entire body. Other individuals showed one to several food bodies yellow ochre in
color. Nutrition is holozoic. The color of the cytoplasm is pearl grey. It is made conspicuous
under the microscope by the presence of the brightly colored food bodies.

Divenstons.—Length, 28; transdiameter, 28; axes of nucleus, 15» and 12.

OccuRRENCE.—This was observed July 9, 1914, in a surface haul taken near
the shore at La Jolla, California. In July and August, 1917, it was frequently
met with in most of the hauls made. The one figured was taken July 21, with
a No. 25 net in a surface haul at the end of the pier.

Comparisons.—The group of minute species represented by G. ovulum, G.
minor, G. vorticella, G. marinum, and a few fresh-water forms must be regarded
only tentatively as good species. The similarity of these forms to the small
Gymnodinium found in eysts, evidently the products of multiple fission, leads
one to suspect that we may be dealing here with a stage in the life history and
not with distinct species. The great difficulty in following the development of
these extremely delicate organisms leaves this an open question at the present
time. For the sake of convenience, therefore, they are held as valid species
until their development has been followed out more fully. Among marine
species @. ovulum is nearest G. minor Lebour (fig. X, 12) and G. flavum sp. nov.
(fig. X, 7), but is more nearly spherical than either and lacks the chromato-
phores of the latter. The distension of the body by the food balls is possibly a
factor in its spheroidal contour.

Gymnodinium pachydermatum sp. nov.
Plate 3, figure 32; text figure AA, 5

DraGNosts.—This is a large species of robust habit, body broadly ellipsoidal,
its length 1.53 transdiameters; epicone hemispherical; girdle submedian; dis-
placed twice its own width; sulcus invading the epicone, extending to the anta-
pex: differentiated ectoplasm; color orange green. Length, 160", Pacific off
La Jolla, California, June, July.

Description.—The body is of robust habit, broadly ellipsoidal with broad apices, nearly
circular in cross-section, with protuberant girdle, its length 1.53 transdiameters at the widest
part. The epicone and hypocone are subequal in length, but the transdiameter of the distal
part of the epicone is slightly greater than the greatest transdiameter of the hypocone. The
epicone is broadly dome-shaped, hemispherical anteriorly and flaring slightly at the girdle. The
apex is broad and symmetrically rounded. The epicone has a length on the left and right sides
of 0.4 and 0.53 respectively of the total length of the body. The hypocone is somewhat narrower
than the epicone with sides subparallel anteriorly and rounded posteriorly with the antapex
deeply notched by the distal end of the sulcus.

240 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The girdle is submedian, its proximal end meeting the suleus at a distance from the apex of
0.4 of the total length of the body. It sweeps around the body in a descending left spiral
direction, displacing the distal end about twice the width of the girdle. The furrow is wide,
about 0.05 transdiameter, and is deeply impressed with overhanging shelflike borders, its upper
lip cut under and the lower one gradually rounded. The suleus begins midway between the
girdle and apex and extends posteriorly to the antapex as a deep trough. In the antapical
region the borders are widely deflected and the trough deepened, forming a deep excavation
notching the antapex. The anterior flagellar pore opens at the junction of the proximal end
of the girdle and suleus, the posterior pore a short distance below the distal junction.

The nucleus is a large spherical body in the central part of the hypocone near the left of the
suleus in ventral view. Its axis is about 0.32 transdiameter.

No pusules were observed in the individual figured. The cytoplasm is granular and generally
contains many cell inclusions. In the epicone was an irregularly shaped food mass, pale lumiére
green in color near which was a group of 6 very large spherical bodies of varying shades of
cream color and yellowish green. Around these were smaller vacuoles filled with the pink fiuid
usually present in the pusules, a number of which were also scattered through the hypocone.
Behind the distal junction of the girdle and suleus was a rounded body, dark green in color.
Radiating out from this was a group, 10 in number, of long, slender, tapering green rodlets.
These varied in length from 224 to 40x. The differentiated ectoplasm was remarkably clear
and striking even under the lowest power of the microscope, where it had the appearance of a
wide, clear band surrounding the organism. A closer examination showed it to be composed of
two layers, a hyaline double-contoured layer superimposed upon which was a somewhat narrower
one of alveoli, the rounded outer surfaces of which gave a ridged, uneven appearance to the
outline of the body. The inner layer, like that in G. dogieli, was yellow, the alveolar orange in
color on the hypocone shading to lighter tones of the same on the epicone. The whole color effect
was rich and striking.

Divensions.—Length, 160; transdiameter, 104; axis of nucleus, 34+.

OccURRENCE.—This was taken June 27, 1917, with a No. 12 silk net, in a
haul 6.1 miles off La Jolla, California, from 120 meters to the surface and in a
surface temperature of 20° C. Another individual was observed on July 11
with a No. 25 silk net, ina haul 4 miles off La Jolla, from 80 meters to the surface
and in a surface temperature of 20° C. On July 20 a third individual was taken
6 miles off La Jolla with the same apparatus and at the same depth, in a surface
temperature of 20°5 C,

Comparisons.—This, with G. dogieli sp. nov., G. amphora sp. nov., and G.
abbreviatum sp. nov. (figs. AA, 8, 6; fig. Z, 7), form the most striking repre-
sentatives of the subgenus Pachydinium. They are closely related with the
same differentiation of ectoplasm and endoplasm and are remarkably beautiful
in coloring, the reproductions of which fail to do them justice. They are the
most highly organized of the genus, and form the culmination of a line of
development which may be traced from the simpler forms. This species has a
posterior sulcal notch not present in the others named, and a greater displace-
ment of the girdle.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 241

Gymnodinium palustre Schilling
Text figure X, 16

Gymnodinium palustre Schilling (1891), pp. 248, 277, 278, pl. 9, figs. 11-13, pl. 10, fig. 11;
(ICIS), fos UG. tare, alle

G. palustre, Ludwig (1898), p. 299.

G. palustre, Mez (1898), p. 216, pl. 6, fig. 285. Based on Schilling’s (1891) figures.

G. palustre, Lemmermann (1889), p. 126; (1900), p. 116; (1901), pp. 67, 69, 72; (1902),
p. 260; (1905), p. 159; (1910), pp. 613, 618, 620, figs. 15, 16.

G. palustre, Schénichen and Kalberlah (1910), p. 232; (1909), p. 252. Based on Schil-
ling’s (1891) figures.

G. palustre, Bolochonzew (1903), pp. 7, 59.

G. palustre, Wesenberg-Lund (1904), pp. 106, 107 (in part = G. zacharias?).

G. palustre, Entz (1910), p. 158.

G. palustre, Guyer (1910), pp. 365, 377.

G. palustre, Kolowitz (1911), pp. 314, 315, 325, 326, 327, 341, 357, pl. 6, fig. 2 (in part =
G. zachariast), pl. 10, fig. 4; (1912), p. 214.

Not Gymnodinium palustre, Zacharias (1899) ; Dogiel (1906) ; Klebs (1912) ; nor Fauré-
Fremiet (1914) (—G. zachariasi (Zach.) Lemm.).

Dracnosis.—A small species with ellipsoidal body, its length 1.12 transdiam-
eters; girdle without displacement; yellow to brown chromatophores. Length,
44u, Fresh-water ponds and swamps in Germany and Switzerland in summer.

DEscrIPTION.—Body stout ellipsoidal, the anterior end rounded, the posterior truncate, its
length 1.12 transdiameters at the widest part. The epicone exceeds the hypocone in length by
0.4 its own length. It is bell-shaped with rounded apex. The hypocone is broadly rounded with
the antapex more or less truncate.

The girdle is postmedian in position, its length from the apex about 0.4 of the total length .
of the body. The furrow is deeply impressed, with overhanging borders. A sulcus is not figured
by Schilling (1891). The nucleus is located in the central part of the body. Round, yellow to
dark brown chromatophores are scattered through the peripheral zone of cytoplasm.

Divensions.—Lenegth, 44; transdiameter, 37.54. As figured by Schilling
(1891, pl. 10, fig. 11; 1913, fig. 11) the transdiameter is 15», though not so given
in the text.

OccURRENCE.—This species was found by Schilling (1891) in ponds and
ditches in Germany. Guyer (1910) notes its abundance in the summer plankton
in the Greifen Lake in Switzerland. Lemmermann (1902) records it from
Lake Ploén, and (1905) from Oppeln, Germany. Bolochonzew (1903) found it
occurring in the summer in the Volga River, Russia, and Wolkwitz (1911) in
Taken, Russia, and Remscheid, Germany, throughout the year.

Comparisons.—This species is near G. zachariasi in its proportions, but is
somewhat stouter. The chromatophores also appear to differ, being rodlike in
the latter and more rounded in G. zachariasi. No pseudopodia have been noted
in this species.

242 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Gymnodinium paradoxum Schilling
Text figure X, 26
Gymnodinium paradoxum Schilling (1891a), pp. 278, 279, pl. 10, fig. 13; (1913), p. 18,
fig. 15.
G. paradoxum, Ludwig (1898), p. 299.
G. paradoxum, Mez (1898), p. 216.
G. paradoxum, Schonichen and Kalberlah (1900), p. 231; (1909), p. 252.
G. paradoxum, Lemmermann (1900), p. 116; (1902), p. 260; (1903@), pp. 86, 88, 90, 108;
(1905b), p. 159; (1908), pp. 170, 180; (1910), pp. 565, 618, 620, 626, fig. 22.
G. paradoxum, West and West (1906), pp. 91, 92; (1909«a), p. 187.
G. paradoxum, Klebs (1912), p. 384.
G. paradoxum, West (1916), p. 51.

Dracnosis.—A minute species with a broadly ellipsoidal body, its length
1.12 transdiameters; girdle slightly postmedian, without displacement; sulcus
very short; dark brown chromatophores. Length, 40#. Fresh water, Scottish
and English lakes, German lakes, February to April, near Basel, Switzerland.

Description.—The body is rotund ellipsoidal, with broad apices, widest in the middle, its
length 1.12 transdiameters at the widest part. The epicone exceeds the hypocone in size, its
length being greater by 0.27. It is elongated hemispherical in shape, with broad apex. Its
length is about 0.57 of the total length of the body. The hypocone is subhemispherical in shape
with smoothly rounded antapex.

The girdle forms a complete circle around the body slightly posterior to the midplane. It is
rather broad and comparatively shallow. Distinct outlines for the girdle and suleus are not
given in Schilling’s figure (1891a@). The transverse and longitudinal flagella arise near together
at the junction of the girdle and suleus.

The nucleus is not figured by Schilling. The central part of the cytoplasm is filled with
dark brown chromatophores. On the ventral side, immediately below the ends of the girdle, is a
relatively large, ellipsoidal pigment spot, the color of which is not indicated, though presumably
of a red color.

Dimensions.—Length, 40; transdiameter, 34.5.

OccURRENCE.— It was figured by Schilling (1891a@) from fresh-water swamps
and ponds near Basel, Switzerland. It is frequently found among vegetation
and in the plankton. Other records of its occurrence are as follows: West
and West (1909) from the Scottish and Enghsh lakes and Lemmermann (1903a,
1905D), in ponds in Germany, from February to April.

SynonyMy.—West and West (1906) mention a variety of this species, G.
paradoxum var. major, from Lough Currane, County Kerry, Ireland, named
by Lemmermann. The only data given are its length, 66—75z, and transdiameter
of 61-674. It is not figured. Its position and relationship thus cannot be de-
termined, since the proportions of length and transdiameter differ from those
of G. paradoxum.

ComPparisons.—This species is closely related to G. rotundatum and G. viride
in the subgenus Gymnodinium, but it is larger and more rotund than these
species, differing also from the former in the presence of the eyespot. In size
and shape it is near G. wherrimum, but the large eyespot and indistinctness of
the chromatophores serve to separate it from that species.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 243

Gymnodinium pseudonoctiluca Pouchet
Text figure X, 35

Gymnodinium pseudonoctiluca Pouchet (1885a), pp. 71-75, 76, 82, pl. 10, figs. 34-37;
(1892a), p. 87; (18926), pp. 143-150, pl. 11, figs. 1-14; (1894), p. 169.

G. pseudonoctiluca, Biitschli (1879), pp. 1078, 1082.

G. pseudonoctiluca, Lemmermann (1899), p. 359; (1910), p. 619.

G. pseudonoctiluca, Ostenfeld (1903), p. 561.

G. pseudonoctiluca, Mingazzini (1904), pp. 98, 99.

G. pseudonoctiluca, Paulsen (1908), pp. 97, 99, fig. 135. After Pouchet (1892).

G. pseudonoctiluca, Jorgensen (1912), p. 10.

G. pseudonoctiluca, Fauré-Fremiet (1914), pp. 41, 48, 44, 45, fig. 11. After Pouchet
(1892b).

Not Gymnodinawm pseudonoctiluca, Lebour (1917b), p. 188, fig 3 (= G. fulgens nom. sp.
noy.).

Dracnosis.—A large species with long, subevlindrical body, its length 2.5
transdiameters; girdle anteriorly located, turning posteriorly on ventral side;
sulcus extending from girdle to antapex; color greenish. Length, 116+.
Atlantic, Arctic.

DescripTION.—The body is long, subcylindrical, the anterior end conical, the posterior
rounded, its length 2.5 transdiameters. The epicone is greatly exceeded by the hypocone in
extent, having an average length of less than 0.3 the length of the hypocone. The length of the
epicone on the dorsal side is 0.18 of the total length of the body. It extends posteriorly on the
ventral side in a slender point with a length of about 0.55 the total length of the body. It is
subeonical anteriorly (about 55°), flaring widely at the base. According to Pouchet (1892b),
the entire epicone is retractile and may almost completely disappear within the body. The
hypocone is long cylindrical or enlarged posteriorly. Its length on the dorsal side is about 0.78
of the total length of the body.

The girdle is placed far anteriorly, its distance from the apex on the dorsal side being 0.18
of the total length of the body. Both ends turn posteriorly, meeting at a point slightly posterior
to the equator. The furrow is narrow, relatively shallow, with overhanging borders. The suleus
is not well defined in any of Pouchet’s (1885a, 1892b) figures. It apparently extends from the
girdle to the antapex.

The nucleus is large and spheroidal, and is found near the center of the body. It is nearly
surrounded by a granular mass dark greenish brown in color, giving a dense appearance to the
central portion of the body. The remainder of the cytoplasm forms radiating strands extending
out from the central mass to the periphery, separated by vacuoles. Seattered through the
peripheral layer are granules green and brown like those surrounding the nucleus. Anteriorly
the cytoplasm has a yellow or-orange color.

The most striking and at the same time puzzling feature of this organism is the seemingly
temporary or evanescent protrusion which resembles a tentacle. It is rather difficult to har-
monize the yarious figures of this species given by Pouchet (1885a, 1892b) and his own deseription
does not clear up the difficulties. The girdle in figures 2 and 4, plate 11 (18926), with its
posterior turn on the dorsal side, has no apparent relation to the same structure in figures 3
and 7 on the same plate, in which the girdle passes across the dorsal side in a direction at right
angles to the long axis of the body. Variations to this extent in one species in the position of
the girdle are not known elsewhere in the Dinoflagellata. The tentacle itself apparently arises
from the suleal region near the posterior end of the body as a long, slender, protoplasmic extension

244 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

which is not motile, as is the flagellum. Its length is about equal to the dorsoventral diameter or
less. It is possible that he is here confusing two distinet forms or that we have in this species an
extraordinary mobility in the form of the body.

Dnrenstons.—Length, 100—200+; transdiameter, 46-80.

OccURRENCE.—This species was figured by Pouchet (1885a) from the
Atlantic off Conearneau, France, in June, and, at later dates (1892b), from the
Atlantic off the Faroe Islands in August, and, in 1894, from the Arctic Ocean
near Spitzbergen in August.

SynonyMy.—Lebour (1917)) has figured a form which she calls Gymno-
dinitum pseudonoctiluca Pouchet. The differences between the two forms are
too great, however, to place it with Pouchet’s species. The girdle forms a com-
plete circle at the anterior end, instead of turning posteriorly on the ventral
surface, where, in G. pseudonoctiluca, it reaches posteriorly beyond the middle
region of the body. Lebour’s species also possesses bright vellow chromato-
phores. It is therefore given species rank, with the name G. fulgens nom. sp.
noy. Pouchet’s record (1894) of this species from the Arctic Ocean at a tem-
perature of 2°-3° C may be looked upon with suspicion. It seems improbable
that the Gulf Stream could carry, without change, organisms as frail and
delicate as these from the warm semitropical waters to the cold Arctic Ocean.

Comparisons.—In its cytoplasmic structure G. pseudonoctiluca recalls the
conditions found in G. pachydermatum, G. dogieli, and G. amphora (figs. AA,
5, 1, 6). It differs greatly, however, from that group in its lack of a differ-
entiated ectoplasm. In the possession of this tentacle-like protrusion this
species might seem to be a connecting link between this group and the Nocti-
lucidae. However, in so far as our knowledge goes, it appears that we are here
dealing with a protoplasmic extension of the edge of the sulcus of a temporary
nature, perhaps like that figured by Schiitt (1895) for G@. rete, and by Zacharias
(1899) for G. zachariasi. It is a tentacular pseudopodium, and not a flagellum
transformed into a tentacle, and is therefore not homologous with the tentacle
of Noctiluca.

Gymnodinium punctatum Pouchet
Text figure BB, 18

Gymnodinium punctatum Pouchet (1887), pp. 105-107, pl. 10, fig. 7.
G. punctetum, Lemmermann (1899), p. 359.
G. punctatum, Paulsen (1908), p. 108.

DescripTION.—This is a minute form with broadly ellipsoidal body in ventral view, compressed
dorsoventrally to 0.54 transdiameter, its length 1.33 transdiameters. The girdle is median in
position, dividing the body into subequal parts. The epicone is hemispherical, the hypocone
slightly notched at the antapex. The nucleus is a large, chromatin-filled body in the epicone. A
minute red-pigment spot is present near the posterior part of the body. The sulcus and course
of the girdle were not figured by Pouchet (1887). Length, 10u. Atlantic off Concarneau, France.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 245

Pouchet’s description of this form leaves the important species character-
isties, the relation of girdle and sulcus, undetermined. Paulsen (1908) suggests
the possibility of this being a swarm spore. It differs sufficiently from the
other forms described to be regarded only tentatively as a valid species. Its
exceptionally small size requires verification.

Gymnodinium puniceum sp. nov.

Plate 5, figure 51; text figure Z, 5

DraGnosis.—This is a large species with subovoidal body, its length 1.57
transdiameters; girdle premedian, without displacement; sulcus extending
from near apex to antapex; surface sparsely furrowed; color, onion-skin pink.
Length, 110#. Pacific off La Jolla, California, August.

DeEscripTioN.—The body is subovoidal in shape, with broad apices, widest posteriorly, its
length 1.57 transdiameters at the widest part. The hypocone greatly exceeds the epicone in size.
The epicone forms a slightly irregular dome with broad rounded apex. ‘The left side is more
convex than the right, both are slightly irregular. Its length is about 0.32 of the total length
of the body. ‘The hypocone is barrel-shaped, with broad antapex. Its greatest transdiameter at
about its middle equals its length. The right side is convex, the left concavo-convex anteriorly
and convex posteriorly. The suleal notch is deflected to the right, throwing the two lobes formed
by its borders on the dorsal side of the body, to the right of the midplane of the body in ventral
view.

The girdle is premedian in position, its distance from the apex about 0.32 of the total length
of the body. It forms a complete circle around the body. The furrow is wide, about 0.07 trans-
diameter, and is deeply impressed, with its anterior lip deeply undereut and its posterior border
gradually rounded. Its borders are irregular, following the curves of the surface. The right
end of the girdle is somewhat wider than the left. The suleus begins near the apex and extends
posteriorly in a slightly sinuous line to the antapex. It forms a broad channel which fades out
near the apex, widens at the girdle and deepens posteriorly, with the overhanging borders
narrowing its apparent width near the posterior pore. Near the antapical region the borders
become widely deflected and extend around to the dorsal surface of the body, about the deeply
excavated antapex. The anterior flagellar pore is found at the junction of the girdle and suleus,
the posterior pore about 0.6 of the distance between that junction and the antapex.

The nucleus is ellipsoidal, its long axis parallel with the long axis of the body. It is situated
on the left side of the body, posterior to the girdle. Its major and minor axes are 0.51 and 0.32
transdiameter respectively.

A small sacklike pusule opens into the anterior flagellar pore. None could be detected at the
posterior pore. The cytoplasm is finely granular and is almost completely filled with variously
colored food bodies. The central part. is occupied by a single large mass of a dark color.
Surrounding this were smaller bodies and vacuoles of varying shades of grey, yellow ochre and
green, with a few small refractive spherules. Nutrition is holozoic. The general color of the
organism is onion-skin pink diffused through the eytoplasm, with a slight deepening of the color
anteriorly and in the central part of hypocone.

The surface of the body is marked by deep furrows, about 6 across the ventral face. The
surface between the furrows is raised into high, rolling ridges. The furrows disappear before
reaching the apices and girdle, but the ridges continue to the girdle and antapex, giving to the
borders of both a lobed appearance,

246 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Dimenstons.—Length, 110; transdiameter, 70“; axes of nucleus, 36 and 23+.

OccuRRENCE.—This species is represented by one individual taken August
6, 1917. with a No. 25 silk net 4 miles off La Jolla, California, in a haul from
60 meters to the surface and in a surface temperature of 21°2 C.

CoMPARISONS.—This species is unique in its coloring in the genus Gymno-
dinium. In its surface structure it recalls the conditions found in A. galbanum,
the surface being more irregular, however, with its high, rolling ridges, than
the latter species. Amphidinium cucurbita and Erythropsis scarlatina also
show the same tendency. It belongs in the subgenus Pachydinium, and repre-
sents the extreme form of sparse striation, with no near relations. The nearest
related species are Gymnodinium coeruleum and G. wilezeki Pouchet (fig. Z,
4, 8), but color and proportions clearly separate these from G. puniceum.

Gymnodinium pyrocystis Jorgensen
Gymnodinium pyrocystis Jorgensen (1912), p. 10.

Dracnosts.—A large species, stout, its length 1.6 transdiameters; girdle
placed far anteriorly with the ends on the ventral side bent posteriorly; color-
less. Length, 200. North Sea, September, November.

DescripTION.—The body is large, stout, its length about 1.6 transdiameters. The epicone is
small, about 0.2 of the length of the hypocone on the dorsal side. It is subconical with apex
blunt or truneate. The hypocone is large and broadly rounded, often broader and thicker at the
posterior end, truneate or notched with broadly round lobes.

The girdle lies far anteriorly on the dorsal side, both ends curving posteriorly on the ventral
side. The suleus extends from the region of the girdle to the antapex or passes around towards
the dorsal side. The nucleus is nearly spherical and is centrally located. The cytoplasm
contains an irregular central mass from which strands pass outward to the periphery where they
join. It is filled with numerous spherules of varying size, the largest of which are found in the
region of the girdle and at the apices.

Dimenstons.—Lenegth, 50-200; transdiameter, 30—-150+.

OccURRENCE.—This species has been described without a figure by Jorgensen
(1912) from the North Sea in September and November. He also records it
as moderately abundant along the west coast of Norway in autumn.

ComParisons.—This species appears to lie near G. fulgens (fig. X, 30) and
not far from the larger forms of Amphidinium such as A. vasculum.

Gymnodinium radiatum sp. nov.
Text figure Z, 9

Dracnosts.—A medium sized species with broadly ellipsoidal body in ventral
view, slightly flattened dorsoventrally, its length 1.26 transdiameters; girdle
slightly premedian, displaced about twice its own width; sulcus short on epicone,
extending to near antapex on hypocone; surface very finely striate. Length,
86u. Pacific off La Jolla, California, June.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 247

DescrIPTION.—The body is rotund, broadly elliptical in ventral view, dorsoventrally com-
pressed, with broad, rounded apices, its length 1.26 transdiameters at the widest part, its dorso-
ventral diameter about 0.88 transdiameter. The hypocone is slightly larger than the epicone,
its length being greater by 0.15. The epicone is hemispherical in ventral view with symmetrically
rounded sides. It has a length on the left and right sides of 0.33 and 0.48 respectively of the
total length of the body. The hypocone also has the form of a slightly elongated hemisphere in
ventral view with smoothly rounded sides subparallel anteriorly.

The girdle is slightly premedian in position, its proximal end joining the suleus at a distance
from the apex of 0.33 and its distal end 0.48 respectively of the total length of the body. It
follows a descending left spiral course around the body, its distal end displaced posteriorly about
two widths of the girdle. The furrow is wide, about 0.08 transdiameter, and is shallow with
smooth borders. The sulcus invades the epicone but a short distance. It extends posteriorly on
the hypocone in a straight line to near the antapex. The trough is wide and about 0.14 of the
dorsoventral diameter in depth. The anterior flagellar pore opens at the proximal junction of
the girdle and suleus, the posterior pore at about 0.3 of the distance between the distal junction
and the antapex.

The nucleus is a spheroidal body, found in the center of the organism. Its axis is about 0.43
transdiameter in length. The cytoplasm is granular and is arranged in radial strands, sur-
rounding oblong vacuoles which extend from near the nucleus to the periphery. In surface view
these vacuoles give the organism a coarsely vacuolate appearance, with alveoli varying in size.
The surface is. striate, with fine, longitudinal lines, placed closely together and equal in number
on both epicone and hypocone, and about fifty across the ventral face. :

Dimenstons.—Length, 86”; transdiameter, 19; dorsoventral diameter, 59;
axis of nucleus, 27+.

OccuRRENCE.—A single individual was taken June 23, 1904, 13 miles off La
Jolla, California, with a No. 20 silk net, in a haul from 265 meters to the surface.

CoMPARISONS.—This is the most symmetrically rotund species in the sub-
genus Pachydinium. It lacks entirely the mammillated surface and any outer
alveolar layer, characteristic of that subgenus and, in consequence, might be
included in Lineadinium with other striate species. It has, however, the
rotundity of species of the former subgenus, combined with the marked radial
arrangement of the internal metaplasmic structures, so generally developed in
Pachydinium. It is the most finely striate species in the genus Gymnodinium.

Gymnodinium ravenescens sp. nov.
Plate 1, figure 10; text figure X, 21

DragNnosis.—This is a small species with ellipsoidal body, its length 1.47
transdiameters; girdle premedian, displaced three times its own width; sulcus
extending from apex to antapex; olive ochre chromatophores. Length, 93.
Pacific off La Jolla, California, August.

DEsScRIPTION.—The body is symmetrically ellipsoidal with broad, rounded apices, its length
1.47 transdiameters at the widest part. A cross-section of the body is nearly cireular with a
slight indentation on the midventral surface. The length of the hypocone is greater than that
of the epicone by 0.27. The transdiameters of both are subequal. The epicone is hemispherical
anteriorly, the sides slightly elongated posteriorly. The apex is broad and rounded. It has a
length on the left and right sides of 0.31 and 0.49 respectively of the total length of the body.

248 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The posterior half of the hypocone is a smoothly rounded hemisphere. The sides of the anterior
half are subparallel.

The girdle is premedian in position, its proximal end meeting the suleus at a distance from
the apex of 0.31 and its distal end 0.49 respectively of the total length of the body. Its course
around the body is that of a descending left spiral with the distal end displaced posteriorly
about three times its own width. The furrow is wide, about 0.08 transdiameter, and is deeply
impressed, its sides gradually curving outward to meet the surface of the body. The distal end
of the furrow is somewhat narrower than the proximal. The suleus begins near the apex and
extends to the antapex in a slightly sinuous course. The trough is relatively shallow and fades
out near both apices. Posterior to the proximal junction with the girdle the furrow becomes
narrow and again below the distal junction it contracts to about half the width anteriorly.
Beyond the posterior pore it widens and deepens, but soon fades out without reaching the
antapex. The anterior flagellar pore is found at the anterior junction of girdle and sulcus, the
posterior pore midway between the distal junction and the antapex.

The nucleus is an ellipsoidal body, closely filled with fine, moniliform, chromatin strands.
These follow its long axis which lies parallel with the major axis of the body. It lies in the left
side of the hypocone, quite close to the surface. The major and minor axes of the nucleus are
0.58 and 0.41 transdiameters in length respectively.

A small sacklike pusule opens into each flagellar pore. The cytoplasm is very clear and
transparent, its very finely granular structure seareely evident. Minute green spherules, oil
droplets, and a few refractive granules are scattered through it. A single large vacuole, clear
grey in color, was found on the right side near the junction of girdle and suleus. This was
slightly irregular in outline and had the appearance of a food body. Another smaller body of
the same color was present in the epicone. The cytoplasm is pearl grey in tone. The general
color of the organism is given to it by the small, fiat, ellipsoidal chromatophores scattered
profusely through the cytoplasm. These are olive ochre in color and are found near the center
of the cytoplasm as well as near the periphery.

Dimenstons.—Length, 53; transdiameter, 36; axes of nucleus, 21” and 15r.

OccuRRENCE.—A single individual was taken August 6, 1917, with a No. 25
net, 4 miles off La Jolla, California, in a haul from 60 meters to the surface in
a surface temperature of 21°2 C.

CoMPARISONS.—This is one of the few pelagic species of Gymnodinium
which shows the presence of distinct chromatophores. The other pelagic species
with chromatophores found by us include G. cinctum and G. herbaceum. Chro-
matophores are a quite common characteristic of the minute forms inhabiting
the sand beach, such as G. agile, G. flavum, and most species of Amphidinium,
and are also general among the fresh-water species. It is near G. fuscum in
proportions, but is more rotund posteriorly, smaller and more olivaceus. It
approaches Gyrodinium ovoideum in form of girdle.

Gymnodinium rete Schiitt
Text figure BB, 16
Gymnodinium rete Sehiitt (1895), p. 43, pl. 26, fig. 89.

DescripTtion.—Under this name Schiitt (1895) figures an organism with an elongated,
cylindrical body; girdle on the left side of the body only, with a groove extending anteriorly
from its proximal end; nucleus spheroidal, filled with chromatin granules; yellow ochre chromato-
phores; broad pseudopodium-like flagellum (?) extending from the girdle at the left lateral
margin of the body.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 249

This is a problematical organism and one which it is difficult to locate
systematically with the existing data. It presents no Gymnodinium charac-
teristics unless we consider it a mutilated form. The extension on the girdle
over half the ventral face would point towards Hemidinium for its affinities,
rather than towards Gymnodinium. Until it has been redescribed, however, it
must be left among the species incertae sedis. Its condition indicates approach-
ing cytolysis, and its structure suggests that its anteroposterior orientation has
been reversed.

Gymnodinium rhomboides Schiitt
Text figure Y, 15

Gymnodinium rhomboides Schiitt (1895), p. 163, pl. 21, fig. 63.

G. rhomboides, Lemmermann (1899), p. 358.

G. rhomboides, Paulsen (1907), p. 23; (1908), pp. 97, 99, fig. 136. After Schiitt (1895).

G. rhomboides, Doflein (1909), p. 461, fig. 412,..; (1911), p. 527, fig. 472, ,. After Schiitt
(1895).

G. rhomboides, Lebour (1917b), pp. 183, 190, 191, fig. 6. In part, includes G. fisswm.

Dracnosis.—A small species with symmetrical biconical body, its length 1.76
transdiameters; girdle displaced twice its own width; sulcus extending from
near the apex to a short distance from the antapex; surface ridged. Length,
46v. Atlantic or Mediterranean at Naples, Skagerak, and Plymouth Sound,
England.

DescripTiIon.—The body is biconical or rhomboidal in shape, widest at the middle, its length
1.7 transdiameters. The epicone and hypocone are both symmetrically cone-shaped (about 60° )
with rounded apices. The hypocone exceeds the epicone in length by about 0.13 of its own length.
The epicone has a length on the left and right sides of the sulcus of 0.47 and 0.57 respectively
of the total length of the body.

The girdle joins the suleus proximally about 0.47 and distally 0.57 of the total length of the
body from the apex. It is slightly premedian in position as a whole. It has a width of about
0.09 transdiameter and is deeply impressed with overhanging borders. The suleus invades the
epicone slightly more than midway between girdle and apex and extends posteriorly to a short
distance from the antapex as a slightly sinuous line. The anterior flagellar pore is found at the
proximal junction of the girdle and suleus and the posterior pore near the distal end of the
suleus.

The nucleus is a small spheroidal body, centrally located. Its diameter is about 0.4 trans-
diameter in length. The cytoplasm is filled with minute spherules of various sizes, most numerous
in the epicone and near the antapex. The surface is ribbed with faint longitudinal furrows (7),
about fifteen across the dorsal face, which are distinct near the girdle and fade out near the
apices.

¢

Dimenstons.—Leneth, 46”; transdiameter, 26; diameter of nucleus, 12s.

OccuRRENCE.—This species was figured by Schtitt (1895) from the collee-
tions of the Plankton Expedition from the Bay of Naples or from the Atlantic.
Tt has been recorded from the Skagerak by Paulsen (1907) and from Plymouth
Sound, England, by Lebour (1917D).

250 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Comparisons.—The marked biconical symmetry of the epicone and hypocone,
combined with the striate surface, distinguish this species, at once, from all
others in the genus. It has somewhat the same size and proportions as G.
scopulosum sp. nov. (fig. X, 6), but is less rotund and has striae, or at least
linear markings, due to modifications on or in the surface layer of cytoplasm.

Gymnodinium roseolum (Schmarda) Stein
Text figure BB, 11

Glenodinium roseolum Schmarda (1854), p. 12, pl. 1, fig. 9.

G. roseolum, Leuckart (1861), p. 256. Based on Schmarda (1854).

G. roseolum, Diesing (1866), p. 105.

G. roseolum, Stein (1878), p. 73, as Gymnodinium roseolum, p. 90.

Gymnodinium roseolum, Eyferth (1879), p. 19.

Peridinium roseolum, Maggi (1880a) ; Glenodinium roseolum (1880b), p. 12.

Gymnodinium roseolum, Saville-Kent (1880-82), p. 444, pl. 25, fig. 53. Based on
Schmarda (1854).

Glenodinium roseolum, Biitschli (1885), pp. 965, 1018.

G. roseolum, Entz (1888) ), p. 41; as Gymnodinium roseolum, (1902), p. 124; (1907), p.
17 = (1909), p: 253:

Gymnodinium roseolum, Schilling (1891b), pp. 199, 206. Lapsus.

Glenodinium roseolum, Schewiakoff (1893), p. 157.

G. roseolum, Lemmermann (1900), p. 118.

Dracnosis.—A minute species with ovoidal body, its length 1.28 transdiam-
eters: girdle premedian; color pale pink. Fresh water in Egypt, February.

Description.—The body is ovoidal, widest near the middle, its length 1.28 transdiameters at
the widest part. The epicone is about 0.5 the length of the hypocone and 0.68 its greatest width,
with rounded outline. The hypocone is rounded anteriorly, subconical (about 63°) posteriorly,
with blunt apex.

The girdle is premedian in position, its distance from the apex being about 0.3 the total
length of the body. It is narrow and deeply impressed. The suleus, flagella and nucleus were
not observed by Sechmarda (1854), the only cell inclusions being one red and several green
spherules (chlamydomonads). The general color is pale pink. It is apparently holozoic in
nutrition.

Dimensions.—Length, 384; transdiameter, 29.5.

OccuRRENCE.—It was figured by Schmarda (1854) from the Natron Sea in
Egypt in February.

Comparisons.—Schmarda’s description is rather inadequate. but since the
form figured is quite unlike any other species of Gymnodinium it seems best
to let it stand until further work shall complete the description. Its shape,
proportions, and size are near those of G. cinctum sp. nov. (fig. X, 28), a marine
species, but its color differs, being pink instead of ochraceous. The color is
unusual in fresh-water species.

SynonymMy.—It was figured by Schmarda (1854) as Glenodinium roseolum,
but it was later changed by Stein (1878) to Gymnodinium.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA

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Gymnodinium rotundatum Klebs
Text figure X, 8

Gymnodinium rotundatum Klebs (1912), pp. 392, 403, 439, fig. 5.
G. rotundatum, Cavers (1913), p. 182, fig. 9,_..
G. rotundatum, Schilling (1913), p. 16, fig. 13.

Dracnosis.—A small species with rounded subellipsoidal body, its length 1.1
transdiameters; girdle without displacement; sulcus extending from girdle to
antapex; yellow chromatophores. Length, 34". Fresh-water swamps near
Vernheim, Germany.

Descrietion.—The body is stout ellipsoidal, its length 1.1 transdiameters at the widest part.
The epicone and hypocone are subequal in length. The epicone is hemispherical in shape, the
left side more convex than the right. Its length is about 0.5 the total length of the body. The
hypocone is broadly rounded with the antapex obliquely concave on the left side.

The girdle is submedian in position and forms a complete circle about the body. Its distance
from the apex is about 0.5 of the total length of the body. The furrow is wide, about 0.1 trans-
diameter, and deeply impressed. The sulcus extends from the girdle to the antapex as a wide
furrow. The position of the flagellar pores is not indicated in Klebs’s (1912) figures.

The nucleus is a small spherical body in the central part of the organism. Its diameter is
about 0.29 transdiameter in length. Numerous yellow rod-shaped chromatophores are radially
arranged in the peripheral zone of the cytoplasm.

Dimenstons.—Length, 32-35; transdiameter, 22-25; diameter of nucleus,
4, In Klebs’s (1912, fig. 5c) figure, however, the dimensions are 34” by 30+,
and we have followed this in the figure and description given herewith, rather
than distort his figure to conform to the dimensions given in his text.

OccuRRENCE.—This species has been described by Klebs (1912) from fresh-
water swamps near Vernheim (Reid, Hessen), Germany, and has not been noted
elsewhere.

ComPARISONS.—This species is near G. uberrimum in proportions, but is
somewhat more rotund anteriorly and less symmetrical posteriorly. Its chro-
matophores resemble those of G. mirabile and G. wherrimum in being rodlike
and radially arranged. It is also near G. bogoriense of the same author (Klebs,
1912), from Java, but the latter is smaller and more regular in outline.

Gymnodinium rubricauda sp. noy.

Plate 8, figure 88; text figure X, 4

Dracnosis.—A medium sized species with subovoidal body, its length 1.25
transdiameters; girdle submedian, without displacement; sulcus extending
from apex to antapex; color, rose red. Length, 69». Pacifie off La Jolla,
California, July, August.

Descrrerion.—The body is subovoidal, widest posteriorly, tapering anteriorly, its length 1.25
transdiameters at the widest part. In cross-section the body is nearly circular with a deep

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

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trough down the ventral face. The lengths of the epicone and hypocone are about equal, but
the hypocone, having a continuously wider transdiameter, exceeds the epicone in size. The
epicone has the shape of a cone of about 70° with a blunt, rounded apex. The sides form almost
straight lines from the apex to the girdle. The middle third of the ventral face is deeply concave,
forming a trough in the bottom of which lies the suleus. This becomes shallow anteriorly, fading
out at the apex. The length of the epicone is about 0.49 of the total length of the body. The
hypocone is truneate-pyramidal in outline and is less symmetrical than the epicone. The sides
are concave-convex and form angles of about 25° with the longitudinal plane of the body. The
antapex is broad, about half the greatest diameter of the body, and is truncated by the broad
suleal notch.

The girdle is submedian in position, its distance from the apex being 0.49 of the total length
of the body. It forms a complete circle about the body, the ends meeting without displacement.
The furrow has a width of about 0.08 transdiameter and is deeply impressed. The anterior lip
is deeply undereut, the posterior side of the furrow gradually rounding out to the surface of
the body. The borders of the girdle are smooth.

The suleus extends from the apex to the antapex in a slightly sigmoid curve. It lies at the
bottom of a broad trough which indents the ventral face of the body. It is narrow, expanding
beyond the posterior flagellar pore both laterally and in depth, forming a broad notch at the
antapex. The anterior flagellar pore opens at the junction of the girdle and suleus. The
transverse flagellum traverses 0.95 of the entire length of the girdle. The posterior flagellar
pore is found slightly beyond the midpoint between the girdle and the antapex.

The nucleus is a large, spheroidal body filled with moniliform chromatin strands. It is found
on the left side of the body slightly anterior to the equatorial plane. Its axis is about 0.47
transdiameter in length.

The cytoplasm is very finely granular, clear and transparent. Sacklike pusules are usually
present at either or both pores. Nutrition is holozoic, indicated by the presence of food bodies
in the cytoplasm. In the individual figured two food bodies were present. One was a large
grey-green, spheroidal body on the right side near the nucleus, the other was an irregular mass
in the posterior part of the body, mustard yellow in color. The general color of the organism
is rose red diffused through the cytoplasm. This is strongest in the epicone and near the
periphery, with more neutral pearl-grey tone in the hypocone. In the antapical region the
coloring matter or pigment is condensed into a few, very small, rose-red granules. A group of
larger granules of the same color can be found in the apex. No striae or other surface markings
could be detected.

Dimenstons.—Leneth, 68-854; transdiameter, 54-694; axis of nucleus,
20-27.

OccURRENCE.—This was first met with July 18, 1917, in a haul taken with a
No. 25 silk net, 4 miles off La Jolla, California, from 80 meters to the surface
and in a surface temperature of 20°8 C. It was found in most of the hauls
taken hetween that date and August 21, both in the surface hauls at the end of
the pier at the Biological Station and in those made farther offshore. It was
most abundant towards the end of that time, sixteen individuals being counted
in the last haul examined.

CoMPaARISONS.—This species belongs to a color group which has represent-
atives also in Gyrodinium, Cochlodinium, Pouchetia, and Erythropsis, charac-
terized by various shades of red. This group is represented in Gymnodinium
by G. sulcatum, G. rubrum, and G. contractum, all of which show the same shade
of rose red. This is repeated also in Cochlodinium rosaceum. In Gyrodinium

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 253

the color shades from dahlia purple in G. postmaculatum to coral red in G.
corallinum. In Pouchetia the color in this group varies from amaranth purple
in P. purpurescens to dahlia purple in P. purpurata and spinel red in P. voracis.

Gymnodinium rubricauda belongs in the subgenus Gymnodinium, as do most
of the species with colored pigment in the genus. It belongs to the group, in
the subgenus Gymnodinium, which includes G. sulcatum and G. contractum,
in which the differences are mainly in proportions, distribution of the color,
and the extent of the sulcus. The sulcus extends from apex to antapex in G.
sulcatum and G. rubrum (figs. X,1; Y, 4), but is confined to the hypocone in G.
contractum (fig. X, 2). In addition to these peculiarities the surface of G.
rubricauda is entirely devoid of striae, while feeble markings occur on the
hypocone of G. sulcatum and on the epicone of G. contractum. In view of the
number of individuals conforming to these differences, seen in the case of G.
suleatum and G. rubricauda, we conclude that they are not phases of one and
the same species.

Gymnodinium rubrum sp. noy.
Plate 8, figure 86; text figures A, Y, 4

DraGnosis.—This is a large species with ovoidal body, its length 1.81 trans-
diameters; girdle submedian, descending left spiral, displaced 0.37 transdiam-
eter: sulcus extending from apex to antapex in a sinuous course; surface striate ;
color pale glaucous green and rose red; remarkably labile in form. Length, 145+.
Pacifie off La Jolla, California, July, August.

Description.—The body is quite labile and variable in shape, normally oyoidal, circular in
cross-section, widest anteriorly, with broad, rounded apices, its length 1.81 transdiameters at
the widest part. Individuals showing great metabolic changes and distortions are frequently
met with (fig. A). These variations include rounded-up forms and larger ones with deeply lobed
apical or antapical ends. The epicone and hypocone are subequal in length, but the usually
greater transdiameter of the epicone increases its relative size slightly. The epicone is rounded
to conical in shape with broad apex. It has a length on the left and right sides of 0.4 and 0.59
respectively of the total length of the body. The hypocone is more asymmetrical than the
epicone with greater irregularity in its outline. The antapex is broad and rounded and more
or less deeply notched by the distal end of the sulcus.

The girdle is submedian in position, its proximal end joining the suleus at a distance from
the apex of 0.4 and its distal end at 0.59 of the total length of the body. It follows a descending
left spiral course around the body with a posterior displacement of its distal end of 0.37 trans-
diameter and with an overhang of about 0.01 transdiameter. The furrow is wide, about 0.06
transdiameter, and deeply impressed, its overhanging borders raised considerably above the
surrounding surface of the body.

The suleus usually begins at or near the apex and extends posteriorly to the antapex. It
follows a slightly sinuous course on the epicone and is deflected sinistrally at an angle of about
20° below the anterior junction with the girdle. After passing the distal junction it again °
assumes a nearly longitudinal direction and continues thus to the antapex. Throughout its
course it occupies a deep trough which widens to twice its anterior transdiameter beyond the

254 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

proximal junction with the girdle, narrows somewhat at the distal junction and expands and
deepens near the posterior part of the body. The anterior flagellar pore is found at the proximal
junction of the girdle and sulcus and the posterior pore about 0.18 transdiameter below the
distal junction.

The nucleus is ellipsoidal and is found near the proximal end of the girdle on the left side
of the body. It is composed of two distinct regions: an inner region which is granular or may
exhibit moniliform chromatin strands, and surrounding this a zone which exhibits no differ-
entiating structure. This zone has a width of about 0.17 transdiameter and has a double-
contoured outer membrane. In one case it seemed to have the vacuolate structure similar to
that found in the nucleus of Gyrodinium corallinium (pl. 10, fig. 117). The major and minor
axes of the nucleus are 0.4 and 0.3 transdiameters in length respectively.

A sacklike pusule is usually present at the anterior flagellar pore. In some individuals it
was present at both pores. The cytoplasm is remarkably clear and transparent. Among all
the specimens observed very few possessed cell inclusions, such as food masses and oil globules.
Many were seen, however, with what appeared to be a food vent at the posterior end of the body,
as if a large food mass had been recently ejected. The color of the cytoplasm is pale diffused
rose red at the anterior end, shading posteriorly to pale sea-foam yellow or pale glaucous green.
These colors are strongest at the apices and appear to be diffused through the cytoplasm.
Minute granules of rose red pigment are usually present in the periphery of the body, strung
along the surface striae like beads on a string. These are most numerous at the apex and girdle,
the largest granules being found along the proximal border of the girdle. On the hypocone
they are scattering, few in number, and widely separated.

The surface is striate, with longitudinal, equidistant lines. The number of lines on the
epicone is about half that on the hypocone. They are clear greenish yellow, and may be
continuous or may be composed of short, broken dashes.

Dimenstons.—Length, 100-1454; transdiameter, 75-90“; axes of nucleus,
30-37 and 25-27.

OccURRENCE.—This species was found abundantly in most of the hauls made
between July 11 and August 22, 1917, and was present in surface hauls as well
as those made from 80 meters to the surface, and at distances offshore varying
from the end of the pier at the Biological Station at La Jolla, California, to
10 miles.

ComPpaRIsONS.—This species is unique in the genus Gymnodinium in pos-
sessing a nucleus composed of two distinct parts. This was found in all the
individuals observed and thus could not be a temporary condition characteristic
of some particular stage in the life history. Dividing forms, however, were
notably absent in all the material under observation. The same type of nucleus
is present in Gyrodinium corallinum and G. virgatum. Here, again, the ap-
pearance of the dividing nucleus was not observed.

It belongs to the subgenus Lineadinium, but the degree of displacement of
the girdle and torsion of the body bring it close to the genus Gyrodinium. The
similarity of its nucleus to that of certain species in that genus strengthen the
relationships. It is on the border line between the genera Gymnodinium and
Gyrodinium, and might be included in either without violence to its structural
revelations.

It is near Gymnodinium lineatum sp. noy. (fig. Y, 14), but differs in its
surface markings, form of hypotheca, and lability.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA

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Gymnodinium scopulosum sp. noy.

Plate 1, figure 7; text figure X, 6

DraGnosis.—A small species with obovoidal to subbiconical body, its length
1.8 transdiameters; girdle submedian in position, displaced 0.3 transdiameter ;
sulcus extends’ from near apex to antapex; color, oil yellow. Length, 47+.
Pacifie off La Jolla, California, August.

Description.—The body is obovoidal, widest anteriorly, tapering slightly at both apices
which are rather broad, its length 1.8 transdiameters at the widest part. The epicone exceeds
the hypocone in length by 0.11 of its own length, and in transdiameter by 0.21 of its own trans-
diameter. It forms an overhanging, craglike dome with rounded sides and slightly tapering
apex. It has a length on the left and right sides of 0.4 and 0.56 respectively of the total length
of the body. The hypocone is more slender than the epicone, tapering more posteriorly with a
narrow antapex.

The girdle is submedian in position. Its proximal end joins the sulcus at a distance from
the apex of 0.4 of the total length of the body. It passes around the body in a descending left
spiral course, its distal end meeting the sulcus at a distance from the apex of 0.56 of the total
length of the body, displaced 0.3 transdiameter. The furrow has a width of about 0.09 trans-
diameter and is deeply impressed, undercutting the anterior border and smoothly curving out
to the posterior one. The anterior border projects far out beyond the posterior border. The
suleus begins a short distance below the apex and extends posteriorly in an almost straight line
to the antapex. The anterior flagellar pore opens at the proximal junction of the girdle and
sulcus, the posterior pore midway between the distal junction and the antapex.

The nucleus is a small ellipsoidal body lying in the left side of the epicone. It is filled with
coarse, moniliform chromatin strands following its longest diameter. Its major and minor axes
are 0.53 and 0.36 transdiameters in length respectively.

A small sacklike pusule opens into each flagellar pore. The cytoplasm is very finely granular
and contains few inclusions, such as vacuoles and food bodies. Near the posterior end of the
nucleus one large pink vacuole and a number of small, blue-green ones were present in the
epicone. The color of the cytoplasm presents a mixture of blue green, oil yellow, and pearl
grey, with deeper tones of oil yellow on the sides and at both ends. A thin, hyaline cyst,
considerably larger than the body, enclosed the organism.

Driuenstons.—Length, 47“; transdiameter, 26+; axes of nucleus, 14» and 9;
length of cyst, 524; transdiameter of cyst, 38v.

OccuRRENCE.—T'wo individuals were taken August 6, 1917, in a haul 4
miles off La Jolla, California, from 60 meters to the surface and in a surface
temperature of 21°2 C.

Comparisons.—This species belongs to the subgenus Gymnodinium sensu
strictu, characterized by a thin periplast without surface markings. It is close
to G. lunula, but is larger, has more tapering apices, greater disproportion of
epicone and hypocone, and straighter suleus. Nothing is known of “‘pyrocystis”’
stages of this species.

256 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Gymnodinium simplex (Lohmann) Kofoid and Swezy
Text figure BB, 8

Protodinium simplex Lohmann (1908), pp. 264, 265, pl. 17, fig. 17; (1911), pp. 23, 30, 31,
fig. 12.

P. simplex, Schiller (1911), p. 31.

P. simplex, Ostenfeld (1913), p. 339.

DracNosts.—This is a minute species with broadly ellipsoidal body, its length
1.53 transdiameters; girdle median, a closed circle; sulcus absent (?) ; yellow,
leaflike chromatophores. Length, 20u. Baltic Sea near Kiel, Germany, through-
out the year.

DescriptioON.—The body is broadly ellipsoidal with broad apices, circular in cross-section, its
length 1.53 transdiameters at the widest part. The girdle is poorly defined in Lohmann’s figure
(our text figure BB, 8), but seems to be median in position, dividing the body into two subequal
parts, both subhemispherical in shape, with broad, rounded apices. His figure further lacks
flagella and pores as well as any indication of a suleus. The latter structures he notes as absent.

The nucleus is a relatively large body centrally located and filled with chromatin granules.
Its diameter is about 0.6 transdiameter of the body in length. Yellow, leaflike chromatophores
are arranged in the periphery of the cell. These vary from four to many in number.

Dimenstons.—Length, 10-20-; transdiameter, 13; diameter of nucleus, 8.

OccurRRENCE.—Described by Lohmann (1908) from the Baltic Sea near Kiel,
Germany, where it occurred throughout the year, sparingly in the winter and
reaching its maximum in July.

SynonymMy.—This species was described by Lohmann as Protodinium
simplex, thus creating for it a new genus without, however, a full statement of
his reasons for so doing. The lack of a definite sulcus cannot well be used as
a generic distinction, since this structure, as well as the girdle, is sometimes
lacking in Lohmann’s figures of other species, as well as in those of many
earlier biologists. It possesses only the characters of the girdle, hypocone, and
epicone, which identify it with the group of minute Gymnodiniwm, and we there-
fore place it in that genus, discarding Lohmann’s new genus, Protodinium,
pending a full reéxamination of these details. In the event that there is no
trace of the sulcus prior to cytolysis, the genus Protodinium might well stand
and be transferred to the Protodiniferidae. Our reluctance to place it there
now is based on our experience with living, naked dinoflagellates in crowded
plankton collections, such as those with which Lohmann evidently worked. The
rounding up of the body under these conditions tends to obliterate the girdle
and suleus, and this may have been the case with the individuals on which
Lohmann’s figures and description are based.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 257

Gymnodinium situla sp. noy.
Plate 1, figure 12; text figure Z, 6

Dracnosis.—This is a medium sized species with rotund, cup-shaped body
with conical epicone; its length 1.2 transdiameters; girdle submedian, displaced
its own width; suleus extending from apex to antapex; surface finely striate;
color, pale dull green yellow. Length, 66. Pacific off La Jolla, California,
July, August.

DescripTIOn.—The body is rotund, shaped somewhat like a cup with a high conical cover,
widest in the girdle region, its length 1.2 transdiameters at the widest part. In cross-section
the body is nearly circular with only a slight groove down the midventral surface. The hypocone
exceeds the epicone in size, its length being subequal, but its wider transdiameter giving it a
greater actual size. The epicone has the shape of a short cone of about 90°, with a broad base.
The apex is blunt and the sides only slightly convex. It has a length of about 0.45 on the left
and 0.50 of the total length on the right side. The hypocone is cup-shaped with a wide, flaring
border at the girdle. The sides taper very slightly towards the posterior end which is broad and
rounded, with the central part slightly notched by the distal end of the sulcus.

The girdle is submedian. Its proximal end joins the suleus at a distance from the apex of
about 0.45 and its distal end 0.50 of the total length of the body. It passes around the body in
a nearly transverse direction with a slight deflection posteriorly on the right side, which displaces
the distal end about one width of the girdle. The furrow is wide, about 0.09 transdiameter, and
is deeply impressed. The lip on the proximal side is undereut, the distal side of the furrow
gradually curving outward to the surface of the body. The borders are irregular in outline,
following the slight undulations of the surface. The sulcus begins at the apex and extends
posteriorly to the antapex. It occupies a narrow, deep trough which fades out at the apex.
Beyond the posterior flagellar pore it becomes wider and deeper, extending through the body
to the dorsal surface at the antapex, forming an excavation which deeply notches that part of
the body. The borders of the suleus are smooth in outline. The anterior flagellar pore is found
at the proximal junction of the girdle and suleus, the posterior pore midway between the distal
junction and the antapex.

The nucleus is spheroidal and is found in the right side of the posterior half of the body.
Its axis is about 0.3 transdiameter in length. A large sacklike pusule opens into the anterior
flagellar pore, a more slender one into the posterior pore.

The cytoplasm is granular and finely alveolate in structure. This is omitted from the figures
for the sake of clearness. A mass of large pink vacuoles occupies the major part of the epicone.
A smaller group of pink vacuoles, very much smaller in size, is found near the antapex. Two
large, spherical, ochraceous orange-colored bodies or vacuoles and one bluish one were located
near the anterior pore. These were presumably food bodies in digestion. Behind these and
closely grouped around the anterior pusule and on the right side of the sulcus was a mass of
small, highly refractive bodies. These were citron yellow in color, and were evidently of a fatty
nature. Nutrition is holozoie.

The entire surface of the organism is covered with fine, longitudinal, equidistant striae.
These were composed of short blue-green dashes, linearly arranged. The number on the hypocone
is about a fourth greater than on the epicone. There are about 30 striae at the girdle on the
epicone. The surface of the body is roughened and irregular, presenting a similar outline to
that shown in G. pachydermatum. In this form, however, the peripheral, alveolar zone of
ectoplasm is not so clearly differentiated as in the other species. The general color of the
organism is a pale, dull greenish yellow, shading to chalcedony yellow near the girdle and suleus,
the thickness of the body giving to the whole a rich effect.

258 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Dimenstons.—Lenegth, 66; transdiameter, 55; axes of nucleus, 19” and 15r.

OcCURRENCE.—One individual was taken July 26, 1917, with a No. 25 silk
net, 2.5 miles off La Jolla, California, in a haul from 80 meters to the surface
and in a surface temperature of 21:6 C. Another was taken August 17, with
the same apparatus and from the same depth, 0.75 mile off La Jolla, and on
August 21, in a haul 5 miles offshore and from 83 meters to the surface.

CoMPARISONS.—This species belongs in the subgenus Pachydinium along
with G. dogieli sp. noy., G. amphora sp. nov. (figs. AA, 6, 8), and other species
characterized by a thickened periplast. There is less structural differentiation
in that region in this species than in the remainder of the group. The slight
undulations of the surface, particularly noticeable along the borders of the
girdle, leave little doubt about the character of the layer of protoplasm imme-
diately beneath, hence its inclusion with that subgenus. In the richness of its
coloring and the cytoplasmic inclusions it resembles the larger species of that
subgenus, notably G. amphora and G. dogieli, being unlike them, however, in
having surface striae.

Gymnodinium sphaericum Calkins
Plate 4, figure 42; text figure AA, 9
Gymnodinium gracile var. sphacrica Calkins (1902), p. 429, fig. 20.

DiaGnosis.—This is a medium sized species with rotund, spheroidal body,
very slightly flattened dorsoventrally, its length and transdiameter nearly equal
or the length may be about 1.27 transdiameters; girdle premedian, displaced its
own width or slightly more; sulcus short on the epicone, extending to antapex;
color, amber yellow and olive ochre. Length, 60«. Atlantic off Woods Hole,
Massachusetts, and Pacific off La Jolla, California, July, August.

DescriPTION.—This is a medium to small species of robust habit, the body spheroidal to
broadly ellipsoidal, with broad apices, its length and width almost equal or its length may reach
1.27 transdiameters. In cross-section the body shows a slight dorsoventral flattening. This,
however, seems to be an unusual condition. The hypocone exceeds the epicone in size, its length
being greater by 0.3. The epicone has an outline of something less than a hemisphere, with
broad, smoothly rounded apex. It has a length on the left and right sides of 0.28 and 0.38
respectively of the total length of the body. The posterior half of the hypocone is hemispherical
in shape, the sides of the anterior half being subparallel. The apex is broad and rounded. In
figure 42, plate 4, the body is slightly distorted in outline as though from the result of pressure
obliquely on the surface. Text figure AA, 9, gives a better outline of the normal individual.

The girdle is premedian in position, its distance from the apex at the proximal end being
about 0.28 and at its distal end 0.38 of the total length of the body. Its path around the body
is that of a descending left spiral, displaced posteriorly its own width or slightly more. The
furrow is wide, about 0.06 transdiameter, and is deeply impressed. The anterior lip is under-
cut, the posterior side of the furrow gradually rounding out to the surface of the body. The
borders of the girdle are marked by the undulations of the surface of the body or they may be
smooth. The suleus may invade the epicone only a short distance or may reach nearly to the
apex. The anterior flagellar pore is located at the proximal junction of the girdle and sulcus,
the posterior pore a short distance below.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 259

The nucleus is an ellipsoidal body filled with coarse, moniliform chromatin strands. It is
found in the anterior half of the body. Its major and minor axes are about 0.49 and 0.29
transdiameters in length respectively. The greatly elongated nucleus in figure 42, plate 4, is a
predivision stage.

Small, sacklike pusules may open into either or both flagellar pores. The cytoplasm is very
finely granular, clear and transparent. The body usually contains numerous food masses and
small refractive granules. The presence of long, slender green rodlets is common in many
individuals. In text figure AA, 9, the posterior part of the body is filled with a very large food
body. Nutrition is holozoic. A distinct eetoplasm can be observed in most of the specimens.
This is most conspicuous on the surface which exhibits the same undulations found in G.
pachydermatum. The general color of the organism is pale cendre green shading to yellow
ochre. No striae or other markings could be detected on the surface.

Druensions.—Lenegth, 47+ to 68; transdiameter, 401 to 47; axes of nucleus,
10v and 10+.

OccURRENCE.—This was figured by Calkins (1902) from the Atlantic off
Woods Hole, Massachusetts, July, August. It was first seen in the Pacific at
La Jolla, California, July 18, 1906, in a surface haul made with a No. 20 net.
On July 20 it was again taken under the same conditions. During July and
August, 1917, it was frequently met in the surface hauls made at the end of the
pier at the Biological Station and in a number of the deep hauls made farther
offshore. The number of individuals observed in one haul varied from one to
three. A thin, double-contoured cyst enclosed many of them when first observed.
Tn one specimen noted two individuals were enclosed in one cyst, probably the
resulting products of division.

Compartsons.—This species belongs in the subgenus Pachydinium because
of the presence of a thickened ectoplasm. Its color, greenish yellow, is that
common to many of the species in that subgenus. It does not, however, show
the highly differentiated ectoplasmic structure found in G. pachydermatum
sp. noy. (fig. AA, 5), but more nearly approximates the condition in G. situla
sp. nov. (fig. Z, 6) and, perhaps, G. tenuissimum sp. noy. (fig. AA, 7). Its
smaller size and rotund ovoidal body clearly distinguish it from other species.

SynonyMy.—This species was figured by Calkins (1902) as G. gracile var.
sphaerica. It differs from G. gracile, however, in its lack of surface striae, size,
proportions, and in its type of ectoplasmic differentiation, and is thus specifically
distinct rather than subspecifically.

Gymnodinium sulcatum sp. noy.
Plate 8, figure 83; text figure X, 1

Dracnosis.—A medium sized species with broad, rotund ovoidal body, its
length 1.05 transdiameters; girdle submedian without displacement; sulcus ex-
tending from apex to antapex; hypocone sparsely ribbed; color, dull rose red.
Length, 634. Pacific off La Jolla, California, August.

Description.—The body is rotund, its length and transdiameter nearly equal, widest at the
middle, narrow anteriorly and broad posteriorly. In cross-section the body is nearly circular.
The epicone and hypocone are subequal in size. The epicone is subconical in shape with an
angle of about 80°. The sides are convex, the left one slightly sigmoid in outline, with scarcely

260 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

pointed apex. It has a length of 0.5 of the total length of the body. The hypocone is sub-
hemispherical in shape, broadly notched at the antapex by the distal end of the suleus. The
left side is slightly sigmoid in outline, the right side nearly straight. The posterior end is
bilobed in ventral view with two short, broadly rounded lobes.

The girdle is submedian and forms a complete circle around the body. Its distance from the
apex is about 0.5 of the total length of the body. The furrow is wide, about 0.08 transdiameter
and rather shallow, with smoothly rounded borders. The suleus begins at the apex and extends
posteriorly in a slightly sinuous line to the antapex. The furrow is narrow and lies in the
middle of a wide trough which indents the ventral surface of the body. Posterior to the posterior
pore it becomes wide and deep, reaching through the body to the dorsal surface, and forming a
deep excavation at the antapex. The anterior flagellar pore is found at the proximal junction
of the girdle and suleus, the posterior pore midway between the girdle and antapex.

The nucleus is a spheroidal body found on the left side of the epicone. It is filled with
moniliform chromatin granules. Its axis is about 0.33 transdiameter in length.

A large club-shaped pusule opens into each flagellar pore. The cytoplasm is very finely
granular, clear and transparent. A single large, green yellow food mass was present near the
nucleus. This was enclosed in a much larger food vacuole. The color of the organism is a dull
rose red diffused throughout the cytoplasm. Near the apices particles of the coloring pigment
were condensed into small globules of bright rose red color. These were shghtly more numerous
at the antapex than at the apex. On the surface of the hypocone are a number of ridges begin-
ning below the girdle and extending posteriorly to near the antapex. These were four in
number on the ventral face and six on the dorsal. They are yellow in color, narrow and raised
slightly above the surface. None could be detected on the epicone. No other surface markings
were present.

Dimenstons.—Length, 63; transdiameter, 60; axis of nucleus, 20+.

OccuURRENCE.—A single individual was taken August 6, 1917, with a No. 25
silk net 4 miles off La Jolla, California, in a haul from 60 meters to the surface
and in a surface temperature of 21°9 C.

CoMPARISONS.—This species and G. contractum and G. rubricauda have
several features in common. The girdle forms a complete circle around the
body and the general color is the same. Ridges are present on the epicone in
G. contractum and are entirely absent in G. rubricauda. The enclosure of food
bodies in a conspicuous vacuole is common to both G. sulcatum and G. con-
tractum. The girdle is submedian in the three species. The possibility that
these three are varieties of one species cannot be overlooked. However, many
specimens of G. contractum and G. rubricauda were observed and these showed
no intergradations of form. The solitary individual of G. sulcatum makes that
species a more doubtful one.

Gymnodinium tenuissimum Lauterborn
Text figure AA, 7

Gymnodinium tenuissimum Lauterborn (1894), pp. 391, 396; (1898), p. 388, pl. 18, fig.
26; (1910a), p. 464; (19100), p. 499; (1913), p. 906.

G. tenuissimum, Lemmermann (1900), p. 116; (1902), p. 260; (1910), pp. 565, 618, 621,
fig. 21.

7. tenwissimum, Zschokke (1900), p. 43.

G. tenuissimum, Lang (1901), p. 25, fig. 41.

. tenuissimum, Schilling (1913), p. 18, fig. 17.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 261

Draanosis.—A medium sized species with dorsoventrally compressed, dis-
coidal body, its length 1.1 transdiameters; girdle without displacement; sulcus
short. Length, 60. Fresh-water ponds near Maudach, Germany, through the
winter months.

DeEscripTION.—A medium sized species with disklike body, flattened dorsoventrally to a thin
plate, its length 1.1 transdiameters. The hypocone exceeds the epicone in length by about 0.2 of
its own length. In ventral view the epicone is subhemispherical with the right side of the semi-
cirele longer than the left. Its length is about 0.4 of the total length of the body in the midyentral
region. The girdle curves posteriorly on the dorsal side, turning anteriorly before reaching the
midventral region, giving the right side of the epicone at the edge of the disk a length of 0.5 the
total length of the body. The hypocone is asymmetrical with a blunt antapex, longer upon the
right side.

The girdle, as well as the suleus, is incomplete in Lauterborn’s (1898) figures. Its distance
from the apex in the midventral region is about 0.4 of the total length of the body. It makes a
posterior sweep on the dorsal side of the body, turning anteriorly in the last quarter of its course
to the neighborhood of its origin. The furrow is rather deeply impressed, about 0.07 trans-
diameter in width, with sharply marked borders. The sulcus is only faintly indicated by a
short line on the hypocone. The transverse and longitudinal flagella apparently take origin at
points not far distant from the junction of the girdle and sulcus.

The nucleus is ellipsoidal and located in the central region of the body. It is filled with
coarse chromatin granules. Its major and minor axes are 0.3 and 0.2 transdiameters in length
respectively. The cytoplasm is filled with spherules of various sizes, and rounded, yellow-brown
chromatophores.

Dimensions.—Leneth, 66; transdiameter, 60“; axes of nucleus, 19” and 14+.

OccuRRENCE.—This was figured by Lauterborn (1894, 1899) from fresh-
water ponds near Maudach and Ludswigshafen, Germany, through the winter
months.

CoMPARISONS.—This species is tentatively allocated in the subgenus Pachy-
dinium beeause of its differentiated peripheral evtoplasm, marked by radial
structures. Lauterborn (1898) explicitly notes a clearly marked alveolar layer,
but does not give its location. There is no other species in the genus approaching
G. tenuissimum. The describer calls attention to its similarity to Glenodinium
foliaceum, a flattened thecate species of the Peridinioidea.

Gymnodinium tintinnicola Lohmann
Text figure BB, 13
Gymnodinium tintinnicola Lohmann (1908), pp. 259-260, 266, 366, pl. 17, fig. 6a-c.

The probability that some of the minute Gymnodinium found in the plankton
are swarm spores of parasitic species belonging, it may be, to other genera has
been demonstrated by Lohmann’s discovery of a minute species which he has
named G. tintinnicola. He found this organism emerging as a parasite from
Tintinnopsis nuclela, one of the lorica-forming ciliates of the marine plankton.
There were about ten of these ‘‘spores’’ in the ciliate. They have, in the free
state, the typical form of Gymnodinium with the two characteristic flagella, the

262 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

trailing longitudinal one and the ribbon-like transverse one, and travel in the
normal rotating fashion. There is apparently a sulcus and a postmarginal
suleal notch. No determination of the dinoflagellate nature of the nucleus was
made. The organism was colorless, about 18 in length and of nearly the same
width. ;

Somewhat similar ‘‘spores’’ with girdle and suleal notch were previously
deseribed by Lackmann (1906) as macrospores of Tintinnopsis campanula and
Cytharocytis helix. Lohmann (1908) justly criticizes this interpretation and,
correctly In our opinion, regards it as wholly improbable that a cilitate proto-
zoan would have a dinoflagellate macrospore. The spores figured by Lackmann
(1906, pl. 1, figs. 17-21) have a different appearance from those of Lohmann.
They are larger and taper more anteriorly.

Tt may well be that Brandt’s (1905) report that the swarm spores of the
Radiolaria are of the dinoflagellate type is based upon observations of parasitic
dinoflagellates and not radiolarian swarm spores. More evidence is essential
before this subject can be set forth in its correct relations. In the meantime
we leave Lohmann’s species tentatively in Gymnodinium. It will, in all proba-
bility, find its place ultimately among the Blastodiniidae or other parasitic
representatives of the dinoflagellates.

Gymnodinium translucens sp. noy.
Plate 2, figure 17; text figure Y, 2

DraGnosis.—A medium sized species with ellipsoidal body, its length 1.93
transdiameters; girdle submedian, displaced about twice its own width; suleus
extending from apex to antapex ; surface sparsely striate; color, bluish glaucous,
very hyaline. Length, 87. Pacific off La Jolla, California, June.

Description.—The body is slender ellipsoidal, pointed anteriorly, truncate posteriorly, its
length 1.93 transdiameters at the widest part. A cross-section of the body is nearly cireular
with the midventral surface slightly imdented. The epicone exceeds the hypocone in size, its
length being greater by 0:14. Its transdiameter is also shghtly larger. It is dome-shaped with
high rounded sides and a short, sharply pointed apex. It has a length on the left and right sides
of 0.51 and 0.60 respectively of the total length of the body. The sides of the hypocone are less
convex than those of the epicone. Posteriorly it is deeply emarginate by the suleal noteh, with
the two lobes broad and rounded.

The girdle is submedian in position. Its proximal end joins the suleus at a distance from
the apex of 0.51 and its distal end 0.60 of the total length of the body. The furrow is wide,
about 0.09 transdiameter, and deeply impressed, with the sides gradually curving out to the
surface of the body. The borders are marked by a double-contoured line, slightly crinkled and
blue green in color. The sulcus extends from the apex to the antapex in a slightly sinuous line.
It is very narrow and rather shallow on the epicone, expanding about three times this width
beyond the anterior flagellar pore. After passing the distal end of the girdle it becomes much
wider and sinks deeper into the body until, near the antapex, it reaches the dorsal surface,
bifurcating the posterior part of the body. The two lobes are broad and rounded. The anterior
flagellar pore opens at the proximal end of the girdle, near the place of union with the suleus.
The posterior pore is slightly beyond the distal junction of girdle and sulcus.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 263

The nucleus is a rather large, spheroidal body filled with fine chromatin strands. It is found
in the left dorsal side of the hypocone. Its axis is about 0.44 transdiameter in length.

The eytoplasm is very clear and transparent and without apparent granulations. It is
suffused throughout with a glassy, bluish glaucous tint which gives its color to the organism.
The anterior half of the body contains a large food mass, irregular ellipsoid in shape and greyish
javel green in color. Two smaller, grey, refractive bodies were present in the hypocone, and a
number of still smaller refractive bodies in the antapical region near the nucleus. Nutrition is
evidently holozoic. The surface is covered with longitudinal, equidistant striae, blue green in
color, about 20 across the ventral face of the girdle. The number of these on the hypocone
exceeds the number on the epicone by about 0.1.

Diwenstons.—Leneth, 87/; transdiameter, 45; axes of nucleus, 25.

OccurRENCcE.—A single individual was taken June 26, 1917, at La Jolla,
California, with a No. 12 net, 1 mile offshore, in a haul from 120 meters to the
surface and in a surface temperature of 20°6 C,

Comparisons.—This form has the glassy, glaucous appearance not uncom-
mon throughout the Gymnodiniidae, as, for example, in Cochlodinium vinctum
and Erythropsis extrudens. Gymnodinium gracile sometimes exhibits the same
bluish color, but the two species are widely different in their morphological
characters. It belongs to the subgenus Lineadinium, but stands rather alone.
Its epicone and general form approach that of G. multilineatum sp. nov. (fig.
Y, 18), but its bifid antapex, sparse striae and displaced girdle clearly separate
it from that species.

Gymnodinium triangularis Lebour
Text figure BB, 2
Gymnodinium triangularis Lebour (19176), p. 192, fig. 7.

The form figured by Lebour (1917D) as G. triangularis is evidently a muti-
lated specimen. The posterior part of the body is frequently deformed in many
of these frail, delicate organisms, as in Pouchetia maxima (pl. 6, fig. 61). This
is often the result of the extrusion of a large food mass, and the deformation
may last for some time or may close immediately. This process was often
followed by us, particularly in Gymnodinium heterostriatum.

The form figured by Lebour is subtriangular in shape, truncate posteriorly,
with the hypocone greatly exceeding the epicone in size. The sulcus is omitted
from the figure, but the longitudinal flagellum arises near the apex (?). The
data given are incomplete, and, combined with the reasons stated above, would
throw this among the doubtful forms until it has been found again. The point
of origin of what is apparently the longitudinal flagellum raises the question of
the orientation of this organism, which may possibly be inverted.

264 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Gymnodinium uberrimum (Allman) Kofoid and Swezy
Text figure X, 9

Poridinium uberrima, Allman (1854), pp. 118-120; (1855), pp. 24-25, pl. 3, figs. 9-17.

Melodinium uberrimum, Saville-Kent (1880-82), pp. 445-446, pl. 25, figs. 34-35.

Gymnodinium mirabile var. rufescens Penard (1891), pp. 34, 57, pl. 5, figs. 8-9.

G. mirabile rufescens, Imhof (1892), p. 175.

G. rufescens, Lemmermann (1900), p. 116; (1902), p. 260; (1910), p. 565, figs. 17, 18, pp.
623-624.

G. rufescens, Schilling (1913), p. 18.

Glenodinium uberrimum, Schilling (1913), p. 64.

Gymnodinium rufescens, West (1916), p. 53, fig. 38 A.

DraGnosis.—A small species with rotund body, its length 1.04 transdiame-
ters; girdle displaced its own width; sulcus short on epicone, extending to
antapex; vellow to brown chromatophores; red stigma; tendency to chain
formation. Length, 454. Dublin, Iveland; Lake Geneva, Switzerland.

Description.—The body is rotund biconical to ellipsoidal with rounded apices, its length
1.04 tranusdiameters at the widest part. The epicone and hypocone are subequal and both are
subeonical to subhemispherical in shape. The epicone has a length on the left and right sides
of about 0.54 and 0.63 respectively of the total length of the body in chain. The apex is broadly
rounded and the antapex is usually broadly notched.

The girdle is equatorial to slightly postmedian, its distance from the apex not exceeding 0.54
at its proximal junction and at its distal junction with the sulcus about 0.63 of the total length
of the body, with a displacement of not over its own width in chain, but generally with no dis-
placement at all. The furrow is wide, about 0.07 transdiameters, and quite deeply impressed.
The longitudinal flagellum arises slightly below the distal junction of the girdle and suleus.

The nucleus is spherical or ellipsoidal and filled with coarse beaded chromatin strands. The
cytoplasm contains numerous small spherules and elongated yellow chromatophores radially
arranged in the peripheral layer of the eytoplasm. A small spherical pusule is found at the
proximal junction of the girdle and suleus. A spheroidal red stigma is found in the posterior
end of the suleus.

DimeEnsions.—Length, 40-51, rarely 25; transdiameter, 38-42.

OccuRRENCE.—Originally reported by Allman (1854, 1855) in immense
numbers from deeply discolored pond water in Phoenix Park, Dublin, Ireland.
Later Penard (1891) found it in Lake Geneva, Switzerland. The references of
Imhof (1892), Lemmermann (1900, 1902, 1910), Schilling (1913), and West
(1916) are only citations.

CoMPARISONS.—Gymnodinium rufescens is one of the small group of this
genus, mostly fresh-water forms, having chromatophores and limited apparently
to a holophytie type of nutrition. It is most closely related, morphologically,
to G. mirabile, G. palustre, G. carinatum, and G. aeruginosum. It shows the
typical yellow or yellow ochre color characteristic of this group, and is the
stoutest, most nearly spherical member. It lacks the keel at the left of the
sulcus in G. carinatum and the girdle of G. mirabile.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 265

Synonymy.—Although very clearly described by Allman (1854, 1855) as
Peridinium uberrima, this species seems to have been neglected by subsequent
investigators and monographers, such as Lemmermann (1910) and Schilling
(1913), apparently because of the lack of access to the journals containing the
original description. Allman’s account of cyst formation, or the appearance
of a delicate spherical pellicle (no girdle noted), is probably the reason for
Schilling’s allocation of the species to Glenodinium. Saville-Kent (1880-82)
established, on inadequate grounds, a new genus Melodinium with Allman’s
Peridinium uberrima as the sole species, and still continued Allman’s original
error of stating that the whole body was covered with cilia, an observation based
either on a coating of bacteria or on the optical illusion arising from the vibratile
action of the transverse flagellum in a rapidly moving individual.

Penard (1891) includes this species as variety rufescens of his G. mirabile.
Lemmermann later advanced the variety to specific rank. Schilling (1913) in
his useful monograph of the fresh-water dinoflagellates fails to recognize the
similarity of Allman’s and Penard’s forms and apparently on the basis of All-
man’s observation of a pellicular cyst and of Saville-Kent’s suggestion that the
species may be a shell-less developmental condition of a thecate species, places
Allman’s uberrimum in Glenodinium among the ‘‘unsichere Peridineen.”’
There seems to be no ground for this transfer, as such cyst formation is a
normal feature of the life history of the naked dinoflagellates.

Gymnodinium varians Maskell
Text figure X, 23

Gymnodinium varians Maskell (1887), p. 7, pl. 1, fig. 9a-b.

G. varians, Schewiakoff (1893), p. 162.

¢. varians, Lemmermann (1900), p. 116; (1910), p. 565, figs. 19-20, pp. 618, 619, 621.
G. varians, Hutton (1904), p. 331.

G. minimum, Klebs (1912), pp. 396, 419, 439, fig. 7 A, B.

Diacnosts.—A minute species with ovoidal body, its length 1.3 transdiam-
eters: girdle median, without displacement; sulcus extending from girdle to
antapex; color, green. Length, 17. Wellington district of New Zealand;
Buitenzorg, Java.

Description.—The body is ovoidal with its widest transdiameter premedian, narrower pos-
teriorly, its length 1.5 transdiameters at the widest part. The epicone and hypocone are sub-
equal in length, but the epicone is slightly greater in volume. It has a length of 0.4 of the total
body length and is hemispherical in shape. The hypocone is somewhat more slender with blunt
antapex.

The girdle is subequatorial in position and forms a complete circle around the body. The
suleus extends from the girdle to the antapex in a straight line. The flagellar pores are not
indieated in Klebs’s (1912) figures, but the location of the flagella would suggest that the pores
might be found, one slightly below the other, at the junction of the girdle and sulcus.

The nucleus is spherical and centrally located. Its diameter is about 0.5 transdiameter in
length. The color is green. Chromatophores minute rod-shaped, radially located in the periphery.

266 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Dimenstons.—Length, 8-17“; transdiameter, 6-12; diameter of nucleus, 4.

OccuURRENCE.—Figured by Maskell (1887) from the Wellington district of
New Zealand. The only other occurrence recorded is by Klebs (1912) as G.
minimum from fresh water in the Botanical Gardens at Buitenzorg, Java.

SyNoNYMY.—Gymnodinium minimum, described by Klebs (1912) from
Buitenzorg, Java, is undoubtedly the same form described earlier by Maskell
(1887) from New Zealand.

Until the complete life history of the Dinoflagellata has been worked out in
-a sufficiently large number of species to allow of generalizations for the whole
group the exact allocation of many of the smallest forms described can be made
only tentatively. It is probable that some of these minute species, like G.
minimum, may prove to be only a stage in the development of some larger form.
Its small size places it near the bottom of the list in this respect in Gymnodinium,
if not, indeed, among all Dinoflagellata. Its rod-shaped green chromatophores
ally it to G. viride.

Gymnodinium vestifici Schiitt
Text figure Y, 10

Gymnodinium vestifict Schiitt (1895), pl. 25, fig. 85.

G. vestifici, Lemmermann (1899), p. 358.

G. vestifici, Lohmann (1908), pp. 252, 268, 368, table B; (1911), p. 31.
G. vestifict, Paulsen (1908), pp. 97, 98, fig. 134.

G. vestifict, Ostenfeld (1913), p. 388.

Dracnosts.—A small species with fusiform body, its length 3.13 transdiam-
eters; girdle anterior, displaced its own width; suleus short on both epicone and
hypocone ; surface striate on hypocone. Length, 47. Atlantic or Mediterranean
at Naples.

Description.—The body is fusiform, pointed at both ends, more tapering anteriorly, its
length 3.13 transdiameters at its widest part. The hypocone exceeds the epicone in length by
0.55 its own length. The epicone is short, with a length on the left and right sides of 0.25 and
0.34 respectively of the total length of the body. It is asymmetrically rounded anteriorly with
a pointed apex which is excentrically deflected dorsalward. The hypocone is slightly broader
than and over twice the length of the epicone, and in ventral view is less pointed with blunt
antapex.

The girdle is placed in the anterior third of the body, joining the suleus proximally about
0.25 and distally 0.34 of the total length of the body from the apex. It traverses a descending
left spiral course, displaced its own width. The furrow is wide, 0.28 transdiameter, and deeply
impressed. The sulcus is very short, extending but a short distance on either side of the girdle
in a narrow slightly smuous lne. The flagella and flagellar pores were not observed by Schiitt
(1895).

The nucleus is a small ellipsoidal body found in the region of the girdle. Its major and
minor axes are about 0.46 and 0.36 transdiameter in length respectively. It is filled with coarse,
chromatin granules. A few refractive rodlets are noted in the mid and anterior regions, and in
the peripheral layer many minute spherules are present. The surface of the hypocone is striate,
with longitudinal lines, but none are figured for the epicone.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 267

Dimensions.—Length, 47+; transdiameter, 15; nucleus, 6» by 5v.

OccURRENCE.—This species was figured by Schiitt (1895) from the collec-
tions of the Plankton Expedition from the Atlantic or from the Mediterranean
at Naples. It is also recorded by Lohmann (1908, 1911) from the Baltic Sea
off Kiel, Germany, where he found it throughout the vear, reaching its maximum
in August. Ostenfeld (1913) observed it in the Cattegat.

Comparisons.—Among striate species included in the subgenus Lineadiniwin
this species presents the maximum relative enlargement of the hypocone at the
expense of the epicone. A tendency in this direction is detected in G. aureum
sp. nov., G. achromaticum Lebour, G. attenuatum sp. nov., G. gracile Bergh,
G. abbreviatum sp. nov., and G. puniceum sp. nov. (figs. Y, 3, 8, 12; figs. Z, 3,
7,5). The limitation of striae to the hypocone is similar to that in G. herbaceum
Kofoid (fig. Y, 17). The species is a very aberrant one, widely divergent from
the others in the genus.

Gymnodinium violescens sp. nov.
Plate 6, figure 69; text figure X, 11

DraGNosis.—A small species with biconical body, its length 1.42 transdiam-
eters: girdle submedian, displaced about 3 times its own width; suleus extending
from girdle to antapex; color, pansy violet. Length, 604. Pacific off La Jolla,
California, July.

Description.—The body is asymmetrical, biconical, almost rhomboidal, with rounded apices,
its length 1.42 transdiameters at the widest part. Its dorsoventral and transdiameter are equal
in length. The epicone and hypocone are subequal in size. The epicone has the general shape
of a cone of about 80°, with broad, blunt apex. The left side of the base of the epicone is consid-
erably higher than the right, but the sides are equal in length, throwing the apex to the right of
the midplane of the body. The sides are slightly concave posteriorly and convex anteriorly.
The epicone has a length on the left and right sides of 0.43 and 0.58 respectively of the total
length of the body. The hypocone has the shape of a cone of about 65°, the left side of which is
about 0.02 longer than the right. Both sides have a greater convexity than those of the epicone.
The ventral surface is deeply grooved by the broad sulcus.

The girdle is submedian, its proximal end meeting the suleus at a distance from the apex of
0.43 and the distal end of 0.58 of the total length of the body. It forms a left-wound spiral, the
first half of the course taking a transverse or slightly anterior direction, the second half turning
posteriorly with its distal end displaced about 0.25 transdiameter. The furrow is wide, about
0.07 transdiameter, and deeply impressed. The anterior border is undercut by the furrow which
curves gradually outward to the posterior border. The borders are outlined by lines of bright
yellow green.

The suleus begins at the proximal end of the girdle and extends posteriorly to the antapex.
The trough is about equal to the girdle in width anteriorly. Beyond the junction with the distal
end of the girdle it becomes broader and deeper, the left side being deflected so widely that it
becomes lost near the lateral border of the body in ventral view. The right side is deflected to
a less extent, reaching a point nearer the antapex before fading out. The anterior flagellar pore
opens at the proximal end of the girdle, the posterior pore about two widths of the girdle behind
the distal end.

268 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The nucleus is a large, ellipsoidal body found near the central part of the cytoplasm. Its
long axis les in the short plane of the body. Its major and minor axes are about 0.66 and 0.39
transdiameters in length respectively.

The pusules were unusually large. The anterior one was spherical and thrown forward into
the epicone so that its outlet came at its posterior end. This reverses the usual position of this
organelle in the Gymnodiniidae. The posterior pusule was thrown to the right, the opening
being at the left side. It, also, was unique in that it had a slight purplish tinge. This may have
been due to the masses of that color around it. The cytoplasm is clear and very finely granular.
It contained no other cell inclusions except numerous small spherules of a bright yellow-green
color. The most striking feature of the whole organism is its colored pigment. The general
tone of the protoplasm is pearl blue, shading to light glaucous blue at the girdle and near the
periphery. Near the surface are numerous, small, rounded or disk-shaped bodies, pansy violet
near the apex, shading to amaranth purple near the antapex. These pigment masses are some-
what more numerous in the hypocone than in the epicone. No striations or other surface
markings could be detected.

Dimenstons.—Length, 60/; transdiameter, 42; axes of nucleus, 28” and 16+.

OccuRRENCE.—This species is represented by a single specimen taken July
26, 1917, with a No. 25 silk net, in a haul 2.5 miles off La Jolla, California, from
80 meters to the surface and in a surface temperature of 21°8 C.

Comparisons.—The color of this species finds its nearest counterpart in G.
puniceum. Different shades of the general color are represented by Pouchetia
purpurata and P. purpurescens. Like most of the species in this genus con-
taining colored pigment, it belongs in the subgenus Gymnodinium. Yn its rather
stout, biconical shape it is allied to the subgenus Lineadinium (fig. Y), which
is mainly composed of biconical species. G. violescens, however, lacks surface
striae. It is quite distinct in proportions and color from the other two biconical
species, G. filum Lebour (fig. X, 20) and G. fusus Schiitt (fig. X, 5) of the sub-
genus Gymnodinium.

Gymnodinium viride Penard
Text figure X, 24

Gymnodinium viride Penard (1891), pp. 11, 15, 22, 23, 33, 55, pl. 4, figs. 11-24.
viride, Imhof (1892), p. 175.

. viride, Lemmermann (1900), p. 116; (1902), p. 260; (1910), p. 613, fig. 26, p. 623.
. viride, West (1909), p. 189; (1916), p. 52, fig. 38a.

. viride, Klebs (1912), p. 440.

. viride, Forti (1913), p. 32.

. viride, Cunha (1913), p. 105.

. viride, Schilling (1913), pp. 19, 64.

Not Gymnodinium viride Schiitt (1895), pl. 26, fig. 88 (= Gyrodinium foliaceum).

ARAARAAR

D1AGNosis.—A small species with ellipsoidal body, flattened dorsoventrally,
its length 1.3 transdiameters; girdle displaced its own width; sulcus extending
from near the apex to near the antapex; green chromatophores. Length, 35,
Lake Geneva, Switzerland; Brazil.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 269

Description.—The body is ellipsoidal, widest at the middle and flattened dorsoventrally, its
length 1.3 transdiameters at the widest part. The dorsoventral diameter is about 0.7 of the
transdiameter. The epicone and hypocone are subequal in size with a tendency towards enlarge-
ment of the hypocone. The epicone is broadly rounded at the apex with a length on the left and
right sides of about 0.43 and 0.48 respectively of the total length of the body. The hypocone is
slightly wider anteriorly than the corresponding part of the epicone. The antapex is broadly
rounded or slightly truncate.

The girdle is submedian in position, its distance from the apex at the proximal and distal
ends being 0.43 and 0.48 respectively of the total length of the body. It is displaced posteriorly
slightly more than its own width. The furrow is narrow and deeply impressed with overhanging
borders. The suleus begins midway between the girdle and apex and extends posteriorly to the
antapex as a narrow, somewhat obscure trough.

The nucleus is a spheroidal body located in the central part of the epicone. Its axis is about
0.33 transdiameter in length. Numerous green, rod-shaped chromatophores are radially arranged
through the cytoplasm.

Dimensions.—Leneth, 35; transdiameter, 25; diameter of nucleus, 8.

OccurRENCE.—Figured by Penard (1891) from Lake Geneva, Switzerland.
Its occurrence has also been recorded by Cunha (1913) from Brazil.

CoMPARIsONS.—This species and G. carinatum, G. palustre, G. aeruginosum,

7. uberrimum, and G. mirabile form a group possessing the same general

morphological characters, namely, fresh-water forms with numerous chromato-
phores of green or yellow ochre color, and differing but little in general size
and proportions. Like Cunha’s (1913) record of G. fuscum, his finding of a
cool temperate water species which is common in Lake Geneva in the tropical
waters of Brazil raises the question of the specific identity of his organism with
G. fuscum. It is possible, however, that this, like a few other species of dino-
flagellates, such as Prorocentrum micans, is truly cosmopolitan in its range.

It is very close to G. aeruginosum in size and proportions, but differs in
having green instead of bluish green chromatophores and in their being rod-
shaped in form instead of elliptical disks.

Gymnodinium vorticella Stein
Text figure X, 29

Peridinium vorticella Stein (1878), pp. 73, 78.

Gymnodinium vorticella Stein (1878), p. 90; (1883), pl. 3, figs. 1-4.

G. vorticella, Eyferth (1879), p. 19.

G. verticella, Klebs (1883), p. 356; (1912), pp. 391, 429.

G. vorticella, Pouchet (1883), p. 402.

G. vorticella, Biitsehli (1885), pp. 986, 1017, pl. 51, fig. 7.

G. vorticella, Schilling (1891a), pp. 244, 276; (18916), pp. 200, 205, 206; (1913), p. 20,
fig. 19. Based on Stein’s (1878) figure.

G. vorticella, Dangeard (1892).

7. vorticella, Entz (1896), p. 22; (1902), p. 124; (1907), p. 17; (1909), pp. 258, 254;
(1910), pp. 162, 164.

7. vorticella, Ludwig (1898), p. 299.

7. vorticella, Mez (1898), p. 216.

270 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

G. vorticella, Schonichen and Kalberlah (1900), p. 231; (1909), p. 252.

G. vorticella, Lemmermann (1900), p. 116; (1902), p. 260; (1910), pp. 565, 625, fig. 23.
After Stein (1878).

(7. vorticella, Levander (1900), pp. 58, 64, 96; (1901), p. 6.

r. vorticella, Dogiel (1906), p. 32.

r. vorticella, Kiister (1908), p. 352.

G. vorticella, Kleiber (1911), p. 14.

G. vorticella, Lauterborn (1913), p. 868.

G. vorticella, West (1916), p. 53.

DraGcnosis.—A minute species, with ovoidal body, its length 1.1 transdiam-
eters; girdle displaced half its own width; suleus short on both epicone and
hypocone; colorless, holozoic. Length, 24H. In fresh-water ponds and swamps
in central Europe.

Description.—The body is broadly ovoidal, widest posteriorly, its length 1.1 transdiameters.
The epicone greatly exceeds the hypocone in size, its length being greater by 0.36 of its own
length. It is dome-shaped, with broad base and rounded apex. It has a length on the left and
right sides of about 0.52 and 0.58 respectively of the total length of the body. The hypocone has
a length on the left and right sides of 0.25 and 0.29 of the total length.

The girdle is postmedian in position, its junction with the suleus occurring at about 0.50 of
the total length of the body from the apex. The furrow is deeply impressed and about 0.14
transdiameters in width. The suleus is a shallow furrow reaching to near the antapex.

The nucleus is a small spheroidal body in the center of the epicone, having a diameter of
about 0.2 transdiameter of the body. Food masses are frequently found in the colorless cytoplasm
with few or many minute spherules. A red stigma is found in the posterior part of the sulcus.
Nutrition is holozoie.

DiMenstons.—Length, 23-244; transdiameter, 20-21”; diameter of nucleus,
4.5.

OccuRRENCE.—Figured by Stein (1883) from fresh water in the environs of
Prag. Entz (1896) notes its abundance in fresh water in Hungary.

CoMPARISONS.—This small colorless species is very close to Danysz’s G. muset
(fig. X, 3), but appears to differ from it in proportions, being more ovoidal and
lacking in the posterior sulcal notch, as well as having but a single eyespot
instead of two.

Gymnodinium wilezeki Pouchet
Text figure Z, 8

Gymnodinium wilczeki Pouchet (1894), pp. 170, 205, pl. 22, fig. 1.
G. wilezeki, Lemmermann (1901), p. 358.
G. wilczeki, Paulsen (1908), p. 108.

DraGcnosis.—A medium sized species with ovoidal, deeply constricted body,
its length 1.33 transdiameters; girdle without displacement; sulcus extending
from girdle to antapex; surface ridged; color, green. Length, 804. Arctic
Ocean, July.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 271

Description.—The body is stout, ovoidal, its longest diameter postequatorial in the upper
hypocone, its length 1.33 transdiameters at the widest part. The epicone exceeds the hypocone
by about 0.28 of its own length. It is slightly asymmetrical, subconical (85°) towards the apex
and rounded posteriorly. Its length above the girdle is about 0.56 of the total length of the body.
The hypocone has a length of about 0.4 of the total length. It is somewhat broader than the
epicone, with rounded sides and deeply excavated at the antapex by the distal end of the sulcus.

The exact outlines of the girdle are not shown in Pouchet’s (1894) figure which shows a deep
constriction in the region of the girdle. It appears to be without displacement and is slightly
postequatorial in position. The furrow is about 0.1 transdiameter in width, deeply impressed
with rounded borders. The suleus extends from the girdle to the antapex, where it forms a
deep, wide excavation that gives a bilobed appearance to the posterior portion of the body. The
position of the flagellar pores was not indicated.

No internal structures are shown by Pouchet except a few small spherules near the periphery.
The surface is marked by projecting ridges, about 12 across the ventral face of the body. These
seem to fade out near the apices. The color is green.

Divensions.—Length, 80+; transdiameter, 60". Pouchet (1894) gives its
dimensions as 80“ by 75. The proportions of his figure, however, do not bear
out this measurement of the transdiameter. We have taken the proportions of
his figure rather than distort it to conform to the proportions given in his text.

OccuRRENCE.—This form was figured by Pouchet (1894) from the collections
made by the ‘‘ La Manche,’’ from the Arctic Ocean near Spitzbergen, July 31,
1892, in a surface temperature of 2°6 C to 3°6 C. This is the only occurrence
on record.

CoMPARISONS.—This species is tentatively included in the subgenus Pachy-
dinium because of the general resemblance of its striations to those of other
species included therein, such as G. puniceum sp. nov. (fig. Z, 5). The nearest
approach to the cingular constriction appears in G’. coeruleum Dogiel (fig. Z, 4).
This is one of the most northern species of Gymnodinium thus far known.

Gymnodinium zachariasi Lemmermann
Text figure BB, 3

Gymnodinium palustre, Zacharias (1899), pp. 142-144, figs. 1-9.

G. zachariasi, Lemmermann (1900), p. 116; (1902), p. 260; (1903), pp. 139, 146, 149.
G. palustre, Wesenberg-Lund (1904), pp. 106, 107.

G. palustre, Dogiel (1906), p. 31.

G. zachariasi, West and West (1906), p. 92.

G. zachariasi, Entz (1910), pp. 157, 158, 162, figs. 1-12 (questionable).

G. palustre, Kolkwitz (1911), p. 346, pl. 6, fig. 2 (in part = G. palustre Sch.).
G. palustre, Klebs (1912), p. 429.

G. zachariasi, Schilling (1913), p. 16, fig. 12.

G. palustre, Fauré-Fremiet (1914), p. 41.

G. zachariasi, West (1916), p. 53.

DraGcnosis.—A small species with ovoidal body, its length 1.57 dorsoventral
diameters; girdle without displacement (?); sulcus (?) ; yellowish brown; ex-
trudes pseudopodia. Length, 44". Fresh-water lakes near Plén, Germany; the
Trish lakes; Budapest, Hungary.

bo
=~
bo

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Description.—The body is ovoidal, its greatest width posterior, and its length 1.57 dorso-
ventral diameters, at the widest part. The epicone is long, exceeding the hypocone by 0.35 of
its own length. It is symmetrically bell-shaped with rounded apex. Its length is about 0.56 the
total length of the body. The hypocone is subhemispherical in shape with a length of 0.3 the
total length of the body.

The girdle is slightly posterior to the middle of the body, having a distance from the apex
of about 0.56 of the total length of the body. Zacharias (1899) has figured only the right lateral
view of the organism, hence the displacement of the girdle and the length and position of the
suleus cannot be determined. The furrow is about 0.1 dorsoventral diameter in width and is
deeply impressed.

The most striking feature about this organism is its formation of pseudopodia. These are
thrown out from the ventral side, usually in front of the girdle, but they may arise from the
girdle or posterior to it, presumably from the suleus. They may be straight, blunt extensions
of protoplasm or they may be variously branched, and considerably longer than the body. No
evidence is given, such as food inclusions in the body, to indicate that these have a function
concerned with the nutrition of the body. The only cell inclusions noted by Zacharias (1899)
are rod-shaped, yellow-brown chromatophores closely crowded together in longitudinal lines in
the peripheral zone.

Dimenstons.—Length, 44; dorsoventral diameter, 16+; transdiameter, 32+.
It is difficult to reconcile the dimensions given by Zacharias (1899) in his text
with the dimensions of his figures. The proportions used above are taken from
his figures, while the actual dimensions quoted above are his own. His figure 1
might be interpreted as a dorsal view, but it has the same proportions as his
figures 4 to 9, which are undoubtedly lateral views. Lemmermann (1910) has
undoubtedly noted this discrepancy, as he states that the cross-section of the
body is cireular, 32# broad. The width of his (Zacharias, 1899) figures cannot
be more than 28 as they are drawn. The diameter of the cyst ranges from 25
to 100z.

OccURRENCE.—Figured by Zacharias (1899) from plankton collected in
Uklei Lake near Plon, Germany, in November. Its occurrence has also been
recorded by Entz (1910) near Budapest, Hungary, and by West and West
(1906) from Irish lakes.

CoMPARISONS.—Described by Zacharias (1899) as G. palustre Sch. and
changed to G. zachariasi by Lemmermann (1900). It differs from G. palustre
mainly in its formation of pseudopodia. The importance placed on this phe-
nomenon as an evidence of holozoic nutrition (West, 1916) would seem to be
unduly stressed, since no evidence is offered on that point in G. zachariasi.. On
the other hand abundant evidence is offered herewith to show that holozoic
nutrition is quite general throughout Gymnodinium as well as other genera, with
no signs of the formation of pseudopodia.

CHAPTER XIII

GYMNODINIIDAE: GYRODINIUM

GYRODINIUM nom. gen. nov.
Text figures B, CC-EE
Gymnodinium, Sehiitt (1895) in part, pl. 21, figs. 65-69; pl. 22, figs. 70
81, 83.

Spirodinium Sehiitt (1896), p. 5, fig. 6.

Spirodinium, Lemmermann (1899), pp. 359, 360; (1910), pp. 613, 626-628, figs. 20-22, 27.
Spirodinium, Paulsen (1908), pp. 101-103, figs. 139-141.

Spirodinium, Schilling (1913), pp. 21, 22, figs. 21, 22.

DIAGNOSIS

Gymnodiniidae with girdle a descending left spiral, displaced more than 0.2
of the total length of the body; sulcus longitudinal or with a torsion of less than
0.5 transdiameter in the intercingular area, extending from apex to antapex,
rarely with antapical loop. The nucleus is usually near the center of the hody,
filled with distinct moniliform chromatin strands; perinuclear membrane is
rarely present. Pusules usually present, opening anteriorly into the anterior
flagellar pore or posteriorly into the posterior pore, or both may be present and
connected by a canal. No nematocysts; suface striate or smooth; chromato-
phores rarely present; plasma colored; pigment granules sometimes present.
Holozoie nutrition generally; encystment in thin-walled membrane frequent.
Length, 23-1554. Marine and fresh water, eupelagic and littoral and from
arctic, temperate, and tropical seas; 48 species known.

ORGANOLOGY

Gyrodinium in its organization forms the connecting link between Gymno-
dinium and Cochlodinium, having, on the one hand, species which approach the
Gymnodinium type of girdle arrangement, as G. truncatum sp. nov. (fig. CC, 5),
and, on the other hand, forms like G. ochraceum (fig. DD, 17), with a marked
torsion of the body approaching the Cochlodinium type of structure. In the
relative proportions of epicone and hypocone it shows a range of variations
similar to that found in Gymnodinium.

Gyrodinium differs from the genus Gymnodinium mainly in the arrange-
ment of its girdle, the proximal and distal ends of which have here become
displaced anteroposteriorly more than one-fifth of the total length of the body,
and their displacement may be as great as one-half the total length. The girdle

274 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

22

Fig. CC. Gyrodinium. 1. G. caudatum sp. nov. 2. G. culeus sp noy. 3. G. pusillium (Schilling). After
Schilling (1891, pl. 10, fig. 15). 4. G. parvulum (Schiitt). After Schiitt (1895, pl. 25, fig. 84). 5. G. truncatum
sp. nov. 6. G. ovoidewm sp noy. 7. G. acutum nom. sp. noy. After Schiitt (1895, pl. 21, fig. 66). 8. G. ovwm
(Schiitt). After Schiitt (1895, pl. 25, fig. 83). 9. G. melo sp. nov. 10. G. intortum sp. nov. 11. G. falcatum
nom. sp. nov. After Schiitt (1895, pl. 25, fig. 81,). 12. G. biconicum sp. nov. 13. G. spumantia sp. nov. 14.
G. capsulatum sp. nov. 15. G. hyalinum (Schilling). After Schilling (1891, pl. 10, fig. 14). 16. G. flavescens
sp. nov. 17. G. cuneatum nom. sp. nov. After Pouchet (1885a, pl. 4, fig. 32). 18. G. foliacewm nom. sp. nov.
After Schiitt (1895, pl. 26, fig. 88,). 19. G. dorsum sp. nov. 20. G. flavidwm sp. nov. 21. G. crasswm (Pouchet).
After Pouchet (18855, pl. 26, fig. 2a). 22. G. contortum (Schutt). After Schutt (1895, pl. 21, fig. 67,). x 500.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 275

iibkies
fi] .
Sh see
SUT WHY
iN i
: ‘A Ws

Fig. DD. Gyrodiniym. 1. G. submarinum sp. nov. 2. G. pepo nom. sp. nov. After Schitt (1895, pl. 21,
fig. 69). 3. G. obtuswm nom. sp. nov. 4. G. truncus sp. nov. 5. G. schwetti (Schiitt). After Schutt (1895, pl.
22, fig. 71.). 6. G. herbaceum sp. nov. 7. G. grave (Meunier). After Meunier (1910, pl. 14, fig. 27). 8. G.
fissum (Levander). Original. 9. G. fulvum sp. nov. 10. G. longum (Lohmann). Modified after Lohmann
(1908, pl. 17, fig. 22). 11. G. viridescens sp. nov. 12. G. corallinum sp. nov. 13, G. britannia nom. sp. nov.
After Lebour (1917), fig. 10d). 14. G. spirale (Bergh.). Original. 15. G. pingue (Schiitt). Original. 16. G.
glaucum (Lebour). Original. 17. G. ochraceum sp. nov. 18. G. rubricaudatum sp. noy. 19. G. maculatum
sp. noy. 20. G. postmaculatum sp. noy. 21. G. virgatwm sp. nov. X 500.

276 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

is thus here a more or less steeply descending left spiral, usually nearer the
anterior than the posterior end, frequently occupying the middle third of the
body. In one species only, G. glaucum, is it located far posteriorly. The
amount of overlapping of the ends varies from none to about 0.5 transdiameter,
the latter amount being rare and foreshadowing the conditions in Cochlodinium
with its greater torsion of the body. The greatest amount of overlapping or
overhanging is shown in G. contortum Schiitt (fig. CC, 22).

The suleus is variable in length, usually extending from or near the apex to
the antapex in a nearly straight line or with a varying amount of torsion, less
than 0.5 transdiameter. The sulcal region forms the area for the ingestion of
food, which will probably account for the variations in length and prominence
of its borders noted occasionally in individuals of the same species. In one
species only, G. ochraceum (fig. DD, 17), it forms an antapical loop with a
torsion of 0.5 transdiameter below the distal junction of the suleus and girdle,
resembling in this respect the more highly developed forms of Cochlodinium
and Pouchetia. A greatly developed apical loop is found in G. intortum sp. nov.
(fig. CC, 10), combined with an overhang of the girdle of 0.6 transdiameter
which more closely aligns it with Pouwchetia than with other members of this
genus. Its lack of ocellus, however, excludes it from the genus Pouchetia.

The chromatin contents of the nucleus of Gyrodinium are always arranged
in moniliform threads. In two species, G. corallinum sp. nov. and G. virgatwm
sp. nov. (figs. DD, 12, 21), the nucleus is composed of two distinct regions, an
outer alveolar zone and an inner zone filled with chromatin granules, and separ-
ated by a distinct membrane. The nucleus is usually located near the central
part of the body, rarely far anteriorly or posteriorly.

The surface of Gyrodinium may be either smooth or striate, with a prepon-
derance of species showing a striate surface, differing in this respect from all
other genera in the Gymnodiniidae. The striae may be continuous, unbroken
lines or may be composed of linear series of short dashes. When pigment is
present in the body it is collected along the lines of striae and massed at the
ends of the lines, indicating a fundamental linear organization of the peripheral
eytoplasm (figs. DD, 9, 21).

The color of the cytoplasm in Gyrodinium is remarkable for its diversity
and brilliancy. It may be diffusely distributed as in G. truncus sp. nov. (pl. 3,
fig. 28), G. herbaceum sp. nov. (pl. 10, fig. 109), and G. fissum sp. noy., confined
to chromatophores, as in G. melo sp. nov. (pl. 5, fig. 50), G. foliaceum sp. nov.,
G. faleatum sp. nov., and G. pusillum (Schilling), or may take the form of pig-
ment, as in G. maculatum sp. nov. (pl. 6, fig. 62), G. corallinum sp. nov. (pl. 10,
fig. 117), G. ochraceum sp. nov. (pl. 7, fig. 76), G. virgatum sp. nov., G. post-
maculatum sp. nov. (pl. 6, fig. 64).

All the colors of the spectrum are to be found within the species of this
genus, but most of them show some shades of vellow and green. G‘. maculatum
sp. noy. (pl. 6, fig. 62), with its violet pigment, is the only species lying near
the violet end. G. biconicum sp. noy. (pl. 4, fig. 46) and G. submarinum sp. nov.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 277

(pl. 10, fig. 110) are pale glaucous blue. A larger group is found at the red end,
comprising G. postmaculatum sp. nov. (pl. 6, fig. 64), G. corallinum sp. nov.
(pl. 10, fig. 117), G. virgatum sp. nov. (pl. 10, fig. 112), G. britannia nom. sp.
nov.. G. cuneatum sp. nov., G. capsulatum sp. nov. (pl. 5, fig. 54), G. rubricau-
datum sp. nov. (pl. 10, fig. 116), and G. culeus sp. nov. (pl. 7, fig. 77), all exhib-
iting various tones of red and purple, in several cases in the form of pigment
with a greenish yellow color in the cytoplasm, as in G. corallinum sp. nov. and
G. virgatum sp. nov.

2

5 8

Fig. EE. Gyrodiniwm. 1 and 2. G. concentricum (Lebour). After Lebour (1917), figs. lla, b). 3. G. fucorum
(Kiister). After Kiister (1908, fig. 1). 4. G. fusiforme nom. sp. nov. After Meunier (1910, pl. 14, fig. 25).

5. G. mitra (Schiitt). After Schiitt (1895, pl. 21, fig. 68a,). 6. G. lachryma (Meunier). After Meunier (1910,
pl. 14, fig. 21). 7. G@. ovatum (Gourret). After Gourret (1883, pl. 1, fig. 22); magnification? 8. G. fusiforme
nom. sp. noy. After Meunier (1910, pl. 14, fig. 23). 9. @. cornutum (Pouchet). After Pouchet (1885a, pl. 4,
fig. 31). X 500.

Of the remaining thirty-seven species ten have been described without
reference to their color and the others fall within the green-yellow part of the
spectrum, varying from the mixed yellow green of G@. fisswm (Levander) (pl. 9,
fig. 95) and G. obtusuwm nom. sp. nov. to the green of G. herbaceum sp. noy.
(pl. 10, fig. 109), on the one hand, and on the other the yellow of G@. caudatum
sp. nov. to the deep yellow ochre of G. ochraceum sp. nov. (pl. 7, fig. 76). In
the green and yellow group the latter color predominates, sixteen species exhib-
iting various shades of yellow and yellow ochre and seven exhibiting a green
color with three of intermediate tones. One species only, G. spumantia sp. nov.
(pl. 7, fig. 72), shows the presence of melanin.

Gyrodinium shows a distinct advance over the genus Gymnodinium in that
the number of species possessing chromatophores has been reduced and the
number of those possessing colored pigment has been increased. As in that
genus, so also in Gyrodinium the latter group is composed of those species whose

278 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

color places them near the red end of the spectrum, a fact which links them
with the further evolution of the Gymnodinioidae in the more highly specialized
Cochlodinium, and in Pouchetia, and Erythropsis.

The species of this genus are, most of them, holozoic in nutrition. Four
species only possess chromatophores, G. melo sp. nov., G. falcatwm sp. nov.,
G. pusillum (Schilling), and G. foliaceum sp. nov. Of these G. melo and G.
foliaceum show undoubted evidences of holozoic nutrition, such as the presence
of food masses and vacuoles, products of metabolism, in the cytoplasm. The
same conditon holds true in other Gymnodiniidae, as in Amphidinium scissum,
A. corpulentum, Gymnodinium agile, G. flavum, and G. herbaceum. Of the
remaining species most of them show evidences of holozoic nutrition, such as
food balls, oil globules, vacuoles, and refractive granules in the cytoplasm, the
accumulated products of metabolism or indications of periodic feeding and
digestion.

Encystment is probably in many cases due to the ingestion of large food
masses and follows upon it, the cyst being formed to meet the needs of the
organism for a quiet period for its digestion. As the cyst wall is first formed
it closely invests the body, becoming expanded at a later stage with the accumu-
lation of fluid within it by osmosis. In many cases of encysted individuals, those
enclosed in apparently newly formed cysts usually show the presence of food
bodies as in G. truncatum (pl. 1, fig. 3), while others, in which the cyst has
become greatly enlarged, may be entirely free from food bodies, as are indi-
viduals just emerging from the cyst.

DISTRIBUTION

Gyrodinium, like Gymnodinium, is widely distributed, but is found princi-
pally within the warm temperate waters. Two species only have thus far been
described from fresh water, G. hyalinum (Schilling) and G. pusillum (Schil-
ling) near Basel, Switzerland (Schilling, 1891); the former species is also
recorded from the Danish lakes by Wesenberg-Lund (1904). Of the remaining
twenty-three species three have been found within Arctic waters, G. grave
(Meunier), and G. lachryma (Meunier) by Meunier (1910) near Nova Zembla,
and G. crassum (Pouchet) by Pouchet (1894) near Spitzenbergen. One species,
G. spirale (Bergh), has been recorded from the Indian Ocean by Karsten (1907).
The remainder are inhabitants of the warm and cool temperate waters. The
larger number of these come either from the Atlantic or the Bay of Naples, the
localities from which Schitt’s (1895) species were obtained. These are G.
acutum. G. contortum, G. foliaceum, G. obtusum, G. ovum, G. parvulum, G. pepo,
G. pingue, G. mitra, all figured and described by Schutt as in the genus Gymno-
dinium, and the following species described by Pouchet: in 1883, G. fissum; in
1885a, G. crassum, G. cuneatum (as Gymnodinium gracile), and in 1885b, G.
spirale, all as in the genus Gymnodinium. From the Mediterranean at Cette
Pavillard (1905) records G. crassum (Pouchet), Gourret (1883) from Marseilles

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 279

records G. ovatum (Gourret), and Schroder (1900) adds G. obtuswm and G.
spirale from Naples. The last named species is also recorded from the Baltic
by Ostenfeld (1913), as is also G. longum (as Cochlodinium longum Lohmann)
by Lohmann (1908) and G. fissum by Levander (1894).

~ Lebour (1917) has recorded the following from Plymouth Sound, England:
G. crassum, G. glaucum, G. britannia (as Spirodinium spirale var. acutum),
G. spirale, and one species, G. concentricum, which we place in the species
incertae sedis. To these records Ostenfeld (1908) has added one of G. fissum
from the Aral Sea with a question as to the identity of the species.

Thus far no record has been made of Gyrodinium in the Pacific. We record
in this paper the occurrence in the plankton off San Diego and La Jolla, Cali-
fornia, of the following species previously described: G. contortum (Schutt),
G. fissum (Levander), G. glaucum (Lebour), G. obtusum (Schutt), G. pingue
(Sehiitt), G. sphaericum Calkins, G. spirale (Bergh), and twenty-three new
ones as follows: G. biconicum, G. capsulatum, G. caudatum, G. corallinun,
G. culeus, G. dorsum, G. flavescens, G. flavidum, G. fulvum, G. herbaceum, G.
intortum, G. maculatum, G. melo, G. ochraceum, G. ovoideum, G. postmacu-
latum, G. rubricaudatum, G. spumantia, G. submarinum, G. truncatum, G.
truncus, G. virgatum, and G. viridescens.

Two species stand out in these records as cosmopolitan in distribution, G.
spirale (Bergh) and G. fisswm (Levander), the former occurring in the Atlantic,
Pacifie, and Indian oceans and the Mediterranean and Baltic seas, and the latter
in the Atlantic and Pacific oceans and the Baltic Sea. The species having the
widest range in temperate zones is G. crassum (Pouchet), recorded from the
Mediterranean, the Atlantic, and the Arctic near Spitzbergen.

HisrortcaL Discussion

In his ‘‘Peridiniales’? in Engler and Prantl’s Pflanzenfamilien Schutt
(1896) established the genus Spirodinium for that section of the genus Gymno-
dinium in which the girdle forms a steep spiral and the sulcus or longitudinal
furrow is a nearly straight line, with the result that the two flagellar pores are
widely separated by the displacement of the distal end of the girdle posteriorly
from the proximal. He named one species only, S. spirale (Bergh), as repre-
senting the genus. His name was later accepted by Lemmermann (1899, 1910),

Paulsen (1908), Schilling (1913), and others working on the Dinoflagellata.

Unfortunately Schiitt did not consider the possible preoccupation in zoolog-
ical literature of his generic name, which may have been available from the
botanical standpoint and was certainly appropriate and morphologically signifi-
cant. However, many if not all of the species of this genus are holozoic, and
in any event it is desirable to avoid preoccupation of generic names on both
the plant and the animal side in the case of generic names among the flagellates.

In 1890 Fiorentini had used the generic name Spirodinium for a ciliate
parasitic in the coecum of the horse, with S. equi as the monotype. It is there-

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

bo
(os)
Oo

fore necessary, according to the zoological Code of Nomenclature, to displace
Schiitt’s Spirodinium with a new generic name. We accordingly propose the
appropriate and suggestive name Gyrodinium in lieu of Spirodinium. Its type
species is Gyrodinium spirale, described as Gymnodinium spirale by Bergh
(1881D) and used by Schiitt (1896) as his type of the genus Spirodinium.
Schutt (1896), in thus calling attention to the need of revision of the genus
rymnodinium, failed to follow it up by removing from the genus those species
which he had himself described earlier (1895) as species of Gymnodinium, but
which possessed the characteristics of his new genus. Lemmermann later (1899)
transferred some of these to Spirodinium as follows, which we cite with our
own allocation:
Gymnodinium cornutum Sehiitt = Spirodinium schuetti (Schiitt) Lemm. = Gyrodinium
schuetti (Schiitt) Kofoid and Swezy.
G. spirale var. mitra Schiitt = Spirodinium spirale var. mitra (Schitt) Lemm. = Gyro-
dinium mitra (Schiitt) Kofoid and Swezy.
G. spirale var. obtusa Schiitt = Spirodinium spirale var. obtusum (Schiitt) Lemm. =
Gyrodinium obtusum (Schiitt) Kofoid and Swezy.
G. spirale var. pepo Schiitt = Spirodinium spirale var. pepo (Schiitt) Lemm. = Gyrodi-
nium pepo (Sehiitt) Kofoid and Swezy.
G. spirale var. pinguis Schiitt == Spirodinium spirale var. pingue (Schiitt) Lemm. =
Gyrodinium pingue (Schiitt) Kofoid and Swezy.

In addition to these species we have also transferred to Gyrodiniwm the
following species described by Schiitt (1895) as species of Gymnodinium:

Gymnodinium contortum Sehiitt—= Gyrodinium contortum (Schiitt) Kofoid and Swezy.
G. opimum Schiitt = Gyrodinium contortum nom. sp. nov.

G. ovum (Sehiitt) = Gyrodinium ovum (Sehiitt) Kofoid and Swezy.

G. parvulum Schiitt = Gyrodinium parvulum (Sehiitt) Kofoid and Swezy.

G. viride Schiitt = Gyrodinium foliaceum nom. sp. nov.

G. fusus Schiitt = Gyrodinium falcatum nom. sp. nov.

Lemmermann (1899 and 1900) also transferred to Spirodinium the following
species described by the authors specified as species of Gymnodinium, which we
cite here with our own allocation:

Gymnodinium spirale var. nobilis Pouchet = Spirodinium spirale var. nobilis (Pouchet)
Lemm. = Gyrodinium, indeterminable.

G. spirale var. cornutwm Pouchet = Spirodinium cornutum (Pouchet) Lemm. = Gyrodi-
nium cornutum (Pouchet) Kofoid and Swezy.

G. crassum Pouchet = Spirodinium crassum (Pouchet) Lemm. = Gyrodinium crassum
(Pouchet) Kofoid and Swezy.

G. hyalinum Schilling = Spirodinium hyalinum (Schilling) Lemm. = Gyrodinium hyali-
num (Schilling) Kofoid and Swezy.

G. pusillum Schilling = Spirodiniwm pusillum (Schilling) Lemm.—= Gyrodinium pusillum
(Schilling) Kofoid and Swezy.

G. fissum Levander = Spirodinium fissum (Levander) Lemm.=Gyrodinium fissum
(Levander) Kofoid and Swezy.

The number of species added later to the genus Spirodinium are few. In
1910 Meunier described Spirodinium fusus, overlooking the fact that the species
name was preoccupied by Schitt’s (1895) species. This we have designated

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 281

Gyrodinium fusiforme nom. sp. nov. He also described Spirodinium lachryma
and Spirodinium grave, both of which we here transfer to Gyrodinium. Lebour
(1917b) described Spirodinium glaucum and a doubtful species as Spirodiniwm
concentricum, which we here transfer to Gyrodinium; also a form as Spiro-
dinium spirale var. acutum, which is distinct from Schiitt’s species; this we
have designated Gyrodinium britannia nom. sp. nov.

In addition to these we have transferred to Gyrodinium the following species
originally allocated elsewhere but showing undoubted Gyrodinium characters:

Gymnodinium ovatum Gourret (1883) = Gyrodiniwm ovatum (Gourret) Kofoid and
Swezy.

Cochlodinium longum Lohmann (1908) = Gyrodiniwm longum (Lohmann) Kofoid and
Swezy.

Kiister (1910) deseribed a form, as Gymnodinium fucorum, which clearly
belongs to this genus. His figures and description are inadequate for specific
diagnosis, and we therefore place it among the species incertae sedis.

Twenty-one species have been previously described in other genera and are
here included in Gyrodinium, as follows: G. acutum (Schutt), G. contortum
(Schiitt), G. cornutum (Pouchet), G. crassum (Pouchet), G. fissum (Levander),
G. foliaceum (Sehiitt), G. glaucum (Lebour), G. grave (Meunier), G. hyalinum
(Schilling), G. longum (Lohmann), G. lachryma (Meunier), G. obtuswm
(Schiitt), G. ovatum (Gourret), G. ovum (Schiitt), G. mitra (Schutt), G. par-
vulum (Schiitt), G. pepo (Schiitt), G. pingue (Schitt), G. pusillum (Schilling),
G. schuetti (Sehiitt), G. spirale (Bergh).

We add to these in this paper the following twenty-three new species: G.
biconicum, G. capsulatum, G. caudatum, G. corallinum, G. culeus, G. dorsum,
G. flavescens, G. flavidum, G. fulvum, G. intortum, G. herbaceum, G. maculatum,
G. melo, G. ochraceum, G. ovoideum, G. postmaculatum, G. rubricaudatum, G.
spumantia, G. submarinum, G. truncatum, G. truncus, G. virgatum, G. viri-
descens.

The following species described under other names are for various reasons
fully outlined in the discussion of the several species included in Gyrodinium
under new names as follows: Gyrodinium britannia nom. sp. nov. (= Gymno-
dinium spirale var. acutwm, Lebour, 1917b), G. ecuneatum nom. sp. nov.
(=Gymnodinium gracile, Pouchet, 18850), G. faleatum nom. sp. noy.
(= Gymnodinium fusus, Schiitt, 1895, in part), and G. fusiforme nom. sp. nov.
(= Spirodinium fusus, Meunier).

SuBGENERA OF Gyrodinium

Two subgenera based upon surface differentiations, as in Gymnodinium,
may be separated in Gyrodinium. There are no species in this genus with the
thick alveolar ectoplasm found in the species of the subgenus Pachydinium of
Gymnodinium. The basis of separation of the two subgenera is the presence
or absence of longitudinal striations in the ectoplasm. The more primitive sub-
genus Laevigella subgen. nov. lacks such markings. Its type species is (ryro-
dinium caudatum sp. noy. and it includes in addition twenty-four other species.

282 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The more highly differentiated subgenus with striate pellicle has for its type
species Gyrodinium spirale (Bergh), the type of Gyrodinium sensu latu. In
addition to this it includes twenty-two other species. This subgenus contains
the most of the species with maximum displacement of its girdle and torsion of
the body, highest coloring, and development of pigment.

In addition there are imperfectly known species which must for the present
be left unassigned in species incertae sedis to wit: G. fucorum (Kuster) and
G. concentricum (Lebour).

Suspcenus 1. Gyrodinium (sensu strictu) subgen. nov., fig. DD

ryrodinium with surface striate with parallel longitudinal striae. Type
species is G. spirale (Bergh). This subgenus contains besides the type the
following species: G. britannia nom. sp. noy., G. corallinum sp. nov., G. crassum
(Pouchet), G. cuneatum nom. sp. nov., G. fissum (Levander), G. fulvwm. sp.
noy.. G. glaucum (Lebour), G. grave (Meunier), G. herbaceum sp. nov., G.
longum (Lohmann), G. maculatum, G. obtusum nom. sp. noy., G. ochraceum
sp. nov., G. pepo (Schutt), G. pingue (Schutt), G. postmaculatum sp. nov.,
G. rubricaudatum sp. noy., G. schuetti (Schutt), G. submarinum sp. nov., G.

truncus sp. noy., G. virgatwm sp. nov., G. viridescens sp. nov.

SupGenvs 2. Laevigella subgen. noy., fig. CC

Gyrodinium with surface free from longitudinal parallel markings, with or
without chromatophores. The type species is G. caudatum sp. nov. This sub-
genus includes besides the type the following species: G. acutum (Schiitt),
G. biconicum sp. nov., G. capsulatum sp. nov., G. contortum (Schutt), G. cor-
nutum (Pouchet), G. culeus sp. nov., G. dorsum sp. noy., G. falcatum nom. sp.
noy., G@. flavescens sp. noy., G. flavidum sp. nov., G. foliaceum nom. sp. noy.,
G. fusiforme nom. sp. nov., G. intortum sp. nov., G. hyalinum (Schilling), @.
lachryma (Meunier), G. melo sp. nov., G. mitra nom. sp. noy., G. ovoidewm
sp. nov., G. ovatum (Gourrett), G. ovum (Schutt), G. parvulum (Schiitt), G@.
pusillum (Schilling), G. spumantia sp. nov., and G. truncatum sp. nov.

Key TO THE SPECIES oF Gyrodinium

1. Surface free from striae or other markings, with or without chromatophores —..........

wt NR 8 ee te ee I ara ee es (subgenus Gyrodinium) 7
I. Surface striate, chromatophores absentee cn ee eee (subgenus Laevigella) 2
25 (Chromatophores: presents esc s ence cers ere ce ee ee crea 3
2. Chromatophores absent << ..2.-.2225 25. ceccsnccsesces 2s = cecnseetecscseenec ove sceece ee see ante ere co weee sence trace ee ee 6
3». Chromatophores':y elbow .c:-c sere sc cect snc eee case eee ace cee eee eee ra eee 4
3. Chromatophores. green <-.-os-_-.acscescccce ose s eaves eases onetcn ge resue reece snacasserasnen) vodeas tee etena/ererwer ater nesae eens 5
4. Chromatophores small, rod-shaped, yellow ochre ................-....-.------ falcatum nom. sp. noy.
4. ‘Chromatophores’ diskdikes yellow sss cece eee ener pusillum (Schilling)

NAN DH oO on

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wee O OS

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 283

. Body rotund ellipsoidal, girdle with distinct overhang, length over 60 —...... melo sp. nov.

Se Oc yanouund len gtheless sth aril G 0 pupeeeees ae e eeemne Sern een foliaceum nom. sp. nov.

Meal ASTN a COL OTC CG meee neta rec eee ee Re wn ates ier Bt 0, ds ka ee ae ee 7

‘eColorlessysmalllsinesh= walters peCles so-eeeeee eee eee ees eee hyalinum (Schilling)

Ba (0) iy Yoesl A () rrp 20 eerie eae ae RN rc as een eer aes enn YE EW ee ee 8

Py Bless ithe l'£0 pal mn perenne Sata See ee ee i. ect bo Det ns oh ee A 9

. Body slender fusiform, peripheral zone of rodlets — acutum (Schiitt)

. Body subovoidal, no peripheral rodlets, plasma vacuolated spumantia sp. nov.

BEV Gy Trem tale arm) () pag O11 Soe ee re ae nc are ce oes z cas ee ee

oid epeSy At aI SS) Uy Ss ee ee eee eee
Sulcushwithwtorsionaot,0!5) transdiame ter) ssc... ee ss ee eee

ROU CUS WAL OUtMGOLSI ON eet eee nce te were 2 Gen LVAELES § 1h GET 2 ED eee eee, JOS

~Gurdledisplaceds Ose] engtio fe boys es. eset

. Girdle displaced less than 0.5 length of body

ES OG VaePUSTT OMIT greree te ser ae crt = tae tees teers, Sheth eR eae Oe ee.

mS OCLyger-0 GUT cme FEIT S01 Gl all emcennreees see eee ee cere ee re ee flavidum sp. nov.

Se ociyanwathwa tbe ate maples erscs teste te oot ene ener onsen ee fusiforme nom. sp. nov.

. Body with blunter apices, antapex with flaps or suleus -.........-.... cornutum (Pouchet)

SP OLLCUS mWALIILORSTON gees eee cere eet nie a eats Seen eet eee eee eee ee a ee ee 15

SULCUS Wal GH OUIER LOTS 10 Tipetee teeta ree sent tote eek teed eed nee NE ee aan eee TATE 18

METLOLS ONO Le SU CUS OTe) ULL eee aeae noe ne nes enna a te eee ne ee eee intortum sp. nov.

FM OTST OL CSE ul ata OMG) WET p ase nae eae eee serene cn Se ee ee 16
. Length of body less than 2 transdiameters, color yellow -...........-....--. flavescens sp. nov.
mene theciahodyamorest hanya mtr ari sciaine Ge Ts peste teen ena eee 17
. Length of body 3.5 transdiameters, epicone attenuate —..........-.------ biconium sp. noy.

17. Length less than 3 transdiameters, epicone stouter —._....-.-.-.---------------- ovatum (Gourret)

Somallespectess lLessiul aries 5 poy lie) Cr Ot haeeseesee eee es rene eee ee Ee oa ee ene ee ate ae aoe 19

Meer oben Ore at aaa esc) presses ere eee AC EAE ube tea fu Va EATS. Oe ee 20

PBbodvastoutmlencthmele+atransdiamecers yess eens eee ne eee nine oe ovum (Schiitt)

. Body more slender, length 2.2 transdiameters ............----.----.--1:20+--+0-00--- parvulum (Schiitt)

Be VOSeRCOlOned mon ANTI ES apy OSC bee se see esa es ae eee eee ee ener culeus sp. nov.

Mp Nomnoseecolored ioral es xssestas sss neten freee sec tae scree ee pert fac rece Deno eee raeee er es eee 21

. Girdle displaced more than 1 transdiameter .....-........-.--.22+-2--+--1--++-1------++ mitra nom. sp. nov.

a Gindlemdisplacedmlesss thameelertrans claim ce rissa tee neon eeseeeeen eee een E 22

PRPADICesPLOLONGedsint rOUMG CO MOINS) eee seer re cee eee ee eee caudatum sp. nov.

MAPA CS UTIO Uayp EO OV EC meee ter ee meena sae nee ee he UO oe ce re REL eae cep nee ee sep cea daea natn. oe Der 23

bodys broadly: bicomieal) yamtapexs pou ted sence nese ae ceeeae cesses ences truncatum sp. nov.

5 [exayehy eilbiposcer kal, Eyoreerersy lomopVolllyys aeceywaKo Kee) Cee see ear eee cee pon See eee eee Pe 24

Beenie temMOrenti ares ey bn aris Ain ClOIS peeresee sess eee te eee eres te cee oe seee nee eee meee dorsum sp. noy.

Se ienatheless mth anil osLTATISGIAMELELS \c2c0ca-neces-ceee ae -ceeac suse cseaceceendusucteceecccecocev ee sae eeeeseceereevareseecee 25
Poe, (Oe Kayes yager cana way she5 oN ye, VEN AY 0 ee ce ovoideum sp. nov.
PRS (CVE OPA M ALS LIE cs cee ee Eo Pe ere capsulatum sp. nov.
27. Striae on epicone only, rose red pigment .................-.2.-----1--s02see0-=-- cuneatum nom. sp. nov.
27. Striae on both epicone and hypocone .................-----s-e-cees--0+0++ feo Se etna 5 een ee USTED 28

bo
CO

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

28. Darge’species more’ than! QO perma en others
28). Notanoré than WOOpean Vem getha osecee ee eee ee ee
29: sength amore) thaml 3m trams cian eb ers) 2a cecc eee eee ee
29: Wength'lesstthanwohtransdiamm eters ssc EE
30. Color bluish, girdle displaced 1.75 transdiameters ~..............--.-2-.-2------- submarinum sp. nov.
30. Color yellowish with carmine pigment, displacement 1.45 transdiameters

Fhe Se, RE ee Se ee britannia nom. sp. noy.
Sil, Wathiccorallipre dipper erat eee ee corallinum sp. noy.
Sil. No: neds potgmm exits. Fs ae cata cek Spce on
32) lenethuless#tihan) 2 qiranse 1am Cte rs. sso see eee CL schuetti (Lemm.)
32. henge th! morenthane atransdi amet ers) ax cesses eens eee eee ee
33. With seattered ochraceous pigment granules —___.-.-.-.-------------eeeeeee ochraceum sp. nov.
dos (NO: OcGhraceOUuSt Tan Ules) 2c eee ee cate eee ee
34. Length 165, epicone stout, girdle displaced 0.92 transdiameter -......... crassum (Pouchet)
34. Length 105-150p, epicone more tapering, girdle displaced 1.2 transdiameter —-.......

BS 9 label i 8 oo aI Ste SOS ey Re ee spirale (Bergh)
353 Medinmmi’sizedispecies so v.era 0 poerrae | ern orth geese see oes eee nn era rma one nee ee
SOR SMA es pecles ap] ess ital arn ye eo Aaa) Or eee me
363) Wath scatteredscoralamed sp igi emit ee eee ae
BGR No med spiament. SOME TLIES po UTD LTS Is ese eee ee
Si. peiementyscattered alone striae: secs eee virgatum sp. nov.
Sil ETM EN ty 1 ASSe Cle eats eA GB Cee rubricaudatum sp. nov.
36.) Pip lash Or, eva Olet ce -2 8 setae oes oe ese ee rr ae
38: (Color yellow; af ‘present cso see. o icc ce eee a ee
39. Color amaranth purple, sometimes massed at antapex —.........--. postmaculatum sp. nov.
39. Color violet purple, blotches on the epicone .............-..-.-----------c--s-ee0-0-0-+ maculatum sp. nov.
40: (Girdle displaced alstransdiameter, (Or) ra rey eee eee ee
40° (Girdle: displaced’ less; than=Itransdiamie terse ese ee
41. Minutely striate, length 1.75 transdiameters —___.........----.----------- obtusum nom. sp. noy.
41. Coarsely striate, length 2.7 transdiameters ...........--..-----c--:---ce-e-ceeeeeeee longum (Lohmann)
42. Hpiconé mot silatterned): 2.:-= 222002 Fe et ee ae
49° Bipicone flattened> truncate’ bod yastou tes ee eee ee truncus sp. nov.
43: ipicone: contracted! to) acutey.om blunts Om eee ee ee ee
43°. Hpieone: broadly mowrnd dl 25 ceo eee eee ee
44. Epicone bluntly pointed, striae similar on epicone and hypocone —.............. pepo (Schiitt)
44. Epicone acute, striae unlike on epicone and hypocone -..........--.---------------. fulvum sp. nov.
45, Meng thls iam sdiam eters) ee ease ees ee grave (Meunier)
45; mene thol 8s tran sditam eters: cee ee cee eee eae fissum (Levander)
46. -Girdlexpostmeditan: 22%. <2 sc ee glaucum (Lebour)
46... Girdle aot: postin edi ain sao asc 5 ae ee
41. Broximalvendofoirdle star anterior ees eee Viridescens sp. nov.
47. Proximal end of girdle at least 0.25 total length from apex —__...------ 22-22 -eeene eee eee
48. Girdle displaced 1 transdiameter, length 38. .......--.-.-----------c--e-seeeeeeeeeo-=- herbaceum sp. nov.
48. Girdle displaced 0.75 transdiameter, length 51p -.....-.---2-------------eeeeeeeeeeee pingue (Schiitt)

31

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA

bo
oo
oO

Gyrodinium acutum (Schiitt)
Text figure CC, 7

Gymnodinium spirale var. acuta Schiitt (1895), pl. 21, fig. 66.

Spirodinium spirale var. acutwm, Lemmermann (1899), p. 359.

S. spirale var. acuta, Schroder (1900), p. 13.

S. spirale var. acuta, Pavillard (1905), p. 47.

Not Spirodinium spirale var. acutwm, Lebour (1917b) (= Gyrodinium britannia nom. sp.
nov.).

Dracnosis.—A large species with slender, fusiform body, its length 3.82
trausdiameters; girdle a descending left spiral with slight overhang and dis-
placement of 0.93 transdiameter; sulcus extending from apex to within a short
distance of the antapex. Atlantic (?) or Bay of Naples.

DescripTion.—The body is slender fusiform, wider posteriorly, tapering to both apices, its
length 3.32 transdiameters at the widest part, which is in the posterior third of the body. The
hypocone exceeds the epicone in size, its length being greater by 0.12 of its own length and its
transdiameter by 0.09. The epicone is elongate conical, about 32°, with a narrow, blunt apex.
It has a length on the left and right sides of 0.32 and 0.60 respectively of the length of the body.
The antapex is slightly wider than the apex and blunt.

The proximal end of the girdle joins the sulcus at a point distant from the apex 0.32 of the
total length of the body. Its course around the body is that of a rather steeply descending left
spiral, with the distal end joining the sulcus at a distance from the apex of 0.60 of the total
length of the body. The furrow has a width of about 0.06 transdiameter and is deeply impressed
with smooth borders. The sulcus begins at the apex and extends posteriorly in a slightly sinuous
line to within a short distance of the antapex. The anterior flagellar pore is found at the junction
of the girdle and sulcus, the posterior pore midway between the distal junction and the antapex.

The nucleus is an ellipsoidal body lying near the midregion of the cytoplasm. It is filled
with coarse, moniliform chromatin strands which lie in the plane of its long axis, which is slightly
oblique to the longitudinal axis of the body. Its major and minor axes are 0.76 and 0.41 trans-
diameters in length respectively.

A small sacklike or club-shaped pusule opens into the anterior flagellar pore. The eytoplasm
is finely granular. A double-contoured periplast is shown in Schiitt’s figure (text fig. CC, 7),
but no reference is made to it in text or description. A peripheral layer of ‘‘ Randstiibschen”’
or slender rodlets occupies a large proportion of the interior of the body. These are arranged
nearly perpendicular to the surface, and probably correspond to the small blue-green rodlets
found in many of our own specimens, as in G. obtuswm (text fig. DD, 3). In the anterior part
of the body is a large, closely massed cluster of small spherules. No notes have been given by
Schiitt on the color of the organism. The surface is without striae.

Dimenstons.—Length, 143; transdiameter, 43; axes of nucleus, 33 and 19+.

OccURRENCE.—Figured by Schiitt (1895) from material secured by the
Plankton Expedition, presumably from the Atlantic or from the Bay of Naples.

SynonyMy.—This was originally figured by Schiitt (1895) as Gymnodinium
spirale var. acuta and later transferred by Lemmermann (1899) to the genus
Spirodinium as S. spirale var. acutum.

Comparisons.—This species is much larger than Gyrodinium spirale, being
143 in length as compared with 60+ to 100# of the other species. It also differs

286 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

in proportions, being more attenuate conical and lacking the distal curvatures
of apex and antapex and surface striae characteristic of G. spirale. It thus
appears to be as distinct from G. spirale as many other species of the genus.
It is closely related to Meunier’s (1910) species found in Arctic waters, G.
fusiforme nom. sp. noy. (G@. fusus Meunier) (fig. EE, 8) and G@. lachryma
(fig. EE, 6). The proportions, however, are different, particularly so in the
case of the latter species, with its broad, blunt posterior end and slender atten-
uate anterior end. The location of Schiitt’s species is entirely unknown and the
temperature relations of these species cannot be compared.

Gyrodinium biconicum sp. nov.
Plate 4, figure 46; text figure CC, 12

DiaGnosis.—This is a small species with slender fusiform body, its length
3.07 transdiameters; girdle a descending left spiral, displaced 0.57 transdiam-
eter; sulcus extending from apex to antapex, with torsion of 0.5 transdiameter ;
color, pale glaucous blue. Length, 68. Pacific off La Jolla, California, July.

Description.—The body is slender fusiform, tapering sharply anteriorly, less so posteriorly,
its length 3.57 transdiameters at the widest part. The epicone exceeds the hypocone in length
by 0.18 of its own length. It is slender conical, about 45°, with a slight sinistral flexure above
the anterior pore region. It has a length on the left and right sides of about 0.35 and 0.77
respectively of the total length of the body. The hypocone is slightly broader than the epicone,
its posterior end forming a cone of about 70°, rounding anteriorly. The entire body has a slightly
sigmoid curve in its general outline with the concavity on the right face.

The proximal end of the girdle meets the sulcus at a distance from the apex of 0.35 of the
total length of the body. It follows a descending left spiral course around the body and its distal
end joins the sulcus at a distance from the apex of 0.77 of the total length of the body, being
displaced about 1.57 transdiameters, and with an overhang of about 0.25 transdiameter. The
furrow has a width of about 0.15 transdiameter, and is deeply impressed with smooth borders.
The sulcus is a narrow, shallow trough extending from the apex to near the antapex in a sigmoid
curve which gives it a torsion of about 0.5 transdiameter. It terminates near the left side of the
antapex. The anterior flagellar pore opens at the anterior junction of the suleus and girdle and
the posterior pore slightly below the posterior junction. The transverse flagellum traverses
nearly the entire length of the girdle and the longitudinal flagellum has a length about equal to
that of the body.

The nucleus is a spheroidal body located near the center of the organism. In the individual
figured it was elongate ellipsoidal, evidently a predivision stage. Its axis in the other specimens
was about 0.57 to 0.73 transdiameter in length.

A large globular pusule opens into the anterior flagellar pore, a smaller sacklike one into the
posterior pore. The cytoplasm is very clear and transparent with few food bodies. In the apical
region of both individuals an irregular, light yellow, refractive body was located. In the
peripheral zone are numerous minute, blue-green oil droplets. The general color of the organism
is a diffused pale glaucous blue. No striations or other surface markings were present.

Drvensions.—Length, 52-68; transdiameter, 15-194; axes of nucleus, 13
and 11+.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 287

OccurRENCE.—The first individual was taken July 13, 1917, with a No. 25
silk net, in a haul 1.25 miles off La Jolla, California, from 50 meters to the
surface and in a surface temperature of 20°6 C. It was again observed in a
haul made July 23, 6 miles off La Jolla, from 80 meters to the surface and in
a surface temperature of 20°8 C,

CoMPARISONS.—This species in its lack of striae on the surface and arrange-
ment of girdle stands close to G. mitra (fig. HE, 5) and G. fusiforme (fig.
ER, 8). It differs from them, however, in its proportions, overhang of girdle
and torsion of the body. In the latter respect it recalls G. spirale (fig. DD, 14),
without having the surface striae of that species. It is the only species in the
genus with its general color blue, the dull glaucous blue of G. swbmarinum
appearing almost green. It does not, however, approach the clear cornflower
blue of Gymnodinium coeruleum.

Gyrodinium britannia nom. sp. noy.
Text figure DD, 13
Spirodinium spirale var. acutum, Lebour (19176), p. 194, fig. 10d.

Draanosis.—A large species with long, fusiform body, its length 3.29 trans-
diameters; girdle a descending left spiral displaced 1.42 transdiameters; sulcus
extending from apex to antapex (?) ; surface sparsely striate; carmine-colored
pigment. Length, 145. Plymouth Sound, England, August.

Derscription.—The body is long, slender fusiform, widest in the middle and tapering at both
apices, its length 3.29 transdiameters at the widest part. The hypocone exceeds the epicone in
length by about 0.26 of its own length. The epicone is subconiecal, about 50°, with slightly convex
sides and blunt, subsymmetrical apex. It has a length on the left and right sides of the sulcus
of 0.17 and 0.59 respectively of the total length of the body. The hypocone is more slender
posteriorly than the epicone with a more pointed antapex. It is elongate conical posteriorly,
about 45°, with a length on the left and right sides of 0.79 and 0.38 respectively of the total
length of the body.

The girdle joins the suleus at a distance from the apex of 0.17 of the total length of the body.
It sweeps around the body in a descending left spiral course, displaced posteriorly 1.42 trans-
diameters. The furrow is wide, about 0.09 transdiameter, and deeply impressed. The sulcus is
not definitely marked off as such in Lebour’s (1917b) figure, but evidently extends from near
the apex to or near the antapex. The flagella and pores are also omitted from her figure.

The nucleus is ellipsoidal and located near the central part of the body. It is filled with
short, moniliform chromatin strands, which are parallel to the longitudinal plane of the body.
Its major and minor axes are 0.59 and 0.5 transdiameters in length respectively. The surface of
the body is covered with equidistant, longitudinal lines, figured as about 15 across the ventral
face. These lines are further marked off by granules of carmine-colored matter, strung along
their length like beads on a string. These are most numerous on the epicone, especially near the
apex, with a few scattering granules on the posterior half of the hypocone.

€

Divenstons.—Length, 145; transdiameter, 44; axes of nucleus, 25# and 21+.
OcCURRENCE.—Figured by Lebour (1917)) from Plymouth Sound, England,
5 ’ . Se)
in August.

288 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

SynonyMy.—This form was described by Lebour (1917b) as Spirodinium
spirale var. acutum Schitt. It differs from Schiitt’s figure (1895), however,
in its proportions and more strikingly in its coloring, and also in its cytoplasmic
structure. Surface striae are apparently lacking in Schiitt’s species. These
differences seem to be too great to allow it to remain with Gyrodinium acutum,
hence we propose for it specific rank with the name G. britannia.

Comparisons.—In the possession of red pigment this species stands near
G. corallinum (pl. 10, fig. 117) and G. virgatum (pl. 10, fig. 112), differing from
them, however, in other important respects, such as proportions and shape of
body and type of nucleus (see figs. DD, 12, 18, 21).

Gyrodinium capsulatum sp. noy.
Plate 5, figure 54; text figure CC, 14

DraGnosis.—This is a small species with broadly ovoidal body, its length
1.26 transdiameters; girdle submedian, a descending left spiral displaced 0.38
transdiameter; sulcus short on epicone, extending to antapex; color, orange
green. Length, 454. Pacific off La Jolla, California, July, August.

Description.—The body is broadly ovoidal, with broad, rounded apices, widest posteriorly,
its length 1.26 transdiameters at the widest part. The epicone exceeds the hypocone in length
by about 0.2 of the total length, but not in volume, as its transdiameter is narrower. The epicone
is smoothly rounded with broad apex. It has a length on the left and right sides of 0.4 and 0.69
respectively of the total length of the body. The hypocone is hemispherical in shape, somewhat
wider than the epicone, with smoothly rounded or slightly notched antapex.

The girdle is submedian in position, its proximal end joiing the suleus at a distance from |
the apex of 0.4 and its distal end 0.69 of the total length of the body. It follows a descending
left spiral course around the body, its distal end displaced about 0.38 transdiameter. The furrow
is wide, about 0.08 transdiameter in width, and is deeply impressed with smooth, overhanging
borders. The suleus invades the epicone for a short distance, narrowing rapidly from a wide
trough at the girdle to a slender line. Posterior to the anterior flagellar pore the overhanging
borders of the suleus nearly obliterate the furrow, immediately spreading out again to form a
wide, deep trough which reaches to the antapex. Its borders are mobile, overhanging, giving a
slightly sinuous line to the course of the suleus. The anterior flagellar pore is found about 0.5
of the width of the girdle posterior to the proximal junction of the girdle and sulcus, and the
posterior pore is shghtly behind their distal junction.

The nucleus is a large, ellipsoidal body situated immediately below the equatorial plane, with
its major axis slightly oblique to the short axis of the body. It is filled with fine, moniliform
chromatin strands following the course of its major axis. Its major and minor axes are about
0.73 and 0.44 transdiameter in length respectively.

In the individual figured pusules were not evident. In another specimen a single long, tube-
like pusule opened into both the anterior and posterior pores. The cytoplasm is finely granular
and transparent. Scattered through it are greenish yellow patches of irregular shape and a
few oil droplets of the same color. Near the periphery are numerous club-shaped vacuoles filled
with the pink fluid such as is found in the pusules. These appear to be in the process of opening
to the exterior. The color is pale green yellow distributed throughout the cytoplasm. Beneath
the pellicle is a layer of orange color which forms a border around the body in optical section.
A clearly marked, double-contoured periplast forms the periphery of the body. Around the
body and closely following its contour is a hyaline thin-walled cyst. A second cyst is formed
around this, much larger than the first and closely following its outline.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 289

Drmensions.—Leneth, 45-50/; transdiameter, 33-40; major and minor axes
of nucleus, 25# and 28; length of outer cyst, 62+.

OccuRRENCE.—The individual figured was taken July 2, 1917, 6 miles off
La Jolla, California, with a No. 25 silk net, in a haul from 60 meters to the
surface and in a surface temperature of 21°9 C. It was noted again on August
6, in a surface haul 4 miles offshore and in a surface temperature of 21:2 ©.

CoMPARISONS.—This species stands nearest to Gymnodinium in its type of
girdle arrangement, having somewhat less displacement than other species of
the genus. The orange color in its peripheral layer recalls the same color and
location in Gymnodinium dogieli (pl. 3, fig. 34) and G. pachydermatum (pl. 38,
fig. 32), without, however, being correlated with the characteristic ectoplasmic
differentiation of those species.

Gyrodinium caudatum sp. noy.
Plate 9, figure 102; text figure CC, 1

Dracnosis.— Body broadly fusiform, its length 1.94 transdiameters, with
apical and antapical processes subequal, very stout, the apical truncate; girdle
displaced about 0.5 transdiameter, with slight overhang; color, primuline
yellow; length, 66«. Pacific off La Jolla, California, July.

Description.—The body is broadly fusiform with abruptly contracted apical and antapical
processes, its length 1.94 transdiameters; dorsoventral and transdiameters equal. Hpicone and
hypocone are about equal. The epicone has a length on the left and right sides of 0.27 and 0.59
transdiameters respectively. It is subhemispherical above the proximal end of the girdle and
contracts to a stout apical process in the form of a truncate cone 0.27 transdiameter in length,
its basal diameter equaling its altitude, and stout, slightly truncate apex having a diameter of
0.66 of its base. It is slightly deflected dorsally. The hypocone is similar in size and general
form to the epicone, tapers a trifle more gradually into the antapical process, which in our
specimen is conical, with a length of approximately 0.4 transdiameter and a basal diameter of
0.66 its length. It is deflected ventrally for about 10° from the axis. The antapex is broadly
rounded.

The girdle forms a descending left spiral displaced distally about 0.25 the total length of the
body, with slight overhang. The furrow is rounded, deeply impressed in its proximal part, less
so distally, and has no protuberant or overhanging lips. The anterior flagellar pore is at the
upper angle of the proximal end, and the flagellum traverses about 0.5 of the circumference.
The suleus could be traced for a short distance as a narrowing groove anterior to the girdle. It
passes posteriorly with a sigmoid flexure to about an equal distance beyond its junction with the
distal end of the girdle. The posterior flagellar pore lies midway between the two ends of the
girdle.

No surface markings could be found on the pellicle. The nucleus les near the center of the
midbody to the right and below the proximal end of the girdle. It contains numerous beaded
chromatin threads polarized to the left and anteriorly. It seems to be crowded to one side by
the large, opaque, dull greenish yellow mass enclosed in a vacuole, probably a food ball. Adjacent
to this are several highly refractive oil globules. A small sacklike pusule with pinkish contents
forms a diverticulum directed posteriorly from the anterior flagellar pore. A sulphine-yellow
sphere is found in the posterior part of the hypocone.

290 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The whole body is suffused with a primuline yellow tint fading in the antapical process to a
light chalcedony yellow.

The body is enclosed in a very thin and exceedingly transparent cyst wall which is closely
applied to the body, even sinking into the furrow of the girdle. About the apical and antapical
processes it is distended and is prolonged beyond each in finger-like processes of equal length,
about 0.66 that of the body. This distension indicates a difference in the osmotic properties or
capacities of the membrane in these regions or a localized permeability of the body permitting
greater exudation in these terminal surfaces.

Diuvenstons.—Length, of body 66+, of total cyst 137+; transdiameter, 33+.

OccuURRENCE.—Described from a single individual taken in a haul of a No.
25 silk net from 80 meters, 4 miles offshore at La Jolla, California, in the
California Current in surface temperature of 19°8 C on July 9, 1917. It was
again found July 23, in a haul 6 miles offshore in 80 meters to the surface and
a surface temperature of 20°8 C.

ComMPaARISONS.—This species bears a superficial resemblance to Gymnodinium
fusus Schutt (1895, pl. 24, fig. 79, pl. 25, fig. 81), vet differs from both the forms
which Schiitt has figured under this name, the first of which is a Gymnodinium,
the second we have placed in Gyrodinium as G. falcatwm nom. sp. noy. Our
species resembles G. falcatum (fig. CC, 11) in the presence of distinct apical
processes which are distinct from the midbody and blunt at the ends, features
which distinguish these two species from all other fusiform species of the genus.
There is a possibility that there might be some change in form incident upon
release from the cyst, vet such changes have not occurred in our material except
in one individual in which the body was filled with large food masses. This
was enlarged posteriorly but without change anteriorly. Schutt’s form shows
many yellow-ochre chromatophores which are totally lacking in our species.
It was also larger, measuring 122» as compared with 66, the length of our form.

Gyrodinium concentricum (Lebour)
Text figures EE, 1, 2

Spirodinium concentricum Lebour (19176), p. 194, fig. 11.

Under this name Miss Lebour has figured a Gyrodinium characterized by
concentric lines arranged around a certain point on the side or dorsal surface
of the body. The body is colorless with a shape and girdle arrangement like
G. obtusum Schutt. This is evidently a species of Gyrodinium parasitized by
a species of Amoebophrya Koppen. Forms parasitized by some member of this
genus have been observed in our own material and present the coiled appearance
shown in Lebour’s figure. This explanation seems to be borne out by her own
statements of the inconstancy in position of the spiral, the variations in size of
the organism and that it was of rare occurrence. Sufficient data are not given
to identify the Gyrodinium ; we, therefore, place it among the species of doubtful
status as undeterminable.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 291

Gyrodinium contortum (Schitt)
Text figure CC, 22

Gymnodinium contortum Sehiitt (1895), p. 11, pl. 21, fig. 67,..
Gymnodinium opimum Sehiitt (1895), pl. 21,.68b.
Spirodinium opimum, Lemmermann (1899), p. 360.

Diacnosis.—A large species with ovoidal body, its length 2.68 transdiameters
at the widest part; girdle a descending left spiral, displaced 1.4 transdiameters ;
sulcus extending from near the apex to the antapex ; surface striate ; color, yellow
ochre. Length, 134. Atlantic or Bay of Naples.

Description.—The body is long ovoidal, tapering anteriorly and rounded posteriorly where
it is widest in its posterior third, its length 2.68 transdiameters at the widest part. The epicone
exceeds the hypocone in length by 0.1 of its own length, but, owing to its narrower width, is not
greater in size. It is conical in shape (40°) with blunt apex. It has a length on the left and
right sides of 0.24 and 0.77 of the total length of the body. The hypocone is broader than the
epicone with a rounded antapex which is notched on the ventral face by the distal end of the
sulcus.

The girdle joins the sulcus at a distance from the apex of 0.24 of the total length of the body.
It turns posteriorly at an angle of 35° from the horizontal plane in its spiral course around the
body. decreasing the steepness of its course in the last quarter of its length, meeting the girdle
distally at an angle of about 20° from the horizontal. It is displaced 1.4 transdiameters at the
widest part of the body. The furrow is wide, 0.08 transdiameter in width, and deeply impressed.
The suleus begins below the apex and passes posteriorly with a strong left deflection, giving it a
torsion of about 0.5 transdiameter. It is enlarged near the antapex to about twice its width
anteriorly.

The nucleus is ellipsoidal and midventrally placed. Its chromatin contents are arranged in
coarse strands following its long axis. Its major and minor axes are 0.74 and 0.42 transdiameters
in length respectively. Numerous vacuoles of varying sizes are scattered through the cytoplasm.
In the peripheral zone is a layer of rodlets, radially arranged. The surface is striate with
equidistant, longitudinal striae.

Drivensions.—Length, 111 to 134#; transdiameter, 454 to 50”; axes of
nucleus, 37 and 21.

OccuRRENCE.—Figured by Schiitt (1895) from the collections of the
Plankton Expedition from the Atlantic or from the Bay of Naples. A single
individual was taken July 19, 1906, 1.5 miles off La Jolla, in a surface haul with
a No. 20 net. This individual was dark yellow ochre in color.

SynonyMy.—Schiitt (1895) figured as two distinct species two forms,
Gymnodinium contortum and G. opimum, which we have here placed as synony-
mous. Their size differs slightly, contortum having a length of 134” and a
width of 50” and opimum 111 and 45, a difference within ordinary species
variation. Both are ovoidal in outline, widest posteriorly (Schutt’s fig. 68),
pl. 21 (1895) of G. opimum is evidently oriented wrong end uppermost), with
the same or nearly the same relative proportions and surface striae as in his
G. contortum.

292 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

CoMPaRIsONS.—Gyrodinium contortum, in its wide displacement of the girdle
and its overhang, resulting from the torsion of the sulcus, leads onward in the
line of evolution to the next genus, Cochlodinium. The torsion of the intercing-
ular part of the sulcus in this species is greater than in G. ochraceum sp. nov.
(fig. DD. 17), though without the antapical loop of that species, which gives
its entire sulcus a slightly greater torsion than in G. contortum. It belongs in
this group of ochraceous striate species, including G. ochraceum sp. noy. and
G. fulvum sp. noy. (figs. DD, 9, 17), all of which appear to lack chromatophores.
It is clearly distinguishable from these by its proportions.

Gyrodinium corallinum sp. noy.
Plate 10, figure 117; text figure DD, 12

DraGcnosis.—A large species with asymmetrically biconical body, its length
1.96 transdiameters; girdle a premedian, descending left spiral, displaced 0.62
transdiameter; sulcus extends from girdle or near apex to antapex; surface
moderately striate; color, greenish yellow with scattered coral-red pigment.
Length, 1554. Pacific off La Jolla, California, July.

DescripTion.—The body is asymmetrically biconical, nearly subrhomboidal in shape, its
longest transdiameter slightly premedian, its length 1.96 transdiameters at the widest part. A
cross-section of the body is nearly circular. The hypocone far exceeds the epicone in size, its
length being greater by 0.21 of its own length. The epicone has the shape of a broad cone of
about 70° with blunt apex. It has a length on the left and right sides of 0.26 and 0.59 respec-
tively of the total length of the body. The sides of the epicone are nearly straight or sometimes
slightly coneave on the right side. The hypocone is elongate conical, of about 40°, with sides
somewhat more convex than those of the epicone. It has a length on the left and right sides of
the body of 0.72 and 0.42 respectively of the total length of the body. The blunt antapex is
slightly wider and more rotund than the apex.

The girdle is premedian in position for the greater part of its length. Its proximal end joins
the suleus at a distance from the apex of 0.26 of the total length of the body. It follows a
descending left spiral course around the body, the first 0.5 transdiameter of which is nearly in
a transverse direction, gradually steepening onward until it joins the suleus at a distance from
the apex of 0.59 of the total length of the body, and at an angle of about 55° with the longi-
tudinal plane of the body. Its distal end is displaced posteriorly about 0.62 transdiameter. The
furrow has a width of about 0.06 transdiameter, and is deeply impressed with smooth borders.
The suleus begins near the apex and extends posteriorly in an almost straight line to the antapex.
On the epicone it is narrow almost to invisibility in some individuals. In others, particularly
those having food masses present, it is wider, showing the evident correlation of the suleal area
and food ingestion. The anterior flagellar pore is found at the anterior junction of the girdle
and suleus, the posterior pore midway between the posterior junction and the antapex.

The nucleus is large, spherical and slightly premedian in position. It is differentiated into
two distinct parts. The outer, circular zone, which is about 0.1 of the total transdiameter of
the nucleus in width, is composed of pinkish vacuoles, elongated in optical section with the long
axis at right angles to the surface of the nucleus. Outside of these is a clear, double-contoured
membrane. The inner zone is apparently separated from the alveolar layer by a membrane or
a very thin, clear area. The central area is completely filled with chromatin granules without
evident linear arrangement. The axis of the nucleus is about 0.47 transdiameter in length.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 293

Small sacklike pusules open into each flagellar pore. The cytoplasm is clear and transparent
and greenish yellow in color. Small, green oil droplets, a few dark refractive granules, and a
number of large pink vacuoles were seattered through it. The surface is striate. On the epicone
the striae are about 20 in number across one face, and on the hypocone about 1.5 times as many.
The striae are blue green in color. Scattered along the line of striae are masses of coral-red fluid
pigment. On the epicone these are elongated, sometimes extending from the girdle to near the
apex in an unbroken line or they may be in shorter, thicker masses. On the hypocone they are
fewer in number, and more variable in size, usually minute and seattered scantily along the
striac, like beads on a string. Just underneath the pellicle are a number of large rounded masses
of pigment. These are found in both epicone and hypocone, but are more numerous and larger
in size in the epicone. Several of the elongated rodlike masses are found at the antapex. Some
individuals observed contained large bodies and many vacuoles, evidences of holozoic nutrition
in this species.

Dimenstons.—Length, 124-158; transdiameter, 52-80/; transdiameter of
nucleus, 30-40.

OccURRENCE.—T'wo specimens were taken July 9, 1917, with a No. 25 silk
net, 4 miles off La Jolla, California, in a haul from 80 meters to the surface
and in a surface temperature of 19°2 C. It was found again on July 11, in
approximately the same place and with the same apparatus.

Comparisons.—In its nuclear structure, color, and arrangement of pigment
this species closely resembles G. virgatwm (pl. 10, fig. 112; fig. DD, 21). In the
relative proportions of the body and girdle displacement, however, it shows
considerable differences. The posterior portion of G. virgatum is somewhat
distorted by the recent ejection of a food body, but this could hardly account
for the differences in size and proportion. The hypocone of G. corallinum is
more finely striate, its displacement of girdle in relation to the transdiameter
less, and its posterior flagellar pore much farther below the posterior junction
of girdle and sulcus than in G. virgatum.

Gyrodinium cornutum (Pouchet)
Text figure EE, 9

Gymnodinium spirale var. cornutwm Pouchet (1885a), p. 69, pl. 4, fig. 31.
Spirodinium cornutum, Lemmermann (1899), p. 359.
Not Gymnodinium cornutum Schiitt (1895), pl. 22, fig. 71 (= Gyrodinium schwetti

(Schiitt) ).

DraGnosis.—A medium sized species with spindle-shaped body, its length
2.8 transdiameters; girdle a descending left spiral, displaced about 1.21 trans-
diameters; sulcus apparently extending to the antapex; color, greenish. Length,
104, Atlantie off Concarneau, France, June.

Description.—The body is spindle-shaped, widest at the middle and tapering towards both
ends. its length 2.8 transdiameters at the widest part. The epicone is exceeded in size by the
hypocone, its length being 0.11 of its length less than that of the hypocone. The epicone is
conical (55°) with a narrow, blunt apex. Its length on the left and right sides is 0.24 and 0.67
of the total length of the body. The hypocone has a blunt antapex and is further marked off
by two protuberances on the ventral face which are probably the borders of the suleal region,

294 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The girdle begins at a distance from the apex of 0.24 of the total length of the body. It
passes around the body in a steep descending left spiral course, becoming displaced 0.67 trans-
diameters. The furrow has a width of about 0.08 transdiameter and is deeply impressed. The
sulcus is not figured by Pouchet (1885a), but evidently extends at least from the proximal end
of the girdle to the antapex. Its borders posteriorly are drawn out into projecting processes,
one of which extends slightly beyond the antapex.

The nucleus and other cytoplasmic inclusions are not figured and no reference is made by
Pouchet regarding these structures. The color of the organism, which he notes as similar to that
of G. spirale, is probably greenish.

Dimenstons.—Length, 104; transdiameter, 39v.

OccURRENCE.—Figured by Pouchet (1885a) from collections made in the
Atlantic off Conearneau, France, in June.

SynonyMy.—Originally described by Pouchet (1885@) as a distinct species
and also as a variety of Gymnodinium spirale. He wavered between these two
conceptions in his discussion, introducing both designations in his text and
inserting a query (?) after his varietal designations in his description of his
figure. Lemmermann (1899) transferred it to Spirodinium as a species of
that genus.

Gyrodinium crassum (Pouchet)
Text figure CC, 21

Gymnodinium crassum Pouchet (1885a), pp. 66-67, pl. 4, fig. 28; (1885b), pp. 528, 529,
pl. 26, fig. 2; (1887), p. 89; (1894), p. 169.

G. crassum, Biitsechli (1885), pp. 965, 971.

G. crassum, Schiitt (1895), p. 40.

Spirodinium crassum, Lemmermann (1899), p. 359.

S. crassum, Pavillard (1905), pp. 47, 80.

S. crassum, Paulsen (1908), p. 103, fig. 141.

S. crassum, Lebour (1917b), p. 195, fig. 12.

DraGnosis.—A large species with long ellipsoidal body, its length 2.54 trans-
diameters; girdle a descending left spiral, displaced 0.92 transdiameter ; sulcus
extending from girdle to antapex; surface striate; color, yellowish brown.
Length, 165". Atlantic, Concarneau, France, in October; Plymouth Sound,
England, in June; Arctic Ocean, Gulf of Lyons, October and November.

Description.—Body elongate ellipsoidal with irregular rounded apices, slightly wider poster-
iorly, its length 2.54 transdiameters at the widest part, which is about the middle of the hypocone.
The epicone exceeds the hypocone in length by about 0.18 of its own length. It is long, with its
sides subparallel to near the apex where they contract irregularly to the narrow, bluntly rounded
apex. Its length on the left and right sides is about 0.38 and 0.73 respectively of the total length
of the body. The hypocone is shghtly wider than the epicone, and is more rounded towards the
antapex, the left side of which is notched by the distal end of the suleus.

The girdle is posterior to the equatorial plane for about 0.75 of its length. It meets the
proximal end of the sulcus at a distance from the apex of 0.38 of the total length of the body.
It sweeps around the body in a descending left spiral, its distal end joining the suleus 0.73 of

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 295

the total length of the body from the apex, being displaced 0.89 transdiameter. The furrow is
relatively narrow, 0.06 transdiameter, and deeply impressed with recessed anterior lips and
rounded posterior border. The suleus begins at the proximal end of the girdle and extends
posteriorly to the antapex, as a narrow channel. Pores and flagella were not noted by Pouchet
(1885b).

The nucleus is ovoidal and situated near the center of the body, but is not definitely shown
in position in Pouchet’s figures (1885a, b). The cytoplasm is filled with large vacuoles with a
dark dense granular mass near its center. The surface is marked with broken (?) longitudinal
striae. The color is yellowish brown with a darker mass near the center.

Drvensions.—Lenegth, 120/ to 200; transdiameter, 60 to 65v.

OccuRRENCE.—Figured by Pouchet (1885a, b) from the Atlantic off Con-
carneau, France, from collections made in October and (1894) from the Arctic
Ocean near Spitzbergen. The other records of its appearance are as follows:
Lebour (1917b) from Plymouth Sound, England, in June. The form she de-
scribes is considerably smaller than Pouchet’s, having a length of only 75+.
Pavillard (1905) records it from the Gulf of Lyons in October and November.

SynonyMy.—Originally described from a single individual by Pouchet
(18852) as Gymnodinium crassum, and again in the same year (1885), pl. 26,
fig. 2) he figures another individual assigned to G. crassum which differs from
the first figure in the dimensions and the clear indication of a median longitu-
dinal furrow without spiral course. His earlier figure (see his pl. 4, fig. 28)
showed a lateral, furrow-like indentation on the left side (of the figure), which
might be interpreted as indicating a spiral course of about 0.3 turn on the part
of the longitudinal furrow. However, he speaks of this longitudinal furrow
as being slightly undulating without specifying the course of the furrow which
is hidden in the figure. The probabilities are that the notch does not represent
a furrow and that the two figures refer to the same species. Both figures are
inverted. Lemmermann (1899) and later Paulsen (1908) refer the species to
Spirodinium.

Comparisons.—The cytoplasmic structure of this species recalls that of
Gymnodinium dogieli and G. pachydermatum, without, however, having the
thickened periplast or ectoplasmic region of that species. The dark mass near
the center of the body is evidently formed of the dark, highly refractive granules
similar to those found in Gymnodinium, and which are probably the metabolic
products of holozoic nutrition.

Gyrodinium crassum is the largest species in Gyrodinium and significantly
is one with a northern distribution, and found in the cooler part of the year.
It is not close to any other species in the genus in proportions or structure.
The nearest one appears to be G. ochraceum sp. nov. (fig. DD, 17), but the color
of the latter is far more brilliant, its suleus has more displacement and torsion,
and the apices are different in the two species.

296 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Gyrodinium culeus sp. nov.

Plate 7, figure 77; text figure CC, 2

DraGgNnosis.—A medium sized species with ellipsoidal body, its length 1.71
transdiameters; girdle a submedian, descending left spiral, displaced 0.63 trans-
diameter; sulcus extending from apex to antapex; color, pearl grey with rose-
red pigment granules. Length, 65". Pacific off La Jolla, California, August.

DescripTioN.—The body is subellipsoidal in outline, widest posteriorly, with broad apices, its
length 1.71 transdiameters at the widest part, which is near the middle of the hypocone. The
hypocone exceeds the epicone in size, its length being nearly equal but its transdiameter slightly
greater than that of the epicone. The epicone is elongate hemispherical in shape, with symmet-
rically rounded sides. It is slightly notched at the apex by the proximal end of the suleus. The
right side widens somewhat behind the level of the anterior pore. It has a length on the left
and right sides of 0.32 and 0.68 respectively of the total length of the body. The hypocone is
elongate hemispherical in shape, slightly wider with sides more convex than those of the epicone.
The antapex is smoothly rounded without suleal notch.

The girdle is submedian in position. Its proximal end joins the suleus at a distance from
the apex of 0.32 of the total length of the body. It follows a descending left spiral course around
the body and meets the suleus at a distance from the apex of 0.68 of the total length of the body,
its displacement being 0.63 transdiameter. It has a width of about 0.06 transdiameter and is
deeply impressed wih smooth borders. The suleus begins in a slight enlargement at the apex
and extends posteriorly in an almost straight line to near the antapex. The anterior flagellar
pore opens at the proximal junction of the girdle and suleus, the posterior pore about one width
of the girdle below their posterior junction.

The nucleus is a broadly ellipsoidal body, filled with fine, moniliform chromatin strands with
a circular arrangement. It is found in the anterocentral part of the body. Its major and minor
axes are about 0.55 and 0.44 transdiameters in length respectively.

A small, sacklike pusule opens into the anterior flagellar pore. None was noticeable at the
posterior pore. The cytoplasm is finely granular and, in the individual figured, was densely
filled with large vacuoles containing a salmon-pink fluid. No other bodies were present. The
general color of the cytoplasm is a pearl grey, with a faint tinge of rose red. The latter color
was condensed into a group of rose-red granules at the antapex and another group near the left
margin of the body, immediately below the girdle. No striae or other surface markings could
be detected.

Dimensions.—Length, 654; transdiameter, 38; axes of nucleus, 21“ and 17+.

OcCURRENCE.—One individual was taken August 8, 1917, 4 miles off La Jolla,
California, in a haul from 80 meters to the surface and in a surface temperature
of 21°9 C.

Comparisons.—The rose-red color of this form is the same as that found in
Gymnodinium rubrum (pl. 8, fig. 86), G. rubricauda (pl. 8, fig. 88), G. lineatum
(pl. 1, fig. 2), and G. sulcatum (pl. 8, fig. 83). The only Gyrodinium presenting
the same coloring is G. rubricaudatum (pl. 10, fig. 116). Near it, however, is
the coral red of G. corallinum (pl. 10, fig. 117) and G. virgatum (pl. 10, fig. 112).

The only non-striate Gyrodinium approaching this species in size and pro-
portions is G. dorsum sp. nov. (fig. CC, 19), but this species differs from G.
culeus in having less displacement of the girdle, which is also farther posterior.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 297

Gyrodinium cuneatum nom. sp. nov.
Text figure CC, 17
Gymnodinium gracile, Pouchet (1885a), pp. 69-71, pl. 4, figs. 82, 33.

Draanosis.—A large species with obovate or cuneiform body, its length 1.72
transdiameters; girdle a descending left spiral, displaced 0.6 transdiameter ;
sulcus extending from apex to antapex; epicone striate; color, rose. Length,
100u. Atlantic off Concarneau, France.

Description.—The body is obovate or cuneiform in shape, widest anteriorly, its length 1.72
transdiameters at the widest part, which is at the girdle. The hypocone exceeds the epicone in
size, being nearly twice its length. The epicone has the shape of a broad, low cone of about 100°
with the apex slightly notched (by the anterior end of the suleus?). It has a length on the left
and right sides of 0.37 and 0.7 respectively of the total length of the body. The increase in
length is confined to the right side of the ventral surface where it is drawn out posteriorly in a
long slender point. The hypocone has an elongate campanulate shape, flaring at the region of
the girdle and symmetrically rounded posteriorly.

The girdle is premedian for most of its length, with a distance from the apex at its proximal
and distal ends of 0.37 and 0.7 respectively of the total length of the body, having a displacement
of 0.6 transdiameter. It passes around the body in a transverse plane for about 0.75 of the
circuit, turning posteriorly at a rapidly steepening angle which becomes about 15° with the
longitudinal plane, at its point of union with the suleus. The furrow has a width of about 0.06
transdiameter, and is deeply impressed with overhanging borders. The suleus probably begins
at the notch at the antapex and passes posteriorly as a slender, obscure trough in a nearly
straight line to the antapex. The longitudinal flagellum arises a short distance beyond the distal
junction of the girdle and suleus. The transverse flagellum is not figured by Pouchet (1885a).

The nucleus is ellipsoidal and located near the posterocentral part of the body. Its major
and minor axes are about 0.26 and 0.48 transdiameters respectively in length.

The central part of the cytoplasm is occupied by a mass of yellow-orange granules of varying
sizes, larger in the center and smaller peripherally. Large colorless vacuoles are present in the
epicone with a few in the antapical region. The general color of the body is a transparent rose
diffused through the cytoplasm. The surface of the epicone is marked by longitudinal striae
which fade out near the apex and girdle.

Dimenstons.—Length, 90-100; transdiameter, 58; axes of nucleus, 28 and
17p.

OccuRRENCE.—Figured by Pouchet (1885a) from the Atlantic off Conecar-
neau, Krance.

SynonymMy.—This form was figured by Pouchet as Gymnodinium gracile
Bergh. It differs, however, from that species in its lack of a differentiated
ectoplasm, absence of striae on the hypocone, and in the greater displacement
of its girdle. This latter feature removes it from Gymnodinium, and we, there-
fore, place it in Gyrodinium as G. cuneatum nom. sp. nov.

298 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Gyrodinium dorsum sp. nov.
Plate 7, figure 81; text figure CC, 19

Dracnosts.—A medium sized species with elongate ellipsoidal body, its length
1.85 transdiameters; girdle postmedian, a descending left spiral, displaced 0.43
transdiameter ; color, yellowish. Length, 72H. Pacific off La Jolla, California,
August.

Descrrption.—The body is elongate ellipsoidal with broad, rounded apices, nearly circular
in cross-section, its length 1.83 transdiameters at the widest part, which is at the girdle. The
epicone exceeds the hypocone in size, its length being greater by 0.31 of its own length. It is
elongate hemispherical in size with symmetrically rounded sides and broad apex. It has a length
on the left and right sides of 0.47 and 0.7 respectively of the total length of the body. The
hypocone is hemispherical posteriorly with its sides very slightly elongate anteriorly and flaring
around the anterior margin. It has a length on the left and right sides of 0.4 and 0.25 respee-
tively of the total length of the body.

The girdle is postmedian in position for the greater part of its length. Its proximal end joins
the suleus at a distance from the apex of about 0.47 of the total length of the body. It sweeps
around the body in a descending left spiral with its distal end meeting the suleus at a distance
from the apex of 0.7 of the total length of the body. The furrow has a width of 0.06 trans-
diameter, and is rather deeply impressed with smooth borders. The suleus extends from near
the apex to near the antapex in a slightly sinuous course. The furrow is deep and varies some-
what in width throughout its course. The anterior flagellar pore opens at the anterior junction
of the girdle and suleus, the posterior pore slightly posterior to the midpoint between the distal
junction and the antapex.

The nucleus is spherical and is located in the posterior half of the body. It is densely filled
with chromatin threads. Its axis is about 0.66 transdiameter in length.

A large sacklike pusule opens into each flagellar pore. The cytoplasm is finely granular. <A
large food mass, olive buff in color, occupied a position above the nucleus. Scattered through
the peripheral layer of cytoplasm were numerous blue-green oil drops. The general color is
aniline yellow mixed with grey and shading into buckthorn brown at both apices.

Dimenstons.—Length, 72; transdiameter, 39; axis of nucleus, 25z.

OccuRRENCE.—A single individual was taken August 21, 1917, 5 miles off
La Jolla, California, in a haul from 83 meters to the surface and in a surface
temperature of 21°9 C.

SynonyMy.—Pouchet’s form (1883), Gymnodinium spirale var. C, is prob-
ably the same as our species. It is somewhat larger, 1194 as compared with
72 in ours, but this is not too great for variations within the species. The
girdle is postmedian and its displacement is about the same as in Gyrodinium
dorsum. Its nucleus is spheroidal and in the plane of the posterior junction of
the girdle and sulcus. It differs greatly from G. spirale, both in the size and
shape of body and its lack of surface striae.

CoMPARISONS.—In only two other species of Gyrodinium has the girdle
become posteriorly located, G. crassum (fig. CC, 21), in which only a small
portion is anterior to the midplane, and G. glaucum (fig. DD, 16), in which the
hypocone is a relatively small part of the body.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 299

Gyrodinium falcatum nom. sp. nov.
Text figure CC, 11
Gymnodinium fusus Schiitt (1895), in part, including only fig. 81, pl. 25.

DracNnosts.—A large species with irregular, spindle-shaped body, its length
1.87 transdiameters; girdle submedian, a descending left spiral, displaced 0.39
transdiameter ; sulcus short on both hypocone and epicone; yellow ochre chro-
matophores. Length, 1217. Atlantic (?) or Bay of Naples.

Description.—The body is irregularly spindle-shaped, coneave dorsally, nearly straight ven-
trally, its dorsoventral and transverse diameters subequal, its length 1.87 transdiameters at the
widest part. It is broadly rounded in the middle, and contracted into narrower processes at
both ends. The epicone is slightly larger than the hypocone, its length being greater by 0.11 of
its own length. It is roughly subconical in shape, rotund posteriorly, deeply contracted midway
between the girdle and the apex, forming an irregular lobe anteriorly with convex sides with a
width of 0.41 transdiameter and a truneate apex. It is somewhat asymmetrical with the anterior
lobe shghtly deflected to the right. It has a length on the left and right sides of 0.41 and 0.62
respectively of the total length of the body. The hypocone is less irregular than the epicone,
rotund anteriorly with the posterior lobe shorter and the antapex more rounded than in the
epicone.

The girdle is submedian in position, its proximal end joining the suleus at a distance from
the apex of 0.41 and its distal end 0.62 respectively of the total length of the body. It sweeps
around the body in a descending left spiral course, displaced posteriorly 0.39 transdiameter.
The furrow has a width of about 0.06 transdiameter, and is deeply impressed with smoothly
rounded borders. The sulcus is short on both epicone and hypocone, is deeply impressed in the
intercingular area, soon fading out towards both apices. The flagella and pores were not figured
by Schitt (1895).

The body is completely filled with stout rodlike, yellow ochre chromatophores and spheroidal
bodies closely crowded together. Nucleus and pusules were not figured by Schiitt. The pellicle
is double contoured. The organism was surrounded by a cyst which conformed to the shape of
the body but was somewhat larger in size.

Dimenstons.—Length, 121/; transdiameter, 65; length of cyst, 175p.

OccuRRENCE.—Figured by Schiitt (1895) from material collected by the
Plankton Expedition, presumably from the Atlantic or from the Bay of Naples.

SynonyMy.—Schiitt (1895) on his plate 24, figure 79 (our text figure X, 5),
portrays Gymnodinium fusus, a form which is evidently a true Gymnodinium.
On his plate 25, figure 81 (our text fig. CC, 11), he gives the same name to
another organism which has the Gyrodinium type of girdle, with approximately
the same size as the first form. While the comparative length and breadth may
vary considerably in the species or even in the same individual, corresponding
to different states of contraction and expansion, yet this does not affect the
displacement of the girdle, the intercingular area remaining nearly constant.
The girdle displacement in his second figure (our text fig. CC, 11) is greater
than one-fifth the total length of the body; we therefore place it in the genus
Gyrodinium as G. falcatum. Schiitt’s figure 81., plate 25, is inverted, showing
a reversed relation to that in his figures 81: and 81... The absence of the flagella

300 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

makes the orientation of this species a tentative one only. We have, however,
followed, in our description, the orientation given in Schiitt’s figure 81.

Comparisons.—This is one of the four species of Gyrodinium showing the
presence of chromatophores, the other species being G. pusillum (Schilling),
G. melo sp. nov., and G. foliaceum sp. nov. (figs. CC, 3, 9,18). The yellow-ochre
chromatophores of this species are similar to but smaller and more numerous
than those in Gymnodinium fusus. The presence of small globules or vacuoles
throughout the cytoplasm suggest holozoic nutrition, as these are probably
products of metabolism. In its contracted apices this species is unique in
Gyrodinium.

Gyrodinium fissum (Levander)
Plate 9, figure 95; text figure DD, 8

Gymnodinium spirale var. D Pouchet (1883), p. 448, fig. K.

G. fissum Levander (1894a), pp. 43-50, pl. 2, figs. 5-20; (1894b), p. 210; (1900), p. 41;
(1901a), pp. 8, 13, 18, 19; (1901b), p. 6; (1913), p. 36 (as Spirediniwm fissum).

Spirodinium fissum, Lemmermann (1900), p. 116; (1901), p. 359; (1905a), p. 20.

S. fissum, Paulsen (1908), p. 101, fig. 139.

Gymnodinium fissum, Ostenfeld (1908), pp. 136, 162, 210, 213.

Spirodinium fissum, Lebour (1917b), p. 193.

Dracnosts.—A small species with subovoidal or ellipsoidal body, its length
1.79 transdiameters; girdle a descending left spiral displaced 0.31 transdiam-
eter: sulcus extending from apex to antapex; surface finely striate; color, pale
Veronese green. Length, 46. Pacific off La Jolla, California, July, August;
Atlantie off Concarneau, France; Gulf of Finland.

DerscripTION.—The shape of the body is subovoidal to ellipsoidal, somewhat metabolic poster-
iorly, its length 1.79 transdiameters at the widest part, which is at the girdle. A cross-section
of the body is nearly circular in outline. It is rounded at both apices, but usually more tapering
anteriorly or the two may be subequal. The epicone exceeds the hypocone in size, its length being
greater by 0.22 of its own length. The epicone is rounded dome-shaped, somewhat less than a
hemisphere, with broad, symmetrically rounded apex. The relative length and width vary
considerably in different individuals; when well extended it is subeconical with slightly rotund
sides. As the contraction of the body increases the convexity of the sides becomes more pro-
nounced and the altitude decreases. It has an average length on the left and right sides of 0.4
and 0.67 respectively of the total length of the body. The hypocone is slightly broader than the
epicone with broad, rounded antapex, or it may be equal or slightly narrower with the right side
of the antapex extending farther posteriorly than the left side.

The girdle is submedian in position, its proximal end joining the suleus at a distance from
the apex of 0.4 of the total length of the body. It forms a descending left spiral with its distal
end joining the sulcus at a distance from the apex of 0.67 of the total length of the body, its
displacement being about 0.31 transdiameter. The greater part of this displacement takes place
in the distal fourth of the girdle where it follows a course at an angle of about 45° with the
median longitudinal plane. The first part of its course is in a nearly transverse direction around
the body. The furrow has a width of about 0.08 transdiameter and is deeply impressed with
smooth borders, of which the anterior one is deeply undercut. Both borders are usually raised

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 301

somewhat above the surface of the body. The suleus begins near the right side of the apex and
extends posteriorly in a slightly sinuous line to the antapex. The anterior flagellar pore opens
at the proximal junction of the girdle and sulcus, the posterior pore about one width of the
girdle below the distal junction.

The nucleus is a spheroidal body filled with coarse chromatin strands. It is found near the
center or sometimes in the anterior part of the body. Its axis is about 0.5 transdiameter in
length.

A small sacklike pusule opens into each flagellar pore; sometimes one or both may be
temporarily absent. In one individual the anterior pusule was located near the center of the
body and connected with the anterior pore by a slender canal. The cytoplasm is coarsely
granular, often vacuolate in structure with few to many long, greenish rodlets radially arranged.
The peripheral zone contains a layer of much smaller, radially arranged, blue-green rodlets
placed at right angles to the surface. They appear between the surface striae in surface view as
minute, blue-green, circular granules. The surface is longitudinally striate with equidistant,
blue-green lines, about 24 across the ventral face of the epicone, and twice as many on the
hypocone. The general color of the organism is pale Veronese green with, rarely, a tinge of
coral red in the epicone.

Druensions.—Length, 46-57; transdiameter, 29-384; axis of nucleus,
13-17.

OccURRENCE.—This was first observed in two surface hauls made July 18
and 19, 1906, one 0.75 mile, the other 1.5 miles off La Jolla, California, with a
No. 20 net, and in a surface temperature of 21°9 C. On July 12 and 20, 1917,
it was taken in two hauls made with a No. 25 net, 6 miles offshore, from 80
meters to the surface and in surface temperatures of 20°6 C and 21°1 C respec-
tively. It was again observed August 8, in a haul 4 miles offshore, from 80
meters to the surface and in a surface temperature of 22°5 C.

Other records of its occurrence are as follows: Pouchet (1883) from the
Atlantie off Conearneau, France; Levander (1894a-1913), from the Gulf of
Finland near Helsingfors, Finland; Ostenfeld (1908), from the Aral Sea in
May, in surface temperature ranging from 17-7 C to 25°6 C, and Lebour
(1917b), from Plymouth Sound, England, in August and September.

SynonyMy.—This was first figured by Levander (1894a) as Gymnodinium
fissum and was later changed by Lemmermann (1900) to Spirodinium fissum.
In 1908 Paulsen placed with it as synonymous a form figured by Pouchet in
1883 as Gymnodinium spirale var. D. Ostenfeld (1908) records a species from
the Aral Sea as Spirodiniwm fissum Levander with a question mark, stating that
he was unable to identify it definitely as Levander’s species. His observations
were limited entirely to preserved material, and these forms very rarely with-
stand contact with a fixing fluid. Miss Lebour’s (1917b) form from Plymouth
Sound, England, is also doubtfully allocated. No figure or description is given
save that it is yellow in color with a peculiar dorsoventral flattening. In all
of our material the color was green and the body circular or nearly so in cross-
section. In Levander’s (1894@) description the color is green and the body
rounded in vertical view. He observed one individual with a slight dorsoventral
compression of the body.

302 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Comparisons.—Levander (1894«) describes the long greenish rodlets in his
figures as chromatophores. Such structures are frequently met with in the
Gymnodiniidae, as in Gymnodinium dogieli (pl. 3, fig. 34) and G. pachyder-
matum (pl. 8, fig. 32), and, with a shorter length, in many others. These are
probably metabolic in origin. On the dissolution of the cytoplasm they dis-
appear, as do fluid-filled vacuoles, and our own observations lead us to believe
that such is their structure, and that their function is concerned with the
metabolism of the cell in other relations than as chromatophores.

Gyrodinium flavescens sp. noy.
Plate 4, figure 39; text figure CC, 16

Dracnosis.—A small species with slightly asymmetrical, subovoidal body,
its length 1.85 transdiameters; girdle a descending left spiral, displaced 0.81
transdiameter, with overhang of about 0.4 transdiameter ; sulcus extending from
near apex to antapex, with torsion of 0.4 transdiameter; color, aniline yellow.
Length, 50. Pacific off La Jolla, California, August.

DescripTion.—The body is subovoidal and somewhat asymmetrical, its left dorsal side being
convex and the right ventral slightly concave. In cross-section the body is nearly circular. It
is widest posteriorly and its length is 1.85 transdiameters at the widest part. The length of the
epicone exceeds that of the hypocone by 0.25 of itself. The epicone is convex on the right side
and slightly concave on the left side with broad, rounded apex. It has a length on the left and
right sides of 0.36 and 0.8 respectively of the total length of the body. The hypocone is hemi-
spherical in shape, somewhat wider than the epicone and slightly notehed by the distal end of
the sulcus.

The proximal end of the girdle joins the sulcus at a distance from the apex of 0.36 of the
total length of the body. It passes around the body in a descending left spiral, meeting the
suleus at 0.8 of the total length of the body from the apex, with a displacement of 0.81 trans-
diameter and an overhang of about 0.4 transdiameter. The furrow has a width of about 0.09
transdiameter and is deeply impressed, with smooth, rounded borders. The suleus begins mid-
way between the anterior flagellar pore and the apex. It extends posteriorly in a sigmoid curve
with a torsion of about 0.35 to the antapex. Its width is about half that of the girdle, becoming
narrower in front of the anterior flagellar pore and beyond the posterior pore. The anterior
flagellar pore opens at the anterior junction of the girdle and sulcus, the posterior pore near the
antapex.

The nucleus is a long, sausage-shaped body found in the left side. Its unusual length may,
perhaps, be due to the oncoming of division. It was filled with long, moniliform chromatin
strands lying in its long axis. Its-axes were 1.3 and 0.3 transdiameters in length respectively.

The cytoplasm is coarsely granular, with numerous, minute, blue-green oil droplets scattered
through its peripheral zone. Several yellowish citrine-colored bodies were present, probably food
masses. The general color of the organism is aniline yellow shading to buckthorn brown, diffused
throughout the cytoplasm. Minute, dark refractive granules are also abundant. No striae or
other surface markings could be detected. A thin-walled, hyaline cyst, somewhat larger than
the body, enclosed it.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 303

Drvensions.—Length, 504; transdiameter, 26; axes of nucleus, 36 and 9v.

OccURRENCE.—A single individual was taken August 15, 1917, with a No. 25
silk net, 0.75 mile off La Jolla, California, in a haul from 80 meters to the surface
and in a surface temperature of 21°9 C,

CoMPARISONS.—This species, in the torsion of the girdle, foreshadows the
Cochlodinium type of furrow arrangement. The overhang, however, is still
considerably less than in that genus. There is no non-striate species of
Gyrodinium which approaches it in proportions.

Gyrodinium flavidum sp. nov.
Plate 7, figure 73; text figure CC, 20

Dracnosis.—A large species with asymmetrical, rotund ellipsoidal body, its
length 1.5 transdiameters; girdle a descending left spiral, displaced 0.54 trans-
diameter ; sulcus extends from apex to antapex; color, ochraceous grey. Length,
102. Pacific off La Jolla, California, August.

DeEscripTION.—The body is robust ellipsoidal, asymmetrical with the ventral face more convex
than the dorsal face, its length 1.5 transdiameters at the widest part. A cross-section of the
body is nearly cireular in outline. The hypocone exceeds the epicone in size, its length being
ereater by 0.25 of its own length. The epicone is asymmetrical, the left side being raised in a
high shoulder effect, throwing the apex, a knoblike extension, somewhat to the right. It has a
length on the left and right sides of 0.16 and 0.51 respectively of the total length of the body.
The hypocone is also asymmetrical, but less so than the epicone. Its sides are rounded and the
antapex forms a short knoblike projection. It has a length on the left and right sides of 0.76
and 0.41 respectively of the total length of the body. The parts of both epicone and hypocone
bordering the girdle are drawn out into wide, shelflike ridges.

The girdle is premedian in position for most of its course. Its proximal end joins the sulcus
at a distance from the apex of 0.16 of the total length of the body. It sweeps around the body
in a descending left spiral course to meet the sulcus at a distance from the apex of 0.51 of the
total length of the body. The furrow has a width of about 0.07 transdiameter, and is deeply
impressed, with borders raised somewhat above the surrounding surface of the body. The sulcus
is a narrow trough extending in a slightly sinuous line from near the apex to near the antapex.
The anterior flagellar pore opens at the anterior junction of the girdle and suleus, the posterior
pore midway between the distal junction and the antapex.

The nucleus is a spheroidal body found in the left side, slightly anterior to the equatorial
plane. It is filled with moniliform, chromatin strands spirally arranged. Its axis is about 0.35
transdiameter in length.

The eytoplasm is coarsely granular, especially near the surface, giving the organism a mottled
appearance. It was filled with large vacuoles of the same color as the surrounding cytoplasm, a
pearl grey. Scattered throughout the cytoplasm but becoming much denser at the apices are
minute granules of ochraceous orange and near the surface green oil droplets. Nutrition is
evidently holozoic, as the cytoplasmic inclusions are probably the products of metabolism. A
small sacklike pusule opens into the posterior flagellar pore. In other individuals one was
present at the anterior pore also. No striae were detected on the surface.

304 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Divenstons.—Length, 102-118-; transdiameter, 58-68; axis of nucleus, 25.

OccURRENCE.—Two individuals were taken August 21, 1917, with a No. 25
silk net, 5 miles off La Jolla, California, in a haul from 63 meters to the surface
and in a surface temperature of 21°9 C.

Comparisons.—In the outline of the body and the arrangement of girdle
and sulcus this species resembles G. truncus sp. noy. (fig. DD, 4). Its lack of
surface striae, however, differentiates it from that species and places it im the
subgenus Laevigella. It is also different in its relatively shorter intercingular
sulcus and its differentiated apical point. It is the most rotund representative
in the subgenus Gyrodinium.

Gyrodinium foliaceum nom. sp. noy.
Text figure CC, 18

Gymnodinium viride Schiitt (1895), pl. 26, fig. 88.

Diaanosts.—A small species with rotund ellipsoidal body, its length 1.2
transdiameters; girdle a descending left spiral, displaced 0.3 transdiameter ;
sulcus extending from girdle to antapex; green chromatophores. Length, 50+.
Atlantic or Bay of Naples.

Description.—The body is stout ellipsoidal, broadly rounded at both ends, its length 1.2
transdiameters at the widest part. The hypocone exceeds the epicone in length by about 0.15
of its own length. The epicone is subhemispherical with broad apex or the apex may be marked
off by a slight pointed projection. It has a length on the left and right sides of about 0.18 and
0.54 respectively of the total length of the body. The hypocone is broad and rounded, somewhat
less symmetrical than the epicone, and without suleal notch.

The girdle joins the suleus proximally about 0.18 of the total length of the body from the
apex. It sweeps around the body in a descending left spiral course which becomes displaced
posteriorly 0.3 transdiameter. The furrow is wide, 0.09 transdiameter, and deeply impressed with
overhanging borders. The flagella and pores were not indicated by Schiitt (1895). The sulcus
begins at the girdle or it may arise at the apex. It extends posteriorly to the antapex in a
sinuous line, but with no resulting torsion.

The nucleus is an ellipsoidal body in the posterior part. Its major and minor axes are 0.4
and 0.26 transdiameter in length respectively. A small sacklike pusule is present in the anterior
part of the body connected with the region of the anterior pore by a slender canal. A few large,
clear vacuoles are usually found in the cytoplasm, particularly in the epicone. Large, irregularly
shaped, leaflike green chromatophores are found, sometimes near the middle of the body, in other
ceases filling the peripheral zone over the entire body.

Divensions.—Length, 50; transdiameter, 42; axes of nucleus, 17 and 11+.

OccuRRENCE.—Figured by Schutt (1895) from collections made by the
Plankton Expedition, presumably from the Atlantic or from the Bay of Naples.

SynonyMy.—This form was described by Schutt (1895) as Gymnodinium
viride sp. nov. without knowing that this name had been used previously by
Penard (1891) for a different species from fresh water. We therefore propose
the new name foliaceum for it, and, by reason of its girdle, transfer it to the
genus Gyrodinium.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 305

Compartsons.—This species is close to Gyrodinium melo sp. noy. (fig. CC, 9),
but is smaller, stouter, with less of an apical point, less displacement of girdle
and torsion of sulcus with no overhang. The presence of chromatophores differ-
entiates it definitely from Gyrodinium ovoideum sp. nov. (fig. CC, 6), a larger
species without apical point but with about the same proportions.

Gyrodinium fucorum ( Kiister)
Text figure EH, 3

Gymnodinium fucorum Wiister (1908), pp. 852-356, figs. 1-4.
G. fucorum, Kofoid (1909), p. 246.

G. fucorum, Entz (1910), p. 161.

G. fucorum, Pavillard (1910), p. 536.

G. fucorum, Jollos (1910), pp. 181-193, pls. 7, 8.

G. fucorum, Giinther (1911), p. 8.

1. fucorum, Hartmann (1911), p. 16, fig. 4.

G. fucorum, Senn (1911), p. 639.

lon)

DescripTion.—A small species with rotund ellipsoidal body and broad apices, its length 1.33
transdiameters at the widest part; the girdle a descending left spiral, its relations to the sulcus
unknown. The epicone exceeds the hypocone in size. The color is pale yellow. Kiister’s (1908)
outline figures give the outline only of the cell, omitting all cell contents.

Divenstons.—Length, 28-85; transdiameter, 60-65.

OccuRRENCE.—This was figured by Kiister (1908) from the North Sea off
Helgoland, Germany. He was able to keep it in cultures of sea water in the
laboratory for six months.

SynonyMy.—Under the name Gymnodinium fucorum Kuster (1908) has
figured a form with a spiral girdle which evidently belongs to Gyrodinium.
His figures and diagnosis, however, are entirely inadequate to establish its
species characters, giving as he does the merest outline of the body and omitting
the full course of the girdle and its relations with the sulcus.

Jollos in 1910 published the results of his studies of the same material, which
he obtained from Kiister. Unfortunately he does not add to our knowledge of
the species characters of this form beyond stating that the girdle forms a steep
spiral. This character would remove it from Gymnodinium, where he leaves it,
but is sufficient only to locate it in the genus Gyrodinium. He describes division
which takes place within the cyst and results in four- or eight-celled stages
(Kiister, 1908). He also figures swarm spores, but does not show any con-
necting link between them and the dividing Gymnodinium. The later devel-
opment of the swarm spores was not followed. It is possible that he is here
confusing two entirely different organisms. His figures 30-41, plate 8, are
those of a small flagellate belonging to Bodo or Prowazekia, having a nucleus
with a central karyosome, a parabasal body or large blepharoplast and two
unequal flagella, one of them trailing. This divides by a simple mitosis with
a small number of chromosomes, unlike the type of mitosis found in Gymno-
dinium. There appear, therefore, fundamental differences between his two

306 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

groups of organisms too great to suggest any close relationship between them.
The entire lack of any suggestive links between the two groups would tend to
confirm our supposition that these are separate and distinct organisms. In
view of the lack of definite species characters both in Kiister’s description and
in that of Jollos we place this form among the species incertae sedis until it has
been reinvestigated.

Gyrodinium fulvum sp. nov.
Plate 7, figure 70; text figure DD, 9

DraGnosis.—A small species with ovoidal body with pointed apex, its length
1.87 transdiameters; girdle a descending left spiral with slight overhang and
displacement of 0.9 transdiameter; sulcus extending from girdle to antapex;
surface unevenly striate; color, yellow ochre. Length, 62+. Pacific off La Jolla,
California, July.

Description.—The body is ovoidal, rounded posteriorly, tapering abruptly anteriorly to a
point, its length 1.87 transdiameters at the widest part below the girdle. In cross-section the
body is nearly circular. The epicone and hypocone are subequal in size, though the greatest
length of the epicone is about 0.32 greater than that of the hypocone. Its transdiameter is
somewhat less. The epicone is broad and rotund posteriorly, tapering anteriorly to a slender,
pointed apex nearly 2 girdle widths in length. It has a length on the left and right sides of
0.36 and 0.85 respectively of the total length of the body. The hypocone is elongate, subhemi-
spherical with the antapex slightly notched ventrally by the distal end of the suleus. It has a
length on the left and right sides of about 0.59 and 0.19 respectively of the total length of the
body.

The preximal end of the girdle joins the suleus at a distance from the apex of 0.36 of the
total length of the body. It follows a descending left spiral course around the body, its distal
end meeting the sulcus at a distance from the apex of 0.85 of the total length of the body. Its
displacement is about 0.9 transdiameter with an overhang of about 0.2 transdiameter. It has a
width of about 0.07 transdiameter and is deeply impressed, undercutting its anterior border and
smoothly rounding out to the posterior one. The sulcus extends from the girdle to the antapex
in a slight sigmoid curve. Its width is nearly equal to that of the girdle. The anterior flagellar
pore opens at the proximal junction of the girdle and sulcus, the posterior pore near the antapex.

The nucleus is a spheroidal body filled with loose chromatin strands. It is located near the
center of the body. Its axis is about 0.48 transdiameter in length.

The pusule of the individual figured shows a rather unusual development. It consists of a
large, globular vesicle nearly as large as the nucleus in the posterior part of the body, connected
with the anterior flagellar pore by a long, slender canal. No pusule was present at the posterior
pore. The cytoplasm is coarsely granular. In the peripheral zone are numerous small spherules,
probably pigment, yellow ochre in color, with a few larger, greenish yellow bodies near the center
of the body. The cytoplasm is pearl grey in color. The surface of the body is striate, with the
number of lines on the hypocone about twice that on the epicone where there are about 22 across
the ventral face. The latter differ also in that every other line is slightly heavier and broader
than the intermediate lines.

Divensions.—Length, 62; transdiameter, 334; axis of nucleus, 16.

OccuRRENCE.—This was taken July 5, 1917, in a haul 6 miles off La Jolla,
California, from 80 meters to the surface and in a surface temperature of
21°9 C.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 307

Compartsons.—The small yellow-ochre spherule found in this species is
probably pigment similar to that present in G. ochraceum (pl. 7, fig. 76). It
did not show the same motility, but continued observation may establish its
similarity in that respect also. It differs from G. ochracewm in its type of
surface striae and in the smaller degree of torsion of the suleus, with 0.1 as
compared with 0.5 turns about the body. This species has the most highly
developed apical point in the genus except for those of G. fusiforme nom. sp.
noy. and G. lachryma (Meunier).

Gyrodinium fusiforme nom. sp. nov.
Text figures EE, 4, 8

Spirodinium fusus Meunier (1910), p. 63, pl. 14, figs. 23-26.
Not Gyrodinium falcatum nom. sp. nov. (= Gymnodinium fusus Schiitt (1895) in part).

Draenosis.—A small species with slender fusiform body, its length 3.7 trans-
diameters; girdle a descending left spiral, displaced 1.4 transdiameters; sulcus
-not determined. Length, 74+. Arctic Ocean.

DescripTion.—The body is slender fusiform, tapering to a sharp point at both apices, widest
in the middle, its length 3.7 transdiameters at the widest part. The epicone and hypocone are
subequal. The epicone is slender conical, about 30° anteriorly, shghtly broader posteriorly, with
a slender, acuminate apex. It has a length on the left and right sides of 0.29 and 0.71 respectively
of the total length of the body. The hypocone is also slender conical, with a long attenuate
antapex in the type figure (fig. EE, 4), somewhat shorter and blunter in a second specimen
(fig. EE, 8).

The girdle is a descending left spiral with a distance from the apex at its proximal and distal
ends of 0.29 and 0.71 transdiameters respectively. The furrow is not distinctly marked off in
Meunier’s figures, but it seems to have a width of about 0.18 transdiameter, and is shallow with
rounded borders. The suleus is imperfectly represented in the figures.

The nucleus is an ellipsoidal body filled with moniliform chromatin strands and lying in the
central or anterior part of the body. Its major and minor axes are 0.8 and 0.5 transdiameters
respectively.

Immediately posterior to the nucleus is a large vacuole. The peripheral zone of cytoplasm is
filled with short rodlets apparently arranged at right angles to the surface.

Dimensions.—Length, 74; transdiameter, 20; axes of nucleus, 16 and 10z.

OccuRRENCE.—This species was figured by Meunier (1910) from material
collected by the Duke of Orleans’s Arctic Expedition of 1907 in the Arctic
Ocean near Nova Zembla.

SynonyMy.—Meunier (1910) described his species as Spirodinium fusus.
This name was preoccupied by Gymnodinium fusus Schutt (1895), under which
designation two different forms were figured, one a Gymnodinium, G. fusus
Schiitt, and the other a Gyrodinium, G. falcatum nom. sp. nov., which we have
separated from Schiitt’s species. We therefore change the specific name of
Meunier’s form to fusiforme, on the ground that the specific name fusus was
once applied to a species which is now included within Gyrodinium (now G.
falcatum).

308 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Gyrodinium glaucum (Lebour)
Plate 9, figure 94; text figure DD, 16
Spirodinium glaucum Lebour (19176), p. 196, fig. 13.

DtaGnosis.—A small species with broadly fusiform body with abruptly con-
tracted apices, length 2.46 transdiameters; girdle far posterior, a descending
left spiral. displaced 0.26 of the total length; suleus extending from the girdle
to the antapex; color, greyish green. Length, 404. Pacific off La Jolla,
California, July; Plymouth Sound, England, May to October.

DescripTION.—This is a small species with fusiform body which tapers abruptly at both
apices, nearly circular in cross-section, its length 2.46 transdiameters at the widest part. The
girdle is placed far posteriorly, making the epicone occupy the larger portion of the body. The
epicone has a length on the left of 0.67 and on the right of the suleus of 0.9 of the total length of
the body. The left side is more convex than the right. The apex is pointed and flexed to the
left with a resulting rounding up of the right side. The hypocone is very short and rounded,
abruptly tapering to the antapex, which is pointed and slightly excavated on the left side by the
distal end of the suleus.

The junction of the girdle and sulcus occurs at about 0.67 of the total length of the body
from the apex. It passes around the body in a descending left spiral course and becomes dis-
placed posteriorly on the right side about 0.64 transdiameter, of which the greater part occurs
in the last third of its course. On the left side the girdle is wide, about 0.1 transdiameter, and
in the last fourth of its course it narrows until at its distal end it is about 0.3 of its width at its
beginning. It lies in a deep depression with smooth overhanging sides. The anterior flagellar
pore is located at the proximal junction of the girdle and suleus, the posterior pore at the
distal one.

The suleus is nearly straight, invading the epicone for a short distance anterior to the
proximal end of the girdle and extending posteriorly to the antapex. It is relatively wide at
its anterior end and becomes narrow near the antapex.

The nucleus is large and is located in the epicone. It is nearly spheroidal in outline with an
axis of about 0.76 transdiameter. It is filled with moniliform chromatin strands lying obliquely
to the longitudinal plane of the body.

The cytoplasm is clear and hyaline, pale greenish yellow in color. It is nearly filled with
hyaline spherical granules, oil droplets and refractive bodies. There are also present 4 to 5
long, slender, tapering, yellowish green rodlets, about 0.5—-0.66 of the total length of the body in
length. These are parallel and are arranged longitudinally near the periphery of the body.
They are probably products of metabolism, nutrition being holozoic. The surface is sparsely
striate with longitudinal, equidistant striae, about 10 across the ventral face.

Drrenstons.—Leneth, 40+; transdiameter, 16; nucleus, 12 and 13.

OccURRENCE.—This was figured by Lebour (1917b) from Plymouth Sound,
England, where it was present from May to October. A single individual of
this species was met with July 17, 1906, in a surface haul taken with a No. 8
net, 1.5 miles offshore, at San Diego, California, and in a surface temperature
of 21°9 C.

Activities.—The specimen under observation was restless, in constant
motion, usually moving in a flat, anticlockwise spiral direction with a radius
not to exceed twice its own length. The ventral surface was usually kept

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 309

uppermost with no rotation on the axis of the body. Occasionally there was a
spasmodic rotation of the body in an anticlockwise spiral, rarely in the reverse
direction, on its main axis. Not infrequently the organism would rise from
the substrate and turn a somersault backward from the previous direction of
progress and then resume the spiral gyrations.

Synonymy.—In Miss Lebour’s figures she gives as surface striae what seems
to correspond to the long, slender rodlets in our form. In her figure, 13), these
pass through the girdle, a condition never found in surface striae which termi-
nate at or near the margins of the girdle. In her figures the anterior end of
the body is occupied by a large, vellow mass, which is usually though not always
present, and the nucleus is posteriorly placed. This large food mass (?) was
absent in our example with the nucleus anterior and the cytoplasm filled with
small spherules. These differences are not great enough to separate the two
forms.

CoMPARISONS.—This species shows the greatest extreme in the relative pro-
portions of epicone and hypocone, the latter being comparatively minute. The
general tendeney from Amphidinium, with its relatively minute epicone, up
through Gymnodinium and Gyrodinium, has been towards an equalization of
the two parts of the body with a slight leaning towards a greater size in the
hypoecone. These conditions are reversed in G. glaucum, as also to a much
smaller extent in G. crassum (fig. CC, 21) and G. dorsum (fig. CC, 19).

Gyrodinium grave (Meunier)
Text figure DD, 7
Spirodinium grave Meunier (1910), p. 64, pl. 14, figs. 27, 28.

Draenosis.—A small species with stout ellipsoidal body, its length 1.29
transdiameters; girdle a descending left spiral, displaced 0.6 transdiameter,
constricting the body; sulcus extending from anterior end of girdle to near
antapex; surface finely striate. Length, 57”. Arctic Ocean off Nova Zembla.

DescripTION.—Body stout ellipsoidal, with broadly rounded apices, widest in the middle, its
length 1.29 transdiameters at the widest part. The epicone and hypocone are subequal. The
epicone is subhemispherical in outline, with a length on the left and right sides of 0.24 and 0.7
respectively of the total length of the body. The hypocone is broadly rounded with broad,
slightly flattened antapex.

The girdle in Meunier’s figure (1910, pl. 14, fig. 27, reproduced in our text figure DD, 7) is
not complete in its proximal end. This has been completed in our figure by the slender lines.
It joins the suleus at a distance from the apex of about 0.24 of the total length of the body. It
sweeps around the body in a descending left spiral of 1.25 turns, displaced posteriorly 0.6 trans-
diameter. It is wide, about 0.09 transdiameter, and deeply impressed with rounded borders.
The suleus extends from the proximal to the distal end of the girdle. It probably has a longer
extension posteriorly at least. Flagella are lacking in the figures given.

The nucleus is a large subspheroidal body found in the center of the organism. Its axis is
about 0.5 transdiameter in length. It is filled with coarse, chromatin strands. The surface is

310 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

covered with longitudinal equidistant lines, apparently equal in number on both epicone and
hypocone, about 30 across the ventral face. It is probable that they have more of a spiral
course than figured by Meunier.

Dimensions.—Lenegth, 57; transdiameter, 44; axis of nucleus, 22s,

OccuRRENCE.—Figured by Meunier (1910) as a rare species from the collec-
tions made by the Duke of Orleans’s Arctic Expedition of 1907 from the Arctic
Ocean near Nova Zembla.

Synonymy.—Originally described by Meunier (1910) as Spirodinium grave,
but is transferred by us to Gyrodiniwm.

Compartsons.—In the torsion of the body G. grave is nearest to G. intortum
sp. noy., a non-striate species of similar size and proportions, but with much
more recorded torsion of the suleus anteriorly. This furrow is not figured by
Meunier anterior to the girdle. Otherwise the species is unique in the genus
in form and torsion.

We have inverted Meunier’s (1910, pl. 14, fig. 27) figure and have completed,
as faint lines crossing the striae, the probable course of the distal end of the
girdle to its junction with the suleus. Our reasons for this change in orientation
are the facts that the proximal end of the girdle is usually the best developed
region, the distal end the least, in cases of modification in the course of the
girdle. In Meunier’s figures the animal is oriented with the proximal end
deficient. We turn the figure end for end and thus bring this deficient section
to the distal end.

Gyrodinium herbaceum sp. nov.
Plate 10, figure 109; text figure DD, 6

Dracnosis.—This is a small species with subovoidal body, its length 2.11
transdiameters; girdle a descending left spiral, displaced one transdiameter ;
sulcus short above and below junctions with girdle, with a torsion 0.5 turn;
surface finely striate; color, deep lichen green. Length, 38. Pacific off La
Jolla, California, July.

Description.—The body is subovoidal, widest near the middle, its length 2.11 transdiameters
at the widest part. In cross-section it is nearly cireular. The epicone is exceeded in size by the
hypocone, though its greatest length is 0.16 greater than that of the hypocone. The epicone is
subeonieal (60°) in shape, convex on the left and concave on the right side with a blunt, rounded
apex. Its length on the left and dorsal sides is about 0.32 of the total length of the body. Near
the right lateral margin of the body its length becomes greater, reaching posteriorly in a slender
point on the right side of the suleus for about 0.78 of the total length of the body. The hypocone
is broader than the epicone, its sides are more convex and the antapex broad and rounded.

The proximal end of the girdle joins the suleus at a distance from the apex of 0.32 of the
total length of the body. For the first half of its course it passes around the body in a nearly
transverse direction, then turns posteriorly in a steeply descending spiral and forms an angle of
about 35° with the median longitudinal plane of the body at its junction with the girdle at a
distance from the apex of 0.78 of the total length of the body. Its displacement is about one

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 311

transdiameter. The furrow has a width of about 0.08 transdiameter, and is deeply impressed
with smooth sides. The suleus extends but a short distance on the epicone and posteriorly it
fades out a short distance beyond its distal junction with the girdle. It turns towards the left
posteriorly with a torsion of about 0.5 turn. The anterior flagellar pore is found at the anterior
junction with the girdle, the posterior pore at the posterior junction.

The nucleus is spheroidal in shape and is located slightly above the central portion of the
body. It is filled with coarse, moniliform chromatin strands. Its axis is about 0.66 transdiameter
in length.

A large sacklike pusule opens into the anterior flagellar pore. The cytoplasm is clear and
transparent and contains many large blue-green oil drops, and dark refractive granules. In the
individual figured a large, green food mass was enclosed in a food vacuole, evidence of holozoic
nutrition. The surface of the body is striate with numerous, equidistant, blue-green striae, about
equal in number on the hypocone and epicone, 18 to 20 across the ventral face. The color is a
deep lichen green with tones of pearl grey. The whole organism has a highly refractive, glassy
appearance.

Drvenstons.—Length, 38; transdiameter, 18“; diameter of nucleus, 12+.

OccuRRENCE.—A single individual was taken July 13, 1917, with a No. 25
net, 1.25 miles off La Jolla, California, in a haul from 50 meters to the surface
and in a surface temperature of about 20°1 C.

Activitres.—It was in constant motion under the microscope, moving in
large circles counterclockwise, without rotation.

ComMPARISONS.—This species presents certain similarities in its girdle and
suleus arrangement to G. ochraccum (pl. 7, fig. 76; fig. DD, 17), having the
same amount of torsion but a slightly greater relative degree of displacement.
It differs from that species in its smaller size, greenish color and lack of pig-
ment, the possession of which is one of the most striking characteristics of
G. ochraceum. In size and proportions it is near G. viridescens sp. nov. (fig.
DD. 11), which has a much smaller epicone, and lacks the posterior torsion of
the sulcus.

Gyrodinium hyalinum (Schilling)
Text figure CC, 15

Gymnodinium hyalinum Schilling (1891), pp. 60, 61, pl. 3, fig. 14; (1891b), pp. 199-208,
pl. 10, figs. 1-22; as Spirodiniwm hyalinwm (1913), p. 21, fig. 2.

G. hyalinum, Ludwig (1898), p. 299.

G. hyalinum, Mez (1898), p. 216.

G. hyalinwm, Zacharias (1899), p. 144.

G. hyalinum, Schonichen and Kalberlah (1900), p. 231; (1909), p. 252.

Spirodinium hyalinum, Lemmermann (1900), p. 116; (1903), p. 260; (1910), pp. 565, 613,
627, figs. 24, 27, 31.

Gymondinium hyalinum Entz, Jr. (1902), p. 125; (1907), p. 17; (1909), p. 254.

G. hyalinum, Wesenberg-Lund (1904), p. 107.

G. hyalinum, Ruttner (1906), p. 6.

G. hyalinum, Dogiel (1906), pp. 32, 40.

G. hyalinum, Klebs (1912), pp. 391, 429, 430.

Spirodinium hyalinum, West (1916), p. 53, fig. 36c.

312 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

DracNosts.—A minute species with asymmetrical, ovoidal body, its length
1.36 transdiameters; girdle a descending left ‘spiral, displaced 0.35 transdiam-
eter; sulcus extending from girdle to antapex; no chromatophores. Length,
23.64, Fresh-water ponds in the Botanical Gardens at Basel, Switzerland.

DescripTIoN.—The body is irregularly ovoidal and widest in the middle, with broadly rounded
but asymmetrical apices, its length 1.36 transdiameters at the widest part. The hypocone exceeds
the epicone in extent, its length being greater by 0.27 of its own length. The epicone is broadly
rounded at the apex and has a length on the left and right sides of 0.17 and 0.44 respectively
of the total length of the body. It is oblique upon the right side. The hypocone is hemispherical
in outline in the posterior half, with broad antapex, but slightly oblique upon left side.

The left side of the girdle is placed far anteriorly, meeting the suleus at 0.17 of the total
length of the body from the apex. It passes transversely around to the dorsal side, where it
turns posteriorly in a descending left spiral course, displacing the right side of the girdle 0.35
transdiameter. The furrow is wide, about 0.23 transdiameter, and is deeply impressed with wide,
overhanging borders. Its anterior border on the right side of the body projects considerably
beyond the posterior lip and is less rounded. The suleus extends from the middle of the ventral
side to the posterior end of the body, but its position is not shown in Schilling’s (1891a, 6, 1913)
figures. The transverse flagellum traverses the entire length of the girdle, arismg presumably
at the proximal junction of the girdle and suleus. The longitudinal flagellum arises slightly
behind the distal end of the girdle.

Nucleus and pusules are not figured by Schilling. A small carmine-colored stigma is present
in the suleal region near the origin of the longitudinal flagellum. Nutrition is holozoic. Schilling
(1891b, pl. 10, figs. 5-7, 9-22) has described a process of food taking for this species, in which
amoeba-like pseudopods are formed to aid in the ingestion of small organisms. Unfortunately,
however, the connecting links between the Gymnodinium hyalinum and the amoeba-like forms
are lacking in his figures.

Dimenstons.—Length, 23.64; transdiameter, 20.7, as given in the text
(Schilling, 1891a, b, 1913). A careful measurement of his figure, however,
gives the transdiameter as 17.34. In the description above we have used the
latter measurement.

OccURRENCE.—Figured by Schilling (1891) from fresh-water ponds in the
Botanical Gardens at Basel, Switzerland.

SynonyMy.—Originally described by Schilling (1891) as Gymnodinium
hyalinum, this species was later transferred by Lemmermann (1900, 1903) to
Spirodinium. Schilling (1913) later accepted this allocation in his monograph
of German fresh-water dinoflagellates.

Comparisons.—This species and G. pusillwm form the only fresh-water
representatives in the genus. They greatly resemble each other in the position
of girdle, size, and shape. G. hyalinum lacks the chromatophores present in
G. pusillum.

Gyrodinium intortum sp. nov.
Text figure CC, 10

DraGNnosis.—A small species with broadly ellipsoidal body, its length 1.37
transdiameters; girdle a descending left spiral, displaced 0.4 transdiameter,
with an overhang of 0.6 transdiameter; sulcus with antapical loop and torsion
of 1 turn; color, green. Length, 624. Pacific off La Jolla, California, July.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 313

DescripTiIon.—The body is broadly ellipsoidal with broad apices, circular in cross-section, its
length 1.37 transdiameters at the widest part. The epicone and hypocone are subequal, the
epicone having a length greater by 0.12 of its length, but its transdiameter is less than that of
the hypocone. The epicone has a length from the proximal and distal ends of the girdle of about
0.4 and 0.69 respectively of the total length of the body. It is irregularly convex-conical with
broad, rounded apex. The hypocone has a slightly greater transdiameter than the epicone,
broad posteriorly, subtruneate with a broad, shallow suleal notch.

The girdle is a descending left spiral of 1.6 turns with a displacement of 0.4 transdiameter.
Its distance from the apex at its proximal and distal ends is about 0.4 and 0.69 respectively of
the total length of the body. Its course for the proximal and distal thirds of its length is nearly
transverse, the greatest posterior deflection oceurring in the middle third on the dextrodorsal
surface of the body. The furrow is relatively narrow, its width about 0.04 transdiameter, deeply
impressed, the exeavation undereutting both borders slightly.

The suleus invades the epicone in a long apical loop which encircles the apex and terminates
on the sinistrodorsal surface some distance posterior to the apex. The suleus continues its spiral
course beyond the anterior junction with the girdle, with a sinistro deflection of 0.6 transdiameter
in the intercingular area before meeting the distal end of the girdle. Posteriorly it passes
directly to the antapex, where it forms a broad, shallow notch. The furrow is shallow and
slightly more than half as wide as the girdle. Posterior to the distal junction it becomes deeply
impressed, with the right border drawn out into a flap which nearly covers the channel. The
anterior flagellar pore opens at the proximal junction of the girdle and sulcus, the posterior pore
midway between the distal one and the antapex. It lies at the apex of the angle formed by the
right border of the sulcus and the furrow. The transverse flagellum traverses the entire length
of the girdle.

The nucleus is an ellipsoidal body lying in the posterior part of the body near the distal
junction of the girdle and suleus. Its major and minor axes are 0.44 and 0.33 transdiameter
respectively in length.

The cytoplasm is very clear and transparent, its granular structure scarcely perceptible.
The anterocentral part of the body is filled with a large food mass showing traces of a dinofla-
gellate girdle, olive yellow in color with smaller, slightly darker granules of the same color. The
peripheral layer of cytoplasm is marked by a reticulum of vetiver green with a background of
pale glaucous green. Nutrition is holozoie.

Ditenstons.—Length, 62”; transdiameter, 45; axes of nucleus, 20” and 15.

OccURRENCE.—This was observed on July 20, 1917, 6 miles off La Jolla,
California, in a haul from 80 meters to the surface and in a surface temperature
ob 21.

Comparisons.—This is one of the most aberrant species in the genus Gyro-
dinium. Its suleus strikingly resembles that found in Pouchetia (as in P.
maculata (pl. 11, fig. 119) and P. schuetti (fig. PP, 10) in its well developed
apical loop, and is quite unlike that found elsewhere in the genus Gyrodinium.
Its length of girdle, amount of girdle displacement, and lack of an ocellus leaves
no doubt as to its status generically. In its reticulate peripheral zone it
resmbles Cochlodinium clarissimum (pl. 5, fig. 60).

It belongs in the subgenus Laevigella, though it is not closely related to any
other member of that group.

314 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Gyredinium lachryma (Meunier)
Text figure EE, 6

Spirodinium lachryma Meunier (1910), p. 63, pl. 14, figs. 21, 22.

Diacnosis.—A medium sized species with ovoidal body, its length 2.83 trans-
diameters; girdle a descending left spiral, displaced 1.4 transdiameters; sulcus
extending from the anterior end of girdle to antapex. Length, 105. Kara Sea
off Nova Zembla, July.

Description.—The body is ovoidal, broadly rounded posteriorly and gradually tapering to a
slender point anteriorly, its length 2.83 transdiameters at the widest part. The epicone exceeds
the hypocone in length by 0.42, but its narrower width makes their relative proportions nearly
equal. It is slender conical anteriorly (25°) with a narrow, pointed apex and expanding to
about 66° in the region of the girdle. It has a length on the left and right sides of 0.45 and 0.90
respectively of the total length. The hypocone is subhemispherical posteriorly with a broad,
rounded antapex.

The girdle meets the proximal end of the sulcus at a distance from the apex of 0.45 of the
total length of the body. It follows a steeply descending left spiral course around the body and
meets the distal end of the suleus about 0.9 of the total length of the body from the apex, being
displaced posteriorly 1.4 transdiameters. The furrow is not well marked out in Meunier’s (1910)
figures, but its width seems to be about 0.19 transdiameter and it is rather shallow. The flagella
are also omitted from his figures. The suleus begins at the proximal end of the girdle and
extends posteriorly to near the antapex.

The nucleus is large, ellipsoidal and is found in the center of the body with its major axis
parallel to the long axis of the body. Its major and minor axes are about 0.9 and 0.4 trans-
diameter in length respectively. It is filled with loose chromatin strands following its longer
axis. The peripheral zone of cytoplasm is filled with small, closely crowded rodlets arranged
radially in Jongitudinal rows. Color?

Dimenstons.—Length, 105; transdiameter, 37; axes of nucleus, 34 and 14.

OccURRENCE.—Figured as a rare species by Meunier (1910) from the collec-
tions of the Duke of Orleans’s Arctic Expedition of 1907 from the Kara Sea
off Nova Zembla, July 30, in a haul from a depth of 127 meters.

Comparisons.—This species is close to G. contortum (Schiitt) (fig. CC, 22),
but differs from it in its more tapering epicone, more rotund hypocone, less
torsion, and wider intercingular area.

Gyrodinium longum (Lohmann)
Text figure DD, 10

Cochlodinium longum Lohmann (1908), p. 264, pl. 17, fig. 22.
C. longum, Paulsen (1908), p. 104, fig. 144.
C. longum, Ostenfeld (1913), p. 388.

Diacnosis.—A rather small species with slender subfusiform body, its length
2.69 transdiameters; girdle a descending left spiral, displaced 1.06 transdiam-
eters; surface striate; color, light yellow. Length, 70". Baltic Sea off Kiel,
Germany, June.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 315

DEscripTion.—The body is irregularly fusiform, widest anteriorly, its length 2.68 transdiam-
eters at the widest part, which is in the lower epicone. The epicone exceeds the hypocone in length
by 0.25 of its own length. It is conical anteriorly (45°) with a blunt apex. It has a length on
the left and right sides of 0.37 and 0.56 respectively of the total length of the body. The
hypocone narrows behind the girdle to about 0.5 the width anteriorly. The antapex is obliquely
truncate with a small knoblike projection from the center of the truncate surface.

The girdle begins at a distance from the apex of about 0.37 of the total length of the body.
It passes around the body in a descending left spiral direction and terminates at a distance from
the apex of 0.56 of the total length of the body, being displaced 1.06 transdiameters. The
furrow is wide, about 0.1 transdiameter, and quite shallow. The suleus is not shown in Lohmann’s
(1908) figure.

The nucleus is an ellipsoidal body near the center of the organism. Its major and minor
axes are about 0.7 and 0.53 transdiameter in length respectively. The other eytoplasmie inclu-
sions are very sparse and include three brownish food masses and several minute spherules. The
surface of the body is covered with parallel longitudinal striae of granules linearly arranged,
about 13 across one face. Unfortunately the striae are not shown in our figure as converging
towards the apex as in Lohmann’s original figure. The color of the body is light yellow.

Dimenstons.—Length, 70; transdiameters, 26; axes of nucleus, 184 and 13+.

OccuRRENCE.—Figured by Lohmann (1908) from collections made in the
Baltic Sea off Kiel, Germany, in June.

Discusston.—This species was originally described by Lohmann (1908) as
Cochlodinium longum. His figure, however, does not show the characteristic
Cochlodinium arrangement of girdle, that is, with the torsion of the body giving
the girdle a length of at least 1.5 turns around the body. Neither is it possible
with the furrows as drawn to force a Cochlodinium interpretation of the species.
On the contrary, there seems to be a total lack of torsion with the girdle making
but one spiral turn around the body. His figure also seems to be inverted with
the girdle of the two faces drawn as though both parts were on the upper
surface. In the reproduction of his figure, given herewith in our text figure
DD, 10, these changes embodying our interpretation are incorporated, bringing
his figure into conformity with other species of Gyrodinium. We therefore
place Lohmann’s species tentatively in the genus Gyrodinium as Gyrodiniwm
longum (Lohmann).

It is quite possible that the drawing of this species is not inverted, and that
a whole turn or more of the girdle is omitted in Lohmann’s drawing, in which
case the species is a Cochlodinium. Few, if any, Gyrodinium have the epicone
so pronouncedly larger than the hypocone as it is in G. longum as we orient
the body.

Gyrodinium maculatum sp. noy.
Plate 6, figure 62; text figure DD, 19

DraGnosis.—A medium sized species with ellipsoidal body, its length 1.49
transdiameters; sulcus extending from below the apex to antapex; girdle a
premedian, descending left spiral, displaced 0.56 transdiameter; surface finely
striate; violet pigment in epicone. Length, 61-. Pacific off La Jolla, California,
July, August.

316 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

DescripTION.—The body is broadly ellipsoidal with broadly rounded, faintly subconical apices,
its length 1.49 transdiameters at the widest part, which is below the girdle. A cross-section is
nearly cireular in outline. The hypocone exceeds the epicone in size, its length being greater by
0.2 of the total length. The epicone is rounded conical in shape, with broad, smoothly rounded
apex. It has a length on the left and right sides of 0.21 and 0.57 respectively of the total length
of the body. The hypocone has a length on the left and right sides of 0.73 and 0.4 of the total
length of the body. Its sides are somewhat more convex than those of the epicone and taper more
towards the antapex, which is usually narrower than the apex. The right side of the body has
a slightly greater convexity than the left side.

The girdle is premedian in position for the greater part of its course. Its proximal end joins
the suleus at a distance from the apex of 0.21 and its distal end 0.57 respectively of the total
length of the body. The first 0.5 transdiameter of its course follows an almost transverse direction
around the body, beyond which it turns posteriorly in a gradually steepening angle which becomes
about 45° with the longitudinal plane of the body, at its junction with the sulcus. The furrow
has a width of about 0.06 transdiameter and is deeply impressed, undercutting the lip on the
anterior side and sloping gradually out to the posterior lip. The suleus begins below the apex
and extends posteriorly to near the antapex in a sinuous, slightly sigmoid curved line. It begins
as a shallow trough and deepens through the intercingular part of its course, becoming shallow
distally and fading out near the antapex. The anterior flagellar pore opens at the anterior
junction of the girdle and suleus, the posterior pore about one width of the girdle below the
distal junction.

The nucleus is a relatively large, spheroidal body filled with coarse, moniliform chromatin
strands, which lie in the longitudinal plane. It is situated in the anterior part of the body or
immediately dorsad from the intercingular region. Its axis is about 0.48 transdiameter in length.

Large, sacklike pusules are usually present at either or both pores. The cytoplasm is very
finely granular, clear, and transparent. Food inclusions are usually present in the body, indi-
eating a holozoic mode of nutrition. In the individual figured a large mass, buffy citrine in
color, filled the posterior part of the body immediately behind the nucleus. A few minute
refractive granules were scattered through the cytoplasm near the nucleus. The cytoplasm is
pearl grey in color.

The most striking feature of this organism is its pigmented coloration. This is found in the
cuticular layer and along the lines of striae. The surface is closely beset with equidistant, longi-
tudinal lines, having a very faint, fluorite violet color. These are about 2.5 times as numerous
on the hypocone as on the epicone, where there are 15 across the ventral face. They are further
marked, generally throughout their entire length, by minute granules, fluorite violet in color,
strung along the lines like beads on a string. The number of these varies slightly in different .
individuals and they are frequently scanty in the antapical region. In addition to these the
peripheral zone in the epicone contains large agglomerated masses of the same pigment. The
color of these larger masses 1s frequently so deep as to appear almost black when viewed under
the low powers of the microscope. This pigment evidently has the same power of movement as
that found in Gymnodinium lineopunicum and Gyrodinium ochraceum.

Divensions.—Length, 61-73; transdiameter, 41-54; axis of nucleus,
20-22,

OccURRENCE.—The first specimen was taken July 5, 1904, 12 miles off Point
Loma, California, with a No. 20 silk net, in a haul from 355 meters to the
surface. It was again met with July 3, 1916, in a surface haul made at the end
of the pier at the Biological Station at La Jolla, California. Throughout July
and August, 1917, it was present in most of the hauls made at La Jolla, both
in surface hauls and in the deeper hauls made farther offshore. The individual

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 317

figured was taken August 18, 4 miles offshore, from 80 meters to the surface
and in a surface temperature of 20°2 C,

Activities.—These are active little forms in constant motion until slowed
down by the adverse conditions found under the microscope. They move about
in a loose spiral with a slow, clockwise rotation, varied with short periods of
rapid whirling with the dorsal side uppermost.

Comparisons.—This is one of the few species below Pouchetia which
possess pigment capable of active movement, and is probably near the line of
evolution of that genus. The other members of Gyrodinium which are aligned
with it in this respect are G. ochraceum, G. corallinum, and G. virgatum. In
its girdle arrangement this species shows a close relationship with G. fissuim
(fig. DD, 8), G. corallinum (fig. DD, 12), and G. pingue (fig. DD, 15). The
surface striae are also like those of G. corallinwm and G. fissum.

Gyrodinium melo sp. noy.
Plate 5, figure 50; text figure CC, 9
DraGnosis.—A medium sized species with rotund ovoidal body, its length
1.42 transdiameters; girdle a descending left spiral, displaced 0.53 transdiam-
eter; sulcus extending from apex to antapex; color, grey with green chromato-
phores. Length, 664. Pacific off La Jolla, California, July.

DeEscrteT1IoN.—The body is rotund ovoidal, rounded posteriorly, tapering slightly anteriorly,
its length 1.42 transdiameter at its widest part, which is equatorial in location. In cross-section
the body is circular in outline. The hypocone exceeds the epicone in size, having a slightly
greater length and a continuously greater transdiameter. The epicone has rounded sides and a
short bluntly acuminate apex. It has a length on the left and right sides of 0.19 and 0.53
respectively of the total length of the body. The hypocone is elongate hemispherical with a
symmetrically rounded antapex.

The girdle is a descending left spiral with a displacement of 0.53 transdiameter and an
overhang of about 0.25 transdiameter. Its proximal end joins the sulcus at a distance from the
the apex of 0.19 of the total length of the body. For the first 0.5 transdiameter of its course its
direction is transverse beyond which it turns posteriorly on the dorsal face at an angle of about
55°, joining the sulcus distally about 0.53 of the total length of the body from the apex. The
furrow has a width of about 0.06 transdiameter and is deeply impressed with smooth borders.
The suleus invades the epicone nearly te the apex and extends posteriorly to within a short
distance of the antapex in a sigmoid line. It is rather shallow and fades out near the apices.
The anterior flagellar pore opens at the proximal junction of the girdle and sulcus, the posterior
pore about two widths of the girdle below the distal junction.

The nucleus is a large spheroidal body filled with coarse, moniliform chromatin strands. It
is located dorsad to the intercingular area. Its axis is about 0.34 transdiameter in length.

The cytoplasm is coarsely granular and contains food masses, vacuoles, and a few minute,
refractive granules. In the posterior part of the individual figured is a large, orange-rufous
body, with a smaller body, brighter red in color, lying near it. In the anterior part of the body
are three large vacuoles, one filled with a blue fluid, the others with a grey fluid. The general
color of the cytoplasm is grey with darker tones in the peripheral zone. This zone also contains
the irregular, leaflike, apple-green chromatophores. Nutrition is possibly both holophytie and
holozoic, as the presence of both chromatophores and food bodies in the cytoplasm may indicate.

318 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Drvensions.—Length, 61-674; transdiameter, 43-474; transdiameter of
nucleus, 19.

OccuRRENCE.—T wo individuals only of this species were observed. The first
was taken on July 21, 1917, in a surface haul at the end of the pier at the
Biological Station at La Jolla, California, with a No. 25 silk net. The second
individual was taken July 22 at the same place and with the same apparatus.

Comparisons.—The coincident presence of chromatophores and food bodies,
evidence of both holozoic and holophytic nutrition, is not an unknown phenom-
enon in the Gymnodinioidae. The same thing is found in Amphidinium steint
(Stein, 1883, pl. 17, figs. 14-16), Gymnodinium flavum sp. nov., G. ravenescens
sp. nov., G. fulgens sp. nov., and G. herbaceum sp. nov. (figs. X, 7, 21, 30; Y, 17).
The presence of chromatophores is relatively rare in this genus, only three
other species possessing them, G. falcatun sp. nov., G. foliaceum sp. nov., and
G. pusillum (Schilling) (fig. CC, 11, 18,3). It is close to G. foliaceum (fig. CC,
18), but is larger, with more displacement of the girdle and torsion of the body.

Gyrodinium mitra nom. sp. noy.
Text figure EE, 5

Gymnodinium spirale var. mitra, Schiitt (1895), pl. 21, fig. 68a.
Spirodinium spirale var. mitra, Lemmermann (1899), p. 359.

Diacnosis.—A rather small species with an asymmetrical subfusiform body,
its length 2.6 transdiameters; girdle a descending left spiral. displaced 1.17
transdiameters; sulcus joining ends of girdle. Length, 78. Atlantic or Bay
of Naples.

DEscrRIPTION.—The body is asymmetrical subfusiform, with a greater convexity on the right
side of the epicone, tapering towards both apices, its length 2.6 transdiameters at the widest part
which is anterior. The epicone exceeds the hypocone in size, its transdiameter being slightly
greater and its length greater by 0.15 of itself. It is asymmetrical, the right side convex and
the left nearly longitudinal, throwing the narrowly rounded apex strongly to the left. It has a
length on the left and right sides of 0.29 and 0.75 respectively of the total length of the body.
The hypocone is also asymmetrical, with a sigmoid outline on the left side, nearly straight on
the right, throwing the antapex towards the right, but with less deflection than in the apex. It
is narrower than the epicone with a slender blunt antapex.

The girdle is a descending left spiral distant from the apex at its proximal and distal ends
about 0.29 and 0.75 respectively of the total length of the body. It is displaced about 1.17
transdiameters with a slight overhang. Its proximal end turns abruptly posteriorly at an angle
of 50° with the longitudinal plane of the body, until it reaches the left lateral border where it
turns and passes across the dorsal face in an almost transverse direction, turning again poster-
iorly near the right lateral margin and traversing the right ventral face at an angle of about
55° with the longitudinal plane. The furrow has a width of about 0.14 transdiameter and is
deeply impressed with smooth borders. The suleus in Schiitt’s (1895) figure does not extend
beyond the intercingular region where its width is nearly equal to that of the girdle.

The nucleus is a rather large, ellipsoidal body, densely filled with short chromatin strands
and located in the anterocentral part of the body. Its major and minor axes are about 0.75 and
0.5 transdiameters in length respectively.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 319

The peripheral zone of cytoplasm is filled with short rodlets, presumably arranged at right
angles to the surface, as in other species, but these are not figured by Schiitt, who also omits oil
vacuoles in the cytoplasm. Color?

DimMeEnstons.—Length, 78; transdiameter, 30; axes of nucleus, 23 and 17+.

OccURRENCE.—Figured by Schiitt (1895) from material collected by the
Plankton Expedition, presumably from the Atlantic or from Bay of Naples.

SynonyMy.—This was figured by Schiitt (1895) as Gymnodinium spirale
var. mitra and changed by Lemmermann (1899) to Spirodinium spirale var.
mitra. It lacks the characteristic striate surface of spirale, however, and is
also distinct from that species in its proportions; hence it can hardly be regarded
as a variety of that species. We therefore propose for it specific rank under
Schutt’s varietal name.

Gyrodinium obtusum (Schiitt)
Plate 9, figure 103; text figure DD, 3

Gymnodinium spirale Bergh var. obtusa Schiitt (1895), pl. 22, fig. 70:

Spirodinium spirale var. obtuswm, Lemmermann (1899), p. 359.

S. spirale var. obtusa, Schroder (1900), p. 13.

G. spirale var. obtusum, Lebour (1917b).

Not Gymnodinium spirale var. obtuswm Dogiel (1906), pp. 38-43, pl. 2, figs. 50-56 (—
Gymnodinium heterostriatum nom. sp noy.).

Draanosis.—A medium sized species with ellipsoidal subsymmetrical body,
its leneth 1.75 transdiameters; girdle a descending left spiral, displaced one
transdiameter; suleus extending from apex to antapex; surface finely striate
with broken striae; color, amber yellow. Length, 70#. Pacific off La Jolla,
California, July; Atlantic, Gulf of Naples, Plymouth Sound, EngInd.

DeEsScRIPTION.—The body is moderately broadly ellipsoidal with broad, rounded apices, widest
in the middle, its length 1.75 transdiameters at the widest part. A cross-section of the body is
nearly circular in outline. The hypocone is slightly larger than the epicone, though the posterior
deflection of a triangular portion of the epicone on the right ventral face gives it a greater
length than the hypocone. The epicone is convex conical (75°) with broad, blunt apex. It has
a length on the left and right sides of 0.22 and 0.80 respectively of the total length of the body.
The greatest increase in its length is made on the right side of the ventral face where the distal
border forms an angle of 45° with the longitudinal plane. The hypocone is somewhat broader
than the epicone with a broader, more blunt antapex. It has a length on the left and right sides
of the body of 0.18 and 0.72 respectively of the total length of the body.

The girdle forms a steeply descending left spiral, displaced one transdiameter or 0.57 of the
total length of the body. Its proximal end joins the sulcus at a distance from the apex of 0.22
and its distal end 0.8 of the total length of the body. The first 0.5 transdiameter of its course is
in a transverse plane, the remainder a gradually steepening spiral which forms in the last 0.5
transdiameter, an angle of 45° with the longitudinal plane of the body. The furrow has a width
of about 0.06 transdiameter and is deeply impressed, its concavity undercutting the anterior
border and sloping gradually out to the posterior one. The sulcus extends from the apex to the
antapex in a nearly straight line. The trough is narrower than the girdle, shallow on the epicone,

320 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

becoming deeper in the intercingular area and the antapical region. The anterior flagellar pore
is located at the anterior junction of the girdle and suleus, the posterior pore about one width of
the girdle below the distal junction.

The nucleus is an ellipsoidal body filled with coarse, moniliform subparallel chromatin strands
in the posterocentral part of the body. Its major and minor axes are about 0.64 and 0.35 trans-
diameter in length respectively.

The sacklike pusule at the anterior pore is connected by a long tubular canal with the pusuie
at the posterior pore, the whole structure forming a complete channel between the two openings.
The cytoplasm is finely granular and diffusely amber yellow in color. In the peripheral zone
are numerous, short, slender blue-green rodlets or rhabdosomes arranged at right angles to the
surface. In a surface view these appear as minute blue-green circles. The surface is finely
striate with equidistant blue-green striae composed of linear series of short dashes, about 28
across the ventral face of the epicone. These are about twice as numerous on the hypocone as
on the epicone.

Dimenstons.—Length, 70+; transdiameter, 394; axes of nucleus, 254 and 14#.

OccURRENCE.—This species was first observed July 12, 1903, in a surface
haul off La Jolla, California. It was met again July 9 and 11, 1917, in hauls
4 miles off shore, from 80 meters to the surface and in a surface temperature
of 19°8 C.

Other records of the occurrence of this species are as follows: Schiitt
(1895) figures it from the material of the Plankton Expedition, presumably
from the Bay of Naples or the Atlantic, Schréder (1900) lists it from the Gulf
of Naples, and Lebour (1917)) records it from Plymouth Sound, England.

SynonyMy.—Originally figured by Schutt (1895, pl. 22, fig. 70) as Gymno-
dinium spirale Bergh var. obtusa and later transferred by Lemmermann (1899)
to Spirodinium by reason of its spiral girdle. Dogiel (1906) describes a
Gymnodinium under this name, specifying neither new species nor Schiitt as
authority. His form is not, however, that which Schiitt (1895) has figured.
It is larger, has greater contrast in the intervals between the ribs in the epicone
and hypocone, a straighter longitudinal furrow, and very little displacement of
the distal end of the girdle below the proximal. This is 0.42 of the total length
in Schiitt’s figure and only 0.05 in Dogiel’s. The latter must therefore belong
in Gymnodinium. It appears to be identical with our Gymnodinium hetero-
striatum.

Comparisons.—A peripheral zone of short rodlets is not uncommon in both
Gyrodinium and Gymnodinium and is probably related to the metabolism of
the cell. These are most marked in Gyrodinium fissum (fig. DD, 8) and G.
postmaculatum (fig. DD, 20). The long radial rodlets are also repeated in
Gymnodinium pseudonoctiluca, G. dogieli (pl. 3, fig. 34), G. pachydermatum
(pl. 8, fig. 32), and G. amphora (pl. 3, fig. 26). These are not present in all
individuals of the species and are probably related to certain stages of
metabolism.

This species is close to G. fissum (Levander) (fig. DD, 8), but is vellow
instead of green, has much greater displacement of girdle, and broken lines in
its striae instead of continuous ones.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 321

Gyrodinium ochraceum sp. noy.
Plate 7, figures 76, 82; text figure DD, 17

DriaGnosts.—A large species with bullet-shaped body, its length 2.28 trans-
diameter; girdle a descending left spiral with overhang of 0.4 transdiameter
and displacement of 1.04 transdiameters ; sulcus extending from apex to antapex
in a left spiral of 0.5 turn; surface striate; color, ochraceous orange. Length,
123. Pacific off La Jolla, California, July.

DescripTioN.—The body is of robust habit, circular in cross-section; bullet-shaped with
pointed anterior end, rounded posteriorly, its length 2.28 transdiameters at the widest part
which is postmedian. The sides may be subparallel (pl. 7, fig. 76) or the dorsal surface may be
convex and the ventral concave (pl. 7, fig. 82). The epicone and hypocone are subequal in size,
though the greatest length of the epicone exceeds that of the hypocone by 0.24 of its own length.
The epicone is elongate conical in outline, about 60° above the anterior pore, with convex sides
and pointed apex. Its length on the left of the sulcus is about 0.35 and on the right is 0.87 of
the total length of the body. Along the girdle it flares out abruptly into a narrow shelflike
projection. The hypocone is dome-shaped with broadly rounded antapex. Like the epicone it
forms a narrow, shelflike projection along the posterior border of the girdle. There is no suleal
notch at the postmargin.

The junction of the girdle and suleus occurs at a distance from the apex of about 0.35 of the
total length of the body. It forms a descending left spiral which is displaced posteriorly on the
right side about 1.04 transdiameters, with an overhang of about 0.4 transdiameter. It lies in a
wide, deep depression with wide overhanging, shelflike borders. The anterior flagellar pore is
located at the anterior junction of the girdle and sulcus and the posterior pore midway between
the posterior junction and the antapex.

The suleus begins at or near the apex and extends to the antapex in a spiral course. Below
the anterior pore it widens, contracts just above the distal junction and posteriorly expands into
a wide trough which reaches the antapex, making 0.5 turn of a left spiral to the opposite face.
It lies in a deep depression with high, smoothly rounded borders.

The nucleus is subspherical or slightly ellipsoidal and located in the middle regions on the
right side of the body. It is filled with coarse, moniliform chromatin strands. Its axis is 0.5
transdiameter in length.

A long pusule, variously lobed and branched, opened into both flagellar pores, the expanded
portions being connected by a long slender canal. The cytoplasm is clear and transparent and
yellowish grey in color. Food inclusions of any kind were extremely rare in all the individuals
of this species observed. The surface is finely striate with equidistant blue-green lines. These
are about 2 apart at the girdle, about 25 across the ventral face, and are approximately equal
in number on epicone and hypocone. The general color of the body is yellow green with
ochraceous-orange granules thickly scattered in the surface cytoplasm. This colored pigment
possesses remarkable powers of amoeboid activity. In the first specimen observed it was collected
in rounded granules scattered thickly over the surface with a mass in the apieal region (pl. 7,
fig. 76). Later these became grouped on the dorsal surface and along the region of the girdle,
forming a wide band similar to that observed in another individual. The second individual was
found in the same material with the color massed in a long bandlike zone with irregular margins,
following the girdle around the body. After an hour and a half on the slide under observation,
the edges of the band became more ragged and small particles were pinched off. These rounded
up and moved out over the surface. Two hours later the entire pigment mass had thus become
broken up into small granules evenly distributed over the body. Another individual was observed
in which the small pigment granules were in the act of becoming agglomerated along the girdle
into one long band.

322 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Drvensions.—Length, 110-1234; transdiameter, 45-554; axis of nucleus,
21-22.

OccuURRENCE.—Two individuals were taken July 12, 1917, 6 miles off La
Jolla, California, with a No. 25 net, in a haul from 80 meters to the surface and
in a surface temperature of 20° C. The following day it was observed in a
haul taken with the same apparatus 1.25 miles offshore and from 50 meters to
the surface. On July 20 it was taken in a haul 6 miles offshore and on July 27
at 4 miles off La Jolla. These were taken with the same apparatus, from 80
meters to the surface and in surface temperature of 20°5 C and 21°4 C respec-
tively. It was fairly abundant in this material, seven individuals being observed
in a short examination of the last haul.

Acrivities.—These organisms are rather slow in their movements, moving
around in large clockwise circles with anticlockwise rotation, changing the
direction by a sudden jerk from right to left, sometimes turning in this manner
fully 90° or slightly more, and continuing in a new spiral.

Compartsons.—The most remarkable feature of this organism is the amoe-
boid activity of the pigment, resembling, in this respect, Gymnodinium punicum,
and foreshadowing the condition established in Pouchetia and Erythropsis.
Other species, as Gyrodinium maculatum, show the presence of mobile pigment,
but this is less active in these species in its movements.

In its type of structure and proportions this species stands near G. spirale
(fig. DD, 14). The latter, however, shows a total lack of pigmentation. In
its girdle arrangement it stands near the border line between Gyrodiniuwm and
Cochlodinium. The greater amount of torsion of the sulcus occurs posteriorly
to the intercingular space as contrasted with its occurrence in the intercingular
space in Cochlodinium. It stands near G. contortum (Schiitt) (fig. CC, 22) of
the subgenus Lacvigella in the wide displacement and overhang of its girdle,
resulting from the torsion of the intercingular sulcus.

The motility of its yellow-ochre pigment finds its parallel in Gymnodinium
lineopunicum and in the amoeboid-pigment masses of the more highly special-
ized genera, Pouchetia and Erythropsis. In all of these, however, the pigment
shows some shade of red or black, this species being distinct In the possession
of a yellow-ochre pigment.

Gyrodinium ovatum (Gourret)
Text figure EE 7

Gymnodinium ovatum Gourret (1883), p. 88, pl. 1, fig. 22.

DiaGnosis.—A small species with fusiform body, its length 2.88 transdiam-
eters; girdle a descending left spiral, displaced 0.92 transdiameter; sulcus
extends from the girdle to the antapex; color, yellow. Length (?). Gulf of
Marseilles, France.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 323

Description.—The body is slender fusiform with rounded apices, its length 2.88 transdiam-
eters at the widest part. The epicone greatly exceeds the hypocone in extent, its length being
greater by 0.46 of its own length. It has a length on the left and right sides of 0.51 and 0.87 of
the total length of the body. The dorsal side is somewhat less symmetrical than the ventral,
tapering more abruptly to the narrow, rounded apex. The hypocone is broader posteriorly than
the epicone with broad, rounded antapex.

The girdle lies almost entirely posterior to the equatorial plane of the body. It meets the
sulcus at a distance from the apex of 0.51 of the total length of the body. It follows a descending
left spiral course around the body, displaced about 0.92 transdiameter, its distal end joining the
suleus about 0.12 of the total length of the body from the antapex. The suleus extends from the
proximal end of the girdle to the antapex as a rather deep furrow.

The nucleus is a small, spherical body found in the median ventral part of the cytoplasm.
It is homogenous with clear, central, hyaline nucleolus. The body figured here by Gourret (1883)
is unlike the nuclei found throughout the Gymnodinioidae both in relative size and structure
and is probably a vacuole. The central part of the cytoplasm is granular and filled with oil
droplets, with a hyaline zone near the periphery. The organism is yellow in color.

Dimenstons.—No dimensions are given by Gourret and the magnification
of his figure could not be determined.

OccuRRENCE.—Gourret (1883) figured this species from the Gulf of
Marseilles, France.

SynonyMy.—This form was described by Gourret as Gymnodinium ovatum.
Its girdle arrangement excludes it from that genus and it is here placed with
Gyrodinium as G. ovatum (Gourret).

Comparisons.—This species is near G. contortum (Schiitt), but differs from
it in having a displacement of the girdle of about 0.33 of the total length as
compared with 0.5 in G. contortum.

Gyrodinium ovoideum sp. nov.
Plate 9, figure 106; text figure CC, 6

Diacnosis.—A rather large species with rotund ellipsoidal body, its length
1.28 transdiameters; girdle a descending left spiral, displaced 0.37 transdiam-
eter; sulcus extending from girdle to antapex; color, dilute primuline yellow.
Length, 72. Pacific off La Jolla, California, May to August.

DescripTion.—The body is stout, rotund ellipsoidal with broadly rounded apices, circular in
cross-section, its length 1.28 transdiameters at the widest part. The epicone and hypocone are
subequal in size. The epicone is subhemispherical in outline, its size smoothly rounded and apex
broad. It has a length on the left and right sides-of 0.34 and 0.61 respectively of the total length
of the body. The hypocone is also subhemispherical in shape without suleal notch at the antapex,
its length nearly approximating that of the epicone.

The girdle is submedian in position, its proximal and distal ends meeting the suleus at a
distance from the apex of 0.34 and 0.61 respectively of the total length of the body. It forms a
descending left spiral with its distal end displaced 0.37 transdiameter, and with a slight overhang.
The furrow has a width of about 0.07 transdiameter and is deeply impressed with. smooth
rounded borders. The suleus may invade the epicone for a short distance or may stop with the
proximal margin of the girdle. It extends posteriorly in a sinuous line as a shallow trough
which fades out near the antapex. The anterior flagellar pore is located at the proximal junction
of the girdle and sulcus, the posterior pore slightly posterior to the distal junction.

324 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The nucleus is ellipsoidal in shape and located in the anterocentral region. Large, moniliform
chromatin strands traverse its longer axis. Its major and minor axes are about 0.5 and 0.4
transdiameter in length respectively.

A large sacklike pusule opens into each flagellar pore. The cytoplasm is granular and often
contains a large, reddish-brown food mass, with numerous blue-green and small refractive
spherules. These latter inclusions indicate a holozoic mode of nutrition. Striations and other
surface markings could not be detected. The general color of the organism is dilute primuline
yellow mixed with pearl grey and orange, diffused throughout the cytoplasm.

Dimensions.—Length, 45-74“; transdiameter, 34-604; axes of nucleus,
29-33» and 23-244,

OccURRENCE.—The first individual was taken May 31, 1904, in a surface haul
9 miles off La Jolla, California. On June 24, 1917, it was found in the surface
haul taken at the end of the pier at the Biological Station at La Jolla. It was
also taken August 10 1 mile offshore in a haul from 50 meters to the surface
and on the 15th 0.75 mile offshore in a haul from 83 meters to the surface.

ComPartsons.—This species is near G. ovum (Schutt) ( fig. CC, 8), but is
large with relatively much less displacement of the girdle, more symmetrical
hypocone, and shorter sulcus.

Gyrodinium ovum (Schiitt)
Text figure CC, 8

Gymnodinium ovum Sehiitt (1895), pl. 25, fig. 23.
G. ovwm, Calkins (1901), p. 118, fig. 64 A.

Diacnosts.—A small species with ellipsoidal body, its length 1.4 transdiam-
eters; girdle a descending left spiral, displaced 0.6 transdiameter; sulcus ex-
tending from girdle to antapex; color (?). Length, 284. Atlantic (?) or Bay
of Naples.

DescripTion.—The body is broadly ellipsoidal with broad, rounded apices, its length 1.4
transdiameters at the widest part, which is at the middle. The epicone exceeds the hypocone in
size, its length being greater by 0.11 of its own length. It is elongate, subhemispherical in shape,
with broad, rounded apex. It has a length on the left and right sides of 0.32 and 0.68 respec-
tively of the total length of the body. The hypocone is shghtly less symmetrical than the epicone
and notched on the left side of the antapical region by the distal end of the suleus.

The girdle is submedian in position, its proximal end joining the sulcus at a distance from the
apex of 0.32, its distal end 0.68 respectively of the total length of the body, forming a descending
left spiral displaced 0.6 transdiameter. The furrow has a width of about 0.12 transdiameter
and is rather shallow. The suleus begins at the girdle and extends posteriorly in a sinuous line
to the antapex. The flagellar pores were not figured by Schiitt, though he shows the distal ends
of both the transverse and longitudinal flagella.

The nucleus is an ellipsoidal body filled with coarse chromatin strands and lying in the right
central part of the body. Its major and minor axes are about 0.62 and 0.37 transdiameter in
length respectively.

The cytoplasm is filled with small spherules and contains besides these, vacuoles, and one
large, spheroidal, brownish food mass, evidence of a holozoic mode of nutrition. The periplast
of the body is double contoured in Schiitt’s figure. Color?

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 325

Drmenstons.—Length, 28; transdiameter, 20H; axes of nucleus, about 10
and 6.

OccuRRENCE.— Figured by Schiitt (1895) from material of the Plankton
Expedition from the Atlantic or Bay of Naples.

SynonyMy.—The name Gymnodinium ovum as applied to this species by
Schiitt is now inapplicable, as the organism presents the Gyrodinium type of
girdle.

Comparisons.—This species belongs with two other rather small, broadly
ellipsoidal, non-striate marine species, G. capsulatum sp. nov. and G. foliacewm
nom. sp. nov. (figs. CC, 14,18). It is smaller than either of these, has relatively
more displacement of the girdle and greater antapical asymmetry. It lacks
the apical point found in G. foliacewm.

Gyrodinium parvulum (Schiitt)
Text figure CC, 4
Gymnodinium parvulum Sehiitt (1895), pl. 25, fig. 84.

DraGnosis.—A minute species with subovoidal body, its length 2.2 transdi-
ameters; girdle a descending left spiral, displaced 0.88 transdiameter; sulcus
(?). Length, 33. Atlantic (?) or Bay of Naples.

Description.—The body is subovoidal, widest anteriorly and tapering at both ends, its length
2.2 transdiameters at the widest part, which is at the girdle. The hypocone exceeds the epicone
in size, being nearly three times as large. The epicone is short, conical (90°) anteriorly with a
blunt apex. Its length on the left and right sides is 0.20 and 0.36 respectively of the total length
of the body. The hypocone is more tapering and slightly narrower at the antapex, which is
without suleal notch.

The girdle begins at a distance from the apex of 0.2 of the total length of the body. It
follows a descending left spiral course around the body and terminates at a distance from the
apex of about 0.4 of the total length of the body. The furrow is wide, about 0.23 transdiameter,
and deeply impressed with overhanging borders. The sulcus and flagella are not shown in
Schiitt’s (1895) figure.

The nucleus is an ellipsoidal body found in the anterodorsal part of the organism. Its major
and minor axes are about 0.8 and 0.4 transdiameter in length respectively. It is densely filled
with coarse chromatin strands. Two large brownish food masses occupy the posterior part of
the body. The remainder of the cytoplasm is thickly strewn with vacuoles of varying sizes.

Diwensions.—Length, 33; transdiameter, 154; axes of nucleus, about 12
and 6.

OccurRENCE.—A single specimen of this species has been recorded by Schitt
(1895) from collections made by the Plankton Expedition from the Atlantic
or the Bay of Naples.

ComParisons.—This species is nearest G. pusillum (Schilling and G. hyali-
num (Schilling), both fresh-water species of smaller size and relatively larger
epicone.

326 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Gyrodinium pepo (Schiitt)
Text figure DD, 2

Gymnodinium spirale var. pepo Schiitt (1895), p. 112, pl. 21, figs. 69,,.
Spirodinium spirale var. pepo, Lemmermann (1899), p. 359.

DraGnosis.—A medium sized species with ovoidal flask-shaped body with
contracted curved apex, its length 1.6 transdiameters; girdle a descending left
spiral, displaced 0.54 transdiameter; sulcus extending from apex to antapex,
surface coarsely striate. Length, 81. Atlantic (?) or Bay of Naples.

DescripTioN.—The body is stout ovoidal, widest posteriorly and tapering anteriorly, its
length 1.6 transdiameters at the widest part, which is in the middle of the hypocone. The
epicone is slightly longer than the hypocone, but is much narrower. It has a length on the left
and right sides of 0.39 and 0.7 respectively of the total length of the body. The epicone contracts
towards the apex which is deflected towards the left side of the body with the left side of the
epicone concave and the right side convex. The hypocone is hemispherical behind the girdle
region with broad, smoothly contoured antapex.

The proximal junction of the girdle and suleus occurs at 0.39 of the total length of the body
from the apex. It sweeps around the body in a descending left spiral course and joins the sulcus
distally about 0.7 of the total length of the body from the apex, having a displacement of 0.54
transdiameter. The furrow is wide, 0.08 transdiameter, and deeply impressed with smooth
borders. The suleus begins near the apex and extends posteriorly to within a short distance of
the antapex. The transverse flagellum arises at the anterior junction of the girdle and sulcus
and traverses the entire length of the girdle. The longitudinal flagellum arises slightly below
the posterior junction of the sulcus and girdle.

The nucleus is broadly ellipsoidal, and is located in the anterior part of the body. Its major
and minor axes are about 1.56 and 0.40 transdiameters respectively. Coarse chromatin strands
fill the body of the nucleus. <A large pusule is found in the posterior part of the hypocone, but
its connection with the posterior flagellar pore is not indicated. The cytoplasm is filled with
large vacuoles, closely crowded together. In the peripheral layer are minute spherules, longi-
tudinal, equidistant and about equal in number on both epicone and hypocone, about 24 across
the ventral face. Color?

Dimensions.—Length, 81; transdiameter, 50“; axes of nucleus, 284 and 20+.

OcCCURRENCE.—Figured by Schutt from the collections of the Plankton
Expedition from the Atlantic or the Bay of Naples. A single specimen was
taken, 1.25 miles off La Jolla, California, July 25, 1906, with a No. 20 net, ina
surface haul.

SynonyMy.—This species was figured by Schiitt as Gymnodinium spirale
var. pepo, and later changed by Lemmermann (1899) to Spirodinium spirale
var. pepo. It has none of the characteristics of spirale, however, lacking the
slender fusiform shape of body, the wider displacement of the girdle, and the
slight torsion of the sulcus and body of that species. It cannot thus be consid-
ered a variety of that species and we therefore propose for it species rank, as
G. pepo.

Comparisons.—This species has the most rotund inflated hypocone found in
the genus. This feature, together with the curved apex, differentiates the

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 327

species from all others in the genus. The nearest approach to it is found in
G. lachryma (Meunier), a much more attenuate and slender species, whose
surface structure 1s unknown.

Gyrodinium pingue (Schiitt)
Plate 4, figure 38; text figure DD, 15

Gymnodinium spirale var. pingwis Sehiitt (1895), pl. 21, fig. 65.
Spirodinium spirale var. pingue, Lemmermann (1899), p. 359.

Dracnosts.—A small species with elongated ovoidal body, its length 1.58
transdiameter; girdle a descending left spiral, displaced 0.74 transdiameter ;
suleus extending from near apex to antapex; surface finely striate; color, pale
lumiere green. Length, 514. Pacifie off La Jolla, California, July; Atlantic
or Bay of Naples.

DescripTion.—The body is ovoidal, cireular in cross-section, broadly rounded posteriorly,
narrowly so anteriorly, its length 1.88 transdiameters at the widest part in the upper hypocone.
The hypocone exceeds the epicone in size, having a continuously broader transdiameter, though
the lengths are approximately the same. The epicone is convex conical, forming an angle of
about 70°, with a blunt apex. It has a length on the left and right sides of 0.25 and 0.66
respectively of the total length of the body. The hypocone is elongate hemispherical posteriorly
with a broad antapex. It has a length on the left and right sides of 0.68 and 0.27 of the total
length of the body.

The girdle is a descending left spiral with its proximal and distal ends joining the sulcus at
a distance from the apex of 0.25 and 0.66 respectively of the total length of the body. In the
first 0.5 transdiameter of its course its direction is slightly deflected anteriorly, turning poster-
iorly on the dorsal surface and continuing on the ventral surface in a steep spiral with its distal
end displaced 0.74 transdiameter. The furrow has a width of about 0.09 transdiameter, and is
deeply impressed with smoothly rounded borders. The sulcus extends from or near the apex
posteriorly to the antapex in a slightly sinuous line. Its width is about half that of the girdle
and is rather shallow, fading out near the antapex.

The nucleus is spherical in shape and is located at or near the center of the body. It is filled
with fine moniliform chromatin strands. Its axis is about 0.4 transdiameter in length.

A large, sacklike pusule opens into the posterior flagellar pore, and is sometimes present at
both pores. The cytoplasm is usually dense and alveolar in structure, often containing many
inclusions, such as greenish refractive spherules, blue-green oil droplets and larger food masses
indicative of holozoic nutrition. A peripheral zone of short, blue-green rodlets is often present.
The color of the cytoplasm is pale lumiere green diffused throughout. The surface is finely
striate, the striae varying somewhat in different individuals. In most of the specimens examined
these consist of blue-green, equidistant lines. In other forms the lines may be broken by minute
blue-green granules strung along their length like beads on a thread or giving the appearance of
a dot and dash (pl. 4, fig. 38).

Dimensions.—Leneth, 45-51; transdiameter, 30-27; axis of nucleus, 11.
OccurRENCE.—This was first recorded for this region July 13, 1906, in a
surface haul taken with a No. 20 net near La Jolla, California. On July 19,
1906, it was again found in a surface haul. It was frequently seen during July
and August, 1917, both in the surface hauls made at the end of the pier at the

328 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Biological Station at La Jolla and in the hauls made 4 and 6 miles offshore
from 80 meters to the surface.

Tt was first figured by Schutt (1895) from the material of the Plankton
Expedition, presumably from the Bay of Naples or the Atlantic.

SynonyMy.—Originally figured by Schtitt (1895, pl. 21, fig. 65) as Gymno-
dinium spirale var. pinguis, but later assigned to Spirodinium by Lemmermann
(1899). Specific rather than varietal status for this form is indicated by its
stouter fusiform shape, lack of torsion of the body, and heavy peripheral layer
of rodlets, all of which characters distinguish it from G. spirale.

CoMParIsons.—This species is close to G. ovoideum in size and proportions,
but is green instead of yellow and has less torsion, displacement of girdle and
asvmmetry.

Gyrodinium postmaculatum sp. noy.
Plate 6, figure 64; plate 8, figure 91; text figure DD, 20

DrtaGnosis.—A medium sized species with obovoidal body, its length 1.86
transdiameters; girdle a descending left spiral, displaced 0.66 transdiameter ;
sulcus extending from apex to antapex; surface striate with broken lines; color,
amaranth purple. Length, 86+. Pacific off La Jolla, California, July, August.

DescripTioN.—The body is stout obovoidal to ellipsoidal in outline, rounded anteriorly, more
tapering posteriorly, circular in cross-section, its length 1.86 transdiameters at the widest part,
which is in the upper third of the hypocone. The hypocone exceeds the epicone in size, its length
being greater by 0.09 of its own length. The epicone is elongate hemispherical anteriorly, its
sides subparallel posteriorly, with the apex sometimes projecting slightly above the surrounding
surface. It has a length on the left and right sides of 0.25 and 0.63 respectively of the total
length of the body. The hypocone is rounded anteriorly, tapering to a slender point posteriorly.
It has a length on the left and right sides of 0.7 and 0.36 respectively of the total length of the
body. Its transdiameter anteriorly is greater than that of the epicone and its sides are more
convex, and the antapex may be metabolic. It often forms a more or less acute antapieal point.

The girdle is premedian for most of its course. Its proximal end joins the suleus at a distance
from the apex of 0.25 and its distal end 0.63 respectively of the total length of the body. Its
course about the body for the first 0.5 of its length is in a nearly transverse direction, beyond
which it turns posteriorly at a gradually steepening angle which becomes about 40° with the
longitudinal plane of the body, at its junction with the girdle, with a displacement of 0.66
transdiameter. The furrow is narrow, having a width of about 0.02 transdiameter, and is deeply
impressed with smoothly rounded edges. The suleus reaches the apex where it forms a slightly
enlarged, rounded pit, with its proximal border slightly raised above the surrounding surface.
It extends posteriorly as a deep trough in a nearly straight line to within a short distance of the
antapex, where it fades out. Its width is variable, narrowed anteriorly, enlarging at the anterior
pore to about twice the width of the girdle, and becoming narrower again beyond the posterior
pore. The anterior flagellar pore opens at the proximal junction of the girdle and suleus, the
posterior pore a short distance beyond the distal junction.

The nucleus is a large, spheroidal body filled with coarse, moniliform chromatin strands. It
is slightly premedian in position, lying dorsad to the anterior flagellar pore. Its axis is about
0.52 transdiameter in length.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 329

A large, sacklike pusule opens into the anterior flagellar pore and another, slightly smaller,
into the posterior pore. The cytoplasm is finely granular and alveolate in structure and often
contains one or more food masses. The body sometimes contains numerous large vacuoles filled
with a fluid, colored pink like that in the pusules. Seattered profusely in its surface are minute
green circles which seen in side view are the ends of small, slender, blue-green rodlets or rhabdo-
somes, arranged at right angles to the surface in a peripheral zone. The color of the body is
amaranth purple condensed in a thin layer immediately beneath the periplast (pl. 8, fig. 91).
This same coloring matter is generally collected in a denser mass at the antapex. The color
may vary to something nearer a rosy tint as in figure 64, plate 6. The surface is striated with
broken lines showing an amaranth purple color. On the epicone the striae are about 2.54 distant
from each other at the girdle and on the proximal part of the hypocone about half that width,
thus making the number on the hypocone nearly twice that on the epicone. There are about
20 across the ventral face on the epicone.

Divenstons.—Length, 52-86; transdiameter, 30-454; transdiameter of
nucleus, 16-22».

-OccuRRENCE.—This was first taken July 9, 1904, with a No. 12 silk net, in
a surface haul, 7 miles off Point Loma, California. It was taken again July 18,
1917, with a No. 25 silk net, in a surface haul, 4 miles off La Jolla, California,
in a surface temperature of 20°2 C. It occurred also on July 20 and 23 in hauls
made 6 miles off La Jolla from 20 and 80 meters to the surface respectively and
in surface temperatures of 21°5 C and 20°8 C.

CoMPARISONS.—This species, with its peripheral zone of rodlets, resembles
G. fissum (fig. DD, 8) and G. obtusum (fig. DD, 3). In its coloring of amaranth
purple it is unlike any other species of Gyrodinium, its nearest approximation
being found in Pouchetia purpurata (pl. 8, fig. 87). The localization of the
color in the peripheral layer is similar to the condition in Pouchetia voracis
(pl. 8, fig. 89). As in many other species of the Gymnodiniidae, the colored
pigment shows here also a strong tendency to collect at the apices. The local-
ization of the pigment in the antapex, the interrupted striae, and the size are
quite similar to these features in G. rubricaudatum sp. nov. (fig. DD, 18), but
the more rotund body and the purple instead of red color differentiate the two.

Gyrodinium pusillum (Schilling)
Text figure CC, 3
Gymnodinium pusillum Schilling (1891a), p. 60, pl. 3, fig. 15; (1891b), p. 201; Spiro-
dintum pusillum, (1913), pp. 21-27, fig. 22.
G. pusillum, Mez (1898), p. 216.
G. pusillum, Schonichen and Kalberlah (1900), p. 281; (1909), p. 252.
G. pusillum, Massart (1901), p. 82.
G. pusillum, Ohno (1911), p. 91.

Dracnosis.—A minute species with obliquely asymmetrical ellipsoidal body,
its length 1.5 transdiameters; epicone obliquely sloped to the right; girdle a
descending left spiral, displaced about 0.3 transdiameter ; sulcus extending from
girdle to antapex; yellow chromatophores. Length, 234. Fresh-water swamps
near Basel, Switzerland.

330 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Description.—The body is asymmetrical ellipsoidal, broadest in the middle and rounded at
the apices, its length 1.5 transdiameters at the widest part. The hypocone exceeds the epicone
in size, its length being greater by 0.22. The epicone is broad and rounded with a length on the
left and right sides of 0.19 and 0.53 of the total length of the bedy. It slopes obliquely to the
right. The hypocone is rounded on the right side with the antapex and left side sloping
obliquely towards the girdle on the left side.

The girdle begins near the anterior end of the body at a distance from the apex of 0.19 of
the total length of the body. It follows a descending left spiral course around the body, dis-
placed posteriorly on the right side about 0.3 transdiameter. The furrow is wide, about 0.18
transdiameter, and is deeply impressed with overhanging borders. The suleus extends from the
girdle to the posterior end, but is omitted from Schilling’s (1891a, 1913) figures. The transverse
flagellum traverses the entire length of the girdle. The longitudinal flagellum arises near the
distal end of the girdle.

Nucleus and pusules are not figured for this species. The peripheral zone of cytoplasm is
filled with large, round, disklike, light yellow chromatophores. A carmine-colored stigma is
present in the suleal region below the insertion of the longitudinal flagellum.

Divensions.—Length, 234; transdiameter, 18.44 is given by Schilling
(18917) in the text, but his figures have a width of about 154. This dimension
has been used in the above description.

OccURRENCE.—Figured by Schilling (1891a@) from the swamps in the neigh-
borhood of Basel, Switzerland. The only other record of its occurrence is that
by Massart (1901) in brackish ditches around Palingbrug, Belgium.

SynonyMy.—Originally described by Schilling as Gymnodinium pusillwm
and later transferred by Lemmermann (1899, 1903) to Spirodinium, an allo-
cation followed by Schilling in his monograph of German fresh-water dino-
flagellates (1913).

Comparisons.—This species, with G. hyalinwm, are the only representatives
of Gyrodinium thus far described from fresh water. It is also one of the four
species of the genus with chromatophores. It greatly resembles G. hyalinum,
differing from it mainly in the possession of chromatophores.

Gyrodinium rubricaudatum sp. noy.
Plate 10, figure 116; text figure DD, 18

DiaGnosis.—A medium sized species with symmetrically ellipsoidal to
biconical body, its length 2.16 transdiameters, girdle submedian, a descending
left spiral displaced 0.44 transdiameter ; sulcus extends from near apex to near
antapex; surface with broken striae; color, greenish yellow with coral-red pig-
ment. Length, 984. Pacific off La Jolla, California, July, August.

DescripTion.—The body is symmetrically ellipsoidal, approaching biconical, in outline, cir-
cular in cross-section, tapering towards both apices, its length 2.16 transdiameters at the widest
part. The hypocone is slightly larger than the epicone in size, its length being greater by 0.08
of its own length. The epicone is convex-conical (50°) in outline with narrow, blunt apex. It
has a length on the left and right sides of 0.36 and 0.58 respectively of the total length of the
body. The hypocone has a slightly greater transdiameter and its sides are more convex than
those of the epicone. The posterior end is prolonged into a short club-shaped projection at the
antapex. The length of the hypocone on the left and right sides is about 0.62 and 0.45 respec-
tively of the total length of the body.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 33]

The girdle is slightly premedian in position, its proximal end joining the sulcus at a distance
from the apex of 0.36 and its distal end 0.56 of the total length of the body. It sweeps around
the body in a nearly transverse direction for 1.5 transdiameters before it is deflected posteriorly
at an angle of about 35° with the transverse plane, meeting the girdle with a displacement of
0.44 transdiameter. The furrow is rather narrow, its width being about 0.04 transdiameter, it
is deeply impressed with the coneavity undereutting the anterior lip and gradually curving out
at the posterior one. The suleus begins near the apex and passes posteriorly in a sinuous line
to near the antapex. Its width is slightly greater than that of the girdle and it is relatively
deep, fading out near both apices. The anterior flagellar pore opens in the suleus just anterior
to its proximal junction with the girdle, the posterior pore at the posterior junction.

The nucleus is a rather large ellipsoidal body, located anterocentrally. Moniliform chromatin
strands follow diagonally across its longer axis. Its major and minor axes are 0.7 and 0.2
transdiameter in length respectively.

The cytoplasm is finely granular, clear and transparent, greenish yellow in color, and usually
free from cell inclusions, such as food bodies. The surface is striate with blue-green striae of
short dashes arranged in linear series. There are about twice as many of these on the
hypocone as on the epicone, where there are about 24 across the ventral face. Our figure (DD, 18)
inadequately portrays this contrast. At the antapex is a mass of coral-red pigment oceupying
the club-shaped projection of the body and extending more or less into the lower part of the
hypocone.

Dimensions.—Length, 93; transdiameter, 43; axes of nucleus, 284 and 22.

OccuRRENCE.—This was taken July 17, 1906, with a No. 8 silk net, in a
surface haul 1.5 miles off La Jolla, California, in a surface temperature of
21°9 C. It was quite abundant in the hauls made between July 27 and August
21, 1917, in both surface and deeper hauls. The number of individuals noted
in a short examination ranged from one to seventeen in a single catch.

CoMPARISONS.—This species affords the most striking example of the antap-
ical location of its pigment, the entire amount present in the body being here
concentrated in the antapex. The more common condition among the pigmented
species of Gyrodinium is the presence of pigment in the anterior part of the
body, with a scant amount, if any, in the antapical region, as in G. maculatwin
(pl. 6, fig. 62). In G. postmaculatum (pl. 6, fig. 64) an intermediate condition
is shown, with a localized antapical pigment mass and also pigment diffused
throughout the periphery. G. rubricaudatum leads onwards to the greater
development of the same tendency in Pavillardia (pl. 10, fig. 114), where there
is localization of the pigment in the mobile posterior tentacle.

Gyrodinium schuetti Lemmermann
Text figure DD, 5

Gymnodinium cornutum Sehiitt (1895), p. 113, pl. 22, fig. 71.
Spirodinium schuetti, Lemmermann (1899), p. 359.

Draanosis.—A large species with broadly ellipsoidal body, its length 1.95
transdiameters; girdle a descending left spiral, displaced 0.83 transdiameter ;
suleus extending from near apex to antapex; surface finely striate. Length,

117. Atlantic (?) or Bay of Naples.

332 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

DescriptioN.—The body is broadly ellipsoidal with broad apices, circular in cross-section, its
length 1.95 transdiameters at the widest part. The epicone and hypocone are subequal in size.
The epicone is elongate hemispherical in shape with broad, symmetrically rounded apex. It
has a length on the left and right sides of the body of 0.42 and 0.67 respectively of the total
length of the body. The hypocone in Schiitt’s figures presents a metabolic appearance poster-
iorly. This is probably due to the recent ejection of a food mass, as we have frequently observed
the same appearance in Gymnodinium heterostriatum following the ejection of a food body when
first placed under a cover slip under the microscope. In a short time the thus modified posterior
part resumes its normal rounded appearance.

The girdle is a descending left spiral with a distance from the apex at its proximal and distal
ends of 0.42 and 0.67 respectively of the total length of the body. The furrow has a width of
about 0.06 transdiameter, becoming narrower at its distal end, and is rather shallow, with smooth,
overhanging borders. The suleus extends from the apex to the antapex in a slightly sinuous line.
The transverse flagellum arises at the proximal junction of the girdle and sulcus, the longitudinal
flagellum midway between the distal junction and the antapex.

The nucleus is a large ellipsoidal body. filled with parallel moniliform chromatin strands,
and lying in the anterocentral part of the body, oblique to the longitudinal axis. Its major and
minor axes are about 0.73 and 0.48 transdiameter in length respectively. The anterior end of
the body is filled with large alveoli. The surface of the body is closely beset with longitudinal,
beaded striae, nearly equal in number on both epicone and hypocone, about 30 across the ventral
face. Color (?).

DiMeEnsions.—Length, 117; transdiameter, 60; axes of nucleus, 44» and 29+.

OccURRENCE.—Figured by Schiitt (1895) presumably from material of the
Plankton Expedition from the Atlantic or from the Bay of Naples.

SynonymMy.—This organism was described by Schutt as Gymnodinium
cornutum n. sp., a name which was preoccupied by Pouchet (1885@) in his G.
cornutum (=Gyrodinium cornutum (Pouchet) Kofoid and Swezy); it was
later changed by Lemmermann (1899) to Spiredinium schuetti.

Comparisons.—The only other species of Gyrodinium with striae and a
rotund epicone are G. truncus sp. nov., G. grave (Meunier), G. pingue (Sehiitt),
G. maculatum sp. nov., and G’. postmaculatum sp. nov. (figs. DD, 4, 7, 15, 19, 20).
G. truncus is more rotund, with shorter epicone and fewer striae; G. grave isa
smaller species with much more displacement and torsion of girdle; G. pingue
is a smaller species with more slender body and relatively greater displacement ;
G. maculatum is much smaller, is pigmented, and has more intercingular
torsion; and G. postmaculatum has a pointed pigmented antapex.

Gyrodinium spirale (Bergh)
Plate 4, figure 43; text figure DD, 14

Gymnodinium spirale Bergh (1881a), p. 66; (18816), pp. 253-255, pl. 16, figs. 70, 71.

G. spirale, Saville-Kent (1880-1882), p. 858.

G. spirale, Pouchet (1883), pp. 446, 447; (1885@), pp. 44, 67-69, pl. 4, fig. 30.

G. spirale, Daday (1884), p. 18, fig. 4.

G. spirale, Klebs (1884), p. 730; (1912), pp. 429, 480.

Spirodinium spirale, Entz, Sr. (1884), p. 39; Entz, Jr. (1902a), p. 92; (1902b), p. 119;
(1905), p. 108; (1907), pp. 17, 24; (1909), pp. 254, 255.

Gymnodinium spirale, Biitschli (1885), pp. 965, 974, 975, 993, 1017, 1018, pl. 51, fig. 5.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 333

G. spirale, Schilling (1891), pp. 200, 205, 206.

G. spirale, Whitelegge (1891), pp. 181, 188, pl. 28, fig. 8.

G. spirale, Schiitt (1895), pp. 35, 37, 95, 113, 117; as Spirodinium spirale (1896), p. 5,
fig. 6.

G. spirale, Delage and Hérouard (1896), p. 354, fig. 666.

G. spirale, Jorgensen (1899), p. 26.

Spirodinium spirale, Lemmermann (1899), p. 339; (1901), p. 358; (1902), p. 260.

S. spirale, Schroder (1900), p. 13; (1911), pp. 620, 626, 651.

S. spirale, Pavillard (1905), p. 47.

Gymnodinium spirale, Dogiel (1906), pp. 40, 41, 43.

G. spirale, Karsten (1907), p. 335.

Spirodinium spirale, Paulsen (1907), p. 24; (1908), pp. 101, 102, fig. 140.

Gymnodinium spirale, Franeé (1908), p. 48.

G. spirale, Doflein (1909), p. 461, fig. 412; (1911), p. 527, fig. 472,.

G. sptrale, Herdman (1911b), p. 72; (1911c), p. 40.

Spirodinium spirale, Schiller (1912), p. 28.

S. spirale, Cavers (1913), pp. 182, 183, fig. 9,,. :

S. spirale, Ostenfeld (1913), pp. 123, 338, 344, 476.

S. spirale, West (1916), p. 51, fig. 36c.

S. spirale, Lebour (1917b), p. 193, fig. 10a.

DraGnosis.—A medium sized species with fusiform body, its length 2.5 trans-
diameters; girdle a descending left spiral, displaced 1.19 transdiameters ; sulcus
extending from apex to antapex; surface striate; color, ivory yellow. Length,
105» to 150#. Cosmopolitan marine habitat.

DescripTion.—The body is slender fusiform, widest posteriorly, tapering anteriorly, nearly
circular in cross-section, its length 2.5 transdiameters at the widest part. The dorsal side is
convex, the ventral subeoneave, giving both apices a slight ventrad deflection and the whole body
a small degree of asymmetry, which is most noticeable in lateral view. The greatest length of
the hypocone is somewhat less than that of the epicone, but its size is greater, due to its con-
tinuously greater transdiameter. The epicone has the shape of a cone of about 40°, convex on
the left and dorsal sides and becoming coneave on the right and ventral sides. The apex is blunt.
It has a length on the left and right sides of 0.3 and 0.76 respectively of the total length of the
body. The sides of the hypocone are subparallel anteriorly, rounded posteriorly, deeply notched
on the left side of the antapex by the distal end of the suleus, with the right side forming a
rounded lobe extending 0.19 transdiameter beyond the left.

The girdle is a steeply descending left spiral with a displacement of 1.19 transdiameters or
0.47 of the total length of the body. Its proximal end joins the sulcus at a distance from the
apex of 0.3 and its distal end 0.76 of the total length of the body, with an overhang of about
0.19 transdiameter. The furrow has a width of about 0.08 transdiameter and is deeply impressed
with smooth borders which are generally undereut and somewhat elevated above the surrounding
surface. The sulcus extends from the apex to the antapex with a torsion of about 0.19 trans-
diameter. Its width is about half that of the girdle in the intercingular area, narrower anteriorly
and widening somewhat posteriorly where it excavates the left side of the antapex. The anterior
flagellar pore opens at the proximal junction of the girdle and suleus, the posterior pore about
one width of the girdle below the distal junction.

The nucleus is ellipsoidal to spheroidal in shape and is situated in the anterocentral part of
the body. It is filled with fine moniliform, subparallel chromatin strands. Its major and minor
axes are about 0.47 to 0.71 (to 0.56 transdiameter in the spheroidal form) in length.

Small sacklike pusules may be present at either pore or at both. In the individual figured
the posterior pusule was very large and the anterior one absent. The cytoplasm is very finely

334 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

granular, clear and transparent, and often contains large vacuoles and food masses, evidences of
a holozoie mode of nutrition. The surface is beset with equidistant, longitudinal, blue-green
striae which are about twice as numerous on the hypocone as on the epicone, which has about 15
across the ventral face. The general color of the organism varies from pale, glaucous green to
ivory yellow.

Dimensions.—Length, 105-1507; transdiameter, 40-45; axes of nucleus, 20
and 30 to 244 and 24.

OccURRENCE.—Our first record for this species is June 3, 1907, 2.25 miles
off La Jolla, California, in a haul from 120 meters to the surface. On July 18,
1917, it was found in a surface haul at the end of the pier at the Biological
Station and on July 20 in a haul 6 miles offshore from 80 meters to the surface
and a surface temperature of 21° C.

It was first figured by Bergh (1881) from the Baltic Sea. Other records
of its occurrence are as follows: Pouchet (1883-1885a) in the Atlantic off
Conearneau, France, in October; Entz, Jr. (1902) in the Adriatic Sea; White-
legge (1891), Port Jackson, Sydney, Australia, in April and May; Jorgensen
(1899), in the Atlantic off Puddefjord, and Hardangerfjord, Norway, in April
and July; Schréder (1900) in the Gulf of Naples (1911) and Adriatic Sea, in
July; Pavillard (1905) in the Gulf of Lyons in October; Karsten (1907) in
the Indian Ocean, 1° 40‘6 S, 41° 47:1 E, in March; Herdman (1911) at Port
Erin, Isle of Man; Ostenfeld (1913) in Baltic Sea off coast of Denmark, July,
August; and Lebour (1917)) at Plymouth Sound, England.

SynonyMy.—This species was originally described by Bergh (1881) as
Gymnodinium spirale and later utilized by Schutt (1896) as the type species
of his genus Spirodinium. Pouchet (1883) has characterized five varieties of
this species, of which he names only two, G. spirale var. nobilis and G. spirale
var. striatum. The characters given to these are such that it is not possible to
reidentify them. His variety D is probably Gymnodinium heterostriatum.

Compartisons.—This is the type species of the genus Gyrodinium, following
Schiitt’s use of it as his type species in his genus Spirodinium, which it replaces.
Tt also is the type of the subgenus Gyrodinium. In the torsion and shape of
the body it resembles G. biconicum, but is distinct from it in the presence of
surface striae. In the overhang of the girdle and the slight amount of torsion
in the intercingular sulcus it looks forward to the next genus, Cochlodinium.

Our figures show a stouter body with less contraction at the apices than do
Bergh’s (1881)) ; but our material includes forms as slender as he has figured,
though these are less typical of the species as we find it.

Gyrodinium spumantia sp. nov.

Plate 7, figure 72; text figure CC, 13
Dracnosis.—A large species with irregularly obovoidal body, its length 1.8
transdiameters; girdle a descending left spiral, displaced 0.43 transdiameters ;
sulcus extends from apex to antapex; color, pink, grey and yellow ochre.

Length, 1464. Pacific off La Jolla, California, August.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 335

DeEscrIPTION.—The body is irregular, asymmetrical obovoidal in outline, its broadest trans-
diameter premedian, its length 1.8 transdiameter at the widest part, which is at the girdle. The
entire outline of the body is uneven and ridged, but without wrinkling of the pellicle resulting
from shrinkage. The size of the hypocone is somewhat greater than that of the epicone, its
length being greater by 0.13 of its own length. The shape of the epicone is roughly conical
(50°) with irregular metabolic sides. It has a length on the left and right sides of 0.32 and 0.56
respectively of the total length of the body. The apex is blunt and notched by the suleus. The
hypocone is somewhat narrower (35°) than the epicone, also irregular in outline, with a more
slender, pointed antapex. Its length on the left and right sides is about 0.65 and 0.43 respectively
of the total length of the body.

The girdle is premedian for the greater part of its length. Its proximal end joins the sulcus
at a distance from the apex of 0.32 and its distal end 0.56 of the total length of the body. The
first 0.5 transdiameter of its course follows a nearly transverse direction around the body, beyond
which it is deflected posteriorly in an increasingly steeper angle, its distal end being displaced
about 0.43 transdiameter. The furrow is narrow, its width being about 0.03 transdiameter, and
is deeply impressed with overhanging borders.

The suleus extends from the apex to the antapex as a shallow, narrow trough. Its direction
is that of a sigmoid curve anteriorly, less sinuous posteriorly. The anterior flagellar pore opens
at the proximal junetion of the girdle and sulcus, the posterior pore midway between the distal
junction and the antapex.

The nucleus is spheroidal and situated in the right central part of the body. It is filled with
coarse chromatin strands. Its axis is about 0.3 transdiameter in length.

A small sacklike pusule opens into each flagellar pore. The eytoplasm presented a foamy
appearance with finely granular constituency and was completely filled with large vacuoles
containing a pink fluid, with blue-green droplets and dark, refractive granules. These were so
massed together as to give the body a dense appearance and without sharp contrast in its various
parts. The basal color of the cytoplasm is pearl grey with minute dots of yellow ochre which
become dense in the girdle region, the anterior part of the suleus and at the antapex. A thick
cluster of melanin granules was present in the apical region on the right side of the sulcus.
There were no striations or other surface markings.

Dimenstons.—Length, 146; transdiameter, 81; axis of nucleus, 26+.

OccuRRENCE.—A single individual was taken August 21, 1917, with a No. 25
silk net, 5 miles off La Jolla, California, in a haul from 83 meters to the surface.

Compartsons.—In the foamlike structure of its cytoplasm, which may, how-
ever, be only a transient metabolic condition, this species resembles G. flavidum
(pL 7, fig. 73) and Gymnodinium multistriatum (pl. 4, fig. 87), without the firm
pellicle of the latter species. It is the only species in the genus showing the
presence of melanin which is common in the more highly specialized genera,
Pouchetia and Erythropsis. This may have come from ingested food. Its
labile body is unique in Gyrodinium.

Gyrodinium submarinum sp. noy.
Plate 10, figure 110; text figure DD, 1
DiaGnosis.—A large species with slender fusiform body, its length 3.54
transdiameters; girdle a descending left spiral, displaced 1.75 transdiameters ;
sulcus extending from apex to antapex; surface striate; color, dull glaucous
blue. Length, 117+. Pacific off La Jolla, California, July.

336 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

DescripTion.—The body is long, slender fusiform, circular in cross-section, tapering towards
both ends, but slightly truncate posteriorly, its length 3.54 transdiameters at the widest part,
which is near the middle. The epicone and hypocone are subequal, though the posteriorly
extending point on the right ventral side gives to the epicone a slightly greater length. The
epicone is convex conical (45°) anteriorly with a pointed apex, but posteriorly its sides are
subparallel with only a sight convexity. It has a length on the left and right sides of 0.27.and
0.76 respectively of the total length of the body. The hypocone is convex conical with a greater
transdiameter posteriorly than the corresponding part of the epicone, with the antapex obliquely
truncate on the right side of the suleal notch. Its sides are slightly more convex than those of
the epicone.

The girdle is a steeply descending left spiral, its proximal end joining the suleus at a distance
from the apex of 0.27 and its distal end 0.76 of the total length of the body, giving it a dis-
placement of 1.75 transdiameters or about 0.5 of the total length of the body. The furrow has a
width of about 0.07 transdiameter and is deeply impressed on its anterior side, where it under-
cuts the lp, becoming more shallow towards its posterior border. Both lips are smooth and
somewhat protuberant. The sulcus extends from the extreme anterior tip of the body posteriorly
in a slightly sinuous line to the antapex. It is narrow anteriorly, widening slightly in the
intercingular area and again near the posterior end of the body, where it deeply notches the
right side of the antapex. Its greatest width is less than that of the girdle. The anterior
flagellar pore opens at the proximal junction of the girdle and suleus, the posterior pore
immediately posterior to the distal junction.

The nucleus is long ellipsoidal to conform to the shape of the body and is filled with monili-
form chromatin strands lying parallel with its long axis. It is located dorsad of the intercingular
area, near the center of the body. Its major and minor axes are about 1.36 and 0.33 trans-
diameters in length respectively.

A small, sackhike pusule opens into the anterior flagellar pore. The cytoplasm is finely
granular and transparent with numerous yellowish green spherules and oil droplets scattered
through it. <A large refractive body of irregular shape, outlined with a dark border, nearly
filled the apical region in front of the anterior flagellar pore. The antapical region contained a
group of refractive spherules closely massed together and outlined by a dark ring. The color
of the body is a pale dull glaucous blue diffused through the cytoplasm. The surface is closely
beset with numerous, equidistant, longitudinal, blue-green striae, the number on the hypocone
slightly greater than that on the epicone, 25 to 30 across the ventral face.

Dimenstons.— Length, 117; transdiameter, 33; axes of nucleus, 45 and 11+.

OccuRRENCE.—Three individuals were taken July 25, 1917, with a No. 25
silk net, 5 miles off La Jolla, California, in a haul from 80 meters to the surface
and in a surface temperature of 20° C.

Activities.—This is an extremely active form under the microscope, moving
in large loose clockwise spirals with a slow rotation on the long axis. The spiral
is occasionally reversed to the anticlockwise direction.

Compartsons.—In the slender fusiform shape of body this species resembles
G. britannia sp. nov. (fig. DD, 13) and G. acutum (Schutt) (fig. CC, 7), differ-
ing from both, however, in the character of its surface markings and in the
greater displacement of its girdle, and from the former species also in its lack
of pigmentation. It is the most slender and one of the most active species in
the genus.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 33

“|

Gyrodinium truncatum sp. noy.
Plate 1, figure 3; text figure CC, 5

DraGnosis.—A small species with subovoidal body, its length 1.62 transdi-
ameters; girdle submedian, a descending left spiral, displaced 0.4 transdiam-
eter; sulcus short on epicone, extending to antapex on hypocone; color, yellow
green shading to yellow ochre posteriorly. Length, 57. Pacific off La Jolla,
California, July.

DescripTion.—The body is broadly ovoidal or almost biconical, tapering at both ends with
truncate apex, widest posterior to the middle, its length 1.62 transdiameters at the widest part,
which is near the girdle. In cross-section the body is nearly circular. The epicone has a slightly
greater length than the hypocone, but its actual size is about the same. It is truncate conical
of about 60° in shape, contracted towards the apex, and has a length on the left and right sides
respectively of about 0.38 and 0.63 of the total length of the body. The hypocone is rotund
anteriorly, tapering abruptly posteriorly to an acute tip, with the left side more convex than the
right. It has a length on the left and right sides of about 0.57 and 0.33 of the total length of
the body.

The girdle is submedian in position, its proximal end joining the sulcus at a distance from
the apex of 0.38 and its distal end 0.63 of the total length of the body. Its course around the
body is that of a descending left spiral, displaced posteriorly 0.4 transdiameter. The furrow
has a width of about 0.07 transdiameter and is deeply impressed, with a rounded outline, which
undercuts both borders slightly. The suleus invades the epicone for a short distance as a rather
shallow trough and extends posteriorly in a slightly sinuous line which fades out near the
antapex. The anterior flagellar pore is located at the proximal junction of the girdle and sulcus,
the posterior pore midway of the distance between the distal junction and the antapex.

The nucleus is a reniform body filled with moniliform chromatin strands and is found in the
posterior part of the body, in the region of the posterior pore, with its long axis in a transverse
plane. Its major and minor axes are 0.71 and 0.31 transdiameters in length respectively.

A small sacklike pusule opens into each flagellar pore. The cytoplasm is very finely granular,
clear and transparent with a few oil drops scattered through it, and contains a number of food
bodies, evidence of holozoic nutrition. In the anterior portion of the body was a large food mass
yellow grey in color. Near it was a smaller, greenish refractive body and in the antapical
region another one, yellow ochre in color. The general color of the organism is greenish yellow,
shading to yellow ochre posteriorly. A thin-walled, hyaline cyst, somewhat larger than the body,
invested the organism.

Divensions.—Length, 57; transdiameter, 35; axes of nucleus, 21” and 11;
length of cyst, 67+.

OccuRrRENCE.—A single individual was taken July 11, 1917, with a No. 25
net, in a haul 4 miles off. La Jolla, California, from 80 meters to the surface
and in a surface temperature of 19°8 C.

Comparisons.—This is one of the species of Gyrodinium which shows the
nearest approximation to the Gymnodinium type of the girdle arrangement,
and is probably one of the connecting links with that genus. It is one of the
more generalized species in Gyrodinium, and in that respect resembles G. ovum
(Schiitt) and G. foliaceum nom. sp. nov. (figs. CC, 8, 18), lacking, however, the
chromatophores of the latter species.

338 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Gyrodinium truncus sp. nov.
Plate 3, figure 28; text figure DD, 4

Dracnosis.—A large species with body rotund, subellipsoidal, its length 1.48
transdiameters; girdle a descending left spiral, displaced 0.64 transdiameters ;
sulcus extending from apex to antapex; surface coarsely striate; color, greenish
yellow. Length, 834. Pacific off La Jolla, California, August.

DeEscripTION.—The body is large, of robust habit, and asymmetrical outline, its length 1.48
transdiameters at the widest part, which is below the girdle. The posterior end is pointed and
the anterior end is asymmetrical and almost truncate in outline with the girdle region on the
left side forming a high shoulder. A cross-section of the body is nearly circular. The hypocone
greatly exceeds the epicone in size, its length being greater by 0.39 of its own length. The epicone
is somewhat excentric, the left side being raised, forming an angle of 60° with the longitudinal
axis of the body and terminating in a high, shoulder-like ridge about 0.09 of the length of the
body below the apex. The epicone lengthens until it reaches 0.54 of the total length of the body
on the right side of the sulcus. The apex is broad and truncate in outline. The hypocone is
very broad with rounded sides which contract abruptly to a poimt at the antapex, which is
notched on the left side by the distal end of the suleus.

The girdle is a descending left spiral, which meets the suleus proximally about 0.09 of the
total length of the body below the apex. Its distal junction with the suleus occurs at 0.54 of
the total length of the body below the apex, giving it a displacement of 0.64 transdiameters.
It lies in a wide, deep depression, its width about 0.05 transdiameter, with smoothly rounded,
overhanging borders, both of which are undereut by the furrow. The anterior flagellar pore
is located at the anterior junction of the girdle and sulcus and the posterior pore far posterior,
less than 0.2 transdiameter from the antapex. The transverse flagellum was short, traversing
but a short proximal section of the girdle.

The suleus extends from the apex to the antapex. Below the anterior flagellar pore it lies
in a shallow trough with overhanging sides, the borders of which are unevenly serrate, the right
border extending beyond the left in a flap which obscures the furrow.

The nucleus is large, ellipsoidal and situated slightly below the central portion of the body,
with its long axis oblique to that of the body. Large, moniliform chromatin threads follow its
major axis. Its major and minor axes are 0.71 and 0.5 transdiameters in length respectively.

A small sacklike pusule opens into each flagellar pore. The cytoplasm is very finely granular,
and contains food bodies and other evidences of holozoic nutrition. In the individual figured
two large, irregular-shaped, yellowish green and greyish green food bodies were found close
beside the nucleus. In the epicone were three groups of dark, refractive oil globules. Smaller
blue-green oil droplets were scattered through the anterior half of the body. The general color
of the protoplasm is yellowish green in the anterior portion of the body shading to a yellow
ochre and old gold in the antapical region. The surface of the body is striate with blue green,
equidistant lines extending from the girdle to the apices, 15 in number across the ventral face
of the epicone. These are about Ty apart on the epicone and 4 on the hypocone side of the
girdle.

Dimenstons.—Length, 83; transdiameter, 554; axes of nucleus, 42e and 27.

OccURRENCE.—A single individual was taken August 17, 1917, with a No. 25
silk net, 0.75 mile off La Jolla, California, in a haul from 80 meters to the
surface and in a surface temperature of 21°9 C.

Comparisons.—In the unusual asymmetry of the body this form closely
resembles G. flavidum sp. nov. (fig. CC, 20), differing from it, however, both in

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 839

color and in its surface markings, the latter being entirely absent in G. flavidum.
There is a difference between the two in their apices, which are much more
developed in G. flavidwm than in G. truncus.

Gyrodinium virgatum sp. noy.
Plate 10, figure 112; text figure DD, 21

DraGnosis.—This is a stout medium sized species with subrhomboidal body,
its length 1.45 transdiameters; girdle a descending left spiral, displaced 0.73
transdiameter ; sulcus extending from apex to antapex; surface coarsely striate ;
color, greenish yellow with coral-red pigment. Length, 934. Pacific off La
Jolla, California, August.

DescripTion.—The body is asymmetrical, subrhomboidal in shape, tapering conical anteriorly,
its length 1.45 transdiameters at the widest part, which is at the girdle. In cross-section the
body is nearly circular. The epicone and hypocone are subequal in size. In the mdividual
figured the posterior end was truncate and drawn out to the left, as though having recently
discharged a food body. A second individual showed the posterior end having a shape somewhat
similar to the anterior end. The epicone is broadly conical, subtending an angle of about 80°
with the right side almost twice the length of the left, and the apex narrowly rounded. The
length of the epicone on the left of the sulcus is 0.21 and on the right is 0.72 of the total length
of the body. The hypocone is distorted in the individual figured in that the antapex is drawn
out on the left side to a broadly truncate form. A second individual in the same material
showed the hypocone slightly rounder than the epicone with a broadly rounded antapex. Both
epicone and hypocone form wide, flaring shelves at the girdle region.

The proximal and distal ends of the girdle join the sulcus at about 0.21 and 0.72 respectively
of the total length of the body from the apex. The girdle sweeps around the body in a descending
left spiral course which is displaced at the right side posteriorly 0.71 transdiameter. The furrow
has a width of about 0.05 transdiameter, and is deeply impressed with broad, flaring borders
raised above the surface of the body. The anterior flagellar pore is located at the proximal
junction of the girdle and sulcus and the posterior pore slightly below the distal junction.

The suleus is a wide, deep trough which extends from the apex to the antapex in an almost
straight line. It varies slightly in width throughout, narrow anteriorly and wider posteriorly,
with smooth rounded borders.

The nucleus is large, kidney-shaped and is located slightly below the equatorial plane. It is
differentiated into two parts, an outer alveolar layer and an inner region filled with large
chromatin granules without linear arrangement. The outer layer is about 0.1 of the minor axis
of the nucleus in thickness and is composed of ellipsoidal, pink vacuoles arranged with their
long axis perpendicular to the surface of the nucleus. The major and minor axes of the nucleus
are 0.6 and 0.3 transdiameter in length respectively.

A large, sacklike pusule opens into the anterior flagellar pore. The cytoplasm is very finely
granular, clear and transparent. A large pink vacuole in the antapical region and numerous
dark refractive bodies were present, the products, probably, of holozoic nutrition. The general
color of the cytoplasm is greenish yellow. The surface is striate with rather widely separated,
equidistant, blue-green striae. These are more numerous on the hypocone, the epicone containing
approximately one-half the number on the hypocone. The striae on the epicone are beset with
masses of coral-red pigment and number 15 across the ventral face. The pigment may take the
form of beads or long masses following the line of striae, or of irregular splashes. Several large
rounded masses of coral red were located near the apex. A few granules of coral red were
found on the hypocone.

340 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Divensions.—Length, 79-90+; transdiameter, 52-68; axes of nucleus, 84
and 48+. ;

OccURRENCE.—Two individuals were taken August 8, 1917, with a No. 25
net, 4 miles off La Jolla, California, in a haul from 80 meters to the surface
and in a surface temperature of 21°9 C.

Activit1es.—The movements of this organism were rather sluggish, showing
a slow clockwise rotation. It invariably came to rest with the ventral face on
the substrate.

CoMPARISONS.—The relative proportions and size of this species alone
separate it from G@. corallinum (fig. DD, 12). The type of nucleus is peculiar
and constant in all of the individuals of both species that were observed. A
similar structure is found in Gymnodinium rubrum (pl. 8, fig. 86). It is unlike
anything found elsewhere in the Gymnodinioidae.

One might be inclined to regard this species as an aberrant form of G.
corallinum were it not for the fact that several individuals referable’ to it, of
apparently normal status, have been encountered. In addition the relative
degree of displacement of the girdle, with reference to the transdiameter, sep-
arates it from that species, as does also the location of the posterior pore. The
marked differences in the shape of the nuclei in the two species may be due to
approaching mitosis in the individual of G. virgatum which we figure, and not
to a fundamental specific difference.

Gyrodinium viridescens sp. nov.
Plate 4, figure 48; text figure DD, 11

DiaGnosis.—A small species with broadly subfusiform body, concave pos-
teroventrally, dorsoventrally flattened, its length 1.95 transdiameters; girdle
displaced one transdiameter ; sulcus encircling an apical lobe and reaching the
antapex; surface striate; color, pale pea green; littoral habitat. Length, 45.
Sandy beach of the Pacific at La Jolla, California, July.

DescripTion.—The body is broadly subfusiform, asymmetrical, tapering anteriorly, obliquely
truncate posteriorly, its length 1.95 transdiameters. Its greatest transdiameter is near the middle
of the hypocone, slightly anterior to the middle of the body. The dorsoventral diameter is 0.66
of the transverse one. The epicone forms less than 0.3 of the total body, its altitude at the
proximal and distal ends of the girdle being respectively 0.138 and 0.61 of the total length of
the body. Owing to the rapid descent of the distal end of the girdle the right ventral lobe of
the epicone is projected posteriorly as a slender triangular process. The apex is a rounded cone
higher than a hemisphere and somewhat more rotund on the left face and bears a central lobe
or button about 0.2 transdiameter across, encircled by the anterior end of the sulcus. The
hypoeone forms more than 0.7 of the whole body, and is higher and more convex on the left than
on the right side. From the midventral level posteriorly the whole ventral face is flattened and
somewhat coneave centrally, to such an extent that the posterior margin lies dorsal to the major
axis. The antapex is obliquely truncate for a width of 0.5 transdiameter and slopes from the
left posteriorly to the right at an angle of 10° from the horizontal.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 341

The girdle starts far anterior, within 0.13 of the total length of the body from the anterior
end, ascends about 0.5 furrow’s width in its proximal quarter, then descends in an ever steeper
spiral across the back and down the ventral face to its junction with the sulcus at about 0.61 of
the total length of the body from the apex. The total displacement is one transdiameter at the
widest part of the body, or 0.5 the total length. The furrow is about 0.11 of a transdiameter in
width, nearly uniform to the distal end where it narrows slightly, and is not deeply impressed.
The transverse flagellum nearly encircles the body. The suleus runs the whole length of the
body, passing anteriorly upon the epicone and almost completely encircling a central terminal
field as a slightly elevated button. It is very narrow and shallow in this region. It forms a
flat sigmoid curve on the ventral face and flares below the posterior flagellar pore located below
the junction of the distal end of the girdle, in a wide excavation 0.5 transdiameter in width
across the antapex. There is no flap over the suleus and the right posterior margin is the longer,
a distinction generally attained by the left side in most asymmetrical dinoflagellates. The
posterior flagellum extends beyond the antapex for a distance of 0.7 the total length.

The surface is finely and uniformly striate with equidistant longitudinal lines of equal
numbers on epicone and hypocone. There are about 18 across the ventral face. The nucleus is
ellipsoidal, located slightly anterior to the middle with its major axis inclined a little to the
right. Its length is about 0.6 transdiameter. Numerous small greenish bodies of varying sizes
and subspheroidal shape of a high refractive index fill the cytoplasm. They appear to be reserve
food of a fatty nature. Near the posterior end is a small ellipsoidal body of yellow ochre color,
either a chromatophore or a small ingested food body. The general color is a suffused pale pea
green without localized chromatophores.

Drmenstons.—Total length, 40-46; transdiameter at widest part, 22»; dorso-
ventral diameter, 16; length of nucleus, 16.

OccuRRENCE.—Rare in the beach sands off La Jolla, California, in July,
1914.

CoMParisons.—This species differs from all other species thus far described
in the genus (including all species in the old genus Spirodinium Schutt) in
that it has the well defined loop of the suleus around an apical button, as in
some forms of Cochlodinium. The posteroventral excavation is also unusually
extensive. The fine striation on the surface is a common feature in many
species, though the uniformity on epicone and hypocone is not so generally
present. It is most like Gyrodinium herbaceum sp. noy. and G. pingue (Schutt)
(figs. DD, 6, 15) in general form, displacement of girdle, asymmetry and ten-
dency to truncate form of the antapex. It is, however, much smaller, 45 instead
of 70» in length, has the apical loop of the suleus which Schutt (1895) does not
figure, and has the girdle more anteriorly located as a whole. It also lacks the
rhabdosomes or rodlets which appear to characterize Schutt’s species. In its
dorsoventral flattening, green color, and small epicone it approaches the species
of Amphidinium with which it is associated in the beach sands. It is the only
known arenaciphilous member of the genus Gyrodinium.

CHAPTER XIV

GYMNODINIIDAE: COCHLODINIUM

COCHLODINIUM Schiitt
Text figures O, FF-HH

Gymnodinium, Schiitt (1895), in part, pl. 22, fig. 72; pl. 23, figs. 75, 76; pl. 24, fig. 77; pl.
26, fig. 93.

Cochlodinium Sehiitt (1896), pp. 5, 6, figs. 1, 7.

Cochlodinium, Paulsen (1908), in part, pp. 103-105, figs. 142-145 (fig. 144 = Gyrodinium
longum).

DIAGNOSIS

Gymnodiniidae with torsion of the body of at least 1.5 turns; girdle a
descending left spiral of 1.5 or more turns, widely displaced; suleus with or
without apical and antapical loops and a torsion of 0.5 or more turns. Nucleus
usually in center or posterior part of body, rarely anterior; perinuclear mem-
brane generally absent ; moniliform chromatin strands distinct. Pusules usually
present, opening anteriorly into the anterior flagellar pore, posteriorly into the
posterior pore, frequently united at their extremities into one canal opening into
both pores. No nematocysts; plasma varying from colorless to highly colored;
chromatophores rarely present; holozoic nutrition prevalent; melanin or other
pigment granules sometimes present. Surface may be smooth or, less fre-
quently, striate. Encystment in thin-walled membrane frequent. Rarely a
tendency to colonial formation. Length, 27-200. All marine, eupelagic and
from warm temperate seas. Thirty species known.

ORGANOLOGY

In the elongation of the girdle and sulcus and the torsion of the body
resulting therefrom the genus Cochlodinium shows the greatest development in
the Gymnodinioidae, or indeed in the Dinoflagellata. The length of the girdle
(fig. FF, gir.) is intimately correlated with the torsion and constriction of the
body in Cochlodinium, differing in this respect from the genus Pouchetia, where
the length, course, and torsion of the sulcus are the outstanding features of
its organization. The greater development of the apical and antapical loops
of the suleus so striking in Pouchetia is foreshadowed in Cochlodinium in
C. clarrissimum (fig. GG, 2), C. miniatum (fig. GG, 6), and C. atromaculatum
(fig. HH, 6).

[342]

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 343

In the simpler, more generalized species of Cochlodinium we find a type of
girdle only slightly removed from that of Gyrodinium, as in C. scintillans (fig.
GG, 11), where the girdle is 1.5 turns in length, with a torsion of 0.5 in the
sulcus. The greatest development of the girdle is found in C. augustum (fig.
HH, 15), and C. pulchellum (fig. HH, 16), the former with four turns, the
latter with nearly three turns around the body, with a corresponding develop-
ment of the sulcus. Intermediate stages between these two extremes are
common.

The torsion of the body, as shown
in the sulcus, is confined almost exclu-
sively to the intercingular region with, %¢--------
rarely, an apical or antapical loop added
thereto. The striking exceptions are

CTS) Parsee

C. clarissimum and C. atromaculatum, é : ---=-- tr. fl.
the former with an apical, the latter S#/@----- a Ss
with an antapical loop. In this respect ne
the genus differs from Pouchetia, where DME
the apical or antapical regions may &!r----- Te
show as much if not more torsion than "------ 4
the intercingular area. Wh Caen sulc.

With the lengthening of the girdle aN ee eee Pig.
and the resulting torsion of the body a hyp (EE eee A na) Canny ee eg an
profound change takes place in the ori- =
entation of the organism. Considering pay bee ean poseap:
the longitudinal plane passing through ¥)
the flagellar pores as the dorsoventral arian eimai Ts
plane of the body, the two pores both |
open on the ventral face, as in Amphi- Fig. FF. Cochlodinium atromaculatum sp. nov.

Saye Cray viations: . p., anterior flagellar pore; epi.,
dinium, Gymnodinium, and nearly all >>reviations: ani. p., anterior flagellar pore; epi.
: c epicone; gir., girdle; hyp., hypocone; long. fl., longi-

the species of Gyrodinium. With the — tudinal flagellum; n., nucleus; pig., pigment; post. p.,
lengthening of the girdle in some species Pe Riosee eee ee Hae
of Gyrodinium and in Cochlodinium

the posterior pore is pushed around the body and, while the median longitu-
dinal plane lies midway between them, the morphological median dorsoventral
plane undergoes torsion with the body. Thus in all the simpler species of
Cochlodinium the anterior pore opens on the right, the posterior pore on the
left face of the figure, as in C. vinctum (fig. HH, 3). The posterior pore may
thus be carried completely around the body and regain its position in the same
median plane with the anterior pore, as in C. radiatum (fig. GG, 12) with two
turns of the girdle and in C. augustum (fig. HH, 15) with four turns of the
girdle. This position, however, in which both pores come to lie together in the
median plane, is secondarily acquired, and the morphological dorsoventral
plane has undergone a torsion of two or four full turns respectively to accom-
plish the results.

344 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The constriction of the body is closely correlated with the length of the
girdle and sulcus. In forms with the shorter girdle, as 1.5 turns in C. cavatum
(fiz. HH, 10), the body is nearly always greatly constricted on the morpholog-
ically ventral face, with a resulting ventral excavation of the body, as in C.
cavatum and C. helix (fig. HH, 8), or with the ventral surface thrown into
rounded lobes, as in C. vinctum (fig. HH, 3) and C. conspiratum (fig. GG, 10),
with the dorsal side convex in both cases. The most aberrant form in this
respect is C. distortum (fig. HH, 9). With the lengthening of the girdle the
constrictions extend around the body, as in C. lebowrae (fig. HH, 7), the number
of lobes increasing with the turns of the girdle and sulcus until the maximum
in the genus is reached in C. augustum (fig. HH, 15).

The borders of the sulcus are not protuberant, vet they are apparently
capable of great distension, as the sulcal area evidently forms the region for
the ingestion of food. Comparatively huge food bodies are frequently noted
in the cytoplasm, as in C. rosaceum (pl. 8, fig. 85), and the ingestion of these
must place great strain on the sulcal region, particularly in forms like C.
augustum.

The nucleus is usually located near the posterocentral part of the body.
Its chromatin contents are always arranged in the beaded, moniliform threads
characteristic of the Dinoflagellata generally. Two species only, C. miniatum
(fig. GG, 6) and C. strangulatum Schiitt, present a perinuclear membrane of
the type oceasionally found in Gyrodinium.

The cytoplasmic organization in the genus Cochlodinium never reaches the
relatively high degree of differentiation sometimes found in Gymnodinium and
Gyrodinium. The nearest approach to ectoplasmic differentiation is seen in
C. clarissimum (pl. 5, fig. 60), with its superficial vacuolated layer. The
peripheral zone of short rodlets so prominent in Gyrodinium is rarely met
with in this genus, C. citron alone presenting it (fig. HH, 12).

The surface of the body in this genus is relatively free from striae, and,
unlike the genus Pouchetia, striae are here associated with primitive or more
generalized species with one exception, C. distortum (fig. HH, 9). Only three
other species have striae, C. volutum (fig. GG, 1), C. pirum (fig. GG, 3), and
C. mineatum (fig. GG, 6).

The color of the cytoplasm in the genus Cochlodinium is varied, often bril-
liant and changeable in tone. The color may be diffused throughout, as in C.
rosaceum (pl. 8, fig. 85), C. citron (pl. 7, fig. 79), and C. conspiratum (pl. 3,
fig. 29), or it may be massed in clumps or irregular bodies. In C. radiatwm
(pl. 6, fig. 67) the aster-purple pigment is found in irregular, leaflike masses
scattered through the periphery. The yellow ochre of C. atromaculatum (pl. 7,
fig. 71) is scattered through the peripheral zone while the melanin is aggregated
into ellipsoidal masses along the girdle.

In C. distortum (pl. 7, fig. 78) the ochraceous-orange color is distributed
along the surface striae in globules of varying sizes, recalling similar conditions

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 345

in Gyrodinium, as in G. maculatum (pl. 6, fig. 62). One species, Cochlodinium
geminatum (fig. HH, 1), contains yellow-ochre chromatophores.

Nearly all the colors of the spectrum are to be found within this genus,
with a preponderance of yellow and yellow ochre. At the red end of the spec-
trum are C. archimedes, C. constrictum, C. rosaceum (pl. 8, fig. 85), and C.
miniatum (pl. 10, fig. 107), with aster purple in C. radiatum (pl. 6, fig. 67). A
faint reddish tone is found in C@. scintillans (pl. 10, fig. 113) and C. augustum
(pl. 5, fig. 53). Three species are green in color, C. convolutum (pl. 10, fig. 115),
C. fauret (pl. 2, fig. 25), and C. clarissimum (pl. 5, fig. 60), the latter obscured
by pink peripheral vacuoles. Two species have a bluish tint, C. vinctum (pl. 2,
fig. 15) and C. pulchellum (pl. 2, fig. 21), and the remainder are yellow and
yellow ochre in color, varying in a few species to a yellow green.

All the species in the genus Cochlodinium are probably holozoic in nutrition,
with the possible exception of the one species containing chromatophores, C.
geminatum. In the other species, with few exceptions, the cytoplasm contains
evidences of holozoic nutrition in the form of food masses, refractive rodlets,
vacuoles and oil globules, the accumulated products of metabolism. There is
some slight evidence in C. vinctwm (fig. HH, 3) of selective feeding.

Cyst formation is common throughout the genus, the cyst consisting of a
thin-walled hyaline membrane. Occasionally double cysts are formed, one
within the other. In some species binary fission takes place within the eyst,
as in C. pulchellum (figs. HH, 14, 16). In other cases cyst formation is evi-
dently correlated with the ingestion of food balls and serves as a digestion cyst,
as in C. clarissimum (fig. GG, 2) and C. cavatum (fig. HH, 10).

DISTRIBUTION

The genus Cochlodinium as a whole is somewhat more restricted in its range
than either Gymnodinium or Gyrodinium. It has no fresh-water represent-
atives. All the species thus far described have come from warm temperate
waters, with none from the polar or tropical seas. Possible exceptions to this
may be found in the species described by Schtitt (1895), since he unfortunately
omitted to mention the localities from which his species were obtained. They
were presumably from the Bay of Naples or the warm Atlantic from the col-
lection of the Plankton Expedition, and make up half the number of the pre-
viously described species. His species are C. constrictum, C. geminatum, C.
pirum, C. schuetti: (= Gymnodinium helix, Schutt, 1895, in part), and C. stran-
gulatum. Two more species described by Pouchet (1883, 1887) complete the
record for the Atlantic. These are C. archimedes and C. helix. C. pirum has
also been recorded from the Mediterranean at Naples, Italy, by Entz, Jr. (1909).

The only Cochlodinium thus far recorded from the Baltic is C. pellicidum,
near Kiel, Germany, by Lohmann (1908). A single species has been figured
from Yokohama Harbor, Japan, C. catenatum, by Okamura (1916). Three
species have been recorded from Plymouth Sound, England, by Miss Lebour
(1917D).

346 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Fig. GG. Cochlodinium. 1. C. volutum sp. nov. 2. C@. clarissimum sp. noy. 3. C. pirum (Scehiitt) Lemm.
After Schiitt (1895, pl. 23, fig. 76,). 4. C. fauwrei sp. nov. 5. C. cereum sp. nov. 6. C. miniatum sp. nov. 7.
C. elongatum sp. nov. 8. C. strangulatum Schitt. After Schiitt (1895, pl. 22, fig. 72,). 9. C. turbineum sp. nov.
10. C. conspiratum sp. nov. 11. C. scintillans sp. nov. 12. C. radiatum sp. nov. 13. C. constrictum (Schutt)
Lemm. Modified after Schiitt (1895, pl. 26, fig. 93). 14. C. catenatum Okamura. 15. C. pellucidum Lohmann.
After Lohmann (1908, pl. 17, fig. 21). X 500.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 347

Fig. HH. Cochlodinium. Magnification 500, except where otherwise stated.
Lemm. After Schiitt (1895, pl. 23, fig. 75., lower figure). 2. C. schwetti sp. nov.
4. C. rosacewm sp. nov. 5. C. convolutum sp. nov. 6 C. atromaculatum sp. nov.
helix (Pouchet) Lemm. 9. C. distortum sp. nov. 10. C. cavatum sp. nov.
sp. nov. 13. C. pulchellum Lebour. 14. C. pulchellum Lebour. X 625. Early stage of division.

sp. nov. 16. C. pulchellum Lebour. Late stage of division. 17. C. archimedes (Pouchet) Lemm. After Pouchet
(1883, fig. M).

1. C. geminatum (Schiitt)
3. C. vinectum sp. nov.
7. C. lebourae sp. nov. 8. C.
11. C. virescens sp. nov. 12. C. citron

15. C. augustum

348 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

To the single record made by Okamura for the Pacific we add in this paper
from the plankton off San Diego and La Jolla, California, the following species
previously described: C. catenatum Okamura, C. helix (Pouchet), C. pulchel-
lum Lebour, C. pirum (Schiitt) ; and the following twenty-one new species: C.
atromaculatum, C. augustum, C. cavatum, C. cereum, C. citron, C. clarissimum,
C. conspiratum, C. convolutum, C. distortum, C. elongatum, C. faurei, C. lebou-
rae. C. miniatum, C. radiatum, C. rosaceum, C. schuetti, C. scintillans, C. tur-
bineum, C. vinctum, C. virescens, and C. volutum.

The most widely distributed species is C. pirum, recorded from the Mediter-
ranean. the Atlantic, and the Pacific.

HistToricaL Discussion

The genus Cochlodiniwm was established by Schiitt (1896) for the forms
previously described as Gymnodinium without ocellus in which the girdle had
a length of 1.5 turns or more. His type species was C. strangulatum (= Gym-
nodinium strangulatum Schiitt (1895). He did not follow this up by sifting
out these species from Gymnodinium, and that was later done by Lemmermann

(1899) as follows:

Gymnodinium archimedes Pouchet (1883) == Cochlodiniwm archimedes (Pouchet) Lemm.
Gymnodinium helix Pouchet (1887) =Cochlodinium helix (Pouchet) Lemm.
Gymnodinium constrictum Sehiitt (1895) = Cochlodinium constrictum (Schiitt) Lemm.
Gymnodinium pirum Schiitt (1895) = Cochlodinium pirwm (Schitt) Lemm.
Gymnodinium geminatum Schiitt (1895) = Cochlodinium geminatum (Schiitt) Lemm.

In 1908 Lohmann added to the list of species in Cochlodinium two species,
C. pellucidum and C. longum. The latter form has a girdle which seems to make
one turn only about the body, hence we regard it as a Gyrodinium, and have
tentatively placed it in that genus as G. longum.

Okamura (1916) added one species to the genus, C. catenatum, and Lebour
in 1917 deseribed C. pulchellum, bringing the total number of valid species in
the genus up to nine: C. archimedes (Pouchet) Lemm., C. catenatum Oka-
mura, C. constrictum (Schiitt) Lemm., C. geminatum (Schiitt) Lemm., C. helix
(Pouchet) Lemm., C. pellucidum Lohmann, C. pirum (Schiitt) Lemm., C. pul-
chellum Lebour, and C. strangulatum Schiitt. To these we add herewith twenty-
one new species from the plankton of the Pacific off La Jolla, California: C.
atromaculatum, C. augustum, C. cavatum, C. cereum, C. citron, C. clarissimum,
C. conspiratum, C. convolutum, C. distortum, C. elongatum, C. faurei, C. le-
bourae, C. miniatum, C. radiatum, C. rosaceum, C. scintillans, C. schuetti, C.
turbineum, C. vinctum, C. virescens, and C. volutum.

SUBGENERA OF COCHLODINIUM
Subgenus 1. Cochlodinium subgen. nov.

Body not excavated sinistroventrally, girdle of 1.5 to 2, rarely 2.5, turns.
Type species Cochlodinium strangulatum Schutt.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 349

This subgenus includes all the species which do not show special differen-
tiation in the form of the body or the extreme amount of torsion, the greatest
amount being that indicated by two (or at the most 2.5 turns) turns of the
girdle. It is consequently the largest subgenus in number of species. These
fall naturally into three groups according to the amount of torsion of the body.
The first group, which we term the C. miniatwm group, has a torsion of the
body as shown in the girdle of 1.5 turns. It includes C. miniatum sp. nov., C.
scintillans sp. nov., C. turbineum sp. nov., C. catenatum Okamura, C. volutum
sp. nov., and C. pirum (Schutt). This group as a whole lies near the border-
line separating this genus from Gyrodinium. It also contains the only species
with striate surface, a striking Gyrodinium characteristic.

The second group, the Cochlodinium strangulatum group, has a torsion of
about 1.7 turns of the girdle. It contains C. strangulatum Schiitt, C. constric-
tum (Schitt), C. pellucidum Lohmann, C. conspiratum sp. noy., and C. cerewm
sp. nov.

The third group, the C. citron group, has a torsion of the body as indicated
by about 2 turns of the girdle. It includes C. citron sp. noy., C. lebourae sp.
noy., C. faurei sp. nov., C. clarissimum sp. nov., C. archimedes (Pouchet), C.
virescens sp. nov., C. radiatum sp. noy., C. atromaculatum sp. noy., and prob-
ably C. elongatum sp. nov.

Subgenus 2. Glyphodinium subgen. noy.

Body asymmetrical, excavated sinistroventrally, arched dextrodorsally, more
or less deeply incised by the sulcus, girdle of 1.5 to 1.6 turns. Type species,
Cochlodinium cavatum sp. nov.

This subgenus includes a small group of species with asymmetrical, more
or less excavated and constricted body. It includes Cochlodinium geminatum
(Schiitt), C. schwetti sp. nov., C. rosaceum sp. nov., C. vinctum sp. nov., C. con-
volutum sp. nov., C. helix (Pouchet), C. cavatum sp. noy., and C. distortum
sp. nov. These species form an orthogenetic series of increasing curvature and
distortion, culminating in the huge, much distorted and highly colored C.
distortum.

Subgenus 3. Polydinium subgen. nov.

Body elongate, fusiform, its length more than 2 transdiameters, girdle a
descending left spiral of more than 38 turns, sulcus with more than 2 turns.
Type species Cochlodinium augustum sp. nov.

This subgenus includes only those species with the extreme amount of torsion
of the body, as indicated by three or more turns of the girdle. It includes in
consequence the most highly differentiated species, in this particular, in the
genus. As might be expected, the number of species therein is small. It con-
tains only two species, Cochlodinium augustum, the type, and C. pulchellwm
Lebour.

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Key T0 THE Spectes oF Cochlodinium

We (Girdle “wath 25 =22 5s Granny) oo eae a
1 Girdle with s—1 turns (sulbsenusie Oly, Ghimipim) eres mee ee eee
2. Two sides of body symmetrical, girdle with 1.5-2.5 turns (subgenus Cochlodinium) ___.
2. Two sides of body markedly asymmetrical, girdle with 3-4 turns (subgenus Glyphodi-
WUT ORT) esa ee ne ee ee ee TE

3.. Girdle withvabout) d.5:turns ......2:. eS ee
3: Girdle: wathvalbbourt Dit ttiaerisy ce 5222 es ace ae ac
3: (Girdleywath ‘about! 2=2.5 stirs ess asa aos ee ees
42, \‘Surface-notistrlabe ro. casos oe sea ee
A. Siar Pace: Strate sx canes a ec a a ne SE
5; (Colored dish=greya sbodky, (biconical geese eee ere scintillans sp. nov.
Fz o(GOlOr SECO EO 5H CULO Wiss sown os es cae ae aca eae ee
6. Body obovoidal, narrower posteriorly, greem ............-.-..-.-2:--s-:s-ssess0se0-0-- turbineum sp. nov.
6) (Bodyzellipsoidaloreemishiy ello wpe se ee eee catenatum Okamura
fe Mueneth! 200 25h waths coral=redi pia ent essere eee ee miniatum sp. nov.
= Wenetholess Gham 1/00 rs mo reddy rn 0 aa wees en ee
8: Epicone smaller, tham hypocome, oreer cece cece ce nce volutum sp. nov.
8. Epicone and hypocone subequal, yellow ochre ................2....2----2--------t------- pirum (Schiitt)
9. Large species, 198, perinuclear zone present .................--2-----2--2-00---++ strangulatum Schiitt
9)'Smaller species» less) than™100p.)no peramucl ear zon G2 esses ee ee
10. Cytoplasm colorless, body subellipsoidal, 3839p. —.......-2...-2--------------- pellucidum Lohmann
MOS Colorpres ent sesso eres PRE ee eat ES ee oe Soest ai ane
Liles GirdlersalientAbodiysmosercol ors 90 presse te ee oe ere constrictum (Schiitt)
11/4 ‘Girdle not ‘salnentss body: syell owe ssc sexes ae ee ene Nee
12) Wiengthie2) transdiameters, 14 Op. cee scree secs ete cee ee conspiratum sp. noy.
12 ene thea transdiam eters set Opuresees ceceee scanners cee nes ee ee cereum sp. noy.
1132 (Girdle swaith2:5\Gurns) 2ose Colores s ee se es archimedes (Pouchet) Lemm.
ASS Girdle swat hiless isthe) 0b urera Ss) por teased Free eae
145 Marge species, exceeding MOQ pes cx s cose oe es eS snc eee
14.\Smaillex species; ‘less than! 00 j3:ces8s se ee ee ee ee ees
15. Body fusiform, 184», ochraceous with melanin ........................-..... atromaculatum sp. noy.
15. Body club-shaped, larger anteriorly, 174, opaline green -............... elongatum sp. noy.
16. Color bluish with aster-purple splotches, body broadly ellipsoidal — radiatum sp. noy.
16, ‘Color ereen to; yellow 25-222 aoe sosctese ecco car ie or SR Sa eres een
17. Color yellow to yellowish green ee a a reed ee EE OL IG ra
Uy a 50) Ko a 21) RE Rn rr er
18. Color amber yellow, not deeply constricted, radial rhabdosomes .................. citron sp. nov.
18. Color yellowish green, deeply constricted by suleus and girdle -......... virescens sp. nov.
19. Length 1.66 transdiameters, antapex contracted, lumiere green -............. lebourae sp. nov.
20: Giength’ 1.36 transdiameters; gneemishyoreiys sean ae ee ee faurei sp. nov.
20. Length 1.50 transdiameters, glaucous greem —_. 2 clarissimum sp. nov.
21. With vermiculate yellow ochre chromatophores, body contracted posteriorly -.................

pa ep beanie BES 12S. aaa aka Se ee ee ee oeminatumme(Sebulis)

10

11

14
15
16

iT
18
19

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 351

22. Body striate, orange yellow, labile, deeply constricted

DUA, ISI SETEMEN SY a a a eS oe SE EC eI Oe oh 23
PRB NOSIS LOS a a rosaceum sp. noy.
Poem Tem ye lOve OTe CECT eee eee sees ee ie eset se ee 24
Zee i elOD EEO tea tape xan pn OUD CRA pce. ents a Ree yes ences, wae ee ee 25
2A ee ATLL CXS yaLUTTLe Ls Call ea GUN) Cheese ren eee seen nae oe ee ees SS ee 26
29. Ventral’surface arched, 66; oil! yellow 2--.--22. 2 cavatum sp. nov.
25. Not arched ventrally, 54», yellowish green helix (Pouchet) Lemm.
26. Displacement of girdle .82 transdiameter, green ...........-.-.-------------- convolutum sp. noy.
2 Oem DISplacementslesset hanes 2 gute SC1 aM 6 Le Teams nearer tea eee erent eee 27
27. Antapex very rotund, glaucous blue with yellow tinge — 0. vinctum sp. noy.
27. Antapex flattened, pale yellowish green —.........2......-..--..-c2---ceececeeseeceeeeeeeee schuetti sp. nov.

2 Sem Cr Le MWC Dre mB ULUTTIS 9-4) jeigeeeeeessroene ee een ee enue er ee ee oe ES pulchellum Lebour
PSL, CG itierollke, Spoaeelan, 2B ibey ays] LTE eee ee ee ee a augustum sp. nov.

Cochlodinium archimedes (Pouchet) Lemm.
Text figure HH, 17

Gymnodinium archimedes Pouchet (1883), pp. 51, 52, fig. M; (1885@), pp. 52, 53, pl. 4,
fig. 41; (18850), pp. 529, 530; (1887), pp. 94, 95.

G. archimedes, Biitschli (1885), pp. 922, 924, 964, 965, 986, pl. 51, fig. 9.

G. archimedes, Schiitt (1895), p. 36.

Cochlodinium archimedes, Lemmermann (1899), p. 360.

C. archimedes, Paulsen (1908), pp. 103, 104, fig. 142.

DraGnosis.—A medium sized species with asymmetrical, ellipsoidal body,
its length 2.05 transdiameters; girdle a descending left spiral of 2.5 turns, dis-
placed 1.45 transdiameters ; sulcus with torsion of at least 1.5 turns; color, rose.
Length, 764. Concarneau, France.

DescripTION.—The body is ellipsoidal, somewhat constricted by the furrows; asymmetrically
rounded anteriorly, obliquely truncate posteriorly, its length 2.05 transdiameters at the widest
part near the middle. The epicone and hypocone are subequal in length, but the hypocone is
slightly greater in size. The epicone is small and button-like anterior to the proximal part of
the girdle. It has a length from the proximal and distal ends of the girdle of 0.13 and 0.85
respectively of the total length of the body. Its distal portion is a broad band, tapering distally
and making 1.5 turns around the body. The distal portion of the hypocone is convex ventrally,
concave dorsally, and obliquely truncate posteriorly.

The girdle joins the proximal end of the sulcus about 0.1 of the total length of the body from
the apex. It sweeps around the body in a descending left spiral course forming an angle of
about 30° to 35° with the longitudinal axis of the body. It passes around the body with 2.5
turns and meets the distal end of the suleus about 0.15 of the total length of the body from the
antapex. It is relatively wide and deeply impressed. The positions of the flagellar pores were
not recorded by Pouchet.

The suleus follows the course of the girdle in its posterior descent of 1.5 turns around the
body. It is shallow with a width about half that of the girdle, and terminates at its junction
with the girdle posteriorly. The anterior invasion of the epicone is not figured, but the proba-
bility of such an extension occurring is suggested by the notch on the dorsal side of the apex,
which in other species is usually made by the anterior end of the sulcus. The indentation at
the posterior end of the body also suggests its extension in that direction.

352 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The nucleus is ellipsoidal and is situated in the anterior part of the body. Its chromatin
contents are arranged in strands following its longer axis. Its major and minor axes are about
0.57 and 0.45 transdiameter.

Near the center of the body is a sphere formed by short rodlets radially arranged. This
probably corresponds to the large spherical masses with radially arranged rodlets such as are
figured in Gymnodinium dogieli sp. nov. (pl. 3, fig. 34) and G. radiatum sp. nov. (text fig. Z, 9).
In the anterior part of the body is an irregular searlet-pigment mass, which may probably be
the remains of a food body. This has been described by Paulsen (1908) as a stigma. It may
be, however, only a colored food mass such as may be seen occasionally in other species of the
Gymnodinioidae, as Gymnodinium aureum (pl. 1, fig. 5), Gyrodinium melo (pl. 5, 50), and
many others.

OccuRRENCE.—Figured by Pouchet (1888, 1885a) from the Atlantic off
Concarneau, France, in July.

SynonyMy.—This was originally described by Pouchet (1883, 1885a) as a
species of Gymnodinium, and was transferred to Cochlodinium by Lemmer-
mann (1899). In the form which Pouchet described in 1883 the girdle makes
two turns around the body, both ends terminating on the same face, resulting
in an entirely different dorsoventral orientation of the body. In his later
figure (1885a) the girdle makes 2.5 turns with the ends terminating on opposite
faces of the body. This, if valid, would place them in different species, but
Pouchet states in his later paper that the figure given therewith is a more correct
representation than his earlier figure.

Comparisons.—Only two species in the genus, C. augustum (fig. HH, 15)
and (. pulchellum (fig. HH, 16), have a greater torsion of the body than (C.
archimedes, the first having a girdle of four turns, the second of three turns.
It is placed in the C. citron group of the subgenus Cochlodinium, leading to-
wards the subgenus Polydinium.

Cochlodinium atromaculatum sp. nov.
Plate 7, figure 71; text figures FF; HH, 6

Diacnosis.—A large species with elongate ellipsoidal body, its length 2.7
transdiameters; girdle a descending left spiral of 2 turns, displaced 1.5 trans-
diameters; sulcus with antapical loop, torsion of 1.7 turns; melanin present;
color, grey and ochraceous orange. Length, 184. Pacific off La Jolla, Cali-
fornia, July.

DescriptioN.—The body is elongate ellipsoidal or asymmetrical subfusiform, obliquely trun-
cate anteriorly, tapering posteriorly and circular in cross-section, its length 2.7 transdiameters
at the widest part at the middle. The epicone exceeds the hypocone in size. It is relatively long
anterior to the anterior pore with nearly straight sides and obliquely truncate apex. Its length
at the proximal and distal ends of the girdle is 0.28 and 0.82 respectively of the total length of
the body. Posterior to the proximal junction of the girdle and suleus it becomes contracted to
a slender band which makes one complete turn around the body, ending in a slender point at the
distal junction. The hypocone sweeps around the body in a broad band from three to six times
the width of the posterior part of the epicone, making one complete turn above the distal junction
of the girdle and suleus. Posteriorly it forms a cone of about 65° with rounded antapex.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 353

The girdle meets the suleus at a distance from the apex at its proximal and distal ends of
0.28 and 0.82 respectively of the total length of the body. It sweeps around the body at an
angle of about 30° with the transverse plane, forming a descending left spiral of two turns,
joining the sulcus at a distance from the antapex of 0.16 of the total length of the body with a
displacement of 1.5 transdiameters. The furrow has a width of about 0.08 transdiameter and
is deeply impressed, undercutting the anterior border and curving gradually to the posterior
one. The borders are smooth and rounded. The suleus invades the epicone for a short distance
anterior to its proximal junction with the suleus. It sweeps posteriorly in a descending left
spiral which forms an angle of about 50° with the transverse plane in the first part of its course,
gradually changing in the latter part of its course to about 30°. The furrow is about half the
width of the girdle for the first half of its length, becoming narrower distally and enlarging
again posterior to the distal junction with the girdle. It is deeply impressed with rounded
sides. Posterior to the distal junction it makes a loop of nearly 0.6 turn, terminating at the
right side of the antapex on the dorsal side of the body. The anterior flagellar pore is located
at the anterior junction of the girdle and sulcus, the posterior pore a short distance beyond the
distal junction on the same side of the body.

The nucleus is an ellipsoidal body posterocentrally located, its long axis slightly oblique to
the transverse plane of the body. Its major and minor axes are 0.64 and 0.35 transdiameter in
length respectively.

Pusules were not present in the individual figured. The cytoplasm is coarsely granular and
is nearly filled with large ellipsoidal and spheroidal bodies and vacuoles of a clear, pale grey
color. Near the equatorial region were some smaller green oil globules and scattered over the
surface were minute blue-green droplets and mingled with them short green rodlets. In addition
a large, rounded, ochraceous-orange food mass was located near the anterior pore. Its eyto-
plasmic inclusions are evidences of a holozoic mode of nutrition. The color has for its back-
ground a pearl grey which is almost clear at the apex and elsewhere is thickly beset with minute
ochraceous-orange granules, or dots. These last are numerous near the surface and at the
antapex. Along the margin of the girdle and suleus are large pigment masses varying in size
and black in color. From the middle region of the body a few rows, four to a semicircle, of
small rod-shaped melanin granules extend to the girdle at the left of the sulcus, and at the right
of it to nearly midway between the anterior pore and the apex. No striae or other surface
markings could be detected, though the linear arrangement of the small melanin granules suggests
a fundamental linear organization of the superficial cytoplasm.

Drvensions.—Length, 183-185; transdiameter, 72/; axes of nucleus, 45
and 23; length of longitudinal flagellum, 454. The figure given of this species
(pl. 7, fig. 71) is the only one in our plates which shows the longitudinal flagel-
lum in any species with its full length.

OccURRENCE.—Two individuals were taken on July 20, 1917, with a No. 25
silk net 6 miles off La Jolla, California, in a haul from 80 meters to the surface
and in a surface temperature of 20°5 C.

ComPparisons.—This is one of the largest species of the genus Cochlodinium,
being exceeded in size only by C. strangulatum (fig. GG, 8) with a length of 210.
It is the only species in the genus showing the presence of melanin and the
second species in all of the genera below Pouchetia, the other being Gyrodinium
spumantia (pl. 7, fig. 72).

C. atromaculatum belongs in the citron group of the subgenus Cochlodinium,
and differs from the remainder of the group mainly in the greater elongation
of the body and in the presence of an antapical loop, the latter feature fore-
shadowing the condition in the higher genus Pouchetia.

354 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Actiyit1es.—This is an active organism, moving in loose circles in an anti-
clockwise direction with rotation on its major axis in a clockwise directon,
reversing occasionally.

Cochlodinium augustum sp. nov.
Plate 5, figure 53; text figure HH, 15

Diracnosis.—A large species with fusiform body, its length 2.3 transdiam-
eters; girdle a descending left spiral of 4.1 turns, displaced 0.74 total length;
suleus with short apical loop, torsion 3.1 turns; color, greenish grey with a
tinge of salmon pink; holozoic. Length, 1084. Pacific off La Jolla, California,
August.

Description.—The body is symmetrically fusiform, elongated, deeply constricted by girdle
and furrow, its length 2.3 transdiameters at the equator. The epicone very slightly exceeds the
hypocone in size. Its length at the proximal and distal ends of the girdle is 0.14 and 0.88
respectively of the total length of the body. The apex is asymmetrically rounded, deflected to
the left and only slightly grooved on the ventral surface by the shallow ascending loop of the
suleus. The hypocone has a length of 0.86 and 0.12 respectively of the total length at the
proximal and distal ends of the girdle. The antapex is flattened hemispherical in form, fur-
rowed ventrally by the distal end of the suleus, but is without a suleal notch in the postmargin.

The girdle leaves the suleus 0.14 of the total length of the body from the apex. It sweeps
around the body in a descending left spiral of 4.1 turns before joining the suleus distally at a
point distant from the antapex 0.12 of the total length of the body. It forms a fairly uniform
spiral deflected 20° from the horizontal except at the two ends where it is flattened almost to
the horizontal. It lies in a deep depression throughout its course and has high overarching
borders. The lips are smooth, with a green line along its anterior side. Its width is 0.09 trans-
diameter. The anterior flagellar pore is located at the anterior junction and the posterior
flagellar pore at the posterior junction of the girdle and suleus. The transverse flagellum was
very short in the individual figured, traversing scarcely 0.5 turn of the girdle. The longitudinal
flagellum is about half the length of the body in length.

The suleus invades the hypocone a short distance, forming a shallow, slightly curved loop
terminating near the apex. Below the pore it follows the course of the girdle midway between
its turns, reaching the posterior junction of the two after 3.1 turns. It lies in a narrow deep
depression and is a slender trough 0.5 the width of the girdle. Beyond the pore it traverses
the hypocone vertically for a short distance as a deep trough terminating near the antapex
without suleal notch.

The nucleus is an ellipsoidal body centrally located, its major axis nearly coinciding with
the short axis of the body. Chromatin threads could not be found in its very transparent
substance. Its major and minor axes are 0.5 and 0.3 transdiameter respectively in length.

A large club-shaped pusule opens anteriorly into the anterior flagellar pore and a slightly
smaller one posteriorly into the posterior pore. The cytoplasm is granular. A few small blue-
green oil globules were present, one group in the antcrior part of the body and another group
below the midregion, all near the girdle. In addition there were three groups of pink vacuoles
in the peripheral plasm, two along the left margin and a third of four much larger, ellipsoidal
vacuoles near the antapex. One large, spheroidal, greenish food mass was located near the
nucleus. Near the apex is a group of slender, sharp-pointed, greenish rhabdosomes or rodlets
arranged longitudinally near the proximal end of the girdle at the left of the main axis. The
color is a mixture of grey, blue green, and salmon pink, the last strongest around the border of
the body. No surface markings or striations were observed.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 39)

DimeEnstons.—Length, 1084; transdiameter at the widest part of the body,
47»; axes of nucleus, 25» and 16z.

OccURRENCE.—T wo individuals were taken August 13, 1917, with a No. 25
silk net in a haul 0.75 mile off La Jolla, California, from 83 meters to the
surface, in a surface temperature of 21°9 C.

Comparisons.—There are only four species of this genus larger than C.
augustum, to wit: C. atromaculatum, 184+; C. distortum, 156; C. miniatum,
200r; and C. strangulatum, 200#, This species has more torsion than any known
member of the Gymnodinioidae, or of the Dinoflagellata as a whole. The
nearest to it is in C. pulchellum Lebour (fig. HH, 16) with a torsion of its
sulcus of 2.25 turns to the 3.1 turns of C. augustum. It is the most specialized
member of the subgenus Polydiniwm and one of the most differentiated in
Cochlodinium also. Its specialization is also indicated by its large size. The
nine different channels which cross the ‘‘ventral’’ face of this organism are so
close to each other and divide up the surface so completely that there must be
considerable stretching and distension of adjacent regions wherever the animal
feeds on an object as large as the food ball figured in our specimen.

Cochlodinium catenatum Okamura
Plate 9, figure 105; text figure GG, 14
Cochlodinium catenatum Okamura (1916), p. 41, figs. 1-3.

Diacnosis.—A minute species with rotund ellipsoidal body, its length 1.29
transdiameters; girdle a descending left spiral of 1.5 turns, displaced 0.7 trans-
diameters; sulcus with torsion of 0.5 turn; color, light yellowish green to vellow
ochre; tending to form colonies. Length, 35. Pacific off La Jolla, California,
July, August; Yokohama Harbor, Japan, June.

Description.—The body is rotund ellipsoidal with broad, rounded apices, nearly circular in
cross-section, its length 1.29 transdiameters at the widest part, which is at the middle. The
epicone and hypocone are subequal in size. The epicone is subhemispherical anteriorly with
broad symmetrically rounded apex. It has a length from the proximal and distal ends of the
girdle of 0.25 and 0.80 respectively of the total length of the body. The hypocone is also sub-
hemispherical in shape with broad antapex slightly notched by the distal end of the suleus.

The girdle is a descending left spiral of 1.5 turns, distant from the apex at its proximal and
distal ends about 0.25 and 0.8 respectively of the total length of the body, with a displacement
of 0.7 transdiameter. The furrow has a width of about 0.07 transdiameter and is deeply
impressed with smooth, rounded sides. The sulcus invades the epicone to near the apex as a
slender trough which fades out anteriorly. Posteriorly it is deflected to the left below the
proximal junction with the girdle, with a torsion of 0.5 turn in the intercingular area before
meeting the distal end of the sulcus, beyond which it takes a nearly straight course to the
antapex. The anterior flagellar pore opens at the proximal junction of the girdle and sulcus,
the posterior pore at the distal angle of the posterior junction.

The nucleus is spheroidal and is located near the center of the body. Its axis is about 0.5
transdiameter in length.

The cytoplasm is finely granular, clear and transparent, and contained no vacuoles or other
cell inclusions in the individuals examined, while another contained a small, partly digested

396 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Gymnodinium, and a few slender, blue green rodlets. Nutrition is holozoic. The color is a
diffuse ight yellowish green. No striae or other markings could be detected on its surface. In
figure 105, plate 9, a chain of four zooids is figured. These are the products of recent mitoses,
which have not yet separated.

DimMeENsions.—Length, 35; transdiameter, 28-35; axis of nucleus, 14-16».

OccuRRENCE.—This was first seen July 12, 1917, when a single individual
and a chain of four zooids were taken with a No. 25 net in a haul 6 miles off
La Jolla, California, from 80 meters to the surface and in a surface temper-
ature of 20°6 C. On July 18 it was again present in a haul 4 miles offshore, in
a haul from 80 meters to the surface and a surface temperature of 20°8 C.

Okamura (1916) described this species from the waters of Yokohama
Harbor, Japan, in June, 1910 and 1911, at which time it occurred so abundantly
that the waters were discolored a dark reddish brown and fish were found float-
ing on the surface in a dying condition.

SynonyMy.—Okamura has described minute linear or dotlike chromato-
phores, yellowish brown in color, in the forms he observed. These were not
present in the individuals found at La Jolla and may possibly have been food
bodies or oil droplets. The two forms correspond so closely in other respects
that it seems inadvisable to separate them.

Comparisons.—Chain formation as a result of rapid schizogony is not un-
common in the Dinoflagellata; it may be temporary or permanent, and may
occur in both the naked and thecate forms. Many species of Gonyaulax and
Ceratium form temporary chains. One species of Gonyaulax (Kofoid and
Rigden, 1912) and the two species of the genus Polykrikos form permanent
colonies. In Okamura’s material single individuals of Cochlodinium catenatum
were rare, chains of 4, 8, 16, and intermediate numbers being common, showing
a strong tendency towards permanency or true colony formation.

This species belongs to the C. miniatum group of the subgenus Cochlodinium.
It is the smallest symmetrically ellipsoidal species in the genus, with the mini-
mum amount of torsion, and represents the most primitive condition in Cochlo-
dinium in structure.

Cochlodinium cavatum sp. nov.
Plate 9, figure 93; text figure HH, 10

Dracnosts.—A medium sized species with body asymmetrically reniform,
excavated ventrally, arched dorsally, with a right antapical lobe; length 2.25
transdiameters; girdle a descending left spiral of 1.5 turns, displaced 0.64 total
length; sulcus with apical and antapical loops, and a torsion of 0.5 turns, plasma
oil yellow. Length, 664. Pacific off La Jolla, California, July.

DescripTtion.—The body is elongated, markedly concave on the ventral face and convex on

the dorsal, thus throwing both apices excentrically ventrad. This gives to the body a twisted
reniform shape. The epicone exceeds the hypocone in length by 0.14 of the total length of the

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 357

body. The epicone has a length on the left of 0.23 and on the right of the sulcus of 0.87 of the
total length of the body. It is in lateral view a conoid of 35° with hemispherical apex. The
greatest length of the hypocone is 0.77 of the total length of the body, while at the right of the
suleus its length is only 0.13 of the total length. The antapical region is markedly asymmetrical,
the right side projecting as a hemispherical lobe 0.5 transdiameter in diameter.

The girdle joins the proximal end of the suleus 0.23 of the total length of the body from the
apex. It sweeps around the body in a descending left spiral course. In the proximal 0.5 turn
it is deflected posteriorly only about 15°, but in the next 0.5 it turns posteriorly in a sigmoid
curve deflected 45° to 60°, until it reaches a point 0.03 of the total length of the body from the
antapex, where it slackens again to 25° for a short distance and joins the distal end of the sulcus.
It is relatively wide, 0.14 transdiameter, and is deeply impressed with smooth overhanging
borders. The anterior flagellar pore opens at the anterior junction of the girdle and suleus, the
posterior pore, 0.5 transdiameter above their distal junction.

The suleus invades the epicone as a longitudinal groove which terminates near the apex. As
a descending left spiral it makes 0.5 turn before meeting the distal end of the girdle 0.13 of the
total length of the body from the antapex, where it forms a deep, wide excavation on the face
of the hypocone. It is a narrow, rather shallow groove with smooth borders lying in the ventral
spiral depression. Its total intercingular displacement is 0.64 of the total length of the body.

The nucleus is ellipsoidal and located slightly above the center of the body. Chromatin
threads could not be detected in its contents. Its major and minor axes are 0.69 and 0.36
transdiameter in length respectively.

A long sacklike pusule opens distally into each flagellar pore. The cytoplasm is finely
granular. There are a few blue-green refractive spherical oil drops scattered through it, and a
large food mass in the center. There were no striations or other markings on the surface. The
color of the organism is oil yellow shading to yellow ochre at the apices, with pearl grey massed
in the center. A thin-walled, symmetrically elliptical, hyaline cyst enclosed the organism. This
was surrounded by a second eyst, slightly larger than the inner one, of the same general appear-
ance and structure. There were no chromatophores and nutrition is evidently holozoie.

Drmenstons.—Length, 65; transdiameter, 27; axes of nucleus, 23 and 12+;
axes of outer cyst, 80# and 57“; of inner, 70 and 45.

OccuRRENCE.—A single individual was taken July 24, 1917, with a No. 25
net, in a haul 2.75 miles off La Jolla, California, from 80 meters to the surface
in a surface temperature of 21°9 C,

Activities.—These were limited to rotation within the cyst.

Comparisons.—This species is a member of the C. distortum group and is
next to C. distortum (fig. HH, 9) in the degree of ventral excavation and torsion
of the body. It has, however, more of the usual Cochlodinium proportions.
The asymmetry of the antapex allies it with the C. helix (fig. HH, 8).

Cochlodinium cereum sp. nov.
Text figure GG, 5

DiacNnosis.—A medium sized species with elongated, ellipsoidal body, its
length 2 transdiameters; girdle a descending left spiral of 1.7 turns, displaced

0.94 transdiameter; sulcus with apical and antapical loops and a torsion of one
turn; color, yellow. Length, 76. Pacific off La Jolla, California, July.

358 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

DescripTion.—The body is ellipsoidal, quite elongated, rounded anteriorly, truncate poster-
lorly, its length 2 transdiameters at the widest part at the middle. The left side is more
constricted by the furrows than the right. The epicone exceeds the hypocone in size, its length
being greater by about 0.1 of its own length. The epicone is elongate hemispherical, with a
length from the proximal and distal ends of the girdle of 0.27 and 0.76 respectively of the total
length of the body. The hypocone is less regular in outline than the epicone with a truneate
antapex shghtly notched by the distal end of the suleus.

The girdle is a descending left spiral of 1.7 turns and a displacement of 0.94 transdiameter.
The proximal transdiameter of its course is nearly transverse, changing to a posterior direction
with an angle of 20° to 35° from the transverse plane, flattening again somewhat distally. The
furrow has a width of about 0.07 transdiameter and is deeply impressed with smooth borders.

The suleus invades the epicone in a short loop which fades out below the right side of the
apex. It turns posteriorly in a descending left spiral which makes one complete turn about the
body, terminating at the right side of the apex with a broad, shallow notch at the postmargin.
About 0.4 turn of its course takes place posterior to its distal junction with the girdle. The
furrow is shallow, but constricts the body rather deeply in the intercingular area. Its width is
about 0.5 that of the girdle, widening at the posterior junction to a slightly greater width than
that of the girdle, with a still greater deflection of its sides near the antapex. The anterior
flagellar pore is found at the anterior junction of the girdle and suleus.

The nucleus is a rather small, ellipsoidal body, located posterior to the midplane, near the
dorsal side of the body. Its major and minor axes are about 0.52 and 0.36 transdiameter
respectively.

The cytoplasm is clear and finely granular and almost entirely free from spherules, vacuoles,
and food bodies. The color of the organism is yellow diffused through the cytoplasm. One
individual was enclosed in a spheroidal cyst with clear hyaline walls, very much larger than the
body.

Dmtexstons.—Length, 76; transdiameter, 38; axes of nucleus, 20v and 14+;
diameter of cyst, 108+.

OccuRRENCE.—This was observed July 9, 1904, in a haul made with a No.
12 net, 7 miles off San Diego, California, from 185 meters to the surface.

Comparisons.—This species belongs in the C. strangulatum group of the
subgenus Cochlodinium. It is close to C. citron sp. nov. (fig. HH, 12) and has
less torsion, lacks radial rhabdosomes, and has a smaller apical region. It lies
in the line of differentiation leading to the subgenus Polydinium, with 3 to 4
turns of the girdle.

Cochlodinium citron sp. nov.
Plate 7, figure 79; text figure HH, 12

DraGnosis.—A small species with elongated subellipsoidal body, its length
1.71 transdiameters; girdle a descending left spiral of 2.1 turns, displaced 0.88
transdiameter, sulcus without apical loop, torsion of 1.1 turns; color, amber
yellow. Length, 484. Pacific off La Jolla, California, July, August.

DescripTioN.—The body is subellipsoidal, tending towards obovoidal, with broad apices,
shghtly truncate posteriorly, nearly circular in cross-section, its length 1.71 transdiameters at
the widest part at the level of the proximal end of the girdle. The epicone exceeds the hypocone
in size. It is elongate hemispherical in shape with symmetrically rounded apex, and a length
at the proximal and distal ends of the girdle of 0.35 and 0.85 respectively of the total length of

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 309

the body. Posterior to the anterior flagellar pore it diminishes rapidly to a narrow band about
0.2 transdiameter in width, which makes one turn around the body, diminishing distally to a
slender point. The anterior portion of the hypocone forms a band somewhat wider than the
corresponding part of the epicone, and makes one complete turn above the distal junction of the
girdle and suleus. Posteriorly it is broad and rounded and notched at the left side of the antapex
by the distal end of the suleus.

The girdle is a descending left spiral with a distance from the apex at its proximal and distal
ends of 0.35 and 0.85 respectively of the total length of the body. It makes 2.1 turns around
the body and is displaced about 0.88 transdiameter. The furrow has a width of about 0.08
transdiameter, narrower distally, and is deeply impressed, undercutting its anterior border and
curving gradually out to the posterior one. The sulcus scarcely extends anterior to its proximal
junction with the girdle, but continues posteriorly in a descending left spiral of slightly more
than one turn and terminates in a noteh at the left side of the antapex. It forms a shallow
trough with smooth sides, and the width is less than half that of the girdle. The anterior and
posterior pores open at the anterior and posterior junctions of the girdle and sulcus respectively.

The nucleus is a spheroidal body filled with moniliform chromatin strands and loeated in the
anterior part of the body, dorsad to the anterior pore. Its axis is 0.53 transdiameter in length.

Small club-shaped pusules open into each flagellar pore. In one specimen examined the
posterior pusule was seen filling up with a sudden inrush from the outside surrounding medium.

The cytoplasm is finely granular. In the peripheral zone are numerous, light oriental green
rodlets placed perpendicularly to the surface (fig. HH, 12). These are about 7p in length and
arranged quite close together. Inside this zone and longitudinally arranged are about six long
slender curved rhabdosomes which persisted when cytolysis had caused the dissolution of the
body. Outside of these two regions and in the periphery are numerous blue-green rodlets with
larger patches of the same color, quite closely scattered through the peripheral plasm.

The color is an amber yellow shading down to an orange tint at the antapex. A few large
patches of yellow color are found near the apex and equatorial region.

Dimensions.—Length, 35-494; transdiameter, 25-324; axis of nucleus,
13-15e.

OccURRENCE.—This was one of the species most frequently taken, occurring
in most of the hauls made between July 12 and August 21, 1917, from distances
11, 6, and 4 miles off La Jolla, California, in hauls from 80 meters to the surface
and was also found in the surface hauls taken at the end of the pier at the
Biological Station. The forms figured came from the hauls made at the last
named point.

CoMPARISONS.—This species belongs to the C. citron group of the subgenus
Cochlodinium, characterized by two complete turns of the girdle. It stands
closest to C. clarissimum (fig. GG, 2), without, however, having the apical loop
of the sulcus and the superficial vacuolate zone of the latter species. In its
peripheral zone of radial rodlets it recalls the condition in many of the species
of Gyrodinium.

Cochlodinium clarissimum s). noy.
Plate 5, figure 60; text figure GG, 2
DraGnosis.—A medium sized species with rotund ellipsoidal body, its length
1.51 transdiameters; girdle a descending left spiral of 2 turns, displaced 0.76
transdiameter; suleus with apical loop and torsion of 2 turns; color, pale
glaucous green. Length, 59-. Pacific off La Jolla, California, July.

360 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

DescriptioN.—The body is rotund ellipsoidal with broad, rounded apices, nearly circular in
cross-section, its length 1.51 transdiameters at the widest part at the middle. The epicone
exceeds the hypocone in size, its length being greater by 0.13 of its own length. It is subhemi-
spherical in shape with broad apex. It has a length from the proximal and distal ends of the
girdle of 0.27 and 0.77 respectively of the total length of the body, the distal portion consisting
of a narrow band making one complete turn around the body. The hypocone is slightly broader
than the epicone, somewhat asymmetrical with broad antapex scarcely notched by the distal end
of the sulcus.

The proximal and distal ends of the girdle lie at a distance from the apex of 0.27 and 0.77
respectively of the total length of the body, having a displacement of 0.76 transdiameter. It
sweeps around the body in a descending left spiral course of two complete turns. The furrow
has a width of about 0.08 transdiameter, and is rather deeply impressed, the excavation under-
cutting the anterior border and curving gradually out to the posterior one. The anterior
flagellar pore opens at the anterior border of the junction of girdle and sulcus, the posterior
pore at the posterior border of the distal junction, on the same surface of the body.

The suleus makes one complete turn above the anterior flagellar pore, passing around the
apex and terminating just below it on the ventral surface near the right side. Below the pore
it passes directly backward a short distance before turning to the left and continues its course
as a descending spiral, making a complete turn before meeting the girdle, beyond which it
descends directly to the antapex. It thus makes two complete turns about the body. It forms
a narrow trough throughout its course anterior to the posterior flagellar pore, posterior to which
it widens to 3.5 times its own width and at the antapex makes a wider flare. The borders are
smooth and rounded.

The nucleus is subspheroidal in shape and located in the left side of the equatorial region.
Its axis is 0.5 transdiameter in length. Moniliform chromatin strands follow its longitudinal
axis In curving lines.

Small club-shaped pusules open into the anterior and posterior flagellar pores. The cytoplasm
is clear and finely granular. Beneath the peripheral layer-is a zone of vacuolate structure. The
vacuoles appear rounded in optical section (fig. GG, 2) and in surface view (pl. 5, fig. 60) as
irregularly shaped vacuoles closely pressed together over the entire surface. These seemed to
be filled with a pale rhodonite, pink-colored fiuid, the intervening spaces being greenish. Out-
side of this zone is a distinct periplast, appearing as a double-contoured wall. In the central
part of the body is a large ellipsoidal, greyish food mass and scattered through the cytoplasm
a few small oil globules. The color of the protoplasm is a pale glaucous green distributed
throughout. A thin-walled, hyaline cyst enclosed the individual figured.

Dimensions.—Length, 70-74"; transdiameter, 45-50; transdiameter of
nucleus, 16-18.

OcCURRENCE.—T wo individuals were taken on July 5, 1917, with a No. 12
silk net, ina haul 6 miles off La Jolla, California, from 80 meters to the surface
and in a surface temperature of 21°4 C. Several individuals were taken the
following week from approximately the same place and under the same condi-
tions. It was met again July 11 ina haul 4 miles off La Jolla with a No. 25 silk
net from 80 meters to the surface.

CoMParisons.—Cochlodinium clarissimum belongs to the citron group of the
subgenus Cochlodinium, and like C. citron (fig. HH, 12) and C. faurei (fig.
GG, 4) its girdle forms two complete turns around the body. The apical loop
is not found so fully developed elsewhere in this genus and resembles that
structure as developed in Pouchetia, as, for example, in P. subnigra.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 361

It is also peculiar in the genus Cochlodinium in the degree of its ectoplasmic
differentiation. This differs from the peripheral organization of the cytoplasm
in Gymnodinium, as developed in G. dogieli (fig. AA, 8), in which the vacuolate
layer is superficial, with the convexities of the individual alveoli roughening
the surface of the body. In Cochlodinium clarissimum the alveoli are more
deeply imbedded, the pellicle presenting a smooth surface.

Cochlodinium conspiratum sp. noy.
Plate 3, figure 29; text figure GG, 10

_Dtaenosts.—Small species, body broadly ellipsoidal to obovate, flattened and
incised on the left, arched on the right; length 1.2 transdiameters; girdle a
descending left spiral of 1.8 turns, displaced 0.7 transdiameter; suleus with
apical and antapical loops and torsion of 0.8 turn; plasma chalcedony vellow.
Length, 394. Pacific off La Jolla, California, July.

Descriprion.—The body is rotund, subellipsoidal to obovate, widest anteriorly, with its length
exceeding its transdiameter by only 0.2. Left face flattened, deeply incised at three points by
girdle and sulcus, right side more rotund. The epicone exceeds the hypocone in length by 0.2
total length. The epicone is broadly rounded at the apex as a somewhat flattened hemisphere.
It has a length at the proximal and distal ends of the girdle of 0.25 and 0.88 respectively of the
total length of the body. The hypocone is somewhat narrower than the epicone with a broad,
almost flattened but much contracted antapex. Its length at the proximal and distal ends of the
girdle is 0.75 and 0.12 respectively of the total length of the body.

The girdle forms a descending left spiral of 1.8 turns. It joins the suleus anteriorly 0.25
of the total length of the body from the apex. Its first 0.75 turn is almost horizontal or some-
what deflected anteriorly. It then turns abruptly posteriorly 45° from the horizontal for 0.5
turn, then flattens again almost to the horizontal for the last 0.6 turn around the body to meet
the suleus distally at the right of the antapex. Except in the middle part of its course on the
right dorsal side, it hes in a narrow, deep depression or trough with rounded borders. The
width of the furrow is 0.07 transdiameter. The anterior flagellar pore is located at the anterior
junction and the posterior flagellum slightly below the distal junction, on opposite faces of the
body. The transverse flagellum traverses only one turn of the girdle and the posterior flagellum
is 0.75 of the length of the body in length.

The suleus invades the epicone in a curving line to the left of the apex. Below the anterior
pore it takes a descending left spiral course of one complete turn, ending near the antapex.
After joing the girdle near the antapex its antapical loop makes 0.25 of a turn around the
antapex in a horizontal plane.

The nucleus is broadly ellipsoidal and is located in the posterior half of the body. Its major
and minor axes are 0.5 and 0.4 transdiameter in length respectively. Coarsely beaded chromatin
threads, eight across one face, traverse its shorter axis.

A small, sacklike pusule opens anteriorly into the anterior flagellar pore. The cytoplasm is
very clear and transparent, though filled with numerous inclusions. Six large, subspherical
food masses filled the center of the body. These varied in color from blue to grey green. Mingled
with these were a few minute oil droplets and refractive granules. The color is a pale chaleedony
yellow with a tinge of yellow ochre near the girdle. The proximal border of the girdle was
marked by a bright yellow-green line from which the color diffused into the adjacent eytoplasm.

362 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Divensions.—Length, 39; transdiameter, 31; axes of nucleus, 15v and 12+.

OccURRENCE.—This was taken July 26, 1917, with a No. 25 silk net, 2.5 miles
off La Jolla, California, in a haul from 80 meters to the surface, in a surface
temperature of 21°6 C.

CoMPaRISONS.—This species lies midway between C. vinctum (fig. HH, 3)
and C. geminatum (fig. HH, 1) in the degree of asymmetry and flattening. It
has more torsion than C. vinctum by nearly 0.5 turn, is only half the size and
has a horizontal extension of a longitudinal antapical loop of the sulcus. It
is also smaller than C. geminatum, lacks its distinct ochraceous chromatophores,
and has somewhat more torsion of the sulcus.

This species belongs to the C. strangulatum group of the subgenus Cochlo-
dinium, resembling other members of that group in the amount of torsion of
the body, as indicated by the number of turns of the girdle, but differing from
them in the type of spiral formed by the girdle. About 0.5 of the entire length
of the girdle encircles the anterior end, giving to the epicone a relatively small
proportion of the anterior surface of the body.

Cochlodinium constrictum (Schiitt) Lemm.
Text figure GG, 13

Gymnodinium constrictum Sehiitt (1895), pl. 26, fig. 93,.
Cochlodinium constrictum, Lemmermann (1899), p. 360.

DracNnosis.—A medium sized species with irregularly biconical body, its
length 1.38 transdiameters; girdle salient, a descending left spiral of about
0.18 turns, displaced about 0.76 transdiameter; sulcus extending from apex to
antapex, with torsion of about 1 turn; color, rose pink. Length, 90e. Atlantic
(?) or Bay of Naples.

DescripTION.—This description of this species is based on a single figure of Schiitt (1895,
pl. 26, fig. 93,), the data of which are inadequate on some points, such as the anterior termination
of the suleus and girdle and the distal end of the girdle. From a comparison of his figure and
other species of Cochlodinium one may approximately locate the position of the points mentioned.
This has been done in the following description.

The body is roughly biconical with rounded apices, salient girdle and constricted sulcus, length
1.38 transdiameters at the widest part, which is submedian. The hypocone exceeds the epicone in
size. The epicone has a length probably of about 0.17 above the proximal border of the girdle and
from its distal extremity of about 0.7 of the total length of the body. Its sides are unequally
rounded with a depression on the dorsal face, which may be the anterior end of the sulcus on the
ventral side, incorrectly drawn as on the dorsal surface. The apex is broadly rounded and blunt.
The hypocone diminishes to about half its width a short distance below the girdle, beyond which
it is rounded with a broad, blunt antapex.

The junction of the girdle and suleus occurs a short distance below the apex. It follows a
descending left spiral course around the body and meets the distal end of the sulcus about 0.3
of the total length of the body from the antapex. The girdle occupies a high, ridgelike portion
of the body, from which the surface slopes away on either side. The girdle itself is apparently
shallow with smooth borders.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 363

The sulcus occupies the trough between the two high ridges formed by the spiral course of
the girdle. It follows a descending spiral course which makes about one turn of the body. The
last part of its course is longitudinally directed, terminating at the antapex. The flagellar pores
are not figured.

The nucleus is spheroidal and is posterocentrally located. Its axis is about 0.3 transdiameter
in length.

The cytoplasm is apparently granular with a few small spherules anterior to the nucleus and
is diffusely colored rose pink.

Divenstons.—Length, 90; transdiameter, 654; diameter of nucleus, 21/.

OccurRENCE.—Figured by Schitt (1895) from the material of the Plankton
Expedition, presumably from the Bay of Naples or the Atlantic.

Comparisons.—C. constrictum is one of the few red or rose colored species
of the genus, sharing this feature with C. archimedes (Pouchet) Lemm., (C.
rosaceum sp. nov., and C. radiatum. It is unlike any other species in the salient
ridge in which the girdle lies, this usually being a region of constriction.

Cochlodinium convolutum sp. nov.
Plate 10, figure 115; text figure HH, 5

DraGnosis.—A rather small species with subovoidal body, contracted anter-
iorly, its length 1.44 transdiameters; girdle a descending left spiral of 1.6 turns,
displaced 0.82 transdiameter ; sulcus with apical and antapical loops and torsion
of 0.8 turn; color, green. Length, 49+. Pacifie off La Jolla, California, July,
August.

Description.—The body is subovoidal with broad apices, widest posteriorly, nearly circular
in cross-section, its length 1.44 transdiameters at the widest part. The anterior end is rounded,
the posterior end deeply excavated by the suleal notch. The epicone is exceeded in size by the
hypocone, its length being greater but its transdiameter less. It is convex-conical with a slight
concavity on the dextrodorsal side in the region of the anterior junction of the suleus and girdle.
It has a length from the proximal and distal ends of the girdle of 0.27 and 0.81 respectively of
the total length of the body. Its posterior portion is a slender pointed band which makes about
0.6 turn around the body. The hypocone is less symmetrical than the epicone, its ventral face
abutting on the girdle and sulcus, usually drawn out in a baglike extension which is separated
posteriorly from the dorsal surface by the suleal notch.

The girdle is a descending left spiral of 1.6 turns and a displacement of 0.82 transdiameter,
its proximal and distal ends having a distance from the apex of 0.27 and 0.81 respectively of
the total length of the body. The first 0.6 transdiameter of its course is nearly transverse,
turning posteriorly with an angle of about 30° with the transverse plane on the sinistrodorsal
surface, flattening to a nearly transverse plane in the dextrodorsal surface and again turning
posteriorly in the last part of its course on the ventral face. The furrow has a width of about
0.05 transdiameter and is usually deeply impressed with rounded, overhanging borders.

The suleus invades the epicone in a short wide loop which terminates below the apex on the
right side, or it may partly encircle the apex. Beyond the anterior flagellar pore it turns to the
left in a descending spiral course with a torsion of 0.8 turn. The furrow is narrow, less than
half the width of the girdle, widening slightly posteriorly where it deeply notches the antapex.
The anterior flagellar pore is located at the anterior junction of the girdle and suleus, the
posterior pore slightly beyond the posterior junction.

364 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The nucleus shown in the individual in figure 115, plate 10, has the elongated, curved form
of the predivision stage. It fills nearly the entire dorsoventral part of the body with a length
of about 0.7 of the total length of the body. Other individuals possessed ellipsoidal nuclei with
major and minor axes of about 0.6 and 0.5 transdiameter respectively.

Long club-shaped pusules open into either or both flagellar pores or they may be connected
at their extremities, forming a complete channel between the two openings. The cytoplasm is
clear and transparent and usually contains numerous blue-green spherules in the peripheral
zone. Food bodies, grey, yellow or yellow green in color are generally present in the cytoplasm,
indicating a holozoic type of nutrition. The general color is grey or greenish with a tinge of
yellow ochre near the apices. <A thin hyaline cyst often encloses the organism.

Dimenstons.—Length, 49-72"; transdiameter, 34-40; axes of nucleus, 164
and 134; length of cyst, 88.

OccURRENCE.—This was first observed in a surface haul made near the
Biological Station at La Jolla, California, July 27, 1914. It was again taken
in 1917. in hauls made July 20 and 23, 6 miles off La Jolla, from 80 meters to
the surface and in surface temperatures of 21° and 20°7 C respectively, and
on August 6, 4 miles offshore, from 60 meters to the surface and a surface
temperature of 21°1 C.

ComPparisons.—This species exhibits the same mobility of its posteroventral
surface as is found in C. cavatum (fig. T, 1), and in Pouchetia, as in P. macu-
lata (fig. T, 2), forming part of an orthogenetic line of evolution culminating
in Proterythropsis crassicaudata (fig. T, 3) and in Erythropsis (fig. T, 4),
where this region is prolonged into a well developed prod, or tentacle. It be-
longs in the subgenus Glyphodinium, near C. schuetti nom. sp. nov. (fig. HH, 2)
and C. helix (Pouchet) Lemm. (fig. HH, 8), differing from both in its greater
development of the apical loop of the sulcus and more deeply notched antapex.

Cochlodinium distortum sp. noy.
Plate 7, figure 78; text figure HH, 9

Dracnosis.—Very large species, with labile body deeply concave ventrally,
with subequal anterior, median and posterior lobes, apices broadly rounded ;
girdle a descending left spiral of nearly 1.5 turns, displaced at least 0.42 total
length of body; suleus with about 0.5 turn (morphological) ; nucleus anterior ;
surface striae beaded with orange. Length, 155#. Pacific off La Jolla, Cali-
fornia, July.

DescripTiIoN.—The body is profoundly distorted by constrictions which mark off three sub-
equal anterior, median, and posterior lobes and by a deep ventral concavity and dorsal arching
of the median lobe, so that the body has the form of a three-lobed kidney. The three lobes are
about equal in volume and in diameter, except that the median lobe is somewhat narrower and
longer than the others and deficient ventrally ; the posterior lobe is perhaps a trifle the largest.
The body is also twisted in the direction of the usual torsion of the sulcus, thus adding to the
difficulty of interpretation. Its length is 2.25 transdiameters measured across the terminal lobes
which are equal in this dimension.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 365

The epicone exceeds the hypocone by 0.08 total length and contains parts of all three
lobes. Its length at the proximal and distal ends of the girdle is 0.33 and 0.75 respectively of
the total length of the body. The apex is hemispherical. The hypocone has a length of 0.67
and 0.25 total length respectively at the two ends of the girdle and a subhemispherical antapex,
somewhat deflected ventrally and slightly flattened on the ventral face posteriorly. The deep
concavity affects the intercingular region of these two segments of the body.

The girdle pursues a somewhat erratic course owing to the concavity and torsion of the body.
It forms a descending left spiral with a total displacement of 0.45 total length. From its
junction with the anterior end of the sulcus it makes 0.5 turn in the horizontal plane, turns
posteriorly at the right face along the arched dorsal side of the middle lobe, and upon its contact
with the posterior lobe turns again to an almost horizontal, somewhat sinuous course for the
last 0.75 turn. Its total course is thus about 1.5 turns. The amount of the torsion and resulting
overlap may be greater than this, as is indicated by the course of the surface striae, but its
determination is obscured by the ventral concavity. The furrow is 0.06 transdiameter in width,
and is not deeply impressed.

The suleus does not extend anteriorly above the junction with the girdle and is hidden
posteriorly in the concavity. It makes about 0.5 turn of a descending left spiral, continues
posteriorly below its junction with the distal end of the girdle about half way to the antapex.
Its total length in the anterior-posterior direction is 0.56 total length or more, of which 0.42 is
intercingular. The anterior pore is at the anterior junction and the posterior one about one
width of the furrow below the posterior junction.

The nucleus is a homogeneous ellipsoidal body located almost transversely in the extreme
anterior end of the body. Its axes are 0.74 and 0.50 transdiameter in length respectively. A
small spherical pusule opens by a short canal anteriorly into the anterior flagellar pore, and
a smaller one also opens anteriorly, instead of posteriorly as usual, into the posterior pore. There
were no chromatophores, food balls, oil globules, or rhabdosomes. The cytoplasm was remarkably
clear and free from coarse vacuolation. The surface was striate with fine greenish yellow lines
running longitudinally parallel to the morphological axis from apex to antapex. Scattered
along their courses at somewhat regular intervals are numerous orange globules of varying size.
They ure somewhat more crowded near the girdle and the apices of the body.

Dimenstons.—Length, 155“; transdiameter of terminal lobes, 70“; axes of
nucleus, 50# and 37-.

OccCURRENCES.—One individual taken 4 miles off La Jolla, California, on
July 27, 1917, in a haul from 80 meters to the surface in a surface temperature
of 21°9 C.

Activitres.— Both flagella were normally active and the animal moved inter-
mittently with a jerking motion. There was no evidence of abnormality in its
activities. The body was exceptionally plastic and labile.

ComPsrIsON.—This is one of the most aberrant types of the genus Cochlo-
dinium, not far from Gyrodinium in the amount of torsion, and striate, as is
often the ease in species of that genus. The location and axial position of the
nucleus, together with the deep concavity and distortion of the body, suggests
the possibility that this was a form in the telophase of binary fission, but no
second nucleus was present in the translucent posterior end. The form also
suggests mechanical distortion, but there was no change prior to those which
lead to cytolysis and there were none of those evidences of mutilation or ab-
normality which are readily detected. The form is bizarre, but not clearly
abnormal, and its activities were of the normal type.

366 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The species also represents the extreme specialization of a line of species
in which the sinistroventral region is deeply incised or concaved by the sulcus
and the dextrodorsal one more or less arched. This series progressively includes
C. geminatum, C. schuetti (fig. HH, 2), C. vinctum (fig. HH, 3), C. rosaceum
(fig. HH, 4), C. convolutum (fig. HH, 5), C. helix (fig. HH, 8), and C. cavatum
(fig. HH, 10), and culminates in C. distortum (fig. HH, 9).

Cochlodinium elongatum sp. nov.
Plate 4, figure 45; text figures 0; GG, 7

DescripTion.—The body is long cigar-shaped, its length 3.78 transdiameters at the widest
part, which is anterior. It was enclosed in a cyst only very slightly wider than itself but with
a somewhat greater length. The cytoplasm is granular, clear and dull opaline green in color. A
few refractive rodlets were present near one end (anterior) and a single large vacuole near
the other.

When this organism was first observed a Cochlodinium-like girdle or furrow followed a spiral
course around the body from one end to the other (pl. 4, fig. 45), and the nucleus presented the
appearance of a late telophase stage of division, with the chromosomes plainly evident. Shortly
after it was first seen the furrow became obliterated and the body divided into two portions
(fig. O, 2). A second division of both nucleus and cytoplasm took place (fig. O, 3), followed in
a short time by a third division which resulted in the production of eight small bodies within
the cyst (fig. O, 4). Further development did not take place, though it was still held under
observation for a short time when it began to disintegrate.

A single specimen of this peculiar organism was observed in the plankton at La Jolla and
one that was not adequate for clearly determining its systematic position and relationships. Its
undoubted girdle, dinoflagellate type of nucleus and peculiar type of division place it with the
dinoflagellates and is deemed important enough to record its occurrence here, leaving further
investigation to determine its status more fully.

A comparison of our figures (fig. O) and those of Chatton (1906) for Blastodinium pruvoti
(fig. J) shows a striking similarity between the two forms. In Blastodinium, however, according
to Chatton, the body is spirally encircled not by a furrow or girdle but by a series of fine spines,
linearly arranged. This difference would effectively separate the two forms and this separation
is further widened by the ensuing development. In Blastodinium the body divides into two
portions, and these follow individual lines of development, the body increasing to nearly three
times its former size (figs. J, 2, 3, 4), the final result being the production of small Gymnodinium
(fig. J, 5). No evidence has been found of a similar division of the body into macrocyte and
microcyte in our form. It seems then that in spite of close resemblances in form and identity
in size these two organisms cannot be considered generically related.

Drenstons.—Length, 174; transdiameter, 464; length of cyst, 195z.

OccURRENCE.—This was taken August 10, 1917, in a haul one mile off La
Jolla, California, from 50 meters to the surface, and in a surface temperature
of 22°5 C.

Cochlodinium faurei sp. nov.

Plate 2, figure 25; text figure GG, 4
Dr1aGnosts.—A medium sized species with rotund, subovoidal to ellipsoidal
body, its length 1.36 transdiameters; girdle a descending left spiral of two
turns, displaced 0.78 transdiameter ; sulcus with apical and antapical loops and

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 367

torsion of 1.2 turns; color, greenish grey. Length, 564. Pacific off La Jolla,
California, July, August.

DescripTION.—The body is of robust habit, subovoidal to ellipsoidal in shape, moderately
constricted by the furrows, circular in cross-section, sightly broader anteriorly, its length 1.36
transdiameters at the widest part. The epicone and hypocone are subequal in size. The epicone
is rounded anteriorly or may have the appearance of a broad flat cone, with blunt apex. It has
a length at the proximal and distal ends of the girdle of 0.18 and 0.83 respectively of the total
length of the body. Its distal portion forms a narrow band anteriorly, becoming wider and
again contracting to a slender point distally. The anterior portion of the hypocone is wider
than the corresponding part of the epicone, with its sides rounded posteriorly and the antapex
deeply notched by the distal end of the sulcus.

The proximal and distal ends of the girdle lie at a distance from the apex of about 0.18 and
0.83 respectively of the total length of the body. It forms a descending left spiral of two
complete turns, the first and last parts of its course having a nearly transverse direction for
about 1 transdiameter, the remainder of its course forming an angle of 25° to 30° with the
transverse plane of the body. The furrow varies slightly in width, its average being about 0.04
and 0.06 transdiameter. It is deeply impressed, often constricting the body, with the excavation
undercutting both borders, either of which may be smooth or with an irregular wavy outline.

The sulcus extends anteriorly from the anterior flagellar pore to the left side of the apex in
a lightly curved line. After passing the proximal end of the girdle it turns towards the left
and sweeps around the body in a descending left spiral which makes slightly more than one turn
before meeting the distal end of the girdle, beyond which it follows a straight line to the antapex.
Its width is less than half that of the girdle except at the region of the anterior pore and the
distal end of the girdle. It expands near the posterior end of the body, deeply notching the
antapex. The anterior flagellar pore is found at the proximal end of the girdle, the posterior
pore just beyond the distal junction of the girdle and sulcus.

The nucleus is spheroidal to ellipsoidal in shape and is located in the posterior part of the
body. It is filled with moniliform chromatin strands. Its axes are about 0.46 and 0.4 trans-
diameters in length respectively.

The cytoplasm is finely granular, but usually very clear and transparent. Small sacklike
pusules may be present at either or at both pores. In one individual the posterior pusule was
rather short with two subequal diverticula starting from its proximal end. Food bodies are
generally present in the cytoplasm, the individual shown in figure 25, plate 2, having one large
yellowish mass centroanteriorly, with several green and dark refractive bodies near it. Small
blue-green oil droplets were present in the peripheral zone. The general color of the organism
is pearl grey and green, a few individuals showing a yellowish green tone. No striae or other
markings could be detected on its surface.

Druenstons.—Length, 55-60“; transdiameter, 3541+; axes of nucleus, 194
and 16r.

OccurRENCE.—A single individual was taken July 20, 1917, with a No. 25
net, 6 miles offshore at La Jolla, California, in a haul from 80 meters to the
surface and in a surface temperature of 20°5 C. It was also found July 24,
2.75 miles offshore, and August 17, 0.75 miles offshore, in hauls from 80 meters
to the surface and surface temperatures of 21°9 C and 22°5 C.

Comparisons.—This species belongs to the subgenus Cochlodinium, a group
showing considerable symmetry of form, and stands next to C. clarissimum
(fig. GG, 2) in size and proportion, but the uppermost part of the epicone is
much smaller, the apical loop of the sulcus less developed, its peripheral plasma
less differentiated, and its color slightly different.

368 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Cochlodinium geminatum (Schiitt) Schiitt
Text figure HH, 1

Gymnodinium geminatum Sehiitt (1895), p. 165, pl. 23, fig. 75.
Cochlodinium geminatum, Schiitt (1896), p. 2, fig. 1.
C. geminatum, Lemmermann (1899), p. 360.

DraGNnosts.—Small species, body subellipsoidal, its length 1.4-1.67 trans-
diameters; girdle a descending left spiral of 1.5-2 turns, displaced about 0.8
total length; sulcus with 0.5-1 turn; chromatophores vermiculate, ochraceous ;
cyst pyriform. Length, 47-754. Atlantic or Bay of Naples; Pacific off La
Jolla, California, July.

Description.—This is based wholly on Schiitt’s (1895, 1896) figures, as the species did not
oceur at La Jolla in 1917 and our earlier notes are uncritical on its morphology. Serious
difficulties are encountered in attempting to work out the morphological features from these
figures because all of them are based on individuals in chain subject to modifications at fission,
such as expansion of the conjoined ends, modification in the distinctness of and course of sulcus
and girdle, and possible complications of and changes in torsion. Furthermore, there are wide
differences between Schiitt’s three figures in size and proportions. These appear to be due to
the rounding-up prior to cytolysis, but the differences in size, such as exist between his figures
75, and 75, (75h and 47), when correlated with marked differences in torsion (about 0.5 and
1 turn of the suleus) are at least puzzling and raise the question as to the specifie identity of
the individuals shown in these two figures. The perplexities are increased when in a later paper
(1896) Schiitt reverses the orientation of the cyst of his earlier paper (pl. 23, fig. 75,) and
includes in it his figure 75,. On the comparison of Schiitt’s figure 75, with related species the
orientation he uses here (1895) appears to be justified, but it hardly seems probable that the
chain could turn end for end, as it must do, if his later orientation of the cyst (1896, fig. 1),
containing what appears to be the chain of his earlier (1895) figure, is correctly oriented. In
short his (1896) orientation of the cyst about the chain in the later figure is irreconcilable with
his earlier (1895) figures. A brief attempt to analyze the morphology of this species follows.

The body is subellipsoidal, wider near the middle, sometimes slightly flattened in the sinistral
face and bulging on the dextral; length, 1.40—-1.67 transdiameters. Epicone and hypocone sub-
equal. Apex asymmetrically subconical (90°), deflected to the right. Antapex also asymmet-
rically rounded, subconical to flattened; deflected to the right. The girdle is a descending left
spiral of about 1.5 turns (Schiitt, 1895, pl. 23, fig. 75,), or 2 turns (fig. 75,). Its anterior end
almost reaches the apex, whence it descends in a fairly uniform spiral to within 0.2 of the total
length of the antapex, having a total displacement of nearly 0.8 total length. The furrow is
wide, 0.12 transdiameter in width, deeply impressed with overhanging lips. The suleus is not
clearly shown, but appears to run from apex to antapex with a torsion of 0.5-1 turn of a
descending left spiral. It is about half the width of the furrow and does not constrict the body.
There is no apical loop above the anterior junction with the girdle and the extension beyond
the posterior junction is short or lacking.

The nucleus is central, spherical, or broadly ellipsoidal, 0.5-0.7 transdiameter in diameter
or major axis, and crowded with moniliform chromatin threads of uniform granules. The
ochraceous chromatophores he uniformly distributed and about equidistant in the peripheral
plasma. They are vermiculate rodlets about 0.2 transdiameter in length and with a diameter
0.2 their length. They straighten out and round up into spherules as cytolysis approaches. One
or more pusules lie near the anterior flagellar pore.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 369

This species is generally seen in chains of two or four individuals within a pyriform trans-
lucent gelatinous cyst whose length is about five times that of the body. Schiitt figures this with
the broader end posterior in his earlier paper (1895) and anterior in the later one (1896).
After treatment with safranin the cyst shows granular concentric laminations surrounding a
non-laminate axial region containing the chain.

Drvexstons.—Length, 47-75; transdiameter, 35-45; axes of nucleus, 22
and 302; length of cyst, 1854; diameter, 108.

OccurRRENCE.—Taken on two occasions in the plankton off La Jolla, Cali-
fornia, in 1906, once on July 3, 2.75 miles offshore in a haul of a No. 20 net
from 185 meters to the surface in a surface temperature of 20°4 C, and again
on July 10 in a surface haul of a No. 12 net, 2 miles offshore in a surface tem-
perature of about 20°9 C. In both instances chains of four individuals were
found. On July 10 the species was fairly abundant.

Schiitt (1895) figures it presumably from the Bay of Naples or from the
collections of the Plankton Expedition in the Atlantic. It has not been reported
elsewhere.

Actrivittes.—The individuals, both free and in chain, round up and cytolize
quickly. Individuals in chain frequently separate when stimulated by the
illumination of the microscope. When this occurs in a cyst the remnants will
fuse into a single sphere. As eytolvsis approaches the surface is wrinkled
locally by waves of contraction producing pseudopodia-like elevations. The
pellicle becomes detached locally after these contractions, a clear fluid oozes
out at the flagellar pores, along the furrows and elsewhere, and when the pellicle
about the now spheroidal mass ruptures the cytoplasm flows out and is speedily
dissolved.

Comparisons.—Too little is critically known of this species for comparisons.
It is not far from C. conspiratum (fig. GG, 10) on the one hand and C. cate-
natum (fig. GG, 14) on the other. The latter tends to form chains, but is
smaller, appears to have less torsion, 0.5 turn only, and less intercingular dis-
placement, 0.6 instead of 0.8 total length, and to be nearly colorless instead of
having ochraceous chromatophores. C. geminatum is more elongated and less
incised than C. conspiratum and has chromatophores, which the latter lacks.
Note should be made of the fact that the more elongate individuals with two
turns of the girdle which Schiitt (1895, pl. 23, fig. 75.) figures are very close to
C. archimedes (Pouchet) Lemm. (fig. HH, 17) in size, proportions, and torsion,
and should be classed with it were it not for the implication which Schitt’s
(1896) later figure raises, that it is a phase of the chain of his other figure
(fig. 75.) in whieh prior to fission the torsion has increased 0.5 turn and the
girdle and sulcus have elongated considerably. It is the least distorted member
of the C. distortum group of the subgenus Glyphodinium and might equally
well be placed in the C. citron group of the subgenus Cochlodinium.

SynonyMy.—This species was figured by Schiitt (1895) as Gymnodinium
geminatum, but noted later by him (1896) as a Cochlodinium.

370 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Cochlodinium helix (Pouchet) Lemm.
Plate 9, figure 92; text figure HH, 8

Gymnodinium helix Pouchet (1887), pp. 94-96, fig. 1.

G. helix, Schiitt (1895), pp. 59, 71, pl. 24, figs. 77,_, (fig. 77, is Cochlodiniwm schuetti
nom. sp. nov.).

Cochlodinium helix, Lemmermann (1899), p. 360.

Gymnodinium helix, Entz, Jr. (1907), p. 11; (1909), p. 246.

Cochlodinium helix, Paulsen (1908), p. 103, fig. 143.

C. helix, Lebour (19176), p. 103.

DraGnosis.—A small species with subovoidal asymmetrical body, its length
1.42 transdiameters; girdle a descending left spiral of 1.5 turns, displaced 0.65
transdiameter; sulcus with apical and antapical loops and a torsion 0.8 turn;
color, dull yellow green. Length, 54». Atlantic off Concarneau, France;
Plymouth Sound, England, August; Pacific off La Jolla, California, July,
August.

Drscription.—The body is irregularly subovoidal, broad and asymmetrical posteriorly, nearly
cireular in cross-section, its length 1.42 transdiameters at the widest part in the lower hypocone.
The anterior end is tapering, the posterior broad, the posteroventral face drawn out into a flap-
like extension on its morphological right side, giving to the body a sinistroventral excavation,
with the dorsal side strongly convex. The epicone and hypocone are subequal in size. The
epicone is convex-conical, about 45° anteriorly, with blunt apex. It has a length from the
proximal and distal ends of the girdle of about 0.21 and 0.84 respectively of the total length of
the body. The hypocone is broader than the epicone, less symmetrical, the dextroventral face
drawn out into an outstanding flap or lobe, still further marked off posteriorly by the deep
suleal notch.

The girdle is a descending left spiral of 1.5 turns, displaced about 0.65 transdiameter. The
anterior part of its course is nearly transverse, turning posteriorly on the left side at an angle
which flattens to a nearly transverse plane at the dorsal margin, crossing the right transversely
and turning posteriorly around the outstanding flap which is composed of portions of both
epicone and hypocone. The furrow has a width of less than 0.05 transdiameter and is lightly
impressed with rounded borders.

The suleus invades the epicone in a short loop which may partly encircle the apex or may
terminate below the right side. It passes posteriorly in a left spiral direction, its torsion about
0.8 turns. It deeply constricts the body in the intercingular area, lying at the base on the left
side of the outstanding flaplike portion of the body. It meets the distal end of the girdle at the
posterior point of emergence of the flap from the main body. The furrow is somewhat narrower
than the girdle. The anterior and posterior flagellar pores are found at the anterior and posterior
junctions of the girdle and sulcus respectively.

The nucleus is spherical to ellipsoidal in outline and is located in the posterior portion of the
body. It is filled with fine, moniliform chromatin strands. Its axis is about 0.4 transdiameter
in length.

The long, sacklike pusules opening into each flagellar pore are connected at their extremities,
forming a tubular canal between the two openings. The cytoplasm is finely granular. The
centroanterior portion of the body was oceupied by a pale dull yellow green food mass. Blue-
green spherules are usually abundant in the peripheral zone. The general color of the organism
is dull yellow green with a tinge of orange in the posterior part. A thin-walled, hyaline, nearly
circular eyst enclosed the organism.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 371

Dimensions.—Length, 45-544; transdiameter, 31-354; axes of nucleus,
15-20e and 12+; diameters of cyst, 50# and 53+.

OccuRRENCE.—Two individuals were taken July 27, 1917, 4 miles off La
Jolla, California, in a haul from 80 meters to the surface and in a surface
temperature of 21°9 C. It was also present August 15 in a haul 0.75 mile
offshore, from 70 meters to the surface.

Tt was described by Pouchet (1887) from the Atlantic off Concarneau,
France, where it was abundant from April 29 to May 3. It has also been
recorded from Plymouth Sound, England, by Lebour (1917b) in August.

SynonyMy.—Figured by Pouchet (1887) as Gymnodinium helix, the name
was changed by Lemmermann (1899) to Cochlodinium helix. Schiitt (1895)
figures under the Gymnodinium helix Pouchet two distinct forms. His figures
771s, plate 24, agree in all essential details with Pouchet’s species. His figure
77., however, is distinct in shape, torsion, and formation of the posterior end of
the body. Both of these forms we have found in our material at La Jolla,
and have no difficulty in separating them. His figure 77; we therefore reject
from Cochlodinium helix and place it in our new species, C. schuettt.

Comparisons.—This species, like C. cavatum sp. nov. (fig. HH, 10), shows
the greatest extent to which the mobility of the posteroventral portion of the
ody is developed in this genus. It probably lies in the direct line of evolution
which has produced Proterythropsis, and Hrythropsis (fig. T) with this region
of the body still further differentiated in the tentacular recess and the tentacle
or prod. It belongs between C. convolutwm (fig. HH, 5) and C. cavatum (fig.
HH, 10), as shown by the degree of asymmetry of the body.

Cochlodinium lebourae sp. noy.
Plate 2, figure 23; text figure HH, 7

DraaNnosis.—A small species with ellipsoidal body, its length 1.66 transdiam-
eters; girdle a descending left spiral of 1.7 turns, displaced 0.83 transdiameters ;
suleus with apical and antapical loops, and torsion of 1.5 turns; color, pale
lumiere green. Length, 50". Pacific off La Jolla, California, July.

DrscripTion.—The body is elongate, subellipsoidal, contracted posteriorly, somewhat con-
stricted by the girdle, nearly circular in cross-section, its length 1.66 transdiameters at the widest
part below the middle. Both apices are broad, the anterior rounded, the posterior notched by
the suleus. The epicone is considerably larger than the hypocone, its length being greater by
0.23 of itself. It is elongate hemispherical in shape with a length from the proximal and distal
ends of the girdle of 0.3 and 0.84 respectively of the total length of the body. Its posterior
portion consists of a narrow band tapering to a slender point distally. The hypocone is more
irregular in shape and consists of a wide band which makes slightly more than one turn around

the body and a rounded distal portion which is broadly excavated on the ventral surface by the
distal end of the suleus. The most posterior segment of the hypocone is only 0.6 of the width
of the one above it.

The girdle is a descending left spiral of 1.7 turns and a displacement of 0.83 transdiameter.
The proximal and distal portions of its spiral form angles of about 10° with the transverse plane,

372 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

steepening to about 30° in the middle part of its course. The furrow has a width of about 0.05
transdiameter and is deeply impressed with overhanging borders. With the suleus it constricts
the body somewhat, giving to it a lightly lobed outline.

The sulcus invades the epicone in a wide loop which terminates at the right side of the apex.
It makes an abrupt turn to the left after passing the anterior flagellar pore, and sweeps around
the body spirally with a torsion of 1.5 turns in reaching the antapex.. It is narrow anteriorly
and in the intercingular area, widening posteriorly to about three times the width of the girdle.
Its constriction of the body is somewhat less than that of the girdle. The anterior flagellar pore
is found at the anterior junction of the girdle and suleus, the posterior pore about one trans-
diameter beyond the distal junction, thus placing it on the same side of the body as the anterior
pore.

The nucleus is a subellipsoidal body filled with fine, moniliform chromatin strands following
its longer axis. It is located in the posterocentral part of the body, slightly oblique to the
transverse plane. Its major and minor axes are about 0.63 and 0.43 transdiameter in length
respectively.

The long sacklike pusules opening into the two flagellar pores are connected at their extrem-
ities by a slender canal. The cytoplasm is very clear and transparent and contains food bodies
and numerous blue-green oil globules in the peripheral zone. The general color of the organism
is pale lumiere green. It was enclosed in a thin-walled, slightly distended, hyaline eyst.

Drvensions.—Length, 50+; transdiameter, 30; axes of nucleus, 19” and 13+;
length of cyst, 58.

OccURRENCE.—A single individual was observed July 20, 1917, taken in a
surface haul at the end of the pier at the Biological Station at La Jolla,
California.

ComParIsons.—This species belongs to the subgenus Cochlodinium, and in
its type of girdle and torsion is not unlike C. citron (fig. HH, 12), but lacks its
rhabdosomes and has a more contracted antapex.

Named after Miss Marie Lebour, the investigator of the Gymnodinioidae
of British waters.

Cochlodinium miniatum sp. nov.
Plate 10, figure 107; text figure GG, 6

Dracnosts.—A large species with ellipsoidal-fusiform body with minute
apical and larger antapical process, its length 2.4 transdiameters; epicone and
hypocone subequal; girdle with 1.5 turns, displaced 0.6 total length; sulcus ab-
ruptly looped about apex, extending nearly to antapex; nucleus with peri-
nuclear zone; surface of epicone and hypocone unequally striate; pale green
yellow blotched with scarlet. Length, 2054. Paecifie off La Jolla, California,
July.

Description.—The body is elongated ellipsoidal-fusiform in outline, circular in cross-section,
its total length about 2.5 to 2.4 transdiameters (1.7 in contracted forms) at the widest part.
Excluding the apical and antapical prolongations, the ellipsoidal midbody has its major axis
about twice its minor one and is almost symmetrical, being somewhat more tapering posteriorly
and locally modified by the constricting effect of the furrows. The dorsoventral and trans-
diameters are equal and the epicone and hypocone are nearly so. The steep spiral course of
the girdle makes proportional measurements complicated. On its left side its length is 0.5 and
on the right 2 transdiameters. The apex is a small conical point about a girdle width in
diameter and height, partially encircled by the faintly developed anterior end of the suleus.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 373

The hypocone on its left side has a length of 1.85 and on its right of 0.45 transdiameters. It is
thus a trifle smaller than the epicone.

The girdle is a descending left spiral of 1.5 turns, displaced about 0.6 of the total length of
the body. It turns posteriorly at an angle of about 45° with the transverse plane, but the angle
gradually becomes less, the latter part of its course having a slope of 30°. The furrow has a
width of about 0.06 transdiameter and is deeply impressed with its trough undereutting the
anterior border. The anterior end of the suleus forms an apical loop which passes around the
short anterior process at the apex terminating on the right side. It passes posteriorly as a very
slender, faintly developed furrow, until it reaches the proximal end of the girdle, where it
suddenly expands and for the rest of its course has a width somewhat more than half the width
of the girdle, with a deeply impressed furrow, fading out before reaching the antapex. The inter-
cingular portion makes a turn of 0.5 transdiameter. The complete torsion is difficult to estimate,
as the anterior loop reverses its usual direction and passes from right to left around the apical
process, turning again to the left in the usual direction near the anterior pore region. The
posterior portion also swings to the right beyond the posterior pore. The anterior and posterior
flagellar pores are located at the anterior and proximal junctions of the girdle and sulcus
respectively.

The nucleus is a spheroidal body lying near the center, slightly posterior to the midplane.
It is differentiated into two zones, an outer, clear, hyaline perinuclear zone and an inner region
filled with coarse moniliform chromatin strands. The outer zone is narrow, about 0.07 of the
total transdiameter of the nucleus in width, and is composed of alveoli surrounded by a double-
contoured membrane. The axis of the nucleus is about 0.5 transdiameter of the body in length.

The cytoplasm is clear and transparent and pale greenish yellow in color. A number of
food vacuoles were present, one of irregular shape and of a pale brown color near the posterior
pore close beside the nucleus, and several spherules of varying sizes, bluish or pink in color,
scattered through the anterocentral part of the body. Nutrition, as in most if not all of the
species of Cochlodinium, is holozoic. In the posterior region were two long, slender, blue-green
rhabdosomes, about 0.8 transdiameter in length, lying in the plane of the surface with their ends
at the antapex.

The surface is finely striate with equidistant, blue-green, broken lines, about 45 on the
ventral face of the epicone at the girdle. These are about four times as numerous on the epicone
as on the hypocone. Irregular splashes of scarlet pigment are scattered through the peripheral
layer in close relation to the striae, but not confined to single lines as in Gyrodinium corallinum
(pl. 10, fig. 117). These are confined almost exclusively to the epicone in the individual figured.

Dimenstons.—Length, 175-205; transdiameter, 85; axis of nucleus, 45-.

OccURRENCE.—Taken on July 9, 1907, in a haul made with a No. 12 net
from 120 meters to the surface, 2.5 miles off La Jolla, California, in a surface
temperature of about 20° C,

Comparisons.—In its red pigment and type of nuclear structure this species
resembles Gyrodinium corallinum (pl. 10, fig. 117), G. virgatum (pl. 10, fig.
112), and Gymnodinium rubrum (pl. 8, fig. 86). With Cochlodinium strangu-
latum (fig. GG, 8) it is the largest species in this genus and next to the largest
thus far described in the Gymnodinioidae, Gymnodinium cucumis (fig. Y, 16),
210 in length, alone exceeding it.

It forms the type of a large group of species of the subgenus Cochlodiniwm
characterized by a torsion of the body represented by 1.5 turns of the girdle.
This amount of torsion places the group near the genus Gyrodinium, and in
the case of Cochlodinium minatum this relationship is still further strength-
ened by the striate surface, characteristic of many species of Gyrodinium.,

.

374 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Cochlodinium pellucidum Lohmann
Text figure GG, 15

Cochlodinium pellucidum Lohmann (1908), p. 264, pl. 17, fig. 21.
C. pellucidum, Paulsen (1908), pp. 104, 105, fig. 145.

C. pellucidum, Ostenfeld (1913), p. 338.

C. pellucidum, Lebour (1917b), p. 197.

DiaGgNnosis.—A small species with slightly obovoidal body, its length 1.77
transdiameter ; girdle a descending left spiral of 1.5 turns, displaced 1.09 trans-
diameters; suleus (?); colorless. Length, 39#. Baltic near Kiel, Germany,
June.

DeEscrIPTION.—The body is elongate obovoidal with broad apices, widest near the middle, its
length 1.77 transdiameters at the widest part. The epicone and hypocone are subequal. In
Lohmann’s figure the suleus is omitted entirely, and the girdle drawn as a spiral of 1.5 turns.
It is difficult to determine the ends of the girdle, as both the proximal and distal portions of the
furrow may be parts of the sulcus. In our deseription we have taken the length of the girdle
as 1.5 turns. This would give to the epicone a length from the proximal and distal ends of the
girdle of 0.12 and 0.79 respectively of the total length of the body. The hypocone is slightly
narrower than the epicone and is less symmetrical.

The girdle is a descending left spiral of 1.5 turns, its proximal and distal ends distant from
the apex about 0.12 and 0.79 respectively of the total length of the body. The furrow is narrow
and deeply impressed.

The cytoplasm contains numerous minute spherules seattered through the peripheral zone.
Tn the posterocentral part is a small spheroidal body. Anterior to this is a somewhat irregular
ellipsoid, yellow ochre in color, which is probably a food body. In the anterocentral part is
another body, dark, slightly smaller than the food mass and ellipsoidal in shape. This is
probably the nucleus, though no clue to its identity is given. The organism is colorless.

Dmvenstons.—Length, 394; transdiameter, 22+.

OccuRRENCE.—Figured by Lohmann (1908) from the Baltic Sea near Kiel,
Germany, in June.

Comparisons.—With the sulcus omitted the description of this species is
somewhat inadequate. It is, however, tentatively placed in the C. strangulatum
group of the subgenus Cochlodinium.

Cochlodinium pirum (Schiitt) Lemm.
Plate 9, figure 101; text figure GG, 3

Gymnodinium pirum Sehiitt (1895), p. 166, pl. 23, fig. 76,_,.
Cochlodinium pirum, Lemmermann (1899), p. 360.
Gymnodinium pirum, Entz (1907), p. 11.

G. dirum, Entz (1909), p. 246, lapsus.

Diacnosis.—Medium sized species; body obovoidal; wider posteriorly;
length, 1.6-1.7 transdiameters, girdle a descending left spiral of 1.5 turns, dis-
placed 0.5-0.6 total length; sulcus with torsion of 0.5 turn; surface striate (?) ;
color, yellow ochre. Atlantic; Pacific off La Jolla, California, July.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA By

oO

Description.—The body is ovoidal, somewhat flattened ventrally, widest 0.65 total length
from apex. The dorsoventral diameter is 0.84 the transdiameter, which is greatest slightly
below the middle. The epicone exceeds the hypocone by 0.15—0.20 total length. Its length at
the proximal and distal ends of the girdle is 0.28 and 0.86 total length respectively. It is rotund,
subconieal (40°), with rounded apex. The hypocone has a length at the proximal and distal
ends of the girdle of 0.72 and 0.14 total length respectively. It is wider and fuller than the
epicone, flattened hemispherical, and its postmargin is indented by a broad suleal notch.

The girdle forms a descending left spiral of 1.5 turns. It leaves the anterior junction with
the suleus at 0.28—0.39 total length from the anterior end and is but slightly deflected in the
first 0.5 turn, then steepens to 30°—85°, increasing to 45° near the distal end. Its total dis-
placement is 0.50-0.57 of the total length. The furrow is moderately impressed, with distinctly
lined edges and slightly overhanging lips. Its width is about 0.1 transdiameter. The sulcus
begins near the apex on the epicone, runs thence posteriorly with slight torsion to its anterior
junction with the girdle 0.28—0.39 total length from the anterior end, descends with increasing
torsion in a steep left spiral of about 0.5 turn to the distal junction 0.14-0.18 total length from
the posterior end. In the lower part of the intercingular section it is very close to the girdle.
It is a narrow trough about 0.5 width of the furrow and does not lie in a depression of the
surface produced by its constriction. Below the posterior junction it flares widely and broadly
notches the postmargin. The anterior flagellar pore lies at the anterior junction and the
posterior pore some distance below the posterior one. The transverse flagellum runs the whole
length of the girdle and the posterior one is less than a transdiameter in length (in the cyst).

In both Sehiitt’s (1895) specimen and our own the nucleus was peculiar in that it was stout
reniform in outline with more or less concentric, spiral, moniliform chromatin threads. It lies
to the right and near the middle of the body or below it. Its major and minor axes in our
specimen were 0.9 and 0.5 transdiameter respectively, in Schiitt’s specimen (1895), 0.54 and
0.40 respectively. In Schiitt’s figure (1895) there is a food mass anteriorly and a cluster of
twisted rodlets near the apex. The plasma of our specimen was clear, without formed contents
of either of these kinds. An anterior sack-shaped pusule opens anteriorly into the pore of the
transverse flagellum. No posterior pusule was noted. Sehiitt (1895) apparently figures both,
but does not label them. In the peripheral plasma is a layer of circular ochraceous platelets
resembling chromatophores in color. They are uniform in size, regularly distributed and are
about 0.5 furrow’s width in diameter.

We find no striae on our specimen on close examination. Schiitt figures 15 across the ventral
face, following the torsion of the body and sparingly beaded. Both Schiitt’s specimen and our
own were enclosed in a large, spheroidal, double-contoured, hyaline cyst, 1.5 length of the body
in diameter.

Dimensions.—Leneth, 60-84; transdiameter, 35-50“; axes of nucleus, 32
and 214, 27 and 204. The second figure in each case is of Schiitt’s specimen.

ACTIVITIES.—Our specimen was first seen at 4 P.M. in a plankton catch taken
at8a.M. At 6 p.m. it was still active, circling within the cyst incessantly without
a single observed rotation, in anticlockwise circles. The transverse flagellum
was active during this circling.

OcCURRENCE.—This was first observed July 5, 1917, in a haul 6 miles off
La Jolla, California, from 80 meters to the surface and in a surface temper-
ature of 21°9 C. It was also observed in hauls made July 23, 6 miles offshore,
from 80 meters to the surface, on July 27, 4 miles offshore, from 80 meters,
and on August 20, 0.75 mile offshore in temperatures ranging from 20°8 © to
21°9 C.

376 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

ComParIsons.—This species is a member of the C. miniatum group of the
subgenus Cochlodinium. It is very near C. convolutum (fig. HH, 5), but has
less torsion, 0.5 instead of 0.6, and less displacement of the girdle, 0.5-0.6 instead
of 0.6 total length, and is more ochraceous and less greenish in color. It is
larger than C. schuetti (fig. HH, 2) and tapers more anteriorly.

Cochlodinium pulchellum Lebour
Plate 7, figure 80: text figures HH, 13, 14, 16

Cochlodinium pulchellum Lebour (1917b), p. 197, fig. 14.
C. pulchellum, Kofoid and Swezy (1917), pp. 90-91, figs. 3, 4.

DraGcnosis.—A minute species with body symmetrically fusiform, deeply
constricted by girdle and suleus; its length 2.9 transdiameters; girdle a de-
scending left spiral of 3.2 turns, displaced 0.76 total length; sulcus with torsion
of 0.5 turns; color, pale green to glaucous blue. Length, 38. Atlantic, Ply-
mouth Sound; Pacific off La Jolla, California, July, August.

DescripTion.—The body is slender, nearly symmetrically fusiform, widest at the middle,
very deeply incised and constricted by the girdle and suleus, its length 2.9 transdiameters at
the widest part near the middle. The body tapers a trifle more posteriorly than anteriorly.
The epicone exceeds the hypocone in size, its length being greater by 0.1 total length. It has a
hemispherical apex slightly deflected to the left, and a length at the proximal and distal ends
of the girdle of 0.18 and 0.88 respectively of the total length of the body. The hypocone is about
half the width of the epicone anteriorly because the sulcus lies nearer the upper than the lower
turn of the girdle and follows its course around the body. Below the distal junction of girdle
and sulcus it enlarges into the hemispherical antapex, which has no suleal notch in the post-
margin.

The girdle joins the antapex about 0.18 of the total length of the body from the apex. It
sweeps around the body in a descending left spiral of 3.2 turns which steepens from 20° to 30°
below the horizontal beyond the first 0.5 turn and joins the suleus distally about 0.88 of the
total length of the body from the apex. Its total intercingular displacement is 0.76 of the total
length. It lies in a wide, deep depression with smooth overhanging lips on both sides. The
anterior flagellar pore is located at the anterior junction of the girdle and sulcus, the posterior
pore slightly beyond the posterior junction.

The sulcus invades the epicone in a short curved loop directed toward the left of the apex.
Below the anterior pore it sweeps down in a gradually steepening descending left spiral of 2.5
turns, terminating near the antapex in a small, oblique, antapical loop which makes 0.5 turn
beyond the posterior junction with the girdle. It forms a narrow, deep trough with high,
rounded sides.

The nucleus is spheroidal and median or somewhat postmedian in position. . Its chromatin
contents could not be traced. Its diameter is about 0.5 transdiameter in length.

The cytoplasm is coarsely granular and contains from few to numerous, minute oil droplets
and sometimes highly refractive greyish bodies. The color ranges from a light pale cendre
green to glaucous blue, diffused throughout the eytoplasm. No striations or other surface
markings could be detected.

Two individuals were observed within very delicate, transparent cysts slightly larger and
conformable to the outline of the body. Both were undergoing binary fission with the nuclei
divided in each ease.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 377

Divenstons.—Length, 30-40; transdiameter, 13-18; diameter of nucleus,
7-9p.

OccurRENCE.—The first individual of this species was taken July 20, 1917,
in a haul made 6 miles off La Jolla, California, from 80 meters to the surface
in a surface temperature of 20°5 C. The dividing specimen was taken in a
similar haul 4 miles off La Jolla in a surface temperature of 20°8 C. The
species was also taken August 3, 6.5 miles off La Jolla in a haul from 80 meters
to the surface at 21°2 C and August 13, 0.75 mile offshore in a haul from 83
meters to the surface at about 22°5 C. Miss Lebour (1917) reports a single
individual in August, 1915, from the plankton of Plymouth Sound from a
water sample taken from a depth of 7 fathoms.

- ActivitrEs.—Encysted forms are incessantly active, rotating within the cyst,
both flagella being active.

CoMPARISONS.—Miss Lebour describes her specimen as colorless, fusiform
in shape, with a girdle of three turns and sulcus making over one turn around
the body. She states that its length is 50» and that of the cyst 650 [sic].
These dimensions do not agree with the measurements of her figure which has
a length of 604 and a width of 21+, while the length of the cyst is only 854. Her
figure is evidently reversed, as it shows the organism with a complete reversal
of organelles, its girdle and sulcus having a right instead of left descending
course (see Kofoid and Swezy, 1917). The sulcus or longitudinal furrow makes
2.5 turns around the body rather than ‘‘over one’’ turn, as she has stated.

This is the smallest species of Cochlodinium, although not the shortest, thus
lving at the opposite extreme from C. augustum (fig. HH, 15), the nearest
related species and the only other one in the subgenus Polydinium. C. pul-
chellum has 0.5 less turn of the sulcus than C. augustwm and an oblique instead
of a vertical antapical extension of the sulcus beyond the posterior junction
with the girdle. Otherwise the principal difference between the two species is
in size.

Cochlodinium radiatum sp. noy.
Plate 6, figure 67; text figure GG, 12

Dracnosis.—This is a medium sized species with rotund ellipsoidal body,
its length 1.28 transdiameters; girdle a descending left spiral of 2 turns, dis-
placed 0.75 transdiameter; sulcus with torsion of 1 turn; color, glaucous blue
splashed with aster purple. Length, 68«. Pacific off La Jolla, California, July,
August.

DescriptioN.—The body is of robust habit, rotund ellipsoidal in shape, cireular in cross-
section, with broad rounded apices, its length 1.28 transdiameters at the widest part at the
middle. The epicone exceeds the hypocone in size, its length being greater by 0.3 of its own
length. It is subhemispherical in shape, with a length from the proximal and distal ends of
the girdle of 0.33 and 0.91 respectively of the total length of the body. The posterior portion
is a wide band which diminishes distally to a slender point after making a nearly complete turn
about the body. The anterior part of the hypocone is wider than the corresponding part of the
epicone, becoming narrower near the posterior pore. It is broadly rounded distally with the

37 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

ao

antapex scarcely notched by the distal end of the suleus. The antapex is somewhat broader
and more flattened than the apex.

The girdle has a distance from the apex at its proximal and distal ends of about 0.33 and
0.91 respectively of the total length of the body. It is a descending left spiral of two turns
with a displacement of 0.75 transdiameter. The first 1.2 transdiameter of its course is in a
nearly transverse plane, turning posteriorly with an angle of 30° to 20° from the transverse
plane, the latter 0.5 transdiameter again rising to a nearly transverse direction. It meets the
sulcus distally at a distance from the antapex of less than 0.1 of the total length of the body.
The furrow varies slightly in the width, being widest in the middle, where its width is about
0.04 transdiameter, and narrower at its proximal and distal ends, and is deeply impressed,
undercutting its anterior lip and sloping gradually out to the posterior one. The body is
slightly constricted by the furrow on the left side and on the right the borders are slightly
elevated above the surrounding surface.

The sulcus begins near the apex as a wide, shallow furrow, which passes posteriorly as a
descending left spiral of slightly more than one turn. After passing the anterior pore it
contracts to less than half its width above, expanding again after passing the posterior pore
into a broad, shallow trough, which fades out at the antapex. The anterior and posterior pores
are located at the anterior and posterior junctions of the girdle and sulcus respectively.

The nucleus is elongate ellipsoidal in form, located on the right side of the posterocentral
part of the body. It is filled with fine, moniliform chromatin strands. Its major and minor
axes are about 0.6 and 0.27 transdiameter in length respectively.

A long, slender pusule connects the anterior and posterior flagellar pores, forming a complete
channel between the two openings. The cytoplasm is finely granular and a mixture of pearl
grey and light glaucous blue in color. The specimen figured was unusually free from oil drop-
lets. One large food mass, green and yellow ochre in color, was present in the anterior region.
There were two groups of long, slender, tapering, greenish, radial rodlets, one of which was in
the anterior part near the food mass and the other in the posterior region. Lying in the
periphery, and scattered over the entire body, are irregular splashes of pigment, aster purple
in color, the larger masses showing a deeper tone than the smaller, lighter ones. A thin hyaline
eyst, slightly larger than the body, enclosed one individual.

Dimensions.—Length, 68-78; transdiameter, 52-60«; axes of nucleus,
33-36 and 14+; length of radial rodlets, 12-18.

OccuRRENCE.—The specimen figured was taken July 25, 1917, with a No.
25 silk net in a haul 11 miles off La Jolla, California, from 80 meters to the
surface and in a surface temperature of 21°2 C. A second individual was
taken August 10 with the same apparatus 1 mile off La Jolla in a haul from
50 meters to the surface and in a surface temperature of 21°9 C.

Compartisons.—The most striking feature of this species is its eolor of
irregular, chromatophore-like splotches of aster purple. This is unlike that
of any other species of the genus and finds its counterpart in Gymnodiniwm
violescens (pl. 6, fig. 69) and G. lineopunicum (pl. 6, fig. 65). No observations
of the motility of the pigment were made, but it is probable that it possesses that
characteristic in common with the pigment of G. lineopunicum and Gyrodinium
ochraceum (pl. 7, fig. 76).

Cochlodinium radiatum falls in the C. citron group of the subgenus Cochlo-
dintum, and lies midway between C. virescens (fig. HH, 11) and C. citron (fig.
HH, 12) in the amount of torsion of the body as shown in the length of the
girdle.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 379

Cochlodinium rosaceum sp. nov.
Plate 8, figure 85; text figure HH, 4

DraGnosis.—A medium sized species with ellipsoidal body, its length 1.48
transdiameters; girdle a descending left spiral of 1.5 turns, displaced 0.85 trans-
diameter; sulcus with torsion of 0.5 turn; color, rose red. Length, 634. Pacific
off La Jolla, California, July.

DEscripTIoN:—The body is rotund ellipsoidal, with broad apices, nearly circular in cross-
section, the dorsal side more convex than the ventral, its length 1.48 transdiameters at the
widest part. The epicone exceeds the hypocone in size, its length being greater by 0.26. The
epicone is subhemispherical in shape, with a length from the proximal and distal ends of the
suleus of 0.28 and 0.88 respectively of the total length of the body. The hypocone is rounded,
with broad, somewhat flattened antapex indented by a wide suleal notch.

The girdle is a descending left spiral lying at a distance from the apex of 0.28 and 0.88
respectively of the total length of the body. In the first transdiameter of its course it is deflected
anteriorly, gradually turning posteriorly at an angle of about 35° with the transverse plane.
At its distal end its direction is nearly transverse. The furrow is narrow, varying somewhat
in width, its average about 0.04 transdiameter, and is rather shallow, with smooth borders. The
sulens arises near the apex and extends posteriorly in a left, spirally deflected course with a
torsion of shghtly more than 0.5 turn. The furrow is narrow in width and shallow, but in the
intercingular area it lies at the base of a deep constriction of the body, and expands at the
antapex in a broad suleal notch. In figure 85, plate 8, the body is distended by an ingested
Pouchetia, and the outline is somewhat distorted. Figure HH, 4, gives the appearance of the
normal individual. The anterior and posterior flagellar pores open at the anterior and posterior
junctions respectively of the girdle and sulcus, lying on opposite faces of the body.

The nucleus is an ellipsoidal body filled with moniliform chromatin strands. It is located
in the anterocentral part of the body. Its axes are about 0.5 and 0.3 transdiameter in length
respectively.

Small club-shaped pusules are present at either or both pores. The cytoplasm is very clear
and transparent, without granulations. Scattered irregularly throughout were salmon-pink
globules, evidently containing the same fluid as found in the pusules. The individual shown
in figure 85, plate 8, had ingested a Pouchetia, probably ruwbescens. This was enclosed in a
food vacuole and still preserved part of its girdle, the nucleus and ocellus and its rose coloring.
The general color of the organism is very dilute rose red, diffused through the cytoplasm. A
few granules of rose red were collected near both apices with larger masses of the same coloring
in the central region. A cyst had been recently formed about the body, only slightly larger
than itself and closely following its outlines.

DimMenstons.—Length, 62-694; transdiameter, 48-524; axes of nucleus,
20-23» and 16-18.

OccURRENCE.—T wo individuals were taken July 12, 1917, with a No. 25 silk
net ina haul made 6 miles off La Jolla, California, from 80 meters to the surface
and in a surface temperature of 20°5 C.

Comparisons.—Cochlodinium rosaceum forms one of a relatively large
number of species in the Gymnodiniidae distinguished by rose-red pigment.
These are found in Gymnodinium, Gyrodinium, as well as in Pouchetia.

It falls within the subgenus Glyphodinium, being one of the least specialized
members of that group, as shown in the slight ventral excavation of the body.
It is the only known member of this subgenus with a red color.

380 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Cochlodinium schuetti sp. nov.
Plate 1, figure 8; text figure HH, 2
Gymnodinium helix Schiitt (1895), in part, pl. 24, fig. 77,.

Dracnosts.—A medium sized species with rotund ellipsoidal body, its length
1.47 transdiameters; girdle a descending left spiral of 1.5 turns, displaced 0.52
transdiameter; sulcus with torsion of 0.5 turn; color, pale greenish yellow.
Length. 59#. Pacific off La Jolla, California, July.

DescripTion.—The body is rotund ellipsoidal in shape with broad apices, nearly circular in
cross-section, its length 1.47 transdiameters at the widest part. The epicone and hypocone are
subequal in size, though the total length of the former is slightly greater than the length of the
latter. The epicone is subhemispherical in shape with broad apex. It has a length from the
proximal and distal ends of the girdle of 0.38 and 0.75 respectively of the total length of the
body. The hypocone is somewhat broader than the epicone, subtruncate posteriorly with the
antapex indented by the suleal notch.

The girdle is a descending left spiral of 1.5 turns and a displacement of 0.52 transdiameter.
The distance of its proximal and distal ends from the apex is about 0.38 and 0.75 respectively
of the total length of the body. The first 0.5 transdiameter of its course is deflected anteriorly
at an angle of about 30°, gradually changing to a transverse direction on the left side, turning
posteriorly on the dorsal face and again flattening to a transverse plane at its distal end. The
furrow has a width of about 0.05 transdiameter and is deeply impressed with rounded, over-
hanging borders.

_ The sulcus may invade the epicone in a shallow loop which soon fades out or it may stop at
its proximal junction with the girdle. Its width is somewhat less than that of the girdle in the
intercingular area, expanding greatly posteriorly and forming a wide, rather shallow suleal
noteh at the antapex. It is deeply constricted in the intercingular area, resulting in a lobed
appearance of the ventral surface. The anterior and posterior flagellar pores are located at
the anterior and posterior junctions of the girdle and sulcus respectively. ;

The nucleus is an ellipsoidal body filled with fine, moniliform chromatin strands following
its longer axis. It is located in the posterocentral part of the body near the dorsal surface.
Its major and minor axes are about 0.57 and 0.4 transdiameter respectively.

Pusules may be present at either or both pores. In the individual figured the two pusules
were connected by a long slender canal, forming a tubular connection between the two pores.
The cytoplasm is very clear and transparent with numerous blue-green droplets seattered
through the peripheral zone. The anterior portion of the body was occupied by a large food
mass sea-foam yellow in color. The color of the organism is a diffused pale greenish yellow.
A large, thin-walled, hyaline cyst enclosed each of the individuals observed.

Drmenstons.—Length, 59-74"; transdiameter, 40-50; axes of nucleus, 23
and 16r.

OccuURRENCE.—Two individuals were taken July 20, 1917, 6 miles off La
Jolla. California, with a No. 25 silk net, in a haul from 80 meters to the surface
and in a surface temperature of 21° C.

Synonymy.—Schiitt (1895) figured, as Gymnodinium helix Pouchet, two
distinct forms. The first of these, shown in his figures 77:-;, plate 24, is evidently
Pouchet’s species. His figure 77s, however, differs from the others in the shape
of the body, amount of torsion, and the posterior arrangement of girdle and

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 381

sulcus in their relation to the twisted posterior portion of the body. Both of
these forms we have found in the plankton at La Jolla and have no difficulty
in separating them. We therefore propose to separate his figure 77. as a new
species, C’. schuetti. The elongate nucleus in Schiitt’s figure is evidently that
of a predivision stage.

CoMPARISONS.—This species belongs with the subgenus Glyphodinium and
lies midway between C. geminatum (fig. GG, 1) and C. vinctum (fig. HH, 3),
near the beginning of the series showing an increasing curvature and distortion
of the hody. The anteroposterior plane passing from apex to antapex is more
ventrad in position in C. schuetti than in C. geminatum and less so than in C.
vinctum, nearly equaling that of C. resaceum (fig. HH, 4) in this respect.

Cochlodinium scintillans sp. nov.
Plate 10, figure 113; text figure GG, 11

Diacnosts.—A small species with subellipsoidal to biconical body, its length
1.4 transdiameters; girdle a descending left spiral of 1.5 turns, displaced 0.74
transdiameter ; sulcus with apical loop and torsion of 0.5 turn; color, pearl grey
with reddish tones. Length, 38. Pacific off La Jolla, California, July.

DescripTION.—The body is asymmetrically ellipsoidal approaching biconical, tapering at
both apices, circular in cross-section, its length 1.4 transdiameters at the widest part, which is
at the middle. The epicone is considerably larger than the hypocone, having a greater trans-
diameter as well as greater length. It has the shape of a cone of about 80° with the left side
slightly elevated, deflecting the blunt apex somewhat to the right. It has a length on the left and
right sides of 0.26 and 0.84 respectively of the total length of the body. The hypocone is sub-
conical, its angle varying from 50° at the antapex to about 80° anteriorly, its sides slightly
coneave. It is narrower than the epicone with a more slender pointed antapex.

The girdle is a descending left spiral of 1.5 turns and a displacement of 0.74 transdiameter.
The distanee from the apex of the proximal and distal ends is about 0.26 and 0.84 respectively
of the total length of the body. The furrow has a width of about 0.07 transdiameter, and is
deeply impressed with smoothly rounded borders. The suleus forms a loop on the epicone,
terminating below the apex on the left side. After passing the anterior flagellar pore it is
deflected to the left with a torsion of 0.5 transdiameter in the intercingular part of its course,
beyond which it passes posteriorly to within a short distance of the antapex. Its width is about
one-third that of the girdle and the furrow is relatively deeply impressed. The anterior and
posterior pores are located at the anterior and posterior junctions of the girdle and sulcus
respectively.

The nucleus is reniform in shape and filled with fine, parallel, moniliform chromatin strands
following its longer axis. Its major and minor axes are about 0.51 and 0.29 transdiameters in
length respectively.

The cytoplasm is finely granular with a number of greenish oil droplets scattered through it.
In the posterior region was a large, spherical vacuole filled with a pink fluid. Below this was
a rounded body, orange rufous in color, and near the apex a smaller one of jasper red. The
general color of the cytoplasm is pearl grey with tints of red showing through it. This form,
like so many of the Gymnodinioidae, showed a striking play of color through the cytoplasm,
which is almost impossible of analysis and still harder to reproduce adequately.

382 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Divensions.—Length, 384; transdiameter, 27+; axes of nucleus, 15» and 8.

OccURRENCE.—This was taken July 17, 1917, with a No. 25 silk net, 5 miles
off La Jolla, California, in a surface haul and in a surface temperature of 20° C.
A second individual was observed July 27 in a haul 4 miles off La Jolla, from
80 meters to the surface and in a surface temperature of 21°4 C,

CoMPARISONS.—This species lies on the borderline between Cochlodinium
and Gyrodinium, more nearly approaching the latter than perhaps any other
species of this genus. It is the only biconical species in the genus. It belongs
in the C. miniatum group of the subgenus Cochlodinium.

Cochlodinium strangulatum Schiitt
Text figure GG, 8

Gymnodinium strangulatum Schiitt (1895), pl. 22, fig. 72.
Cochlodinium strangulatum, Schiitt (1896), pl. 5, fig. 7.
C. strangulatum, Lemmermann (1899), p. 360.

C. strangulatum, Cavers (1913), pp. 182, 183, fig. 9,,_,,.

Dracnosis.—A large species with ellipsoidal body, its length 1.8 transdiam-
eters, girdle a descending left spiral of 1.6-1.75 turns, displaced 1.04 trans-
diameters; sulcus with apical and antapical loops and torsion of 0.8 turn; sur-
face striate. Length, 198. Atlantic (?) or Bay of Naples.

DescripTion.—The body is robust, irregularly ellipsoidal with the one face forming an almost
straight line, the other surface convex. The apices are broadly rounded. The epicone and
hypocone are subequal. The epicone has a length above the proximal part of the girdle of 0.22
and from its distal extremity of 0.81 respectively of the total length of the body. It is sub-
hemispherical in outline, convex ventrally, slightly so dorsally, with a broad, blunt apex excen-
trically placed towards the ventral side. It expands below the anterior flagellar pore region
to nearly 1.4 of its width at that point, the expansion being entirely on the dorsal side. The
hypocone is somewhat broader than the epicone. Its sides are rounded with a distinctly
acuminate antapex which is ventrad from the midplane of the body.

The girdle joins the proximal end of the suleus at about 0.22 of the total length of the body
from the apex. It follows a descending left spiral course which makes 1.6-1.75 turns before
joining the distal end of the suleus at about 0.18 of the total length of the body from the
antapex. I is relatively wide and deeply impressed with smooth, rounded borders. The position
of the flagellar pores was not indicated in Schiitt’s figures.

The sulcus invades the epicone as a wide loop, terminating near the apex on the dextrodorsal
surface. Posteriorly it follows a descending spiral course which makes about 0.8 turn in
reaching its posterior junction with the girdle, beyond which it invades the hypocone in a
curved line which terminates at the sinistrodorsal side of the antapex. It is broad and deeply
imbedded, with high rounded borders.

The nucleus is spheroidal, and is located slightly posterior to the central part of the body.
It shows two clearly differentiated regions, a peripheral clear zone and an inner portion. Its
axis is about 0.4 transdiameter in length.

The cytoplasm is alveolar with numerous small spherules in the peripheral region overlying
large alveoli. A globular pusule in the anterior region is connected with the anterior flagellar
pore, presumably, by a long slender canal. The color of the organism was not noted. The

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 383

surface is minutely striate with closely set, equidistant striae, approximately equal in number
on both epicone and hypocone and apparently about 60 across one face. In his figure 72, plate
22, Schiitt (1895) shows a portion of an individual fixed with Flemming’s solution and stained
with haemotoxylin, from the posterior end of which stream long, pseudopodia-like strands of
protoplasm. These did not appear in the living animal, but required staining to make them
visible. They apparently have no definite place of origin and are probably artifacts, such as
are frequently found in stained material.

Dimensions.—Length, 198; transdiameter, 110”; axis of nucleus, 54.

OccurRENCE.—Figured by Schutt (1895) from material collected by the
Plankton Expedition, presumably from the Bay of Naples or the Atlantic.

SynonyMy.—This species was first described by Schiitt (1895) as Gymno-
dinium strangulatum, and later (1896) changed by him to Cochlodinium as the
type and only species of the genus when described. It is also the type species
of the subgenus Cochlodinium.

Comparisons.—This is one of the largest species in the genus, being exceeded
in size by only one species, C. minatum. It shares with this species the pecu-
liarity of having a perinuclear, hyaline zone, as well as a striate surface, but
differs from it in the absence of red pigment, shape of the body, and in having
a hemispherical instead of a pointed apex. The species is otherwise quite
isolated in the genus.

Cochlodinium turbineum sp. noy.
Plate 9, figure 99; text figure GG, 9

DraGcnosis.—This is a minute species with broad, obovoidal body, its length
1.04 transdiameters; girdle a descending left spiral of 1.5 turns, displaced 0.56
transdiameter ; sulcus with short apical loop and total torsion of 0.5 turn; color,
yellowish green. Length, 26, Pacific off La Jolla, California, July, August.

DEScRIPTION.—The body is broadly obovoidal in outline, circular in cross-section, its length
1.04 transdiameters at the widest part about the middle of the body. The anterior part of the
body is rotund, tapering posteriorly with the ventral face deeply constricted by the intercingular
suleus. The epicone greatly exceeds the hypocone in size, its length and transdiameter being
greater. It is broadly rounded anteriorly with a length from the proximal and distal ends of
the girdle of 0.31 and 0.88 respectively of the total length of the body. Its distal portion
becomes drawn out to a slender point. The length of the hypocone posterior to the distal
junction of the girdle and sulcus is about 0.05 of the total length of the body. The antapex is
notched by the distal end of the sulcus.

The distance of the proximal and distal ends of the girdle from the apex is about 0.31 and
0.88 respectively of the total length of the body. In the first 0.8 transdiameter of its course
the rotundity of the body throws it somewhat anteriorly, beyond which it turns posteriorly at
an angle of 30° to 40° with the transverse plane on the left side of the body, traversing the
right in a nearly transverse direction with another short posterior deflection to meet the sulcus.
The furrow has a width of about 0.05 transdiameter and is deeply impressed. The anterior
flagellar pore is located at the anterior junction of the girdle and sulcus and the posterior pore
at the posterior junction.

384 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The sulcus forms a short loop on the epicone, ending below the apex. Posterior to the
anterior pore it takes a descending left course which makes 0.5 turn in reaching the antapex.
It is narrow and deeply impressed with high-rolling borders. This with the girdle throws the
ventral surface into a series of three rounded lobes.

The nueleus is large, ellipsoidal and placed slightly anterior to the central portion of the
body. Fine, moniliform parallel chromatin strands traverse a course obliquely across its major
axis. Its major and minor axes are 0.6 and 0.48 transdiameter in length respectively.

The cytoplasm is very clear and transparent with but few inclusions. Near the periphery
are a number of refractive spherules and blue-green oil droplets. A food mass, yellow ochre
in color, was found in the center of the body adjacent to the nucleus. The color is mingled
yellow green and pearl grey.

DiMeEnsions.—Length, 26; transdiameter, 25; axes of nucleus, 15“ and 12,

OccURRENCE.—A single individual was taken July 25, 1917, with a No. 25
net, 11 miles off La Jolla, California, in a haul from 80 meters to the surface
and in a surface temperature of 21°8 C. Two individuals were taken August 8
in a haul 4 miles off La Jolla, from 80 meters to the surface and in a surface
temperature of 22°5 C.

Comparisons.—This is the shortest and the smallest species in the genus
Cochlodinium, and is most contracted posteriorly. Its rotundity, however,
makes it nearly equal in size to C. pulchelluim sp. nov. (fig. HH, 16), the latter
having a greater length but about half its width. It belongs in C. miniatwm
group of the subgenus Cochlodinium.

Cochlodinium vinctum sp. nov.
Plate 2, figure 15; text figure HH, 3

DraGnosis.—Medium sized species; body asymmetrically ovoidal or rotund,
dorsally arched, length 1.4 transdiameters, girdle a descending left spiral of
1.50-1.65 turns, displaced 0.57-0.62 total length, sulcus with anterior and pos-
terior loops, torsion 0.50—-0.65 turns; plasma very clear, pale glaucous blue,
sometimes tinged with yellow. Length, 50-75. Pacific off La Jolla, California,
July, August.

DerscripTION.—The body is asymmetrically ovoidal to rotund in shape, according to the view.
The more rotund forms may also owe their breadth in part to the great mass of cell inclusions
present in such individuals. The anterior end is often a trifle broader and rounded, the posterior
slightly narrower and also rounded, and the spiral ventral face deeply channeled and some-
what flattened, while the dorsal is arched, in the extreme condition almost hemispherical. The
epicone and hypocone are subequal. The epicone has a length at the proximal and distal ends
of the girdle of 0.18 and 0.65 respectively of the total length of the body. Its apex is sub-
hemispherical with the flatter slope on the right side. The hypocone has a length at the proximal
and distal ends of the girdle of 0.82 and 0.35, total length of the body. The antapex is sub-
hemispherical with the flatter slope at the morphological right side of the suleus. It is some-
times notched by the end of the sulcus.

The girdle joins the suleus anteriorly at 0.18 of the total length of the body from the apex.
It forms a descending left spiral of 1.6 turns, displaced about 0.57—0.62 diameter. It is deeply
impressed, especially on the left side, forming with the sulcus a series of deep lobes on the

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 385

sinistroventral face of the body. It is less deeply impressed on the dextrodorsal surface. Its
width is 0.08 transdiameter. The anterior flagellar pore opens at the anterior junction of the
girdle and suleus, the posterior pore at the posterior junction.

The suleus invades the epicone im a short, curved extension which terminates near the apex.
It passes posteriorly in the hollow of a very deep trough, making 0.50—-0.65 turn before meeting
the distal end of the girdle. Beyond the distal junction it widens to about twice its width above,
and terminates on the left side of the median line at or near the postmargin, sometimes with a
slight suleal notch. Its total length anteroposteriorly is about 0.9 of that of the body.

The nucleus is spheroidal to ellipsoidal and located in the posterior half of the body. About
ten moniliform chromatin strands traverse it spirally about its main axis. Its axes vary in
length from 0.40 and 0.32 to 0.5 and 0.3 transdiameter respectively.

A large sacklike pusule opens distally into each flagellar pore. In one individual their
proximal ends were connected, forming a complete channel between the two pores. The pusules
are filled with a pale pinkish fluid. The cytoplasm is exceedingly clear and transparent, with
no granular structure discernible. It usually contains from one to several food masses of
ochraceous or greenish color. In the anterodextral part of the body is a large reniform, greenish
or oil-yellow vacuolated body which seems to be a food mass. Every individual observed there-
after, however, contained this same body in about the same location. Its length is 0.80 to 0.85
transdiameter and its diameter about half its length. Its periphery is wholly covered with
small, highly refractive spherules resembling oil drops of uniform size, arranged with consid-
erable regularity. Its center contains an elongated pinkish vacuole, and in one instance what
appears to be a nucleus of the dinoflagellate type is indicative of cannibalistic tendencies. No
striations or other markings could be detected on its surface. The color is a pale glaucous blue.
In the peripheral zone were a number of greenish spherules, probably oil droplets, and in one
individual there was a peripheral zone of short radial rhabdosomes, faintly tinged with orange
or yellow near the apices in some individuals.

Dimenstons.—Length, 50-75; transdiameter, 36-63; diameter of nucleus,
17z, or with a major and minor axes of 19-30” and 15-19» respectively.

OccurRENCE.—The first individual was taken July 9, 1917, with a No. 25
silk net, 4 miles off La Jolla, California, in a haul from 80 meters to the surface,
in a surface temperature of 19°8 C. On July 11 a second individual was taken
under similar conditions in a surface temperature of 20°2 C. On July 20 it
was again taken in a haul made 6 miles offshore, in a similar haul in a surface
temperature of 21° C. A fourth individual was taken on August 10 in a haul
from 50 meters to the surface, one mile offshore, in a surface temperature of
22°5 C.

Activities.—W hen first placed under the cover glass this species is exceed-
ingly active, incessantly on the move, circling mainly in close clockwise spirals
only several lengths of the body in diameter. In about thirty to seventy minutes
it slows down, rounds up, and undergoes cytolysis. It is prone to fasten itself
to the slide by the anterior end, presumably the region of the anterior junction
of the girdle and suleus. It often circles for a long time without rotation of
the body on its axis.

CoMPARISsONS.—This species belongs to the C. distortum series in the sub-
genus Glyphodinium, and lies midway between C. rosaceum (fig. HH, 4) and
C. convolutum (fig. HH, 5). Its ventral excavation is much less than in C.
cavatum (fig. HH, 10), its torsion is greater and its displacement of girdle less,

386 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

9.59-9.62 as compared with 0.64. Its proportions are much stouter, its length
being 1.4 transdiameters as compared with 2.25. It differs from C. conspiratum
(fig. GG, 10) in being nearly twice as long, having 0.50-0.62 instead of 0.9
turn in the torsion of the suleus, and in possessing a longitudinal instead of a
transverse antapical loop.

The nature of the large vacuolated structure interpreted by us a food mass
is problematical. In the number and regularity of the vacuoles it is unlike
other food masses. There is, however, no such regularity in these structures
as appears in the nuclei of Amoebophrya parasitic in Sticholonche (see Bor-
gert, 1897), and there is no motion in the structure such as we have observed
in this parasite in Pouchetia. The interpretation of the structure as a parasite
thus appears to be excluded. The presence of the mass inside of a vacuole, and
the concentration of vacuoles about it, suggest a food mass in a rapid phase of
intracellular digestion. In case this is the correct interpretation, the similarity
of the mass in size, location, and condition in all of the individuals can be
explained only on the basis of the capture of the same type of food at about
the same interval prior to observation on the part of all of the four individuals
observed. This is a sufficient number of instances to suggest selective feeding
on the part of the organism. The nature of the food could not be determined.
Its shape and size do not agree with any known dinoflagellate. The presence
of a nucleus recognizably of the dinoflagellate type in one instance indicates that
the food may be one of the many small and as yet undescribed dinoflagellates
which occur in the plankton.

Cochlodinium virescens sp. nov.
Plate 9, figure 104; text figure HH, 11

DracNosis.—A medium sized species with ellipsoidal, nearly symmetrical,
deeply constricted body; its length 1.5 transdiameters; girdle a descending left
spiral, displaced 0.8 transdiameter; sulcus with torsion of 0.9 turn; color, yel-
lowish green. Length, 54. Pacific off La Jolla, California, July, August.

Descrierion.—The body is ellipsoidal in outline with broad, rounded apices, nearly circular
in cross-section, its length 1.5 transdiameters at the widest part at the middle. When first
confined under the cover glass the body is generally deeply constricted by the sulcus and girdle,
but still subsymmetrical, rounding out after being kept for some time under the microscope.
The epicone and hypocone are subequal in size. The epicone is subhemispherical in shape,
sometimes slightly flattened at the apex or notched at the left side by the anterior end of the
suleus. Its length from the proximal and distal ends of the girdle is 0.2 and 0.74 respectively
of the total length of the body. Its distal portion forms a wide band which makes about 0.9
turn around the body. The hypocone is subhemispherical in shape with broadly rounded or
more or less deeply notched antapex.

The girdle is a descending left spiral with a distance from the apex at its proximal and
distal ends of 0.2 and 0.74 respectively of the total length of the body, and its displacement is
0.8 transdiameter. The major part of its posterior descent takes place in the middle third of

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 387

its course, its course proximally and distally having a nearly transverse direction. The furrow
has a width of about 0.05 transdiameter, but is obscured throughout most of its course by the
rotundity of its borders. It is deeply impressed, often constricting the body to about 0.63
transdiameter, and, with the sulcus, throwing the right and left sides of the body into four
nearly alternating rounded lobes.

The suleus usually invades the epicone in an apical loop that may fade out before reaching
the apex or may notch the left side below the apex. After passing the proximal end of the
girdle it turns to the left in a descending spiral of about 0.9 turn, meeting the girdle distally
about 0.24 of the total length of the body from the antapex. Beyond the distal junction it
turns slightly towards the right, broadening and often notching the right side of the antapex.
The anterior flagellar pore opens at the proximal junction of the girdle and suleus, and the
posterior pore somewhat below the distal one.

The nucleus is a large, spheroidal body filled with coarse, moniliform chromatin strands.
It is located somewhat posterior to the midplane of the body, on the left side. Its axis is about
0.44 transdiameter in length.

In all the individuals of this species observed the pusules were united at their extremities,
forming a long tubular canal between the two flagellar pores. The cytoplasm is clear and
transparent, often with no trace of granulation. Food bodies are usually present as well as
oil globules, refractive bodies and minute blue-green granules scattered through the peripheral
zone. The color of the organism is a mixture of pearl grey and green, with a trace of orange
peripherally, varying to light turtle green throughout.

Drvensions.—Length, 52; transdiameter, 36-454; axis of nucleus, 15-24.

OccuRRENCE.—The first specimen observed was taken July 11, 1917, with a
No. 25 net, 4 miles off La Jolla, California, in a haul from 80 meters to the
surface in a surface temperature of 19°7 C. It was later observed in most
of the hauls made from August 3 to 20, 0.75 to 6.5 miles offshore, from 60 to 80
meters depth and in surface temperatures varving from 19°7 C to 22°4 C,

ComMPARIsons.—This species is distinct in the genus Cochlodinium in the
amount of constriction of the body by the girdle and suleus, the constriction
occurring throughout the entire length of both furrows, with the greatest de-
pression along the sulcus. The latter feature is common in the species of the
subgenus Glyphodinium, without, however, showing a corresponding constric-
tion of the girdle.

Cochlodinium virescens belongs in the C. citron group of the subgenus
Cochlodinium, and lies midway between C. lebourae (fig. HH, 7) and (C. radi-
atum (fig. GG, 12).

Cochlodinium volutum sp. nov.
Plate 10, figure 108; text figure GG, 1

DraGcnosis.—A medium sized species with obovoidal body, its length 1.46
transdiameters; girdle a descending left spiral of 1.5 turns, displaced 0.82 trans-
diameter: sulcus with torsion of 0.5 turn; surface coarsely striate; color, yellow
green. Length, 60. Pacific off La Jolla, California, August.

Description.—The body is obovoidal in shape, nearly circular in cross-section, broadly
rounded anteriorly and contracting posteriorly, its length 1.46 transdiameters at the widest

388 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

part in the anterior part of the hypocone. The dorsal surface is more convex than the ventral,
thus placing both apices slightly ventrad of the median frontal plane of the body. The hypocone
exceeds the epicone in size. The epicone is broadly rounded, less than a hemisphere, with a
length from the proximal and distal ends of the girdle of 0.19 and 0.82 respectively of the total
length of the body. On the dorsal and right sides of the body the basal portion forms a flaring
border to the girdle, with less prominence elsewhere. The hypocone is conical in shape, with
an angle of about 45°. It is narrower distally than the epicone with rounded antapex. <An-
teriorly it forms a shelflike border to the girdle.

The proximal and distal ends of the girdle join the suleus at a distance from the apex of
0.19 and 0.82 respectively of the total length of the body. It sweeps around the body in a
descending left spiral of 1.5 turns with a displacement of 0.82 transdiameter. The first trans-
diameter of its course is nearly transverse beyond which it turns posteriorly at a gradually
steepening angle which becomes about 35° for the last 0.5 of its course. The furrow has a
width of about 0.08 transdiameter, shghtly narrower anteriorly, and is deeply impressed with
borders raised somewhat above the surrounding surface.

The suleus invades the epicone to within a short distance of the apex. After passing the
proximal end of the girdle it is deflected to the left, and continues posteriorly in a spiral course
to near the antapex, its torsion about 0.5 turn. It is rather shallow with smooth borders. The
anterior and posterior flagellar pores open at the anterior and posterior junctions respectively
of the girdle and suleus. ;

The nucleus is a large ellipsoidal body, filled with fine, parallel, moniliform chromatin strands
which follow its long axis. It is located in the anterocentral part of the body. Its major and
minor axes are 0.46 and 0.31 transdiameter respectively.

The cytoplasm is very clear and transparent, and contains numerous blue-green oil globules
of varying sizes. A small, club-shaped pusule opens into the posterior flagellar pore, a larger,
sacklike one with a long, slender, curved diverticulum extending dorsad, opening into the
anterior pore. The surface is striate with longitudinal blue-green lines extending from the
girdle to the apices. The number of lines on the epicone exceeds the number on the hypocone
by about 0.2. The general color of the organism is yellowish green diffused throughout the
cytoplasm.

Diuensions.—Length, 60; transdiameter, 41“; axes of nucleus, 19# and 13+.

OccURRENCE.—T'wo individuals were taken August 10, 1917, with a No. 25
silk net, 1 mile off La Jolla, California, in a haul 50 meters to the surface, in
a surface temperature of about 21° C.

Comparisons.—In the type of spiral the girdle of C. volutum resembles
somewhat that of C. conspiratum (fig. GG, 10), being slightly more regular in
its course. In shape of body and apices it is close to C. scintillans sp. nov. (fig.
GG, 11), but has striae on its surface. It belongs to the C. miniatum group of
the subgenus Cochlodinium, and shares with C. miniatum the distinction of a
Gyrodinium type of striate surface.

¢

CHAPTER XV

GYMNODINIIDAE: TORODINIUM °

TORODINIUM ven. nov.
Text figure IT
Gymnodimum, Pouchet (1885a), in part, p. 67, pl. 4, fig. 29.
Gymnodinium, Lemmermann (1899), in part, p. 358.
Gymnodinium, Schiitt (1895), in part, pl. 165, pl. 238, fig. 74,_,,.
Gymnodinium, Paulsen (1908), in part, pp. 97, 98, fig. 132.

DIAGNOSIS

Body elongate, epicone several times the length of the hypocone in length,
girdle and hypoecone forming an augur-shaped cone at the antapex; girdle
forms a descending left spiral of slight displacement; sulcus with very long
apical loop with torsion of about 0.5 turn posteriorly and straight antero-
longitudinally, running most of the length of the body nearly to the apex;
nucleus faint, greatly elongated; rhabdosomes linear, sinistral, longitudinal;
marine, eupelagic. Two species; the type, Torodinium teredo (Pouchet), was
described by Pouchet (1885a, p. 67, pl. 4, fig. 29) as Gymnodinium teredo.

DESCRIPTION
The marked torsion of the sulcus, amounting to 0.5 turn, equivalent to
that in the simplest species of Cochlodinium and without parallel elsewhere
in Gymnodinium, serves to exclude Gym-
nodinium teredo from the genus in which — sale-- --
Pouchet (1885a@) deseribed it, and in
which all subsequent investigators have
left it. In all species of Cochlodinium,
as well as of Gymnodinium (except in G.
glaucum Lebour), the anterior flagellar
pore is at least premedian and never
pushed back almost to the antapex, as in
T. teredo (fig. Il). In correlation with
this posterior dislocation of this pore and
the accompanying girdle in Torodinium, CMpin es
the sulcus stretches anteriorly almost to 2
Aue E é Fig. II. Torodinium gen. nov. 1. Torodiniuwm
the apex, retaining 0.5 turn or more of the ;obustum sp. nov. Left lateral view. 2. Ventral
characteristic torsion of the apical loop, Ee Nera arate beet ES pen Roe
but exhibiting little or no torsion in its teredo (Pouchet). After Schiitt (1896, pl. 23, fig.
very much foreshortened intercingular 7, fanaa Hoa pera Se
and antapical portions. This unique ar- % nucleus; pus., pusule; rod., rodlets or rhabdo-

somes; sulc., suleus; tr. fl., transverse flagellum.

rangement of these fundamental organs, x 500.

pose

ts fhe bes
long. fl...__]~*

[389]

390 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

girdle and sulcus, compels the establishment of a separate genus to include this
aberrant species. The first step in this divergence is to be found in the aber-
rant Gymnodinium glaucum, which forms a connecting link between the two
genera.

The nucleus is conformable to the body in proportions and shape, being, in
T. teredo (fig. II, 4), eight times as long as it is wide. It is exceptionally trans-
parent and difficult to detect because of the delicacy of its membrane and trans-
pareney of the exceptionally coarse and ropelike, longitudinal, spirally twisted
chromatin threads.

The marked asymmetry of the body is exhibited not only in the asymmet-
rical contour of the short hypocone but also in the grouping of the rhabdosomes
which are linear in form and massed entirely on the left side of the body in
four parallel rows and in a star near the apex. It is possible that these struc-
tures, which we designate as rhabdosomes, are in reality chromatophores.

COMPARISONS

The structure of this genus is so unique and so far removed from other
genera that its relations are in no case immediate. It is clear, however, that
in the torsion of the sulcus it is nearer to Cochlodinium than to Gymnodinium.
In its posterior location of the girdle it is unique and at the opposite extreme
from Erythropsis, in which the girdle is far anterior with a compensating re-
duction of the epicone. The extreme reduction of the hypocone in Torodinium
is without parallel among free-living Gymnodinioidae, except as foreshadowed
in Gymnodinium glaucum.

It is also worthy of note that the cytoplasmic differentiations of pigmented
rhabdosomes (or chromatophores?) are sinistral as is the ocellus of Erythropsis,
but they are in the epicone instead of the hypocone as in the latter genus.

Historical DiIscusslon

The first species now included in this genus was described by Pouchet
(1885a) as Gymnodinium teredo, Schutt (1895) found both species, but did
not differentiate them, referring them both to G. teredo. We have found only
the stouter of these two species, Torodinium robustum, in which we include the
first two of Schiitt’s figures (1895, pl. 23, figs. 74:.) of G. teredo, referring the
remainder to the species to which he assigned them.

Kry To Spectres oF Torodinium

Length less than 3.5 greatest transdiameters, suleus with reversed terminal apical loop —............
sesolive sic epuenneususied ues ste letee Soseccentesasescezesoneerses stekieecrse =k sae ae nea ee ee ee robustum sp. noy.

Length more than 4 transdiameters, no loop in terminal part of the suleus ...... teredo (Pouchet)

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 391

Torodinium robustum sp. nov.
Plate 4, figure 49; text figure II, 1-8

Gymnodinium teredo, Schiitt (1895), in part, pl. 23, figs. 74,.,. Figs. 74,.,, are 7. teredo
(Pouchet).

DraGnosis.—Medium sized species, elongated, fusiform, its length 2.8 to 3.2
transdiameters; epicone 0.83 to 0.85 total length; hypocone minute, conical,
asymmetrical; girdle a descending left spiral, displaced slightly; suleus with
torsion of 0.4 turn proximally and 0.75 reversed turn in apical region. Length,
67- to 75". Atlantic or Bay of Naples; Pacific off La Jolla, California, July.

Description.—The body is elongate fusiform, with little taper, slightly fuller anteriorly,
widest at the middle, its length 2.8—3.2 transdiameters measured at the widest part near the
middle. The epicone greatly exceeds the hypocone, its length at the proximal end of the girdle
0.83-0.88 total length, while at the distal end it almost reaches the antapex, apex broadly
rounded ; hypocone reduced to a minute asymmetrical cone which with the girdle above it takes
on the form of the tip of an augur (fig. II, 1-8, hyp.). Its length at the proximal end of the
girdle is 0.12 to 0.15 of the total length, and its diameter 0.3 to 0.4 transdiameter. It is quite
asymmetrical with its antapex towards the right (of the body) of the major axis when viewed
ventrally, that is, with the anterior pore midventral. Its ventral slope is about twice as long as
the dorsal. It forms a lopsided cone of 70°—90°, according to the view or degree of contraction
and its antapex is pointed.

The girdle is a descending left spiral slackening distally, displaced about twice the width
of its furrow, its distal end merging directly with the distal end of the suleus (fig. II, 1-3, gir.).
The furrow is deeply impressed with prominent, overhanging lips. The diameter of the body
in the oblique girdle is only about 0.35 transdiameter. The suleus runs almost from apex to
antapex. Assuming for purposes of description that the location of the anterior flagellar pore
establishes the planes of orientation of the body as a whole we may define the course of the
suleus as follows. It begins very near the anterior end with a reversed loop of nearly 0.75 turn,
that is, running from the left side of the body around ventrally to its right instead of the usual
spiral course seen in the torsion of the suleus. This loop is deflected posteriorly 10°-15° below
the horizontal, increasing posteriorly to within less than a transdiameter of the anterior end,
where it has turned to a posterior direction, which it then pursues longitudinally a little to the
right of the middorsal line. At 0.5 transdiameter from the antapex it turns in the customary
descending left spiral for 0.4 turn at 25° below the horizontal to its junction with the girdle.
Its course below this point is a short expanded area on the ventral face of the button-lke
hypocone. The transverse flagellum encireles the body and the stout posterior flagellum is one
transdiameter in length. Both arise close together near the proximal end of the girdle.

The nucleus is an elongated rod with rounded ends, 0.5 of the length of the body in length
and slightly wider posteriorly. Its length is six times its middiameter. It is traversed by about
ten coarse, moniliform chromatin threads which form a steep spiral about its main axis. The
nuclear membrane is very faint and the nucleus remarkably difficult to discern in life. From
the anterior flagellar pore there runs anteriorly at the left of the nucleus a slender canal, the
anterior pusule. No posterior pusule was found. On the left side of the body are four con-

” or rhabdosomes, which were a pale oural green in

tinuous linear peripheral ‘‘chromatophores’
our specimens. Schiitt (1895) figures them as of the same pale ochre as those of his other
figures of G. teredo. They are 0.65 of the total length of the body in length, equidistant and
somewhat unequal in length. Grouped about a central oil globule in the sinistroventral part

of the apical region is a partial chromatophore (?) star of eight or nine rays grouped mainly

392 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

on the anterior are of a complete circle. Scattered through the cytoplasm are numerous highly
refractive spherules filled with a glaucous green fluid. Schiitt (1895) figures a layer of per-
ipheral radial rhabosomes in regions where there are no chromatophores (?). There is no
evidence that this organism is holozoie, neither is the color of the ‘‘chromatophores’’ or rhab-
dosomes conclusive of holophytie nutrition.

There are no striae on the surface. The general color of the plasma is a pale veronese green.
Rhabdosomes or chromatophores and nucleus alike round up, as cytolysis approaches, and the
body itself also foreshortens and rounds up till its transdiameter is half its length.

DiMenstons.—Length, 65-75 (83); transdiameter at widest part, 21-23
25)»; dorsoventral diameter in oblique girdle, 6-8 (8); axes of nucleus, 5
and 32”. Dimensions of Schiitt’s figures (1895, pl. 23, figs. 74:.) are given in
parentheses.

OcCURRENCE.—This species was recorded in the plankton taken 4 to 11 miles
off La Jolla, California, in July and August, 1917, in hauls taken from depth
of 80 to 20 meters to the surface in surface temperatures of 18°8 C to 22°5 C.
It was not recorded in all the catches, but in considerably more than half of
them. As high as fifteen individuals were noted in one collection. It was never
noted in the plankton taken daily at four-hour intervals off the pier at the
Biological Station.

It was also recorded July 3, 1906, in a haul 2.75 miles off La Jolla from
155 meters to the surface in a surface temperature of 20°4 C.

Schiitt (1895) figures it presumably from the Bay of Naples or from the
collections of the Plankton Expedition in the Atlantic. The records of Gymno-
dinium teredo made by Schroder (1900) at Naples may exclude this species
since he cites only Pouchet’s (1885a) figure, which is Torodinium teredo. On
the other hand Lebour (1917)) notes a ‘‘variety of shapes’’ in the material of
G. teredo at Plymouth. This suggests the occurrence of this species in her
material.

Activitres.—This is an exceeding active organism, darting about in long
trajectories with little curvature. Its incessant rotation makes observation
difficult. When quiescent it usually hes with the left side uppermost and is
not easily dislodged, suggesting some adhesive function of the suleus which on
the applied face may be locally active in taking hold on the substrate. The
antapical region is particularly difficult to interpret owing in part it seems to
some mobility of the borders of the girdle and sulcus.

Comrparisons.—This species differs from 7. teredo in its stouter body and
shorter main axis, 75 as against 110+. The main distinction, however, appears
to he in its possession of a reversed terminal anterior loop of 0.75 turn of the
sulcus. This is wholly lacking in 7. teredo (fig. II, 4). The turn of the sulcus
immediately above the girdle is a trifle shorter (0.4) in 7. robustum than in
T. teredo (0.5). The more greenish tone noted in the plasma in our specimens
and in the so-called chromatophores as compared with the ochraceous tones of
Schutt’s (1895) may be wholly a metabolic phenomenon and not a specific dis-
tinction. Our observations lead us to the conclusion that 7. robustum and T.
teredo are not phases due to contraction or metabolism of the same species.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 393

Torodinium teredo (Pouchet)
Text figure IT, 4

Gymnodinium teredo Pouchet (1885a), pp. 67, 82, 88, pl. 4, fig. 29.

G. teredo, Schiitt (1895), in part, pp. 5, 6, 65, 71, 109, 115, 117, pl. 23, figs. 74,_,,. Figs.
74, are Torodinium robustum nom. sp. nov.

G. teredo, Lemmermann (1899), p. 358.

G. teredo, Schroder (1900), p. 13.

G, teredo, Karsten (1907), p. 307.

G. teredo, Paulsen (1908), in part, pp. 97-98, fig. 132.

G. teredo, Lebour (1917b), in part (?), pp. 188, 197.

DraGnosis.— Medium sized species, body elongate, subfusiform, length 4.3—5
transdiameters; epicone forms 0.88-0.91 total length; girdle forms proximally
a descending left spiral, without overlap, displaced less than 1.5 furrow’s width;
sulcus with torsion of 0.5 turn adjacent to the girdle, no loop at apex. Length,
100-1134. Atlantic, Pacific, and Indian oceans, Plymouth Sound, Mediter-
ranean.

DescripTion.—The body is elongate asymmetrically subfusiform, left side (of suleus) more
convex, widest near the middle, length 4.3-5 transdiameters measured at the widest part: epicone
very greatly exceeds the hypocone, forming 0.88-0.91 total length of the body; the hypocone is
subconieal with an angle of 50°, with its axis ventral to the main axis and the dorsal slope nearly
twice the length of the ventral, with pointed antapex. In combination with the girdle it forms
a single turn of a descending left spiral, with a total displacement dorsally of about 1.5 widths
of the furrow. The proximal 0.5 turn on the left side descends 20° from the horizontal to the
middorsal line, but ascends again in the distal part with the result that the ventral face of the
hypocone is longer than the dorsal (fig. II, 4). There is no overlap. The furrow has an over-
hanging anterior lip and is deeply impressed. Its width is about 0.12 transdiameter at the
widest part of the body.

The sulcus originates anteriorly within a short distance of the apex, runs longitudinally
posteriorly to within 1 transdiameter of the antapex, turns in a descending left spiral for 0.5
turn at about 45° to its junction with the girdle on the opposite side. It is not distinguishable
beyond this point. It has no reversed loop in the anterior end of the body. The flagellar pore
lies near the junction of girdle and sulcus.

The nucleus is elongated cylindrical with rounded ends. Its major and minor axes are
respectively 3 and 0.45 transdiameters in length. It is traversed diagonally by 8-10 vaguely
outlined spiral chromatin strands and its boundaries are indistinct. A longitudinal pusule,
opening posteriorly at the flagellar pore, runs anteriorly nearly to the apex. It may be broken
up into a line of separated vacuoles (Schiitt, 1895). Refractive fatty spherules of varying sizes
are clustered near the apex and along the right side and an axial plastid containing what Schiitt
(1895) has ealled B-oil may be located in the anterior half of the epicone. Ochraceous chromato-
phores or rhabdosomes arranged in four longitudinal rows of rods from 0.5 to 1 transdiameter
in length and about 0.1 in diameter are found on the left side for the middle 0.7 of the total
length of the body. Several additional stouter chromatophores or rhabdosomes as radii are
found above the four rows near the apex. They are clustered about a central oil spherule.

The plasma is almost colorless and shows no peripheral striae.

Dimensions.—Length, 100-113; transdiameter at widest part of the body,
23-264; axes of nucleus, 75” and 10.

394 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

OcCcURRENCE.—Oceasional in the plankton taken off La Jolla, California,
in July and August, 1917, in hauls from 80 meters to the surface in surface
temperature of 19° C to 21°5 C. Reported by Pouchet (1885a) from the
Atlantie at Conecarneau and by Miss Lebour (1917b) from Plymouth Sound,
England, where it was abundant in July and August, and rarely even into the
winter months, during which it was the only representative of the Gymnodi-
nioidae found. The extreme variability noted by Miss Lebour may be due to
the inclusion of 7. robustum in this species. Schroder (1900) found it in July
and August in the plankton of the Bay of Naples; and Karsten (1907) records
it in one haul of the Valdivia Expedition, made from 100 meters to the surface
near the center of the Indian Ocean in March. It thus appears to be a eupelagic
species, probably of wide distribution in tropical and warm temperate seas.

ComMParRIsONS.—This is the slenderest species not only of Torodinium but
likewise of all of the free-living Gymnodinioidae. The shortening of the trans-
verse flagellum and of the girdle in which it lies has extended to such a degree
that the transdiameter of the body in this region is little more than 0.35 of that
of the widest part of the body, a region in which the girdle is normally located
in most Gymnodinioidae.

SynonyMy.—This species was described as Gymnodinium teredo by Pouchet
(1885), and has been retained in that genus by all subsequent investigators
who have dealt with it. Schiitt (1895) did not separate it from T. robustum,
which he includes in his figures of 7. teredo. This confusion appears to have
been continued by Lebour (1917)), and possibly others.

CHAPTER XVI

POLYKRIKIDAE: POLYKRIKOS
Family 3. POLYKRIKIDAE fam. nov.

DrAGNosis.—Gymnodinioidae with a permanent colonial organization, 2, 4,
or 8 zooids in chain, each zooid having a Gymnodinium type of structure; girdle
a descending left spiral of one turn; sulcus extending from apex to antapex;
ocellus and tentacle lacking; plasma colored without pigment; nematocysts
present. Marine, eupelagic and neritic, and from warm temperate waters. One
genus.

POLYKRIKOS Biitschli

Text figure F

Polykrikos Bitschli (1873), pp. 673-676, pl. 26, fig. 22; (1885), pp. 1011, 1012, pl. 55
fig. 8.

Polykrikos, Saville-Kent (1880-82), PP. 858, 860.
Polykrikos, Bergh (1881b), pp. 255-259, pl. 16, fig. 72.
Polykrikos, Delage and Hérouard (1896), p. 386, fig. 679.
Polykrikos, Calkins (1901), p. 140.
Polykrikos, Lang (1901), p. 23.
Polykrikos, Hartog (1906), pp. 110, 131, 132.
Polykrikos, Kofoid (19076), pp. 291-298, fig. 1.
Polykrikos, Paulsen (1908), pp. 106, 107, fig. 149.
Polykrikos, Poche (1913), p. 162.
Polykrikos, Chatton (1914c), pp. 157-194, figs. 1-13; pl. 9, figs. 1-14.
Polykrikos, West (1916), pp. 54, 79, fig. 39.

DIAGNOSIS

Polykrikidae of 2, 4, or 8 zooids in chain, each zooid with a Gymnodinium
type of structure, girdle a descending left spiral of 1 turn; suleus extending
the whole length of the body and continuous with that of the adjacent zooids,
each zooid having the same orientation. Number of nuclei is usually less than
that of the zooids, generally in a ratio of 1 to 2. Nematocysts present; surface
of lypocone ribbed or smooth; holozoie nutrition. Plasma colored, without
pigment. Length of chain of 4 zooids, 2154. Marine, eupelagic and neritic,
and from warm temperate waters. Two species.

ORGANOLOGY

The individual zooids of Polykrikos differ but little from many species of
the genus Gymnodinium, their colonial habit and the presence of nematocysts
alone separating them from that genus. The body of the colony as a whole is

[395]

396 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

elongate barrel-shaped, the extreme length reached in the eight-zooid stage being
4-5 transdiameters at the widest part near the middle. The girdle is usually
transverse with its posterior displacement occurring at its distal extremity.

The body is without appreciable torsion, each zooid having the same orien-
tation as its neighbor, with their sulci connected at their extremities and forming
a continuous channel along the ventral face of the colony. The sulcus usually
terminates near the right side of the apex of the proximal zooid and at the
antapex of the distal one.

The nucleus of Polykrikos has the beaded chromatin strands characteristic
of the Dinoflagellata generally and is without a distinct perinuclear zone. The
number of nuclei in the colony is usually half the number of zooids.

The color of the cytoplasm of Polykrikos varies from a greenish tint, or
almost colorless, to faint, diffuse rose, and is probably subject to considerable
modifications through the food ingested by the organism. It is not improbable
that the rosy tint results from feeding upon rose or red colored forms, like
Peridinium divergens and P. conicum, usually abundant in the plankton with it.
Noctiluca scintillans, feeding on the same plankton, exhibits a similar varying
rosy tint in its color. The presence or absence of this color is one of the char-
acters which Bergh (18810) uses in separating his Polykrikos auricularia
from Biitschli’s species (1873), P. schwartzi, a distinction which is apparently
not well grounded.

Polykrikos is holozoie in nutrition, as the abundance of individuals found
with recognizable organisms in the cytoplasm indicates. These may include
almost all the small organisms occurring in the plankton with it, both metazoan
and protozoan.

The nematocysts of Polykrikos are found in all individuals without ex-
ception. They vary considerably in number and arrangement and have been
observed to shift their position during the spasmodic plasmatic movements
sometimes seen in the interior of the organism, and are often crowded to per-
ipheral locations by the relatively large food masses sometimes ingested. They
are not, when developed, fixed organs with definite locations, but may occur in
any part of the body. Chatton (1914e) has demonstrated their origin from the
serially arranged centrosomes at the right of the nuclei.

Division in Polykrikos is accomplished by the formation of new girdles
between the already existing ones, followed by a division of the nuclei. <A
division of the colony is accomplished by a constriction of the body along the
line of separation of the middle zooids, and may occur in four, eight, or sixteen
zooid stages.

DISTRIBUTION
Polykrikos oceurs along the western coast of Europe, as far north as Nor-
way, in the Mediterranean, and along the coast of California, giving it a known
distribution that is exceeded in its breadth by only a few species among the
Gymnodinioidae. Its occurrence is thus confined largely to warm temperate

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 397

waters, or to the more northerly waters which receive warm currents, yet the
significance of this fact is greatly modified by its seasonal distribution. Its
occurrence in its more northerly range is quite as frequent in the colder as in
the warmer months. Thus it has been found in the North Sea and the Skage-
rack from September to January (Aurivillius, 1896-98) and along the coast of
Norway in November and December (Jorgensen, 1899).

Polykrikos, unlike most of the Gymnodiniidae, is fairly well able to with-
stand the destructive influences of fixing fluids, and is occasionally found in
preserved material. In examinations of the plankton hauls made off San Diego
for several years and covering every month of the year specimens of Polykrikos
have been found only in the hauls made during June and July of different
years. Inthe summer of 1917 it was present from June 26 to August 22, though
never abundant. It has been found in San Francisco Bay in October and
' November.

HistoricaL Discussion

The history of Polykrikos has been a varied one, owing to its peculiar
structure, which, in the earlier descriptions of it, was but imperfectly under-
stood and served to obscure its relationships. The organism was first described
by Ouljanin (1868) as a pelagic turbellarian larva and later by Biitschli (1875
as a ciliate infusorian, Polykrikos schwartz. In 1881b Bergh referred it to
the Cilioflagellata, added another species, P. auricularia, and figured cilia on
the transverse furrows. Later Pouchet (1883, 1887) accepted this allocation,
without. however, figuring the cilia. Bitschli (1885) in his monograph on the
Dinoflagellata recognized the dinoflagellate character of this organism and
omitted the cilia in his figures, substituting flagella therefor. He placed it in
a separate family, Polydinidae. Schiitt, both in his systematic monograph of
the Peridiniales (1896) and in his report on the Peridiniales of the Plankton
Expedition (1895), omitted all reference to the genus.

Delage and Hérouard (1896) marked it off as a still more unusual form by
creating for it the order Polydinida with this genus as its sole representative.
Kofoid’s (1907b) work on this puzzling organism served to clear up many of
the obscure points in its structure with a resulting clearer elucidation of its
relationships. He placed it in the family Gymnodinidae (= Gymnodiniidae )
without further isolation unless that family should be broken up into subfam-
ilies. A critical examination of an abundance of material also indicated that
both Biitschli and Bergh were dealing with one and the same organism and
not with two distinct species. Our later work on Polykrikos confirms these
earlier observations (Kofoid, 1907b), and we therefore place Bergh’s species
as a synonym of Biitschli’s P. schwartz.

The form figured by Kofoid was afterward separated from P. schwartzi
by Chatton (1914¢), as P. kofoidi. The specific distinctions on which he based
this separation are two in number, the first being the absence of nematocysts,

398 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

and the second the presence of distinct longitudinal striae, or furrows, on the
hypocone of each zooid. The first distinction is not a valid one, since the
nematocysts were intentionally omitted from the original drawing with most
other internal structures. Each individual of this genus found in the waters
of the San Diego region is provided with these distinctive organelles. The
second distinction, namely, the surface markings on the hypocone (fig. F, 1),
clearly marks this species off from P. schwartzi, which is also present in the
waters of San Diego. In other respects these two species appear to be nearly
identical, and the final critical discussion of their status awaits a reinvestigation
of the Pacific species, if such it be.

Kery To Species oF Polykrikos

1. Surface of hypocone of each zooid deeply ribbed, girdle displaced one-fifth length of body ....
Ne ae pe ae ere teen Seca ent kofoidi Chatton

2. Surface of hypocone smooth, girdle without displacement — 0... schwartzi Biitschli

Polykrikos kofoidi Chatton
Plate 4, figure 47; text figure F, 1

Polykrikos schwartz, Kofoid (1907b), in part, pp. 291-298, fig. 1.
P. kofoidi Chatton (1914c), p. 161.

Dracnosts.—This is a colonial form of 2.4, 8, or 16 individuals in chain,
each individual rather small in size, its length about 0.43 transdiameter; girdle
submedian, displaced 0.15 transdiameter ; sulcus extending length of body; sur-
face of hypocone ribbed; nematocysts present; color, greenish grey to rosy.
Length of chain of 4 zooids, 110#. Pacific off La Jolla, California, June to
August.

DescriptTion.—The individual zooids are small in size, rotund, nearly cireular in cross-section,
or slightly dorsoventrally depressed with a length of about 0.43 transdiameter. The epicone
and hypocone are subequal in size with a tendeney towards a slight decrease in the relative size
of the epicone. The chain of two, four, or eight zooids presents a barrel-shaped appearance
with broadly rounded apices, somewhat constricted at the girdles and the points of separation of
the different zooids. The girdle of each zooid is submedian or slightly premedian in position.
It follows a nearly transverse direction around the body with a slight posterior deflection of
the distal end, resulting in a displacement of about 0.15 transdiameter. The furrow has a width
of about 0.03 transdiameter and is deeply impressed, the excavation having a slight anterior
extension, deeply undercutting the anterior border and gradually rounding out to the posterior
one. The anterior lip is usually smocth and the posterior one often thrown into undulations
similar to those on the surface of the hypocone.

The sulcus forms a continuous furrow on the ventral face of the chain of zooids, extending
in a slightly sinuous line from near the apex of the first zooid to the antapex of the last one.
Its width is about half that of the girdles, enlarging slightly at the points of union with the
girdles and usually at place of union of the different zooids. At the antapex of the posterior
zooid its sides become widely deflected, forming a wide, shallow notch on the ventral face. The
anterior flagellar pores open at the proximal junctions of the girdles and suleus, the posterior

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 399

pores just below the distal junctions. The transverse flagella seldom have a length greater than
0.5 turn around the body and the posterior flagella are usually about equal to the length of a
single zooid. These usually do not le in the sulcus, but are thrown out at a slight angle. The
longitudinal flagellum of the posterior zooid may be considerably longer than the other longi-
tudinal flagella.

The nucleus is a spheroidal body, filled with moniliform chromatin strands. It is generally
found near the center of the body, slightly to the right of the suleus. Its transdiameter is
about 0.39 transdiameter of the body in length. The number of nuclei usually lags behind the
number of zooids in a chain, one being present in a two-zooid chain, two in four zooids, and
four in eight zooids, showing a lack of synchronism in the division of nuclei and eytoplasm.

The plasma is translucent, finely granular and generally abundantly filled with nematocysts,
food bodies and vacuoles. The nematocysts vary in number and arrangement in different
individuals. This species is an omnivorous feeder, appropriating almost any small organism
found in the plankton, such as crustacean larvae, copepod eggs, other dinoflagellates, as
Gonyaulax, Peridinium, and Diplopsalis, with other organisms indistinguishable owing to their
advanced stage of digestion. It is evident from the large size of many of the food bodies thus
taken in that two or more individuals of the chain must codperate in the process of ingestion.
The ejection of solid particles has been observed from the suleus at the region of the posterior
pore. This takes place very quickly, the cytoplasm closing up to its normal appearance in about
thirty seconds.

The plasma has a rosy tint, varying sometimes to pale green or almost colorless. The depth
of the rose color varies greatly in different individuals, and is more pronounced in the peripheral
zone of cytoplasm. The surface of the epicone is generally smooth, that of the hypocone striate
and furrowed, about ten striae or ribs on 0.5 transdiameter. The surface between the striae
may be raised into smoothly rounded ridges.

Activities.—These are very active organisms, their incessant motion making
any attempt to determine the codrdination or lack of it, in the movements of
the different flagella, a matter of great uncertainty. When first placed under
the microscope the progression is mainly in loose, anticlockwise spirals with
only occasional clockwise rotations, varied with jerking motions of the anterior
end upward, and occasionally reversing its spiral direction. Hither the ventral
or dorsal side may be uppermost when quiescent.

Codrdination in the movements under the cover glass of the different sets
of flagella is lacking at least part of the time. One or two of the transverse
flagella may be in active motion with the others only faintly or not at all motile.
When all are moving at the same time the rate of motion is not the same for
all nor does motion begin in each at the same time. This is equally true of the
longitudinal flagella.

Under the brilliant illumination necessary for microscopic work the
organism soon rounds up to a spheroidal form, the girdles becoming completely
obliterated and motion ceasing gradually. With cytolysis and dissolution of
the body, the nematocysts are usually discharged a few seconds after the
breaking down of the body wall.

Divensions.—Length of individual zooid, 25-45; length of 4-zooid chain,
110; transdiameter, 70-90; diameter of nucleus, 25-30; length of nematocysts,
10-20+. ;

400 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

OccuRRENCE.—This was found abundantly at La Jolla, California, in hauls
made from June 27 to July 17, 1906, from near shore to 7 miles offshore and
from the surface as well as in hauls from depths up to 595 meters, in surface
temperatures varying from 20°4 C to 21°4 C. There is no evidence that it
lives in such depths. In July, 1914, and also in July and August, 1915, it was
observed in the surface hauls made near shore, though not abundant in either
year. In 1917 it was present in the majority of the hauls made between June
26 and August 22, both in the surface hauls made at the end of the pier and at
the Biological Station and in the deeper hauls made from 1 to 11 miles offshore
from depths up to 80 meters.

SynonymMy.—This was figured by Kofoid (1907) as P. schwartzi. Chatton
(1914c) separated it from that species and gave to it specific rank as P. kofoidi.

Polykrikos schwartzi Biitschli
Text figure F, 4

Turbellarian larva, Ouljanin (1868), p. 161.
Polykrikos schwartzi Biitschli (1873), pp. 673-676, pl. 26, fig. 22; (1885), pp. 964, 965,
pl. 55, figs. 8a-c.

Polykrikos swartzii, Allman (1875), pp. 176, 177, pl. 118, fig. 2.

Polycricus schwartzwi, Grimm (1878).

Polykrikos swartzii, Saville-Kent (1880-82), pp. 83, 858, 860 (P. schwartzi and P. auri-
cularia) .

. auricularia Bergh (1881a), p. 9; (1881b), pp. 256-259, pl. 16, fig. 72.

. auricularia, Entz (1882), p. 189.

. auricularia, Pouchet (1883), pp. 450-452; (1885a), pp. 66, 80; (1885), p. 530; (1887).
pp. 108-111, pl. 9, figs. 10-13; (1894), p. 170.

. auricularia, Balbiani (1884), pp. 367-370, fig. 45.

. schwartzi, Bovier-Lapierre (1886), pp. 585-536; (1888), p. 579.

. schwartzi, Mobius (1888), p. 112.

. auricularia, Schilling (1891b), pp. 200, 206.

. auricularia, Lauterborn (1893), p. 210.

. auricularia, Delage and Hérouard (1896), p. 386, fig. 679.

. schwartzi, Aurivillius (1896), pp. 22, 30; (1898), pp. 204, 282, 288, 296, 390, 392 (as
Polycricus auricularia).

. auricularia, Jorgensen (1899), tables 18, 72; as P. schwartzvi (1912), p. 10.

. auricularia, Lemmermann (1899), p. 375; (1902), p. 263.

. auricularia, Pavillard (1905), pp. 49, 80.

. auricularia, Dogiel (1906), p. 37.

Polycricos auricularia, Ostenfeld (1906), p. 19; (1909), p. 8; (1913), pp. 123, 141, 339.

Polykrikos schwartz, Paulsen (1907), p. 24; (1908), p. 107, fig. 149.

P. schwartzi, Kofoid (1907b), in part, pp. 291-298, 1 figure.

Polycricus auricularia, Lohmann (1908), pp. 252, 284, 369.

Polykrikos schwartzi, Doflein (1911), p. 528, fig. 476.

P. schwartzi, Kofoid and Rigden (1912), p. 337.

P. auricularia, Cavers (1913), pp. 182, 188, fig. 9.

P. schwartzi, Fauré-Fremiet (1913a), pp. 366-368; (1913b), pp. 289-290, fig. 1.

ne] las| Ins) as} tacplasiasl: slash as/lt as)

asi lache neha}

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 401

P. schwartzi, Chatton (1914b), pp. 434437, figs. 1-8; (1914c), pp. 157-194, figs. 1-13.
P. schwartz, West (1916), pp. 54, 55, fig. 39.
P. schwartz, Lebour (1917b), p. 198.

DraGnosis.—Colonial body composed of 2, 4, 8, or 16 zooids, each Gymno-
dinitum-like in structure, the length about 0.44 transdiameters, girdle median,
without displacement; sulcus extending length of body; surface smooth; nema-
tocvsts present; color, green to rosy. Length of chain of eight zooids, 140+.
Baltic, Mediterranean, North Sea, Atlantic, Pacific off La Jolla, California,
June-August.

DeEscripTION.—The individual zooids are small, subcireular in cross-section, with a length of
0.44 transdiameter. The colony of eight zooids has a length of about 4.21 transdiameters at the
widest part, with the body having a subeylindriecal form with broad apices. The proximal and
distal zooids are usually slightly smaller than the other zooids. The lines of separation of the
different zooids show the same constriction found in P. kofoidi. The epicone and hypocone are
subequal. The apex of the proximal zooid is broadly rounded, or may be slightly flattened.
The antapex of the distal zooid is also broadly rounded and often notehed by the distal end of
the suleus.

The girdle of each zooid is nearly submedian in position. It follows a transverse direction
around the body without displacement of its distal end. The furrow has a width of about 0.04
transdiameter and is deeply impressed with the excavation having an anterior extension, under-
cutting the anterior border and gradually rounding out to the posterior one. Its borders are
smooth.

The suleus extends from near the apex to the antapex of the colony as a continuous furrow.
Its width is irregular, becoming wider at each junction with the girdles, narrowing to half that
width in the intercingular areas. At the antapex of the distal zooid it forms a broad, shallow
notch. The anterior flagellar pores are located at the junction of girdles and sulcus, the posterior
pore shghtly posterior to those points. The transverse flagella often have a length equal to that
of the girdles. The longitudinal flagella have a length slightly greater than the length of the
single zooid.

The nucleus is a spheroidal body filled with moniliform chromatin strands. Its transdiameter
is about 0.83 transdiameter of the body. As in P. kofoidi, the number of nuclei usually equals
half the number of zooids of the colony.

The plasma is finely granular, and often contains oil globules and minute refractive granules.
The nematoeysts vary in number and are not constant in position. Food bodies of varying sizes
are common in many of the individuals noted, frequently being huge in size and displacing the
contents of the entire body. The color of the cytoplasm varies from a grey green to a rose, though
none have been found so deeply colored as those figured by Bergh (18816).

Dimensions.—Length of individual zooid, 15; length of chain of 8 zooids,
140+; transdiameter, 65; diameter of nucleus, 20/; length of nematocysts,
10-204.

OccuRRENCE.—This has been found at La Jolla, California, with P. kofoidi,
though not so abundantly, in hauls made from June 27, 1906, from near shore
to 7 miles offshore and from the surface in hauls from various depths up to
595 meters, and in surface temperatures varying from 20°4 C to 21°4 C. In
1917 it was found in a few hauls made between June 26 and August 22, both
in the surface hauls made at the end of the pier at the Biological Station and
in the deeper hauls made from 1 to 11 miles offshore from depths up to 80
meters.

402 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Earlier records of its occurrence are as follows: Ouljanin (1868) ; Biitschli
(1873) off the coast of Norway; Bergh (1881b) from the Baltic off the coast
of Denmark in July; Pouchet (1883, 1885, 1887) from the Atlantic off Con-
carneau, France, April to July, and in the Arctic near Iceland in August;
Lauterborn (1893) from the North Sea off Helgoland, Germany; Aurivillius
(1896) from the Baltic at Kiel, Germany, (1898) from the Skagerack in Jan-
uary and September to November; Jorgensen (1899) off the west coast of
Norway at Hjeltefjord in May, at Puddefjord in November and December, and
(1912) from the Skagerack in September, November, and December; Pavillard
(1905) from the Mediterranean at Etang de Thau near Cette, France, in October
and April; Ostenfeld (1906, 1909, 1913) from the North Sea, August, November,
the Skagerack and Cattegat in November; Lohmann (1908) from the Baltic at
Kiel, Germany, in April, May, and September; and Lebour (1917b) at Ply-
mouth Sound, England, from May throughout the summer. It is thus seen to
be somewhat cosmopolitan in its habitat.

Comparisons.—This species differs from P. kofoidi mainly in the lack of
ridges on the surface of the hypocone and in the lack of displacement of the
girdle. In P. kofoidi the girdle has a displacement of about 0.15 transdiameter.
The length of the latter species appears to be somewhat greater than that of
P. schwartz.

SynonyMy.—This organism was described by Biitschi (1873) as P.
schwartzi. Bergh (1881b) described a second species as P. awricularia, which
Kofoid (1907b) later reduced to a synonym of Biitschli’s species, P. schwartzi,
critical examination of the two forms failing to reveal distinct specific differ-
ences. The form figured by Kofoid was separated by Chatton (1914c) from
P. schwartzi and given specific status as P. kofoidi.

CHAPTER XVII

NOCTILUCIDAE: PAVILLARDIA, NOCTILUCA
Family 4. NOCTILUCIDAE Saville-Kent

Noctilucidae Saville-Kent (1880-82).
Noetilucidae, Poche (1918), p. 165.

DIAGNOSIS
Gymnodinioidae characterized by the presence of a tentacle, more or less
mobile, and without ocellus. The tentacle arises in the suleal area and extends
posteriorly. In Noctiluca this fundamental relationship is obscured in the
large globular form, but is apparent in the small, Gymnodiniwm-like stages.
This family contains two genera, Noctiluca Suriray and Pavillardia gen. nov.

Historicat Discussion

This family was created by Saville-Kent (1880-82) for two genera, Nocti-
luca Suriray and Leptodiscus Hertwig. The latter species is known in only
one stage of its life history. The Gymnodinium or dinoflagellate stage, if such
occurs, still remains to be discovered. This fact leaves its generic relations an
unsolved problem. Further investigation will be required before it can be more
definitely located. We therefore remove it from the family Noctilucidae and
place it, with Craspedotella Kofoid, in the family Leptodiscidae Kofoid, in the
Cystoflagellata Haeckel.

Because of its definite dinoflagellate characters of suleus and girdle and of
the Gymnodinium-like stage in its life history Noctiluca is closely allied to the
Gymnodinioidae. We therefore place it in that tribe, removing it from the
Cystoflagellata Haeckel, a group whose genetic relationships as shown in the
Leptodiscidae are still obscure.

Key To GENERA OF Noctilucidae

Gymnodimum-like girdle and suleus persistent, reddish orange pigment present...
etd ee ee ee Aarne OTA Md 2c AC AES te BN are Aes sh Pavillardia gen. nov.
Gymnodinium-stage temporary, tentacle retained in huge globular stage —... Noctiluca Suriray

PAVILLARDIA gen. nov.
Text figure JJ

DiaGnosis.—Gymnodinioidae with Gymnodinium-like girdle
and sulcus; longitudinal flagellum usually absent: stout, finger- x
like, mobile tentacle directed posteriorly; no ocellus. Type | Fig. JJ. Pavil-

lardia tentaculifera

species Pavillardia tentaculifera sp. nov. apie ynSeibO0!

[403]

404 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

HistoricaL Discussion

The possession of a stout mobile tentacle affords an adequate justification
for generic distinction of organisms from those without this characteristic.
Indeed, the possession of this organ in Noctiluca was one of the prime grounds
for the establishment of the order Cystoflagellata. The genus differs from
Protodinifer im the presence of a complete girdle not posteriorly located, but
resembles it strikingly in the shape, location, and behavior of the tentacle. It
differs from Hrythropsis in having a girdle of the slightly displaced Gyro-
dinium type and in the entire absence of the eyespot, although the presence of
the brilliant brown pigment in the tentacle is suggestive of the pigmentation
in that genus. It differs from Noctiluca in the completeness of the girdle and
in having the typical form of the Gymnodiniidae instead of that of the inflated,
subspherical body of Noctiluca.

The genus is named in honor of Professor J. Pavillard, the botanist of
Montpellier, whose researches at the Station Biologique at Cette, France, have
added much to our critical knowledge of the Dinoflagellata.

Pavillardia tentaculifera sp. nov.
Plate 10, figure 114; text figure JJ

DraGnosts.—A medium sized species with stout ovate body, its length 1.75
transdiameters; girdle shghtly premedian, displaced 0.33 transdiameter : sulcus
extending from near apex to antapex; surface faintly striate; stout club-shaped
tentacle directed posteriorly from antapex; color, pale yellow. Length, 58.
Pacific off La Jolla, California, July.

Descrirti0on.—The body is stout ovate, widest posteriorly ; circular in cross-section, its length
1.75 transdiameters at the widest part. The hypocone exceeds the epicone in size, its length
being greater by 0.16. The epicone is acorn-shaped with minute, acute apical point at the apex.
It has a length on the left and right sides of the body of about 0.38 and 0.5 respectively of the
total length of the body. The hypocone has a length of about 1.3 transdiameters, expanding
midway to about 1.16 transdiameters in width. The antapex is low conical with a club-shaped
tentacle extending posteroventrally from its tip.

The girdle is complete, forming a descending left spiral abruptly curved posteriorly at its
distal 0.15 to a total displacement of 0.35 transdiameter. The furrow is deeply impressed with
slightly protuberant lips, with the anterior shelf undercut and the posterior sigmoid in optical
section. Its width for most of its course is about 0.05 transdiameter and in the distal 0.15 this
is reduced to a very narrow cleft which, however, completes the circuit. The transverse flagellum
does not reach beyond 0.75 of the cireuit. It is a fine ribbon thrown into minute undulations
traveling distally along its length. The pore for the transverse flagellum lies at the proximal
end of the girdle.

The suleus lies on the flattened ventral face and extends from within a short distance of the
apex posteriorly in a straight line to the proximal end of the girdle and thence with a sweeping
curve to the left posteriorly to the antapex, ending at the junction with the tentacle. No pore
for a longitudinal flagellum was detected. Apparently in lieu of the usual threadlike posterior
or longitudinal flagellum this species in common with Protodinifer tentaculatum has a stout
tentacle-like prolongation on the posterior end of the body and ventral furrow. This tentacle

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 405

is club-shaped in Pavwillardia tentaculifera, 0.75 transdiameter in length and 0.12 in greatest
diameter, which is in the middle half of the length. At its proximal end it is constricted to half
its middle diameter and contracts distally to a blunt point. Throughout its entire length except
at the tip and base it is suffused with a brilliant, burnt orange brown color which is quite
uniformly translucent and shows no internal differentiation. It is habitually carried in an
oblique position about 30° ventrally from the axis, slightly arched with the concave side ventral.

The surface of the body is covered with a thin pellicle with a narrow clear zone beneath
except at the poles where this is obliterated. A few minute yellowish platysomes are scattered
somewhat irregularly near the surface and several linear ones mark out (faintly) several striae
on the right side of the longitudinal furrow on the epicone.

The cell contents consist of the nucleus located slightly in front of the middle of the body.
This is large, 0.66 transdiameter in diameter in dorsal or ventral view and 0.5 in lateral view,
due to the cup-shaped depression on the posteroventral face. It is double-contoured, with a
heavy membrane and is packed full of extraordinarily thick chromatin threads slightly modu-
lated. Sixteen of these strands, possibly not all distinet, are to be counted on the dorsal face.
There is evidence of polarization of the strands. Running posteriorly from the flagellar pore
at the proximal end of the girdle is a short canal leading towards a slender conical pusule,
probably collapsed, but not clearly connected with the canal. The dorsal surface has a suffused
rosy tone from certain radial accumulations of reddish substance located peripherally. A cluster
of minute red spheres is lodged near the antapex. There is no trace of a lens or pigment mass
such as are found in the eyespot of Pouchetia. No distinct chromatophores could be detected,
though the body as a whole has a pale yellowish tone. Neither rhabdosomes nor oil drops were
noted in the individuals under observation. The brilliant brown tentacle makes the animal a
conspicuous object in the microplankton. Luminiscence not tested.

Dinensions.—Length, 58; transdiameter at girdle, 274, at widest part of
hypocone, 31+; length of tentacle below antapex, 19; axis of nucleus, 194 and
13e.

Brnavior.—Cytolysis ensues in ten to fifteen minutes under illumination
in the microscope with ordinary daylight, the tentacle persisting entire nearly
as long as the nucleus but neither surviving more than a minute after cytolysis
sets in. The behavior of the motile organism is much like that of Protodinifer
described above. The tentacle is somewhat more mobile, being raised frequently
to a right angle to the axis or even above this and jerked back with a convulsive
jerk. Rotation in the anticlockwise direction is frequent with a gliding anterior
movement which must be due to the posteriorly directed current in the ventral
furrow. The body is somewhat metabolic. In one individual under observation
small protuberances of the body were thrust out on the dorsal and postero-
dorsal part of the hypocone and quickly retracted, without immediate patho-
logical consequences.

OccuRRENCE.—This was taken July 2, 1917, with a No. 12 silk net, 6 miles
off La Jolla, California, in a haul 60 meters to the surface and in a surface
temperature of 20°5 C. On July 20 it was again noted in a haul 6 miles off-
shore from 80 meters to the surface, and on July 25, 11 miles offshore, and on
July 27, 4 miles offshore in hauls from 80 meters to the surface and surface
temperature of 21°9 C. It was present in hauls made in the previous summer,
and was also observed by the senior author in plankton from a red-water out-
break off La Jolla in July, 1907.

406 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Comparisons.—Pavillardia tentaculifera differs from Gymnodinium pseudo-
noctiluca Pouchet (1892b) in being smaller, 58« instead of 110 in length, in
having a brown instead of a colorless tentacle and in shape and location of the
girdle. This is farther anterior and more strongly deflected posteriorly on
both ends in Pouchet’s species, and in the distal end only in P. tentaculifera.
Furthermore the epicone is relatively much smaller than the hypocone in his
_ species than it is in the one here described. It shares with this species the
tendency of the distal end of the girdle to be strongly deflected posteriorly, and
to be reduced nearly to obliteration distally. In this respect they both show
earlier stages in a degeneration process (or possibly earlier ones in a develop-
ment one) which progresses still farther in Protodinifer and Noctiluca.

The general form of the body, the structure of the girdle and the tendeney
to striation recall conditions in Gyrodinium, especially in species close to
Gymnodinium in the matter of degree of displacement of the girdle.

It is possible that Pouchet’s (1892b) Gymnodinium pseudonoctiluca should
be transferred to this family, though hardly to the genus Pavillardia. Its
‘“‘tentacle’’ appears to be more like a lateral suleal pseudopodium and much less
like a median tentacle such as those of Noctiluca and Pavillardia. Pending
fuller knowledge of such pseudopodia in Gymnodinium it seems wise to leave
Pouchet’s species in that genus.

NOCTILUCA Suriray

Not ‘‘Noctiluca marina’’ Adler (1852). Not binomial. Annelid.

Not ‘‘Noctilueca marina’’ Linnaeus (1758), p. 654, synonym of Nereis noctiluca; nor
‘‘Noctiluea marina’’ Linnaeus (1764), pp. 3, 203, reprint by Adler. Ed. 3 in 1787.
Annelid.

‘‘Medusa marina’’ Slabber (1771, fide Ehrenberg, 1834 for date), p. 67, pl. 8, figs. 4, 5;
not binomial name. Also edition dated 1778.

?Nereis noctiluca Miller, O. F. (1776), p. 217, in part.

Gleba Bruguiére (1791), pl. 89, figs. 2, 3.

Medusa scintillans Macartney (1810), pp. 264-265, pl. 15, figs. 9-12.

Slabberia Oken (1815).

Noctiluca miliaris Suriray Mss, Lamarck (1816), pp. 470-472.

Mammaria scintillans. Ehrenberg (1834), p. 559.

?Physematium atlanticum, Meyen (1834), p. 163, fide Ehrenberg (1834), p. 522.

Noctiluca miliaris Suriray (1836), pp. 1-16, pls. 1-2.

DIAGNOSIS

The body is inflated subreniform to spheroidal; distinction between epicone
and hypocone obliterated, in the adult, by loss of girdle resulting from inflation
by hydrostatic vacuoles. Sulcus deeply reéntrant, the medium cytostomal
region extended anteriorly in the straight apical trough, girdle represented
only by its proximal remnant; longitudinal flagellum short, transverse flagellum
reduced to a projecting mobile tooth; tentacle at posterior end of sulcus; cyto-
plasm vacuolated, anastomosing mobile strands move from periphery to central
mass containing nucleus; colorless or bluish green, sometimes tinged with yellow

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 407

in central mass. Multiple fission produces zoospores with girdle, one flagellum,
and tentacle. Diameter, 200-1200#. Cosmopolitan in neritic, marine plankton.
One species, Noctiluca scintillans, the type of the genus.

COMPARISONS

This genus differs markedly from Pavillardia in the excessive vacuolation
of its cytoplasm, in the degeneration of the girdle, reduction of the transverse
flagellum, and deep excavation of the suleus in the region of the cytostome.
These contrasts result from the inflation due to the hydrostatic vacuoles.

It resembles Pavillardia in the posteriorly located tentacle and in the be-
havior of this organ, as well as in the extension of the sulcus from near the apex
to near the antapex.

SYNONYMY

This is discussed in connection with that of the only species, Noctiluca
scintillans Macartney. The flagellate described from fresh water by Fabre-
Domergue (1889), as Pronoctiluca pelagica, does not appear to be a dinoflag-
ellate or to have any immediate relation to this genus.

There is but one valid species in the genus, N. scintillans, which is here
designated as the type. All others described in the genus appear to be
synonyms.

Noctiluca scintillans (Macartney )
Text figures KK, 1-6

‘‘Medusa marina’’ Slabber (1771, fide Ehrenberg, 1834, for date), p. 67, pl. 8, figures 4, 5.
Medusa scintillans Macartney (1810), pp. 264-265, pl. 15, figs. 9-12.
Slabberia Oken (1815).
Noctiluca miliaris Suriray Mss, Lamarck (1816), pp. 470-472.
Mammaria scintillans, Ehrenberg (1834), p. 559.
‘‘Noetiluea marina,’’ Ehrenberg (1834), p. 559.
Noctiluca miliaris Suriray (1836), pp. 1-16, pls. 1, 2.
N. banksii? var., Ehrenberg (1834), pp. 509, 510. Lapsus for Noctiluca, a crustacean.
N. punctata Busch (1851), p. 199, fig. 1.
N. omogenea Giglioli (1870), p. 490.
N. pacifica Gigholi (1870), p. 491.

Dracnosis.— Body inflated, vacuolated, broadly reniform to subspheroidal;
girdle reduced to proximal remnant; sulcus forming reentrant cytostome, ex-
tended anteriorly to apex in a straight trough; longitudinal flagellum short,
transverse one reduced to a mobile tooth; prehensile tentacle at posterior end
of suleus; nucleus with beaded chromatin, cytoplasm containing nucleus massed
near suleus; seattered phosphorescent oil globules, pellicle firm; no chromato-
phores; nutrition holozoic. Small zoospores with longitudinal flagellum, girdle
and tentacle, formed by multiple fission. Diameter of adult, 200-1200/, rarely
20004. Cosmopolitan in neritic, marine plankton.

Fig. KK. Noctiluca scintillans (Macartney). 1. Dorsal view showing apical trough. After Allman (1872,
pl. 18, fig. 1). X 125. 2. Lateral view from the left side showing the deep oral pouch. Modified after Allman
(1872, pl. 18, fig. 2). X 125. 3. Posteroventral view showing sulcus, girdle, undulating membrane or tooth,
flagellum and tentacle. The anterior lip is at or near the upper margin of the figure. Modified slightly after
Robin (1878, pl. 36, fig. 4). > 100. 4a, b. Zoospores. After Cienkowsky (1873, pl. 6, figs. 38, 42). X 500.
5. Noctiluca in chain at mitosis showing girdle in the anterior schizont. After Robin (1878, pl. 41, fig. 24).
125. 6. Midventral view showing sulcus, rudimentary girdle, transverse flagellum or tooth, longitudinal
flagellum and tentacle. Modified after Webb (1855, pl. 6, fig. 7). Magnification not given. Abbreviations:
ant. l., anterior lip; ap. tr., apical trough; g., girdle; I. fl., longitudinal flagellum; o. p., oral pouch; t., tooth or
transverse flagellum; tent., tentacle.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 409

Description.—The body has various shapes, depending upon the degree of its inflation, age,
and food contents. It is especially liable to deformation and wrinkling, due to contraction and
local collapse of the periphery on capture and standing in the laboratory. The girdle rarely
affects the form materially, and even the suleus fades out with the rounding up in old individuals
and as cytolysis approaches. The dinoflagellate structures, the girdle and suleus, as well as the
effect of these upon the form of the body, are shown more clearly in the smaller individuals.
The smaller individuals have a proportionately deeper suleus and a more reniform contour than
the Jarger ones, which tend to be more spheroidal, with only a slight flattening and shallow
excavation along the suleus. Collapsed, or non-distended, small individuals may have the
anterior ends extended and somewhat pointed, or even flattened, by the rather rigid, barlike
extension of the precingular trough of the suleus, and the posterior end may be extended by its
postcingular extension, terminating in the tentacle.

In typical, distended, small (400u) individuals (fig. KK, 1) the body is broadly subreniform,
with the transverse diameter slightly exceeding both the dorsoventral and the longitudinal ones.
There is, however, much variation in proportions, due to contraction and collapse. The ventral
surface is deeply incised by the strictly longitudinal, median suleus, which terminates posteriorly
in the tentacle and runs thence anteriorly in a straight line to its termination in the straight
apical trough, at or beyond the morphological apex of the epicone. The depth of the suleus
varies in the several regions and is unlike in different individuals, according to the degree of
recession of the eytostome which lies in its deepest midventral region.

There are two main regions of the sulcus, the oral pouch containing the cytostome and the
apical trough. The oral pouch, when fully retracted (fig. KK, 2, 0. p.), is a deep median pocket,
laterally compressed, at the bottom of which les the central protoplasmic mass. The tentacle
is placed at its posterior end, the longitudinal flagellum traverses it lengthwise, the tooth lies
on its left face, and the proximal end of the girdle creases its left side. In lateral view the floor
of the oral pouch runs anteriorly from the base of the tentacle to a level slightly above that of
the equator, where it turns abruptly ventrad at right angles, forming the anterior lip (fig. KK, 1,
ant. 1.) at a level with the general contour of the body. The cytostome les in the bottom of the
oral pouch, as a linear region through which food is taken. Its exact limits are unknown.

The apical trough (fig. KK, 1, ap. tr.) is the continuation of the sulcus anteriorly towards
the apex. It emerges from the oral pouch over the anterior lip as a converging tract, and is
continued as a narrow, straight, shallow furrow to its abrupt termination near the apex. It is
supported below the pellicle by an accumulation of protoplasmic processes and a thickening of
the peripheral protoplasm. The trough may be slightly elevated above the general contour, and
appears to be a rather rigid structure. There is no evidence that it can function as a cytostome,
as does some part of the sulcus within the oral pouch.

The suleus in other dinoflagellates with spiral girdle may be divided into precingular, inter-
cingular, and postcingular regions. These regions are recognizable in Noctiluca. The pre-
cingular one includes the apical trough and that part of the sulcus within the oral pouch which
passes over the lip into the pouch and posteriorly to the proximal end of the girdle near the
tooth. <A part of it within the oral pouch may function as a part of the cytostome. The inter-
cingular region is ill-defined owing to the absence of the distal end of the girdle. There is little
if any spiral deflection of the girdle in the zoospore and no evidence of such deflection in the
degenerate girdle of the adult.. The distance between the proximal end of the girdle (fig. KK,
3, gir.) and the origin of the longitudinal flagellum which, in most dinoflagellates, represents
approximately the point of union of the distal end of the girdle with the suleus may be held to
represent the intercingular part of the suleus in Noctiluca. The posteingular part extends
from the origin of the longitudinal flagellum to the tentacle.

The girdle (fig. KK, 3, gir.), present in the zoospores (4) as a constriction below the sub-
hemispherical epicone, completely encircles the body. In the adult the girdle is degenerate,

410 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

and, though figured by Webb (1855, pl. 6, fig. 6) and Robin (1878, pl. 36, fig. 4; pl. 41, fig. 24),
it otherwise escaped their attention, as it has that of all other investigators of Noctiluca. We
have found this structure repeatedly in living Noctiluca and regard it as the proximal end of
the girdle and not a mere wrinkle due to contraction. Its constancy in position, when present,
its well marked borders and the supporting peripheral cytoplasm confirm this interpretation.
Its location and morphological relations are precisely those of the proximal end of the degenerate
girdle. It is a shallow, arched trough, arising on the left side of the sulcus just anterior to the
base of the longitudinal flagellum and adjacent to the tooth. It makes from 0.08 to 0.20 turn
about the body, dying out distally. It lies near the level of the equator and marks the line of
incomplete separation of epicone and hypocone which, in Noctiluca, would thus be subequal.

The transverse and longitudinal flagella are represented respectively by the tooth and the
small longitudinal flagellum. The former (fig. KK, 3, tent.) is a small mobile projection which
lies at the left and slightly anterior to the base of the longitudinal flagellum, adjacent to the
proximal end of the girdle in the edge of the suleus. It is a somewhat rigid, striate membrane,
overarching the suleus to its right. Its form varies in published figures and in individuals
which we have observed. In its most reduced form it is a small, low, ragged ridge. It may
form only a single arched tooth, or a bifid one, or a series of two or three teeth, increasing in
length anteriorly, or it may rarely appear as a rather ragged tapering or broad and ribbon-like
process half as long as the longitudinal flagellum projecting free into the suleus. In life it is
subject to spasmodic downward strokes into the adjacent suleus and to minute changes in out-
line. It is not, as we have seen it, freely undulating as is the transverse flagellum typically, but
rather rigid and slow in movement. It appears to be a transverse flagellum adapted as a
prehensile organ for the capture and ingestion of organisms taken as food. For this function
it has become more rigid and has lost its distal extension, locomotor function, much of its
mobility, and its location in the girdle. It lies in the suleus immediately adjacent to the proximal
end of the degenerate girdle and runs longitudinally instead of transversely. However, it is
longest near the end of the girdle. No trace of it is shown in the zoospores by Cienkowsky (1871),
Robin (1878), or Ishikawa (1899), provided that the tentacle-like structure shown by Cien-
kowsky and Ishikawa becomes the tentacle of the adult, as seems probable. No account of the
transformation of the zoospores into the adult is available.

The longitudinal flagellum (fig. KK, 3, long. jl.) is of the usual form, a simple thread. It is,
however, much reduced in length and lies hidden in the oral pouch and is often lost or entirely
overlooked. It has little or no function in locomotion.

The tentacle (fig. KK, 3, tent.) is the most prominent organ of Noctiluca. It arises from
the posterior end of the suleus as a slender process of nearly uniform diameter, from 0.5 to 0.2
the diameter of the body in length. Its diameter is about 0.24 its total length and is slightly
increased towards the base. Its distal end is bluntly rounded. It is not cylindrical in eross-
section, but flattened, with its dorsal surface convex and the ventral one concave, as though the
suleus were continued upon it. Its dorsoventral diameter is about 0.35 its transverse one. It
is transversely striate with close-set, evenly spaced protoplasmic net work, especially in its concave
or ventral half, which is its contracted side. It is very fragile, easily broken off, and not infre-
quently missing in living as well as in preserved material. It is thrown in wide undulations in
the vertical plane or in a loose spiral coiled anteriorly. These undulations pass distally, and
when the tentacle rests upon an obstacle the body is thrust away from it by the action of the
tentacle. The undulations tend in some instances to push objects up into the suleal region.
The base of the tentacle passes over into two laterally spreading fibrillar processes which form
a supporting framework for the organ attached to the pellicle.

The cytoplasm is greatly distended by hydrostatic vacuoles in adaption to flotation. It is
massed about the nucleus adjacent to the cytostome. This mass sends peripherally to the pellicle
slender, branching, and anastomosing strands of protoplasm which unite with a thin network
of peripheral cytoplasm. Scattered through the mass of cytoplasm, in the radial strands and

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 411

in the periphery, are numerous small oil globules, the centers of the liminescent activity of the
animal.

There are no chromatophores. The color is an opalescent greenish blue, sometimes tinged
with yellowish green, or even ochraceous yellow in the central mass of cytoplasm.

Nutrition is holozoic. Noctiluca is omnivorous, capturing active organisms such as Peri-
dinium, Gonyaulax, and nauphi, as well as passive diatoms, metazoan ova, and even engulfing
inorganic particles such as small grains of sand.

Multiplication by binary fission is frequent. This results in typical dinoflagellate chain
arrangement of the two daughter organisms (fig. KK, 4), although the movements of ‘the
tentacles and approaching plasmotomy soon obscure this relation. Early binary fission was
misinterpreted by Ishikawa (1891) as conjugation. Doflein (1916) states he has seen complete
fusion of cytoplasm and nuclei of two individuals. Mitosis (see Ishikawa, 1899; Calkins, 1899 ;
Doflein, 1900; and Jollos, 1910) is of the dinoflagellate type, with large sphere and beaded
chromosomes, but the beaded condition is most evident at mitosis.

Multiple fission results in the formation of numerous zoospores (fig. KK, 3) with girdle,
longitudinal flagellum, incipient tentacle, and the general appearance of a small dinoflagellate,
but with no transverse flagellum.

Dmrenstons.—Diameter, 400-1200", rarely 200-2000; zoospores, length,
25-30; transdiameter, 10—-15v.

OccuRRENCE.—Abundant in San Diego Bay, San Pedro harbor, San Fran-
cisco Bay, and Puget Sound, and less so in the plankton off the Pacific Coast
of the United States, throughout the year, but more abundant in summer and
autumn. It is apparently cosmopolitan in the neritic plankton of temperate
and tropical seas, but not typically pelagic in the high seas. It is not men-
tioned in Hensen’s (1911) summary of the findings of the Plankton Expedition.
Karsten (1905a, b, 1907) lists it in the Valdivia collections only from coastal
regions. Parker and Haswell’s (1897) statement that Noctiluca is the cause
of the diffused phosphorescence of the sea should be modified by the restriction
to one of the causes of phosphorescence in neritic waters. “‘Pyrocystis’’ re-
places it in the plankton of the high seas.

SynonyMy.—The nomenclature of Noctiluca is fraught with difficulties
arising from fragmentary and incomplete descriptions by the earlier observers,
confusion, on their part, of Noctiluca with other phosphorescent organisms, as
well as by its description under various names. The name Noctiluca miliaris
has, except for the deliberate reallocation of the organism by Ehrenberg (1834),
held almost undisturbed sway in practically all the voluminous, original liter-
ature and in widespread citation in standard texts since 1816, when Lamarck
used Suriray’s manuscript name in his Animaux sans vertebres. The law of
priority clearly calls for the specific name scintillans Macartney (1810), but
the determination of the generic name is fraught with difficulties. Any name
other than Noctiluca rests on the most unstable premises, and even it is of
questionable validity.

The most extended discussion of the status of Noctiluca is found in the
exhaustive review by Ehrenberg (1834) in his Das Leuchten des Mecres, though
it is not made with a view to priority under any code of nomenclature. From

412 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

this review and a survey of all available literature it appears that Noctiluca
may be found in the older literature under the following generic names:
Nereis (?), Medusa, Mammaria, Gleba, Slabberia, and Physematium, prior to
Lamarck’s publication of Suriray’s Noctiluca in 1816. All figures and deserip-
tions prior to Slabber’s (1771, fide Ehrenberg, 1834, for date) account of his
“Medusa marina” (his plate 8) are so imperfect as not to be recognizable with
certainty as Noctiluca. Slabber’s nomenclature is clearly not intentionally
binomial. His figure is recognizable as Noctiluca. Oken (1815) gave it the
generic name Slabberia, but with the rejection of Slabberia as doubtfully ten-
able Noctiluca comes next as claimant for priority, and may be accepted even
though some extremist might hold that Linnaeus’s use of Noctiluca marina in
Ed. 10 (1758) of his Systema Naturae as a synonym in binomial form of his
Nereis noctiluca (annelid), establishes Noctiluca as a genus. Publication of
the name in the later edition (1787-1790) of his Amoenitates Academicae, in
which he republishes Adler’s (1752) paper on ‘* Noctiluca marina’ in which
these words are used as a title and not as a binomial name of the annelid worm
described in the paper, might also be used in support of the preoccupation of
Noctiluca Suriray by Adler’s name. We reject this interpretation since Adler’s
use of the words in binomial form was not an intentional binomial naming of
the worm.

The first valid specific name appears to be Macartney’s Medusa scintillans,
published in the well known Transactions of the Royal Society of London
(1810). Its priority was recognized by Ehrenberg (1834) and later by Mobius
(1861). The date of Macartney’s paper is incorrectly stated in Carus and
Engelmann’s Bibliotheca Zoologica (1861, vol. 1, p. 294) as 1820. Macartney’s
account and figures are sufficiently complete to afford a recognition of the
organism. The tentacle is suggested, though not clearly described, and is
figured faintly (his pl. 2, fig. 12).

Later Ehrenberg (1834) decided, on grounds not clearly stated, that the
name should be Mammaria scintillans. The genus Mammaria, founded by O. F.
Muller in 1776 for imperfectly described coelenterates, is so inadequately known
as to be unrecognizable. It is evident that Muller’s (1776) citation of ‘‘N. act.
N. Curios, vol. 4”? is incorrect. No previous publication of Mammaria can be
located in the memoirs cited by him. The allocation of Noctiluca therein is with-
out any satisfactory basis of discussion or revision of the genus by Ehrenberg.
We reject his allocation as untenable.

In the course of his discussion Ehrenberg sometimes (1834, p. 559) loosely
used the phrase “‘Noctiluca marina” in italicized binomial form simulating a
generic-specific combination of names, without, apparently, intending to give
it binomial status.

Noctiluca banksii var. of Baird (1830, fig. 100a) is a crustacean Noctiluca
and was cited by Ehrenberg (1834, p. 510) as Noctiluca banksii? var.

Busch (1851) based his species of N. punctata upon the punctate appearance
which he observed, but this is not a species character.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 413

Giglioli (1870) describes two new species of Noctiluca, N. omogenea and
N. pacifica, but neither appear to be distinct from N. scintillans.

There appears thus to be but a single species, Noctiluca scintillans
(Macartney), in this genus. It is evident that this name is the only one de-
fensible under the code of nomenclature. It is the type of the genus Noctiluca.

Comparisons.—It is obvious that the adaptation of Noctiluca to passive
flotation by hydrostatic vacuoles has brought about profound modification of
structure. The locomotor organs, the two flagella, are no longer functional as
a rotater and propellor respectively. The longitudinal flagellum is hidden in
the reéntrant atrium and the transverse one is reduced to a mere prehensile
tooth. With the degeneration of the latter the girdle disappears, except for
its proximal region, and the separation between epicone and hypocone is lost.
The suleus is developed as a large cytostome and the form of the body, as a
result of inflation by the vacuoles, loses all marked dinoflagellate characteristics,
except as indicated by the sulcus.

The tentacle in its location, structure, and function is foreshadowed or
paralleled by the pseudopodium-like tentacle of Gymnodinium pseudonoctiluca,
the tentacle of Pavillardia, the incipient prod of Proterythropsis, and the fully
developed one of Erythropsis. This tentacle of Noctiluca can not be the homo-
logue of these structures and at the same time represent the transverse flagellum,
as Biitschli (1885) proposed, since the transverse flagellum is present in other
tentaculate dinoflagellates and is fully functional. It is rather, as Kofoid (1919)
has shown, not a homologue of either flagellum, but a derivative of the margin
of the suleus as are the other tentacles of the dinoflagellates. There is no
satisfactory evidence that the tentaculate dinoflagellates form a coherent family,
but rather that they are of independent origin in several families. It is still
probable, however, that the tentacles are to be regarded as homologous organs
throughout the series.

CHAPTER XVIII

POUCHETIIDAE: PROTOPSIS, NEMATODINIUM
Family 5. POUCHETIIDAE fam. nov.

DraGNnosis.—Gymnodinioidae with ocellus located on left side of the inter-
cingular sulcus, consisting of a lens and melanosome or pigment mass; epicone
and hypocone are subequal; girdle and sulcus with more or less torsion; pusules
usually present; plasma usually colored. Length, 32-141». All eupelagie and
marine and are known principally from warm temperate and tropical seas and
rarely in purely neritic waters.

DESCRIPTION

The ocellus is located on the left side of the intercingular sulcus, and consists
of a lens and melanosome or pigment mass, the latter often amoeboid, and
usually differentiated in the center into a red, brown, or yellow region or
sensory core. The pigment mass is red throughout in some instances. The
epicone and hypocone tend to be subequal except in Erythropsis, where the
epicone is reduced. The girdle and sulcus in some cases show considerable
torsion, and the latter often has an apical and an antapical loop. Paracingular
lines are present in Erythropsis. Varying degrees of integration of the ocellus
occur throughout the genera of this family. Nematocysts are present in
Nematodinium. A posteriorly directed prod or tentacle is formed in Protery-
thropsis and Erythropsis. Pusules are often present, opening anteriorly into
the anterior and posteriorly into the posterior flagellar pores. The nucleus
generally lies anterior to the ocellus and may or may not have a perinuclear
membrane. Longitudinal striae on the surface of the body are rarely present.
Vacuoles tend to form in the peripheral plasma.

The plasma is often highly colored, especially peripherally. Cyst formation
is very frequent, the closely adherent membrane becoming distended after its
formation by an intramembranous fluid. The body itself within the cyst does
not become inflated with intracytoplasmic vacuoles.

It contains five genera: Protopsis with 3 species, Nematodinium with 3,
Pouchetia with 20, Proterythropsis with 1, and Erythropsis with 10, making a
total of 37 species. Of these five genera three are new, Protopsis, Nemato-
dinium, and Proterythropsis. Erythropsis was described by Hertwig (1884),
though its affinities with the Dinoflagellata long remained unrecognized, and
Pouchetia was proposed by Schiitt (1895) for the ocellate Gymnodinioidae,
including two species now referred to Erythropsis, whose affinities he did not
recognize.

[414]

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 415

KEY TO THE GENERA OF THE Pouchetiidae

1. Gymnodinium- or Gyrodinium-hke, girdle without displacement, suleus without torsion —.-
a a Re ee ee Protopsis gen. nov.

. Girdle displaced in a descending left spiral, suleus with some torsion — 2
SEG eI aL OCY Sts meee eee eee Nematodinium gen. nov.
PRAT OU EMCI a LOGY SUS tem eames cans nee tect nee wa eS ee eat AS Ne 3

. Without posteroventral prod or tentacle _.. ..-Pouchetia Schiitt
wy NATH POR ECO CG A i ae ed occ eee Re eRe re a ee ee ee 4
. Epicone and hypocone subequal, no paracingular lines -........... Proterythropsis gen. nov.

Hm BP CO OO Nh He

. Epicone less than hypocone, paracingular lines present —.................. Erythropsis Hertwig

PROTOPSIS gen. nov.
Text figure LL

DraGnosis.—Pouchetiidae with the girdle and sulcus of the Gymnodinium
or Gyrodinium type with simple or compound ocellus, no tentacle, no apical
loop of the sulcus, and no torsion of the body. Girdle does not make more than
one turn around the body. No paracingular lines. Posterior flagellar pore
not located far posteriorly. Three species, all eupelagic and marine. Type,
Protopsis nigra (Pouchet).

DESCRIPTION

To include as Lemmermann (1899) has done in the one genus Pouchetia
all Gymnodinioidae with an ocellus but no tentacle is fraught with extreme
difficulty when an attempt is made to define this inclusive genus. Since the
course and differentiation of the girdle and sulcus is so largely utilized in
generic distinctions, it seems both logical and consistent to apply these criteria
within the ocellate forms. This necessitates the separation of those species
without torsion of the sulcus or its extension in an anterior loop, and with
far posterior location of the posterior flagellar pore, from those having these
striking modifications in structure.

The group of simpler Pouchetiidae thus detached from the more complex
ones contains but two species, both previously described and imperfectly known,
that of Pouchet’s (1887, pl. 10, figs. 2 A, B, 3, 4) Gymnodinium polyphemus
var. nigrum, and that of Wright (1907, pl. 1, fig. 8) Pouchetia ochrea. The
former is the type species of the genus Protopsis. To these a third new species,
P. neapolitana, is added.

It is significant of the possible mode of evolution of the more complex
Pouchetiidae that Protopsis nigra has a compound ocellus with several lenses
and lobed melanosome, while P. ochrea has at least a lobed melanosome and
P. neapolitana a finely divided one.

This fact taken in conjunction with the simplicity and primitive stage of
differentiation of sulcus and girdle in Protopsis suggests that the divided con-
dition of the ocellus and melanosomes may be the more primitive one since it is

416 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

found in association with the primitive or Gymnodinium- or Gyrodinium-like
condition of such fundamental structures as the ordinal characters, the sulcus
and the girdle. This genus differs from Pouchetia in the absence of apical loop
of the sulcus, lack of torsion, and short intercingular region of the sulcus. It
differs from Erythropsis in the lack of apical loop, paradinial lines, tentacular
recess and tentacle. It is plainly the least specialized genus of the Pouchetii-
dae. It is noteworthy that within this genus, as also in Pouchetia and Eryth-
ropsis, there are two lines of differentiation, namely, into the compound and
simple types of ocellus. Speciation has followed parallel courses in the three
genera.

Fig. LL. Protopsis gen. nov. 1. P. nigra (Pouchet). After Pouchet (1887, pl. 10, fig. 2 A). 2. P. neapoli-
tana Kofoid. 3. Same rounding up. 4. P, ochrea (Wright). After Wright (1907, pl. 1, fig. 8). X 500.

Key TO THE SPECIES OF Protopsis GEN. NOV.
Ts (Ocellus dufkuse ys = 5 ee ee: es ee ee ee pa eEhGS BEG oe. 2
1. Ocellus concentrated, with single campanulate lens, no scattered peripheral pigment -.......
oo LE GE Ee a SORES EES ee ee ochrea (Wright)
2. Ocellus with 4-6 spheroidal lenses, ragged melanosome and scattered pigment in peripheral
Plasma’ :-24) se ee ee LE ee ER Rar ee ee cee nigra (Pouchet)

bo

. Ocellus with single lens, melanosome composed of a cluster of granules —.....-.---2.---.-
sep untle dae ah ie ee ge ll Pe ee ee ie ee eee neapolitana sp. nov.

Protopsis neapolitana Kofoid MSS.
Plate 9, figure 96; text figures LL, 2, 3

DracNosis.—Small species, body ovoidal, its length 1.45 transdiameters;
apex pointed; girdle a steep descending left spiral, displaced 0.68 total length;
ocellus centrally located, lens subovoidal, flattened against small melanosome
composed of clustered granules and 0.5 diameter of lens; plasma almost color-
less; holozoic. Length, about 504. Mediterranean at Naples, January.

DescripTion.—The body is ovoidal, slightly wider posteriorly, its length 1.45 transdiameters
at the widest pomt which is postequatorial. The epicone is exceeded by the hypocone by 0.25
length of the hypocone. Its length at the proximal and distal ends of the girdle is 0.09 and
0.67 total length respectively. The apex is rotund subconical, about 80° distally, rounding
almost to subhemispherical under the stimulus of strong light. The hypocone has a length of
0.91 and 0.33 total length at its anterior and posterior ends of the girdle respectively and the
antapex is almost hemispherical with no suleal notch.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 417

The girdle forms a steep, uniform, descending left spiral of about 30° from the horizontal.
It passes from its anterior Junction with the suleus 0.09 total length from the apex to its distal
junction 0.67 total length with little change in obliquity. Its total displacement is 0.58 total
length or nearly 1 transdiameter. The furrow is about 0.08 transdiameter in width and is
lightly impressed without prominent lips. The sulcus runs from near the apex almost to the
antapex, with only a slight sigmoid curve. The anterior flagellar pore is at the anterior junction
of girdle and sulcus and the posterior a girdle’s width below the posterior junction. The
transverse flagellum is less than 0.5 the length of the girdle and the posterior one 1.25 lengths
of the body in length.

The ocellus is 0.28 transdiameter in length and at the right of the center of the body. It is
diffusely organized. The lens is a broadly ovoidal, translucent body 0.22 transdiameter in length
and 0.9 of its length in width, and truneated at the end applied to the melanosome. There are
no laminae visible. The melanosome consists of a dense cluster of coarse black or very dark

=

brownish black granules clustered in a small hemisphere 0.5 diameter of the lens in diameter
applied to the center of the truncated anterior end of the lens.

‘The nucleus is a small ellipsoidal body lying obliquely in the posterodextral part of the
body. Its major and minor axes are 0.40 and 0.26 transdiameter in length respectively. It is
filled with coarse, beaded, chromatin strands running spirally about the major axis. No pusules
were noted. The body was crowded with food and the products of metabolism. Near the center
was a very large, ellipsoidal, fluid-filled vacuole of a very pale, ochraceous-salmon color. Crowded
about it were numerous highly refractive bluish green spherules of varying sizes; while crowded
into the posterosinistral corner was an ellipsoidal food ball of yellow ochre color with a brownish
mass within it. Faint traces of longitudinal striae could be detected on the surface.

Divensions.—Length, about 50; transdiameter, 34.

OcCURRENCE.—One individual observed in the plankton of the Bay of Naples
on January 27, 1908, by the senior author.

Activities.—The animal circled in close clockwise spirals several lengths
of the body in diameter. The transverse flagellum was seen to be thrown out
of the girdle and trailing behind the body, near the longitudinal one, as a spiral
band at times while the animal was moving. As cytolysis approached the distal
end of the longitudinal flagellum formed an amoeboid mass of plasma which
retreated towards its base. This organism was photosensitive to the illumi-
nation of the microscope, contracting into a more rounded-up form when
intensely illuminated and extending again into the pointed form of apex in
dimmer light.

CoMPARISONS.—This species has the Gyrodiniuwm type of girdle and suleus
while P. nigra (fig. LL, 1) has the Gymnodinium type and P. ochrea (fig. LL, 4+)
stands about midway between the two in this feature. This species is placed
in Protopsis rather than Pouchetia because of the absence of torsion in the
suleus. The ocellus also shows an advance in that the lens is a unit instead of
several asin P. nigra. It is, however, less hyaline than usual in such structures.
The melanosome is unique in being composed of a loose aggregate of uniform,
small, dark brownish black grains grouped in a small hemisphere on the trun-
cate end of the lens. It is relatively unusually small, having only 0.5 the diam-
eter of the lens and less than 0.1 its volume. The lack of integration in this
organ is also seen in the fact that it does not, at least in the single individual
observed, have the customary position near the periphery at the left of the

418 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

intercingular sulcus, but hes to the right and deep in the center of the body.
Its lens is also directed posteriorly. Its functional efficiency as an organ of
light perception can at the best be but slight.

Protopsis nigra (Pouchet)
Text figure LL, 1

Gymnodinium polyphemus var. nigrum Pouchet (1887), pp. 93, 97-104, 112, pl. 10, figs.
2 A, B, 3,4. Figures 2 C and 5 are not Protopsis nigra, but indeterminate. Figures
inverted.

G. polyphemus var. nigrum, Sechiitt (1895), p. 95.

Pouchetia nigra, Lemmermann (1899), p. 360.

P. ngra, Pavillard (1905), in part, pp. 47-48. P. juno tentatively included.

Gymnodinium polyphemus var. magna Dogiel (1906), p. 37. Lapsus for nigrum.

DraGnosis.—A medium sized species, body asymmterical ovoidal, its length
1.5 transdiameters; girdle equatorial, displaced 0.3 transdiameter; sulcus
straight, midventral; ocellus dispersed, with 5-8 spherical lenses, amoeboid
black melanosome and red core; plasma ochraceous with seattered black
granules in periphery. Length, 74". Coasts of France, spring and autumn.

Description.—The body is asymmetrically ovoidal, its length 1.5 transdiameters; epicone
and hypocone subequal. Epicone subhemispherical, apex broadly rounded, nearly symmetrical,
less rotund at the right. Hypocone a trifle smaller than the epicone, much less hemispherical,
prolonged at the right side, and with rounded antapex displaced to the left.

Girdle equatorial, forming a descending left spiral displaced about 0.3 transdiameter and
not overlapping in the intercingular area. The furrow is deeply impressed with prominent lips
and is about 0.12 transdiameter in width. The suleus does not appear to be fully delineated.
As shown, however, it appears to be nearly straight, midventral, and not extended far upon the
epicone. It flares distally.

The ocellus is dispersed or compound, consisting of five to eight spherical lenses of varying
sizes and grouping and an amoeboid pigment mass with black, lobed melanosome and small,
brilliant red, centrally located core. It is located opposite the intercingular region of the sulcus
and does not appear to be protuberant or so close to the sulcus as in any way to modify it. The
peripheral plasma is crowded with black pigment in the form of small granules and coiled rods
in the form of commas, hooks, and irregular semicircles, somewhat more finely divided on the
right side of the epicone and less abundant near the melanosome, thus exhibiting a polarization
in the direction of the plane of fission. The nucleus is ellipsoidal with its major and minor axis
0.6-0.8 and 0.37—0.66 transdiameter in length respectively. It exhibits the typical parallel
chromatic threads. The general color is dark olive ochre, but distinct chromatophores are not
indicated. Pouchet (1887) notes the resemblance of its color to diatomin. Often eneysted in
a closely fitting, transparent cyst.

Divenstons.—Length, 74; transdiameter, 45; length of ocellus, 154; diam-
eters of nucleus, 40” and 28+.

OccuRRENCE.—Abundant at Concarneau, France, in the marine plankton,
April 28 and May 2 and 3. Pavillard (1905) reports it (sensu latu) as rare in
the plankton of the Etang de Thau, at Cette, France, on the Mediterranean in
October and December. The surface temperatures range there from 18°4 C to
6°9 C in these months.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 419

ComParisons.—The ocellus and dimensions separate this from P. ochrea
(fig. LL, 4). Its ocellus is of the same general form as that in Nematodinium
partitum (fig. NN, 4), Pouchetia schuetti (fig. PP, 10), and Hrythropsis labrum
(fig. SS, 6), indicating parallel lines of evolution of the ocellus in the four
genera, Protopsis, Nematodinium, Pouchetia, and Krythropsis.

SynonyMy.—This species was originally described by Pouchet (1887) as
Gymnodinium polyphemus var. nigrum and represented one of two varieties
into which he divided his G. polyphemus (1885b, pl. 26, figs. III, 1V). Neither
variety, however, represents his original form in those characteristics which,
with fuller knowledge of these organisms, are now recognized as diagnostic,
and all three appear to be distinct species. The imperfections of Pouchet’s
figures and descriptions and his probable inclusion of more than one form
under one name, as, for example, in his G. polyphemus (1885b), add to the
difficulties In subsequent specific identifications of these forms. The results
are that later workers in this field, Schtitt (1895), Pavillard (1905), and Paul-
sen (1908), have added to the confusion and to the difficulties in synonymy.

Pouchet’s G. polyphemus var. nigrum, as originally figured (1887, pl. 10,
figs. 2-5), is distinctly ochraceous and possibly has chromatophores, though
none are figured as distinct structures. In so far as indicated the sulcus is
longitudinal, midventral, and without torsion. The peripheral cytoplasm con-
tains everywhere finely divided black chromatin in the form of commas and
semicircles of irregular shape. These, however, are lacking in his figures 2 ©
and 5 of an encysted form, in which also the eyespot is of a wholly different
type. It is here simple with stout clavate lens and hemispherical melanosome,
whereas in the other figures the ocellus is compound with five to eight spherical
lenses and an amoeboid pigment mass. In view of the fact that the structure
of the ocellus is diagnostic in the group as a whole, and in our experience is not
subject to changes within the individual and species so great as here indicated
by Pouchet, we conclude that he has included in this species another without
peripheral pigment and with simple ocellus. Since its sulcus and girdle are in
no way indicated their allocation is impossible. We therefore exclude from
Protopsis nigra (Pouchet) his figures 2 C and 5 as indeterminate Pouchetiidae.

Lemmermann (1899) allocates Pouchet’s Gymnodinium polyphemus var.
nigrum to Pouchetia and advances it to spectific status, both of which changes
Schiitt (1895), the authority for the genus, omitted to make, probably because
of the fact that he made no revision of forms belonging to Pouchetia, rather
than by reason of the structural peculiarities of P. nigra.

Pavillard’s (1905) tentative inclusion of Schiitt’s Pouwchetia juno in the
svnonymy of P. nigra appears to us wholly unwarranted by differences in
suleus, girdle, ocellus, coloration, and dimensions.

Paulsen (1908) makes the suggestion that Schiitt’s Pouchetia rosea
(Pouchet), which is not Pouchet’s species, may be P. nigra (Pouchet) Lemm.
As we indicate in our discussion of Schitt’s species which we regard as

420 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

P. schuetti nom. sp. nov., Schtitt’s (1895) forms differ from Pouchet’s (1887)
in having the torsion of Pouchetia and a rosy instead of an ochraceous plasma.
The ocellus of P. schuetti is compound as in Protopsis nigra, but none of
Schutt’s figures of his ‘‘P. rosea’’ has peripheral black pigment. As matters
stand Pouchet’s (1887) figures must be assumed to be correctly drawn until
some one rediscovers his species and critically reéxamines it in the light of
later data and these criticisms.

Protopsis ochrea (Wright)
Text figure LL, 4
Pouchetia ochrea Wright (1907), p. 4, pl. 1, fig. 8.

DraGcnosts.—A small species of rotund body, its length 1.2 transdiameters ;
girdle equatorial, displaced about 0.25 transdiameter; sulcus?; ocellus simple,
lens conical campanulate with terminal projection, melanosome lobed; chro-
matophores linear, ochraceous. Length, 554. Canso, Nova Scotia, July.

DescripTion.—Only one individual in binary fission prior to mitosis is figured by Wright
(1907), so that the possibility of an adequate comparative description is much restricted. The
body is rotund, its length about 1.2 transdiameters, with epicone and hypocone subequal.
Epicone subhemispherical, hypocone less hemispherical with antapex slightly longer at the right,
but broadly rounded.

Girdle nearly equatorial, not overlapping, without torsion of the body, intercingular dis-
placement about 0.25 transdiameter, furrow shallow with prominent lips. Suleus not figured,
but probably nearly straight and midventral.

Ocellus simple, located at the left of the intercingular suleus with its main axis oblique,
deflected about 40° from the median plane to the right anteriorly, its length 0.4 transdiameter.
Lens simple with campanulate base bearing a short, terminal, anteriorly directed stem about half
the length of the base, the bottom of which is buried in the shallow melanosome which bears on
its posterior face five or six simple or branched lobes or processes. Chromatophores ochraceous,
in strands as in Sechiitt’s Gymnodinium geminatum. Nucleus (food ball?) ellipsoidal, its length
about 0.33 transdiameter. Binary fission in close fitting gelatinous cyst.

Divenstons.—Length, 554; transdiameter, 454; length of ocellus, 22+.

OccuRRENCE.—Common in the plankton at Canso, Nova Scotia, in July,
1901-02 (Wright, 1907).

Compartsons.—Differs from all known Pouchetiidae in having chromato-
phores and therefore in being in all probability holophytic. The type of ocellus
distinguishes it at once from the other species of this genus, P. nigra (Peouchet).
However, the pecuhar form of the lens and the much lobed melanosome are
indicative of a near approach to or only a slight differentiation from the com-
pound type. This species also lacks the distributed peripheral pigment strands
so characteristic of P. nigra (fig. LL, 1).

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 421

NEMATODINIUM ven. noy.
Text figures MM, NN
DIAGNOSIS

Pouchetiidae with nematocysts; girdle with more than 1 turn, displaced
more than 0.5 transdiameter; sulcus with torsion of 0.75 turn or more with a
posterior turn on the dorsal side of the antapex; no paracingular lines; ocellus
distributed or concentrated, located far posteriorly ; eupelagic, marine, holozoic.
Type species Nematodinium partitum sp. nov.

As yet only three species are known in this _ epi.-------,
genus, i.e., N. armatum (= Pouchetia armata — sule._----- ae n.
Dogiel, 1906), from the marine plankton off 7em.----- a,

Naples, Plymouth, and La Jolla, and N. tor- 2##. p.---tay- <T cases
pedo and the type, N. partitum, from off La - \

Jolla. This small number of species renders gir ______ ‘sinterc. a.
further generic characterization superfluous. rod. - ~~~ - ;
hyp---=--—— p.-------- 1.
COMPARISONS Sree oN Re fea mel.

. The diagnostic characteristic of this genus TASSEMEAE | NOREADGINGOR ERT REN Ok
is the possession of nematocysts clustered nov. Abbreviations: ant. p., antapical pore;
about. the nucleus. These are known else- ?» epicone; gir, girdle; hyp., hypocone;
where in the Dinoflagellata only in Polykri- See tae ee eae
kos. These nematocysts are small, sometimes some; n., nucleus; nem., nematocyst; rod.,
slightly capitate, tapering, peg-shaped bodies, coe Spee Ueda ereneuer serie,
5u to 22 in length, filled with fluid with an in-

trovert consisting of a cone contracting to a straight axial tube extending nearly
to the opposite end of the body, where it turns abruptly and coils about the
axial shaft in a close flat spiral. On discharge the tube is presumably everted
as a long coiled thread. The presence of these complex structures affords a
sufficient basis for generic distinction. There is no evidence that these organs
are introduced from extraneous sources.

Associated with the presence of these organs is the extreme posterior location
of the ocellus close to the posterior end at the left of the lower part of the sulcus.
The ocellus is transversely oriented (fig. MM, /.). Of three species known,
all have at least 1.5 turns of the girdle and the sulcus exhibits an unusual degree
of torsion. In N. partitum there are at least 1.5 turns of this structure, of
which only about 0.5 is intercingular, the remainder constituting the anterior
and posterior loops, while in N. torpedo there are two turns. This anterior
loop may be present in other highly specialized Pouchetiidae as in Pouchetia
violaceum and in several species of Hrythropsis. Specialization in their funda-
mental structures such as the girdle and sulcus is thus accompanied by special-
ization elsewhere in the organism, as in the nematocysts of Nematodinium and
tentacle of Hrythropsis, not to mention the ocellus of these genera and of
Pouchetia.

422 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

We find in Nematodinium the same types of ocellus which have appeared
in other genera of the Pouchetiidae, in Protopsis, Pouchetia, and Erythropsis.
These two types have been utilized by us to distinguish subgenera in the last
two genera. However, in view of the small number of species as yet known
in Nematodinium, no subgenera are here established therein, although the same
basis exists therefor.

Kny To Species oF Nematodinium

1. Ocellus distributed, numerous small spheroidal lenses, melanosome diffuse —
partitum sp. noy.

1. Océllus comcentraitie dcx. sx See ae a a 2
2. Lens spherical, melanosome subhemispherical ~_...............-.-..-...----------------- armatum (Dogiel)
2. Lens elongated, melanosome very small, band-shaped — torpedo sp. noy.

Fig. NN. Nematodinium gen. nov. 1. N. armatum Dogiel). 2. Second individual of the same species.
3. N. torpedo sp. nov. 4. N. partitum sp. nov. XX 500.

Nematodinium armatum Dogiel
Plate 11, figure 122; text figure NN, 1, 2

Pouchetia armata Dogiel (1906), pp. 36-88, 42, pl. 2, figs. 48, 49. Symmetry reversed in
drawing.

P. armata, Klebs (1912), p. 480.

P. armata, Cavers (1913), p. 183.

P. armata, Lebour (19176), p. 198.

P. armata, Chatton (1914), p. 435.

Dracnosts.—A medium sized species, body subellipsoidal, its length 1.55
transdiameters; girdle a descending left spiral of 1.5 turns, displaced 0.75 trans-
diameter; sulcus extending far on epicone and coiled distally around hypocone
with a total of 1.25 turns; ocellus far posterior, simple, lens spheroidal, pig-
ment mass subhemispherical, black; nematocysts grouped about the nucleus.
Length, 95-1002. Mediterranean; Plymouth Sound; Pacific at La Jolla, July,
August.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 423

Description.—The body is asymmetrically subellipsoidal, flattened on the twisted ventral
face between pores, more convex dorsally, tapering somewhat posteriorly. The epicone is larger
than the hypocone, with the apex broadly rounded and antapex button-shaped, encireled dorsally
by the distal end of the suleus. The anterior and posterior flagellar pores are located on opposite
faces due te the torsion of the body.

The girdle forms a descending left spiral of 1.5 turns. Its proximal end is 0.35 of the total
length of the body from the anterior end and its distal end 0.16 from the posterior end. Its
total displacement measured in the anteroposterior direction is 0.75—0.85 transdiameter or about
0.5 of the total length. The furrow is deeply impressed with prominent lips. The sulcus extends
from near the apex spirally in descending left spiral of 1.25 turns of a narrow groove. There
is only 0.5 turn in the intercingular region, the remaining 0.75 being mainly in a posterior curve
around the ‘‘dorsal’’ side beyond the emergence of the posterior flagellum. It is possible that
the dorsal part of this posterior region is not true suleus. The posterior part of the sulcus hes
in a deep ventral depression at the right side of the ocellus. It is also possible that there is
more of an anterior loop than appears in the figures. The anterior and posterior flagellar pores
are at the anterior and posterior junctions of suleus and girdle respectively. The transverse
flagellum traverses the whole length of the girdle.

The ocellus is located far posterior, on the left side of the distal end of the sulcus, but still
mainly within the intereingular region of that groove. This location appears more clearly in
the text figure than in the other figures (pl. 11, fig. 122, and text fig. NN, 2) from a slightly
different angle, owing largely to the deep ventral depression in which this part of the sulcus les.
The ocellus has a length of 0.5 transdiameter and its main axis is almost horizontal and is
directed ventrally. It is of the simple type with a spherical lens of several concentric laminae
of equal thickness of a pale lemon-yellow color. One face is slightly covered by the irregularly
hemispherical black pigment mass, half again as large as the lens. A lighter core without
noticeable color les in its center.

The most noteworthy feature of this animal is its nematocysts. These he in a group of eight
to eleven clustered near the nucleus and are all directed more or less anterodorsally. They
are greenish peg-shaped bodies, faintly capitate, from 14-22, in length and 3-4, in greatest
diameter. Kach shows within a faint coil, the introverted thread. The arrangement varies
somewhat in different individuals, but the general direction and location are similar in all. The
differences in size are similar to those found in Polykrikos, and seem to be correlated with
varying degrees of distinctness of the thread. This is an indication of stages in development
or age of these organs. There is no evidence in our material that they are derived from or
associated with any organism used as food, and they are not located in vacuoles.

The nucleus is spheroidal, about 1.5 transdiameters in diameter and is located in the anterior
half of the body. As binary fission approaches it becomes obliquely elongated or reniform, and
lies with its long axis about 70° from the major axis. It is filled with fine, parallel, moniliform,
chromatin threads which run spirally about the long axis.

A small pusule was noted at the anterior flagellar pore, and in one individual a very large
posterior pusule extended from the posterior flagellar pore up to the nucleus. These pusules
are filled with a pinkish fluid. No food balls were seen.

The color of this species has been found to be quite variable, possibly because of the results
of previous ingested food. Dogiel (1906) gives to his figure a pale ochraceous color, located in
chromatophore-like bodies. One individual seen by us had more of an amber-yellow tone, due
also to chromatophore-like bodies distributed near the surface, principally dorsally, while in
another the protoplasm was lavender grey with no trace of yellow or chromatophores. Minute
glaucous green granules fill the periphery as cytolysis approaches. Dogiel figures lines of black
pigment granules in the lower part of the hypocone below the girdle arranged as if along striae,
though no such structural differentiations were to be detected in the surface plasma. In one
case only did we find a detached pigment granule, and this lay anterior to the proximal end of
the girdle.

424 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Diwvenstons.—Length, 95-100; transdiameter, 60-63; diameter of nucleus,
dle; length of ocellus, 30+; of nematoevsts, 14-22z,

ActIivitiEs.—It is very active, rotating on its axis in anticlockwise direction
with occasional brief reversals, and circling, under the cover glass, in clockwise
circles. As it slows down the rotation ceases and the circles decrease in size
until their diameter is only one to two times the length of the body. No dis-
charge of the nematocysts has been noted either before or after cytolysis.

OcCURRENCE.—A number of individuals were seen in the plankton at La
Jolla, California, in July and August, 1917, but not recorded. Two were re-
corded from the hauls of a No. 25 silk net from 80 meters to the surface, 6 and
4 miles off La Jolla on July 20 and 27 respectively in surface temperatures of
20°5 C and 21°4 C respectively. A third was taken in a surface haul off the
pier at the laboratory on August 4 in surface temperature of 21°5 C,

Dogiel (1906) records it as very abundant in surface plankton at times at
Naples, Italy, during his investigations from May to the middle of July. Miss
Lebour reports it as common in water samples from Plymouth Sound, England,
in May and June in both free and encysted condition. These samples were
taken 2.5 miles offshore from the surface and from 5 and 7 fathoms.

Compartsons.—The most striking difference between Dogiel’s P. armata
and our material of this species is in size. Our material has a length of 95
and 100+, as determined by the measurement of two different individuals. His
magnification is given as 850. If true, his organism was only one-half the size
of ours, or 50#. A comparison of length, transdiameter, diameter of nucleus,
lengths of nematocysts and of ocellus of his figure with our own reveals the fact
that a/l these dimensions are but one-half those in our records, on the basis of
his recorded magnification of 850. However, he also uses a magnification of
425 for certain other figures. If this magnification is applied to his figure the
dimensions of the axis and organs noted above coincide almost exactly with
those of our specimens. We regard this as an indication that the magnification
given by him is probably an oversight and that the discrepancy in size may
not exist. Miss Lebour (1917b) gives neither figure nor dimensions of her
material. In proportions, girdle, sulcus, color, and number and arrangement
of nematocysts our specimens agree closely with Dogiel’s, except for the fact
that his figure has reversed symmetry with the torsion and girdle running in
the opposite direction to the normal and usual one. This appears to be due
to error in his having drawn the structures of the lower surface upon the upper
one. No case of critically determined, reversed symmetry is known to us in
the Dinoflagellata, and this error of reversal of symmetry is one easily made
in our experience.

This species shares with Nematodinium partitum the possession of nema-
toeysts which have not been found elsewhere in the family. They are of the
same type and size as in Polykrikos, although somewhat larger (10-15) in
this species than in N. partitum (6 to 8).

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 425

Its simple but concentrated ocellus, its nematocysts, and its considerable
degree of torsion all mark it as one of the most specialized species of the genus
and family.

Nematodinium partitum sp. nov.
Plate 6, figure 68; text figures P, 2; MM; NN, 4

DrtaGnosis.—A medium sized species, ovoidal, length 1.7 transdiameters,
girdle a descending left spiral of 1.25 turns, displaced 0.8 transdiameter, sulcus
with both apical and antapical loops, its torsion 1.75 turns, ocellus of distributed
type with numerous spherical lenses and diffuse black melanosome, situated
far posteriorly; numerous nematocysts radiating from center. Length, 91+.

)

Pacifie off La Jolla, California, June, July.

‘DescripTION.—The body is ovoidal with the broadest diameter slightly anterior to the equa-
torial region. The epicone and hypocone are subequal. The epicone is broadly rounded at the
apex with a length above the anterior flagellar pore of 0.3 and distally on the right of the sulcus
of 0.8 of the total length of the body. The hypocone is abruptly truneate at the right, is longer
on the left side and broadly rounded there. It is traversed dorsally by the tip of the sulcus
which sweeps around antapex in 0.66 of a turn and marks off a small, rounded terminal lobe.

The junction of the girdle and suleus occurs at a point 0.3 of the total length from the apex.
Tt curves around the body in a semicircle before taking a posterior direction, making 1.25 turns
before meeting the sulcus at a point 0.13 of the total length from the antapex. It lies in a deep
depression anteriorly, but less so distally. It is everywhere deeply impressed with overarching
lips. The anterior flagellar pore opens at its anterior junction with the suleus and the posterior
pore just beyond its posterior junction. The transverse flagellum traverses 0.25 the total length
of the girdle.

The suleus invades the epicone in a broad curve, sweeping around nearly 0.75 of a turn in
a deep trough which fades out distally. Below the anterior flagellar pore it describes 0.25
circumference in reaching its posterior junction with the girdle, beyond which it sweeps around
the dorsal side of the hypocone in nearly a complete (0.75) turn of the descending spiral. On
the dorsal side at this point the hypocone forms a deep, overhanging shelf on the proximal
border of the suleus, its distal border showing no perceptible protrusion.

The ocellus is situated below the distal end of the girdle and at the left of the sulcus and the
posterior flagellar pore and extends in a dorsoventral direction. Its length is about 0.8 trans-
diameter. It consists of a distributed lens and a black amoeboid melanosome. The lens is
composed of about fifteen to twenty greenish yellow, spheroidal, hyaline bodies packed in three
layers, embedding the bases of the lens, and extending in long granular strands around them is
the black pigment of the melanosome. Numerous black granules are scattered in rows along
the borders of the girdle and the suleus, especially posteriorly.

The nucleus is large, ellipsoidal, spherical, or pyriform and elongated posteriorly. It is
situated near and anterior to the anterior flagellar pore. Fine chromatin strands traverse if,
some in spiral directions. Its major and minor axes are 0.56 and 0.7 transdiameter in length
respectively.

No pusules were observed. The cytoplasm is clear and very finely granular. A number of
minute oil globules were present at the anterior end and a greater number in the posterior part.
Scattered through the cytoplasm are numerous (15-20) nematocysts, greenish yellow in color.
These are considerably smaller than those found in N. armatwm, having a length of 5-8» and a
width of 2-32. The majority take, in general, an anteroposterior direction. They are arranged
roughly in three groups: one in the anterior part, one near the central region, and the third

426 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

posteriorly. Situated somewhat posteriorly is a large food body in which is found a group of
radial rodlets radiating out from a common center and occupying apparently the center of the
food body. These vary from 8-10, in length and from 0.5-1y in width and are pale greenish
in color. The food mass consists of a small Gymnodinium, pale yellow in color. All evidence
of internal structure had disappeared, leaving only an ovoidal outline and a broad girdle to
distinguish it.

The color is a pale rose color distributed evenly throughout the eytoplasm near the periphery,
leaying the central mass almost colorless. The animal was enclosed in a thin transparent eyst
a little larger than the body and conformable to its contour.

Another eneysted form (fig. P, 2), referred to N. partitum because of its ocellus and short
rodhike bodies resembling nematocysts, was enclosed in a spheroidal, double-contoured, trans-
parent cyst of nearly spherical form. When first observed it had an inner membrane closely
applied to the spherical protoplasmic mass, but this later expanded somewhat irregularly till
it met the outer membrane. In addition to the ellipsoidal nucleus and typical ocellus the
enclosed protoplasmic sphere contained a yellow food ball and some scattered peg-shaped bodies,
interpreted as nematoeysts, the largest of which is about the size of the nematocysts of the
individual of normal form.

The presence of cysts and of food balls in both of the individuals of this species that we
have seen, and the abnormal (spherical) form of one of these, suggests that these may be
digestion cysts, and that the form and contour may be more or less profoundly modified in this
state. The individual upon which this description is based was, however, apparently normal in
all important details.

Nutriticn is undoubtedly holozoic and other species of Gymnodinioidae evidently fall victims
to the voracity of this marauder. It is obvious that the Gymnodiniwm within the food vacuole
is so large that its entrance into the cytoplasm of Nematodiniwm would severely stretch the
intercingular part of the suleus, close to which it lies, when it was ingested.

Dimenstons.—Length, 91; transdiameter, 52; diameters of nucleus, 30-35
and 25--28#; length of nematocysts, 5-8.

OccURRENCE.—The individual figured was taken June 20, 1906, at La Jolla,
California, with a No. 20 silk net in haul from 37 meters to the surface.
Another encysted form was taken on July 9, 1917, with a No. 25 silk net in a
haul from 80 meters to the surface in a surface temperature of 19°2 C.

Comparisons.—This species is a trifle smaller than N. armatum, has more
numerous and smaller nematocysts, 54 to 84 as compared with 14 to 22H, and
a scattered ocellus instead of a concentrated one. The diffuseness of the ocellus
is noteworthy as compared with the Pouchetiidae as a whole. No species of
the family has more diffuse lenses and few exceed it in the diffuseness of its
melanosome. The optical efficiency of the ocellus of this species judged by its
position, multiplicity of lenses, and lack of codrdination of these with the pig-
ment must be of a low order.

Nematodinium torpedo sp. nov.
Plate 11, figure 124; text figure NN, 3
Diacnosis.—A large species with elongate fusiform body, its length 2.9

transdiameters; girdle a descending left spiral of 2.25 turns; suleus with nearly
2 turns, extending almost from apex to antapex; ocellus posteriorly located,

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 427

transverse, simple, with elongated lens, and small black melanosome; about 30
nematocysts grouped anteriorly. Length, 84". Pacifie off La Jolla, California,
August.

Description.—A remarkably specialized species with symmetrically fusiform body widest
at the middle and tapering equally towards the two ends, with slightly convex contours between
the furrows which notch its margins four times on either side. Its length is 2.9 its greatest
diameter. The epicone and hypocone are subequal in size and volume. Each extends within
0.3 transdiameter of the end opposite to itself owing to the extreme torsion of the body. The
apex is bluntly rounded, almost hemispherical in form, while the antapex is asymmetrically
rounded, being longer on its left, as a result of the asymmetrical dislocation of the posterior
end of the sulcus to the left.

The girdle forms a descending left spiral of 2.25 turns, growing steeper as it passes posteriorly
from 5° at its proximal end to 50° at its distal junction with the suleus. The interval of
posterior displacement of the second turn is five times that of the first and the total distance of
vertical displacement is 2.25 transdiameters of 0.78 total length. The furrow is deeply impressed
with an overarching anterior lip. The suleus makes nearly two complete turns. It extends
anteriorly above the girdle towards the apex for 0.5 the distance, descends from its junction
with the proximal end of the girdle in an ever steepening spiral to its posterior junction with
the girdle within 0.3 transdiameter of the antapex. It is continued thence, not in a posterior
course as usual in the Pouchetiidae, but in a continuation of the spiral which makes another
0.5 turn or more around the antapex beyond the posterior flagellar pore. This extension is
indistinct. The transverse flagellum traverses, in the moribund state, only the anterior part of
the girdle. The posterior flagellum arises from the pore at the posterior junction of girdle and
suleus and extends directly posteriorly, not in the spiral continuation of the suleus around to
the opposite side of the body.

The ocellus is 0.25 of the total length from the antapex, at the left of the posterior part of
the intercingular sulcus, lies transversely and is directed to the left with its outer end somewhat
protuberant. Its length is 0.6 transdiameter. It consists of an elongated, transparent, glaucous-
blue lens with eight cupped lamellae and a very small, curved, bandike melanosome across its
adsuleal end. Its constituent parts are more correctly represented in figure NN, 3, than in the
colored figure (pl. 11, fig. 124). No distinct colored core was detected.

The nematocysts are about thirty in number, arranged in two irregular circles around the
anterior third of the body peripheral to the nucleus. They are all pointed anteriorly. They
are yellowish green in color and in form are peg-shaped structures, 0.16—-0.25 transdiameter in
length, and their length is 2.5 to 4 times their greatest diameter which is anterior. There was
no nuchal constriction delimiting a capitate end. The interior of the capsule is fluid-filled and
contains the introvert consisting of the shaft and its spiral continuation coiled about it. On
cytolysis of the body the nematocyst is discharged and forms a flat close spiral a httle longer
than the capsule.

The nucleus is elongated ellipsoidal, its major and minor axes being 0.9 and 0.5 transdiameter
respectively in length. Its major axis coincides with that of the body. It les just anterior to
the middle of the body. No pusules were noted. Behind it is a spherical food vacuole containing
an ochraceous food ball with two dark ochraceous chromatophores. A black spherical pigment
grain lies near the apex and seattered about it are some smaller greenish oil globules, while larger
highly refractive globules presumably of an oily nature le near the antapex. The general color
of the plasma is an exceedingly transparent, pale glaucous blue.

Dimenstons.—Length, 83; greatest transdiameter, 29+; length of nucleus,
28; of ocellus, 18+; of nematocysts, 5-8.

rs
bo
oo

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

OccURRENCE.—One individual taken in a haul of a No. 20 silk net in haul
No. 1395, June 24, 1907, from 100 meters to the surface 2 miles off La Jolla,
California, in latitude 32° 53/1 N, 117° 17'3 W, in surface temperature of about
16°5 C.

ComMPaARISONS.—This species is built for rapid locomotion, as shown by its
shape and its furrows. Its nematocysts are small as in N. partitum, and it
shares with the other species in the genus the posterior location and transverse
direction of the ocellus, the continuation of the spiral course of the sulcus be-
yond the posterior flagellar pore on to the dorsal side of the antapex, and the
clustering of the nematocysts about the nucleus. It is highly specialized in
form, in grouping of the nematocysts and integration of the lens.

CHAPTER XIX

POUCHETIIDAE: POUCHETIA

POUCHETIA Schiitt emend.
Text figures OO-QQ

Pouchetia Schiitt (1895), in part, pp. 168-170, pl. 26, figs. 92, 94; pl. 27
(1896), p. 6, fig. 8.

Gymnodinium, Pouchet (1885a), in part, pp. 38-39, 85, pl. 2, fig. 1; (1885b), pp. 529-
531, 534, pl. 3, fig. 4; (1887), pp. 96-97, 112, pl. 10, fig. 1.

Pouchetia, Delage and Herouard (1896), in part?, p. 384, fig. 668.

Pouchetia, Paulsen (1908), in part, pp. 105-106, figs. 146, 148.

Pruchetia, Lohmann (1908), p. 369. Lapsus.

figs. 97-99 ;

DIAGNOSIS

Pouchetiidae with an ocellus located at the left of the intercingular sulcus;
no posterior prod; girdle a descending left spiral of 1.15 to 2 turns; sulcus with
torsion of 0.25 to 1.75 turns of a descending left spiral, its apical loop with
from 0 to 1.5 turns, and its antapical loop sometimes attaining 1 turn. No
paracingular lines. Ocellus with red or black pigment mass with red, brown,
yellow, or colorless central core; lens hyaline, laminate, or of appressed parts
or segments. Nucleus usually anterior to ocellus; perinuclear membrane rarely
present; moniliform chromatin threads distinct. Pusules, if present, opening
anteriorly into the anterior flagellar pore or posteriorly into the posterior. No
nematocysts; surface striae rarely present; plasma generally highly colored;
scattered melanin or other pigment granules sometimes present. Holozoic
nutrition; encystment in thin-walled membrane frequent. Length, 32-141,.
All marine, eupelagic and from warm temperate or tropical seas; 20 species
known.

ORGANOLOGY

Pouchetia has about as much torsion of the body as Cochlodinium, but with
this marked difference, namely, that the sulcus above the proximal and below
the distal ends of the girdle is itself continued in a spiral course which may
equal or even exceed the amount of torsion within the intercingular part of
that organ, whereas in Cochlodinium the torsion is mainly in the intercingular
region and the apical and antapical loops are never extended to the amount of
so much as 0.5 turn. In Pouchetia, on the other hand, either or both of these
loops may make as much as a full turn about the body, as for example in P.
violescens (fig. OO, 1). The apical loop may even make as much as 1.5 turns,
as in the species cited. When, however, the girdle of Pouchetia has two full

[429]

430 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

turns, as in P. purpurescens (pl. 8, fig. 84) and P. fusus (fig. PP, 1), these
terminal loops of the sulcus are lacking and the ends of the sulcus have little
or no torsion, thus resembling Cochlodinium.

The length and torsion of the suleus are intimately correlated with the
leneth, proportions, and constriction of the body, and the terminal loops tend
to increase the asymmetry of the species of this genus as compared with more
symmetrical species of Cochlodinium (cf. figs. GG@ and OO).

The presence of an antapical loop encircling the antapex below the point of
emergence of the posterior longitudinal flagellum accentuates the asymmetry
of the antapical region (see P. maculata, pl. 11, fig. 119), and provides the basis
for a progressive mobility of this region within Pouchetia, which renders this
territory very difficult to examine and portray adequately and correctly. It
also affords the earlier stages in the evolution of the remarkably active and
extraordinay prod, or tentacle, of Proterythropsis and Erythropsis.

It seems probable that the apical loop performs a like function for the apex,
which in Erythropsis is invaded by the anterior end of the sulcus and is some-
what labile. In P. violescens, P. juno, and P. atra (figs. OO, 1,3; PP, 5) modi-
fications of the apical region are brought about by this apical loop of the sulcus.

The ocellus in Pouchetia has all stages in the integrative process of com-
bining scattered pigment spherules into a compact mass enveloping the base
of the lens, and in a correlated combination of separate hyaline spheres into a
spheroidal laminate lens.

This process is clearly one of integration. The evidence for this conclusion
lies in the fact that those species (subgenus Pouchetia) with the diffuse non-
integrated type of ocellus, such as P. alba (fig. PP, 8), P. poucheti (fig. PP, 4),
P. schuetti (fig. PP, 10), and P. purpurate (fig. PP, 3), are not highly special-
ized in other structural features. They are nearer to Gymnodinium and Coch-
lodinium than are the species with the integrated ocellus. They have less torsion
in the girdle and sulcus, and both P. alba and P. poucheti are almost colorless
(pl. 11, figs. 121, 125), being lightly tinged with yellow and blue respectively,
while P. schuetti and P. purpurata with a more concentrated type of ocellus
reach the red end of the spectrum. P. fusus is yellow, has the Cochlodiniwm
type of torsion, without terminal loops in the sulcus, and its ocellus has a unique
ringlike melanosome binding together a bipolar lens.

The group of species (subgenus Pouchetiella) with more highly integrated
lens and melanosome also has within it various stages in the later phases of the
integrative process. In fact the distinctions between the two groups are not
clearly defined. The highest stage of integration results in a spheroidal lens
with concentric laminae, with one face buried in a black pigment mass or
melanosome which is also spheroidal or hemispheriodal and contains within its
center, in contact with the surface of the lens, a highly colored sensory (?) core.
Such ocelli are to be found in the highly specialized species such as P. juno,
P. violescens, P. maxima, and P. striata (fig. OO). They are usually median
in position and have their axes horizontal or 45° from the horizontal and directed

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 431

to the left anteroventrally or anterosinistrally. They are thus by structure
and position more highly specialized for their function than the looser aggre-
gates of the more primitive species of Pouchetia, and than the less integrated
ocelli of Pouchetiella, such as P. maculata and P. voracis (figs. PP, 12,2). In
these less integrated types the ocellus is usually farther posterior, smaller, both
relatively and absolutely, and may have an elongated lens more or less lobed
or transversely laminated as in P. voracis (fig. PP, 2), P. atra, and P. maculata
(pl. 11, figs. 126 and 119).

Fig. PP. Pouchetia Schiitt and Proterythropsis gen. nov. 1. Pouchetia fusus Schitt. After Schutt (1895,
pl. 26, fig. 94,). 2. P. voracis sp. nov. 3. P. purpurata sp. nov. 4. P. poucheti sp. nov. 5. P. atra sp. nov. 6.
P. parva Lohmann. After Lohmann (1908, pl. 17, fig. 23). 7. P. panamensis Kofoid. After Kofoid (1907,
pl. 1, fig. 7). 8. P. alba sp. nov. 9. Proterythropsis crassicaudata sp. nov. 10, 11. Pouchetia schuetti (Schutt).
After Schitt (1895, pl. 26, figs. 92, ,,). 12. P. maculata sp. nov. X 500.

The nucleus of Pouchetia always has distinct beaded, chromatin threads and
has not been found with the perinuclear membrane surrounding a hyaline area
about the regular nuclear contents. It is usually located anterior to the ocellus.
The exception to this relation, seen in P. compacta (fig. PP, 9), as oriented by
Schiitt (1895), may be due to an incorrect interpretation as to the anterior
and posterior ends of the organism.

432 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The genus Pouchetia shares with Cochlodinium the relative freedom from
longitudinal striae upon the surface of the body. These striae are common in
Gyrodinium and Gymnodinium, but are not associated in Pouchetia with primi-
tive or generalized species. Only three species have striae, P. striata, P. vio-
lescens, and P. maxima (figs. OO, 8, 1, 2), all highly specialized forms. Sug-
gestions of an underlying but ordinarily invisible linear organization of the
cytoplasm appear in the faintly linear grouping of pigment granules in P.
maculata (pl. 11, fig. 119), and the linear aggregates of pigment in P. violescens
(pe hess).

The color of the cytoplasm in Pouchetia is remarkably diversified, change-
able in tone and in aggregation, and probably subject to considerable modifi-
cations as a result of internal physiological states and stages of metabolism
(cf. figs. 118, 120, pl. 11). It may be diffuse as in P. rubescens (pl. 8, fig. 90),
P. purpurescens (fig. 84), P. purpurata (fig. 87), and P. voracis (fig. 89); or
in spheroidal aggregates as in the black granules of P. maculata, or the greenish
flecks of P. pouchett.

Nearly the whole range of colors of the spectrum is to be found within the
species of this genus, but most of them near the red end. P. violescens (pl. 11,
fig. 118), P. juno, and P. maxima (pl. 6, fig. 61) lie near the violet end, exhib-
iting tones of violet and lavender. P. poucheti (pl. 11, fig. 125) is bluish green,
P. atra (fig. 126) somewhat greenish, P. alba (fig. 121) faintly tinged with pale
vellow, P. fusus and P. parva are ochraceous, and the remaining twelve species
exhibit various shades of red, grading from the darker purples of P. purpurata
and P. purpurescens to the rosy tint of P. voracis. While there is no exact and
uniformly graded parallelism between the colors of the species of Pouchetia
arranged in the scale of the spectrum from violet to red and the progressive
structural specialization of these species, there is, nevertheless, a sufficient dif-
ference to justify the conclusion that pigment formation is a feature of pro-
gressive specialization in these organisms, passing from the faintly tinged bluish
green to the red and black colors, and that this is accompanied by structural
specializations of the ocellus, sulcus, and girdle. The evidence is as follows:
(1) the simplest species with least integrated ocellus and most Gymnodinium-
like furrows, P. alba and P. poucheti are faintly tinged with bluish green and
yellow; (2) all the rose-red species, P. compacta, P. panamensis, P. polyphemus,
P. rosea (Pouchet), P. rubescens, P. striata, P. subnigra, and P. voracis, and
the reddish-black P. maculata have well integrated ocelli, and a high degree of
complexity of girdle and sulcus. The two ochraceous species, P. fusus and
P. parva, are less specialized. There remains a group of purplish species, P.
purpurata, P. purpurescens, and P. schuetti. The first two of these are highly
specialized, the last less so. The two violet-lavender species, P. violescens and
P. juno, are highly specialized large species, and as such do not exhibit the
simplicity in structures shown in the general trend of the genus at the violet
end of the spectrum. The preponderance of evidence, however, suggests a

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 433

Schitt (1895, pl. 37, fig. 99,). 4. P. rosea (Pouchet). After Pouchet (1885b, pl. 26, fig. 1). 5. P. rubescens
sp. nov. 6. P. subnigra sp. nov. 7. P. purpurescens sp. nov. 8. P. striata sp. nov.
After Schiitt (1895, pl. 27, fig. 97,). 10. The same. After Schiitt (1895, pl. 27, fig. 97.).
(Pouchet). After Pouchet (1885), pl. 26, fig. 3). > 500.

Fig. OO. Pouchetia Schitt. 1. P. violescens sp. nov. 2. P. maxima sp. nov. 3. P. juno Schiitt. After

9. P. compacta Schitt.
11. P. polyphemus

434 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

correlation between pigment formation and structural specialization within the
genus Pouchetia.

Many if not all the species of this genus are holozoic in nutrition. The
evidence for this hes in the presence of food balls within food vacuoles in the
cytoplasm, the accumulations of the products of metabolism in the form of oil
globules, vacuoles, refractive rodlets and platysomes in the central or peripheral
plasma, and the presence of recognizable organisms within the food vacuoles
in a few cases. For example, P. voracis (fig. PP, 2) was found with the entire
theca of a species of Peridinium within it.

It is possible that the small P. parva is holophytic, but the only basis for
this conclusion is its ochraceous color. It is evident, however, that Lohmann’s
figure is quite diagrammatic and wholly inadequate to determine this matter.
There is no evidence that any of the other species have any chlorophyll or
xanthophyll of their own. The yellow bodies found within them appear in all
cases to be in food balls.

The intercingular sulcus is probably the mouth and it is not impossible that
the two pusules may represent remnants of areas of ingestion. The capture
of organisms and their ingestion have not been observed. The ejection of
undigested remnants has been watched in P. maxima. The antapex is rent
open, forming a protoplasmic skirt, and the fecal mass is extruded (pl. 6, fig. 61)
from its opening. The resulting modifications, which are temporary, are one
cause of the variability of the antapical region of this genus. It is also obvious
(fig. PP, 2) that the presence of large food masses may distort the contour or
even push aside ocellus and nucleus.

The wide prevalence of the formation of cysts in Pouchetia is correlated
with this holozoic nutrition. Individuals within cysts frequently exhibit food
balls or metabolic products (fig. P.) Such cysts are their digestion cysts
temporarily formed for a quiescent period of appropriation of a relatively
large volume of food. We have no evidence of binary fission within cysts in
Pouchetia.

The cyst forms as a pellicle on the surface of the plasma and is expanded
by the fluid accumulating within it by osmosis. The agency of the plasma,
especially along the sulcus, in this process is suggested by the more rapid dis-
tension of the membrane immediately over this organ.

DISTRIBUTION

Species of Pouchetia have been reported principally from warm temperate
and tropical seas and only from more northerly waters receiving warm currents
from these warmer regions. It is unfortunate that Schiitt’s monograph (1895)
gives no clue to the precise source of his species, P. compacta, P. fusus, P. juno,
and P. schuetti nom. sp. nov. (= P. rosea (Pouchet) Schiitt). They are pre-
sumably from the Bay of Naples or from collections of the Plankton Expedition
in the Atlantic. Pouchet’s material of P. polyphemus and P. rosea came from

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 435

Concarneau on the west coast of France within the influence of the Gulf Stream.
The same influence accounts for the more northerly records of Miss Lebour
(1917b) of P. fusus at Plymouth, England, and Pouchet’s isolated record of
P. polyphemus in Dyrefjord, Iceland, and probably also for the records of
P. rosea in the North Sea and Cattegat off the coasts of Denmark by Ostenfeld
(1913). On the other hand, P. parva, recorded thus far both by Lohmann
(1908, 1911) in the Baltic at Kiel and by Miss Lebour at Plymouth, may be
more of a northern and neritic species.

The only species recorded thus far from the Mediterranean are P. rosea
(Pouchet) by Pavillard (1905) at Cette and by Schroder (1900) from Naples.
The latter record may be for P. schuetti. The only species thus far reported
from the Pacific is P. panamensis by Kofoid (1907a) from the Bay of Panama.

To this single record for the Pacific we add in this paper from the plankton
off San Diego and La Jolla, California, the following species previously de-
seribed: P. rosea (Pouchet), P. juno Schitt; and twelve new ones as follows:
P. alba, P. atra, P. maculata, P. maxima, P. poucheti, P. purpurescens, P. pur-
purata, P. rubescens, P. striata, P. subnigra, P. violescens, and P. voracis.

HistrortcaL Discussion

This genus was established by Schtitt (1895), who figured P. compacta
(called P. contorta in his explanation of plates), P. fusus, P. juno, and P. rosea
(Pouchet). His P. rosea is, however, not Pouchet’s Gymnodinium polyphemus
var. roseum (1887, pl. 10, fig. 1), but a distinct species, P. schwetti nom. sp. nov.
He also figured P. cochlea and P. cornuta, both of which belong to Hrythropsis.
He later (1896) characterized the genus Pouchetia and established P. fusus as
its type (monotypic). Pouchet in a series of papers (1884, 1885a, 1885), 1886a,
1886), 1887) called attention repeatedly to the ocellate forms of the dinoflagel-
lates. His figures are usually very incomplete and inadequate and his con-
ception of the species he dealt with both inconstant and confused. He regarded
them all as species of Gymnodinium. This lack of precision is due in part to
the difficulties in working with these delicate organisms, their small numbers,
and to the newness of the field.

We regard his ‘‘Peridinium voisin de Gymnodinium spirale” (1885a, p. 89,
pl. 2, fig. 1) as a Pouchetia, but indeterminable until some one finds the species
again. His G. polyphemus (1885b, p. 534, pl. 26, fig. 3) is a Pouchetia, but
different from his G. polyphemus var. roscum (1887, pl. 10, fig. 1), which is
P. rosea (Pouchet), but not P. rosea (Pouchet) Schutt (1895), which is P.
schuetti nom. sp. nov. His G. polyphemus var. nigrum (1887, pl. 10, fig. 2),
which Lemmermann (1899) placed in Pouchetia, we transfer to the new genus
Protopsis. In 1907 Wright added P. ochrea to the genus. This we transfer to
Protopsis. In the same year Kofoid deseribed P. panamensis, and in 1911
Lohmann added P. parva, which by a slip of pen became (1911, p. 369) Pou-
chetia paron. The same author earlier (1908, p. 152) introduced a nomen

436 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

nudum, Pouchetia baltica. In 1906 Dogiel described P. armata, a species with
nematocysts. This we transfer to Nematodinium gen. noy. Dogiel also by
erroneous citation adds Gymnodinium polyphemus var. magna to the nomina
nuda referable to Pouchetia.

Our emendations to the genus exclude from it those species without torsion
(Pouchetia nigra (Pouchet) Lemmermann and P. ochrea Wright). These we
place in Protopsis gen. nov. We also exclude all ocellate types with paradinial
lines and posterior prod (Pouchetia cornuta and P. cochlea of Schiitt, 1895)
which belong in Hrythropsis, and one new ocellate species without paradinial
lines and with rudimentary prod which is the type species (crassicaudata) of a
new genus Proterythropsis. All ocellate species with nematocysts we place in
Nematodinium gen. nov. This transfers Dogiel’s (1906) Pouchetia armata to
Nematodinium, to which we add two new ocellate species, N. partitum and N.
torpedo.

To the residue of six previously described species remaining in Pouchetia,
to wit, P. fusus Schutt, P. compacta Schutt, P. juno Schiitt, P. panamensis
Kofoid, P. polyphemus (Pouchet) emend., P. rosea (Pouchet) emend., we add
twelve new species from the plankton of the Pacific off La Jolla, California,
as follows: P. alba, P. atra, P. maculata, P. maxima, P. poucheti, P. purpu-
rescens, P. purpurata, P. rubescens, P. striata, P. subnigra, P. violescens, and
P. voracis, and a thirteenth, P. schuetti nom. sp. noy., based on Schiitt’s (1895)
figures of P. rosea (Pouchet).

SUBGENERA OF Pouchetia
Subgenus 1. Pouchetia subgen. nov.

Ocellus not concentrated or integrated; lens in two or more parts, scattered
or arranged in one row; melanosome in the form of a diffuse network of scat-
tered disconnected spherules. Type, P. fusus Schutt. This subgenus includes
besides the type, P. alba sp. nov., P. poucheti sp. nov., P. purpurata sp. nov.,
and P. schuetti nom. sp. noy.

Subgenus 2. Pouchetiella subgen. nov.

Ocellus integrated ; lens spheroidal, laminate, or composed of closely applied
segments and elongated, massive melanosome, not sending out stout pseudo-
podia and not parted into spherules, closely applied to the base of the lens and
usually containing a red or brown sensory core. Type species, P. violescens.
This subgenus contains in addition to the type the following species: P. atra
sp. nov., P. compacta Schitt, P. juno Schutt, P. maculata, P. maxima sp. nov.,
P. panamensis Kofoid, P. parva Lohman, P. polyphemus (Pouchet), P. purpur-
rescens sp. nov., P. rosea (Pouchet) emend., P. rubescens sp. nov., P. striata
sp. nov., P. subnigra sp. nov., and P. voracis sp. nov.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 437

KKny TO THE Spectes oF Pouchetia

1. Ocellus diffuse, pigment scattered or amoeboid, lens in several pieces (subgenus
POUL CH E122) eremeenre eee ee tes ser ae Ace aR oe ee Rares eles BOE ery Pe ct be Se 2
1. Ocellus integrated, pigment mass compact, lens single (subgenus Pouchetiella) —.. 3
Ze Velanosomenring-shapedsslenss D1p Olay sees eee ene eeene ne eee fusus Schiitt _.
Zep VelANOSOMeRMO UELINO-St Ap CCl stn wre a mee er sees eka URE Sry 5S eee Sher. 4
AL, TEASED, TRACI GUEST AY oe2 PoE OAS Ma Se ak ee eee ee ee ee 5
Ae eLASH Aw OLECOISH LOLs Vell] Ow aS lime eee eee ete, eee tne we ate ees ee ees enact ca PN ee es 6
5. Plasma rosy, antapical region not contracted, torsion 0.25 turn schuetti nom. sp. nov.
5. Plasma purplish, antapical region contracted, torsion 0.50 turn ........ purpurata sp. noy.
6. Plasma pale yellowish, ocellus posterior, body wider posteriorly — alba sp. nov.
6. Plasma bluish green, ocellus median, body ellipsoidal — poucheti sp. nov.
3h JENarenaalh TSS) TRO, TOY Cre ENON ee rosea (Pouchet) emend
ee a NT Nig nUAS Saye talent O LEM O Tam scsi in e eaTa a peeeses eee ee ee ene eens Sv ae (
7. Large species, over 100, in length, ocellus median, horizontal 20222 8
7. Less than 100, in length, ocellus posterior, or if median not horizontal 2... 9
8. No long apical loop of suleus, faint striae posteriorly, plasma lavender_..maxima sp. nov.
{oh toP aN OpCGFall ed Kao a) CONE MEN Ge LYSE) Pad MAG PU a et eee eA OE Ts ROE ere Se 10
Om cellispbaresanterl 0 rp eos te eee oe ee ee heres! Sees ge een. on compacta Schiitt
Ome Ocell issn Cte pGenl Cd aie sae Atte Oe ne weenie) ess ENT oe ee pA Nae ee eee ee 11
10. Apical loop of 1.5 turns, surface with longitudinal striae, plasma violet
EEE RS oR ne oy PO SRN ar EEE MS ei PO Se ey dee ek ee oa he BS violescens sp. nov.
10. Apical loop of 1 turn, surface with rounded platysomes, no striae ............. juno Schiitt
HP evongitudimallstriaespresents: bodys rounds. ee ees striata sp. nov.
HOI MIN Op] OTN UG Ts TL ABS G11 Le wpe ee eres cr eae eR ee Pe eC Pe gee en ee Se 12
12. Length more than 2 transdiameters, large species —......... polyphemus (Pouchet) emend.
PAN eno thet essmt hails ditt AM SC cin © GETS pee see ee eae ae ee es ee 13
SaaS cael este eles sel esc lerame () pesmra Wi] ey7 cr ]a pes meres se estar nese ne nue Se ps us een pee 14
tS aalen cine One mt a are 0) iis en seen eee ee eee ee eee Sy ee ee orn oe ee 15
Ugh, DEM eevsy aay, TRCN eee ee eo ree ERE Ae a LR ie a a ee panamensis Kofoid
Ar ASTH ee OCIA COO US tree cetera ee etree ern a ye eee Pea parva Lohmann
15. Apical loop of 1.5 turns, ocellus far posterior atra sp. nov.
15. Apical loop, if present, with less than 1.5 turns, ocellus not at postmargin 0... 16
16. Girdle displaced at least 0.75 total length of body —. 0. purpurescens sp. nov.
Gm Cindlemdisplacedmless: thanw Oe totalelem ctl se -eesssses este see eee ee Sen nen sce 17
17. Length more than 1.5 transdiameters, lens elongated, granular black pigment strands ....
Se Bo ER tho ee eee DERE EEE aE eee er eee eee Te subnigra sp. noy.
17. Length not more than 1.5 transdiameter, pigment not in amoeboid strands —........ 18
ibis), ID MRR: TRISHA joeeacaVeroyh Galata ledeKoyHNH [aVO\Ohie Se cence a ge ea ee cee Se Oe coe ee pc eee 19
18. Black pigment scattered in peripheral spherules — 0.000020 maculata sp. nov.
19. Ocellus median, displacement more than 0.5 length of body 0.000000... voracis sp. nov.

)
. Ocellus posterior, displacement less than 0.5 length of body

seen Sores rubescens sp. nov.

438 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Pouchetia alba sp. noy.
Plate-11, figure 121; text figure PP, 8

DIAGNosis.—Small species with ovoidal body, enlarged posteriorly, its length
1.3 transdiameters; girdle 1.5 turns around body, displaced about 0.6 total length
of body; torsion 0.5 circumference; ocellus irregular, compound, situated far
posteriorly; lens double; amoeboid melanosome and scattered black pigment.
Length, 454. Pacific off La Jolla, California, July.

DescriprioN.—The body is small, oyoidal with the longest transdiameter posterior to the
middle of the body and nearly circular in cross-section. The epicone is somewhat smaller than
the hypocone, is symmetrically rounded near the apex, and has a length of about 0.3 of the
total length of the body on the left and of about 0.88 on the right side of the suleus. The
hypocone is broadly rounded, flattened on the antapex and deeply excavated on the ventral side
by the posterior end of the suleus.

The girdle joins the suleus at a point distant from the apex 0.3 of the length of body, sweeps
around the body posteriorly 1.5 times and joins the suleus distally 0.2 of the total length from
the antapex. The anterior flagellar pore is found at the proximal junction of the girdle and
suleus, and the posterior flagellar pore slightly beyond the distal junction on the opposite face
of the body from the anterior pore. The transverse flagellum traverses nearly the whole length
of the girdle.

The suleus begins midway between the anterior flagellar pore and the apex without a
terminal loop, curves regularly around the body 0.5 its cireumference and is continued beyond
the posterior flagellar pore to near the antapex as a deep trough.

The ocellus is situated at the right of the distal end of the suleus and the posterior flagellar
pore, and is directed obliquely anteroventrally. It has a compound, colorless lens, composed of
two ovoidal masses of hyaline material with concentric lines only faintly indicated. It is crossed
by the distal end of the girdle. The lens is large, being 0.3 the total length of the body in length,
its cross-diameter being 0.3 its own length. The two component moieties are obliquely flattened
against each other. Adjacent to the base of the lens is a small, spheroidal, denser part of the
black melanosome surrounding a very minute central core. Around this, partially covering
the posterior part of the lens and scattered through the distal third of the hypocone, is a loose
mass of black granules which exhibit amoeboid changes of position. A detached mass of black
pigment and several granules lie near the anterior flagellar pore.

The nucleus is situated in the epicone, an almost spherical body with a diameter of 0.7
transdiameter. Numerous chromatin strands traverse it in an anteroposterior direction.

The pusules were evident. The cytoplasm is finely granular and transparent, with few
alveoli or large granules present. Small greyish refractive bodies were situated in the epicone
with several large oil globules and greenish food vacuoles posteriorly. The surface of the body
lacks striae or other markings and there are no peripheral vacuoles. The color is a pale viridine
yellow diffused throughout the plasma.

Divenstons.—Length, 45-50"; transdiameter, 30-354; dorsoventral diame-
ter, 354: nucleus, 30.

Activitirs.—A normally active individual moves anticlockwise in large
circles, with rapid, shghtly jerking motions.

OccURRENCE.—T wo individuals were seen. These were taken in a No. 25
silk net in the Pacific Ocean off La Jolla, California, on July 12 and 17, 1917.
The hauls were made from a depth of 80 meters to the surface and in a surface
temperature of 20°5 C.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 439

Comparisons.—Pouchetia alba is the least differentiated member of the
subgenus Pouchetia. Its primitive stage of development is indicated by the
very slight coloration and its location in the yellow-green part of the spectrum,
by the slight torsion of the sulcus and relatively small amount of displacement
of the girdle. The intercingular region is equivalent to that found in the genus
Gyrodinium. The ocellus is also in the diffuse stage with little evidence of
functional and structural integration. The two segments of the lens are not
fused, the pigment mass is small in amount, scattered in amoeboid processes
away from the lens, is not applied closely to any large area of the lenses and
contains no red core. Neither the adjustment of lens and pigment nor the
location and direction of the axis of the ocellus are suggestive of functional
efficiency. In these particulars this species is most nearly approached by P.
poucheti (fig. PP, 4).

Pouchetia atra sp. nov.
Plate 11, figure 126; text figure PP, 5

DraGnosis.—Body ovoidal; length, 2 transdiameters; girdle a descending
left spiral of 1.6 turns, displaced nearly 1 transdiameter; suleus with apical
loop of 1.75 turns, its torsion 2 turns; ocellus posterior, concentrated; lens
elongate; black, amoeboid melanosome with red central core. Leneth, 64.
Pacific off La Jolla, California, July.

Drscription.—The body is rather slender, ovoidal with the widest diameter below the equa-
torial zone. It is deeply constricted by the girdle and the suleus. The epicone considerably
exceeds the hypocone. The length of the epicone above the anterior flagellar pore is 0.4, and
at its distal extremity 0.85 of the total length of the body. It contracts distally, its apex is
rounded, and its sides are deeply grooved by the suleus which makes 1.75 turns around it. The
hypocone is slightly broader than the epicone and has proximal and distal lengths of 0.6 and
0.15 respectively of the total length of the body. It is slightly asymmetrical and more convex
anteriorly. The antapex is asymmetrically rounded, being longer at the right. The suleus makes
but a shallow groove down the left face, ending at or near the antapex. There is no antapical
process and no suleal notch.

The junction of the suleus and girdle is located 0.4 of the total length of the body from the
apex. It sweeps around the body in a descending left spiral as a deep trough with bulging,
overhanging borders, making 1.6 turns before its posterior junction with the suleus 0.15 of the
total length from the antapex. The anterior flagellar pore opens at its anterior junction with
the suleus and the posterior flagellar pore at its posterior junction. The transverse flagellum
traverses 0.8 of its length.

The suleus takes origin near the apex and forms a descending left spiral of 1.75 turns before
reaching the anterior flagellar pore, beyond which it makes a sweeping curve to the right,
descends to the posterior junction with the girdle and thence posteriorly in almost a straight
line to the antapex. Its narrow channel is more deeply embedded anteriorly and on the left
face of the epicone than it is elsewhere, and especially toward the antapex.

The ocellus is relatively large and is situated at the extreme posterior end. It is at the left
of and behind the suleus, directed obliquely anterosinistrally about 45° from the main axis.
The lens is of the imperfectly concentrated type and shows a marked tendency toward the

440 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

diffuse, having the distal border imperfectly lobed and slender strands of granular pigment
distributed on the lens. It is elongated, 0.6 transdiameter in length, with a width of 0.5 its
own length. It is circular in cross-section and greenish blue at the distal end, changing to
yellow ochre towards the melanosome. Ventroposterior to the lens and partly embedding one
side of it is the melanosome. This is large, 0.3 transdiameter in length. It is composed of black
pigment with a red core. Streaming out from it are amoeboid strands of black granules, one
of which closely invests the right border of the lens, another passing over its dorsal face.

The nucleus is large, elongate reniform, and occupies the central area of the body with its
major axis longitudinal. Rather coarse strands of chromatin curve around its major axis, about
fourteen on one face. Its length is 1.1 and its width 0.5 transdiameters. A small, pink club-
shaped pusule opens at the anterior and another at the posterior flagellar pore.

The cytoplasm is rather coarsely granular with a few greenish oil droplets peripherally located
in the median and posterior regions. A large, blue-green food mass is found in the posterior
part near the ocellus.

The color is bluish green, diffused throughout the cytoplasm. The organism was enclosed
in a thin transparent cyst slightly larger than the body and conformable to its contour. An
unusual condition was noted in that a few bluish-green oil granules were present against the
inner surfaces of the cyst outside of the body. This species was found in both the encysted and
free state. The constrictions of girdle and suleus were deeper in the encysted stage and the
ventral arching more pronounced in the free state. The cyst wall was rather heavy and trans-
parent, adhered to the glass, and was rather closely applied in the two eysts observed.

Dimensions.—Length, 60-64; transdiameter, 25-32.5"; axes of nucleus, 36
(18) and 15 (10); length of lens, 19.

The unusual size of the nucleus figured was evidently due to the approach
of division, the other forms seen having a much smaller ellipsoidal nucleus, as
may be seen from the measurements in parentheses.

OccuRRENCE.—Three individuals were taken July 23, 1917, 6 miles off La
Jolla, California, with a No. 25 silk net in a haul from 80 meters to the surface
and in a surface temperature of 20°8 C.

Comparisons.—Pouchetia atra is on the borderline between the two sub-
genera Pouchetia with diffuse ocellus and Poucheticlla with the concentrated
type. Its melanosome is only slightly lobed and its amoeboid streamers are
feebly developed. The lens is also elongate and slightly lobed and not fully
integrated by location into a typical axial relation to the melanosome. This
lack of complete concentration it shares with certain other species with pos-
terior ocellus such as P. alba, P. maculata, and P. schuetti, and with several
species with median ocellus such as P. maxima, P. poucheti, and P. purpurata.
The ocellus is farther posterior in P. atra than in any other species and exhibits
one of the later steps in the evolutionary integration of this organ towards the
concentrated type. The ocellus in the free individual had a shghtlvy more
anterior position and had more of an anterior direction of its optical axis, much
as in P. purpurata. It is possible that the pressure of the food ball in the
individual figured (pl. 11, fig. 126) is responsible for the extreme posterior
position of its ocellus and for the discoloration of its lens.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 44]

Pouchetia compacta Schiitt
Text figures OO, 9, 10

Pouchetia compacta Schiitt (1895), pp. 96, 97 (pl. 27, figs. 97,_., by citation only).
P. contorta Sehtitt (1895), pp. 169, 170, pl. 27, fig. 97,_..
P. contorta, Lemmermann (1899), p. 360.

DraGnosis.—A large species; body very rotund, length 1.1 transdiameters;
girdle a descending left spiral of 1.5 (?) turns, displaced about 0.5 (?) trans-
diameter; sulcus with about 1.25 turns; ocellus anteroir, subhorizontal, concen-
trated, elongate lens (?), black, amoeboid melanosome ; rosy vacuoles. Length
91u, Plankton Expedition, Atlantic (?), or Bay of Naples.

Descriprion.—This is based on Schiitt’s (1895, pl. 27, figs. 97,,) figures, explanation of
figures and brief textual references. Body very rotund (probably much contracted), its longi-
tudinal axis only 0.1 greater than its transverse axis. The epicone is broadly rounded, somewhat
flattened at the apex, and deeply constricted at the left side. The hypocone is asymmetrically
rounded, the distal end of the suleus (?) deeply notching it on the left side. The sulcus is only.
faintly indicated in the second one of Schiitt’s figures (text fig. OO, 10), thus making uncertain
the definite measurements of regions related to that structure. From these indications the
anterior point of junction of the girdle and sulcus would seem to be just above and to the right
of the ocellus in the body. From that point it passes posteriorly over the notch in the melano-
some (text fig. OO, 10) and joins the girdle again distally at a point on the opposite face of the
body from that shown in the figure, then sweeps around the hypocone in the deep trough shown
in the lower part of text figure OO, 9, as the antapical loop. This seems to be the only possible
interpretation to be placed on the two figures given by Schiitt, and the description given here-
with is based on that assumption. If this be the true interpretation it makes the epicone consid-
erably smaller than the hypocone, with approximate lengths from the apex to the proximal and
to the distal extremities of the epicone of about 0.2 and 0.6 of the total length respectively.

The girdle begins apparently at a point just above the ocellus, passes around the body in a
horizontal semicircle before changing its course to a steep spiral in the dorsal side, flattening
again prior to its posterior connection with the suleus. It thus makes nearly 1.5 turns around
the body before meeting the girdle distally on the left face of the organism, with a total dis-
placement of about 0.5 transdiameter. It forms a broad, rather deep channel throughout its
course with the lips smooth and rounded. No pores or flagella have been figured.

The suleus takes origin near the apex with an apical loop of about 0.25 turn before its
junction with the girdle. It sweeps posteriorly as a deep trough (fig. OO, 10) for 0.5 turn
before joining the girdle distally, beyond which it sweeps around the dorsal face of the hypocone
as a deep trough for another 0.5 turn, ending close to the left side of the antapex.

The ocellus is situated less than 0.2 of the total length of the body from the apex on the
ventral side at the left of the suleus. Its axis is in part almost horizontal, but the lens is curved
posterosinistrally nearly 45°. In Schiitt’s first figure (fig. OO, 9), drawn from a fresh, living
cell, the ocellus is figured, and described in his explanation of plates, as having a elub-shaped,
black melanosome with a highly refractive sphere closely connected with it. Several black-
pigment masses are present near the border of the girdle and suleus. In his second figure of
the moribund ¢ell (fig. OO, 10) the melanosome is amoeboid and detached pigment masses are
more numerous. The lens is apparently disintegrating into spherules, the five rounded bodies
close beside the melanosome which he has designated as lens (Ls), describing them as highly
refractive spherules with a surrounding wall ‘‘Y-oil with plastid.’’ These are possibly oil
globules, and not the lens divided up into smaller moieties as he has designated them. The
presence of oil globules near the ocellus is a phenomenon of very frequent occurrence through-
out the whole genus. On the other hand, the whole evidence throughout the group points toward

442 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

the stability of the lens as an organ of definite outline and shape which does not break up into
smaller moieties except in late stages of actual cytolysis.

The nucleus is large, broadly ellipsoidal, situated just posterior to the ocellus and extending
nearly to the antapex. Moniliform chromatin threads are plainly evident. Its major and
minor axes are 0.6 and 0.4 transdiameter in length respectively.

No pusules have been figured by Schiitt. The protoplasm is finely granular with a marginal
zone which apparently covers most of the body, and consists of rodlets which are placed at right
angles to the surface. In cross-section these appear as circular in outline with a definite border
and central mass. In preparation fixed in osmic acid these rodlets are replaced by elongated
vacuoles which in a surface view appear as irregular openings, or a network, with meshes of
varying sizes, and all apparently much larger than the circles in the optical section from the
living specimen.

Seattered through the protoplasm are a number of rosy globules of varying sizes which he
designates as oil masses. These change their size easily, giving off part of their substance in
smaller droplets. Near the ocellus is a large, yellowish food mass. The coloring of the body is
evidently confined to the red oil globules, the protoplasm being left colorless, with no mention
made of it in his explanations.

Dimenstons.—Length, 914; transdiameter, 80“; major and minor axes of
the nucleus, 49 and 35 respectively; longest diameter of the ocellus, 30+.

OccURRENCE.—Figured by Schiitt (1895) in his Plankton Expedition mono-
graph, presumably from the Atlantic or Bay of Naples.

ComMParIsons.—Pouchetia compacta has the ocellus farther anterior than
any other species in the genus. In fact, it is located in the most anterior part
of the hypocone, immediately adjacent to the region of the anterior flagellar
pore. The nearest approach to it in this feature is found in P. polyphemus
(Pouchet), as oriented by us. The ocellus is clearly of the integrated type.
The extensive antapical loop of the sulcus beyond the probable location of the
posterior flagellar pore is not unlike that found in other large species, such as
P. violescens and P. juno.

In view of the fact that in Pouchetia generally (see text figs. OO and PP)
the nucleus lies anterior to the ocellus it is more than probable that Schttt’s
orientation (1895) is reversed and that the ocellus is posterior in P. compacta,
as it is in other species. We leave the orientation, however, as Schutt delineates
it, until the species is rediscovered when the orientation can be accurately
determined.

SynonyMy.—This species was figured by Schutt (1895, pl. 27, fig. 97:.) and
named Pouchetia contorta in his accompanying explanation of plates (pp. 169,
170). In text references (pp. 96, 97) he cites two of these figures (fig. 971-2)
as P. compacta, and on an earlier page (p. 85) cites the figures without quoting
the name of the species figured. The question might arise which is the valid
name under these circumstances. The name compacta on pages 96-97 has pri-
ority by position over contorta, on pages 169-170, unless it be held that the prior
citation, on page 85 of the figures without name, carries with it the explanation
of the figures on pages 169-170 with the name contorta assigned thereon to the
figures cited. It seems best to apply the law of priority by position literally
and to give compacta precedence over contorta.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 443

5 Pouchetia fusus Schiitt
Text figure PP, 1

Pouchetia fusus Sehiitt (1895), p. 96, pl. 26, fig. 94; (1896), p. 6, fig. 8.
P. fusus, Delage et Hérouard (1896), p. 384, fig. 668.
P. fusus, Lemmermann (1899), p. 360.
P. fusus, Cavers (1913), pp. 182, 183, fig. 9,,.
P. fusus, Lithe (1913), p. 230, fig. 230, ocellus lacking.
P. fusus, Lebour (19176), p. 198.

Dracnosis.—A medium sized species with fusiform body, its length 2.53
transdiameters; girdle a descending left spiral of 2 turns, displaced 1.33 trans-
diameters: suleus with 1 turn, without anterior and posterior loops; ocellus
premedian with bipolar lens and circular equatorial pigment mass. Length,
94. Bay of Naples or Atlantic (?); Plymouth Sound, England, September.

Derscription.—The body is stout fusiform, widest at the middle, more tapering posteriorly,
its length 2.33 transdiameters at the widest part. The epicone has a length at its left and right
sides of about 0.20 and 0.75 respectively of the total length of the body. It is thus a trifle
shorter than the hypocone, but being stouter anteriorly has about the same volume as the longer
hypocone. The anterior part is convex conical (55°) with rounded apex. The hypocone is more
tapering (50°), less rounded at the antapex and somewhat less symmetrical. The dorsoventral
and transverse diameters are equal.

The girdle begins at the anterior flagellar pore, located at its junction with the sulcus, about
0.2 total length of the body from the apex, forms a descending left spiral of almost two full
regular turns, with a total displacement of 1.33 transdiameters or 0.56 total length. The furrow
is deeply impressed and has a width of 0.14 transdiameter. The suleus begins a short distance
below the apex of the epicone, runs posteriorly to the junction with the girdle, and turns in a
descending left spiral for nearly a full turn to its posterior junction with the girdle, beyond
which it runs posteriorly nearly to the antapex in the median plane. There is thus neither an
anterior nor a posterior loop, and there is no suleal notch at the antapex. Both flagellar pores
are near the midventral line. The transverse flagellum makes more than one turn and the
longitudinal exceeds 0.5 of the length of the body.

The ocellus is peculiar in two respects: its location is deep in the eytoplasm almost in the
axis of the body anterior to the middle and to the greatest diameter, and it is bipolar. Its length
is about 0.65 transdiameter and its axis is almost parallel to, or coincident with, the axis of the
body (without torsion). The narrow intervals between the turns of the girdle and suleus do
not permit so large a lens to occupy the usual peripheral position at the immediate left of the
suleus. It thus appears to be forced into the interior by the torsion of the narrow body. It
consists of a bipolar lens with an encircling equatorial pigment mass. The exposed ends are
spheroidal, about 0.3 transdiameter in diameter, of equal size, with about 0.25 diameter covered
by the pigment mass. This is a ringlike structure, the diameter of which is 1.2 and the length
about 0.6 of that of a lens. It is black with a reddish brown center. Lebour (1917b) says it is
dark red and was seen breaking up into small red spots in one case. Except for a small globule
of black pigment on the posterior lip of the girdle on the dorsal side no other structures are
noted by Schiitt (1895).

Divenstons.—Length, 94; transdiameter, 41; length of ocellus, 27.

OccuRRENCE.—Figured by Schiitt (1895) from the collections of the Plank-
ton Expedition, presumably from the Bay of Naples or the Atlantic. The only
other record is that of Miss Lebour (1917), who reports it as rare in September
in the plankton from Plymouth Sound, England.

444 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

CoMPARISONS.—This species is unique in Pouchetia and in the whole family
Pouchetiidae in the structure of the ocellus. In shape of body it is near Nemat-
odinium torpedo. The straight course of the suleus on epicone and hypocone
above and below the girdle is scarcely equaled elsewhere in Pouchetia. It is
thus one of the most divergent species in that genus, although it becomes the
type species of the genus (by specification) and is the only one cited by Schiitt
(1896) when he characterized Pouchetia. Because of the compound lens we
place it in the subgenus Pouchetia.

Pouchetia juno Schiitt
Text figure OO, 3

Pouchetia juno Schiitt (1895), pp. 6, 87, 97, 170, pl. 27, figs. 98,., 99,»

P. juno, Lemmermann (1899), p. 360.

P. juno, Lang (1901), p. 161, fig. 175b.

P. nigra, Pavillard (1905), in part, p. 47, as a synonym (?) of P. nigra (Pouchet) Lem-
mermann (= Protopsis nigra (Pouchet) Kofoid and Swezy).

P. juno, Lithe (1913), p. 320, fig. 322 B.

Dracnosis.—A large species, body stout fusiform, constricted, its length 2
transdiameters; girdle a descending left spiral of 1.5 turns; sulcus with torsion
of 2.5 turns, with apical loop of 1.25 turns; ocellus concentrated, median, hori-
zontal; lens spheroidal; melanosome massive. Length, 141“. Atlantic, Pacific
off La Jolla, California, July.

DescriptioN.—The body is stout fusiform, its length 2-2.3 transdiameters measured at the
widest point which is about equatorial, deeply constricted by the suleus, and concave in outline
in the central section when fully elongated (Sehiitt, 1895, pl. 27, fig. 99,). The epicone is 0.4
of its own length longer than the hypocone. Its length at the proximal and distal ends of the
girdle is 0.30-0.43 and about 0.84 respectively of the total length of the body. It is rounded
subeonical at an angle of about 40°—50°, and the apex is flat or rounded and evidently much
modified by the terminal suleus. The hypocone has a length at the two ends of the girdle of
0.57-0.70 and 0.11 respectively of the total length of the body, and is more broadly subconical
(55°) with a truncate antapex notched by the distal end of the suleus.

The girdle forms a uniformly descending left spiral, 20°-25° from the horizontal. It joins
the suleus anteriorly at 0.30—0.43 total length from the anterior end and reunites with it distally
at about 0.11 of the total length from the postmargin, on the opposite side of the body from its
origin. It thus makes 1.5 turns and is displaced about 0.45—-0.60 total length. The furrow is
0.1 transdiameter in width and is very deeply sunken into the plasma, with prominent over-
hanging anterior lip.

The suleus runs from apex to antapex and has a total torsion of about 2.5 turns. Schiitt’s
two figures are irreconcilable as to the course of this structure. His first figure (1895, pl. 27,
fig. 98,) more correctly portrays the course and in our text figure (fig. OO, 3) we have repro-
duced his second figure modified to bring out the correct interpretation, especially with reference
to the posterior end of the suleus. The long channel (?) seen in the posterior part from which the
posterior flagellum seems to emerge may really have been the posterior pusule opening posteriorly
at the posterior flagellar pore and not the suleus seen through the body from above. We so
interpret it in our modified figure. The suleus has an apieal loop of 1-1.5 turns which may
surround a small apical eminence. The intercingular section makes about 1.2 turns crossing

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 445

the protuberant ocellus, flattening the spiral distally to 20° from the horizontal and turning
abruptly posteriorly at the posterior junction. The anterior flagellar pore is at the anterior
junction, and the posterior pore immediately at the posteroir junction of girdle and suleus.

The ocellus is slightly postmedian in location, at the left of the anterior part of the inter-
cingular suleus. Its length is 0.5 transdiameter and the lens is directed horizontally to the left
side of the body, on whose margin about 0.5 of the body of the lens protrudes. The ocellus
consists of a spheroidal lens about the same size as the melanosome and 0.33 transdiameter
across. It is hyaline, finely laminate and has a narrow peripheral layer strongly differentiated.
In encysted and moribund animals it becomes more ovoidal in form, with the larger end pro-
truding and the melanosome sends out short stout processes. In the normal condition the black
melanosome is a hemispheroidal or rounded mass in which one face of the lens is lightly imbedded.
No bright colored central core was noted. Small detached strands of brownish-black melanin
lie parallel to the girdle in its margins.

The nucleus is ellipsoidal, located anteriorly, and has about twenty beaded spiral chromatin
strands across one face. Its major and minor axes are 0.9 and 0.7 transdiameter in length
respectively. One or more long clavate pusules open anteriorly at the anterior flagellar pore
and what appears to be a long slender one passing anteriorly to the ocellus opens posteriorly
at the posterior pore. Irregular rounded double-contoured platysomes fill the peripheral plasma,
showing locally shght indications of near arrangement. There are also the faintest of sug-
gestions of linear striae in the pellicle which persists on plasmolysis (Sehiitt, 1895).

The color of this organism is neither figured nor stated by Schiitt. Our own observations
are restricted to a single individual recorded at the time in our notes as haying dark purplish
black granules along the girdle as cytolysis approached.

Dimenstons.—Length, 1254; transdiameter, 70“; length of ocellus, 214; of
nucleus, 32e and 22:.

OccURRENCE.—Ohe individual was taken July 3, 1906, 2.75 miles of La Jolla,
California, in a haul of a No. 20 net from 155 meters to the surface in a surface
temperature of 20°5 C,

Schiitt (1895) figures this species, presumably from the Bay of Naples or
from the collections of the Plankton Expedition in the Atlantic.

Compartsons.—Pouchetia juno is one of the most highly specialized species
of the subgenus Pouchetiella with integrated ocellus. Its specialization is indi-
cated in the spherical, laminate lens, compact melanosome, median location, and
horizontal position of the ocellus; also by the extreme torsion of the sulcus of
2.5 turns, its extent from apex to antapex, and the prolonged apical loop.

It is closely related to P. violescens, having the same type of ocellus, simi-
larly located, the same long apical loop, and about the same torsion of suleus.
It differs, apparently, in coloration, proportions of body, and in the course’ of
the apical loop, relative size of lens and melanosome, and striations. P. juno
has not been reported to be violet in color, is more fusiform, does not have the
apical loop crossing the apex, but encircling it only, has the lens much larger
than the pigment mass instead of equal to it, and has exceedingly faint stria-
tions instead of prominent ones. The possibility of both falling within the
range of one variable species is not excluded. More material is needed to de-
termine this with certainty.

446 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

SynonyMy.—Pavillard (1905, p. 47) cites it tentatively as a synonym of
Pouchetia nigra (Pouchet) Lemmermann (1899). This allocation seems to us
untenable since the course of the girdle and sulcus in the two species is wholly
different. Moreover, the ocellus of Protopsis nigra (Pouchet) Kofoid and
Swezy is of the diffuse type, while that of P. juno is an integrated one and
highly specialized. In addition Protopsis nigra is a small species, length 744,
while Pouchetia juno is a large one, 125-141» in length.

Pouchetia maculata sp. nov.
Plate 11, figure 119; text figures T, 2; PP, 12; QQ, 1

DraGnosis.—A small species, ovoidal, wider anteriorly, length 1.3 trans-
diameters; girdle a descending left spiral of 1.5 circumference; ocellus post-
median, horizontal, with segmented elongated lens and a black melanosome with
a lighter central core. Length, 53« to 58. Pacific off La Jolla, California,
July.

Descriprion.—The body is ovoidal, somewhat flattened laterally and contracting posteriorly,
irregular in outline owing to the projecting lobes between furrows on the ventral face. Its
widest diameter is found some distance above the middle of the body plane. The epicone and
hypocone are subequal. The epicone is very broadly rounded, having a length above the anterior
pore of 0.3 and from its posterior extremity of 0.8 of the total body length. The apex is flaring
hemispherical. The hypocone is very deeply cleft on the ventral side of the sulcus, the inter-
vening ridges of which may be more or less pronounced. The antapex is broadly rounded and
not cleft by the suleal notch. There is an antapical process, more or less pushed anteroventrally,
which lies at the right of the longitudinal flagellum. It is variable in form in different aspects
and differs in the two individuals under observation. It is probably somewhat mobile and may
represent the first step in the evolution of the tentacle as developed in Erythropsis. In one of
our specimens (pl. 11, fig. 119) it is a short rounded lobe projecting posteroventrally near the
ocellus at the right of the flagellum. Its diameter in an obliquely lateral view is a little more
than its length, which is 0.14 transdiameter. Its dorsoventral extension is thus not great
(fig. QQ, 2). On the other hand, this antapical process is more posterior in location, and has a
much greater extension as a long ridge or crest more than twice as long as it is wide or high.
It terminates abruptly on the dorsal and median faces. It is possible that there is a posterior
loop of the suleus around this process.

The girdle joins the suleus anteriorly at a point 0.3 and posteriorly 0.8 of the total length of
the body from the apex. It passes in a semicircle around the body before the descending left
spiral steepens sharply in its distal quadrant. It makes 1.5 turns before meeting the suleus
distally at a point about 0.2 of the total length of the body from the antapex. The total dis-
placement is 0.5 total length of body or 0.68 transdiameter. For most of its extent it is deeply
embedded, the proximal border forming an overhanging ridge. On the ventral side this becomes
more pronounced and is shown on both borders. The anterior flagellar pore is located at its
anterior and the posterior pore at its posterior junction with the suleus. The transverse
flagellum traverses 0.3 of its total length. The longitudinal flagellum equals or exceeds the
length of the body in length.

The suleus forms a sight loop around the right face of the epicone, taking its origin at the
left of the apex. It descends posteriorly, sweeping around nearly 0.5 of a turn before meeting
the girdle distally, beyond which it turns to the right as a very deep groove, the proximal border

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 447

of which forms a deeply overhanging lip. It is a shallow channel on the epicone, but becomes
more deeply embedded as it proceeds posteriorly. This, with the deeply embedded girdle, breaks
up the ventral face into three more or less projecting lips, the lower one of which may show a
greater protrusion.

The ocellus is large, about 0.4 transdiameter in length, located some distance below the
equatorial plane to the left of the sulcus. Its axis is horizontal and it is directed ventrally.
The lens is oblong in shape and is composed of four moieties closely joined together, of a clear
hyaline material and greenish in color, closely embedding its base in the large rotund, black,
amoeboid melanosome with its hghter central core. The ocellus is of the concentrated or simple
type, although the lamination of the lens still shows its origin from separate parts (pl. 11,
fig. 119). In two other individuals the lens (fig. QQ) was less elongated and less distinctly
segmented.

ar

Sl

Fig. QQ. Pouchetia maculata sp. nov. Two individuals showing variations in size and shape of lens and
in pigmentation. X 710.

The nucleus in both individuals figured has the elongated, enlarged, somewhat reniform
contour characteristic of predivision stages. Its major and minor axes are 0.6 and 0.4 trans-
diameter respectively. Fine beaded parallel chromatin strands follow its major axis. In what
is apparently the usual vegetative condition its major and minor axes are about 0.5 and 0.3
transdiameter respectively.

A small pink club-shaped pusule opens into the anterior flagellar pore. None was noted at
the posterior pore. The cytoplasm is clear and granular, but so filled with colored masses as to
give the whole body a dense appearance. In the half of the organism are a number, varying
from 2 to 6, of long, slender, green rodlets. These are generally placed at right angles to the
surface and point toward the center of the body. In the posterior region of the individual
figured in color (pl. 11, fig. 119) was located a large, rounded, reddish-brown food mass, and
many very small green rodlets apparently differmg in no way except in size from the larger
ones. These radial structures appear to be accumulations of substances along paths in which
substances in metabolism are in transit. Small green oil droplets are abundant near the surface.
The peripheral layer also contains, abundantly scattered over the entire surface, irregular or
spheroidal pigment masses of sooty black color. In one individual observed the peripheral
plasma was strewn with this pigment in the form of fine black rods, curved commas, S- and U-
shaped figures, and irregular short curves as well as in small grains. While under observation
these began to round up in spherules prior to cytolysis. The general color of the organism is
a bluish grey with a reddish-brownish tinge in one case in the posterior region, evidently due to
the solution of the adjacent food mass.

448 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Divenstons.—Length, 53-58; transdiameter, 37-44"; axes of nucleus,
19-35» and 10-184.

OccURRENCE.—T wo individuals were taken July 26, 1917, 2.5 miles off La
Jolla, California, with a No. 25 silk net in a haul from 80 meters to the surface
and in a surface temperature of 21°74 C. On July 23 another individual was
taken at approximately the same place and with the same 1e apparatus, the surface
temperature being 20°2 C.

ActTrvitIes.—One individual seen was still active and circled feebly on the
substrate in narrow, anticlockwise spirals with spasmodic jerks, due probably
to intermittent adhesions of the flagellar apparatus.

CoMPARISONS. alized member of the subgenus Pou-
chetiella, which has a concentrated or integrated ocellus. In the posterior
location of the ocellus, its horizontal axis, and the presence of an antapical lobe
or process, it is like Proterythropsis crassicaudata and also possesses in com-
mon with it distributed peripheral granules of pigment. In the latter species,
however, the pigment is red instead of black and is less abundant with more of
a linear distribution, the lens is more distinctly lobed, and the antapical process
much longer. The linear form of the distributed peripheral pigment is almost
identical with that in Protopsis nigra (Pouchet, 1887, pl. 10, fig. 2).

Pouchetia maxima sp. noy.
Plate 6, figure 61; text figure OO, 2

Diacnosis.—Large species, ellipsoidal, its length 1.4 transdiameters; girdle
forms a descending left spiral of 1.5 turns, displacement 0.72 total length; tor-
sion 0.75 turn, ocellus concentrated, median, horizontal; lens hemispherical,
melanosome with reddish brown central core; plasma pale lavender. Length,
145+, Pacific off La Jolla, California, July.

DeEscripTion.—The body is subellipsoidal with the dorsal side more convex, and the ventral
flattened. Its length is 1.4 transdiameters at the widest part of the body which is equatorial.
The epicone is shorter than the hypocone by 0.12 the length of the former, is asymmetrically
hemispherical at the apex, being tilted to the left and ventrally, and has a length above the
anterior pore of 0.06 and at its distal termination of 0.80 of the total length of the body. The
hypocone has a length at the proximal and distal ends of the girdle of 0.94 and 0.20 respectively
of the total length of the body. It is somewhat wider and more voluminous than the epicone.
The antapex is broadly rounded and slightly asymmetrical, the suleus terminating in a trough
on the side of the body opposite to that of the anterior pore but without a terminal suleal notch.

The broad girdle joins the sulcus anteriorly at a point 0.06 of the total length of the body
from the apex. It immediately curves posteriorly at about 40° from the horizontal for 0.5 turn
before crossing the dorsal side almost horizontally, then again turns posteriorly at about 45°
for 0.5 turn, slackening in the distal 0.25 turn almost to the horizontal again, making in all 1.4
turns before joining the sulcus distally, at a point 0.2 of the total length of the body from the
antapex. Its total displacement is thus about 0.75 length of the body. The anterior flagellar
pore lies at the anterior junction of the girdle and suleus, the posterior one posterior to the
distal junction. The furrow has a width of 0.09 transdiameter and is not deeply impressed.
The transverse flagellum traverses the girdle for about 0.25 of its length. The pores open on
opposite faces of the body. :

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 449

The suleus takes origin in a rounded depression only slightly above the anterior flagellar
pore. It sweeps around the body as a narrow shallow trough about 0.33 the width of the girdle
for 0.75 of its circumference, ending on the right margin of the dorsal side of the antapex. The
suleus widens to three times its width above, after its posterior junction with the girdle.

The ocellus is situated on the ventral face at the left of the suleus, slightly anterior to the
equator. Its length is about 0.25 transdiameter and its axis horizontal. It is directed to the
left. It consists of a hemispherical melanosome with a rufous central core in which the base of
the smaller lens is embedded. Near the lens is a horizontal row of five unequal, highly refractive
spherules appressed in one mass, the one nearest the lens being a nearly spherical hyaline mass.
They are composed of greenish opaque material resembling the lens in color but less hyaline.
They appear to be products of metabolism rather than parts of a lens of the diffuse type. Several
masses of rufous-black pigment are scattered along the anterior border of the girdle below the
ocellus.

The nucleus is large, spheroidal, ovoidal or ellipsoidal, and centrally located. Distinet
chromatin strands follow its major axis. Its major and minor axes are 0.7—0.9 and 0.6—0.4
transdiameter in length respectively.

A small ovoidal pusule opens anteriorly into the anterior flagellar pore. The cytoplasm is
finely granular with few to many food vacuoles. In the individual figured the irregular wrinkled
skirt of protoplasm protruding from the antapex is the discharge vent opened by the ejection
of a large food mass. The same appearance has been noted in other forms with the actual
discharge of a food mass. Later it was completely retracted in the individual figured.

The surface of the body presents a number of distinct longitudinal striations on the hypocone,
sixteen on one face. There are faint indications of striae on the central section of the epicone,
but none elsewhere. There are no peripheral vacuoles other than slight accumulations along
the striae.

The coler is a pale lavender diffused through the cytoplasm, being more dense at the periphery
than throughout the main body and a trifle darker anteriorly, suggesting an axial gradient in
metabolism.

Dimensions.—Length, 1454; transdiameter, 92H; axes of nucleus, 60“ and
63; length of ocellus, 20.

OccURRENCE.—One individual was taken in a haul made 4 miles off La Jolla,
California, on July 11, 1917, with a No. 25 silk net from 80 meters to the surface
and in a surface temperature of 19°7 C.

Activities.—The turns of the spiral of the contracted transverse flagellum
were very close set and the waves of contraction running through it distally
were extraordinarily rapid. The animal moved intermittently in clockwise
circles of a diameter several times its length, without rotation on its axis. The
progress was noticeably intermittent and jerking and is due either to the tem-
porary attachment of the trailing flagellum to the substrate or to its intermittent
action, apparently to the latter primarily.

Comparisons.—This is a very highly specialized representative of the sub-
genus Pouchetia with integrated ocellus. Both lens and melanosome are com-
pact and their union is intimate. In volume also it is a large species, in fact
the largest in the genus. It shares the structural features of median ocellus
of integrated type in a horizontal position and large size of body with P. juno
(fig. OO, 3) and P. violescens (fig. OO, 1). It differs from them in one im-
portant feature, namely, the very great displacement between the proximal and

450 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

distal ends of the girdle, 0.75 length of body, as compared with 0.5 or less in
the two species named. The consequence is that the apical loop of the sulcus,
so prominent in these two species, is practically eliminated in P. maxima. It
is also striated as are P. violescens and P. striata (figs. OO, 1, 8), thus adding
development of surface markings and marked expansion of the furrow and
sulcus to the other indications of specialization.

Pouchetia panamensis Kofoid
Text figure PP, 7
Pouchetia panamensts Kofoid (1907b), pp. 164, 167, pl. 1, fig. 7.

DriacNnosts.—A minute species with ovoidal body, its length 1.6 transdiam-
eters; girdle a descending left spiral, displaced nearly 0.7 transdiameter, and
making 1.25 turns; sulcus extends nearly to apex, its torsion nearly 0.5 turn;
ocellus subspheroidal with minute central lens; plasma rose pink. Length, 34+.
Pacific, Bay of Panama, October.

DerscripTion.—The body is slightly ovoidal, widest below the equator, its length 1.6 greatest
transdiameters. The epicone and hypocone are almost equal, apex hemispherical, antapex more
pointed, hypocone somewhat flattened ventrally. The girdle forms a descending right spiral
with a very regular descent for 1.25 turns and has total vertical displacement of about 0.7
transdiameter, or 0.43 the total length. The furrow is slightly impressed without marked lps
and is relatively very wide, being 0.16 transdiameter in width. The suleus is about 0.25 the
width of the girdle and extends from within 0.12 of the total length of the body from the apex
to the posterior end, where it flares out in a terminal pocket. The total torsion of the sulcus to
the left is a little less than 0.5 turn. The flagellar pores are at the junctions with the girdle.
The anterior flagellum runs the entire length of the girdle; the length of the longitudinal one
is about 0.5 the length of the body.

The ocellus lies at the left of the junction of the suleus and the distal end of the girdle. It
is a minute body about 0.2 transdiameter in diameter. It consists of a subspheroidal, notched,
black melanosome with irregular surface in the left anterior side, of which a very small spherical
lens is deeply embedded, so that the melanosome forms a stout crescent about it. The lens as
exposed is only about 0.25 the diameter of the melanosome in diameter. The nucleus is also
relatively small. It is an ellipsoidal body centrally located below the equator with its major and
minor axes respectively 0.40 and 0.24 transdiameter in length. It lies obliquely to the main axis.
Spherical droplets are scattered in the peripheral plasma. The color is a diffuse rose pink fading
out posteriorly and deepest near the anterior end.

One individual was enclosed in a concentric, trilamellate cyst, the length of which was nearly
three times the length of the body. Its surface was gelatinous and was covered with adherent
particles of débris.

Divensions.—Length, 34; transdiameter, 21; ocellus, 4+; nucleus, 8+.

OccURRENCE.—Several individuals seen in surface collections of plankton
made with a No, 20 silk net by the senior author while on the Agassiz Expe-
dition to the Eastern Tropical Pacific in 1904-05 in the Bay of Panama, at the
ship’s anchorage, October 23, 1904, in a surface temperature of about 27° C.

CoMPARISONS.—With the exception of P. parva Lohmann, P. panamensis
is the smallest species in the genus. It has the lens reduced to the merest

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 451

rudiment. It is one of the simplest species of the subgenus Pouchetiella with
ocellus of the concentrated or integrated type and has no nearly related species
in so far as proportions, furrows, and ocellus reveal relationships.

Pouchetia parva Lohmann
Text figure PP, 6

Pouchetia parva Lohmann (1908), pp. 147, 202, 252, 264, 366, table B, pl. 17, fig. 23.
Figure inverted.

P. paron, Lohmann (1908), p. 869. Lapsus.

P. parva, Paulsen (1908), p. 106, fig. 148. Figure inverted.

.P. parva, Lohmann (1911), pp. 30, 31, pl. 1, fig. 5; pl. 4, fig. 12d.

P. parva, Ostenfeld (1913), p. 388.

P. parva, Lebour (1917b), p. 198.

Draenosts.—A minute species, irregularly and asymmetrically ovoidal, its
length 1.6 transdiameters; girdle making probably 1.5 turns with considerable
displacement; sulcus unknown; ocellus postmedian, lens spheroidal irregularly
laminate, melanosome pyriform in outline; coler, ochraceous. Length, 33.
Baltic at Kiel; Plymouth Sound.

Descriprion.—Lohmann’s (1908, 1911) figures of this small species are so incomplete as to
make even its generic allocation a matter of uncertainty, especially since the girdle and sulcus
are not shown. The following account is based on his figure interpreted in the light of our
comparative knowledge of the genus.

The body is irregularly ovoidal and asymmetrical, or even almost biconical in its contour,
with the shorter cone or broader end anterior. Both Lohmann (1908, 1911) and Paulsen (1908)
invert the figure and place the pointed end anterior. However, the relations of the ocellus are
in harmony with those elsewhere in the genus if we invert Lohmann’s figure, place the pointed
end posterior and thus point the lens anterosinistrally. The indications of the girdle also favor
such an interpretation. The length is 1.6 transdiameters at the widest part which is anterior to
the girdle and to the middle. The epicone appears to exceed the hypocone in size. The epicone
is convex subconical with an angle of about 50° and a broadly rounded apex. The hypocone
has about the same angle, is less symmetrical, more prolonged, protuberant near the ocellus,
excavated below it, and terminates in contracted, bluntly pointed antapex, reflexed to the right
and dorsally.

The absence of the ochraceous color in this antapical tip in Lohmann’s (1911, pl. 4, fig. 12d)
third figure of this species appears to be an oversight. Otherwise one might interpret it as a
developing cyst detached only posteriorly from the surface pellicle of the body. In his second
figure (1911, pl. 1, fig. 5), drawn without a cyst wall, there is no suggestion that this extension
is not a part of the body, and in the original figure (pl. 17, fig. 23) it is colored with the same
ochraceous tint as the remainder of the body.

The girdle is not portrayed sufficiently to enable one to define its course with certainty. It
forms a descending left spiral. The asymmetrical antapex is suggestive of at least 1.5 turns
and a displacement of about 0.75 transdiameter. The furrow, as drawn, is only slightly im-
pressed. The sulcus is not indicated in any way, unless it be that the line across the antapex
represents a posterior turn of this groove somewhat as in Nematodinium. If this be sulcus there
may be at least a full turn of the suleus about the body.

452 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The ocellus is quite large, 0.5 transdiameter in length, and is located just posterior to the
middle of the body, below the girdle, and apparently in the typical position at the left of the
intereingular suleus. Its axis stands at about 45° above the horizontal and it is directed antero-
sinistrally. It is quite protuberant and appears to be crowded against the suleus. It is of the
simple or concentrated type, consisting of a spherical lens and massive pyriform (?) melanosome.
The lens is somewhat irregularly subdivided into several unequal lamellae and is slightly
embedded on one face in the larger end of the melanosome, which is larger than the lens, its
major and minor axes being respectively 1.5 and 1.25 diameters of the lens in length.

The color of the body is diffuse ochraceous. This species is often found in a transparent,
close fitting cyst within which binary fission occurs with resulting temporary chain formation of
the two sister organisms.

Dimensions.—Length, 33+; greatest transdiameter, 20/; length of the ocellus,
10+.

OccuRRENCE.—Reported by Lohmann (1908, 1911) from the plankton of
the Baltic Sea at the entrance to Kiel Harbor from April to November, in
surface temperatures of 5° C to 19° C. The plankton was collected by the cen-
trifuge method and the numbers per 100 liters range from less than 500 or too
few for enumeration to 50,000. This maximum was found on May 16, 1906, at
the surface in a temperature of 12°6 C, as shown in Lohmann’s table B. His
statement in the text (1908, p. 263) that the maximum was 230,000 appears to
be in contradiction to the table and to his own previous citation of the 50,000
maximum. He finds the species avoiding the deeper waters at his collecting
station, where the depth was 15 to 16 meters. On the 23 days on which it was
found in the series of 60 sets of samples from different levels from April 12,
1905, to August 17, 1906, it occurred 15 times at the surface, 12 times at 5 meters,
and only 3 times at 15 meters. The influence of light is thus evident in its
distribution.

Miss Lebour (1917) reports it from Plymouth Sound as ‘‘frequent in
summer, especially in June.’’ She states, however, that ‘‘this species is very
like Pouchet’s figure (1885) of P. polyphemus var. nigra. The pigment, how-
ever, in his species is red and this is always black.’’ Since Pouchet did not
describe his Gymnodinium polyphemus var. nigrum until 1887, and never stated,
so far as we can find, that its pigment was red, it seems that Miss Lebour must
consider his var. nigrum (1887) as the equivalent of his polyphemus (1885),
although his figures of 1887 show black pigment, but no red. As shown else-
where by us (p. 000), we regard Pouchet’s G. polyphemus (1885) and his G.
polyphemus vars. nigrum and roseum (1887) as three distinct species. The
uncertainty thus raised by Miss Lebour’s statement makes the allocation of her
record of occurrence to P. parva Lohmann somewhat tentative.

Comparisons.—This is the smallest species known in the genus Pouchetia.
It isa member of the subgenus Pouchetiella with concentrated or simple ocellus,
and, in so far as indicated by the structure of the ocellus, is nearest P. juno,
P. purpurata, P. rubescens, and P. violescens, though probably of simpler
organization than these species in other features. There appears to be no prob-
ability that it is near Protopsis nigra (Gymnodinium polyphemus var. nigrum

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 453

Pouchet), as intimated by Miss Lebour (1917b), since the ocellus is of the
diffuse type in Protopsis nigra and of the simple or concentrated type in Pou-
chetia parva. The shape, size, and proportions of the body are quite different
in the two and the girdle, as we have indicated above, appears to be of the
Pouchetia type with torsion, rather than of the Gymnodinium type with none,
as in Protopsis.

Pouchetia polyphemus (Pouchet) emend.
Text figure OO, 11

“Voisin de Gymn [odiniwm] spirale Bergh et Archimedis Pouch.’’ Pouchet (1885a), pp.
38-41. Pouchetia polyphemus sensu latw. Indeterminable.

**Peridinium voisin de Gymnodinium spirale,’’ Pouchet (1885a), p. 85, pl. 2, figs. la-c.
Three different forms figured, all Pouchetia, but indeterminable.

Gymnodinium polyphemus Pouchet (1885b), pp. 529-531, pl. 26, fig. III. Fig. IV is a
different and an indeterminate species of Pouchetia; (1886), pp. 228-224; (1887), pp.
101, 112; (1894), p. 175.

Gymnodiniums polyphemus Pouchet (1885b), p. 529. Lapsus.

Gymnodinium polyphemus Pouchet (1887), pl. 10, bottom, Zapsus. Plate contains figures

of Gymnodinium polyphemus var. rosewm, pl. 10, fig. 1 (— Pouchetia roseum (Pouchet) )
and Gymnodinium polyphemus var. vigrum, pl. 10, figs. 2 A-B, 3, 4 (= Protopsis nigra
(Pouchet). Figs. 2 C and 5 are indeterminable.

Gymnodinium polyphemus, Schiitt (1895), pp. 94, 95.

DraGnosis.—A large species with elongated, curved, ellipsoidal body, length
2.2 transdiameters ; girdle with about 1.75 turns, displaced about 0.5 total length
of body; sulcus with at least 2 turns, with apical and antapical loops; ocellus
premedian, simple, with elongated hemispherical lens and somewhat irregular
pigment mass, plasma colorless. Length, 104. Atlantic, Concarneau, France ;
Dyrefjord, Iceland, July and August.

DescripTion.—F rom our current knowledge of this genus, together with the indications of
girdle and suleus in Pouchet’s figure, we are able to complete tentatively the structural features
sufficiently to obtain a fairly diagnostic account of this species. This interpretation is repre-
sented in the modified figure (text fig. OO, 11) based on Pouchet’s (1885b, pl. 26, fig. 3), in
which we have interpreted his partially drawn suleus and girdle as beneath instead of on the
upper side of the figure as he has drawn them. As is frequently the case in Pouchet’s plates,
this figure has its posterior end uppermost on the plate.

The body is elongated, ellipsoidal, flattened ventrally, broadly convex dorsally, the dorsal
side forming an are with a radius of 1.5 transdiameters. The length is 2.2 transdiameters at
the widest part which is a little anterior to the middle. The epicone and hypocone are subequal.
The apex is an asymmetrically flattened hemisphere, with the antapex contracted and deeply cleft
by the suleal indentation with pointed prolongations on either side.

The girdle begins at the right and anterior to the ocellus, about 0.5 transdiameter from the
apex, makes about 1.75 turns in a uniformly descending left spiral, joining the suleus again
posteriorly somewhere near 0.5 transdiameter from the antapex. There is a total intereingular
displacement of a little more than one transdiameter. The figure was evidently made from a
moribund individual and the furrow is seareely impressed, except anteriorly. The suleus evi-
dently has well defined anterior and posterior loops beyond the intercingular region. The

454 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

anterior loop makes nearly 0.75 turn, the intercingular region has about the same amount of
torsion, and the posterior loop somewhat more than 0.5 turn, a total torsion of approximately
2.25 turns. Uncertainty attaches to the distal limit of the suleus anteriorly and to the exact
location of the flagellar pores.

The ocellus is of the concentrated or integrated type. It is located at the anterior angle of
the hypocone, 0.33 of the total length from the anterior end at the left of the suleus and just
posterior to the girdle. Its length is 0.25 transdiameter. Its axis appears to be parallel to the
major axis of the body and is directed anteriorly. It consists of an elongated subhemispherieal
lens whose exposed length equals its diameter and a ragged disk of pigment (reddish brown on
the plate), the diameter of which is twice that of the lens and 0.25 transdiameter of the body.
The color of the pigment of the individual figured is not stated in the pertinent text.

The nucleus was so transparent as to have eluded observation. There is a large clavate
pusule near the ocellus, evidently attached to the anterior flagellar pore. The cytoplasm is
stated to have been transparent, colorless, and coarsely vacuolated. A red pigment fleck lies on
the anterior margin of the anterior loop of the suleus. Free and encysted forms were seen.

Drvenstons.—Length, 104“; transdiameter, 47; length of ocellus, 12.

OccurRENCE.—Figured from the Atlantic at Concarneau, France, by Pouchet
(1885b) and stated by him later (1892, 1894, p. 170) to oceur in typical form
in the plankton of Dyrefjord, Iceland, in July and August, at 10° C.

Comparisons.—This species is the only one in Pouchetia with an ocellus so
far anterior except P. compacta Schiitt, and there is some doubt about the
orientation of that species. P. fusus Schiitt and P. maxima sp. nov. have a
premedian ocellus, but not so far anterior as in P. polyphemus. The bifid
antapex, the character of the anterior and posterior loops of the sulcus, and
the orientation of the ocellus combine to confirm the correctness of the orien-
tation which we have given to Pouchet’s figure. This species is not far from
P. juno and P. violescens in girdle, suleus, size, form, and structure and location
of the ocellus. The differences between them appear to lie in the color and
surface differentiations and in the direction of the axis of the ocellus. P.
polyphemus is colorless and has neither longitudinal markings nor platysomes ;
the axis of its ocellus is longitudinal, while in the two species named this axis
is horizontal. P. violsecens is colored and has longitudinal markings and P.
juno has peculiar platysomes. Pouchetia polyphemus belongs in the subgenus
Pouchetiella.

SynonyMy.—This species was originally described by Pouchet (1884,
1885a, b), apparently from a complex of forms which he did not clearly analyze,
and within which he noted (1885a@) a considerable range in size, color, and
structure, which he imperfectly interpreted, and an inconstancy of occurrence
of the ocellus. These facts, with our present knowledge of the group, afford
conclusive proof that he confused species of Pouchetia with those of other
genera, and establish also the probability of confusion of species within the
genus of Pouchetia itself.

His statement (1886) that the ocellus develops by the fusion of the refringe-
ent spherules into one body and the retraction of the pigment into one cap-
shaped mass seems rather to be a hypothetical interpretation based on different

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 455

individuals or species than an analysis of development. Any delimitation of
P. poluphemus (Pouchet) must therefore be based upon his figures and such
parts of his text as are descriptive thereof.

In his earler papers (1884, 1885) Pouchet discussed the ocellus and (1885a,
pl. 2, figs. la-c) figured several forms, each with an ocellus, but did not designate
the species beyond stating in his explanation of the plate that one of them was
‘‘voisin de Gymnodinium spirale.’ The two or three forms figured in this
paper are, in the absence of comparable material, clearly indeterminable be-
yond the probability that they belong to the genus Pouchetia. It is possible
that his figure of the lens will permit the detection of one of these forms when
rediscovered.

In a later paper (18855) Pouchet figures, briefly describes, and names Gym-
nodinium polyphemus, a different form from that previously (1885a) figured,
and at the close of his statement refers the reader to his earlier paper (1885a).
In view of this sequence we restrict the name polyphemus to the organism
named in his later paper, delineated in the first of his figures (1885), pl. 26,
fig. 3). The second figure (see his pl. 26, fig. 4) is a smaller organism, also with
ocellus, in binary fission in a cyst, and so lacking in details as to be wholly
indeterminable. It is therefore excluded from Pouchetia polyphemus.

Neither Schutt (1895), who established Pouchetia and refers to this species,
nor Lemmermann (1899), who compiled its species, refer Gymnodinium
polyphemus to Pouchetia. Pouchet’s confusion of species might invalidate the
accuracy of his record of this same species in the warm waters off the coast of
France and in the colder waters off Iceland.

Pouchetia poucheti sp. nov.
Plate 11, figure 125; text figure PP, 4

DraGnosis.—A rather large species; body broadly ellipsoidal, length 1.3
transdiameters; girdle a descending left spiral of 1.2 turns, displaced 0.6 trans-
diameters: sulcus with apical and antapical loops, torsion 0.75 turn; ocellus
diffuse, median, with distributed lens, lobed melanosome, scattered pigment ;
color, bluish green. Length, 73. Pacifie off La Jolla, July.

DescripTion.—Body rotund, broadly ellipsoidal with slight irregularities. The epicone is
nearly 0.25 smaller in length than the hypocone. Its apex is broadly rounded, higher at the
right end, its outline notched on the right side by the apical loop of the suleus, which here
reaches the apex. It has a length above the anterior flagellar pore of 0.3 and at the distal
extremity of the girdle of 0.8 of the total length of the body. The hypocone is also broadly but
asymmetrically rounded, being prolonged beyond the hemispherical and slightly pointed at the
right with its outline somewhat irregular on the left due to the shallow trough made by the
antapical section of the suleus. The shallow suleal notch lies 0.3 transdiameter to the left of the
antapex.

The anterior junction of the girdle and suleus is loeated 0.3 of the total length of the body
from the apex. The girdle passes around the body in a descending left spiral which in the
proximal 0.5 turn is nearly horizontal and is then deflected to a uniform slope of 25° from the

456 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

horizontal for the rest of its course. It meets the suleus at a point 0.16 of the length of the
body from the antapex. It forms a broad trough in a shallow constriction with the borders
slightly overhanging. The anterior flagellar pore is located at the anterior junction of the
girdle and sulcus and the posterior pore is found at the postmargin beyond the posterior junction
of girdle and suleus about the width of a girdle. The transverse flagellum traverses about 0.2
of the length of the girdle.

The suleus invades the hypocone in a broad apical loop of 0.5 turn, terminating near the
apex. It forms a broad channel, only slightly narrower than the girdle, the lips on the epicone
forming a high ridge on its left and a lesser one on its right side. In its course below the anterior
flagellar pore it forms a deep trough which becomes shallower on reaching its distal Junction with
the girdle, and continues so in its path down the hypocone to its termination to the left of the
antapex. It forms an irregular descending left spiral with torsion of 0.75 turn. It is not
improbable that an antapical loop completes a full turn dorsally.

The ocellus is situated in the equatorial region, at the left of the intercingular sulcus. It is
of the diffuse type in its least integrated stage. It consists of a loosely aggregated group of
lenses and seattered melanosome. The lens is formed of six spherical, clear, bluish hyaline bodies
loosely massed together in an irregular linear series 0.33 transdiameter in length. The melano-
some is composed of more than a score of irregular, unequal spheroids of black pigment, varying
in size from 0.5—6, in diameter and scattered in the peripheral plasma at the left and posterior
to the lenses, from the left of the anterior flagellar pore to near the antapex along the left margin
of the hypocone. The larger masses are found near the distal end of the lens. To the left of
the lens and closely associated with it is a long slender body, yellow ochre in color. It may be
the homologue of the pigmented core of the more integrated types of melanosome. Its axis is
directed anterosinistrally at 15° from the vertical.

The nucleus is just postequatorial, ellipsoidal in shape with no visible chromatin strands in
the individual figured. Its major and minor axes are 0.40 and 0.26 transdiameters respectively
in length.

A large, club-shaped pusule opens anteriorly into the anterior flagellar pore. A posterior ©
one was not noted. The cytoplasm is clear and finely granular. In the anterior portion of the
body and radiating from near the anterior flagellar pore is a group of slender, linear, green
rodlets or fluid-filled canals. In the midregion and sparingly elsewhere are small blue-green
oil droplets. A large primuline-yellow food mass was present near the ocellus. Thickly seat-
tered in the peripheral plasma are irregular, thin, uniformly distributed vacuoles filled with
blue-green fluid. No surface markings or striations were present.

The general color is a pallid methyl blue mottled with the blue-green of the surface vacuoles.
The body was surrounded by a close fitting hyaline cyst which during observation became more
and more distended in the region of the suleus, especially over the apical loop.

DiMENsiIons.—Length, 73; transdiameter, 54; axes of nucleus, 26# and 14+.

OccURRENCE.—One individual was taken July 25, 1917, 11 miles off La Jolla
with a No. 25 silk net in a haul from 80 meters to the surface in a surface
temperature of 27°1 C.

Comparisons.—This is the most primitive species of the subgenus Pouchetia
with diffuse ocellus. Its primitive features are shown in the slight intercingular
torsion and in the marked absence of integration in the ocellus as shown in the
degree of independence of the elements of the lens and the much divided and
widely seattered melanosome. The possibility of disintegration prior to cytoly-
sis is not excluded. As a rule, however, the ocellus resists these disintegrative
processes longer than the cytoplasm,

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 45

~

Pouchetia purpurata sp. nov.
Plate 8, figure 87; text figure PP, 3

Dracnosis.—Medium sized species with obovoidal body, widest anteriorly,
length 1.75 transdiameters; girdle a descending left spiral of 1.4 turns, dis-
placed 0.48 of the total length; sulcus with apical extension and antapical loop;
torsion 1.2 turns; ocellus distributed, postmedian; lens elongated, segmented;
melanosome amoeboid, with granular processes; plasma dahlia purple. Length,
88. Pacifie off La Jolla, California, July.

Description.—The body is obovoidal, wider anteriorly, flattened ventrally, more convex
dorsally, its length 1.75 transdiameters measured at the widest part which is about the level of
the anterior flagellar pore. The epicone exceeds the hypocone in height by about 0.13 of its
own length and is wider and more rotund. Its length at the proximal and distal ends of the
girdle is 0.3 and 0.8 respectively of the total length of the body. Its ventral face is somewhat
flattened, the dorsal more convex. The apex is subhemispherical. The hypocone is more con-
tracted, its length at the anterior and posterior ends of the intercingular suleus being 0.7 and
0.2 respectively of the total length. The antapex is rounded and somewhat projected ventrally
by the arching of the dorsal side.

The girdle leaves the suleus 0.3 of the total length below the apex, makes 0.5 turn of a
descending left spiral with almost no posterior deflection, steepens rapidly 0.75 turn to 45°
and slackens up almost to the horizontal at its distal end of nearly 0.5 turn. It makes a total
of 1.4 turns with a total displacement of 0.48 total length, or 0.85 transdiameter. The furrow
has a width of 0.08 transdiameter, is not deeply impressed and has a somewhat overhanging
anterior lip. The suleus was not fully determined on the epicone. It appears to start near the
apex, curves but slightly in place of the usual apical loop, but runs from apex nearly to the
antapex in a fairly uniform descending left spiral with a total torsion of 1.2 turns, 0.6 of which
is in an abruptly steepened antapical loop. It is a narrow channel about 0.5 the width of the
furrow in the intercingular region, but widens out below in the antapical loop. The flagellar
pores are at the junctions of girdle and sulcus and the transverse flagellum runs the whole
length of the transverse furrow.

The ocellus is of the diffuse type, postmedian, at the left and close to the distal end of the
intercingular sulcus. Its length is unusually great, attaining 0.28 total length of the body, or
nearly 0.7 transdiameter. Its greatest diameter is 0.35 of its own length. It lies parallel to
the suleus with the lens direeted anterodextrally at an angle of about 35° from the vertical.
The lens is hyaline, glaucous green in color with a darker purplish plasma sheath surrounding
it and separating its segments. It is a slender shaft of four unequal segments enclosed within
a less distinctly differentiated outer sheath. This sheath is incomplete on its sinistral face. The
melanosome is more than 0.35 wider than the lens, its main mass forming a stout pitcher-shaped
body into which the end of the lens is thrust. From its anterosinistral margin a lobe projects
anteriorly and breaks up into an anastomosing, branching network of granular strands of
pigment. A disconnected strand of similar granules lies along the anterior lip of the furrow,
and several others in the peripheral plasma of the hypocone adjacent to the distal end of the
girdle and sulcus.

The nucleus is relatively small. It is an elongated, asymmetrical ellipsoid, located far
anterior in the center of the epicone. Its axes are 0.6 and 0.33 transdiameter in length respeec-
tively and it is crowded with spirally wound, beaded chromatin threads. A pale ochraceous
food ball lies in the center of the very transparent plasma. A cluster of slender, greenish
diverging radial rodlets are located in the extreme posterior end, probably metabolic in origin.
In the peripheral plasma close to the pellicle are minute, uniformly distributed, greenish droplets.

458 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

No pusules were noted. The plasma is a delicate dahlia purple, deepest peripherally and fading
a little from the anterior end posteriorly, as though revealing some biochemical axial gradient.

One of the animals seen was enclosed in a roomy, transparent cyst proportioned in contour
to the body and filled with a fluid tinged with the color of the organism. Its length was 1.18
that of the body.

Dimenstons.—Length, 88; transdiameter, 52; length of ocellus, 354; axes
of nucleus, 354 and 17; length of cyst, 95v.

OccURRENCE.—The individual figured was taken July 25, 1917, 11 miles off
La Jolla with a No. 25 silk net in a haul from 80 meters to the surface in a
surface temperature of 21°2 C. It occurred again on July 27 in a haul of
similar nature taken 4 miles off La Jolla in a surface temperature of 21°9 C.

Activrtres.—The first individual studied was encysted when found. Under
the cover glass, however, it broke out of the cyst and moved quickly across the
slide in an almost straight line, with a rapid anticlockwise rotation.

ComPparIsons.—This species belongs to the subgenus Pouchetia with diffuse
non-integrated ocellus. The lens, in fact, is scarcely organized as an efficient
optical organ, and the pigment is distinctly amoeboid and rather widely dis-
tributed. In this feature it is near P. schuetti, but differs from it entirely in
proportions, color, and shape and structure of the lens. In color it is unique
in Pouchetia, the dahlia purple being of a different tone and darker than the
rosy tints of P. schuetti and P. rubescens. The axial gradation in color from
the anterior end posteriorly is not unlike that in Gymnodinium sulcatum, G.
rubricauda, and Gyrodinium rubrum, but the reverse of that in G. postmacu-
latum, all species with more or less diffuse reddish to purplish coloration of the
plasma (pl. 8, figs. 83, 88, 86, 91).

Pouchetia purpurescens sp. nov.
Plate 8, figure 84; text figure OO, 7

DIAGNosIs.—Small species with body asymmetrically ellipsoidal, deeply con-
stricted by furrows; length 1.7 transdiameters: girdle forms a descending left
spiral of 2 turns, displaced over 0.75 total length; sulcus with short apical loops
and torsion of 1 turn; ocellus concentrated, posterior, horizontal, small, appar-
ently at the right of the suleus; lens spheroidal, melanosome hemispherical, with
red central core; plasma amaranth purple. Length, 594. Pacific off La Jolla,
California, June, July.

Descriprion.—The body is ellipsoidal, asymmetrical at either end, with the posterior portion
of the epicone covering the ocellus and forming a projecting lobe. The body is deeply constricted
and rendered asymmetrical by the spiral sulcus. The epicone and hypocone are nearly equal.
The epicone is small at its anterior end with a length of 0.06 of the total length of the body at
the proximal end of the girdle. From this point it sweeps around the body posteriorly in a
broad band about 0.55 transdiameter in width, which terminates at a distance from the antapex
of 0.1 of the total body length. The apex is broadly rounded. The hypocone follows the epicone
in its course around the body with a slightly broader band which terminates in a button-shaped

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 459

eminence at the antapex. The antapical region is grooved ventrally by the suleus, which forms
a deep trough, to the right of which the hypocone swells out to a broad, shghtly rounded lobe,
asymmetrically placed at the right of the shallow sulcal notch in the postmargin.

The girdle at its proximal end is distant 0.06 of the total length of the bedy from the apex.
It curves around dorsally in a horizontal semicircle before beginning its posterior direction in
a steep descending left spiral 60° from the horizontal. It makes two complete turns around the
body and joins the suleus distally 0.1 of the length of the body from the apex, flattening the
spiral again to the horizontal gradually in the last 0.75 turn. Its displacement thus equals 0.84
of the length of the body. The furrow is deeply impressed and is 0.1 transdiameter in width.
The anterior flagellar pore opens at the junction of the girdle and sulcus. The transverse
flagellum traverses one-half the entire length of the girdle. The posterior flagellar pore is
found at the distal junction of the suleus and the girdle. Both pores open on the ventral face.

The suleus invades the epicone half the short distance to the apex. It makes one complete
revolution of the body in a uniform steep descending left spiral as a narrow channel in a deep
furrow, widening distally, and beyond the flagellar pore spreading out as a broad trough, one
side of which partly encircles the distal eminence of the hypocone, forming a broad notch in
the outline of the body viewed dorsoventrally.

The ocellus is of the concentrated type. It is situated 0.25 of the total length of the body
from the posterior end on the right of the distal end of the suleus instead of the left, as usual
in Pouchetia, occupying a somewhat protruding, posterodextral portion of the epicone. Its
length is almost 0.25 transdiameter and its axis is horizontal with the lens directed to the left.
In a second individual it was directed anterodextrally 45° from the horizontal. It is composed
of a hemispheroidal melanosome with a brilliant red central core, partly surrounding the base
of the simple spheroidal lens of about the same size as the melanosome. The lens is a clear,
hyaline, asymmetrical sphere with faint indications of concentric layers and the melanosome is
without indications of amoeboid processes. In a second individual of larger size the melano-
some was flattened and twice the diameter of the somewhat elongated lens. Both lens and
melanosome were less symmetrical than in the individual figured. As cytolysis approached the
lens flattened into a dise with an axial button.

The ellipsoidal or spheroidal nucleus is situated near or somewhat posterior to the middle of
the body. It is ellipsoidal in shape in the individual figured with major and minor axes of 0.6
and 0.4 transdiameter respectively. Chromatin strands follow its major axis.

No pusules were noted in the eneysted individuals examined. The cytoplasm is clear or
finely granular with few or many larger granules and oil globules. The individual figured
showed no granulations or vacuoles and but one large, rounded, ochraceous food mass enclosed
in a vacuole.

The surface of the body presents no striations or other markings and there are no peripheral
vacuoles. In one individual, as cytolysis approached, minute lines and lenticels of colored fluid
gathered in the peripheral plasma with some indications of a longitudinal linear order 10-12
across one face. The color is amaranth purple diffused through the cytoplasm. The color may
become aggregated into small blotches or into strands or threads peripherally located as above
noted, leaving the adjacent cytoplasm colorless. Both individuals examined were contained in
thin, hyaline, close fitting cysts.

Dimenstons.—Length, 59-68; transdiameter, 35-394; axes of nucleus,
22-27» and 16-22»; length of ocellus, 9; its greatest width, 7.5.

Acrivities.—Both individuals examined showed no active movements be-
yond continuous vibrations of the transverse flagellum without rotation within
the cyst.

460 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

OccURRENCE.—One individual was taken from the surface haul made with
a No. 12 silk net at the end of the pier at the Biological Station at La Jolla,
California, on June 7, 1917, in surface temperature of 17°3 C, and the other
from a haul made 4 miles offshore with a No. 25 silk net on July 11, 1917, from
a depth of 80 meters to the surface and in a surface temperature of 19°7 C.

Compartsons.—The purplish color of the plasma somewhat resembles that
of P. purpurata and Gyrodinium postmaculatum, although the species P. pur-
purescens has little else in common with either of these species. P. fusus is the
only species equaling it in the amount of torsion (2 turns) of the girdle and
suleus combined. The location of the ocellus at the right of the suleus instead
of the left is unparalleled in the genus Pouchetia. This species was particu-
larly puzzling and difficult to interpret because of the uncertainties in following
the girdle and sulcus. There is here a possibility of a mistaken interpretation.
Assuming a correct interpretation, it appears that the ocellus has been crowded
from an internal position at the left side of the posterior part of the inter-
cingular suleus to the right side without very marked change in either position
or direction of its axis. This might be due to the crowding of food balls ejected
before encystment. The location of the ocellus was the same in a second encysted
individual, but its axis was turned anteriorly 45°. Since we have little evidence
that the ocellus is subject to marked changes in position in the cytoplasm the
suggestion that this ocellus has been shifted by pressure into an unusual position
from the normal and expected one must be regarded as tentative.

This species is a moderately specialized member of the subgenus Pouchetiella
with integrated lens, as shown by the small and variable ocellus, high coloration,
and extreme torsion of the girdle and sulcus.

Pouchetia rosea (Pouchet) emend.
Text figure OO, 4

Gymnodinium polyphemus var. roseum Pouchet (1897), pp. 93, 96-97, 112, pl. 10, fig. 1.

Not Pouchetia rosea, Schiitt (1895), pp. 94, 95, pl. 26, fig. 92 (=P. schuetti nom. sp.
noy.).

P. rosea, Lemmermann (1899), p. 360. In part, includes P. schuetti.

. rosea, Schroder (1900), p. 14. Based on Schiitt’s figures (1895) (=P. schuettt).

P. rosea, Pavillard (1905), p. 48, pl. 3, fig. 4. Schiitt’s P. rosea (1895) regarded as
problematical.

P. rosea, Paulsen (1907), p. 24; (1908), pp. 105, 106, fig. 146. In part, tentative inclu-
sion of Schiitt’s P. rosea (1895).

P. rosea, Ostenfeld (1913), pp. 338, 358, 476. Allocation indeterminable.

Not Gymnodinium roseum, Dogiel (1906), pp. 20-26, pl. 2, figs. 26-37 (= Chytriodinium
roseum (Dogiel) Chatton (1912), pp. 91-92).

Not Gymnodinium rosewm, Lohmann (1908), pp. 202, 252, 366, 368, tab. B, pl. 17, figs.
24-28 (—G. lohmanni Paulsen (1908), p. 99, figs. 137 A-D).

ae}

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 461

D1acnosis.—A small species with irregularly ellipsoidal body, its length
1.3-1.66 transdiameters; girdle a descending left spiral of at least 1.25 turns,
displaced about 0.5 total length; sulcus with less than 0.5 turn; ocellus with
elongated lens and red pigment mass. Length, 44-58». Atlantic at Concarneau;
Mediterranean at Cette; April, October.

Description.—This is based on Pouchet’s (1887) and Pavillard’s (1905) figures. The body
is irregularly ellipsoidal, with protuberant girdle when free, rounded up when eneysted; its
length 1.66 (1.3) transdiameters. The epicone and hypocone are subequal. Its altitude at the
proximal end of the girdle is about 0.33 of the total length and over 0.66 at the distal end. The
apex is broadly rounded. The antapex of the hypocone is broadly rounded in the eyst, asym-
metrical and longer on its left side in the free state. In the lower one of Pouchet’s (1887) two
figures the postmargin is obliquely truncate and the body lacks the food ball present in the
upper figure. Pouchet states, however, that they represent two individuals. <A similar truneate
appearance follows the extrusion of food balls at the antapex in other species.

The girdle appears to make about 1.5 turns in Pouchet’s figures, but is not completely
portrayed in Pavillard’s. Its displacement is at least 0.5 the length of the body. The furrow is
deeply impressed with protuberant lips in the free state.

The suleus extends (?) a short distance on the epicone, and continues as a narrow groove in
a spiral course of 0.25 to 0.50 turn to the postmargin. :

The ocellus is of the concentrated or simple, more integrated type. It lies at the left of the
posterior part of the intercingular suleus with its axis directed anterodextrally at about 50°
from the horizontal. Its length is 0.40 to 0.45 transdiameter. It consists of an elongated lens
imbedded at one end in a flattened hemispherical bright red pigment mass. In Pouchet’s figure
the pigment is light rose, in Pavillard’s scarlet with darker margin. In the former the lens is
swollen distally and its exposed length equals the diameter of the pigment mass. It shows no
lamellae. In Pavillard’s figure it is 0.65 of the diameter of the pigment mass in length, not
swollen distally, and has several transverse lamellae.

The nucleus lies anteriorly in the epicone, is ellipsoidal in form with its major and minor
axes 0.75 and 0.50 transdiameter in length respectively and oblique to the axis of the body. It
contains fine parallel chromatin threads. An orchraceous food ball or a vesicle filled with a
fluid colored by diatomin is figured by both Pouchet and Pavillard. The former states that the
plasma is completely hyaline with a yellowish tint locally. It is not rosy as figured by Schiitt
(1895) in the forms he refers to this species.

Drvensions.—Length, 44 (58); transdiameter, 25 (46)“; diameter of
nucleus, 17 (34); length of ocellus, 10 (22)». Pouchet states that the length of
the body is 30/; but the figure measures 44 on the basis of the stated magnifi-
cation, 500 diameters. The dimensions in brackets are of Pavillard’s figure.

OccuRRENCE.—T'wo individuals with red pigment mass were taken in a
haul of a No. 12 silk net from 120 meters to the surface on July 7, 1904, about
10 miles southwest of Point Loma, California, in surface temperatures of
approximately 17°-18° C. Their lengths were 45 and 50 and transdiameters
24 and 30» respectively.

Originally described by Pouchet (1887) from the plankton of the Atlantic
at Conearneau, France, where he discovered it on March 25, and at a later visit
on April 23 to 26. The only other record which can be assigned critically to
this species is that of Pavillard (1905), whose figure bears a marked similarity
to Pouchet’s original sketches and has the red pigment mass as originally

462 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

described and figured. Pavillard (1905) records P. rosea as rare in the plank-
ton of the Etang de Thau at Cette, France, on the Mediterranean in October,
1904. Surface temperatures during this month ranged from 18°4 C to 13°9 C.

The only records which can be considered as possibly including P. rosea, as
here delimited, are those of Paulsen (1907) and Ostenfeld (1913) which refer
to specimens seen by the latter in plankton from the North Sea off Tyborn,
Denmark, in March and April, 1900, and from the Cattegat in May, 1898. Their
status is, however, not critically determinable.

ComParisons.—This is the only species in the genus Pouchetia with a red
pigment mass instead of the usual black melanosome. The relatively slight
torsion of the body, about 0.25 turn, the red instead of black pigment and
elongate laminate lens indicate that this is one of the simpler species of the
subgenus Pouchetiella.

The differences between the figures of Pouchet (1887) and Pavillard (1905)
are considerable. Pouchet’s has a length of 44+, Pavillard’s of 584. The former
is 1.66 transdiameters, the latter 1.3 in length. The lens expands distally in
the former and does not in the latter; the former is somewhat angular, the
latter rotund. These differences are possibly referable to the fact that
Pouchet’s specimen was not encysted while Pavillard’s was in a cyst and ap-
parently well rounded up. The upper one of Pouchet’s figures (both are turned
upside down) has an expanded truncate postmargin. This suggests that it had
recently disgorged a food ball such as is seen in the lower figure (compare our
fig. 61, pl. 6) of Pouchetia maxima, which has a similar antapical margin and
had recently discharged a food mass.

SynonyMy.—Originally described by Pouchet (1887) as Gymnodinium
polyphemus var. roseum, but transferred to Pouchetia by Schiitt (1895), who
appled the name to an assemblage of at least two species different from
Pouchet’s. The svnonymy of this species is full of perplexities arising from
the inadequacy of Pouchet’s (1887) original account and figures, from his re-
lating of his form to his @. polyphemaus as a variety, and from Schiitt’s allo-
cation in Pouchetia rosea (Pouchet) of what appear to us to be two distinct
species, neither of which is referable in our opinion to Pouchet’s original P.
roseum. There is also, at present, lack of adequate and critical knowledge of
the limits of variability within the species of this group and of the pathological
changes which the constituent parts of the ocellus may undergo. It is also
possible that encystment may modify the condition and appearance of the ocellus.

In view, however, of the structural features involved in speciation in this
genus as a whole we have arrived at the following tentative solution of the
perplexities surrounding this species:

1. Pouchet’s Gymnodinium polyphemus var. roseum (1887) is a distinet
species, Pouchetia rosea (Pouchet), but not P. rosea (Pouchet) Schutt or
Gymnodinium roseum Dogiel or G. roseum Lohmann. It is not Pouchet’s
G. polyphemus (1885b).

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 463

2. Schiitt’s (1895) Pouchetia rosea (Pouchet) is a complex of forms none
of which is Pouchet’s species, P. rosea. One of these (Schitt’s, pl. 26, figs.
92:12) has the diffuse or compound type of ocellus with divided lens and branch-
ing, amoeboid pigment mass. To this we assign the new name Pouchetia
schuettt. The other and smaller form (Schiitt’s, pl. 26, figs. 92:2) with a
length of 70-594 as compared with 87» in the first group has a concentrated
or simple lens and a solid melanosome. This appears to be a mutilated or con-
tracted individual, possibly moribund. The possibility of a distinct species is
not precluded. We leave it as indeterminable, but probably not P. schuetti
sp. Nov.

The synonymy of the citations of Pouchetia rosea (Pouchet) Schiitt re-
corded by workers subsequent to Schutt (1895) is a matter which cannot be
determined beyond the point of noting their inclusive nature, since none of
them has critically compared his material with the figures of Pouchet and
Schiitt, though Pavillard (1905), Paulsen (1908), and Ostenfeld (1913) have
all noted the perplexing status of P. rosea (Pouchet) Schiitt.

Lohmann (1908) describes as Gymnodinium roseum a new species which
Paulsen (1908) later renames G. lohmanni because of the preoccupation of the
name roseum by Dogiel’s (1906) G. rosewn. Both Lohmann’s and Dogiel’s
names are, however, excluded from Gymnodinium because of Pouchet’s Gym-
nodinium polyphemus var. roseum (1887). Dogiel’s G. rosewm is utilized by
Chatton (1912) as the type species of a new genus Chytriodinium.

Pouchetia rubescens sp. nov.
Plate 8, figure 90; text figure OO, 5

Draanosis.—Medium sized species, obovoidal, length 1.4 transdiameters;
girdle a descending left spiral of 1.2 turns, displaced 0.5 transdiameter; sulcus
with apical loop much displaced ventrally, antapical section short; torsion 1.2
turns; ocellus concentrated, posterior; lens hemispherical; pigment mass
hemispheroidal, dark brown; color, pink. Length, 73. Pacific off La Jolla,
California, July.

Descriprion.—The body is slightly obovoidal, with its widest transdiameter 0.32 of the total
length from the anterior end. The epicone is 0.3 longer than the hypocone, with hemispherical
apical contour notehed at the ventral side of the apex by the suleus. Its length above the
anterior flagellar pore is 0.4 and from its posterior extremity is 0.9 of the total length of the
body. The hypocone is contracted somewhat, bulging ventrally between the furrows, somewhat
flattened ventrally towards the antapex and slightly grooved by the distal end of the suleus.
Its length from its anterior termination to the antapex is 0.5 and from the distal junction of the
girdle and suleus 0.07 of the total length of the body. The antapex is rounded without suleal
notch.

The girdle meets the suleus at a point 0.46 of the total length of the body from the apex,
passes thence around the body 0.3 of a turn before sweeping posteriorly in a descending left
spiral, steepening to 35° from the longitudinal to join the suleus at a point 0.09 of the total

464 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

length of the body from the antapex. It les in a broad, deep depression, and has a width of
0.06 transdiameter and is bordered by overhanging lips. The anterior flagellar pore is located
at the proximal junction and the posterior pore at the distal junction of the girdle and suleus.
The transverse flagellum traverses approximately the entire length of the furrow.

The suleus forms a wide loop above the anteroir flagellar pore, curving over the top of the
epicone just ventral to the apex and terminating midway between that and the girdle. It is
deeply imbedded like the girdle throughout its entire length, the ips forming high overarching
ridges. Below the anterior flagellar pore it sweeps around for 0.5 turn before joining the distal
end of the girdle, beyond which it passes to the antapex directly without antapical loop. Its
total torsion is about 1.2 turns, but the spiral course is obscured by the ventral deflection of the
apical loop.

The ocellus is located far anterior at the left of the distal end of the intercingular suleus
close to the posterior flagellar pore. Its length is 0.37 transdiameter and it is directed antero-
sinistrally at about 45° from the vertical. The ocellus is of the concentrated type with subequal
hemispheroidal lens and pigment mass. The lens is laminated, with three equidistant hyaline
laminae, bluish in color> Closely imbedding its base is the pigment mass of dark brownish black
pigment enclosing the central core of a lighter brown tone.

The nucleus is ellipsoidal and located dorsally shghtly in front of the equatorial plane.
Large chromatin strands follow the course of its major axis. Its axes are 0.57 and 0.40 trans-
diameter in length respectively.

The eyteplasm is finely granular, containing only a few oil globules in the midregion. Two
cinnamon rufous food masses were present in the individual figured. No pusules were observed.
Neither surface markings nor striations were present.

The color is a mottled pink distributed through the cytoplasm, occasionally showing a
noticeable granular appearance. In the specimen figured three small, rose-red globules of pig-
ment were found in the periphery in the equatorial region. The organism was enclosed in a
large, ovoidal, thin, hyaline eyst 1.28 lengths of the body in length.

An eneysted individual (fig. P, 1) was also present in the haul on July 2, 1917, which, from
its size, color, and type of ocellus, we place in this species. The body had rounded up into a
sphere, with a central, spherical nucleus, peripheral hemispherical pigment mass, with adjacent,
detached, partially disintegrated lens. It was immediately surrounded by a delicate, close fitting
film, outside of which, as a cap covering nearly two-thirds of the sphere, was a degenerating,
eytoplasmie cap containing local aggregates of brownish pigment. The whole was enclosed in
an oblong hyaline outer cyst over twice the diameter of the sphere in length. It appears that
the eneysting animal must have shed off or extruded a considerable mass of plasma containing
pigment between the formation of the outer and inner eysts.

Dimensions.—Length, 50-734; transdiameter, 25-50"; axes of nucleus,
25-30» and 15-21; length of ocellus, 9-18; length of cyst, 94”; its transdiam-
eter, 70r.

OccURRENCE.—T'wo specimens, both encysted, were taken on July 2, 1917,
6 miles off La Jolla, California, with a No. 12 silk net in a haul of 60 meters
to the surface and in a surface temperature of 21°9 C. It occurred again on
August 15 in a haul taken 0.75 mile off La Jolla, California, with a No. 25 silk
net from 80 meters to the surface in a temperature of about 22°5 C.

ComPparisons.—Pouchetia rubescens is a typical representative of the sub-
genus Pouchetiella with highly integrated ocellus, in the case of both the lens
and pigment mass. It is near P. subnigra, but differs from it in several fea-
tures. The length of the epicone at the proximal end of the girdle in P. sub-
nigra is 0.3 and in P. rubescens is 0.45 length of the-body and the apical loop of

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 465

the latter crosses the apex while it curves dorsally below it in the former. The
lens is elongate in P. subnigra and hemispherical in P. rubescens. They differ
also in proportions and size of body.

Pouchetia schuetti nom. sp. noy.
Text figures PP, 10, 11

Pouchetia rosea (Pouchet) Schiitt (1895), pp. 95, 96, 169, pl. 26, fig. 92, _,,. Figure 92,,,
marked 93, on plate.

. resead, Lemmermann (1899), p. 360. In part.

. rosea, Schroder (1900), p. 14.

..rosed, Pavillard (1905), p. 48, pl. 3, fig. 4. This is P. rosea (Pouchet).

. rosea, Paulsen (1907), p. 24; (1908), pp. 105, 106, fig. 146. In part, includes P. rosea
Pouchet.

as} Iasi lash tne}

Dracnosis.—A medium sized species of asvmmetrical ovoidal form, expanded
posteriorly, its length 1.4 transdiameters; girdle a descending left spiral of
1.25 turns, displaced nearly 0.5 transdiameter ; sulcus with about 1.5 turns, with
apical and antapical loops; ocellus dispersed with lens of five segments and
black, dendritic, amoeboid melanosome, plasma rosy. Length, 70-87#. Atlantic,
Mediterranean.

DescripTion.—This is based on Schiitt’s (1895) figures 92, ,,, explanations of figures, and
brief textual references. The body is asymmetrically and irregularly ovoidal, flattened ventrally,
convex dorsally, and expanded posteriorly. Its length is 1.4 transdiameters and the dorsoventral
diameter is 0.9 of the transdiameter. The epicone is longer than the hypocone and perhaps
larger. Its apex is rounded and more convex dorsally than ventrally, and, in ventral view,
somewhat flattened transversely. Its lengths at the proximal and distal ends of the girdle are
0.6 and 1 transdiameter respectively. The hypocone is more distended, very convex postero-
dorsally and excavated ventrally, the suleal notch being carried up ventrally and to the right.

The girdle begins a little anterior to the middle of the body, makes an even descent of a full
turn of a descending left spiral, steepens distally rather abruptly as it joins the suleus, com-
pleting in all at least 1.25 turns. Its distal end is only about 0.2 transdiameter from the post-
margin. The furrow is about 0.06 transdiameter in width with well marked lips. The suleus
is not fully delineated but runs from the middorsal region of the epicone posteriorly to the right
postmargin with a torsion of nearly 1.5 turns. The apical loop above the girdle extends 0.5
turn upon the epicone, the intercingular torsion is about 0.25 turn, and the antapical loop below
the posterior flagellar pore is deflected to the right, where it probably makes about 0.75 of a
turn (fig. 92,,). The whole suleal region is somewhat deeply impressed into the body. The
transverse flagellum fills the whole length of the girdle. The longitudinal one arising from the
pore at the junction of the posterior end of the girdle and the sulcus is about 0.5 transdiameter
in length.

The ocellus is of the dispersed or non-integrated type. It lies at the left of the intercingular
suleus near its posterior end and very near the posterior end of the body. Its total length is
about 0.45 transdiameter, and its axis is directed anterodextrally at an angle of about 20° from
the vertical. It consists of an elongated, segmented, hyaline lens of five appressed parts in a
linear series or loosely assembled. Posterior to these and somewhat enveloping them is a black,
amoeboid melanosome of irregular shape, which during observation spread out into branching
lobed amoeboid processes reaching from the girdle to the antapex in the peripheral plasma.
No colored core was noted.

466 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The nucleus is a broadly reniform structure in the left middorsal region. Its major and
minor axes are respectively 0.8 and 0.45 transdiameter in length. It is traversed lengthwise by
fine crowded chromatin threads. No pusules were noted. A large ochraceous food ball lies in
the center of the hypocone near the nucleus. The plasma is rosy from peripheral, anastomosing
erythrosomes which in the moribund state round up into spheres of fairly uniform size and
distribution, somewhat in lines, in the peripheral plasma which is elsewhere colorless. Among
these are found elliptical, reniform and slipper-shaped leucoplatysomes, 0.10 to 0.14 transdiameter
in length.

Schiitt’s specimens were each enclosed in a transparent, hyaline cyst somewhat larger than
the body. In the case of one of the individuals (fig. 92,.,) the eyst wall was double-contoured,
more closely applied and a second cyst wall was detaching itself on the ventral face. This
individual was evidently moribund, much rounded up as a whole with the rosy pigment of the
plasma concentrated into the so-called erythrosomes and the pigment mass of the ocellus retracted
into a compact, flattened disk. It is also probable that the lens which in figures 92, ,, is erect is
here thrown down against the contracted melanosome.

The small spherical cyst attached at the posterior end and filled with leucoplatysomes and
an erythrosome is evidently a fragment of the body eneysted separately but still adherent to
the parent plasma. The extrusion of a food ball at the posterior margin might be the cause of
such a detachment and, because of the withdrawal of substance, of the dislocation of the lens also.

Drvenstons.—Measurements of figures 92:. in parentheses. Length, 87
(70, 59); transdiameter, 54 (45, 50); length of ocellus in axis, 30 (13); diam-
eter, 10-21 (25).

OccURRENCE.—Schiitt (1895) gives no data, but his material may have come
from the Bay of Naples or have been seen on the Plankton Expedition in the
Atlantic.

Comparisons.—The possibility of two separate species being represented by
the two sets of figures (figs. 92:. and 92;..) is not excluded, but in view of the
possible abnormality of the individual represented in the first group, as above
indicated, it seems best to leave these in statu quo and base the species on the
second group of figures with the interpretation of the others as divergent or
abnormal representatives.

The species as thus defined is a member of the subgenus Pouchetia with
diffuse or non-integrated ocellus. It is, in fact, less integrated than any other
species of Pouchetia, being nearest to P. poucheti, where the pigment is scat-
tered and the lens deeply lobed. The amoeboid pigment is less markedly de-
veloped in P. subnigra (fig. OO, 6), P. alba (fig. PP, 8), P. atra (5), and P.
purpurata (3), im all of which are fine lines of granules forming a feebly de-
veloped network spreading from the central pigment mass. Segmentation of
the lens is evident also in P. alba, P. atra, and P. purpurata, in which there are
no black pigment processes, but instead scattered lines of red granules.

The lack of extreme torsion in the intercingular region of the suleus and
the diffuse structure of the ocellus are indications of a generalized or less ad-
vanced stage of development of this species, while the high differentiation of
the terminal loops of the sulcus points towards specialization.

SyvonyMy.—This species includes tentatively all of the forms figured by
Schiitt (1895) and, by implication resulting from the citations by the authors

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 467

named, of the figures both of Pouchet (1887, = P. rosea (Pouchet) and of Schiitt
(1895) only a part of P. rosea as reported by Lemmermann (1899), Pavillard
(1905), and Paulsen (1907, 1908). P. rosea Dogiel (1906) is Chytriodinium
roseum (Dogiel) Chatton (1912) and P. rosea Lohmann (1908) is P. lomanni
Paulsen (1908). P. rosea of Schroder’s (1900) reference is exclusively P.
schuetti.

Pouchetia striata sp. nov.
Text figure OO, 8

DraGcnosis.—Body rotund, length 1.2 transdiameters; girdle a descending
left spiral of 1.2 turns, displaced 0.48 transdiameter; sulcus with anterior and
posterior loops and a torsion of 1 turn; ocellus concentrated, posterior; lens
ellipsoidal; melanosome hemispherical, black with red core, color rose red; sur-
face coarsely striate. Length, 75. Pacific off La Jolla, California, August.

DescripTion.—The body has a robust habit, its length exceeding its transdiameter by only
0.2. The epicone exceeds the hypocone in length by 0.25. The epicone is broad, contracting
below the equator, with subhemispherical apex, with a length on the left of the suleus of 0.46
and on the right of 0.8 of the total length of the body. The hypocone is more contracted than
the epicone, obliquely flattened on the left side where the distal end of the suleus makes a broad
trough which extends down to the subhemispherical antapex.

The anterior junction of the girdle and suleus occurs at 0.46 of the total length of the body
from the apex. The girdle follows a descending left spiral course around the body and meets
the suleus distally at about 0.8 of the total length of the body from the apex. The furrow is
0.08 transdiameter in width and is deeply impressed with smooth, overhanging borders. The
anterior flagellar pore is located at the anterior junction of the girdle and sulcus and the posterior
pore slightly below the posterior junction.

The suleus extends anteriorly around the epicone in a wide loop which terminates at the
apex, making 0.5 turn above its anterior junction with the girdle. Below this it passes poster-
iorly at an angle of about 40° from the horizontal to meet the girdle distally, below which it
turns abruptly posterior to the antapex. It forms a wide, shallow trough with smooth borders.
Below the posterior junction of girdle and sulcus it broadens, resulting in an oblique flattening
of the left side of the antapex. There is no antapical loop.

The oecellus is 0.45 transdiameter in length, posteroventrally located at the left of the distal
end of the intercingular suleus. It is directed anterosinistrally at an angle of about 20° from
the vertical. The clear hyaline lens is ellipsoidal, about 0.35 transdiameter in length and 0.22
in diameter and has three concentric laminae. The posterior portion is imbedded in the melano-
some, which is black, hemispherical, with undulating contour, and has a red central core. |

The nucleus is large, spheroidal, and located in the anterosinistral region. Its axes are 0.56
and 0.52 transdiameter in length respectively.

The cytoplasm is very clear and transparent. Centrally located near the ocellus was a
rounded food mass and several refractive, colorless oil globules. The cytoplasm in the interior
of the body is colorless with the characteristic rose-red color of the organism concentrated in the
peripheral layer. The surface of the body is striate with a few equidistant, longitudinal, bluish
green lines, five or six across one face. These are found on both hypocone and epicone, but fade
out near the apices and girdle.

468 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Dimensions.—Length, 75+; transdiameter, 62+; axes of nucleus, 35 and 32#.

OccuRRENCE.—A single individual was taken August 21, 1917, with.a No.
25 silk net, 5 miles off La Jolla, California, in a haul from 83 meters to the
surface and in a surface temperature of 22°5 C.

JOMPARISONS.—This species is a typical member of the subgenus Pouche-
tiella with concentrated ocellus. It is close to P. voracis, but has a more highly
perfected ocellus, especially with reference to the lens. The epicone is higher,
the displacement less, and torsion greater than in P. voracis, which also lacks
the longitudinal striae characteristic of this species. The only other species in
Pouchetia with longitudinal striae are P. violescens and P. maxima, both ex-
tremely large species. P. voracis has, however, no close affinities with either of
these species. It is the most nearly spherical of all species of Pouchetia.

Pouchetia subnigra sp. nov.
Plate 6, figure 66; text figure OO, 6

DraGnosis.—Body large, ovoidal, length 1.6 transdiameters ; girdle a descend-
ing left spiral of 1.3 turns, displaced 0.6 transdiameter; sulcus with anterior
and posterior loops; torsion 1 turn; ocellus concentrated, posterior lens; elong-
ated, laminate black melanosome with brown, central core. Length, 101¢.
Pacifie off La Jolla, California, July.

Description.—This large species has an irregularly ovoidal body with its widest transdiam-
eter near the equatorial plane. The epicone is somewhat larger than the hypocone. Its apex
is broadly rounded, deeply grooved on the dorsal and left faces by the anterior loop of the sulcus.
Its length above the anterior flagellar pore is 0.2 and from its distal extremity is 0.8 of the total
length of the body. The hypocone is much narrower, approaching subconical, with rounded
antapex. This is slightly notched on the ventral face by the distal end of the sulcus.

The girdle joins the sulcus 0.3 of the total length of the body from the apex. It sweeps
around the body in a uniform descending left spiral, making 1.3 turns and meeting the sulcus
distally at a point 0.17 of the total length of the body from the antapex, giving it a displacement
of 0.6 transdiameter. The anterior flagellar pore is located at the anterior junction of the girdle
and suleus, the posterior pore near the posterior junction. The transverse flagellum traverses
0.7 of the total length of the furrow which is deeply impressed.

The sulcus invades the epicone in a wide loop, making 0.6 turn and partly encircling the
apex. It forms a broad, rather deep trough, which indents the outline of the epicone. Its lips
are smooth and rounded. After its anterior junction with the girdle it narrows to about 0.5
of its width anteriorly and proceeds posteriorly as a rather shallow trough in a depression. It
makes 0.4 turn before joining the girdle distally, after which it invades the hypocone as a short
loop which notches the ventral face of the hypocone.

The ocellus is large, 0.58 transdiameter in length, ventrally located, slightly posterior to the
equatorial plane at the left of the posterior end of the sulcus. Its axis is longitudinal and the
lens is directed anteriorly. The concentrated, laminated lens is pale bluish in color, oblong;
subovoidal, slightly asymmetrical in outline and has its base imbedded in the melanosome. The
melanosome is black with brown central core, large and irregularly rounded in outline, with
long, slender, granular, amoeboid strands extending out from it into the protoplasm. These
strands cross and form a kind of loose, open-meshed network close to the surface ventrally and
posteriorly. Other disconnected strands are found along the dorsal borders of the girdle and
of the suleus beyond the anterior flagellar pore. ;

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 469

The nucleus is large, elongated ellipsoidal, with no visible chromatin threads. It is located
near the central part of the body, its major axis nearly parallel to the major axis of the body.
Its major and minor axes are 0.88 and 0.40 transdiameter in length respectively.

The protoplasm is finely granular with no food inclusions or oil globules in the specimen
figured. No pusules were noted. The color when first observed was rose pink diffused through
the protoplasm. After some minutes under the cover glass the color collected in small globules,
as figured in plate 6, figure 66, leaving the surrounding protoplasm with a yellowish tinge. No
surface markings or striae were detected. Both individuals were enclosed in a thin, hyaline cyst
when first observed.

Drvenstons.—Lenegth, 101; transdiameter, 63¢; axes of nucleus, 50# and
284.

OccURRENCE.—Two individuals were taken July 7, 1904, with a No. 20 silk
net in a haul from 82 meters to the surface, 11 miles southwest of Point Loma,
California. Surface temperatures in July in this region range from 19° C to
Zin.@:

Actrvities.—The flagella continued to be active within the cyst during ob-
servation. Shortly before cytolysis the animal began to rotate very rapidly
within the cyst and then its diffuse, rosy pigment collected in globules regularly
distributed in the peripheral plasma.

CoMPARISONS.—This is a member of the subgenus Pouchetiella with inte-
grated ocellus, but the integration is not complete, since there is still an amoe-
hoid network of pigment. This is, however, slight in total amount, although
of wide extent, and does not seem to detract from the structural and functional
efficiency of the ocellus. The ocellus is of the elongated type with concentric
laminations. Other elongated lenses as in P. purpurata, P. schuetti, and P.
maculata are transversely segmented.

This is the largest of the species of Powchetia with posterior ocellus, and
shares with others of that group the slight development of the antapical loop
of the suleus. The large size, integrated ocellus, large apical loop and high
coloration are all indicative of the high specialization of this species.

Pouchetia violescens sp. nov.
Plate 11, figures 118, 120; text figure OO, 1

Dracnosis.—A large species; body ovoidal, length 1.8 transdiameters; girdle
a descending left spiral of 1.5 turns, displaced 0.66 transdiameters; sulcus with
apical and antapical loops with torsion of 3 turns; ocellus of concentrated lens
and black pigment with lighter core; color, violet. Length, 1154. Pacific off
La Jolla, California, June, July.

DeEscripTion.—This is a large species with stout, ovoidal body, with its widest transdiameter
at the proximal base of the epicone somewhat anterior to the middle of the body. The epicone
greatly exceeds the hypocone in both length and volume. The epicone is long and domelike
with rounded apex notched by the anterior loop of the sulcus. Its length above the anterior
flagellar pore is 0.4 and from its distal end is 0.8 of the total length of the body. Below the
anterior pore it narrows down to a point in 1.5 turns. The hypocone is narrower than the
epicone and has the shape of a truncated cone of about 75°. It is deeply excavated in the region
of the lens, and its antapex is obliquely truncated.

470 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The girdle joins the suleus at a point distant from the apex 0.4 of the total length ef the
body. It sweeps around the body in a descending left spiral and after 1.5 turns meets the girdle
0.2 of the total length of the body from the antapex. It oceupies a broad, deep depression with
smoothly rounded borders. The anterior flagellar pore is situated at the point of its anterior
junction with the suleus and the posterior pore slightly below the posterior junction on the
opposite face of the body from the anterior pore. The transverse flagellum traverses about 0.5
of its length. In figure 118, plate 11, the flagellum was inverted and oceupied the anterior
portion of the suleus. In figure 120 and text figure OO, 1, it is found oceupying its normal
position on the girdle.

The suleus invades the epicone in a wide loop of 1.5 turns above the anterior junction with
the girdle. It passes once around the body and then turns upward and abruptly to the left,
ending on the apex which it notches. Below the anterior pore it turns in a descending left
spiral course, making 0.5 turn before meeting the distal end of the girdle. Beyond this it makes
one complete turn around the antapex, ending on the left side. The suleus occupies a rather
broad and deep channel throughout its course except where passing over the ocellus below the
anterior pore. Here it becomes somewhat obscured by the projecting body of the pigment mass.

The ocellus is large and situated immediately below the proximal part of the girdle near the
middle of the body and on the left of the suleus, and is directed dorsoventrally or postero-
anteriorly. Its length is 0.42 transdiameter and its axis is subhorizontal, raised 20° above the
horizontal and pointed to the left in one specimen (pl. 11, fig. 118) and deflected posteriorly an
equal amount or more in a second (moribund) individual. The lens is large, spherical, with
concentric laminae of a clear, hyaline material. It is slightly imbedded in the pigment mass.
The melanosome is generally larger than the lens, actively amoeboid and black in color with a
lighter central core. In figure 118, plate 11, the hghter central core is seen emerging from the
black pigment mass as a large clear body just above the mass of pigment which is here rounded
up, and pressing close against the lens. In this same figure the line of suleus across this region
is not shown and one small are of the outer wall of the lens is omitted by oversight. In text figure
OO, 1, the details of this area are complete. In figure 120, plate 11, another individual is shown
in which the amoeboid melanosome has moved farther anteriorly around the lens. Since this
is seen here from the melanosome end its length is foreshortened and the relations of lens and
melanosome somewhat obscured.

The nucleus is large, spheroidal and is located in the anterior half of the body. About
thirty-five fine parallel beaded chromatin threads traverse it obliquely. Its diameter is 0.27
transdiameter of the body. A large, bifureating pusule filled with pinkish fluid passes into the
center of the body from the anterior flagellar pore and a smaller sacklike one trends posteriorly
from the same region. On one face six to eight nearly equidistant striae, interrupted by the
ocellus, are found in the peripheral plasma.

The cytoplasm is very clear and transparent. A few refractive oil drops and a single large,
ochraceous food mass were found close behind the ocellus in figure 118. A few minute, bluish
green oil droplets were scattered through the peripheral plasma. The color is a clear, light
violet, diffused somewhat uniformly throughout the peripheral zone of cytoplasm. The indi-
vidual drawn in figure 120, plate 11, showed the same diffuse distribution of the color as in
figure 118 when first observed. After being kept under the cover glass for nearly one hour the
color began to condense into small granules and longitudinal lines, especially along the girdle,
which formed a mesh over parts of the body, leaving the remainder colorless. These lines of
pigment appeared strikingly amoeboid in their movements, changing quite rapidly during the
time required for a camera sketch. The same change took place in the first individual before
cytolysis occurred.

Dimensions.—Length, 106-115; transdiameter, 51-63; diameter of nucleus,
16-184.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 471

OccuRRENCE.—This species was first taken 2 miles off La Jolla, California,
on July 3, 1906, with a No. 20 silk net in a haul from 155 meters to the surface.
Two individuals were taken July 16, 1917, in a surface haul at the end of the
pier at the Biological Station at La Jolla in a surface temperature of 21°5 C.

ACTIVITIES.—Ohe individual moved slowly without rotation in anticlockwise
circles about twice the length of the body in diameter. The movements of the
pigment, prior to cytolysis, in streams along the girdle and sulcus and in the
longitudinal lines coincident with or parallel to the longitudinal striae is sug-
gestive of an intimate relationship between locomotor organs and the metabolic
processes concerned in the formation and distribution of pigment.

CoMPARISONS.—This species is close to Pouchetia juno Schitt in size, median
location, and horizontal axis of the ocellus as well as in its structure. The
differences le in the striae of P. violescens, which are not recorded for P. juno,
which has, moreover, peripheral ringlike platysomes not present in P. violes-
cens. hese are superficial characters, easily overlooked and possibly, in the
case of platysomes, evanescent. The structure of the girdle and sulcus, how-
ever, is different in the two species. The anterior flagellar pore in P. juno is
0.3 of the total length from the anterior end, while in P. violescens it is 0.45
with a corresponding increase in the length and torsion of the apical loop of
the sulcus.

P. violescens is a typical member of the subgenus Pouchetiella and with
P. polyphemus and P. juno forms a group of large species with median ocellus.
A similar group of large species in the subgenus Pouchetia sensu strictu includes
P. maxima, P. voracis, and P. fusus, in all of which the lens is lobed or sub-
divided. |

P. vielescens is the only violet species thus far known among the Gymno-
dinioidae. Pale glaucous bluish colors are rather common and a darker blue
is known in Gymnodinium coeruleum. It is also the only species in Pouchetia
which is noticeably striate, the nearest approach to striations appearing in
P. maxima and P. striata.

Pouchetia voracis sp. nov.
Plate 8, figure 89; text figure PP, 2

DrAcnosis.—Large species with rotund body, its length 1.3 transdiameters ;
girdle with 1.25 turns around body, displaced 0.4 total length; sulcus with torsion
of 0.5 turn; ocellus concentrated, median; lens elongated, lobed; pigment mass
with black, amoeboid melanosome with red central core; core, spinel red.
Length, 68+. Pacific off La Jolla, California, July, August.

Description.—The body is large, rotund, broadly ovoidal in contour, with the epicone and
hypocone subequal. The epicone presents a large, hemispherical apex. Its length is 0.3 above
the anterior flagellar pore and at its distal extremity, 0.8 of the total length of the body. The
measurements of the hypocone are somewhat smaller, being anteriorly 0.7 and posteriorly 0.2

472 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

of the total length of the body in length. The antapex is rounded, asymmetrical, longer upon
the right side, the deep channel of the distal end of the suleus forming a broad trough, deeply
furrowing its left ventral face and slightly notching the antapical margin.

The junction of the girdle and the suleus occurs at a distance of 0.3 of the total length of the
body from the apex. Thence the furrow sweeps around the body in a uniformly descending
left spiral of 1.25 turns as a broad, rather deep trough, its width being 0.07 transdiameter. In
an individual which had devoured a theeate Peridinium (fig. PP, 2) the girdle is distorted so
that it steepens rapidly in the proximal half to 50° from the horizontal, flattens again almost
to the horizontal middorsally, and then descends gently at 20° to its posterior junction with the
suleus. This occurs at 0.25 of the total length from the antapex. The sulcus takes origin at or
very near the apex. It sweeps 0.25 turn around the epicone to its anterior junction with the
girdle. It forms a deep trough in its posterior course, with a total torsion of 0.5 turn of a
descending left spiral, and widens below its distal junction with the girdle to twice its width
above. Below the junction it curves across the hypocone to the antapex, notching its postmargin
slightly. The lips of both girdle and suleus form prominent, slightly overhanging ridges,
especially anteriorly. The anterior flagellar pore is found at the proximal junction of the
girdle and sulcus, the posterior one slightly beyond its distal junction. The transverse flagellum
traverses about 0.5 the entire length of the girdle.

The ocellus is of the concentrated type and is situated in a midventral position on the left
side of the suleus. Its length is 0.45 to 0.60 transdiameter and its main axis is horizontal and
directed ventrally in one individual (pl. 8, fig. 89) and vertically with an anterior direction in
another (fig. PP, 2). The direction of both is probably affected by the presence of adjacent
food bodies. The lens is of the concentrated type, elongated, smooth or slightly lobed in outline,
where crowded upon a food mass (fig. PP, 2) of a dull, opaline-green color, and showing faintly
outlined concentric layers. The base is more or less deeply imbedded in the large, amoeboid
melanosome which at times almost covers it, then retreats, leaving it exposed for nearly its entire
length. The central core is large and searlet red to maroon in color. A few large granules of
black or red pigment are found in the peripheral cytoplasm near the girdle.

The nucleus is large, ellipsoidal, and located in the anterosinistral region. Its major and
minor axes are 0.65 and 0.5 transdiameter in length respectively. Distinet parallel, crowded,
chromatin strands pass obliquely across its main axis.

A small, club-shaped pusule opens into the anterior and another into the posterior flagellar
pore, each with its apex directed towards the equatorial plane.

Pouchetia voracis, like many of the Gymnodiniidae, is a voracious feeder. In one individual
(fig. PP, 2) the still connected but collapsed theea of a large Peridinium, resembling P. crassipes,
was found crowded into the posterosinistral region, and pushing the ocellus against the suleus.
The contents had apparently been digested, leaving only the shell, the plates of which were
becoming displaced, as though by pressure. These plates still preserved many of their charac-
teristic markings, as if unaffected by the digestive processes. The whole mass was enclosed in
a large food vacuole. Along the ventral side of the body were a row of blue-green peripheral
rodlets, all at right angles, or nearly so, to the surface. These rodlets were not present in the
other individuals figured (pl. 8, fig. 89), and are evidently correlated with the metabolism
ensuing upon digestion. In a second individual small food masses, one ochraceous, were crowded
between nucleus and ocellus. The cytoplasm is clear and very finely granular with a few oil
drops centrally located. There were no peripheral vacuoles present.

The color, which is a clear spinel red, is concentrated in a thin peripheral layer, immediately
underneath the periplast, leaving the inner protoplasm quite clear. In some eases the border of
the girdle shows a narrow, blue-green line.

A large, thin, hyaline cyst enclosed the individual figured, inside of which was a second,
smaller one of the same appearance. These were both ellipsoidal in form and more widely
detached anteriorly and ventrally than posteriorly and dorsally. The second individual was

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 473

also encysted and had external thickenings of the cyst wall about the apex above the apical loop
of the suleus and along the girdle, indicating greater secretory activity anteriorly and along the
motor region.

DiMeEnstons.—Length, 68-80; transdiameter, 50-67“; major and minor axes
of nucleus, 37-42» and 20-25; ocellus, major axis, 21—26v.

OccuRRENCE.—The first specimen was taken from a haul made on July 27,
1917, 4 miles off La Jolla, California, with a No. 25 silk net from a depth of
80 meters to the surface, in a surface temperature of 21°9 C. Another from
a haul August 17, 0.75 mile off La Jolla, at a depth of 80 meters to the surface,
in a surface temperature of about 22° C.

ACTIVITIES.—One individual was kept under observation from 2 p.m. to 3
p.M., when cytolysis ensued. It was encysted and inactive, but when the slide
was tapped it rotated a few turns within the cyst. When rolled over by moving
the cover glass it always returned to the same position as though passively by
gravity.

Unimpeachable evidence of the holozoic nutrition of this species is presented
by the remains of the component plates of the theca of a large Peridiniwm
within a food vacuole of an encysted individual of this species. Its contents
had been almost completely digested. The manner in which a Pouchetia, with
an almost labile protoplasmic body, devoid of protrusible food-grasping organs,
can capture, hold, and engulf a Peridiniwm, more than half its size, passes com-
prehension. From the location of the Peridinium in the body of its captor it
seems probable that it was taken in through the sulcus below the anterior
flagellar pore and the posterior end of the body, that is, mainly through the
intercingular suleus. A mobility of this region sufficient to capture a mobile
Peridinium and ingest its rotund body with protruding apical and antapical
regions requires an efficiency of function quite beyond that suggested by the
structure of these regions of Pouchetia, and exceeds, to a high degree, our pre-
conceptions as to the instincts, reactions, and capacities of these unicellular
organisms.

JOMPARISONS.—This is one of the least specialized species of the subgenus
Pouchetiella with concentrated ocellus. Its lens, when in juxtaposition with a
food mass, 1s slightly lobed, its melanosome is irregular if not slightly lobed,
and detached globules of red or black pigment are found near the girdle. The
integration of lens and pigment is well established, but the position of the ocellus
is shifted by the pressure of food masses.

Pouchetia voracis is close to P. striata, but is less rotund, more asymmetrical
posteriorly, has a shorter apical sulcus, and proximal epicone with less torsion,
and less intercingular displacement of the girdle. The ocellus has a slightly
more anterior position and similar structure, but is less distinctly laminate.
It also lacks entirely the longitudinal striations characteristic of P. striata.

CHAPTER XX

POUCHETIIDAE (continued): PROTERYTHROPSIS, ERYTHROPSIS
SUMMARY

PROTERYTHROPSIS gen. noy.
Text figure PP, 9

DraGnosis.—Pouchetiidae with median girdle, posterior ocellus, stout rudi-
mentary tentacle or prodlike antapical process, with no paracingular lines and
no recess about the base of the prod. Type species Proterythropsis crassicau-
data sp. nov.

Discussion

This genus includes only a single species whose structure is such that it
is excluded on the one hand from Pouchetia and on the other hand from
Erythropsis. It is a typical Pouchetia in all features except in the presence
of the posterior prod. The presence of longitudinal rows of pigment granules
is also somewhat unique for Pouchetia, within which the linear organization
of the peripheral plasma in any fashion is rarely evident, appearing as striae
only in P. striata, P. maxima, and P. violescens and as pigment granules with
the merest trace of linear arrangement in P. maculata. In the one species
known in Proterythropsis there is a well defined but locally restricted expression
of this linear organization in the arrangement of the peripheral spherules of
pigment.

It is excluded from Pouchetia, however, by the presence of a posterior prod
not unlike those of Hrythropsis, except in size, slight development, and absence
of a recess about its base. It is excluded from Erythropsis, however, not only
by this lack but also by the arrangement of girdle and sulcus, which is quite
typical of that in Pouchetia, and also by the entire absence of anything sug-
gestive of the paracingular lines which parallel the girdle. In view then of the
absence of the recess, flattened epicone with apical horn, and paracingular lines,
it is impossible to include the species in Hrythropsis. In view of the fact that
it affords a transition in structure looking towards the genus Erythropsis from
the types evolved in Pouchetia, the new genus Proterythropsis has been estab-
lished to receive it. The nature of its most characteristic structure, the postero-
ventral prod, is unfortunately not well established or fully described owing to
the mobility of the organ and of the organism carrying it. In so far as position,
direction, morphological relations, and activities are concerned, it appears to be
the same organ as the prod of Erythropsis, only in an initial stage of evolution.

[474]

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 475

Its primitive or generalized stage is indicated by the absence of recess, of
terminal stylet, lack of development of circular and longitudinal contractile
fibers, the protractor and retractor muscles, and of a capitate end. The ventro-
posterior direction is perhaps less advanced than the posterior direction seen
in all species of Hrythropsis except EF. protrudens, in which the direction of the
prod is the same as in Proterythropsis.

That we have in this genus a connecting link between Pouchetia and Ery-
thropsis is further supported by the fact that the posterior end of Pouchetia,
in some species with the antapical loop of the sulcus twisted about that part
of the hypocone below the distal end of the girdle, is highly mobile in life, and,
as we have observed in several such species, somewhat protrusible, though it
never forms a permanent prod. In this connection it is well to recall the fact
that the prod of Erythropsis is subject to remarkable changes in shape and
extension.

The nucleus, with moniliform chromatin threads, is of the Pouchetia type,
rather than that of Erythropsis, which is remarkably clear in life and often
has a perinuclear clear zone.

Only one species, the type, Proterythropsis crassicaudata, is known in this
genus.

Proterythropsis crassicaudata sp. nov.
Plate 11, figure 123; text figure PP, 9

Dracnosts.—A medium sized species, ellipsoidal, length 1.4 transdiameters ;
girdle a descending left spiral of 1.2 turns, displaced 0.8 transdiameter ; sulcus
of 0.3 turn; ocellus of distributed type, posterior, with elongate segmented lens
and reddish-black pigment mass and red central core ; stout tentacle-like ventro-
posterior process. Length, 70e. Pacific off La Jolla, California, July.

DeEsScRIPTION.—The body is asymmetrically ovoidal, widest just below the anterior postero-
ventral receding face; the outline broken by a tentacle-like process projecting ventroposteriorly.
The epicone equals the hypocone in length but exceeds it considerably in volume. It is broad,
hemispherical at the apex, with a length above the anterior flagellar pore of 0.25 and from its
distal extremity of 0.7 the total length of the body. The hypocone bulges out ventrally below
the proximal end of the girdle, is deeply grooved above the suleus and the whole ventral face
recedes posterodorsally about 25° from the vertical. The antapex is then pushed dorsally. It is
asymmetrically hemispheroidal, without suleal notch.

The girdle meets the suleus anteriorly at a point 0.25 of the total length of the body from
the apex. It sweeps around the body in a descending left spiral of 1.2 turns before joining the
sulcus again at a point 0.18 of the total length of the body from the antapex. Its total displace-
ment is thus 0.57 of the total length. It lies in a broad, deep trough, the margins of which bulge
outward in high ridges. Its width is 0.08 transdiameter, its anterior hp overhangs, and it is
deeply impressed. The anterior flagellar pore is located at the anterior junction of girdle and
sulcus and the posterior one at the distal junction. The transverse flagellum traverses only 0.2
of its total length, probably foreshortened as cytolysis approaches. The stout longitudinal
flagellum may be coiled about the prod.

476 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The sulcus invades the epicone but a short distance beyond the anterior flagellar pore as a
shallow trough. Below this point it descends posteriorly as a slender channel in a deep trough,
whose borders form high ridges on either side. Beyond the distal junction of the girdle and
sulcus it traverses the hypocone but a short distance as a shallow channel. Its total torsion is
only 0.3 turn, but the apical section may be incompletely delineated.

The ocellus is located in the ventral region close to the posterior flagellar pore and to the
left of the suleus. Its length is 0.5 transdiameter and it is directed anteroventrally about 45°
from the vertical. The lens is oblong, somewhat elaviform, and is composed of four unequal,
hyaline, coiorless spheroidal or ellipsoidal moieties, closely pressed together in a linear series
decreasing in size towards the melanosome. Its base is imbedded in the amoeboid pigment
mass. The greater part of this is rose red in color, with a smaller mass of black pigment on the
ventral side. The central core is red.

The nucleus is large, ovoidal, and anteriorly placed in the ventral part of the epicone.
Chromatin strands follow the course of its major axis. Its major and minor axes are 0.8 and
0.4 transdiameter respectively in length.

A large club-shaped pusule opens anteriorly into its anterior flagellar pore. The posterior
one was not observed. The cytoplasm is rather coarsely granular and clear with a few large,
bluish vacuoles in the anterior region. Two dark olive buff food bodies were present posteriorly.
On the dorsal side of the body, peripherally located, are many rufous colored granules, gathered
near the girdle and extending anteriorly in longitudinal rows, about eight in number, in the
peripheral plasma to near the apex. Rod-shaped masses of the same rufous material are found
along the proximal border of the girdle in the posterior region. On the opposite side from the
ocellus are several subparallel rows of granules and several larger spherules of the same rufous
material. No surface markings or striations were present.

The color is a light, dull yellow mixed with grey and distributed quite uniformly through
the cytoplasm.

The most remarkable organ of this animal is the contractile prod which emerges from the
widened suleus just below the distal end of the girdle and hangs pendant ventroposteriorly at
about 45° from the horizontal in its basal part, then curves posteriorly. In form it is a eurved
cone with rounded apex. Its length and basal diameters are 0.50 and 0.24 transdiameter respec-
tively and the angle of the core is approximately 25° when the prod is extended. When con-
tracted it merges somewhat basally with the ventral face of the hypocone. The recession of the
ventral face of the hypocone is apparently correlated with the development of this protrusion
and the consequent withdrawal of the material from this region utilized in its formation. The
cavity about the base is so sight as not to merit the designation of a recess such as occurs in
Erythropsis.

Divensions.—Length, 70; transdiameter, 49+; axes of nucleus, 291 and 19;
length of ocellus, 20; length of fully extended prod, 25.

OccURRENCE.—A single individual was taken July 25, 1917, 11 miles off La
Jolla, California, with a No. 25 silk net in a haul from 80 meters to the surface,
in a surface temperature of 21°7 C.

Activitres.—The animal progresses by rotation and circling in anticlockwise
spirals several times its length in diameter and when quiescent the prod is seen
to undergo somewhat spasmodic contractions. They are not repeated as regu-
larly and rapidly, nor are its excursions so extended as in Erythropsis.

Comparisons.—The median location and the displacement of the girdle are
not unlike that seen in Pouchetia striata and P. voracis, and the structure of
the ocellus is quite similar to that of P. maculata, although the pigment has less

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 477

melanin. The torsion of the body, as shown by the course of the suleus, is only
0.2 turn, far less than in any species of Pouchetia, and thus more like that of
Erythropsis. The stout longitudinal flagellum recalls that figured by Schiitt
(1895) for Pouchetia cornuta (= Erythropsis cornuta).

ERYTHROPSIS Hertwig
Plate 12, text figures RR-VV
““ Acineten’’ Metechnikoff (1872), pp. 7-9; (1885), p. 433.
Erythropsis Hertwig (1884), pp. 204-212, pl. 6.
Spastostyla, Vogt (1885a@), in part, p. 53; (18856), pp. 183-187, fig. 1.
Pouchetia, Sehiitt (1895), in part, pl. 26, figs. 95, 96.
Erythropsts, Delage and Hérouard (1904), pp. 887-888, figs. 680, 681.

DIAGNOSIS

Gymnodinioidae with flattened epicone less than 0.25 the size of the hypo-
cone, flattened anteriorly and with or without a small curved apical horn.
Ocellus very large, composed of one or several hyaline lenses attached to or

OSL pat
tentneCy =a

Fig. RR. 1. Erythropsis cornuta (Schiitt). 2. 2. scarlatina sp. nov. Abbreviations: ant. p., antapieal pore;
ap. h., apieal horn; ap. l., apical loop; core, core of melanosome; epi., epicone; fur., furrow; gir., girdle; hyp.,
hypocone; l., lens; mel., melanosome; n., nucleus; 0., ocellus; pig., pigment; post. p., posterior pore; post. par. l.,
postcingular paradinial lines; pre. par. l., precingular paradinial lines; prod, prod or tentacle; pus., pusule;
retrac. fib., retractor fibrillae; sule., suleus; sty., stylet; tent. rec., recess of prod or tentacle; tr. fl., transverse
flagellum. X 500.

imbedded in the side of a red, brownish or black pigment body with a red,
brown, or yellow core, located to the left of the intercingular sulcus. The girdle
makes a single, descending sinistral turn and may be bordered by the precing-
ular and postcingular grooves which we designate as the paracingular grooves
or lines. The suleus expands posteriorly into a ventroposterior tentacular
recess from the center of which springs a posteroventrally or posteriorly

478 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

directed tentacle or prod which in several species attains a length twice that
of the body and is subject to incessant rhythmical contractions. It may or may
not have a capitate end and a terminal stylet. An attachment area may be
found at the distal end of the girdle. The form is somewhat rigid and the
surface almost differentiated into a distinct pellicle, mottled by vacuoles as
cytolysis approaches. No striae are present. Anterior pusule attached to the
anterior flagellar pore and another to the tentacular recess. Posterior longi-
tudinal fiagellum probably present in addition to tentacle, but evanescent or
easily. lost. A single ellipsoidal nucleus present. The chromatin network not
distinct in life. Perinuclear zone with vacuoles and envelope are sometimes
present. No chromatophores. Pigment usually confined to the ocellus, dis-
tributed as a network of scarlet in one species. Plasma homogenous and trans-
lucent. Nutrition evidently holozoic. Binary fission not observed. Autotomy
of tentacle and cytolysis occur on slight stimulus.

All small, marine species 48-130 in length. Ten species known from warm
temperate and tropical seas.

DESCRIPTION

The form of the body in Erythropsis is highly specialized, due to the invasion
of the hypocone by the ventral recess (fig. RR, tent. rec.), the foreshortening
of the epicone, and its apical flattening. This form appears to have been
brought about by a reversion from a condition of greater torsion, so that the
sulcus, instead of having a considerable obliquity in the intercingular area, as
in Pouchetia, has, in Erythropsis, an almost straight course in this section, and
the distal end of the girdle in compensation is deflected abruptly posteriorly
in the distal 0.15 or so of its course. The result of this reduction in torsion
is apparent in the almost horizontal course of most of the girdle, its marked
distal deflection, and the straight intercingular sulcus. Accompanying these
modifications of the girdle and sulcus, and possibly the prime cause of their
origin, is the considerable increase in relative size of the ocellus and its anterior
location. The ventral recess is a deep excavation opening ventroposteriorly
and sheltering the basal end of the prod. Ventrally it is the continuation of
the sulcus and posteriorly it is terminal and even axial. It also contains the
opening of the posterior pusule, the posterior flagellar pore, and the posterior
flagellum. It is thus the deeply recessed posterior end of the sulcus.

The ocellus of Hrythropsis is in all cases premedian, often far anterior,
usually protuberant, directed anteriorly, never horizontally or posteriorly. It
is also relatively very much larger than in Pouchetia. It is present in both the
diffuse type (subgenus Polyopsidella) and the integrated subgenus Hrythropsis.
The integrated forms attain a high degree of specialization, as in EL. cornuta,
E. protrudens, and E. pavillardi. It is a matter of note, as indicating that the
whole organism shares this specialization, that it is in these same species that
the paracingular lines and the prod are also highly developed. The presence

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 479

of a pigmented sensory core is a prominent feature in the integrated type of
ocellus. The structural and morphological evidence is strong that the ocellus
of Erythropsis is functionally the most efficient optical organ among the Dino-
flagellata and the Protozoa as a whole.

The ‘‘tentacle’’ (Hertwig, 1884), or dart (‘‘dard,’’ Fauré-Fremiet, 1914),
or prod as we designate it (fig. RR, prod), is located ventrally in FL. extrudens
or ventroposteriorly in EL. minor and FL. scarlatina, and posteriorly and axially
in the remaining species. It may be capitate, as in LH. labrum, HE. pavillardi, and
E., extrudens, or lack distal enlargement as in the other species. It may have
a terminal stylet, as in EL. hispida, HF. extrudens, and E. cornuta, or lack this,
as in other species. It has an axial, longitudinal, contractile group of fibers, the
retractor fibrillae (fig. RR, retrac. fib.), and a series of circular ones, the pro-
tractors. These antagonistic groups give to the organ an extraordinary degree
of mobility and render possible the extension of this organ to a length four times
that of the body. The operation of a Lamarckian factor of activity of this
organ in the origin of the ventral recess about its base and in the pushing of the
ocellus far anterior is suggested by the structural features of the genus. One
who has watched this organ in action has its potency strongly intimated to him.

The occasional persistence of the longitudinal flagellum alongside this organ
precludes any possibility that it is a modified posterior longitudinal flagellum.
It appears rather to be a mobile margin of the sulcus specialized as an axial
organ, as foreshadowed in the prod of Proterythropsis and the mobile antapex
of Pouchetia and Cochlodinium.

The paracingular lines which border the girdle on both sides in EF. cornuta,
E. richardi, E. labrum, and E. extrudens (fig. RR, pre. par. l., post. par. l.), and
may have been wholly or in part overlooked in the other species, are faint
modifications of the surface pellicle, or even slight modifications of the contours
which run parallel to the margins of the girdle throughout its whole course.
Their functional significance is wholly obscure and their homology quite prob-
lematical. The nearest approach to anything lke them in the Dinoflagellata
are the precingular and postcingular series of plates in the theeate forms. But
there can be no possibility of the origin of such rows of plates from these para-
cingular areas. The similarity of the relationship of the paracingular lines on
the one hand and the rows of plates on the other to the girdle suggests the func-
tion of the latter in influencing, if not originating, such organs.

The presence of huge melanosomes and of the red pigment in the plasma
of EF. scarlatina and in the sensory core of the ocellus of most species, and in
the entire pigment mass of F. agilis, establishes the predominance of the red
end of the spectral colors in this genus, thus continuing the same relationship
of these pigment colors to specialization which was detected in the genus
Pouchetia.

No chromatophores are present. No food balls have been detected, but it is
probable that the species are holozoic, as is Pouchetia.

480 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

«|

9290020

Fig. SS. Erythropsis Hertwig. Magnification 500, unless otherwise stated. 1. E. cornuta (Schiitt). Ven-
tral view. 2. E. hispida sp. nov. Ventral view. 3. EZ. pavillardi nom. sp. nov. Left side. 4. EH. scarlatina
sp. nov. Ventral view. 5. EZ. pavillardi nom. sp. nov. Right side. After Pavillard (1905, pl. 3, fig. 1). 6.
E. labrum sp. noy. Ventral view. 7. HE. cochlea (Schiitt). Dorsal view. After Schiitt (1895, pl. 26, fig. 95).
8. E. agilis Hertwig (1884, pl. 6, fig. 8). Ventral view. X 250, approximately. Girdles and sulcus not shown
in original figure. 9. E. minor sp. nov., ventral view. 10. EZ. richardi sp. nov. Ventral view. 11. E. extrudens
sp. nov. Right side. 12. 2. agilis Hertwig. Ventral view. After Hertwig (1884, pl. 6, fig. 1). Magnification
approximated from statement of lenses used.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 481

The genus Hrythropsis is the most highly specialized of all the Gymnodi-
nioidae as shown in accessory paracingular grooves along the girdle, the apical
horn, the ocellus, and the complete integration of its constituent lens and pig-
ment mass and in the prod with its functional specialization. The ocellus and
prod alike attain a degree of structural complexity and diversity in the genus
unequaled among all of the Protozoa. As an organ adapted in structure to
the performance of specific function the ocellus is of the same order of magni-
tude, though not of dimensions and cellular components, as the ocelli of the
Hydromedusae, Turbellaria, and Rotifera, and the tentacle or prod is in like
manner structurally comparable to those of the simpler Hydroida, though not
their equivalent in function. The organization of the living substance into
organs ‘for bodily functions is evidently, in the light of these extraordinary
structures of this unicellular organism, not a function of the number of nuclei,
but rather of the organism as a whole. The cell theory as a basis of organization
breaks down when we attempt to apply it to the organs of the Protozoa.

DISTRIBUTION

The species of Hrythropsis thus far discovered have all been found in warm
temperate to subtropical oceanic seas under strikingly similar conditions. The
eight species discovered at San Diego, in the summer of 1917, were all taken
within a period of three weeks and at the same locality. In some instances
several species were taken in the same five-inch net. We have found no evidence
of either seasonal or geographical isolation of these species. The possibility of
a vertical stratification within the eighty meters traversed by our collecting nets
is, however, not excluded by our data, but seems highly improbable.

HisroricaL Discussion

The history of this remarkable genus is as complicated as its own extraor-
dinary combination of organs, and involves one of the most instructive contro-
versies in the history of the biological sciences in the past century. It illustrates,
on the one hand, the value of the scientific caution of the original describer,
and, on the other, the recklessness of his critic and the resulting depth of error
into which his unbridled zeal for exposure carries him when, without having
seen the object under discussion, he ventures to discredit the work of another.

The genus was described by Professor Richard Hertwig (1884), who found
a single individual in the plankton of the Mediterranean at Sorrento, Italy, in
the Kaster vacation. Upon placing it under the cover glass for examination it
dropped off its tentacle, whereupon it was at once fixed in osmic acid and stained
and mounted. Professor Hertwig’s account of this remarkable organism was
therefore based upon his recollection of a brief glimpse of the active animal
under a low magnification and a closer study of its mutilated and somewhat
distorted remains. His conclusions, as to the relationship of this bizarre animal,
were that it was undoubtedly a protozoan and one of the Infusoria, although

482 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

he noted that, in the possession of an eyespot composed of a pigment mass and
a lens, and in the presence of a highly contractile ‘‘tentacle,’’ the degree of
organization presented by the organism was unusual for the Protozoa. Hert-
wig (1884) did not attempt to determine the relationships of his Hrythropsis,
but suggested that it was near the Infusoria and that its cuticula, nucleus, and
opercular apparaus allied it to the vorticellid, but that the characterisic cilia
of these ciliates had not been observed in his new genus. He makes no suggestion
of any relation of Erythropsis to the Dinoflagellata, though he does cite Lepto-
discus and Noctiluca in discussing the question of its degree of specialization.

Shortly after the appearance of this cautiously worded account of this weird
protozoan by the young docent at Bonn the veteran zoologist, Carl Vogt, of
Geneva, attacked (1885a) with characteristic vigor the validity of Hertwig’s
interpretation. He requested his colleagues to debar Hrythropsis from the
‘catalogue’? of animals and stated dogmatically that it was ‘‘in der That”’
only a detached vorticellid, Spastostyla sertulariarum Entz, which had had the
misfortune to have been thrown into osmic acid by the Bonn zoologist just as
it was in the act of swallowing a marginal eyespot of a half rotten medusa,
probably Lizzva.

Hertwig (1885) published a reply to this attack upon his interpretation
stating his grounds for believing that Hrythropsis was a real organism and
not the monstrous aggregation which Vogt had interpreted it to be. Vogt,
however, returned to the attack (1885b) in a caustic article entitled ‘‘ Ein
wissenschaftlicher Irrthum,’’ published in the widely distributed Die Natur,
a popular scientific journal, in which he made clear his duty to expose the error,
the grounds upon which the exposure rested, and controverted Hertwig’s reply,
treating him anonymously. ‘‘Der Mensch irrt, so lange er lebt,’’ writes Vogt,
and then proceeds to distinguish, as particularly harmful to science, those errors
in fact, such as false accounts of organisms which cumber synonymy, and give
rise to unsupported hypothesis.

Ein neuer Organismus wird beschrieben, dessen ganzer Bau, wenn er wirklich existirte,
unsere Begriffe von der thierischen Zelle, von den einzelligen Urthieren mit Allem, was drum
und dran hingt, giinzlich iiber den Haufen werfen wiirde. Was ist zu thun? Schweigt man
still, so zieht die unerwartete Thatsache stets weitere und weitere Kreise. Die jiingeren
Forscher, meist wenig zur Kritik geneigt und dem Worte des Meisters treu, machen aus dem
neuen Steine die Grundlage ihrer Spekulationen und theoretischen Gebiude; es erdffnen sich
groszartige Perspektiven; man sieht schon weitere Verzweigungen und Ankniipfungen der jetzt
so beliebten Stammbiiume, die ohne Riicksicht auf Zeit und Raum zusammen geflickt werden,
wie die Stammbiiume der Paladine, die alle von fliichtigen trojanischen Helden ausgingen. So
gibt man sich, neben den vergeblichen Nachforschungen um weitere Exemplare des so hoch
interessanten und merkwiirdigen Thieres, viel Miihe, Noth und Plage, bis endlich die Seifenblase
platzt, welche dem Ganzen zu Grunde lag.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 483

He then descends to doggerel:

Was man in Osmium besitzt,
Kann man bequem nach Hause tragen!

_ Und wenn man d’ran gezeichnet und geschwitzt,
Auch manches Schone d’riiber sagen.

and erects the deadly parallel column in the form of comparative figures of
“Hrythrypsis agilis; nach R. Hertwig”’ and “‘Spastostyla sertulariarun; nach
Geza Entz.”’

The impartial observer’s estimate of the fairness of the critic’s attack must
be influenced by the fact that the figure of Krythropsis agilis which Vogt states
is ‘nach R. Hertwig’’ is not a reproduction of any of Hertwig’s (1884) figures,
but is a highly modified combination of Hertwig’s figures 2 and 8. The modi-
fications are: (1) the elongation, curvature, and narrowing down of the nucleus
in the direction of the vorticellid type of nucleus; (2) the change of the con-
tinuous spiral (as Hertwig had drawn it) into an adoral zone of separated
membranelles, as a sheath containing a fibrillar axis as in Vorticella instead
of a homogeneous solid cylinder as distinctly figured by Hertwig.

With this deadly parallel before his readers, Vogt proceeds to demonstrate
that, part for part, Hertwig’s Erythropsis is nothing but a Vorticella, its ten-
tacle being the stalk of the ciliate while the eve is that of a medusa lodged in
the gullet of the Vorticella fixed at the instant of swallowing. To add poignancy
to the thrusts of his criticisms he further illuminates the enormity of the error
by publishing ‘‘nach den Briidern Hertwig”’ figures of the ocelli of Lizzia and
Nausithoe, whose similarity to the pigment spot and lens of Hrythropsis, as
Vogt figures them, is little less than damning.

In extenuation of Vogt’s conclusions it is to be noted that the dimensions,
which may be approximated from the recorded systems of objectives and oculars
used in making the figures of Hrythropsis, and the ocellus of Lizzia, are such
that such a combination of eyespot and Vorticella is spatially possible, and
furthermore that Hertwig’s figures (1878, pl. 8, figs. 9, 10) of the ocellus of
Lizzia and that of the lens and pigment mass of Hrythropsis have much in
common in appearance, though structurally entirely different, as Hertwig
(1885) had shown. Hertwig’s figure (1884, pl. 6, fig. 7) of the pigment ar-
ranged in striate radial fragments about the lens of Hrythropsis as shown in
side view is remotely like his figure of the ocellus of Lizzia (1878, pl. 8, fig. 9)
in face view with radially arranged striate pigment masses encircling the lens.
It should also be noted that Hertwig (1884) compares the tentacle with the
stalk of Vorticella in that it is homogeneous, and has a fine cuticula.

In treating of Hertwig’s reply and reaffirmation that there are no cilia
upon Hryth ropsis, Vogt (1885b) merely condemns the certainty of the reaf-
firmation and compares it with the cautious statement regarding cilia not having
been observed, in the previously published account. He concludes that the

484 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

defense has but served to confirm his conviction that his exposure of Hertwig’s
error is sound, and that Erythropsis is only a Spastostyla which had been killed
in the act of eating the ocellus of a medusa.

Some months after Vogt’s exposure, Metchnikoff (1885) published a brief
note stating that he had seen an organism, which resembled that described by
Hertwig, in the living material taken in the tow net off Madeira, and had made
a brief reference to it in 1874 in a short note in Russian concerning his ‘‘ Reise
nach Madeira.’’ He suggested its affinities to the suctorian Ophryodendron.

Thereafter Erythropsis disappeared from zoological literature, as Vogt
(1885) had advised, for nearly a score of years. It does not appear in Biitschli’s
(1881-89) monograph of the Protozoa, or in any of the monographiec treatises
or text books written since Hertwig’s paper was published, with the single
exception noted below. Nor did Schutt, either in his monograph (1896) of
the Peridiniales or in his Plankton Expedition report (1895) make any mention
of Hertwig’s discovery. This is perhaps not strange since no one had as yet
suggested its affinities to the Dinoflagellata, and no investigator of this group
or subsequent observer had as yet seen any species of the new genus or verified
Hertwig’s discovery. Pouchet (1884, 1885a, b, 1886a, b, 1887) had in a series
of papers called attention to the ocellate Dinoflagellata but overlooked Hert-
wig’s related Hrythropsis. It was still under the cloud of suspicion raised by
Vogt’s criticisms, so that its true relationship was as yet unsuspected. The latter
is probably the case with Schitt’s omission, since he describes, as Pouchetia
cochlea and P. cornuta, two organisms which exhibit unmistakable resemblances
to Erythropsis. They both lacked ‘‘tentacles.’? However, this is a condition
frequently observed, in our experience, in other species of Erythropsis in which
the tentacle or prod is often dropped off prior to cytolysis.

The genus remained in this neglected condition until 1896, when Delage and
Hérouard in the course of their reorganization of the genera of the Protozoa
in their Traité de Zoologie Concrete brought this genus into relation with the
Dinoflagellata. They were still cautious, however, and admitted it only in an
appendix to this group, stating: ‘‘I] nous semble qu’il y a une autre manieére
de voir plus vraisemblable que les précédentes et que nous hasarderons tant
elle nous semble probable, mais sous toutes réserves et sans réconnaitre le danger
qu’il y a a formuler une opinion sur un étre que l’on n’a pu examiner.”’

Tt was not until 1904 that Pavillard (1905), himself an investigator of the
Dinoflagellata, found at Cette on the Mediterranean a single individual which
he recognized as an Erythropsis. He had a brief opportunity to sketch the
animal and concluded that it was Hertwig’s species rediscovered. He also for
the first time accorded it unquestioned place with the affiliated genera Pouchetia
and Gymnodinium; but, owing to the paucity of his material, he did not recog-
nize that his species was distinct from that of Hertwig, and that Schutt (1895)
had previously seen two other species of the genus, but, not recognizing
Erythropsis as a dinoflagellate, had placed these species in Pouchetia.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 48:

OU

The species was next discovered by Collin (1912), who recorded the dis-
covery of another individual in the student laboratory at Cette; also Fauré-
Fremiet (1914) stated that Chatton had seen one at Banyuls-sur Mer, in the
Mediterranean. Thus up to the time of Fauré-Fremiet’s discovery of his
‘‘vingtaine’’ of individuals at Croisic on the west coast of France only six indi-
viduals had ever been recorded, and observations on these had been restricted
because of the rapidity of cytolysis.

Unfortunately the misunderstandings which in the past had accumulated
about Hrythropsis were not dissipated by Fauré-Fremiet’s more abundant
material. He regards his species as identical with Hertwig’s H. agilis. It has,
however, a brown instead of a red pigment mass, albeit with a prominent red
core. Its proportions and structure, especially the ocellus, are so similar to
those of Hrythropsis figured by Pavillard (1905) from Cette that we regard it
as FH. pavillardi nom. sp. noy, and not HF. agilis Hertwig.

In three other very important particulars Fauré-Fremiet (1914) brought
confusion with regard to this slightly known organism. In the first place, he
oriented it with the epicone posterior and the prod anterior, thus reversing the
previous orientation. He also described and figured the transverse flage!lam
as arising in the distal end of the girdle from the attachment area, and running
around the body in the reverse of the direction universal in the Dinoflagellata.
Lastly he figures the longitudinal flagellum as emerging anteriorly from the
epicone. We have elsewhere (see Kofoid and Swezy, 1917) given the grounds
upon which these three conclusions should be rejected as wholly untenable.

SPECIES AND DISTRIBUTION

The first record of any form now referable to Erythropsis was made by the
eminent Russian biologist Metchnikoff, who published (1874) in his account
(in Russian) of his ‘‘Riese nach Madeira”’ a brief account of a delicate and
evanescent infusorian from the collections of the tow net in the tropical Atlantic
off Madeira in 1872, but did not figure or name it. He later (1885) recognized
its similarity to Hertwig’s Hrythropsis agilis, but believed its affinities to be
with the Suctoria.

This genus now includes ten species. The first of these is Hrythropsis agilis,
the type species originally described by Hertwig (1884) from the vernal plank-
ton of the Mediterranean off Sorrento. H. cochlea and E. cornuta were figured
by Schiitt (1895) as Pouchetia cochlea and P. cornuta from the collections of
the Plankton Expedition, presumably from the tropical Atlantic or from the
Bay of Naples. These, as figured, lack the prod, but the ocellus and epicone
are typically those of Erythropsis. In 1905 Pavillard deseribed and figured
a small species taken from the Mediterranean at Cette in October as EF. agilis
Hertwig. This was about half the size of Hertwig’s form with a girdle located
farther posteriorly, especially towards its distal end and with a black instead of
a red pigment body. In view of the speciation recorded by us in this genus
and the significance of size, girdle, and pigment mass in specific distinctions

486 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

therein, it seems imperative to conclude that Pavillard’s (1905) form is not
that of Hertwig (1884), but a distinct species which we call Erythropsis pavil-
lardi nom. sp. nov. In addition to these four species, LH. agilis, E. cochlea, E.
cornuta (Schitt), and HL. pavillardi, previously occurring in the literature, we
have brought to light six new species from the plankton of the Pacific off
La Jolla, California, to wit: Erythropsis extrudens sp. nov., E. richardi sp. nov.,
E. hispida sp. nov., FE. labrum sp. nov., E. minor sp. noy., and E. scarlatina
sp. nov.

It has not been possible, in the brief time and with the often scanty material
available for the inspection of the new species here described, to determine
all of the structural details essential for an adequate description. The loco-
motor activities and the ceaseless rapid contractions of the prod preclude con-
tinuous close observation while the normal structure persists, and cytolysis
abruptly terminates all possibility of further examination when activity ceases.
Discrepancies and inconsistencies with regard to such structures as the longi-
tudinal flagellum, the attachment area, and incomplete delineation of the com-
plicated contour and furrows of the epicone are attributable to these baffling
difficulties.

The prod or tentacle itself is subject to great modification in shape, position,
and completeness during the period of observation. All of our figures have
of necessity been made from individuals which have slowed down. In these
the prod is foreshortened by contraction, and perhaps in some cases has even
undergone autotomy. It was not infrequently entirely lacking in some indi-
viduals under observation, as it is in Schiitt’s (1895) figures of Pouchetia
cochlea and P. cornuta. While it is by no means certain that it is normally
present in both of these species of Schutt, the fact that we have found it present
in all species we have figured, including Hrythropsis cornuta (Schiitt), though
not in all individuals of these species which we have had under observation,
leads us to infer that it is a normal organ in the genus Hrythropsis, and will
ultimately be found in EF. cochlea Schiitt also. In view of these considerations
we have included Schitt’s (1895) Pouchetia cochlea in Erythropsis, although
no prod appears on his figures.

It is obvious from an inspection of the comparative figures (see text fig. SS)
of the known species in the genus Hrythropsis that they fall into two groups,
those with diffuse or compound lenses and lobed or radiate pigment masses,
referable to the subgenus Polyopsidella and the subgenus Erythropsis sensu
strictu, with condensed or simple undivided lens and compact pigment mass.
This first group exhibits the principle of repetition of parts and might be cited
as expressing multiple similar factors. Some degree of correlation between
lens and pigment spot appears in the fact that subdivision of the lens is in
every case accompanied by radiations (#. hispida) or lobing (FE. labrum) of
the pigment mass, though not by its complete subdivision. On the other hand,
the remaining seven species of the genus have an undivided lens and a compact
pigment mass without trace of lobes. ;

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 487

1. Subgenus Erythropsis (Hertwig)

Ocellus with single lens and undivided or non-lobed pigment mass, crowded
upon the left margin of the sulcus and protuberant anterolaterallv. Type
species EF. agilis Hertwig. Includes also EH. cochlea (Schutt), HE. cornuta
(Sehiitt), #. pavillardi nom. sp. nov., EL. extrudens sp. nov., and EH. minor
Sp. Nov.

2. Subgenus Polyopsidella subgen. nov.

Ocellus with several lenses superposed, in a linear series, or closely grouped,
pigment mass lobed, radiate or scattered. Type species, . scarlatina sp. nov.
Includes also EF. hispida sp. nov., E. labrum sp. nov., and EF. richardi sp. nov.

Kry To THE SPECIES OF Erythropsis

ee Ocellusmwathesineleysublennspherical seis sess ener tence ee 2

1. Ocellus with a compound lens of several distinct elements .........-.-2-2------c-c--ceceececeeeeeeceeeeeeeeeeees 3

PeaMentach excumecte da OsbevlOr liye wa. t.-<ccccse oeee<coe cen een teen ee oace nvcece acct ece dt sust ears Seances eevee cous cease 4

2. Tentacle directed obliquely ventral, capitate, with terminal stylet ........ extrudens sp. nov.

Al Veteeamaevants, ie @eellhyrsy Lopate ah TRG ec ener agilis Hertwig

Ame iomentwoteOce lis ail aC Kem Ors TC AN iva SO ese saceeceeee acess cree cars area see erence cee eee ee 5

5. Lens subhemispherical, pigment mass spheroidal, nearly twice diameter of lens, hypocone
SMD CIeCHareatrrele tera O Ut LN Cesena ere eae tae eens E ea cochlea (Schiitt)

5. Lens more nearly hemispherical, less than 1.5 diameter of the lens, hypocone elongated... 6

Gee Eipiconcewathedistinet, hormecumved towards thie) it sree e meee ee eee neeee eee ere nnsee nemene een 7

6. Epicone without horn, hypocone tapering, tentacle tapering, with stylet ..... minor sp. noy.

7. Tentacle slender, asymmetrically capitate, with stylet -............2......-..-. cornuta (Schiitt)

(eeRentaclemonecamd estou: wth OUSLY plOb eee acest ee nee ee eree re seene cee pavillardi nom. sp. nov.

3. Body pervaded anteriorly and ventrally with scarlet pigment, ocellus with a row of five
VETISES eeeeees mete tees ee ae OE ee IE ee eee scarlatina sp. nov.

SMSO Chivgas veil 110 UA SC UTE] Legg fON PIN TN eee eee ce cw eee een ec nae ce ee 8

8. Lens composed of numerous small rounded elements — Eee chee ie 9

8. Lens composed of two large, superposed elements —.......----.-------------- richardi sp. noy.

9. Lens composed of a line of five flattened ellipsoids, pigment brownish —__.. hispida sp. noy.

9. Lens composed of a cluster of about seven spheroids, pigment black —__.. labrum sp. noy.

Erythropsis agilis Hertwig
Text figures SS, 8, 12

(?) ‘‘Aeinetea,’’ Metchnikoff (1874), pp. 7-9.

Erythropsis agilis Hertwig (1884), pp. 204-212, pl. 6, figs. 1-10; (1885), pp. 108-112.

Spastostyla sertulariarum, Vogt (1885a), p. 53; (1885b), pp. 183-187, fig. 1.

Erythropsis agilis, Metchnikoff (1885), pp. 433-434.

E. agilis, Delage and Hérouard (1896), pp. 387-888, figs. 680, 681.

E. agilis, Pavillard (1905), pp. 48-49, pl. 3, fig. 1 (= E. pavillardi nom. sp. noy.).

E. hertwigi, Jollos (1910), p. 203. Lapsus for E. agilis Hertwig.

E. agilis, Poche (1913), p. 162.

E. agilis, Fauré-Fremiet (1914c), in part, pp. 27-47, text figs. 2 A-C. Pl. 1 and text figs.
1, 3-12 are ZH. pavillardt.

E. agilis, Kofoid and Swezy (1917), pp. 89-102, text figs. 9, 10.

488 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Dracnosis.—A large species with rotund body, truncate posteriorly; its
length 1.4 transdiameters; epicone flattened, small apical horn present; ocellus
simple, protuberant; lens spherical, with red flattened hemispherical pigment
mass: extended prod four times length of body. Length of body about 100+.
Mediterranean off Sorrento, April.

Description.—Hertwig’s (1884) figures and account of this species are the basis of this
description written from our present knowledge of the structure of the genus, which enables us
to interpret his data more completely. The body is rotund, wider posteriorly, its extreme length
in hfe, excluding prod, 1.4 transdiameters. The anterior part is flattened dorsoventrally and
expanded laterally, the widest part being slightly posterior to the equator. The dorsoventral
diameter is 0.99 of the transverse. The epicone is low and flattened anteriorly, its length is 0.2
of the total length. There appears to be a slight anterior horn, an elevation probably encircled
by an apical spiral which is evidently the anterior extension of the suleus upon the epicone.
In Hertwig’s figures (1884, pl. 6, figs. 3, 5) of this spiral it passes at the right side of the horn
and thence around to the left, not the reverse, as in our figures of this region in other species.
The hypocone forms at least 0.9 of the body, is almost circular in cross-section in the equatorial
region, flattened somewhat ventrally, truneated posteriorly and is cleft to the center by the deep
shthke tentacular recess.

The girdle is not clearly or consistently figured. It may begin anterior to the ocellus and
terminate near the problematical tentacle-like structure figured by Hertwig in the right mid-
ventral region. If so, its displacement is about 0.35 transdiameter, and the spiral crown on the
anterior margin of Hertwig’s figure must be in the rear, not the front of the body, and the
central spiral loop on the epicone of his figure must be the amoeboid upper end of the anterior
spiral of the suleus, and not any part of the girdle or transverse flagellum. There are sug-
gestions in the contours of Hertwig’s figures of paracingular lines and bands, but they are not
defined in either text or figures. The sulcus likewise is not indicated at all in his view of the
ventral surface sketched from memory of the living form. The tentacular recess is clearly
defined only in the one view (see his fig. 3) from the posterior end. It cleaves the body to the
center, but no indication of its anterior limits in the body in life or in the preserved individual
are available. The prod, as figured and described, is a cylindrical truneated structure twice
the length of the body when contracted and four times its length when expanded. Neither
granulations on the surface nor terminal stylet were noted, and no axial fiber, although Vogt
(1885b, fig. 1) reproduces Hertwig’s figure with such an axis to demonstrate its similarity to
the stalk of a vorticellid. Hertwig (1884) does, however, note the presence of folds on the prod
at disintegration, presumably the lines of constriction of the cireular fibers.

The ocellus is located opposite the region of the intercingular part of the suleus. It is of
the simple type with a spherical lens with concentric laminae and a flattened hemispherical,
red-pigment mass. Its total length is about 0.35 the total length or 0.45 transdiameter and its
axis is deflected to the left and ventrally about 5° from the major axis. The diameter of the ~
lens is a little over 0.25 transdiameter and it is sunk into the pigment mass for about one-third
of its diameter. It is made up of five concentric laminae, the outermost of which contains a
lens-shaped thickening on its axial, anteriorly directed region. The pigment mass is a reddish,
flattened hemisphere, 1.35 times the diameter of the lens in diameter on its posterior face, and
a low truneated cone anteriorly into which the lens fits. In the stained and mounted specimen
the pigment mass shows radial striations and cleaves along these lines. No central core was noted.

The nueleus is an ellipsoidal body, 0.6 transdiameter in length, flattened on the ventral face
(by shrinkage?) and located near the center of the body. It has a chromatin reticulum but
not moniliform threads. Numerous reddish-brown granules are scattered in the peripheral
plasma, especially posteriorly.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 489

A peculiar organ, designated by Hertwig (1884) as a ‘‘spoon’’ or spear, is figured at a point
corresponding to the right side of the sulcus, near its junction with the distal end of the girdle
and possibly the upper end of the tentacular recess. It is a reeurved ectoplasmic structure.
Its significance is problematical. It might be the contracted longitudinal flagellum, or the
denuded axial fiber of the tentacle or possibly an artifact. Its location militates against the
first two suggestions. Hertwig (1884) does not figure a longitudinal flagellum.

Divenstons.—These are computed on the basis of Hertwig’s (1885) state-
ment that the organism is 120 in length. Length, 120; transdiameter of body,
84; diameter of lens, 32; of pigment body, 45.

OccuRRENCE.—One individual seen by Professor Richard Hertwig in April,
1884, in the plankton of the Mediterranean off Sorrento, Italy.

Activities.—The tentacle was exceedingly active, contracting to half its
fully extended length, which was four times that of the body. The tentacle
was dropped off when the animal was placed under the cover glass.

SynonyMy.—This is the type species of the genus and of the new subgenus
Erythropsis sensu strictu. There is no critical evidence that the assignment
by Metchnikoff (1874) of the organism he discovered off the Madeira Islands
in 1872 to F. agilis is correct. In so far as his brief description goes, it might
equally well be applied to several other species in the genus. It will suffice to
regard it as an Hrythropsis and questionably FL. agilis Hertwig.

Pavillard’s (1905) assignment of a single individual discovered by him at
Cette to this species must be set aside and this individual assigned to a new
species, HL. pavillardi, on grounds given elsewhere in this paper. Jollos (1910)
inadvertently uses the name Hrythropsis hertwigit in referring to the organism
discovered by Hertwig. This name has no valid status.

It seems probable that the species described by Fauré-Fremiet (1914) as
E. agilis Hertwig is in reality FE. pavillardi nom. sp. nov. We have elsewhere
discussed (see Kofoid and Swezy, 1917) the grounds upon which we reject
Fauré-Fremiet’s proposed orientation of Erythropsis ‘‘agilis”’ with the tentacle
or prod anterior.

ComParisons.—This species is one of the specialized forms of the genus with
concentrated ocellus and large and powerful tentacle. Its ocellus resembles
that of FE. pavillardi and EF. minor, but it is much larger than either of these
species and has an entirely different tentacle, neither capitate nor tapering and
without stylet. Hertwig’s (1885) statement, if correct, that the length is 120y
makes EF. agilis next to the largest species in the genus. It is exceeded only by
E. cochlea.

Erythropsis cochlea (Schiitt)
Text figure SS, 7
Pouchetia cochlea Sehiitt (1895), pp. 96, 169, pl. 26, fig. 95.

DiaGnosis.—A very large species with rotund body, its length 1.2 transdiam-
eters; girdle displacement (?); ocellus not protuberant, with small spheroidal
lens, and a large black spheroidal pigment mass; prod not noted; peripheral
vacuoles subpolygonal, crowded. Length, 130. Atlantic (?) or Bay of Naples.

490 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

DEScRIPTION—Owing to the fact that Schiitt (1895) gives only a single figure, of the dorsal
side, with very incomplete delineation of girdle and little of the suleus, our description is limited.
However, an analysis of this figure in the light of the fuller knowledge of the genus is desirable
for the orientation of the species.

The body is very rotund, its length 1.2 transdiameters. Epicone 0.25 of the total length,
culminating at the left in a blunt apical point, sloping to the right about 20° and ventrally.
The hypocone has almost a circular outline to the level of the girdle, above which the epicone is
abruptly reduced, especially at the right, to 0.6 the greatest diameter, which is 0.4 of the total
length from the antapex. The right side is more rotund than the left and the antapex is
hemispherical.

The girdle is not differentiated in form in Schiitt’s figure from the precingular and post-
cingular grooves. Assuming that the apical point is encircled by the upper end of the sulcus,
it appears that Schiitt has represented below this trough of the sulcus the precingular groove
and the girdle below it. It forms a descending left spiral of considerable displacement. The
furrow, as figured, is no more than a narrow groove. The sulcus is entirely without repre-
sentation, except for the uppermost part, as above interpreted. No indication of tentacular
recess or of the prod is given. The precingular groove is well defined, parallel to the girdle and
separated from it at all points on the dorsal side by a distance of 0.11 transdiameter. The
surface between the girdle and the precingular groove is convex.

The ocellus is composed of a spheroidal leris of concentric layers, 0.16 transdiameter in
diameter, imbedded in the anterior face of a spherical pigment mass 0.23 transdiameter in
diameter. It is black peripherally with a reddish-brown core. These are like scattered pigment
granules or processes.

The nucleus (?), as figured by Schiitt, is extraordinarily large. It is ellipsoidal in form
with its major axis 0.72 and its minor axis 0.48 transdiameter in length. It lies obliquely across
the right side of the hypocone. The surface of the body is closely set with compressed sub-
polygonal uniform vacuoles, about forty across the dorsal side at the equator. In optical section
a radially arranged group -of structures of about twice the size of the superficial vacuoles is
figured in the peripheral cytoplasm of the hypocone. They do not appear to be rhabdosomes,
nor are they in size and distribution the equivalents of the superficial vacuoles above noted.

Diwenstons.—Length, 130; transdiameter, 110+; diameter of lens, 17; of
pigment mass, 27+; of nucleus, 75.

OccuRRENCE.—Figured by Schiitt (1895) from the Bay of Naples or the
Atlantic. We have not found it at San Diego.

ComParisons.—Schiitt’s figure suggests an Erythropsis in a moribund con-
dition, as indicated by the rounded form, the contracted state of the transverse
furrow, and by the vacuolated periphery. The absence of the extended prod
is confirmatory evidence of this supposition. The ellipsoidal structure in the
hypocone which we have tentatively interpreted as the nucleus may be a food
body. The fact that the nucleus is extraordinarily transparent in Hrythropsis,
and usually lies far anterior, while in Schiitt’s figure this ellipsoidal structure
is far posterior, gives rise to this alternative interpretation. This is the largest
species known in the genus, the most rotund (as figured) and has the concen-
trated form of ocellus resembling that of E. cornuta, E. minor, and EF, extrudens.

The structure of the epicone with its anterior horn or apical point with
encircling anterior loop of the sulcus and its precingular groove are entirely
typical of Erythropsis, and not of Pouchetia, and the ocellus is of the simple

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 491

type found in one group of species in Hrythropsis, but not in Pouchetia. For
this reason we include this species in Erythropsis. It is a highly specialized
form, as well as the largest.

Erythropsis cornuta (Schiitt)
Plate 12, figure 129; text figures RR, 1; SS, 1; UU

Pouchetia cornuta Schiitt (1895), pl. 26, figs. 96,_,.

P. cornuta, Lemmermann (1899), p. 360.

P. cornuta, Lang (1901), p. 161, fig. 75 A.

P. ccrnuta, Payillard (1905), p. 48, as synonym of Erythropsis agilis Hertwig.

Draenosis.—A large species with ovoidal body; length 1.25 transdiameters,
with distinct curved apical horn; girdle displaced 0.65 transdiameter; ocellus
protuberant; lens simple, hemispherical; pigment mass subhemispherieal, with
red core; prod capitate, with terminal stylet, axially located. Length, 104.
Atlantic, Pacific, off La Jolla, California, July, August.

Description.—The body is ovoidal, widest anteriorly, its length 1.25 transdiameters, dorso-
ventral and transdiameters equal. The epicone is small, its diameter in ventral view less than
0.5 transdiameter, apex broadly rounded with a short but very clearly differentiated hook-
shaped apical horn about two widths of the girdle in height and curved to the left. Ventrally
the height of the epicone is only 0.25 transdiameter, except in the slender, posterior projection
along the distal end of the girdle which reaches a little beyond the middle of the body. The
epicone contains less than 0.15 of the total volume of the body. The hypocone has a length
midyentrally of 0.75 of the total length of the body and much more dorsally. Its anterior
region is contracted to about 0.5 transdiameter to meet the small epicone. Its right side is more
convex, its left somewhat flattened below the ocellus, and the body contracts gradually posteriorly
to 0.4 transdiameter at its somewhat truncate antapex.

The girdle originates at the anterior flagellar pore above the ocellus, forms a flat spiral
slightly below the anterior margin on the left and dorsal sides, and in the distal quadrant turns
posteriorly at an angle of about 30° from the horizontal, increasing to 70° in its most distal
region to its junction with the suleus. The total displacement in the intercingular region is
0.65 transdiameter. The transverse flagellum reaches about 0.5 of the cireumference. The
furrow is sharply but not deeply impressed and is bordered by parallel paradinial lines. The
anterior paracingular band is wider than the posterior, the former slightly exceeding, the latter
slightly less than the width of the furrow. These lines are clearly defined in this species. At
the distal end of the furrow on its anterior margin is a deep pit, the attachment area, the point
at which presumably the anterior horn of the posterior schizont remained jointed to the anterior
sister cell at binary fission. The suleus is a very narrow groove running from the anterior
flagellar pore obliquely posteriorly on the right side of the ocellus, curving again below it to the
left and continuing beyond the middle of the body to its junction with the tentacular recess.
This cavity is broadly and asymmetrically campanulate, with a dorsal ledge, a deep pit around
the shaft of the prod and a wide right flap which projects over the midventral region. The
depth of the recess is 0.3 of the total length of the body. No longitudinal flagellum was seen,
but the posterior pusule may mark the point of its origin.

The prod is elongate cylindrical, reaching, when extended, a total length 2.3 that of the
body, and when fully contracted retreating wholly within the postmargin of the tentacular
recess. It is distinetly capitate distally, with a knob twice the diameter of the shaft at the

492 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

maximum of contraction and about 1.5 diameters when extended. Long before cytolysis sets
in the size of this knob was reduced by a distal sloughing off of its substance which first became
limpid clear and then detached itself with adjacent granular plasma. Both before and after
this sloughing it was distally somewhat asymmetrical. There is a small articular, distal stylet
whose length does not exceed the diameter of the shaft and a central axial retractor fibril, but
no marked evidence of circular protractors.

The ocellus is relatively small. Its length is 0.42 transdiameter and its major axis is deflected
about 25° to the left and ventrally from the axis of the body. It projects from the body almost
the full length of the lens. The lens is hemispherical, consists of regular, equidistant, concentric
laminae and is buried slightly in the black melanosome of the pigment mass. This is sub-
hemispherical, being enlarged on its lower outer region. It contains a coral-red core.

Fig. TT. Erythropsis extrudens sp. nov. 1. View of the right side with tentacle fully extended. 2. Left
side, tentacle retracted. 3. Anteroventral view of moribund individual showing granular stump of amputated
tentacle and structure of epicone with girdle and paradinial lines. 4. Ocellus shortly before cytolysis, showing
modifications of concentric lines in the lens. 5. Ocellus shortly after cytolysis of cell body, showing zone of
solution about the distended lens. 6. Rounding up of detached lens, red core still in melanosome. 7. Last
stages of solution of melanosome and core. 8. Persistent transverse flagellum after cytolysis. X 333.

The nucleus is ellipsoidal, with major and minor axes of 0.57 and 0.40. transdiameters
respectively. It hes obliquely in the right anterior part of the body. The chromatin network
was not visible. The anterior pusule arises at the anterior flagellar pore, passes posteriorly
obliquely across the level of the girdle, where it expands somewhat and is continued obliquely
posteriorly to an opening at the right side of the tentacular chamber, at a point which may
correspond to the posterior flagellar pore. The two pusules are thus in this individual con-
nected in a continuous canal. Several refractive oil granules he in the plasma adjacent to the
suleus, and a small food remnant lies near the nucleus. Peripheral vacuoles of cireular to linear
form and minute size filled with a bluish-green fluid lie in the peripheral plasma. The general
color tone of the plasma is a pearl grey.

Divenstons.—Total length, 104; of extended tentacle, 240; of ocellus, 33+;
transdiameter, 814; diameters of nucleus, 42/ and 34+.

OccURRENCE.—Three individuals taken in collections made with a net of
No. 25 silk from a depth of 80 meters, 6, 4, and 0.75 miles off La Jolla, California,

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 493

July 23 and 27 and August 20, 1917, in surface temperatures of about 20°2 C,
oer oe and 22 1 ©,

Schiitt (1895) figures it, presumably from the Bay of Naples or from the
Atlantic.

Activities.—The individual under observation was brought to the labora-
tory at 10 a.m. and was first captured in the large jar of fresh sea water at
4 p.m. and placed under the cover glass. It remained active for only a few
moments, keeping the prod in rapid, regular contractions several times per
second and moving spasmodically in an anticlockwise circle of short radius.
The prod soon began to slough off, its contractions to become irregular, and the
outward thrust to grow shorter and shorter, until within an hour all movement
ceased and cytolysis ensued.

SynonyMy.—Figured as Pouchetia cornuta by Schiitt (1896, pl. 26, figs.
96,-;), who failed to recognize its relationship to Hertwig’s Hrythropsis. The
fact that he does not list Hertwig’s (1884) paper in his bibliography or recog-
nize the genus in his Pflanzenfamilien (1896) indicates that he did not recognize
Erythropsis as a dinoflagellate. His figure and text alike show that he did
not recognize the tentacle or prod. His drawing was evidently made from a
moribund specimen. ;

CoMPARIsoNs.—Our individual appears to be identical with the form figured
by Schiitt (1895, pl. 26, fig. 96) as Pouchetia cornuta. His magnification gives
a length of 105« for his smaller figure and 120 for the larger, at the same
magnification. However, the magnification is not given for the larger figure,
though both are said to have been made from the same living cell. The tentacle
is probably represented by the rounded knob from whose base the longitudinal
flagellum springs. The outline, girdle, sulcus, and paracingular lines are strik-
ingly similar in his figures and ours, although he did not record the intercing-
ular part of the sulcus, and undoubtedly portrays incorrectly the proximal end
of the girdle as ascending to the tip of the apical horn. This horn is also figured
as deflected to the right, whereas we record it as deflected to the left. This may
be due to its mobility or to inaccuracy of record on the part of one of us. In
view of the difficulties in securing an accurate interpretation of this obscure
region, these discrepancies may be regarded as negligible, in so far as they
affect the question of specific identity.

This species is close to H. agilis Hertwig, but differs in shape of the body
and lack of broadly truncate antapex. The ocellus is of the same simple
type, but the melanosome is extended longitudinally instead of transversely,
as in FE. agilis, and the apical horn is more fully developed. The body is
smaller and far less rotund than in #. cochlea (Schutt) and larger and stouter
than in EL. pavillardi, and its prod is of a different type, having a terminal stylet.
The posterior position of the prod differentiates it from H. extrudens, and its
very large size and long prod, as well as its much deflected, distal end of the
girdle, separate it from EF. minor.

494 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Erythropsis extrudens sp. nov.
Plate 12, figure 130; text figures SS, 11; TT

DraGnosis.—A large species with rotund body, flattened anteriorly, slightly
laterally compressed posteriorly; epicone at left forming 0.2 total length;
hypocone deeply furrowed ventrally by tentacular recess; girdle displaced pos-
teriorly about 0.5 total length; stout oblique contractile prod or tentacle with
capitate-pointed end, terminating in a stylet; ocellus slightly protuberant with
concentric hemispheroidal lens, black pigment, and red core. Length, 89+.
Pacific, off La Jolla, California, July.

DescripTion.—The body is rotund, collapsed posteriorly in individuals which have dropped
off their tentacle, spheroidal in active forms with tentacle intact. The anterior end is much
flattened and the posterior notched by the deep suleus and tentacular recess. In collapsed
individuals the posterior end is laterally compressed to about 0.5 transdiameter anteriorly.

The body is so diversified by the girdle and its attendant paracingular grooves, the pro-
truding eyespot, the deep sulcus, and the basal mass of the tentacle that the unraveling of its
complicated structure is a matter of serious difficulty, especially since the animal while intact
is incessantly on the jump, so that complete camera outlines are impossible and the views
presented change with every move of the animal. The analysis here given is the result of the
prolonged study of three different individuals, only the first of which possessed this tentacle,
the mutilated base alone remaining on the other two.

The greatest difficulty attends the analysis of the girdle and sulcus, because of their routes on
the flattened apex and across the black pigment mass, and because of the paracingular grooves
which confuse the observer. The analysis made on the three individuals is sufficiently coherent
to lend support to the hope that it is the correct one, but the difficulties are so baffling that
certainty has not been attained.

The girdle is of the Gyrodinium type, that is, displaced at its distal end posteriorly for a
considerable distance, about 0.5 of the total length of the body. The flagellar pore of the
transverse flagellum lies in a depression just anterior to the ocellus. F'rom this point the girdle
sweeps dorsally around the flattened epicone under a widely overhanging upper lip and descends
rapidly as a relatively shallow furrow, obliquely posteriorly across the right face, terminating
at a posteriorly directed notch on the edge of the deeply infolded, ventral suleus. The very
active transverse flagellum traverses the proximal 0.6 of this girdle.

The suleus invades the epicone for a short distance above the anterior flagellar pore, skirts
the right side of the ocellus, sinks deep into the tentacular recess which is continued posteriorly
across the antapex. No longitudinal flagellum could be found. Its point of origin, or the
posterior flagellar pore, may be located at the opening of the posterior pusule. The notch at
the distal end of the girdle was not detected on the individual with the tentacle while it was
active. This is probably the attachment area.

The epicone thus has a length on the left side of the sulcus of about 0.2 and on the right side
of about 0.66 of the total length of the body, but owing to the rapid descent of the girdle in its
distalmost part the epicone as a whole forms but a small part (less than 0.1) of the total body.

The girdle is attended, in fact paralleled throughout most of its course, by certain surface
depressions, or paracingular grooves or lines (fig- RR, post. and pre. par. 1.) strongly suggestive
at first sight of the shghtly impressed, spirally twisted suleus of Pouwchetia and Cochlodinium.
Repeated efforts to bring these shallow markings into agreement with such an interpretation
and to give to the furrows the organization of Pouwchetia which the presence of the eyespot leads
one to expect were fruitless. Semiapical views of collapsed and therefore quiet individuals

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 495

finally gave the clue to the interpretation here presented. Paralleling the furrow of the trans-
verse flagellum throughout most, if not the whole, of its course, both anterior and posterior to it,
are shallow depressions—the paracingular grooves. The anterior, or precingular, groove is the
more plainly visible, more deeply impressed, and is separated by a somewhat wider interval
from the furrow than the postcingular groove, except where the latter skirts the right side of
the sulcus.

The most remarkable feature in the structure of this bizarre animal is its ventral tentacle
or prod, a mobile and rhythmically contractile structure, located towards the posterior end of
the body in the midventral plane in the tentacular recess of the expanded suleus. It is an
elongated structure, consisting of a base, shaft, head, and stylet, extending ventroposteriorly in
the median plane. It is held habitually in this plane at an angle of 10°—25° below the horizontal.
It is, however, capable of a considerable latitude of movement (fig. TT, 1, 2) and exhibits much
flexibility in action. It rises from a low, spreading, convex, granular base, which is 2.5 times
the thickness of its shaft in diameter, and extends for 0.5 its length in a rounded mass into the
elsewhere hyaline substance of the body. The exposed conical portion forms an asymmetrical
cone of about 40°, which forms about 0.33 of the length of the partially extended tentacle, or
almost wholly, disappears in the fully extended one (pl. 12, fig. 130). When the prod is fully
contracted this base swells up into a rounded dome which now includes most of the substance
of the cylindrical shaft. This shaft is the connecting link between the head and the base and
emerges at the expense of the substance of the latter. When fully extended it is cylindrical
throughout, about.0.6 the diameter of the head in diameter and 0.8 of the length of the body in
length. The head is subsymmetrieally biconical, 0.15 of the length of the body in diameter, and
its proximal and distal conical surfaces subtend angles of about 60° and 70° respectively.
Distally it passes abruptly into a rodlike stylet, 1.25 its diameter in length. This is a cylindrical
hyaline rod, not a mobile flagellum, although it has some elasticity, bending when in contact
with the substrate, but having no independent motion of its own.

From the right side of the base of this prod there passes distally on its surface in a partially
spiral course a shallow, granular line, possibly a groove. This terminates on the outer face of
the head. The only plausible explanation of this is that it is the morphological extension of the
sulcus. Owing to the folded contour of the suleus at the base of the tentacle, nothing more
than the union of this groove at its proximal end with the suleus could be detected. It is to be
noted that this point of juncture is immediately adjacent to the notch of the distal end of the
girdle and not far from the possible location of the flagellar pore.

The internal structure of this remarkable organ consists merely of a light area, a vacuole in
the head, and two sets of antagonistic striations, outer circular and inner longitudinal, marked
by lighter lines and attendant granulations in the case of the circular fibers. Their behavior
in the contracted and extended condition of the tentacle indicates their function as protractor
and retractor muscles.

The second outstanding feature of this species is the eyespot or ocellus. It consists of three
parts, the lens, melanophore or melanosome, and core, the latter two constituting the pigment
mass. It is located far anteriorly, immediately posterior to the proximal end of the girdle in
the projecting lobe formed by the anterior angle of the hypocone to the left of the intercingular
suleus. It lies beneath a rounded eminence more evident in an obliquely lateral view of the
right side of the body. The lens is directed anteroventrally and is elongate hemispherical in
form with its base buried in the pigment mass. It consists of three concentric masses of hyaline
material, the middle one of which is internally trilobed, and the outermost shows minor con-
centric lines. It is not externally lobed or divided. On eytolysis it elongates and shows a semi-
segmented form with a clear membrane and then rounds up in a spheroidal lump (text fig.
TT, 47).

496 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The pigment mass consists of a black melanosome surrounding and almost hiding a bright
red central core and changes outline with the varying positions of the body and with the
approach of cytolysis. It varies from flattened to elongate hemispherical form with varying
irregularities on its surface, but had no amoeboid, dendritic or reticulate processes when observed.
Several detached globules of the pigment lie on either side of the girdle just below the ocellus.

Fig. UU. Erythropsis cornuta (Schiitt). 1. Ventral view with prod fully expanded. 2-4. Stages in
sloughing off end of prod. 5. Dorsal view with tentacle partly retracted. Blob below cast off plasma from
prod. X 500.

There is a large sacklike, clear, pinkish pusule extending posteriorly from the anterior
flagellar pore on the dextrodorsal side of the ocellus and another smaller pink sack with lobed.

diverticula, posterior to the ocellus and adjacent to the distal end of the girdle. The connection * —

of this with the pore by a canal was not noted. The anterior sack was far less pink in color
than is usual with the contents of pusules. It seems probable, but not certain, that these two
structures are pusules attached respectively to the anterior and. posterior flagellar pores.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 497

The nucleus is a very clear, broadly ellipsoidal body in the anterodorsal region, with major
and minor axes of 0.5 and 0.4 transdiameter respectively. It has an outer clear zone enclosed
within the outer nuclear membrane. No chromatin strands could be detected in its substance.
The cytoplasm of the body as a whole was throughout of a glassy, glaucous, hyaline appearance
with remarkably few alveoli or granules of appreciable size.

The surface of the body is devoid of striae or other markings except for the lines and zones
paralleling the girdle. However, as the animal grows less active, peripheral vacuoles arrange
themselves in the subsurface zone in a somewhat linear fashion, with their longer axes longi-
tudinal and their lines longitudinally disposed, indicating at least an internal linear organization
of the peripheral layer of cytoplasm.

Dovenstons.—Length of body, 90-117; of extended tentacle, including
stylet, 60-70; of stvlet, 17+; diameters, transverse 70-85, dorsoventral 73.

ACTIVITIES.—Only one normally active individual has been under observation.
This was swimming rapidly in anticlockwise spirals of a radius not exceeding
several lengths of the body, without rotation except for an occasional somer-
sault. During this period, and subsequently when the circus motions slowed
down, the prod was incessantly repeating its rhythmical contractions with brief
intermissions.

After about thirty minutes under the cover glass the contractions slackened
in vigor and slowed down from the earlier rate of 80 per minute, became less
regular, and of smaller amplitude, and finally ceased. Shortly after this the
contracted prod was detached at its base by local cytolysis and speedily disin-
tegrated, with only a few circular and longitudinal fibers remaining intact for
a brief time.

The behavior of this strange organ was observed for about two hours before
it was cast off and underwent immediate cytolysis. When first observed the
animal was very active, swimming about in anticlockwise spirals. When the
spiral circling ceased temporarily the tentacle still kept up a continuous,
rhythmical, alternating retraction and protraction without cessation or modifi-
cation, except as interfered with by the substrate or other obstacles, or by the
locomotor activities of the animal. When first timed, at a stage of somewhat
slackened activity, these recurrent thrusts of the prod were carried on at the
rate of one every 0.75 second. The regularity of the action was remarkable
and the continuity of it equally impressive and no less exasperating when one
was attempting to get a sketch, to say nothing of a camera outline, of this
extraordinary animal.

The action was continued whether in contact with the substrate or not. In
case the extending tentacle met the resistance of another body this was vigor-
ously thrust away if it was a small one. If, on the other hand, it was larger, as
in the case of the carapace of a copepod, the body of the Erythropsis was itself
pushed away at once by the vigorous thrust of the prod. The terminal stylet
exhibits considerable rigidity under such impacts. The result when the prod
met the substrate was equally effective. When lying obliquely on its side the
tip of the prod was in contact with the glass and this contact was sufficient

498 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

continuously to thrust the body backward for a distance equal to 0.25 to 0.50 its
diameter with each thrust of the prod.

Cytolysis of the body ensued about an hour after autotomy and disappear-
ance of the prod. The approach of this catastrophe is first indicated by the
rapid formation of minute liquid spherules extruded simultaneously on all
sides of the body, apparently by the discharge of the fluid accumulating in
the peripheral vacuoles. This is speedily followed by the rupture of the
peripheral pellicle, the outpouring of the contents of the body and its rapid
and complete liquefaction. The reversal of the living substance from a gel to
a sol is complete and takes place with remarkable rapidity, the pellicle disap-
pearing as rapidly as the cell contents (text fig. TT, 8). In the last vestiges
of the granular cytoplasm the short transverse flagellum was observed with
active undulating contractions still passing through it. The organs which resist
solution longest are the nucleus and the ocellus. The nucleus gradually wastes
away, the peripheral clear zone and chromatin network becoming more distinct
before final disruption and solution. It appears to be a more resistant gel than
the surrounding cytoplasm.

The cytolysis of the ocellus (figs. TT, 4-7) when released by solution of the
surrounding cytoplasm proceeds slowly to a complete disappearance in about
twenty minutes. The lens elongates, becomes surrounded by a clear zone, pre-
sumably a sol, formed from its own substance, is released from the pigment
mass in which it is embedded and rounds up into a sphere which gradually
wastes away as the zone of solution about it becomes indistinct. The brilliant
red, central core flows out from the center of the melanosome (figs. TT, 4-7)
and rounds up in several spherules. The melanosome also rounds up and the
two colored masses very gradually waste away without imparting any recog-
nizable tint to the surrounding water.

OcCCURRENCE.—T wo specimens of this species were taken July 12, 1917, with
a No. 25 net, ina haul 6 miles off La Jolla, California, in a haul from 80 meters
to the surface and in a surface temperature of 20° C. The same day another
individual was noted in a haul made on the previous day and kept in the labor-
atorv over night. This was made at a distance of 4 miles off La Jolla, from 80
meters to the surface and in a surface temperature of 19°8 C.

ComParIsons.—E. eartrudens is the most highly specialized and widely
divergent member of the subgenus Erythropsis, and is nearest of all its members
to the subgenus Polyopsidella. The structural features indicating this are the
detached pigment particles, the marked internal stratification of the lens sug-
gesting a transition to or from the compound condition, the reduction in the
size of the tentacular recess, and the oblique tentacle or prod. These features
are not unlike the divided lens of F. hispida, the scattered pigment of £. labrum,
and the reduced recess and oblique prod of E. scarlatina, all included in Poly-
opsidella. Since, however, its lens is not externally divided into separate lobes,
E. extrudens is not placed in the subgenus with compound ocellus, but it is

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 499

evidently a transition form close to it. The ventral position of the prod is more
marked than in any other species, and its differentiation into shaft, head, and
stvlet most complete, while the spiral tract on its surface was not detected in
any other species.

Erythropsis hispida sp. noy.
Plate 12, figure 127; text figure SS, 2

DraGcnosis.—Medium sized species with ovoidal body, its length 1.46 trans-
diameter ; girdle displaced 0.6 transdiameter ; ocellus not protuberant, lens com-
posed of a row of six spheroids at the left of the sulcus, pigment mass spheroidal,
dark brown with brownish radiations; prod slender, not capitate, hispid, with
short terminal stylet; peripheral vacuoles elongated, crowded, orange pink.
Length, 894. Pacific off La Jolla, California, August.

Description.—The body is ovoidal, its length 1.46 transdiameters, measured at the widest
part, which is slightly above the equator. The dorsoventral diameter slightly exceeds the trans-
verse. The epicone is much smaller than the hypocone and is shifted towards the right by the
displacement of the girdle, which is about 0.6 transdiameter. The height of the epicone at the
proximal end of the girdle is 0.12 of the total length of the body and 0.5 at its distal end. The
apical region is highest at the left, slopes rapidly to the right and is less flattened than usual.
No anterior horn was noted. The hypocone forms more than 0.75 of the body, is distended in
an equatorial region on the sinistral face and is slightly flattened at the antapex, especially in
lateral view.

The girdle forms a steep, descending left spiral, displaced distally 0.6 transdiameter. It is
steepest in its distal region on the ventral face. Its two ends reach the median plane. The
transverse furrow is very narrow, 0.04 transdiameter in width, and deeply impressed. The
precingular groove runs subparallel to the girdle throughout its course, diverging anteriorly
from it as it proceeds distally, from one width of the furrow at. the proximal end to four widths
at the distal end. The distal end of the groove turns abruptly anteriorly and appears to die
out alongside the sulcus. The surface between this groove and the transverse furrow is broadly
concave. No postcingular groove was noted. The suleus begins at the summit of the epicone
to the left of the main axis, curves to the right, joins the girdle, curves in a slight convexity to
the right of the ocellus, joims the distal end of the girdle and merges in the deep, terminal, axial,
tentacular recess. This cavity is 0.27 of the total length of the body in length and about 0.2
of the greatest diameter in width when it expands about the base of the tentacle. It contracts
slightly midway of its length and flares distally into the posterior opening about 0.25 trans-
diameter across. The left flap of the sulcus folds slightly over the right, hiding the upper part
of this tentacular recess.

The transverse flagellum does not completely encircle the body. No longitudinal flagellum
was noted and an attachment area on the anterior lip of the distal end of the girdle was not
detected.

The prod was not observed in full activity. As noted in the single individual of this species
which we have seen it was a slender, almost cylindrical structure, located in the axis and directed
posteriorly. Its total length, including the short stylet, was almost equal to the transdiameter
and its diameter about 0.08 of the same. It has a globular enlargement at its base whose
diameter is 1.5 that of the shaft. It enlarges slightly towards its distal end, but is only slightly
capitate even when contracted. At the distal end it bears a short, acute stylet whose length
does not exceed the diameter of the prod. Its axis contains a slender axial thread, the retractor

rc

500 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

muscle, and the distribution of the fine points on its surface suggests the possession of circular
contractile fibers, the protractor muscles. Its surface is everywhere covered, except at the tip,
with minute pointed elevations, giving to it a characteristic hispid appearance, hence the specific
name hispida. Upon the stimulus of contact the tentacle was contracted, growing stouter and
more capitate as a result.

The ocellus is of the compound type, and is unique among the varied ocelli of this genus in
that it consists of a row of lenses applied to one face of the pigmented sphere, with radial
streamers. The lenses lie on the left side of the intercingular part of the suleus immediately
against its margin. Viewed from the left, as in our figure (pl. 12, fig. 127), they appear as
flattened spheres whose diameter is slightly greater than that of the tentacle. When viewed
more from the right it appears that their diameter in the transverse direction is nearly twice that
in the vertical, that is, they are flattened ellipsoids. There are six of these lenses, subequal with
the terminal ones, somewhat smaller, and all subject to irregularities in contour.

The pigment body is spheroidal, flattened on its right face where the lenses lie in contact
with it. Its diameter is about 0.3 transdiameter of the body. At equidistant points on its
circumference it sends off into the surrounding cytoplasm feathery tapering streamers of its
substance, the longest of which are about equal to its radius in length. Its color is a brownish
black with brownish core and streamers shading into brick red. It is noteworthy that the axis
of the ocellus as a whole is here less definitely directed anteriorly than in the simple type of
ocellus.

The periphery of the body after prolonged confinement under the cover glass presents a
characteristically mottled appearance due to a reticulum of pale glaucous green cytoplasm con-
taining in its meshes a salmon-pink fluid, tinged with aniline yellow, with a resulting pale cream
tone to the body as a whole which has the usual glassy translucent texture prevalent in all the
species of Erythropsis. A small pusule is connected with the tentacular recess with an accessory
spheroidal one close at hand. Another similar sphere lies near the anterior flagellar pore, but
no pusule connecting either with the pore or sphere was noted.

The nucleus is broadly ellipsoidal, with the major axis 1.25 the minor, and subparallel to the
major axis of the body. It hes slightly anterior to the middle of the body. No moniliform
chromatin threads were evident. No chromatophores or food balls were present.

Dimensions.—Length of body, 894; transdiameter, 614; major axis of
nucleus, 30; length of tentacle, probably contracted, 554; diameter of pigment
body, 20; of lenses, 6" by 10+.

OccURRENCE.— Ohne individual taken in a haul of a No. 25 silk net 0.75 mile
off La Jolla, California, August 13, 1917, from 83 meters to the surface in
surface temperature of about 22° C. It occurred with #. minor and another
undetermined species of Hrythropsis.

Comparisons.—This species belongs to the subgenus Polyopsidella with
compound lenses including Erythropsis scarlatina, E. labrum, and E. richardi.
It is nearest in this particular to the first named, having six instead of five
lenses in the row. It is unique in the radial processes from the pigment body
and has the most asymmetrical epicone in the genus. The mottling of the
surface is somewhat like that figured by Schutt (1895) for Pouchetia (= Ery-
thropsis) cochlea. The tentacle is of the non-capitate form seen in EL. scarlatina,
E. minor, and E. richardi, but bears a terminal stylet as in F. cornuta, FE. minor,
and EH. extrudens, and is posteriorly directed as in all species except EH. extru-
dens. 'The species is unique in the genus in the pattern exhibited by the

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 501

peripheral vacuoles which are close set as in EL. cochlea (Schutt), but through-
out the surface the individual vacuoles exhibit an anteroposterior elongation
wholly lacking in FE. cochlea, The salmon-pink color is also unique.

Erythropsis labrum sp. nov.
Plate 12, figure 132; text figure SS, 6

DraGnosis.— Large sized species with ellipsoidal body, its length 1.55 trans-
diameters; girdle displaced 0.2 transdiameter; sulcus with overlapping, anter-
iorly directed flap on right side; ocellus deeply imbedded; lens composed of
seven spheroids; pigment mass deeply and irregularly lobed, black, with yellow-
ochre core and widely scattered granules; prod capitate, without stylet ; periph-
eral vacuoles elongated longitudinally, scattered irregularly. Length, 111.
Pacifie off La Jolla, California, August.

DescripTion.—The body is broadly and not quite symmetrically ellipsoidal, its length 1.33
transdiameters measured at the widest part which is at the middle. The dorsoventral diameter
is a trifle less than the transverse. The right side is evenly convex and the left and dorsal are
somewhat flattened. The left side of the body extends somewhat farther posteriorly, as in the
ease of the left horn in Ceratium. The epicone is much flattened, forming a low cone whose
base has a diameter of 0.7 transdiameter and an altitude at the proximal end of the girdle of
0.18 of the total length of the body and of 0.33 at the distal end on the right ventral side.
Dorsally its lower margin scarcely lies below the summit so that its surface slopes mainly to
the right and ventrally and constitutes as a whole less than 0.1 of the total surface. It has no
distinct apical horn, although there is a slight hump at the right of the tip of the suleus. The
hypocone forms over 0.9 of the body, is slightly contracted posteriorly, and has a broadly rounded
antapex, slightly cleft by a broad groove from the tentacular recess, with the lobe on the left
about two widths of the furrow longer than that on the right.

The girdle ascends steeply from the anterior flagellar pore to almost the anterior margin
along the dorsal side, then turns posteriorly with a reversed curve on the ventral face, so that
the total intercingular displacement is about 0.22 transdiameter. It makes a complete turn
around the body, but its junction with the suleus is hidden by the anterior lobe of the flap of
the right side of the suleus. The furrow is rather deeply impressed and is about 0.03 trans-
diameter in width. It is paralleled by paracingular lines or precingular and postcingular grooves
equidistant from the furrow, each about a width of the furrow removed from its margins.

The sulcus extends from apex to antapex, fading out anteriorly in a feebly marked loop at
the left of an apical hummock, the homologue of the horn of #. cornuta. It makes a flat, reversed
curve as it joins the girdle at the anterior flagellar pore, passes to the right of the-lenses, joins
the distal end of the girdle beneath the anterior flap, and then widens out into the deep, axially
located, tentacular recess. This recess and the intercingular section of the suleus are hidden
beneath the widely overlapping, right flap (hence the specific name labrum) which extends anter-
iorly as a free lobe from the distal end of the girdle, so far as to cover over the anterior flagellar
pore. This flap is notched at the tip, which morphologically is near to the posterior border of
the distal end of the girdle. The anterior border in this region in some species, as in FE. cornuta
(pl. 12, fig. 129), sometimes bears a notch which marks the attachment area where the anterior
end, possibly the anterior horn, of the posterior schizont is attached to the body of its sister cell,
the anterior schizont. It may well be that this notch in the posterior border is due to the same
cause, the final attachment of the two parting schizonts (Kofoid and Swezy, 1917).

502 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The tentacular recess is exceptionally deep in this species, reaching to the middle of the body,
where it has a width of 0.16 transdiameter in the upper 0.4 of its length. Below this it flares
in a campanulate outline beneath the left flap. The prod in the single individual seen was
quiescent and apparently contracted. Its total length in this condition was 0.4 transdiameter.
The smooth cylindrical shaft formed 0.5 its length and the ellipsoidal knob whose diameter was
1.5 times that of the shaft formed the other 0.5. There was no terminal stylet and no circular
wrinkles were noted, but a sheath of longitudinal fibrillae lies near the periphery of the shaft.

The ocellus is of the compound type consisting of a group of about seven subspheroidal,
transparent, hyaline lenses crowded in a loose mass opposite the intercingular region of the
suleus to the left of the flap. Their total volume is about the same as that of the single lens of
such species as EF. richardi, of approximately the same dimensions of body.

The pigment mass itself is black, irregularly lobed, and without fine processes. Twelve
droplets of similar pigment are distributed in the peripheral plasma across the equatorial region
of the ventral face. The core of the mass is an ellipsoidal (?) body, not fully exposed, extending
beyond the anterior end of the pigment mass. It is of a dark yellow ochre color. As a result
of the dispersal or absence of integration of lenses and pigment mass the ocellus extends for a
distance of 0.5 transdiameter obliquely anteroposteriorly on the left ventral face of the body.
The largest group of dispersed granules lies adjacent to the mass of lenses.

The nucleus is spherical, very hyaline, shows no trace of moniliform chromatin threads and
is located in the left anterior region, extending far into the epicone. There are two pusules
located respectively at the anterior flagellar pore and at the right of the tentacular recess. Both
are linear and bifurcated and their distal ends almost coalesce. Several smaller detached
vacuoles filled with a pinkish fluid similar to that in the pusules are present near the girdle on
the ventral face.

The general color is a glaucous hyaline grey with a greenish tinge imparted by the peripheral
vacuoles, which are rather large, ellipsoidal to linear in form, attaining a length of 0.2 trans-
diameter posterodorsally. More ellipsoidal or pyriform types appear on its ventral surface and
a birfureating. dendritic form was observed in the posterior part at the right of the sulcus. The
periphery is thickly strewn with minute grey granules which have neither the color nor the
consistency of the pigment grains.

Dimensions.—Lenegth, 111/; transdiameter, 88; diameter of nucleus, 45+.

OccURRENCE.—One individual was taken ina haul of a No. 25 silk net made
August 10, 1917, one mile off La Jolla, California, from 50 meters to the surface
and in a surface temperature of about 22° C. It occurred in the same catch
with £. hispida and another undetermined species of Erythropsis.

ComPparisons.—This species belongs to the subgenus Polyopsidella, but is
unique in the subgenus in the degree of dispersal or lack of integration of the
parts of the ocellus. The lens is not only organized in the largest number of
parts but it is also most loosely assembled. The pigment mass is more deeply
lobed and many more detached pigment granules are dispersed in the cytoplasm
than in any other species in the genus. It is also unique in the presence of the
anteriorly directed projection at the right of the sulcus over the intercingular
gap.

The capitate form of prod links it with #. pavillardi, but it differs from
this species in all other features. The divided lens is most like that of F. hispida
or of Pouchetia juno. On the whole, next to H. exrtrudens, it is the most highly
specialized species in the genus, though not the most aberrant one.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 503

It might appear that this was a contracted individual of some other species
with the ocellus in disintegration. However, the fact that in our experience this
organ persists longer than any other structure after cytolysis, and the lack of
any evidence that it disintegrates im situ prior to cytolysis, lead us to conclude
that the lobed structure of the elements of the ocellus is not a mere artifact.

Erythropsis minor sp. nov.
Plate 12, figure 131; text figure SS, 9

DraGcnosts.—A small species with stout, pyriform, ventrally arched body;
tapering hypocone; girdle displaced 0.45 transdiameter; ocellus 0.5 transdiam-
eter in length with red core; lens and black melanosome each simple, hemi-
sperical; prod short, tapering, with very short stvlet. Length, 48. Pacific off
La Jolla, California, July, August.

Descriprion.—Body stout pyriform, asymmetrical, its length (excluding tentacle) 1.4 trans-
diameters at the widest part which is at the anterior end of the hypocone. Ventral surface
coneave, dorsal convex. Dorsoventral diameter 0.88 transdiameter. Epicone relatively large,
its length, at right of suleus, 0.5 transdiameter. There was no apical horn. Owing to the large
size and protuberance of the ocellus the epicone on the left ventral region is scarcely exposed
at all in ventral view and, as a whole, is pushed to the right and has little dorsal surface. The
hypocone is widest a short distance below the girdle and contracts distally in an angle of about
30° to a reunded asymmetrical antapex. The right side is the longer, but the appearance of
asymmetry is increased by the obliquity of the point of view in the drawing. It was less evident
in other views’and disappeared entirely as the animal rounded up prior to cytolysis.

The girdle is peculiar in not completely encircling the body and in having its proximal end
almost at the anterior end at the left shoulder fully 0.25 transdiameter in the horizontal direction
from its distal end. It descends rapidly in a left spiral so that the intercingular displacement
is about 0.5 transdiameter in the vertical direction. The furrow has a fairly uniform width
throughout of 0.09 transdiameter. Its lower margin extends considerably beyond the upper,
and its trough is rather deeply indented. The transverse flagellum extends almost to the end
of the girdle and arises from the anterior flagellum pore immediately in front of the lens. No
paracingular grooves or bands were noted.

The suleus begins near the center of the epicone, runs to the left to its junction with the
girdle. It turns sharply to the right, following closely the contour of the ocellus, and joins the
distal end of the girdle at the level of the lower edge of the melanosome, and extends directly
posterior to the antapex. Its vertical displacement is 0.45 transdiameter, but the length of the
oblique intereingular region is more than 0.5 transdiameter. It is a narrow channel throughout,
but opens internally in the antapical region into the tentacular recess. This is very short, 0.27
transdiameter in length, and is broadly campanulate in form, its distal opening being 0.4
transdiameter across. -

The prod is a slender regular conical structure of 10° with a rounded tip and minute terminal
stylet asymmetrically located. It is not quite axial in position and inclines ventrally about 10°
from the major axis. Its length when (fully?) extended was 0.75 and when contracted 0.4
transdiameter. No trace of longitudinal or circular fibers or of surface granulations was noted.
A distinet longitudinal flagellum was found in this species. It persisted for some time, was
noted in various positions of the body, and was active in propulsion of the body. It takes its
origin from the posterior flagellar pore located on the dorsal wall on the right side of the
tentacular recess behind and to the right of the prod a short distance within the recess. It was
about twice as long as the prod.

504 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

The ocellus is relatively very large, its length is 0.55 transdiameter and its main axis inclines
45° to the right and ventrally from the major axis of the body. It protrudes considerably
beyond the contour of the body, especially in ventral view, and crowds the intercingular sulcus
anteriorly and the anterior flagellar pore almost to the anterior margin. The lens somewhat
exceeds a hemisphere, its diameter is 0.35 transdiameter. It is composed of concentric laminae
with a brilliant iridescence of spectral colors. The pigment mass is also regularly hemispherical
without lobes or detached granules and receives the base of the lens in its flattened side. The
black melanosome encloses a rather large coral-red core which shines through the thin layer of
black pigment.

The nucleus is a very elongated ellipsoid placed transversely across the equatorial region.
Its major and minor axes are 0.75 and 0.33 transdiameter respectively in length. It is possible
that it is in transformation prior to mitosis. No chromatin net and perinuclear zone were noted.
Pouch-shaped pusules with pinkish contents arise from the two flagellar pores. They are of
equal size and 0.25 transdiameter in length. No food balls or vacuoles or chromatophores were
found. Several greenish globules lie near the suleus on the ventral face and a number of minute
greenish vacuoles were scattered in the peripheral plasma. The general color was a pearl grey.

Dimenstons.—Length, 48; transdiameter, 35; length of nucleus, 26; length
of extended (?) tentacle, 26; length of ocellus, 19.

OccuRRENCE.—T wo individuals seen. These were taken with a No. 25 silk
net in the Pacific Ocean off La Jolla on July 20 and August 13, 1917, respec-
tively. The hauls were made from depths of 80 and 83 meters to the surface and
in surface temperatures of 20°6 C and 21°7 C respectively.

Activitres.—The individuals seen were not as active as those of EH. extrudens
or £. pavillardi, and the tentacle was subject to only feeble contractions as
observed by us, although there was no evidence that this inactivity was due to
the approach of cytolysis.

Compartsons.—This is the smallest species of the genus. It is possible that
it is a juvenile stage of some other form, although the morphological evidence
for structural transformations with growth as the individual grows older are
shght among dinoflagellates. It is nearest to FE. cornuta (Schiitt) in structure,
but is not only smaller, 48 as compared to 104“, but has a different type of
prod, tentacular recess, shape of body and nucleus, and lacks the apical horn.

The position of the longitudinal flagellum at the right side of the tentacular
recess and behind the prod is confirmed by the presence of the posterior pore.
and pusule. In Schiitt’s figure (1905, pl. 26, fig. 96) of FE. cornuta the posterior
flagellum is represented as arising at the base of and ventral to a spherical
structure which we interpret as the capitate end of the prod. The flagellum
figured by Schiitt is remarkably stout and peculiarly wavy. It is possible that
its origin is correctly figured; if so, the location of the posterior flagellar pore
differs remarkably in different species of Erythropsis. It is also possible that
its origin is dorsal to this tentacular knob, not ventral as figured. If so, this
location is homologous to that in #. minor. It is possible that the extreme
thickness of flagellum figured by Schiitt is due to contraction and may not
represent a fraved-out, axial tentacular fiber exposed by partial cytolysis, as its
structure figured by Schutt might suggest. The undoubted presence of the

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 505

longitudinal flagellum in this species precludes all possibility that the tentacle
represents in Hrythropsis a modified form of the longitudinal flagellum of other
Gymmnodinioidae.

Erythropsis pavillardi nom. sp. nov.
Plate 12, figure 133; text figures SS, 3, 5

Erythropsis agilis, Pavillard (1905), pp. 48-49, pl. 3, fig. 1.
E. agilis, Fauré-Fremiet (1914c), in part, pp. 27-47, pl. 1, text figs. 1, 3-12.

D1aGnosis.—Small to medium sized species with ellipsoidal body, its length
1.3 transdiameters, curved apical horn; girdle displaced 0.8 transdiameter ; pro-
tuberant ocellus, with hemispherical lens; flattened brownish-black pigment
mass with red core; elongated, hispid, cylindrical tentacle attaining five times
the length of body. Length, 55-82». Mediterranean at Cette, October; Croisic,
west coast of France, September; Pacific, off La Jolla, California, July.

Descriprion.—The body is quite regularly ellipsoidal, its length 1.3 to 1.5 transdiameters;
dorscventral diameter slightly less than the transverse. The epicone is a low cone of about 120°
with a height of about 0.5 transdiameter, except near the distal end of the girdle, where it slightly
exceeds 0.75 transdiameter, or 0.5 the length. Its diameter at the base is about 0.8 transdiameter
of the body. Its apex is rounded and bears a short, sinistrally directed, oblique apical horn
standing at an angle of 30°-45° from the vertical. It has the appearance of protoplasmic
undulations and has been figured by Pavillard (1905) and Fauré-Fremiet (1914) as carrying
a median flagellum. This is either the displaced transverse flagellum, or is an appearance due
to local protoplasmic undulations. Our observations are not conclusive on this point, but favor
the latter view. The horn is retracted as cytolysis approaches. The hypocone forms about 0.75
of the total body, is somewhat more rotund on the right, and has the contour of a hemisphere in
the antapical region.

The girdle forms a descending left spiral, descending steeply at its distal end to a total
displacement in the intercingular region of 0.45 of the total length of the body or at least 0.66
transdiameter. In Pavillard’s figure (text fig. SS, 5) there is a considerable displacement of
the dorsal side. The girdle almost completely encircles the body. The furrow is broad and
shallow, widening slightly beyond the anterior flagellar pore locatd above the ocellus. It is
uniform in width thereafter, but constricts to a narrow slit as it enters the suleus. No attach-
ment area was noted at its distal end. The transverse flagellum extends at least half way around
the body. No longitudinal flagellum was detected. An anterior paracingular line is clearly
defined, with a flattened space equal to the furrow in width between it and the furrow. No
posterior paracingular line was noted.

The suleus is a narrow groove curved around the right side of the relatively large ocellus,
extending as a narrow slit for a short distance below it and then widens out into the deep,
axially located, campanulate, tentacular recess, which extends anteriorly for a distance of 0.35
of the total length of the body. The extension of the suleus anteriorly upon the epicone is
indicated by the location of what seems to be the transverse flagellum thrown forward to the
apex from the anterior flagellar pore. Pavillard’s (1905) figure suggests this also. There is,
however, a possibility that the margins of the suleus are here contractile. The tentacle is
extraordinarily large in this species. When fully extended it is a fairly uniform cylinder
attaining five times the length of the body. Pavillard (1905) figures it with a uniform diameter
of 0.2 transdiameter when fully extended. We find it smaller (0.16—-0.18 transdiameter) than
this when contracted to one-fourth that length. When extended it is fairly uniform in caliber

506 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

throughout, but in contraction it swells out within the tenacular recess, and at the distal end to
such a degree that the latter becomes somewhat capitate. There is no terminal stylet, the distal
end being broadly rounded. There is a distinct axial, longitudinal strand, the retractor fiber
and a series of equidistant cireular fibers, the protractors. The prod was coarsely granular or
hispid on its surface in Pavillard’s specimen, but not in ours.

The ocellus lies to the left of the intercingular region of the suleus, the anterior 0.8 of which
it crowds to the right. Its total length is 0.55 transdiameter and the axis of the lens is about
45° from the major axis. The lens is hemispherical, as exposed, iridescent, and is buried rather
deeply in the black-pigment mass. This is flattened, with its long axis passing obliquely postero-
ventrally. It is somewhat more voluminous or swollen on the ventral and sinistral sides of the
lens. No colored core was visible in our specimen, but Pavillard figures a yellowish-brown tint
in its center. The ocellus as a whole is more than usually protuberant.

The nucleus is ellipsoidal (spherical in end view) and lodged far anterior in the epicone in
the right dorsal region. Its major and minor axes are respectively 0.65 and 0.5 transdiameters
in length. It is hyaline and does not exhibit the moniliform chromatin network usual in the
dinoflagellates. The pusule arises from the anterior flagellar pore and extends posteriorly at
the right of the ocellus toward the distal end of the girdle, with another branch running poster-
iorly from the pore along the dorsal side of the tentacular recess. In Pavillard’s figure the two,
posteriorly located. yellow bodies are probably food pellets. None occurred in our specimen.
There were no peripheral vacuoles formed during our observations. The plasm was at all times
a translucent, hyaline, dull opaline green, shading into variscite green. Fauré-Fremiet’s (1914c)
specimens had a faint pinkish tone.

Direnstons.—Length of body, excluding prod, 82H; including extended
tentacle, 530; length of prod, extended, about 450; contracted, 90#; transdi-
ameter, 57; dorsoventral, 60; diameter of lens, 17. Pavillard’s specimen was
smaller, length, 554. Fauré-Fremiet gives a range of 50 to 100 in total length
of body.

OccuRRENCE.—A single individual was taken off La Jolla, California, July
30. 1917, in a haul with a No. 25 net from a depth of 80 meters to the surface,
made 2.5 miles offshore in a surface temperature of about 21° C. Pavillard
(1905) observed a single individual taken in plankton from the Etang de Thau,
a small bay from the Mediterranean at Cette, France, on October 19, 1904, in
surface temperatures of 14°8 C. Fauré-Fremiet records (1914) a score of
specimens from Croisic, on the west coast of France.

Actrvities.—The individual observed by us was extraordinarily active.
When first brought into view it was circling without noticeable rotation in anti-
clockwise spirals about six times its length in diameter. During this time and
when at rest its prod underwent ceaseless rhythmical contractions, externally
contracting to a length about equal to that of the body and extending as
much as five times its length. The rapidity of contraction varied within short
intervals. A number of records were made of the number of these contractions
for given periods, as follows: 51 contractions in 30 seconds, or 1.7 per second;
27 in 10 seconds, or 2.7 per second; 35 in 20 seconds, or 1.7 per second; and 14
in 10 seconds, or 1.4 per second. These records were made at consecutive inter-
vals during the course of a few minutes. They average 2.2 per second. The
contractions slowed down and stopped some time before cytolysis occurred. It
remained active for nearly six hours.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 507

SynonyMy.—Pavillard (1905) figures as EF. agilis Hertwig a small species
about half the size of Hertwig’s, with more smoothly contoured body, more
conical epicone, longer apical horn, more displaced girdle, and a black instead
of a red pigment mass. In view of the degree of speciation detected by us in
the genus and because of these differences above noted it seems probable that
Pavillard had a different species from that found by Hertwig (1884) at Sor-
rento. It appears to be similar to one we have found at La Jolla. We take
pleasure in naming it for Professor Pavillard, the investigator of the Dino-
flagellata of the Mediterranean.

The Erythropsis which Fauré-Fremiet (1914c) discovered at Croisie,
France, in 1913, and called EF. agilis Hertwig, appears to be identical with that
figured by Pavillard (1905) from Cette. We have elsewhere (1917) given the
grounds upon which we reject Fauré-Fremiet’s reversed orientation, origin and
reversed direction of the transverse flagellum and the longitudinal flagellum
emerging in the anterior loop of the sulcus from the apex. The red core or
‘*Hirvthrosome’’? was more in evidence in his material than in ours, but in all
other essential features except for those noted in our paper (1917) the simi-
larity is sufficiently close to justify the inclusion of the Erythropsis from Cette,
Croisic, and La Jolla in one species.

CoMPARISONS.—Our specimen is not wholly in agreement in all details of
structure with that found by Pavillard. Its girdle is apparently not so steep
dorsally, its furrow is wider, its prod is not hispid and becomes capitate on
contraction, and it is 82” in length, while Pavillard’s was only 554. However,
the lens is the same, the pigment mass similar in form, though lacking the vellow
to brown core as observed by us, and the tentacle and apical horn are alike in
our two specimens in important respects. In view of the margin of difference
to be allowed in accounts of organisms so difficult to observe accurately as this
mobile genus, it seems best to accept these resemblances as indicative of specific
identity and attribute our differences to divergences of observation and record,
or to variation within the species.

FE. pavillardi differs, in certain distinctive features, from EF. agilis Hertwig,
to which Pavillard (1905) referred his specimen, the third individual seen up
to that time in the whole genus. The foremost of these is the red-pigment mass
of E. agilis and the black one with yellowish-brown center of FE. pavillardi. In
addition Hertwig’s species is about 100 in length, while Pavillard’s specimen
was 55 and ours 824. The antapex is truncate in F. agilis and rounded in £,
pavillard:. In addition there are minor differences in shape of the epicone,
course of the girdle, and exposure of the lens. As will be seen on comparison
of the figures of all the species of the genus drawn to the same scale (text
fig. SS), the distinctions between them are noticeable.

E. pavillardi belongs to the subgenus Hrythropsis in restricted sense and is
close to E. minor, but differs from it in longer prod without stylet and more
rotund body of larger size. It is much smaller than £. cochlea and has a flat-
tened instead of rotund pigment mass.

ou
oS
(oe)

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Erythropsis richardi sp. nov.
Plate 12, figure 134; text figures SS, 10; VV

Dracnosis.—A large rotund species; body broadly ellipsoidal; its length 1.25
transdiameters; with low conical apical horn; girdle displaced 0.3 transdiam-
eter: ocellus protuberant ventrally; lens compound; subhemispherical in two
distinct sections; pigment mass slightly lobed with red core; prod (contracted)
stout clavate with short asymmetrical stylet. Length, 106 to 112”. Pacific off
La Jolla, California, August.

DescripTion.—The body is very stout, rotund ellipsoidal, its length 1.18 to 1.25 transdiam-
eters, according to the degree of contraction. Dorsoventral diameter equal to the transverse,
left side more rotund and slightly longer. It is widest near the middle but in contracted con-
dition it tends to bag out posteriorly and flatten anteriorly. Epicone low, flattened, its length
middorsally, excluding horn, 0.1 transdiameter. Near the distal end of the girdle it extends
posteriorly on the ventral side to nearly 0.5 the total length. The apex is almost squarely
truncate with a small low conical apical horn whose height is about a girdle’s width. The total
volume of the epicone is less than 0.16 of that of the body. The hypocone is quite rotund, with
rounded, indented, asymmetrical antapex with the left side the longer.

The girdle is almost flat for 0.75 of its course. It ascends slightly from the midventral
flagellar pore to pass above the ocellus, then continues a horizontal course across the left and
dorsal sides. At the right side it descends posteriorly at an angle of 45° across about 45° of
the right ventral quadrant, then turns abruptly posteriorly for about 0.25 transdiameter, then
turns again almost at a right angle and proceeds thence to its junction with the sulcus. No
attachment area was noted at its distal end. The furrow is deeply incised and is bordered both
anteriorly and posteriorly with a paracingular groove. The precingular groove originates about
a furrow’s width anterior to the proximal end of the girdle, increases its distance from the
furrow to two furrows’ widths in the dorsal region and to three or four at the distal end of the
girdle. The postcingular groove is quite uniformly separated by a furrow’s width from the
girdle and has a ragged appearance. The paracingular bands or strips between grooves and
the girdle are clear and free from surface markings and vacuoles and their surfaces are flattened
or even slightly concave. They are clearly defined in this species.

The suleus is little disturbed by the crowding of the ocellus upon it, and is thrown into only

a slight sigmoid curve by its presence. It appears to extend upon the epicone to the base of the
apical horn and probably to the left of it, is closely appressed in the intercingular region, and
is without lateral overlap, being in fact open by a rather wide gap into the tentacular recess.
This cavity extends into the axis of the body for 0.45 of its length and flares widely to 0.5
transdiameter at the antapical region (text fig. SS, 10).
' The prod or tentacle is a stout clavate structure, withdrawn within the recess in the resting,
contracted condition in which its greatest diameter, located near its middle, is 0.17 transdiameter.
It is axially located, posteriorly directed, and tapers distally to a blunt point which bears a
minute, asymmetrically placed, terminal stylet. When feebly extended it takes the form of a
slender asymmetrical rod continued posteriorly from a swollen base and when completely re-
tracted rounds up into a capitate knob (text figs. SS, 10) with or without a tip. There is a
faint axial retractor fiber. No circular fibers are evident and the external surface is without
granulations.

The ocellus is of the compound type, though less evidently so than any of the species of the
subgenus Polyopsidella. It is displaced well to the left, about 0.17 transdiameter to the left of
the sulcus with its main axis parallel to that of the body. It protrudes strongly on the ventral

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 509

surface. The lens is composed of two flattened superposed iridescent hemispheres, the front one
0.3 and the rear one 0.25 transdiameter in diameter, but not deeply imbedded in the pigment
mass. This mass is broadly ellipsoidal, 0.35 transdiameter in length and slightly lobed. Its
core is of a bright coral-red color which shines through the enveloping black pigment.

After cytolysis the ocellus (text fig. VV, 2) persists for a time. The melanosome contracts
and exposes a third disklike segment of the lens of the same hyaline nature as the second seg-
ment. It is immediately against this that the coral-red core lies. The elements of the ocellus
slowly waste away by peripheral solution and fragmentation, the pigment of the melanosome
and the red globules of the core persisting longest.

The large spheroidal nucleus lies in the left anterior part of the body dorsal to the ocellus.
It showed no beaded chromatin thread and was very hyaline, but after cytolysis it was seen to
have an exceedingly fine beaded chromatin network and a distinet outer perinuclear membrane
and inner hyaline zone. No pusule or food balls were noted. The peripheral plasma was filled

‘shortly before cytolysis with a layer of small, uniform, rather closely packed, greenish vacuoles,
present everywhere except in the paracingular bands. The general color was a pale glaucous
green. There were no chromatophores.

tA
‘das ‘Ay jsip
‘dvo ‘pur =o")
“das “Ky *uoid- == tiple |

Fig. VV. Details of ocellus and tentacle of Erythropsis richardi. 1. Ocellus as revealed by cytolysis.
Abbreviations: irid. cap., iridescent stratified cap; dist. hy. segt., distal hyaline segment exposed when in place
in the body; pros. hy. segt., proximal hyaline segment, imbedded in the pigment mass in the body but exposed
by contraction or solution of the pigment at cytolysis; core., coral-red core within the pigment; pig., black
pigment mass or melanosome. 2. Dorsal view of body showing retracted tentacle in capitate form. 3. Postero-
sinistral view exposing opening of tentacular recess and contracting tentacle. 4. Contracted tentacle in lobed
state seen from the dorsal side. X 500.

Dimensions.—Length, 106-112; transdiameter, 85; diameter of nucleus,
40+; of lens, 27+; of pigment body, 30+.

OccuURRENCE.—T wo individuals seen, taken in the plankton 3 and 4 miles
off La Jolla, July 26 and 27, 1917, in hauls of a No. 25 silk net from a depth of
80 meters to the surface in surface temperatures of 21°4 C and 21°7 C.

Named for Professor Richard Hertwig of the University of Miinich, the
discoverer of Hrythropsis. The preoccupation of the specifie name hertwigi
by a slip of the pen on the part of Jollos (1910, p. 203) precludes the use of the
patronymic name of this eminent protozoologist as a specific name by us in
Erythropsis.

Activities.—One individual was kept under observation from 11 a.m. till
2 p.M., when it underwent cytolysis. During this time it was feebly active,
moving in irregular anticlockwise spirals in an intermittent fashion. The ten-
tacle was not at any time in intense activity such as that shown by FE. pavillardi.

510 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

A few feeble strokes with an extension of the tip only a little beyond the body
were repeated from time to time. There was other evidence of a moribund
condition. These observations suggest that the tentacle is small and less active
in this species than in many others of the genus.

CoMPARISONS.—This species belongs to the subgenus Polyopsidella because
of its compound ocellus, but is most like the subgenus Hrythropsis in that its
compounding is least marked, being shown by three subdivisions of the lens and
shght lobing of this pigment mass.

It is the only species with compound ocellus and also an apical horn. Its
paracingular grooves and beads are more marked than usual in the genus. Its
small, uniform, crowded peripheral vacuoles resemble those of EL. cochlea, but
are not appressed into polygonal fields as in that species. Its tentacle when
extended resembles that of H. cornuta (Schutt), but its proportions, ocellus,
girdle, and apical horn are quite different from those of that species.

Erythropsis scarlatina sp. noy.
Plate 12, figure 128; text figures RR, 2; SS, 4

DraGNnosis.—Large species; body elongated subcylindrical; its length 1.7
transdiameters; epicone reduced; its diameter 0.5 transdiameter: no apical
horn; sides furrowed; girdle displaced distally beyond the middle; tentacular
recess oblique; prod sinuous tapering; directed obliquely ventrally; no stylet;
ocellus compound; lens of five segments in a row; black-pigment mass lobed;
body extensively streaked and mottled with scarlet. Length, 104». Pacific off
La Jolla, California, August.

DEScRIPTION.—This species is unique in form, structure, and color. The body is elongate
subeylindrical, somewhat truneate at both ends. Its length is 1.7 transdiameters and its dorso-
ventral diameter is slightly greater than the transdiameter. The epicone is reduced to an apical
button whose diameter is only 0.5 transdiameter and altitude only 0.07, except in the distal
quadrant in which it forms a long triangular process extending posteriorly along the right side
of the suleus for a full transdiameter from the apex. The center of the epicone is filled with a
lone, rounded terminal knob which probably represents the apical horn. The hypocone forms
over 0.9 of the body, its length at the anterior flagellar pore being 0.9 of the total length.
Anteriorly its shoulders are rounded in abruptly to the girdle, about twice as far on the right
as on its left side. The left margin is quite regularly convex while the right and dorsal are
straight or even somewhat concave. The antapex is truncate, its outline being somewhat sinuous
as a result of the posterior terminations of the lateral furrows. The sides of the hypocone are
deeply scored by parallel grooves which run from the anterior shoulders to the postmargins.
There are five of these on either side of hypocone. They are about equidistant and are deepest
near the middle of the body.

The girdle forms a flat spiral around the button-like epicone with little deflection in its
proximal 0.75. At the beginning of the distal quadrant it turns posteriorly at an angle of 45°,
and steepens to 15° from the vertical near its distal end which is in consequence carried poster-
iorly to the middle of the body with a total displacement of 0.7 transdiameter. The furrow is
very narrow, only about 0.05 transdiameter wide, and lies in the hollow of a deep depression.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA o11

The anterior flagellar pore lies in its proximal end a short distance in front of the lens and
the transverse flagellum runs less than 0.75 of the length of the girdle. No paracingular grooves
or bands were noted, and no attachment area detected.

The suleus begins on the epicone above the girdle where it partially encircles the terminal
knob, and after its junction with the girdle it passes in almost a straight line posteriorly. It is
not displaced to the right by the deeply buried ocellus which somewhat underlies its inter-
cingular region. It is a narrow slit closed by the overlapping right flap which forms a sharp
salient angle at the upper end opposite the proximal end of the girdle. Posteriorly it opens out
into the large posteroventral tentacular recess. This cavity has an extreme length at the ventral
surface of 0.3 total length of the body and about half this on its dorsal side. From the middle
of its sloping anterior surface springs the prod.

The prod, owing to the fact that the tentacular recess is not axially located but lies in the
ventral half of the body and has a sloping anterior wall, projects ventroposteriorly at an angle
of about 15° from the axis. It has a total length of about 0.75 transdiameter and projects for
about half its length beyond the margin of the recess. Within this cavity it has a thickened
shaft about 0.15 transdiameter in thickness, a constricted base, a somewhat sinuous course, and
is reduced to about one-third of this diameter in its extruded part which likewise has a sinuous
course. Its tip is blunt, without stylet and no cireular or axial fibers were noted. No longi-
tudinal flagellum was observed.

The ocellus is of the compound type. It consists of a segmented lens and lobed pigment
mass. Its total length is 0.65 transdiameter, and its major axis is somewhat oblique to that of
the body. The lens consists of five rounded disks, appressed in a linear series decreasing a trifle
in size posteriorly, set shghtly oblique to the main axis and parallel to and beneath the suleus.
Their color is a clear glaucous blue with a tinge of yellow. Their diameter is 0.15 to 0.18 trans-
diameter and their thickness one-third to one-half their diameter. They rest lightly along a
part of the flattened face of the irregularly hemispherical pigment mass, and not in continuation
of its axis as is usually the case in the relation of lens and pigment. The pigment mass is bluntly
lobed in several regions and a small detached mass lies anterior to the line of lenses. The pig-
ment mass proper consists of an outer melanosome of black pigment and an inner core of reddish-
brown substance almost entirely concealed by the darker material.

Pigment is found elsewhere in the body of this remarkable animal distributed in a very
characteristic and peculiar fashion. The periphery of the epicone and shoulders of the hypocone
are covered with a mantle of brillant Brazil-red pigment distributed in the peripheral plasma
as a mottled reticulum formed of finely divided granules. These red reticulations extend
posteriorly down the ventral face on either side of the suleus and become continuous with a
radial network of similar pigment spreading in all directions from a denser center near the
base of the tentacle. Several droplets of dark clear rose-red pigment lie on the left side of the
suleus posterior to the ocellus, and a single large droplet of the same sort is found near the
proximal end of the girdle. Several linear masses of reddish-black pigment lie in the axis of
the distal part of the tentacle. This pigment appears, in the main, to be distributed in regions
of presumably greatest tension and most active oxidative processes, namely, the base of the prod,
and along the girdle and suleus. There is no indication that this pigment is derived from the
food of the organism. f

The ellipsoidal nucleus has major and minor axes with lengths of 0.55 and 0.35 transdiameter
respectively and lies with the major axis at an angle of 45° to that of the body, far anterior.
No chromatin net was detected in its hyaline interior. There were no chromatophores or food
balls, rhabdosomes or peripheral vacuoles. No pusules were noted. The eytoplasm was highly
translucent of a clear pearl-grey color, shading into a glaucous blue in the margins and along
the lateral grooves.

512 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Dimenstons.—Length, 104; transdiameter, 59«; length of tentacle, 48+; of
ocellus, 361,

OcCURRENCE.—A single individual was taken in a haul.of a No. 25 silk net
5 miles off La Jolla, California, on August 21, 1917, from a depth of 83 meters,
in surface temperature of about 22° C.

Activities.—The animal was not motile during the period of observation.
There was no indication that the lateral grooves were due to collapse, or ab-
normal, or moribund condition.

CoMPparIsoNn.—This is the most unique species of the genus in form, color,
and structure, being most divergent in all structural features, such as ocellus,
tentacle, and pigmentation. The lateral grooves recall those of Amphidiniwm
cucurbita and Gymnodinium puniceum in location, form, and number. No
other species of Erythropsis has any suggestion of such grooves, although indi-
cations of longitudinal lines of stress are hinted at in the tendency for periph-
eral vacuoles to take on longitudinally elongated forms. No other species of
Erythropsis has any finely distributed pigment outside of the pigment mass
and none has the divided lenses in a linear series, except EL. richardi, in which
there are only two segments to the lens. Owing to these structural features,
E. scarlatina stands apart from all other species as the most specialized repre-
sentative in the subgenus Polyopsidella, of which it is the type species.

SUMMARY

1. This monograph includes all known unarmored and free-living Dinofla-
gellata. It is based on a study of the marine forms of the San Diego region
made at the Marine Biological Station of the Scripps Institution for Biological
Research. It includes 223 species belonging to 16 genera.

2. The following genera are new: Protodinifer, Gyrodinium, Torodinium,
Pavillardia, Protopsis, Nematodinium, and Proterythopsis.

3. One hundred and seventeen species are new, distributed as follows in the
genera: Protodinifer, 1; Amphidinium, 12; Gymnodinium, 36; Gyrodinium,
23; Cochlodinium, 21; Torodinium, 1; Pavillardia, 1; Protopsis, 1; Nemato-
dinium, 2; Pouchetia, 12; Proterythropsis, 1; Erythropsis, 6; a total of 117 new
species. :

4, The Dinoflagellata have evolved from a primitive, biflagellated flagellate,
by differentiation of the two primitive, similar, anterior flagella. One becomes
ribbon-like, with short undulations, and is the transverse flagellum of the Dini-
feridia. The other flagellum becomes the longitudinal trailing flagellum by the
posterior migration of the flagellar pore to the midventral region. In the
Adiniferidea the flagella are differentiated but the pore has not migrated
posteriorly.

5. The unarmored forms are more primitive than the armored ones, the
Athecatoidae than the Thecatoidae in the Adiniferidea, the Gymnodinioidae
than the Peridinioidae in the Diniferidea.

6. The new genus Protodinifer is a primitive form with anterior, differen-
tiated flagella, and partial girdle feebly developed. It shows affinities to the
Adiniferidea and suggests the origin of both Adiniferidea and Diniferidea from
unarmored, ancestral forms allied to it.

7. The two flagella, transverse and longitudinal, with the two channels in
the surface of the body in which they lie, the girdle and sulcus, are superficial
organs in active contact with the environment, and are extensively modified in
an orthogenetic manner in the evolution of the genera, and in speciation within
the genera. j

8. The modifications consist of a progressive elongation of the girdle, with
accompanying torsion of the body in a left spiral up to four turns. There is
also a progressive torsion of the sulcus and its prolongation to the apex and
antapex, culminating in the genus Cochlodinium.

[513]

514 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

9. Structural differentiations of the areas bordering the girdle and sulcus,
with or without torsion, appear in the pseudopodia of Gymnodinium zachariasi,
the ephemeral (?) tentacle of G. pseudonoctiluca, the tentacle of Noctiluca, the
incipient prod of Proterythropsis, and the highly developed prod and its enclos-
ing chamber in Hrythropsis. There is also a tendency for pigment to aggregate
in the margins of the girdle, for the stigma to appear in the sulcus, and for the
ocellus to lie adjacent to the girdle.

10. There is an orthogenetic evolution of the ocellus in the genera Protopsis,
Pouchetia, Proterythropsis, and Erythropsis, by the integration of scattered
pigment granules and loosely aggregated lens bodies into a compact melano-
some enclosing a red sensory core at the base of concentrically laminated,
spherical lens.

11. Nematocysts are formed in Polykrikos and Nematodinium. They are
derivatives of the centrosome or cell center.

12. There is an extraordinary range in color of the Gymnodinioidae. The
simpler forms are green, yellow, or brown, while the colors of many of the more
complex ones are near the red end of the spectrum.

13. Holozoic nutrition occurs in most of the genera and is almost exclu-
sively prevalent in those of a higher type. The sulcus is the cytosome.

14. Noctiluca belongs in the Gymnodinioidae. It has a suleus, the so-called
atrium and rod organ, a rudimentary girdle, heretofore undetected, and the
transverse flagellum is present in a rudimentary condition in the so-called tooth.

15. The Cystoflagellata, as defined by Haeckel, should be reduced to contain
only Leptodiscus and Craspedotella, pending the analysis of their affinities when
their life history shall be discovered.

LITERATURE CITED

ADLER, C. F.
1752. Noctiluca marina quam praesidio D. D. Caroli Linnaei, publice ventilandam sistit
Carolus. Frid. Adler (Holmiensis, Upsaliae), 1752, Maji. in Linnaeus, C., Amoeni-
tates Academiceae, 3, 202-210, pl. 3.

ALLMAN, G. J.
1872. Notes on Noctiluca. Quart. Jour. Mier. Sei., (2), 12, 327-334, pl. 18.
1875. Recent progress in our knowledge of the ciliate Infusoria. Mon. Micr. Jour., 14,
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AMBERG, O.
1900. Beitriige sur Biologie des Katzensees. Naturf. Ges., Ziirich, 45, 57-136, pls. 1-4.

APSTEIN, C. J
1896. Das Siisswasser-plankton. Methode und Resultate der quantitativen Untersuchung
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1906. Pyrocystis lunula and ihre Fortpflanzung. Wiss. Meeresunters., Abt. Kiel, 9, 263-669,
pl. 10, 1 fig. in text.
1909. Die Pyroeysteen der Plankton-Expedition. Ergeb. Plank. Exp. Humboldt-Stiftung,
4, M. c., 1-27, pls. 1, 2, 3 figs. in text.

AURIVILLIUS, C.
1896. Das Plankton des Baltischen Meeres. Bihang Kgl. Svenska Vet.-Akad. Handl., 21,
No. 8, 1-82, pls. 1, 2.
1898. Vergleichende thiergeographische Untersuchungen itiber die Plankton-Fauna des Ska-
geraks in den Jahren 1893-1897. Kgl. Svenska Vet.-Akad. Handl., 30, No. 3, 1-427,
15 figs. in text.

BAcHMANN, H.
1907. Vergleichende Studien tiber das Phytoplankton von Seen Schottlands und der Schweiz.
Arch. Hydrob., 3, 1-91, 22 figs. in text.
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BatLey, J. W.
1850. Microscopical observations made in South Carolina, Georgia, and Florida. Smithson.
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Bairp, W.
1830. On the luminousness of the sea. Mag. Nat. Hist., 3, 8308-321, 3 figs. in text.

BaLBIANI, G.
1884. Les organismes unicellulaires. Jour. Microg., Paris, 8, 134-142, 249-257, 367-373,
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Bexar, K.
1915. Protozoenstudien. I. Arch. Prot., 36, 13-51, pls. 2-4, 3 figs. in text.

516 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Berou, R. S.
188la. Bidrag til Cilioflagellaternes Naturhistorie. Nat. Viden. Medd., Copenhagen, 1881,
60-76.
1881b. Der Organismus der Cilioflagellaten. Morph. Jahrb., 7, 177-288, pls. 12-16.
1882. Ueber die systematische Stellung der Gattung Amphidinium. Zool. Anz., 5, 693-695.
1884. Neue Untersuchungen iiber Cilioflagellaten. Kosmos, 1, 384-390.

BoLocHoNnzEw, E.
1902. Material for the study of the phytoplankton of the Volga according to investigations
from July 15 to September 4, 1901. Report Biol. Volga-Stat., 1901, 1-9. Russian.
1903. Beobachtungen tiber das Phytoplankton der Wolga im Sommer des Jahres 1902. Jbid.,
1903, 1-93, pl. 1. Russian.

BorGert, A.
1897. Beitrage zur Kenntnis des in Sticholonche zanclea und Acanthometridenarten vorkom-
menden Parasiten (Spiralkérper Fol. Amoebophrya Képpen). Zeitschr. wiss. Zool.,
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1911. Eine neue Form der Mitose bei Protozoen nach Untersuchungen an marinen Ceratiwm-
Arten. Verh. Intern. Zool. Kong., Graz., 1910, 408-418, 5 figs. in text.

Bostock, J., and Riey, H. T.
1855. The natural history of Pliny, translated by John Bostock and H. T. Riley. Book 2,
chap. 3, p. 143. Observations on phosphorescence.

BLOCHMANN, F.
1884. Bemerkungen tiber einige Flagellaten. Zeitschr. wiss. Zool., 40, 42-50, pl. 2.

BoviEr-LAPIERRE, E.
1886. Note sur les chaines de Péridiniens appartenant au genre Polykrikos. C. R. Soe. Biol.
Paris, 8, 535-536.
1888. Nouvelles observations sur les Péridiniens appartenant au genre Polykrikos. Ibid.,

5, 579.
Branpt, K.
1905. Zur Systematik der koloniebildenden Radiolarien. Zool. Jahrb. SuppL., viii, 311-352,
pls. 9-10.

BrRIGHTWELL, T.
1857. On self-division in Noctiluca. Quart. Jour. Mier. Sci., 5, 185-191, pl. 12.

Brucutere, M.
1791. Tableau eneyclopédique et méthodique des trois régnes de la nature. Contenant
l’helminthologie, on les vers Infusoires, les vers intestins, les vers mollusques, ete.
(Paris, Panckoucke), 591 pp., 96 pls.
Buscu, W.
1851. Beobachtungen tiber Anatomie und Entwicklung einiger wirbellosen Seethiere (Berlin,
Hirschwald), viii + 143 pp., 17 pls.
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figs. 1-10. Anonymous review.
ButscHInsky, P.
1897. Die Protozoan-Fauna der Salzsee-Limane bei Odessa. Zool. Anz., 20, 194-197.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 51

~)

Biscay, O.
1873. Hiniges tiber Infusorien. Arch. mikr. Anat., 9, 657-678, pls. 25-26.
1885a. ‘‘Dinoflagellata’’ in ‘‘Protozoa’’ (1880-89), 7n Bronn, ‘‘Klass. u. Ordn. des Thier-
reichs,’’ 1, 906-1029, pls. 51-55, 10 figs. in text.
1885b. Einige Bemerkungen tiber gewisse Organisationsverhaltnisse der sog. Cilioflagellaten
und der Noctiluca. Morp. Jahrb., 10, 529-577, pls. 26-28, 4 figs. in text.
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CAULLERY, M.
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Cavers, E.

1913. The inter-relationships of Flagellata and primitive Algae. New Phyt., 12, 28-36;

78-123, 177-187, 225-232, 10 figs. in text.
Cuarton,. E.

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143, 981-983, 5 figs. in text.

1907. Nouvel apereu sur les Blastodinides (Apodiniwm mycetoides n. g., n. sp.). Ibid.,
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1908. Note préliminaire sur trois formes nouvelles du genre Blastodinium Chatton. Bull.
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1912. Diagnoses préliminaires de Péridiniens parasites nouveaux. Jbid., 37, 85-93, 7 figs.
in text.

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1914b. L’autogenese des nématocystes chez les Polykrikos. Ibid., 158, 434437, 8 figs. in text.

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gen., 54, 157-194, pl. 9, 18 figs. in text.
CIENKOWSKI, L.

1871. Ueber Schwirmerbildung bei Noctiluca miliaris. Arch. f. mikr. Anat., 7, 131-139,
pls. 14, 15.

1872. Ueber Noctiluca miliaris Sur. Ibid., 9, 47-61, pls. 3-5.

CLAPAREDE, E., and LACHMANN, J.

1858-61. Etudes sur les Infusoires et les Rhizopodes. Mém. Inst. Genevois, 5, mém. 3, pp.
1-260, pls. 1-13, 1858; 6, mém. 1, pp. 261-482, pls. 14-24, 1859; 7, mém. 1, pp.
1-291, pls. 1-13.

Curve, P. T.

1894. Redogorelse for de Svenska hydrografiska undersdkningarne aren 1843-1894 under
ledning af G. Ekman, O. Pettersson, och A. Wikander. 11. Planktonunders6k-
ningar, cilioflagellaten och diatomacéer. Bihang Kgl. Svenska Vet.-Akad. Handl.,
20, Afd. 111, No. 2, pp. 1-16, pls. 1, 2.

518 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

CocKERELL, T. D. A.
1907. The Protozoa of the university campus. Univ. Colo. Studies, 4, 261-264.
1910. The fauna of Boulder County, Colorado. Ibid., 18, 227-256.

Coun, F.
1866. Neue Infusorien im Seeaquarium. Zeitschr. wiss. Zool., 16, 253-302, pls. 14, 15.

Coutii, B.
1912. Etude monographique sur les acinétiens. 11. Morphologie, physiologie, systematique.
Arch. Zool. exp. et gen., 10, 1-457, pls. 1-6, 111 figs. in text.

Conn, H. W.
1905. The Protozoa of the fresh waters of Connecticut. Conn. State Geol. Nat. Hist. Surv.,
Bull., 2, 1-69, pls. 1-84.

CunHaA, A. DA
1913. Beitrage zur Kenntnis der Protozoenfauna Brasiliens. Mem. Inst. Oswaldo Cruz, 5,
101-122, pls. 9, 10.

Dapay, E. :
1883. Ueber eine Polythalamie der Kochsalztumpel bei Déva in Siebenbiirgen. Zeitschr.
wiss. Zool., 40, 465-480, pl. 24.
1884. Adatok a Cilioflagellatak ismeretéhez. (véglénytani tanulmany). Ertek. Term. Kor.,
13, 1-16, pl. 1.
1888. Systematische Uebersicht der Dinofligellaten des Golfes von Neapel. Term. Fuz., 11,
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DAHLGREN, U.
1915. The production of light by animals. Jour. Franklin Int. Inst., Phila., 180, 513-538
711-727, 16 figs. in text.
1916. Idem, ibid., 181, 108-125, 8 figs. in text.

2

Datu Torre, K. W.

1885. Studien iiber die mikroskopische- Thierwelt Tirols. Infusoria Flagellata. Zeitschr.
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DANGEARD, P. A.
1888. Les Péridiniens et leurs parasiten. Jour. Botan., Paris, 2, 126-146, pl. 5.

Danysz, J.

1886. Contribution a l’étude de ]’évolution des Péridiniens d’eau douce. C. R. Aead. Sci.,
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DELAGE, Y., and H&rovuarp, E.

1896. Traité de zoologie coneréte. I. La cellule et les Protozoaires (Paris, Schleicher), 1,
xxx + 584 pp., 890 figs. in text.

Dresine, K. M.
1850. Systema Helminthum (Vindobonae, C. Gerold’s Sohn), 1, xiii + 679 pp.
1866. Revision der Prothelminthen. SB Math. Nat. Klasse kg]. Akad. Wiss. Wien, 52,
287-401.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 519

DoFLEIN, F.

1900. Zell und Protoplasmastudien. Erstes Heft; Zur Morphologie und Physiologie der
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ismem. Zool. Jahrb. Abt. f. Anat. u. Ont., 14, 1-60, pls. 1-4.

1901. Die Protozoen als Parasiten und Krankheitserreger nach biologischen Gesichtpunkten
dargestellt (Jena, Fischer), Ed. 1, xiii + 274 pp., 220 figs. in text.

1909. Lehrbuch der Protozoenkunde. Eine Darstellung der Naturgeschichte der Protozoen
mit besonderer Beriicksichtigung der parasitischen und pathogenen Formen (Jena,
Fischer), Ed. 2, ix + 914 pp., 825 figs. in text.

1911. Idem. Ed. 3, xii + 1048 pp., 951 figs. in text.

1916. Idem. Ed. 4, xiv + 1190 pp., 1198 figs. in text.

Doairt, V.
1906. - Beitrige zur Kenntnis der Peridineen. Mitt. Zool. Stat. Neapel., 18, 1-45, pls. 1, 2.

Dusarpin, F. ;
1841. Histoire naturelle des Zoophytes. Infusoires comprenant la physiologie et la classi-
fication de ces animaux et la maniere de les étudier a l’aide du microseope. Jn
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ERRENBERG, C. G.

1830. Beitrage zur Kenntnis der Organisation der Infusorien und ihrer geographischen
Verbreitung, besonders in Sibirien. Abh. Akad. Wiss. Berlin, 1830, 1-88, pls. 1-8.
Published separately in 1830 with additions.

1832. Ueber die Entwickelung und Lebensdauer der Infusionsthiere; nebst ferneren Bei-
triigen zu einer Vergleichung ihrer organischen Systeme. Jbid., 1831, 1-154, pls.
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1834a. Organisation in der Richtung des kleinsten Raumes. Dritter Beitrag zur Erkenntniss
grosser Organisation in der Richtung des kleinsten Raumes. J[bid., 1833, 145-336
pls. 1-11. Published separately in May, 1834, with additions, and pagination 1-192.

1834b. Das Leuchten des Meeres. Neue Beobachtungen nebst Uebersicht der Hauptmomente
der geschichtlichen. Entwicklung dieses merkwiirdigen Phinomens. Jbid., 1834,
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1836. Zusitze zur Erkenntniss grosser organischer Ausbildung in den kleinsten thierischen
Organismen. Jbid., 1835, 151-180, pl. 1. Published, 1836.

1838. Die Infusionstierchen als vollkommene Organismen (Leipzig, Voss), xii + 547 pp.,
pls. 1-64.

1853. Ueber einige neue Materialien zur Uebersicht des kleinsten Lebens. 1. Das Leben in
der Wassertriibung des Rheins; II. Neue rothe Wusten-erde aus Afrika; III. Ueber
einen neuen Meteorstaub aus China; IV. Neue Anschauschauung des kleinstens
nordlichen Polarlebens. Mon.-ber. Akad. Wiss. Berlin, 1853, 505-533. pls. 1, 2.

Entz, G. Sr.

1883a. Beitriige zur Kenntnis der Infusorien. Zeitschr. wiss. Zool., 38, 167-189, pl. 8.

1883b. Die Flagellaten der Kochsalzteiche zu Torda und Szamosfalva. Term. Fuz., 7, 139-
168, pls. 3, 4.

1884. <A ndpolyi 6b6l esillészérés4zalékallatkéi. Orv. Term. Tud. Ertesité, 1884, 239-244.

1888. Tanulmadnyck a véglények kérebél. Studien tiber Protisten. Im Auftr. d. k. ungar.
Naturwiss. Gesellschaft verfasst. I. Theil, Entwicklung der Kenntnis der Pro-
tisten; Ein historisch-kritischer Ueberblick tibers. von Aladar Rozsahegyi (Buda-
pest, Verlag. Kgl. Ungar. Naturw. Ges.), xv + 464 pp.

520 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

1896. Protozoa. Jn Fauna regni Hungariae. R. Soe. sci. nat. Hung., Budapest, 6, 1-29,
1 map.

1897. Einleitung und allgemeine Betrachtungen tiber die Fauna des Balatonsees. In
**Resultate der wissenschaftlichen Erforsechung der Balatonsees.’’ Balatonsee
Comm. Geog. Ges., 2, i+ xxxix, 5 figs. in text.

Entz, G., Jr.

1901. Ejiniges iiber die Varieren der Infusioren. Math. Nat. Ber. Ungarn, 19 (1901) (dated
1904), 125-144, 10 figs. in text.

1902a. A Quarnero Peridinéai. Novén. Koézlem., 1, 83-96, pls. 1-6.

1902b. Adatok a Peridineék ismeretéhez. Math. Term. Ert., 20, 115-159, 62 figs. in text.

1904. Die Fauna der continentalen Kochsalzwisser. Math. nat. Ber. Ungarn, 19, 89-124,
2 figs. in text.

1905. Beitraige zur Kenntnis der Peridineen. Jbid., 20, 96-144, 66 figs. in text.

1907. A Peridineaék szervezetérél. All. K6z., 6, 11-30, 49, 50, pls. 2-4.

1909. Ueber die Organizationverhiltnisse einiger Peridineen. Math. nat. Ber. Ungarn, 25,
246-274, pls. 8-11.

1910. Egy édesvizi Gymnodiniumrél. All. K6z., 9, 157-164, pl. 3, 1 fig. in text.

1913. Ueber ein Siisswasser-Gymnodinium. Arch. Prot., 29, 399-406, pl. 13, 1 fig. in text.

Eyrertu, B.
1879. Schizophyten und Flagellaten. Supplement-Heft zu der Systematischen Naturge-
schichte der mikroskopischen Siisswasserbewohner (Braunschweig, Haering), 25 pp.,
2 pls.

Faurt-FREMIET, E.
1913a. Sur les ‘‘nematoeystes’’ de Polykrikos et de Campanella. C. R. Soc. Biol., Paris, 75,
366-368.
1913b. Sur les nematocystes et les trichoeystes de Polykrikos. Bull. Soe. Zool. France, 38,
289-290, 1 fig. in text.
1913c. Sur l’Erythropsis agilis R. Hertwig. C. R. Acad. Sci. Paris, 157, 1019-1022.
1914. Erythropsis agilis. Arch. Prot., 35, 24-45, pl. 1, 12 figs. in text.

FLORENTIN, R.
1899. Etudes sur la faune des mares salées de Lorraine. Ann. Sci. Nat. Zool., 10, 209-350,
pls. 8-10.

Fort, A.
1913. Primi studi per un’esplorazione limnobiologica dell’Oriente. Nuova Notar., 23, 23-36.

France, R.
1893. Zur Morphologie und Physiologie der Stigmata der Mastigophoren. Zeitschr. wiss.
Zool., 56, 138-164, pl. 8.
1897. Protozoa. Jn ‘‘Resultate der wissenschaftlichen Erforschung der Balatonsees.’’
Balatonsee Comm. geog. Ges., 2, 1-64, 41 figs. in text.
1908. Die Lichtsinnesorgane der Algen; Studien zum Ausbau der vegetabilen Reizphysi-
ologie I. (Stuttgart, Kosmos), 80 pp., 1 pl., 14 figs. in text.

Francs, R., AMMANN, H., and Lreuzse, M.
1912. Plankton-bestimmungsbuch (Miinchen, Huber), 68 pp., 50 figs. in text.

FRESENIuS, G.
1865. Die Infusorien des Seewasseraquariums. Zool. Gart.,,1865, 82-89, 1 pl.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 521

FROMENTEL, E.
1874. Etudes sur les Microzoaires ou Infusoires proprement dits comprenant de nouvelles
recherches sur leur organisation, leur classification et la deseription des especes
nouvelles ou peu connues (Paris, Masson), viii + 364 pp., pls. 1-30.

Gietrour, E. H.
1870. la fosforescenza del mare note pelagiche ed osservazioni fatte durante un viaggio di
cireumnavigazione 1865-68, colla deserizione di due nuove Noctiluche. Atti Ace.
Torino, 5, 485-505.

Goueu, L. H.
1904. Plankton collected at Irish light stations. Ireland Sci. Invest. Fish., 1904, 1-55.
1907. Report of the plankton of the English Channel in 1904 and 1905. North Sea Fisheries
Investigation Committee, 2d Rep., 1904-5, pt. 1, pp. 165-258, pls. 1-4.

Gourret, P.
1883. Sur les Péridiniens du Golfe de Marseille. Ann. Mus. Hist. Nat. de Marseilles, Zool.,
1, 1-144, pls. 1-4.

Gourret, P., and Rosssr, P.
1886. Les Protozoaires du vieux-port de Marseille. Arch. Zool. exp. et gen., Ser. 2, 4, 443-
534, pls. 28-35.

GRIESSMAN, K.
1913. Ueber marine Flagellaten. Arch. Prot., 32, 1-78, 24 figs. in text.

GrirFitH, J. W., BerKeLry, M. J., and Jones, T. R.
1883. The micrographie dictionary (London, Van Voorst), ed. 4, xlvi + 829 pp. 53. pils.,
818 figs. in text.

GROSVENOR, G. H.
1903. On the nematocysts of aeolids. Proce. Roy. Soc., London, 72, 462-487, 13 figs. in text.

Ginruer. H. ;
1911. Fortschritte in der Mikrobiologie und mikroskopischen. Technik (Stuttgart,
Franckh’sche Verlags.), 1, 1-64.

Guyer, O.
1910. Beitriige zur Biologie des Greifensees mit besonderer Beriicksichtigung der Saison-
variation von Ceratiwm hirwndinella. Arch. Hydrob., 6, 281-270, 363-441, pls.
6-11, 27 figs. in text.

HArcKEL, E.
1873a. Zur Morphologie der Infusorien. Jena. Zeitschr. Med. Naturw., 7, 516-561, pls. 27-28.
1873b. Ueber einige neue pelagische Infusorien. Jbid., 7, 561-567, pls. 27, 28.

Hampureer, C.
1911. Studien iiber Euglena ehrenbergii insbesondere iiber die Korperhiille. SB Akad.
Wiss. Heidelberg math.-nat. K1., 1911, 1-22, pl. 1.

Harroa, M.
1906. The Protozoa. Cambr. Nat. Hist., 1, 1-162, 62 figs. in text.

HARTMANN, M.
1911. Die Konstitution der Protistenkerne und ihre Bedeutung fiir die Zellenlehre (Jena,
Fischer), vi + 54 pp., 13 figs. in text.

522 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

HENSEN, V.
1891. Die Plankton-Expedition und Haeckel’s Darwinismus, tiber einige Aufgaben und
Ziele der beschreibenden Naturwissenschaften (Kiel und Leipzig, Lipsius und
Tischer), 87 pp., 2 pls.

HERDMAN, W.

191la. Dinoflagellates and diatoms on the beach. Nature (London), 86, 554.

1911b. On the occurrence of Amphidinium operculatum. Clap. and Lach., in vast quantity,
at Port Erin (Isle of Man). Jour. Linn. Soe. London, Zool., 32, 71-75, pl. 8.

1911c. The Marine Biological Station at Port Erin, being the twenty-fifth annual report of
the Liverpool Marine Biology Committee. Trans. Liverpool Biol. Soe., 25, 1-59,
28 figs. in text.

1912. Idem. Ibid., 26, 1-89, 21 figs. in text.

1913. Idem. Ibid., 27, 1-70, 22 figs. in text.

Herrtwie, R.
1884. Erythropsis agilis: Kine neue Protozoa. Morph. Jahrb., 10, 204-212, pl. 6.
1885. Ist Erythropsis agilis eine losgerissene Spastostyla sertulariarum? Zool. Anz., 8, 108-
112.

Huitrevpt-Kass, H.
1900. Die limnetischen Peridineen in Norwegischen Binnenseen. Vid. Skrif., math. nat.
Kl. Christiania, 1900, 1-7, pl. 1.

Hutton, F. W.
1904. Index faunae Novae Zealandiae (London, Dulau), viii + 372 pp.

Imuor, O. E.
1892. Die Zusammensetzung der pelagischen Fauna der Siisswasserbecken. Biol. Centrbl.,
12, 171-183, 200-205.

ISHIKAWA, C.
1891. Vorlaufige Mitteilungen tiber die Konjugationerscheinungen bein den Noctiluceen.
Zool. Anz., 1891, 12-14. .
1894. Studies of reproductive elements. II. Noctiluca miliaris Sur; its division and spore
formation. Jour. College Sci. Imp. Univ. Japan, 6, 397-334, pls. 11-14.
1899. Further observations on the nuclear division of Noctiluca. Ibid., 12, 243-262, pl. 19.

Twanorr, L.
1900. Ueber neue Arten von Algen und Flagellaten, welche an der biologischen Station zu
Bologoye gefunden worden sind. Bull. Soc. Imp. Natural, Moscow, 14, 423-449,
pls. 12, 13.

JoLLos, V.
1900. Dinoflagellatenstudien. Arch. Prot., 19, 178-206, pls. 7-10.

JORGENSEN, E.

1899. Protophyten und Protozoen im Plankton aus der norwegischen Westktiste. Bergens
Mus. Aarbog., No. 6, pp. 1-112, pls. 1-5.

1910a. Report of Prof. Dr. E. Jérgensen, of the Cathedral School of Bergen, Norway.
Carnegie Inst. Wash., Yearbook, Dept. Marine Biol., 9, 146-148.

1910b. Reports on investigations and projects. Jbid., 9, 146-148.

1912. Bericht iiber die von der schwedischen hydrographisch-biologischen Kommission in
der schwedischen Gewissern an den Jahren 1909-1910, eingesammelten Plankton-
proben. Svenska Hydrog.-Biol. Komm., 4, 1-20. ~

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 523

KARSTEN, G.
1905. Das Phytoplankton des antarktischen Meeren nach dem Material der deutschen Tiefsee
Expedition. Wiss. Ergeb. deutsch. Tiefsee Exped., 2, 1-219, pls. 1-34.
1907. Das indische Phytoplankton. Jbid., 2, 221-548, pls. 35-54, 4 figs. in text.

KerysseLirz, G.
1908a. Die Entwicklung von Myzobolus pfeifferi Th. Arch. Prot., 11, 252-275, pls. 13, 14,
7 figs. in text.
1908b. Studien iiber Protozoen. Aus dem Nachlass von Fritz Schaudinn. Jbid., 11, 334-350,
pls. 19-21.

Kueps, G.

1883. Ueber die Organisation einiger Flagellaten Gruppen und ihre Bezichungen zu Algen
und Infusoria. Untersuch. bot. Inst., Tiibingen, 1, 233-362, pls. 2, 3.

1884. Ein kleiner Beitrag zur Kenntnis der Peridineen. Bot. Zeitschr., 42, 721-733, 737-745,
pl. 10.

1892. Flagellaten-Studien. I. Zeitschr. wiss. Zool., 55, 265-351, pls. 113-116.

1912. Ueber Flagellaten und algenahnliche Peridineen. Verh. nat. Ver. Heidelberg, 11,
367-451, pl. 10, 15 figs. in text.

KueErBer, D.
1911. Die Tierwelt des Moorgebietes von Jungholz in siidlichen Schwarzwald. Arch. Naturg.,
77, supp. 3, pp. 1-155, 20 figs. in text.

Koro, C. A.

1898. Plankton studies. II. On Pleodorina illinoisensis, a new species from the plankton of
the Illinois River. Bull. Illinois State Lab. Nat. Hist., 5, 273-293, pls. 36, 37.

1899. Plankton studies. III. On Platydorina, a new genus of the family Volvocidae, from
the plankton of the Illinois River. Jbid., 5, 419-440, pl. 38.

1907a. New species of dinoflagellates. Bull. Mus. Comp. Zool. Harvard, 50, 163-207, pls.
1-17.

1907b. The structure and systematic position of Polykrikos Biitsch. Zool. Anz., 31, 291-293,
1 fig. in text.

1907c. Dinoflagellata of the San Diego region. III. Description of new species. Univ. Calif.
Publ. Zool., 3, 299-340, pls. 22-33.

1908. Exuviation, autotomy and regeneration in Ceratium. Tbid., 4, 845-386, 33 figs. in text.

1909a. On Peridinium steini Jorgensen, with a note on the nomenclature of the skeleton of
the Peridinidae. Arch. Prot., 16, 25-47, pl. 2.

1909b. The morphology of the skeleton of Podolumpas. Ibid., 16, 48-61, pl. 3.

1909ce. Mutations in Ceratium. Bull. Mus. Comp. Zool. Harvard, 52, 211-257, pls. 1-4, 5

; figs. in text.

1910a. The faunal relations of the Dinoflagellata of the San Diego region. Proe. 7th Intern.
Zool. Cong. Boston, 1910, 922-927.

1910b. Significance of certain forms of asymmetry of the dinoflagellates. Jbid., 1910, 928-931.

1911. Dinoflagellata of the San Diego region. IV. The genus Gonyaulax, with notes on its
skeletal morphology and a discussion of its generic and specific characters. Univ.
Calif. Publ. Zool., 8, 187-300, pls. 9-19, 5 figs. in text.

1919. The morphological interpretation of the structure of Noctiluca, and its bearings on
the status of the Cystoflagellata (Haeckel). Jbid., 19, 317-334, pl. 18, 2 figs. in text.

Koro, C. A., and Riepren, E. J.
1912. A peculiar form of schizogony in Gonyaulax. Bull. Mus. Comp. Zool. Harvard, 54,
335-348, pls. 1-2, 2 figs. in text.

524 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Koroip, C. A., and Swezy, O.
1915. Mitosis and multiple fission in trichomonad flagellates. Proce. Amer. Acad. Arts. Sci.,
51, 289-378, pls. 1-8, 7 figs. in text.
1917. On the orientation of Erythropsis. Univ. Calif. Publ. Zool., 18, 89-101, 12 figs. in text.

Koukwirz, R.
1911. Zur Biologie der Talsperren. Mitt. Kgl. Priifung. Wasserversorg. Abwiss., 15, 268-
411, pls. 5-11, 16 figs. in text.
1912. Das Plankton des Rheinstroms vom seinen Quellen bis zur Miindung. Ber. deutsch.
Bot. Ges., 30, 205-226.

KUNSTLER, J.
1886. Les ‘‘yeux’’ des infusoires flagelliferes. Jour. Microg., Paris, 11, 493-496.

Kuster, E.
1908. Hine kultivierbar Peridinee. Arch. Prot., 11, 351-362, 4 figs. in text.

LAACKMANN, H.

1906. Ungeschlechtliche und geschlechtliche Fortpflanzung der Tintinnen. Wiss. Meeres-
unters. Abt. Kiel, 10, 15-38, pls. 1-3.

LAGERHEIM, G.
1900. Beitrage zur Flora der Biren-Insl. Vegetablischen Sitisswasser-Plankton aus der
Biren-Insel (Beeren Eiland). Bihang. Kgl. Svenska Vet.-Akad., 26, No. 11, pp.
1-25, 2 figs. in text.

LAMARCE, J. B.

1816. Histoire naturelle des animaux sans vertébres, présentant les caractéres généraux et
particuliers de ce animaux, leur distribution, leurs classes, leurs familles, leurs
genres, et la citation des principales espéces qui s’y rapportent (Paris, Verdiere),
2, 568 pp.

Lane, A.

1901. Lehrbuch der vergleichenden Anatomie der wirbellosen Thiere (Jena, Fischer), 1,
1-311, 259 figs. in text.

LANKESTER, E. R.
1885. Protozoa. In ‘‘Eneye. Brit.’’ (ed. 10, London), 19, 830-866, 26 figs. in text.

LAUTERBORN, R.

18940. Ueber die Winterfauna einiger Gewiisser der Oberrheinebene, mit Beschreibungen
neuer Protozoen. Biol. Centrbl., 14, 390-398.

1294. Die pelagischen Protozoen und Rotatorien Helgolands. Wiss. Meeresunters. Abt.
Helgoland, 1, 207-213, 2 figs. in text.

1895. Kern- und Zelltheilung von Ceratium hirundinella, O. F. M. Zeitschr. wiss. Zool.,
59, 167-190, pls. 12, 13.

1898. Protozoen-Studien. IV. Flagellaten aus dem Gebiete des Oberrheins. Jbid., 65, 369-
391, pls. 17, 18.

1910a. Bericht iiber die Ergebnisse der 8. biologischen Untersuchung des Oberrheins auf der
Strecke Basel-Mains (vom 4. bis. 16. Juli, 1908). Arb. kais. Gesund., 36, 239-259.

1910b. Die Vegetation des Oberrheins. Verh. Nat. Med. Ver. Heidelberg, N. F., 10, 450-502.
2 figs. in text.

1913. Siisswasserfauna. Handwort. Naturwiss., 9, 861-920, 27 figs. in text.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 525

Lesour, M. V.

1917a

1917b

. The microplankton of Plymouth Sound from the region beyond the breakwater. Jour.
Mar. Biol. Assoc., 11, 132-182, 9 figs. in text.

. The Peridiniales of Plymouth Sound from the region beyond the breakwater. Jbid.,
11, 183-200, 14 figs. in text.

LEMMERMANN, E.

1896a
1896b

18994

1899b
1900.

1901la

19016
1902.

1903.

1905a
1905b

. Zur Algenfiora des Riesengebirges. Forsch. Biol. Stat. Plién, 4, 88-133, 25 figs. in text.
. Zweiter Beitrag zur Algenflora des Ploéner Seengebietes. Jbid., 4, 134-188, 12 figs.
in text.
. Ergebnisse einer Reise nach dem Pacific. Planktonalgen. Abh. Naturw. Ver. Bremen,
16, 313-398, pls. 1-3.
. Das Phytoplankton sichsischer Teiche. Forsch. Biol. Stat. Plén., 7, 96-135, pls. 1, 2.
‘Beitrige zur Kenntnis der Planktonalgen VIII. Peridiniales aquae dulcis et sub-
marinae. Hedwigia, 39, 115-121.
_ Algenflora eines Moortiimpels bei Plén. Forsch. Biol. Stat. Plon., 8, 64-73, 6 figs. in
text.
. Das Phytoplankton des Meeres. Abh. Naturw. Ver., Bremen, 17, 341-418.
Bericht der Commission fiir die Flora von Deutschland. VIII. Peridiniales. Ber.
deutsch. Bot. Ges., 20, 257-263.
Beitrige zur Kenntnis der Planktonalgen. XV. Das Phytoplankton einiger Pléner
Seen. Forsch. Biol. Stat. Plon., 10, 116-171, 7 figs. in text.
. Das Phytoplankton des Meeres.. Beihefte Bot. Centrbl. Jena, 19, 1-74.
. Beitrige zur Kenntnis der Planktonalgen. XX. Phytoplankton aus Schlesien. Forsch.
Biol. Stat. Plon., 12, 154-163, pl. 4.

1905c. Idem. XXI. Das Phytoplankton siichsischer Teiche. Jbid., 12, 164-168.

1906.

1908.
1910.

Ueber das Vorkommen von Sitisswasserformen im Phytoplankton des Meeres. Arch.
Hydrob., 1, 409-427.

Algologische Beitrige. IJbid., 4, 165-192, pl. 5.

III. Klasse. Peridiniales. Jn Algen in Kryptogamenflora der Mark Brandenburg und
angrenzender Gebiete, 3, 563-712, 369 figs. in text.

LeucKkart, R.

1861.

Bericht iiber die wissenschaftlichen Leistungen in der Naturgeschichte der niederen
Thiere wahrend des Jahres 1859. Arch. Naturg., 2, 103-264.

LevANnper, K. M.

1892.

Verzeichniss der wiihrend des Sommers 1891 bei Rostock beobachteten Protozoen.
Arch. Ver. Freunde Nat. Mecklenburg, 46, 113-116.

1894a. Materialien zur Kenntnis der Wasserfauna in der Umgebung von Helsingfors beson-

1894b

derer Beriicksichtigung der Meeresfauna. Acta Soc., Fauna, Flora Fenn., 12,
No. 2, 1-115, pls. 1-3.

. Liste iiber im finnischen Meerbusen in der Umgebung von Helsingfors beobachtete
Protozoen. Zool. Anz., 17, 209-212.

1900a. Zur Kenntnis des Lebens in den stehenden Kleingewiissern auf den Skireninseln.

1900b

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526 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

LIEPETANZ, E.

1905. Die parasitischen Protozoen des Wiederkauermagens. Inaug. Diss. Bern, 84 pp.
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Murray, JOHN
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OKAMoURA, K.
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OKEN, L.

1815. Lehrbuch der Naturgeschichte 3. Theil. Lehrbuch der Zoologie (Jena, Schmid),
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OLTMANNS, F.
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1906: Catalogue des espéces de plantes et d’animaux observées dans le plankton recueilli
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1913. De Danske farvandes Plankton. Vid. Skrif., Math.-nat., 9, 113-478, 75 tables, 9 figs.
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OsTENFLED, C. H., and Pauussn, O.
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1883. Recent researches on the Cilioflagellata. Quart. Jour. Mier. Sei., 22, 416-420.

Parker, T. J.. and HASweELu, W. A.
1897. A text book of zoology (New York, Macmillan), 1, xxxv + 779 pp., 663 figs. in text.

PascHer, A.

1916. Ueber eine neue Amoeba-Dinamocbe (varians) mit dinoflagellatenartigen Schwiirmen.
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PAuLsEn, O.
1907. The Peridiniales of the Danish waters. Medd. Komm. f. Havunderség., Série Plankton,
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PAVILLARD, J.
1905. Recherches sur la flore pélagique (phytoplankton) de l’Etang de Thau. Mem. Univ.
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1888. Contributions a 1’étude des Dinoflagellés. Recherches sur le Ceratiwm macroceros
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1882. Sur 1’évolution des Péridiniens et les particularites d’organisation qui les rapprochent
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18920. Sur la flore pélagique de Naalsoefjord. C. R. Acad. Sci. Paris, 114, 86, 87.

1892b. Sur la faune pélagique de Dyrefjord (Islande). J/bid., 114, 191-192.

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1919. Binary fission in Collodicyton triciliatum Carter. Uniy. Calif. Publ. Zool., 19, 201-274,
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Riweway, R.
1912. Color standards and color nomenclature (Washington, Ridgway), iv + 44 pp., 53 pls.

Rigss, F.

1842. Beitrage zur Fauna der Infusorien mit dem beigefiigten Ehrenberg’schen Systeme.
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1878. Recherches sur la reproduction gemmipare et fissipare des Noctiluques (Noctiluca
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ROSENTHAL, C.
1914. Das Kammerplankton der Spree bei Berlin. Intern. Revue Hydrob. Hydrog., 6, Biol.
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SAVILLE-KENT, W.
1880-82. A manual of the Infusoria (London, Bogue), 1, 1-472; 2, 473-913; 3, pls. 1-50.

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1900. Phaeocystis globosa nov. spec., einigen Betrachtungén tiber die Phylogenie niederer,
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1889. Beitrige zur Kenntnis der holotrichen Ciliaten. Bibl. Zool., 5, 1-77, pls. 1-7.
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1901. Preliminary report of the botanical results of the Danish Expedition to Siam (1899-
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ScH6nIcHEN, W., and KaLBeruan, A.
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SENN, G.
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1898a. Das Heleoplankton. Zool. Anz., 21, 24-32.
1898b. Ueber einige interessante Funde im Plankton siichsischen Fischteiche. Biol. Centrbl.,

18, 714-718, 5 figs. in text.
1898c. Untersuchungen tiber das Plankton der Teichgewisser, Forsch. Biol. Stat. Plon., 6,
89-139, pl. 4, 3 figs. in text.

534 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

1899. Ueber Pseudopodienbildung bei einem Dinoflagellaten. Biol. Centrbl., 19, 141-144, 9
figs. in text.

1903. Zur Kenntnis der niederen Flora und Fauna holsteinischer Moorsiimpfe.
Biol. Stat. Plon., 10, 223-289, pl. 2, 8 figs. in text.

1906. Ueber Periodizitat, Variation und Verbreitung verschiedner Planktonwesen in siid-
lichen Meeren. Arch. Hydrob., 1, 498-575, 23 figs. in text.

Forsch.

ZEDERBAUER, E.

1904. Gesehlechthehe und ungeschlechtliche Fortpflanzung von Ceratium hirundinella. Ber.
deutsch. bot. Ges., 22, 1-8, pl. 1.

ZENKER, A.

1912. Algenflora des ostfalischen Berg- und Hiigellandes und der Nordspitze des Harzes.
Inaug. Diss., Gottingen, 153 pp.

ZSCHOKKE, F.

1900. Die Tierwelt der Hochgebirgsseen. Schr. Naturf. Ges. Danzig, 37, vii + 400, 4 maps,
pls. 1-8.

ZUMSTEIN, H.

1899. Yur Morphologie und Physiologie der Euglena gracilis Klebs. Jahrb. wiss. Bot., 34,
419-469, pl. 6.

ZYKOFF, W.

1902. Die Protozoa des Potamoplanktons der Wolga bei Saratow. Zool. Anz., 25, 177-180.

“¢ Acinetea,’’ 486.
Acknowledgments, vii.

Amphidinium, 124; organology,
125; coloring, 128; distribu-
tion, 128; subgenera of, 131;
key to species, 131.

aculeatum, 132.
asymmetricum, 133.
corpulentum, 134.
erassum, 135.
cucurbita, 136.
cucurbitella, 137.
dentatum, 138.
discoidalis, 139.
emarginatum, 140.
fastigium, 140.
galbanum, 141.
globosum, 142.
herdmani, 143.
klebsi, 144.
laeustre, 145.
lanceolatum, 146.
longum, 146.
opereulatum, 147.
var. discoidalis, 139.
var. emarginata, 140.
ovoideum, 148,
pacificum, 149.
rotundatum, 150,
scissum, 150.
steini, 152.
suleatum, 153.
truncatum, 154.
turbo, 155.
vasculum, 156.

Amphidinium, subgen., 131.

Arenaciphilous microfauna and

flora, 95.
Bergh, R. S., 102.
Binary fission, 19, 69.
Blastodinium erassum, trophocyte

in, 21.

Ceratium hirundinella, binary fis-
sion in, 19.
tripos, binary fission, 19.

Chromatophores, 47.

INDEX

Chytriodinium, 229.
Claparéde and Lachmann, 101,

Classification of the Dinoflagellata,
system of, 106.

Cochlodinium, 342; organology,
342; color, 344; distribution,
345; historical discussion, 348;
subgenera of, 348; key to
species, 350.

archimedes, 351.
atromaculatum, 352.
augustum, 354.
eatenatum, 355.
cavatum, 356.
cereum, 357.
citron, 358.
clarissimum, 359.
conspiratum, 361.
constrictum, 362.
convolutum, 363.
distortum, 364.
elongatum, 366.
faurei, 366.
geminatum, 368.
helix, 370.
lebourae, 371.
longum, 315.
miniatum, 372.
pellucidum, 374.
pirum, 374.
pulchellum, 376.
radiatum, 377.
rosaceum, 379.
schuetti, 380.
scintillans, 381.
strangulatum, 382.
turbineum, 383.
vinctum, 384.
virescens, 386.
volutum, 387.

Cochlodinium, subgen., 348.
Collections and material, 4.
Coloration, 37.

Colors, system of nomenclature, 6.
Comparative organology, 55.
Cytoplasmie differentiation, 36.

Cytostome, 50.

Derivation, 82.

Diniferidae, key to tribes, 108.
Diniferidea, 108.

Dinoflagellata, brief outline of, 8;

classification, 106; key ‘to
orders, 108.

Diplodinium, 232.

Dissodinium, 232.

Distribution, 94;
local, 99.

seasonal, 97;

Ehrenberg, C. G., 101.

Encystment, 72.

Erythropsis, 477; description, 478;
historical discussion, 481; prod
of, 12; species and distribu-
tion, 485; key to species, 487.

agilis, 487,
cochlea, 489.
cornuta, 491.
extrudens, 494.
hertwigi, 487.
hispida, 499.
labrum, 501.
minor, 503.
Pavillardi, 505.
richardi, 508.
scarlatina, 510.
Erythropsis, subgen., 487.

Evolution of dinoflagellates, struc-
tural, 89; nutrition and, 91.

Evolutionary development, 77.

Form and size of flagellates, 8.

Furrows of the body, 13. See also
Girdle.

Girdle, structural feature, 14.

Glenodinium roseolum, 250.
uberrimum, 264.

Glyphidium marinum, 119.

Glyphodinium, subgen., 349.

Gymnodiniidae, 120; key to genera,
121.

Gymnodinioidae, 109; discussion,
109; key to families, 111.

536 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Gymnodinium, 158; organology,
159; coloring, 162; distribu-
tion, 166; historical discussion,
170; subgenera of, 174; species
of uncertain status in, 175;
key to species, 176.

abbreviatum, 180.
achromaticum, 181.
aeruginosum, 183.
agile, 184.
amphora, 185.
archimedes, 351.
attenuatum, 186.
auratum, 187.
aureum, 188.
bicaudatum, 189.
biciliatum, 190.
picorne, 191.
pifurcatum, 192.
bogoriense, 193.
canus, 194.
earinatum, 195.
cinctum, 196.
coeruleum, 197.
eonicum, 198.
constrictum, 362.
corpusculum, 200.
costatum, 200.
crassum, 295.
eucumis, 202.
diploconus, 203.
dissimile, 204.
dogieli, 205.
doma, 206.
filum, 207.
fissum, 301.
flavum, *208.
fucorum, 305.
fulgens, 209.
fuseum, 210.
fusus, 212, 299.
geminatum, 369.
gleba, 213.
gracile, 214, 297.
var. exiguum, 216.
var. sphaerica, 259.
grammaticum, 217.
hamulus, 218.
helix, 371, 380.
helveticum, 219.
herbaecum, 220.
heterostriatum, 221.
hyalinum, 312.
incisum, 223.
jinerme, 224.
lachmanni, 224.
lineatum, 225.
lineopunicum, 226.
lira, 227.
lohmanni, 229.
lunula, 229.
marinum, 232.

minimum, 266.
mirabile, 234.

rufescens, 264.

var. rubescens, 264.

monadicum, 234
monas, 235.
multilineatum, 235.
multistriatum, 236.
musei, 237.
ovatum, 323.
ovulum, 238.
ovum, 325.
pachydermatum, 239.
palustre, 241, 272.
parvulum, 325.
paradoxum, 242.
pirum, 374.

vorticelli, 269.

wilezeki, 270.

zachariasi, 271.
Gymnodinium, subgen., 174.

Gyrodinium, 273; organology, 273;
color of cytoplasm, 276; dis-
tribution, 278; historical dis-
cussion, 279; subgenera of,
281; key to species, 282.

acutum, 285.
biconicum, 286.
britannia, 287.
capsulatum, 288.
caudatum, 289.
concentricum, 290.
contortum, 291.

polyphemus var. magna, 417. corallinum, 292.

var. nigrum, 418.
var. roseum, 461.
pseudonoctiluca, 243.
punctatum, 244.

var. grammaticum, 217.
puniceum, 245.
pusillum, 330.
pyrocystis, 246.
radiatum, 246.
ravenescens, 247.
rete, 248.
rhomboides, 249.
roseolum, 250.
roseum, 229.
rotundatum, 251.
rubricauda, 251.
rubrum, 253.
rufescens, 264.
scopulosum, 255.
simplex, 256.
situla, 257.
sphaericum, 258.
spirale, 334.

var. acuta, 285.

var. cornutum, 293.

var. D., 301.

var. mitra, 319.

var. obtusa, 320.

var. pepo, 326.

var. nobilis, 334.

var. striatum, 334.
strangulatum, 383.
sulcatum, 259.
tenuissimum, 260.
teredo, 391, 394.
tintinnicola, 261.
translucens, 262.
triangularis, 263.
uberrimum, 264.
varians, 265.
vestifici, 266.
violescens, 267.
viride, 268, 304.
viridis, 198.

cornutum, 293.
erassum, 294.
culeus, 296.
cuneatum, 297.
dorsum, 298.
falcatum, 299.
fissum, 300.
flavescens, 302.
flavidum, 303.
foliaceum, 304.
fucorum, 305; binary fission in,
19.
fulvum, 306.
fusiforme, 307.
glaucum, 308.
grave, 309.
herbaceum, 310.
hyalinum, 311.
intortum, 312.
lachryma, 314.
longum, 314.
maculatum, 315.
melo, 317.
mitra, 318.
obtusum, 319.
ochraceum, 321.
ovatum, 322.
ovoideum, 323.
ovum, 324.
parvulum, 325.
pepo, 326.
pingue, 327.
postmaculatum, 328.
pusillum, 329.
rubricaudatum, 330.
schuetti, 331.
spirale, 332.
spumantia, 334.
submarinum, 335.
truncatum, 337.
truncus, 338.
virgatum, 339.
viridescens, 340.

Gyrodinium, subgen., 282.

KOFOID AND SWEZY: UNARMORED DINOFLAGELLATA 537

Hemidinium, 121; key to species,
122.
nasutum, 122.
ochraceum, 124.
Heteraulacus adriaticum, 182.
fuscus, 210.
Heteroaulax adriatica, 182.
Historical discussion, 100.
Holozoie nutrition, evidences of,
148.

Laevigella, subgen., 282.

Lens of ocelli, 25.

Life cycles, 62; effects of parasit-
ism on, 66.

Lineadinium, subgen., 175.

Luminescence, 52.

mammaria scintillans, 407, 412.
“Mare Sporco,’’ 1.

‘¢Medusa Marina,’’ 406, 407, 412.
Medusa scintillans, 406, 407, 412.
Material, and collections, 4.
Melanin, 38.

Melanosome of ocelli, 25.
Melodinium uberrimum, 264.

Metazoa, relations of dinoflagel-
lates to, 93.

Methods, 6.

Morphology, general, 7; size and
form, 8; motor organelles, 11;
furrows and torsions of the
body, 13; nuclei, 18; pusules,
22: ocelli, 24; nematocysts,
29; eytoplasmie differentiation,
36; coloration, 37; surface dif-
ferentiation, 41.

Motor organelles, 11.
Miiller, O. F., 100.
Multiple fission, 89.

Nematoeysts, structural feature,
29, 59; structure of, 30; orien-
tation, 30; development, 34;
mature, number of, 34.

Nematodinium, 421; comparisons,
421; key to species, 422.

armatum, 422.
partitum, 425.
torpedo, 426

Nereis noctiluca, 406.

Nocetiluea, 406.

banskii, var., 407, 412.
miliaris, 407.
omogenea, 407, 412.
pacifica, 407, 412.
punctata, 407, 412.
scintillans, 407, 413.

‘¢Noctilueca marina,’’ 407, 412.

Noctilucidae, 403; historical dis-
cussion, 403; key to genera,
403.

Nuelear division, 18.

Nuclei, structural feature, 18.

Nutrition, 45; holozoic, 48; and
evolution, 91; two types of,
saprophytic, parasitic, 92.

Oeelli, structural feature, 56; lens,
25; melanosome, 25; orienta-
tion of, 28.

Outline, brief, of dinoflagellata, 8.

Oxyrrhis, 116.

marina, 117. ’

Pachydinium, subgen., 175.

Parasitie dinoflagellates, 12.

Parasitic nutrition, 92.

Parasitism, effects of, on life cycle,
66.

Pavillardia, 403; historical discus-

sion, 404.
tentaculifera, 404.
Peridinium adriaticum, 183.
brochi, 183.
corpusculum, 200.
fuscum, 212.
inerme, 224.
roseolum, 250.

Phosphorescence, 209.

Physiology, 43.

Photochrysis, 90.

Physematiwm atlanticum, 406.

Pigment, motility of, 39.

Polydinium, subgen., 349.

Polykrikidae, 395.

Polykrikos, 395; organology, 395;
distribution, 396; historical
discussion, 397; key to species,
398.

auricularia, 402.
kofoidi, 398.
sechwartzi, 400.

Polyopsidella, subgen., 487.

Pouchet, G., 102.

Pouchetia, 429; organology, 429;
color of cytoplasm, 432; dis-
tribution, 434; historical dis-
cussion, 435; subgenera of,
436; key to species, 437.

alba, 438.
armata, 421.
atra, 439.
cochlea, 489.
compacta, 441.

contorta, 441.

cornuta, 493.

fusus, 443.

juno, 444.

maculata, 446.

maxima, 448.

nigra, 418, 446.

panamensis, 450.

parva, 451.

polyphemus, 453.

poucheti, 455.

purpurata, 457.

purpurescens, 458.

rosea, 460.

rubescens, 463.

schuetti, 465.

striata, 467.

subnigra, 468.

violescens, 469.

voracis, 471.
Pouchetia, subgen., 436.
Pouchetiella, subgen., 436.
Pouchetiidae, 413; description,

413; key to genera, 414.
Prod, of Erythropsis, 12.
Proterythropsis, 474; discussion,
474.
crassicaudata, 475.

Prorocentrum ovoideum, 149.
Protodinifer, 112; key to species,
112.
marinum, 115.
tentaculatum, 112.
Protodiniferidae, 111; key to
genera, 112.
Protodinium simplex, 256.
Protopsis, 415; key to species, 416.
neapolitana, 416.
nigra, 418.
ochrea, 420.
Pseudopod formation, 13.

Pusules, structural feature, 22, 57;
function, 23.

Pyrocystis lunula, 232.

Reactions to stimuli, 50.
“‘Red water,’’ 44.

Relationships, 78; to the Metazoa,
93.

Rhabdosomes, structural feature,
37.

Ridgway’s system of nomenclature
of colors, 6.

Rotundinium, subgen., 131.

Saprophytie nutrition, 92.
Sechiitt, F., 1038.
Size and form of flagellates, 8.

5388 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA

Slabberia, 406, 407.
Spastostyla sertulariarum, 487.
Spirodinium, 279.
concentricum, 290.
cornutum, 293.
crassum, 294.
equi, 279.
fusus, 307.
grave, 310.
hyalinum, 311.
lachryma, 314.
opimum, 291.
pusillum, 329.

spirale, 333.
var. acutum, 285, 288.
var. mitra, 319.
var. obtusum, 319.
var. pepo, 326.
var. pingue, 327.

Stein, F., 101.

Stigma, of fresh-water dinoflagel-
lates, 57, 88.

Suleus (furrow), structural feature,
14; description, 16; function,
IW

Structural evolution, 89.

Surface differentiation, 41.

Torodinium, 389; description, 389;
comparisons, 390; historical
discussion, 390; key to species,
390.

robustum, 391.
teredo, 393.

Torsions of the body, 13.
Trophoeyte, in Blastodinium cras-
sum, 21.

Wysotzkia, 80.

¢. oy ro
By

.

EXPLANATION OF PLATES

All figures are made with the aid of a camera lucida from living material by the authors and
colored by Miss Anna Hamilton, unless otherwise stated.

PLATE 1

Fig. 1. Amphidinium asymmetricum sp. nov. Camera drawing by Miss Inez Smith. Ven-
tral view. Note the single large, ramifying chromatophore obscuring the centrally located
nucleus. X 1323.

Fig. 2. Gymnodinium lineatum sp. nov. Ventral view. The surface striae show the un-
usual obliquity characteristic of the species. Note the branching pusule and the aggregated
pigment at the antapex. X 626.

Fig. 3. Gyrodinium truncatum sp. nov. Three food bodies are present. _Encystment is
apparently a quiet period aiding digestion. > 1102.

Fig. 4. Amphidinium galbanum sp. nov. Ventral view. The surface is lightly furrowed
and immediately beneath it are the green, leaflike chromatophores. The nucleus is posteriorly
located. 1102.

Fig. 5. Gymnodinium aureum sp. noy. Dextroventral view. Note the striae of broken
lines and two small, colored spherules, probably food remnants. > 600.

Fig. 6. Amphidinium cucurbitella sp. nov. Dextroventral view. Surface deeply furrowed.
Two large food masses present, one recently ingested, surrounded by a water vacuole which has
disappeared in the second food body. > 626.

Fig. 7. Gymnodinium scopulosum sp. nov. Sinistroventral view. An eneysted individual
with cytoplasm unusually free from the products of metabolism. The size of the cyst indicates
an advaneed stage of encystment. > 1102.

Fig. 8. Cochlodiniwm schuetti sp. nov. Sinistroventral view. Note the single large food
body, the minute oil droplets in periphery, and the two pusules merged into one. X 1102.

Fig. 9. Amphidinium cucurbita sp. nov. Ventral view. Compare the complex cytoplasmic
structure with the simpler condition in Amphidinium galbanum (fig. 4). The nucleus is the
reniform body dorsad to the posterior pusule. Surface deeply striate. 626.

Fig. 10. Gymnodinium ravenescens sp. nov. Ventral view. Two food bodies present with
chromatophores. Note the similarity of chromatophores with those of Amphidinium corpulentum
Gics i) << t02:

Fig. 11. Amphidinium corpulentum sp. nov. Ventral view. Note the presence here also
of food bodies or the products of metabolism and chromatophores, indicating both holozoie and
holophytic nutrition. The nucleus is the long, ellipsoidal body on the right side. X 1323.

Fig. 12. Gymnodinium situla sp. noy. Ventral view. Note the colored food bodies, vacuoles
and spherules, products of metabolism. Nucleus is posteriorly located. > 1102.

[540]

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA, VOLUME 6& [ KOFOID—SWEZY] PLATE 1

j a)

a ae

sl -*
i

—* w
hee: V2) Ge. Ete: *

\. - ie ©) vhs

PLATE 2

Fig. 13. Amphidinium pacificum sp. nov. Colored by O. Swezy. Ventral view. Note the
refractive granules, probably the products of metabolism, and chromatophores in the body.
xX 626.

Fig. 14. Gymnodinium bicorne sp. nov. Camera drawing by Miss Ruth Merrill. Lateral
view. X 1102.

Fig. 15. Cochlodinium vinctum sp. noy. Viewed from left side. Note the food body closely
embedding a superficial mass of oil droplets, the whole surrounded by a vacuole. Other products
of metabolism, vacuoles and oil droplets, are present. > 1102.

Fig. 16. Cochlodinium virescens sp. nov. Ventral view. The pusules are connected by a
long canal. Food bodies and other products of metabolism present. X 1102.

Fig. 17. Gymnodinium translucens sp. nov. Ventral view. Surface striate, cytoplasm filled
with food body and spherules. X 626.

Fig. 18. Amphidiniwm fastigium sp. nov. Viewed from right side. Surface marked by
ridges, nucleus slightly posterior to the center, cytoplasm filled with food bodies and products of
metabolism. XX 626.

Fig. 19. Gymnodinium gracile Bergh. Ventral view. Nucleus is posterior, cytoplasm
showing vacuoles, rodlets and refractive granules. X 626.

Fig. 20. Gymnodinium auratum sp. noy. Colored by O. Swezy. Ventral view. The
coarsely granular cytoplasm is nearly free from its products of metabolism. Cyst has been
recently formed. > 1102.

Fig. 21. Cochlodiniwm pulchellum Lebour. Eneysted individual with division nearly com-
pleted. Note the proximity of the anterior pore of the posterior daughter individual and the
posterior pore of the anterior daughter. 1102.

Fig. 22. Amphidiniwm scissum sp. nov. Ventral view. Camera drawing by Miss Inez
Smith. Nucleus is posterior without visible chromatin, two large colored food masses near center
of body. X 1323.

Fig. 23. Cochlodinium lebourae sp. nov. Sinistroventral view. Both pusules joined to form
single canal, food bodies present in cytoplasm. Organism enclosed in thin-walled eyst. >< 1102.

Fig. 24. Gymnodinium heterostriatum nom. sp. nov. Ventral view. Surface heterostriate,
food body and other products of metabolism present in cytoplasm. X 1102.

Fig. 25. Cochlodinium faurei sp. nov. Dextroventral view. Note abundance of food bodies
and oil droplets in cytoplasm, products of metabolism. X 1102.

[542]

[ KOFOID—SWEZY] PLATE 2

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA, VOLUME 5&

mane

PLATE 3

Fig. 26. Gymnodinium amphora sp. noy. Ventral view. The peripheral layer of color is
shown only at the margins. Note the fatty, refractive bodies, rodlets, ete., with brownish food
mass near the center. X 626.

Fig. 27. Gymnodinium incisum sp. nov. Colored by O. Swezy. Ventral view. Note the
partly digested Pouchetia with ocellus nearly intact. > 1102.

Fig. 28. Gyrodinium truncus sp. noy. Dextroventral view. Food bodies and fatty spherules
present. > 1102.

Fig. 29. Cochlodinium conspiratum sp. nov. Dextroventral view. Food bodies present in
cytoplasm. Ochraceous pigment near girdle. > 1102.

Fig. 30. Gymnodinium lira sp. nov. Sinistrolateral view. Note the large grain of sand
and peripheral vacuoles. Surface ridges are double contoured. > 1102.

Fig. 31. Gymnodinium agile sp. nov. Ventral view. Note presence of chromatophores and
food bodies, with refractive granules, products of metabolism. The periplast is double contoured
and may be the initial stage of cyst formation. > 1102.

Fig. 32. Gymnodinium pachydermatum sp. nov. Ventral view. Peripheral layers of color
shown only at the margins. Food bodies and rodlets present. 626.

Fig. 33. Gymnodinium costatum sp. noy. Ventral view. Food bodies and other products
of metabolism present. Surface carinae shown at apices only. Nucleus posterior to distal
junction of girdle and suleus. > 626.

Fig. 34. Gymnodinium dogieli sp. nov. Ventral view. Peripheral layers of color shown
only at margins. Cytoplasm filled with products of metabolism. Nucleus in posterior part.
x 626.

[544]

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA, VOLUME & [ KOFOID—SWEZY] PLATE 3

PLATE 4
Fig. 35. Gymnodinium dissimile sp. noy. Colored by O. Swezy. Ventral view. X 1102.

Fig. 36. Amphidinium vasculum sp. noy. Colored by O. Swezy. Ventral view. Note the
differentiated ectoplasm, food bodies and radial rodlets. Nucleus is spheroidal body in posterior
part. Compare with Gymnodinium dogieli (pl. 3, fig. 34). >< 626.

Fig. 37. Gymnodinium multistriatum sp. nov. Colored by O. Swezy. Ventral view.
Nucleus lies at the left of the posterior junction of girdle and suleus. Cytoplasm densely filled
with vacuoles. X 626.

Fig. 38. Gyrodinium pingue (Schiitt). Ventral view. Food bodies present. Note character
of surface striae. 1102.

Fig. 39. Gyrodinium flavescens sp. nov. Colored by O. Swezy. Sinistroventral view.
Greatly elongated nucleus is in predivision stage. Food bodies present. 1102.

Fig. 40. Gymnodinium lunula Schiitt. Eneysted stage prior to formation of zooids.
x 1102.

Fig. 41. Gymnodinium canus sp. noy. Ventral view. Nucleus lies between girdle and
posterior flagellar pore. Fatty globules and other products of metabolism present. > 626.

Fig. 42. Gymnodinium sphaericum sp. nov. Ventral view. Body somewhat distorted.
Predivision stage of nucleus. Cytoplasm filled with rodlets and other products of metabolism.
< 1102:

Fig. 48. Gyrodinium spirale (Bergh). Food bodies present. Nucleus anterior. Posterior
pusule greatly enlarged. >< 626.

Fig. 44. Gymnodinium herbaceum Kofoid. Original drawing by C. A. Kofoid; colored by
O. Swezy. Note food vacuoles filling the cytoplasm with chromatophores also present. X 881.

Fig. 45. Cochlodinium elongatum sp. nov. Colored by O. Swezy. Eneysted stage with
nucleus recently divided. 626.

Fig. 46. Gyrodinium biconicum sp. nov. Dextroventral view. Food bodies present. Pre-
division stage of nucleus. > 1102.

Fig. 47. Polykrikos kofoidi Chatton. Ventral view. Food bodies present. Note the four-
zooid condition of the cytoplasm with only two nuclei present. Nematocysts conspicuous. X 639.

Fig. 48. Gyrodinium viridescens sp. noy. Ventral view. Nucleus near center of body.
SiO:

Fig. 49. Torodinium robustum sp. nov. Colored by O. Swezy. Viewed from left side.
Elongate pusule. > 1102.

[546]

[ KOFOID—SWEZY] PLATE 4

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA, VOLUME 5

Sh Wcewewes ee a ~

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PLATE 5

PLATE 5

Fig. 50. Gyrodinium melo sp. nov. Ventral view. Note the presence of both food bodies
and green chromatophores. Girdle is verging towards the Cochlodinium type. 1102.

Fig. 51. Gymnodinium puniceum sp. noy. Ventral view. Cytoplasm is filled with food
bodies. Nucleus lies on the left side of the body, posterior to the girdle. > 1102.

Fig. 52. Gymnodinium contractum sp. nov. Ventral view. Food bodies present. Epicone
furrowed. > 1102.

Fig. 53. Cochlodinium augustum sp. nov. Ventral view. Food body present. Nucleus is
ellipsoid near center of body. This species represents the maximum of torsion of the body in
the group. 1102.

Fig. 54. Gyrodinium capsulatum sp. nov. Ventral view. Note the double cyst enclosing
the body. Surface color shown only at the margins. This approaches the Gymnodinium type
of girdle. > 1102.

Fig. 55. Gymnodinium lunula Schiitt. Six zooids present, only one of which shows the red
granule of the single mother cell. X 1102.

Fig. 56. Gymnodinium heterostriatwm nom. sp. noy. This shows the presence of an ingested
Cochlodinium. The nucleus is anterior. 626.

Fig. 57. Gymnodinium doma sp. nov. Ventral view. Food body present. Note the unusual
size of the pusule. Peripheral color shown only at margins. X 626.

Fig. 58. Gymnodinium ovulum sp. noy. Ventral view. Large food mass nearly fills body.
* 1102.

Fig. 59. Gymnodinium multiliniatum sp. noy. Ventral view. Note peripheral zone of
rodlets. X 626.

Fig. 60. Cochlodinium clarissimum sp. noy. Ventral view. Note the peripheral zone of
pink vacuoles. The body at the left is the nucleus. Long ellipsoidal food body near it. >< 1102.

[548]

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA, VOLUME 5& [ KOFOID—SWEZY] PLATE 5

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PLATE 6

Fig. 61. Pouchetia maxima sp. nov. Viewed from right side. Food bodies present. Note
the posterior vent through which a food mass has been ejected. This cytoplasmic skirt is soon
withdrawn. X 626.

Fig. 62. Gyrodinium maculatum sp. nov. Dextroventral view. Large food body present.
Violet-colored pigment abundant. > 1102.

Fig. 63. Gymnodinium abbreviatum sp. noy. Ventral view. Food bodies present. Note
irregularities in the surface due to the superficial alveolar layer. X 1102.

Fig. 64. Gyrodinium postmaculatum sp. nov. Ventral view. Antapical agglomeration of
pigment. X 722.

Fig. 65. Gymnodinium lineopunicum sp. nov. Viewed from right side. Epicone occupied
by an ingested Pouchetia. Pomegranate-purple pigment abundant. 722.

Fig. 66. Pouchetia subnigra sp. nov. Viewed from right side. Note strands of melanin
granules. Nucleus greatly elongated. X 603.

Fig. 67. Cochlodinium radiatum sp. nov. Ventral view. Food body present. Note the
pusular canal connecting both pores, peripheral splashes of aster-purple pigment abundant.
* 1102.

Fig. 68. Nematodinium partitum sp. nov. Viewed from the right side. Note the ingested
Gymnodinium. Nematoeysts present. Diffuse type of ocellus. X 837.

Fig. 69. Gymnodinium violescens sp. nov. Ventral view. Food bodies present. Nucleus
is ellipsoidal body in the center. Violet pigment abundant. X 1102.

[ KOFOID—SWEZY] PLATE 6

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA, VOLUME 5&

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Fig. 70. Gyrodinium fulvum sp. noy. Sinistroventral view. Surface is heterostriate. Note
unusual development of anterior pusule. The longitudinal flagellum was attached at its tip to
small particle and vibrated in a cone, following the direction of the arrow. > 1102.

Fig. 71. Cochlodinium atromaculatum sp. nov. Ventral view. Melanin granules present
along girdle. Nucleus is long ellipsoidal body centrally located, cytoplasm filled with colorless
vacuoles. 626.

Fig. 72. Gyrodinium spumantia sp. noy. Ventral view. Cytoplasm foamlike, completely
filled with vacuoles, nucleus spheroidal near the center. XX 626.

Fig. 73. Gyrodinium flavidum sp. nov. Ventral view. Cytoplasm filled wtih vacuoles of
varying sizes. XX 626.

Fig. 74. Protodinifer tentaculatum sp. nov. Viewed from left side. Note stout, posterior
prod, large food body and other products of metabolism. Girdle is short, fading dorsally.
X< 1102.

Fig. 75. Gymnodinium cinctum sp. nov. Colored by O. Swezy. Ventral view. Cyst closely
investing body. Note unusual shape of pusule and peripheral chromatophores. 1102.

Fig. 76. Gyrodinium ochraceum sp. noy. Ventral view. Surface striate, nucleus centro-
anterior, pusules connected by slender canal. Pigment in granules scattered through peripheral
zone. X 626. ‘

Fig. 77. Gyrodinium culeus sp. noy. Ventral view. Cytoplasm foamlike, nucleus dorsad
of anterior flagellar pore. Note rose-red pigment granules. 1102.

Fig. 78. Cochlodiniwm distortum sp. nov. Colored by O. Swezy. Viewed from right side.
Nucleus anterior, pigment granules strung on surface striae. Probably a somewhat distorted
specimen. XX 626.

Fig. 79. Cochlodinium citron sp. nov. Viewed from left side. Nucleus anterior. Note
numerous oil droplets, rodlets, and other products of metabolism in cytoplasm. > 1102.

Fig. 80. Cochlodinium pulchellum Lebour. Colored by O. Swezy. Dextrodorsal view.
Note unusual length of girdle and amount of torsion of body. Nucleus posterocentral. < 1102.

Fig. 81. Gyrodiniwm dorsum sp. noy. Ventral view. Nucleus in posterior half of body,
food body in anterior part. X 1102.

Fig. 82. Gyrodinium ochracewm sp. nov. Dextroventral view. Individual after the pig-
ment granules (fig. 76) had collected into band along the girdle. This later pinched off small
granules until it presented the same appearance as in figure 76. X 626.

[552]

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA, VOLUME 5 [ KOFOID—SWEZY] PLATE 7

PLATE 8

Fig. 838. Gymnodinium sulcatum sp. noy. Colored by O. Swezy. Ventral view. Food
body present. Hypocone marked by yellowish ridges. Rose-red coloring collected into granules
at apices. XX 1102.

Fig. 84. Pouchetia purpurescens sp. nov. Viewed from right side. Camera drawing by
Miss Pirie Davidson; colored by O. Swezy. Yellow-ochre food body. Note unusual position of
ocellus at right of suleus. > 1102.

Fig. 85. Cochlodiniwm rosaceum sp. noy. Viewed from left side. Individual with ingested
Pouchetia which is enclosed in food vacuole. Body is somewhat distorted. > 1102.

Fig. 86. Gymnodinium rubrum sp. nov. Ventral view. Perinuclear zone present. Rose-
red pigment abundant. Girdle verging towards the Gyrodinium type. X 626.

Fig. 87. Pouchetia purpurata sp. nov. Viewed from left side. Food body present. Note
strings of melanin granules. 1102.

Fig. 88. Gymnodinium rubricauda sp. noy. Ventral view. Food bodies present. Colored
pigment aggregated into granules. X 1102.

Fig. 89. Pouchelia voracis sp. nov. Sinistroventral view. Note the double cyst enclosing
this individual. Food bodies present near ocellus. Superficial layer of rose red shown only at
margins. X 1102.

Fig. 90. Pouchetia rubescens sp. noy. Dextrodorsal view. Food bodies present. 583.

Fig. 91. Gyrodinium postmaculatum sp. nov. Ventral view. Food bodies present. Super-
ficial layer of color not fully shown except at margins. > 1102.

[554] -

[ KOFOID—SWEZY] PLATE 8

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA, VOLUME 5&

- PLATE 9 .
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PLATE 9
Fig. 92. Cochlodiniwm helix (Pouchet) Lemm. Viewed from right side. Large food body
present. Pusules connected by canal. X 1102.

Fig. 93. Cochlodinium cavatum sp. nov. Viewed from left side. Organism enclosed in
double cyst. Note ventral excavation of body. X 1102.

Fig. 94. Gyrodinium glaucum (Lebour). Colored by O. Swezy. Long rodlets in cytoplasm
as shown in text figure are omitted. > 1102.

Fig. 95. Gyrodinium fissum (Schiitt). Colored by O. Swezy. Ventral view. Peripheral
zone of radial rodlets shown only at margins. X 1102.

Fig. 96. Protopsis neapolitana Kofoid. Original drawing by C. A. Kofoid; colored by 0.
Swezy. Ventral view. Food bodies present. Note small size and diffuse type of melanosome.
< 1102.

Fig. 97. Gymnodinium hamulus sp. nov. Camera drawing by Miss Inez Smith. Ventral
view. Nucleus is spheroidal body near anterior flagellar pore. X 1102.

Fig. 98. Amphidiniwm turbo sp. noy. Colored by O. Swezy. Ventral view. X 1102.

Fig. 99. Cochlodinium turbineum sp. nov. Viewed from right side. Remains of yellow-
ochre food body in eytoplasm. X 1102.

Fig. 100. Gymnodinium flavum sp. noy. Camera drawing by Miss Inez Smith; colored by
O. Swezy. Ventral view. Note the presence of food bodies and yellow chromatophores. X 1463.

Fig. 101. Cochlodiniwm pirum (Schiitt) Lemm. Unusual size of nucleus may be prepar-
atory to division. > 1102.

Fig. 102. Gyrodinium caudatum sp. nov. Ventral view. Note the unusual type of eyst.
Food bodies present. XX 1102.

Fig. 103. Gyrodiniwm obtusum nom. sp. nov. Colored by O. Swezy. Ventral view. Pusules
connected by slender canal. > 1102.

Fig. 104. Cochlodinium virescens sp. nov. Ventral view. Food bodies present. Pusules
connected by canal. X 1102.

Fig. 105. Cochlodiniuwm catenatum Okamura. Colored by O. Swezy. Chain of four zooids.
x 626,

Fig. 106. Gyrodiniwm ovoideum sp. nov. Colored by O. Swezy. Ventral view. Food body
present. >< 626.

[556]

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA, VOLUME 5 [ KOFOID—SWEZY] PLATE 9

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Fig. 107. Cochlodinium miniatum sp. noy. Camera drawing by Mrs. J. R. Michener.
Viewed from lateral side. Food bodies present. Nucleus is large body centroposterior, adjacent
to brownish food mass. Coral-red pigment. X 626.

Fig. 108. Cochledinium volutum sp. noy. Note unusual branching of anterior pusule.
Nucleus is anterior. XX 1102.

Fig. 109. Gyrodinium herbacewm sp. nov. Camera drawing by Miss Pirie Davidson.
Dextroventral view. Nucleus anterior, food body posterior. 1102.

Fig. 110. Gymnodinium submarinum sp. noy. Ventral view. Nucleus elongate near center
of body. Food body present. > 1102.

Fig. 111. Amphidinium dentatum sp. noy. Ventral view. Note enlarged, connected pusules.
Nucleus sinistrocentral. Peripheral green chromatophores. > 1102.

Fig. 112. Gyrodinium virgatum sp. noy. Ventral view. Note the asymmetrical posterior
end. Nucleus surrounded by perinuclear, vacuolate zone. Coral-red pigment. > 1102.

Fig. 1138. Cochlodinium scintillans sp. nov. Viewed from right side. Food bodies present.
«1102:

Fig. 114. Pavillardia tentaculifera sp. nov. Viewed from right side. Peripheral color
shown only at margins. Note peculiar type of nucleus. Xx 1102.

Fig. 115. Cochlodiniwm convolutum sp. nov. Dextroventral view. Predivision stage of
nucleus. Note elongated eyst. > 1102.

Fig. 116. Gyrodinium rubricaudatum sp. noy. Ventral view. Note antapical agglomerated
pigment. X 672.

Fig. 117. Gyrodinium corallinum sp. nov. Ventral view. Note peripheral, vacuolate zone
of nucleus. Coral-red pigment abundant. X 626.

[558] *

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA, VOLUME 5& [ KOFOID—SWEZY] PLATE 10

PLATE 11

Fig. 118. Pouchetia violescens sp. nov. By an oversight the complete outline of the lens
was omitted. Viewed from right side. Food body present. Transverse flagellum thrown for-
ward into suleus. Pigment diffuse. XX 626.

Fig. 119. Pouchetia maculata sp. nov. Viewed from right side. Food body present. Black
pigment abundant. > 1102.

Fig. 120. Pouchetia violescens sp. nov. Viewed from left side. Pigment was diffuse, as
in figure 118, when first noted, but it soon began to collect into masses and strands, leaving the
cytoplasm colorless. Black is omitted from melanosome in the figure. 626.

Fig. 121. Pouchetia alba sp. nov. Dextrodorsal view. Nucleus anterior. Food bodies
present. Note diffuse type of melanosome. X 626.

Fig. 122. Nematodinium armatum (Dogiel). Viewed from right side. Nucleus anterior.
Nematoeysts conspicuous. XX 626.

Fig. 123. Proterythropsis crassicaudata sp. nov. Viewed from right side. Food body
present. > 1102.

Fig. 124. Nematodinium torpedo sp. noy. Dorsal view. Food bodies present. Nematocysts
anterior. 1102.

Fig. 125. Pouchetia poucheti sp. nov. Dextroventral view. Nucleus is ellipsoidal body
near center. Food bodies present. Note diffuse type of ocellus. > 1102.

Fig. 126. Pouchetia atra sp. nov. Dorsal view. Predivision stage of nucleus. Food body
present. Note presence of granules thrown out of the body but still retained in the cyst. X 1102.

[560]

[ KOFOID—SWEZY] PLATE 11

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA, VOLUME 5&

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Fig. 127. Erythropsis hispida sp. nov. Ventral view. Note peripheral reticular layer.
Nucleus dorsad to ocellus. 626.

Fig. 128. Erythropsis scarlatina sp. nov. Dextroventral view. Pigment in prod. Nucleus
anterior. Profuse scarlet pigment peripheral anteriorly, in center of cytoplasm posteriorly.
xX 626.

Fig. 129. Erythropsis cornuta (Schutt). Dextroventral view. Pusules connected by slender
eanal. Transverse flagellum thrown forward out of girdle. Retractor fibrillae extend forward
from prod. X 626.

Fig. 130. Erythropsis cxtrudens sp. noy. Viewed from right side. Transverse flagellum
thrown forward out of girdle. Pusules branched. X 626.

Fig. 131. Erythropsis minor sp. noy. Ventral view. Transverse flagellum thrown forward
out of girdle. Posterior flagellum present. 1102.

Fig. 132. Erythropsis labrum sp. nov. Ventral view. Prod strongly retracted, showing
fibrillae. Diffuse type of ocellus. Branched pusules. Cuticular markings of pale green. X 626.

Fig. 133. Erythropsis pavillardi nom. sp. nov. Viewed from right side. Prod extended,
showing fibrillae. Transverse flagellum thrown out of girdle. Ocellus integrated, conspicuous.
x 626.

Fig. 134. Erythropsis richardi sp. nov. Ventral view. Prod retracted. Nucleus dorsad
to ocellus. Cuticular layer of pale, blue-green bodies. X 626.

[562]

VOLUME

MEMOIRS OF THE UNIVERSITY OF CALIFORNIA,

F.

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QL Kofoid, Charles Atwood

368 The free-living

D6K6 unarmored dinoflagellata
Biological

& Medical

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