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WISCONSIN GEOLOGICAL AND NATURAL HISTORY SURVEY

W. O. HOTCHKISS. Director

BULLETIN NO. 57

SCIEN1IFIC SERIES NO. 12

Phytoplankton of the Inland
Lakes of Wisconsin

Part I

Myxophyceae, Phaeophyceae, Heterokonteae, and
Chlorophyceae exclusive of the Desmidiaceae.

BY
GILBERT MORGAN SMITH

MADISON, WIS.

PUBLISHED BY THE STATE
1920

Wisconsin Geological and Natural History Survey

BOARD OF COMMISSIONERS.

EMANUEL L. PHILIPP,

Governor of the State.

EDWARD A. BIRGE, President.

President of the University of Wisconsin.

President of the Wisconsin Academy of Sciences, Arts, and Letters.

CHARLES P. GARY, Vice-President.

State Superintendent of Public Instruction.

STAFF OF THE SURVEY, 1919.

ADMINISTRATION:

William 0. Hotchkiss, State Geologist, Director and Superintendent.

In immediate charge of Geology Division.
Ernest F. Bean, Assistant State Geologist.
Lillian M. Veerhusen, Chief Clerk.
Frances Walker, Clerk and Stenographer.
Angeline Doll, Clerk.

GEOLOGY DIVISION:

William 0. Hotchkiss, In charge.

Ernest F. Bean, Geologist, Mineral Land Classification.

T. C. Chamberlin, Consulting Geologist, Pleistocene Geology.

E. O. Ulrich, Consulting Geologist, Stratigraphy, by cooperation of the

U. S. G. S.

H. R. Aldrich, Geologist.
Clare Gillis, Geologist.
R. H. Whitbeck, Geographer.
T. J. Dunnewald, Field Assistant and Analyst.

F. T. Thwaites, Geologist, Well Records, Educational Rock Collection.

NATURAL HISTORY DIVISION:
Edward A. Birge, In charge.
Chancey Juday, Lake Survey.

DIVISION OF SOILS:

A. R. Whitson, In charge.

W. J. Geib, Inspector and Editor.

:-.[. J. Dunnewald, Field Assistant and Analyst.

II. \V. Stewart, Field Assistant and Physicist.

TABLE OF CONTENTS

Page

Preface 1

Introduction 5

List of lakes investigated 13

Analytical key to the genera 21

Myxophyceae 'J6

Phaeophyceae 65

Heterokonteae 79

Culorophyceae 88

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PREFACE

The general name plankton is given to the organisms whicl: live li-ea-
floating in the deeper parts of lakes and ponds ; the plant individuals
being designated the phytoplankton and the animal the zooplankton.
Investigations have shown that there is a very special algal flora liv-
ing exclusively in the plankton, in addition to the chance wanderers
from the littoral, or marginal, region which do not multiply when in
the plankton. These will be designated as the euplanktonts and tycho-
planktonts respectively in this work. There is still another group of
organisms found in lakes, namely those which thrive equally under
littoral or pelagic conditions. This group will be referred to as the
facultative planktonts. Attempts have been made to differentiate be-
tween organisms of these three groups by the Wests, Teiling, and
others, although a different terminology has been used. Since the
question of a proper habitual classification for any particular species
will always be a matter of individual opinion, I have indicated at the
end of the description my conception of the natural habitat of the
organisms found in the lakes of this state.

It is only within the past twenty -five years that the phytoplankton has
been studied, and our knowledge of the various members constituting
this specialized flora has come almost exclusively from European phyco-
logists. William West, G. S. West and Pritsch in England; Chodat
and Bachmann in Switzerland ; Lemmermann, Schmidle, Schroder and
Volk in Germany; von Keissler, Pascher and Woloszynska in Austria-
Hungary; and Wesenberg-Lund in Denmark have been the chief stu-
dents of European phytoplankton. The central African lakes have
been investigated by G. S. West, Schmidle, and Woloszynska. G. S.
West and Playfair have studied the phytoplankton of Australia. With
the exception of Miss Snow's work on Lake Erie nothing was known
concerning the taxonomy of North American phytoplankton at the
time the present work was undertaken, the pioneer work on the micros-
copy of the Massachussetts and Brooklyn water supplies being of little
value to the systematist since determinations were not carried beyond
the genus.

These studies of Wisconsin lakes, carried out under the auspices of
the Wisconsin Geological and Natural History Survey, were commenced
in the fall of 1913. Field work was continued during the summers of

2 PREFACE

1914—15-16-17 and all lake areas of the state have been visited during
the progress of the investigation. Collections have been made from
the lakes around Madison and Ocoiiomowoc during the entire season
that they are open. The June, August and early September flora of
the northeastern lakes is represented, while the northwestern lakes were
visited for two successive seasons during August. Only single collec-
tions were made from the northern lakes so that the data for any par-
ticular one of them are undoubtedly very fragmentary.

The limits of the survey are determined by the political boundaries
of the state and not by ecological or regional unity. There is a con-
tinuation of the southeastern lake group in northeastern Illinois; of
the northeastern lake group in the northern peninsula of Michigan ; and
of the northwestern lake area in Minnesota. However, variation in
depth and surface area together with variation in chemical content of
Wisconsin lakes gives a sufficient range of habitat to cover conditions
found in almost all other parts of the world if temperature and altitude
are excluded. The cosmopolitan nature of phytoplankton, therefore,
makes this work of value to the student of these microorganisms in
other sections of the United States or even other continents, and he wil]
probably find a majority of the species in any region represented in
the Wisconsin flora. There is a temptation to include species that have
not been observed in order to round out the work for the student in
other parts of the world. This practice has been followed in certain
algal floras and while it may be helpful to the general student, it causes
endless confusion to the phytogeographer. Only those species are in-
cluded in this flora which have been collected from the state.

Descriptions of plankton algae are scattered through a large number
of periodical publications and transactions of learned societies, many
with only a limited circulation, so that considerable effort has been
spent in giving full and correct citations for the original descriptions.
When subsequent descriptions have been better or have given more
characteristic figures references are also made to them. A great deal
of time has also been spent making camera lucida drawings since an
accurate figure is frequently more valuable than a description. Draw-
ings of the various species of a genus are generally on the same scale,
but there has been no attempt to draw the different genera on the same
scale. The finer details of cytological structure, such as the nature of
the chloroplast or structure of the pyrenoid, are frequently lost in pre-
served material ; so all of the Chlorophyceae, with the exception of the
Desmidiaceae, the Phaeophyceae, Heterokonteae and the Myxophyceae,
have been drawn from living material.

The original plan for the study of Wisconsin lake algae included those
attached to rocky shores or lying among the macroscopic vegetation in
the quieter portions of lakes in order to get the relation between the

PREFACE 3

benthos and the plankton, but it soon became apparent that limitations
of both time and space precluded an adequate presentation of the lit-
toral flora; attention, therefore, has been confined to phytoplankton
since the second season's work. The great amount of material 011 the
phytoplankton has necessitated dividing the work into two portions;
the material included in the present volume, and the Desmidiaceae and
Bacillareae which are reserved for a later one. A considerable amount
of work has been done already on these two groups and it is hoped that
the complete report can be published shortly.

Phycologists are generally agreed on the broader principles of algal
classification but naturally differ on minor details. The classification
here adopted for the Myxophyceae is used almost universally. The
group of flagellates with brown chromatophores is frequently consid-
ered more animal than plant. One section, the Chrysomonadineae,
where there are golden brown chromatophores, seems to be sufficiently
related to the Phaeophyceae to warrant placing them in a description
of plankton algae and in the arrangement of the group I have followed
Pascher's classification. Since Luther's establishment of the Hetero-
konteae, the question of whether to recognize this group as a separate
class or a division of the Chlorophyceae has arisen. The evidence
seems fairly clear, however, that the origin of the group is from a
primitive flagellate of the Chloramoeba type and since this phylogenetic
starting point is so markedly different from the phylogenetic starting
point of the Chlorophyceae (the Polyblepharidaceae) I feel that the
two should be considered distinct classes. The classification used is
that of G. S. West, although it should be noted that he considers the
Heterokonteae a division of the Chlorophyceae. I have also, with a
few exceptions, followed West's arrangement of the Chlorophyceae.
It is hoped that the keys found in this work will prove usable. They
are based solely upon characters of the species described herein; so
will be of no value for those not mentioned.

During the seasons of 1916 and 1917 the field work was assisted by a
grant of money from the United States Bureau of Fisheries ; and the
extension of these studies to the lakes of northwestern Wisconsin has
thus been made possible.

The University of Wisconsin,
Department of Botany,
February, 1919.

:

INTRODUCTION

Geography and geology of Wisconsin. The state of Wisconsin lies
between Lake Superior, Lake Michigan and the Mississippi river and
has an area of 56,066 square miles, cr an area somewhat larger than
England. Its greatest breadth is about 295 miles and greatest length
320 miles. Within its borders are numerous lakes, the total number
probably reaching well into the thousands, with an estimated surface
area of about 1500 square miles. They vary in size from small lakelets
and ponds that cover but a few acres, to Lake Winnebago with an
area of 215 square miles. The great majority of the lakes, however,
have less than a square mile of surface area. There is likewise great
variation in depth, but for the most part they are shallow since the
deepest (Green Lake) has a maximum depth of 237 feet and only a
few have a depth of over a hundred feet. Certain phycologists have
tried to differentiate between the plankton floras of ponds (heleoplank-
ton) and lakes (limnoplankton). The lakes of this state grade so im-
perceptibly from the "pond" to the "lake" type that it has been im-
possible to distinguish between the two. To set arbitrarily a surface
area of a square mile and depth of 25 feet as the maximal limits for a
pond would involve many difficulties ; since the state presents such ex-
amples as Beasley Lake with a surface area of 0.019 square miles and
a depth of 51 feet or Lake Winnebago with a surface area of 215 square
miles and a maximum depth of 21 feet. I have, therefore, listed all
bodies of water as lakes but have given, in Table 2, all available data
on area and depth for those desiring to recapitulate into heleoplank-
ton and limnoplankton.

There are, roughly speaking, three lake areas in the state ; the south-
eastern, northwestern and northeastern, all of which owe their origin
to glaciation. These lake areas are not uniformly distributed over the
state since the glacier invading this region was divided into lobes and
lakes are found in greatest abundance along the terminal and kettle
moraines of these various lobes. The southwestern portion of the state
possesses no lakes since it lies in a non-glaciated region. The south-
eastern lake area includes several scattered moderately sized lakes and
groups of smaller lakes some of which are among the deepest in the
state. The majority of them lie in a region of kames and pitted plains,
where the pits and lake basins owe their origin to the burial and sub-

6 INTRODUCTION

sequent melting of large irregular blocks of ice. The Oconomowoc,
Lauderdale and Waupaca lake groups are of this type. A few of
the larger and deeper lakes, as Green and Mendota, are situated in
valleys eroded by preglacial streams that were possibly modified by
glacial action and then closed by the building of a morainal dam which
impounded the waters of the present lake.

The northeastern lake group lies chiefly in Vilas, Oneida and Iron
counties. There are hundreds of lakes in this area and their closeness
of position may readily be inferred from the fact that while the largest
of them, Trout Lake, covers only 6.5 square miles the 346 lakes and
ponds in Vilas county occupy 140 square miles or over 15 percent of
the area of a county nearly as large as Rhode Island. In few parts of
the world are there more lakes to the square mile. Parts of the State
of Minnesota, the Province of Ontario, and Finland furnish the
only parallel. These lakes are small, irregularly shaped, and connected
by streams with most irregular courses. They are all glacial in origin
and formed either by shallow depressions of the ground moraine, hol-
lows in outwash plains, or damming of recessional moraines. The en-
tire region is so deeply buried by the glacial drift that no lake is due
to a damming of a preglacial valley. This entire region also contains
numerous swamps (muskegs) characteristics of a poorly drained area.

The northwestern lake area lies in Barron, Polk, Burnett, Washburn,
and Sawyer counties. In general it is similar to the northeastern lake
area in structure and origin but the lakes do not occupy so great a
portion of the land's surface. It has been suggested that some of the
lakes in this region were formed before the last glacial invasion or Late
Wisconsin glacial epoch. Here we find a few lakes formed by a dam-
ming of preglacial valleys; Bone, Beaverdam, and Wapagossett lakes
for example.

The mean average temperature of Wisconsin varies from 6.6° C. in
the southern portion to 3.3° C. in the northern. The state has a mean
summer temperature similar to that of France, Germany, or south-
eastern England (14.5° to 18°) ; the average winter temperature is com-
parable to that of northern Sweden or central Russia (-5.4° to -8.8°).
All lakes in the state are frozen over during the winter, ice forming
during November and December and lasting until March or April in
the southern ones, while on some of the northern lakes ice appears in
October and remains until the latter part of May. The midsummer
surface temperature of the northern lakes is 18°-24° C. and 20°-26°
in the southern lakes.

The altitude of the lakes in the northeastern part of the state varies
from 1550-1700 feet above sea level; in the northwestern area 1050-
1350 feet, and from 750 to 900 feet in the southeastern. These differ-
ences in elevation are too slight to be of any biological significance.

INTRODUCTION 7

Likewise differences in the amount of mean annual precipitation, which
range from 28-44 inches in various parts of the state, need no discus-
sion since rainfall in all regions is sufficient to maintain lakes at their
normal level.

The underlying geological formations are, however, of prime import-
ance and have a marked influence on the distribution of plankton or-
ganisms, especially the plankton desmids. Within the state are found
areas of igneous, metamorphic, and sedimentary rocks each of which
have a different direct influence on the chemical environment of the
plankton organisms. The underlying rock formations of the south-
eastern lake area are the Niagara limestone of the Silurian; the Cin-
cinnati shale, Galena limestone, Lower Magnesian limestone and St.
Peter sandstone of the Ordovician. In the northwestern lake region
is found the Cambrian Potsdam sandstone, the Ordovician Lower Mag-
nesian limestone, together with areas of Keeweenawan trap rock and
Precambrian granites. The northeastern area is entirely Precambrian
granites.

Overlying all of these regions is a mantle of glacial drift some of
which is local in origin while other constituents have been transported
from distant regions. This ground moraine in southeastern Wisconsin
varies in thickness from a few feet on hill tops to over 400 feet in the
bottom of preglacial valleys. Mechanical analyses show that 13% con-
sists of crystalline rocks transported from Canada while the remaining
87% is local sand- and limestone. In the northeastern lake area the
glacial mantle varies from 75-100 feet in thickness with a maximum
depth of 350 feet at the southern boundary of the area. This glacial
accumulation is not the result of one ice invasion but of several; the
last, and the one which left the most material, came from the north-
east and transported the conspicuous sand deposits of Vilas and north-
ern Oneida counties from the sandstone region of northern Michigan.
Previous ice invasions came from the northwest and their deposits, in
some instances, have not been disturbed by succeeding invasions. None
of the drift in this region is calcareous so that all soils are acid in
character. The mantle of drift in the northwestern area varies from
500 to a few feet in thickness and is composed of material from granitic
and sandstone regions. There is, however, a certain amount of lime
in the drift at the southern limit of the lake area.

Chemical composition of the lake waters. Birge and Juday* have
made investigations on the chemical composition of the waters of Wis-
consin lakes in connection with their biochemical studies. They divide
the waters into three general classes; soft, medium, and hard. These

* Birge, E. A. and Juday, C. The inland lakes of Wisconsin. The dissolved
gases of the water and their biological significance. Bull. 22 Wis. Geol. and
Nat. Hist. Survey. (Sci. Ser. 7.) pp. 1-259. 1911.

8 INTRODUCTION

varying degrees of hardness are due to the combination of the carbon
dioxide with calcium and magnesium to form carbonates, the fixed
(CaC03 and MgC03) and the half -bound (CaC03.H2C03 and
MgC03.H2C03). In neutral and acid lakes the two types of carbon
dioxide are present in equal amounts but in alkaline lakes there is an
excess of fixed carbon dioxide. This is due to the ability of the chloro-
phyll bearing organisms to draw upon the half-bound carbon dioxide
as a source of supply after the disappearance of the free carbon diox-
ide. The amounts of magnesium and calcium vary from lake to lake
and there is an almost continuous series from those having the softest
waters to those having the hardest. They consider those lakes whose
average fixed carbon dioxide does not exceed 5 cc. per liter as soft
water lakes, while medium waters have 6-22 cc. of carbon dioxide per
liter and the hard waters from 23-50 cc. per liter. The carbon dioxide
content varies with the depth at which the sample is taken and also
with the season of the year; some of the medium class lakes, for ex-
ample, have a sufficiently low content at times to qualify as soft water
lakes. All of the soft and medium waters, with the exception of Devils
lake in Sauk county, are located in the northeastern and northwestern
lake areas and many of them have sufficient free carbon dioxide to
give an acid reaction with phenolphthalein. The hardwater lakes are
all in the southeastern area and the upper stratum in them is alkaline
to phenolphthalein for the greater part of the year.

Aside from the question of the hardness of the water complete min-
eral analyses of a few lakes are also available. These results are em-
bodied in Table 1 and represent average conditions. They are taken
from the data given by Birge and Juday and their data show that
there is a seasonal variation and a vertical variation in the amounts of
certain elements present. These variations in vertical distribution are
well shown in their Fig. 7, p. 106 (I. c.) The lakes of southeastern
Wisconsin contain a rich flora of Chlorophyceae, Myxophyceae and
Phaeophyceae, both in quantity and quality. In the northern lake
areas the total volume of the plankton is, generally speaking, consider-
ably smaller and quite different in character. These lakes have a con-
siderable desmid flora in many instances, while with the exception of
one or two species desmids are not found in the hard waters of the
southeastern region. The volume of phytoplankton that can be pro-
duced in a lake is primarily dependent upon the available supply of
carbon dioxide for photosynthesis. In the northern lakes this supply
is chiefly the carbon dioxide dissolved in the water but in the southern
lakes there is in addition considerable quantities of half -bound carbon
dioxide which may be drawn upon after the free carbon dioxide is ex-
hausted. It is not surprising, therefore, that the southern lakes with
greater supplies of potential food materials have a greater production

INTRODUCTION

of algae. There are certain factors modifying the growth of algae in
hard water lakes ; in those deep ones which become thermally stratified
in the summer most of the algae are restricted to the epilimnion. The
thickness of the epilimnion is in part dependent upon the size and shape
of the lake, since the wind is more effective in keeping water in circula-
tion on large surfaces. Algae are continually sinking to the bottom and
giving rise to carbon dioxide and nitrogenous products. In the deep

TABLE 1. — Results of mineral analyses stated in parts per million. These show
average content of various depths and at different dates.

Si02

Fe2Os

Al2t)3

Ca

Mgr

Na

K

COs

HCOs

S04

Cl

Devils

2.2

0.7

3.2

1.1

1.0

8.1

8.1

8.2

Trout

13.0

1.1

6.7

2.~>

0.8

0.3

0.0

28.0

6.4

3.0

Kawagruesaga ....

16.5

6.2

7.2

2.8

2.6

1.7

0.0

37.0

7.9

2.7

Owen . .

9.9

2 7

13 0

3 (i

0.5

33.3

0.0

l.S

Rainbow

17.5

2.2

22.2

15.5

2.3

3.3

4.0

105.0

8.9

4.3

Mendota

4.4

1.4

23.3

22.7

3.7

2.2

2.5

105.2

13.5

3,0

Geneva

9.5

1.1

20.7

26.9

4.4

2.5

3.7

110.5

13.2

4.8

Okauchee

17.6

1.5

34.3

25.9

3.2

1.4

0.0

66.0

13.9

1,9

Beasley

16.5

1.5

38.9

21.8

2.4

2.0

1.5

111.0

2.0

3,1

lakes these products of decay are chiefly in the hypolimnion and are
not immediately available for reutilization by other algae. In shal-
low lakes without thermal stratification these products are immediately
available for the vegetative activities of algae. Shallow lakes, there-
fore, support proportionally larger algal floras. The restriction of
the desmids to the soft water lakes was first pointed out by the Wests
and their observations have been confirmed in Wisconsin (Birge and
Juday, I. c. p. 138). An examination of the chemical analyses of such
soft water lakes as Devils, Trout and Kawaguesaga (Table 1) shows
that in these lakes which contain numerous desmids the calcium and
magnesium content is relatively small. The influence of calcium and
magnesium on the distribution of desmids may be that of a direct in-
hibition of growth or the absence of these elements may permit an
acid condition which is favorable for the growth of desmids. Data on
organic matter and distribution of nitrogen in lakes of the state are
lacking. The scarcity or abundance of available nitrogen is doubtless
an important factor in the volume of algae produced in a lake, and it
is a well known fact that as regions become more thickly settled and
drainage entering the lake becomes richer in nitrogenous material the
growth of plankton algae becomes more luxuriant.

10 INTRODUCTION

Methods of collection and study. All plankton collections have been
made with nets. In general both the bolting silk net and the cotton
disc net were used. The bolting silk net of No. 20 bolting cloth (new
No. 25) is that described by Juday*. The cotton disc net is made by
attaching a filter designed for purifying drinking water (Jones Mod-
ern Filter made by the Jones Mfg. Co., Boston, Mass.) to the bottom
of an eighteen inch cone of canvas whose mouth is held open by a light
metal ring ten inches in diameter. In using this filter a special cot-
ton disc supplied by the manufacturer is placed in the filter and the
whole apparatus drawn through the water. The algae collect on the
disc and when there is a sufficient accumulation the disc is taken from
the filter and shaken in a bottle with a small amount of water which
removes the algae. This net catches many of the smaller organisms
that pass through the bolting silk (the nannoplankton) and it is also
very useful in obtaining samples by dipping when no boat is available.
Whenever possible samples have been gathered by towing the nets at
the surface and all collections have been made in the deep parts of all
lakes to avoid, as far as possible, the littoral flora. No attempt has
been made to study the vertical distribution of the algae in any lake.

In studying the flora of any region a field laboratory was established
and with that as a center excursions were made to the surrounding
lakes. By traveling from lake to lake in an automobile collections
could be made in the morning and the material studied the same after-
noon and the following day. In the northeastern lake area where
there are no roads in many cases, but where lakes are close together,
they can be visited by portaging a canoe from lake to lake. Collections
have been made from row boats, where they were obtainable, but in a
few instances collections had to be made by repeatedly dipping the
net after wading to where the water was 3-4 feet deep or from rafts.
Upon returning to the temporary laboratory equipped with compound
microscope, camera lucida, and drawing materials, the living specimens
were studied and numerous pencil camera lucida drawings made of all
doubtful, interesting, or rare organisms, together with notes on occur-
rence and ocular micrometer measurements of known forms. No ob-
servations were made on desmids or diatoms at this time. The study
of the Chlorophyceae, Myxophyceae and Phaeophyceae in the living
condition is particularly important since many of them do not preserve
well and certain features such as cilia, chloroplasts, and contractile
vacuoles are lost when material is preserved. All drawings of one
species are mounted on the same sheet and corresponding notes on an-
other. These are then filed in species and genus covers in the usual

* Juday, C. Limnological apparatus. Trans. Wis. Acad. Sci. Arts & Lett.
18s: 566-592. 1916.

INTRODUCTION H

manner for herbarium specimens so that all data on any particular spe-
cies are immediately accessible. The figures for the plates of this work
have been redrawn from camera lucida sketches made in field labora-
tories. The confined space of a vial is not favorable for algae and the
more delicate forms, as Uglenopsis, frequently go to pieces after stand-
ing a few hours. It is impossible to have the vials uncorked while
transporting them from station to station but they should be opened
immediately on return to field headquarters. I have also found it
helpful to keep them as cool as possible and have stored them in hotel

I

refrigerators until ready to make observations. Formalin has proven
a satisfactory means of preserving the desmids and diatoms until their
study can be taken up during the winter months.

The following list of simple reagents is helpful in studying the vari-
ous structures of living algae. Cilia of motile forms are more easily
seen when the cells have been rendered immobile by mounting in a 1%
cocaine solution. Mounting in a dilute aqueous acid fuchsin also helps.
Pyrenoids can be recognized by the grouping of the starch grains when
the latter have been stained with iodine. It is difficult to strain pyre-
noids of living cells. Gelatinous envelopes are best demonstrated by
Errera's method of mounting in dilute India ink which gives the col-
orless envelope the appearance of a halo around the cells in contrast
to the dark background of water containing the ink. Nuclei can be
demonstrated by Strasburger's solution of methyl green in 1% acetic
acid. Simple microchemical tests are Sudan III for fats, iodine for
starch, zinc chloriodide for cellulose, and Ruthineum Red for pectin.

Lakes studied. The following table gives a list of lakes in the state
from which plankton samples have been taken. All known hydro-
graphic maps, morphometric data, general descriptions of many lakes
and general maps of the various lake areas have been given by Birge
o,nd Juday* so that any one wishing further data concerning a particu-
lar lake is referred to their work. They have not, however, mapped or
discussed many of the smaller lakes of the northern regions. Since
most of the lakes in the state were named by the settlers of the region
considerable poverty of vocabulary is noticed and Round, Mud, Devils,
Long, and Sand are repeated many times. In other instances Indian
(Chippewa) names have been retained as the white man settled the
region. In these also there is a certain amount of duplication and
Sishebogema (lake with many bays) or Pokegama (side or branch lake)
may be cited as examples. It is too bad that these names have not been
retained to a greater extent, but certain of the English names like
Razorback, Crawlir^ Stone, Lost Canoe, Tenderfoot or Fishtrap are not

* Birge, E. A. and Juday, C. The inland lakes of Wisconsin. Bull. 27: Wis.
Geol. & Nat. Hist. Survey. (Sci. Ser. 9). pp. 1-137. 1914.

12 INTRODUCTION

without interest. This is not the place, however, for the legends on
the origin of these peculiar names nor for a discussion of the occurrence
of several French names in the list. In order to avoid misunder-
standing the town and range in which the lake occurs is given. When
more than one lake with the same name has been visited, a serial num-
ber has been added and both the lake name and serial number are used
in giving stations for the various algae.

INTRODUCTION

13

TABLE 2. — Tablt giving available data on location and size of lakes visited during the
course of this investigation. The fint column refers to the page on which a map
of the lake may be found in Birge and Juday, The inland lakes of Wisconsin, the
hydrography and morphometry. Bull. 27. Wu. Oeol. and Nat. Hist. Survey.

il^

• V

Page
map-
ped

Lake

County

Town

Range

Length
(Miles)

Maxi-
mum
breadth
(miles)

Maxi-
mum
depth
(Feet)

Area

(Acres)

Adelaide

Vilas

43N

5E

.47

.32

68.9

45.0

Rusk

34N

8W

1.06

.30

IL'O

Balsam

Polk

34N

17W

3.00

1.00

18.0

1,785.6

Bass (1)

Vilas

40N

HE

.50

.24

Bass (2)

Vilas

42N

6E

.93

irr

Bass (3) .

Burnett ..

40N

14W

Bear (1)

Bari'on

34N

14W

.45

.40

Bear (2)

Polk

33N

17W

.88

.59

120

Bear (3)

Barron-

36N

12W

4.50

1.00

Bear Trap

Washburn.
Polk

33N

17W

1.05

.48

104

Beasley

Waupaca

21N

HE

.25

.10

51.2

13.5

Beaver (1)

Vilas

44N

5E

.44

.25

40

Beaver (2)

Waukesha . . .

8N

18E

1.10

.44

49.0

305.4

120

Beaverdam

Barron

35N

14W

3.80

.75

91.9

1,267.2

Bettine . .

Vilas

36N
43N

13W
7E

* 75

.56

120

Biff

Polk

32N

18W

.80

.65

1:0

Bigr Butternut

Polk

33N

36N

17W

1.20

.60

21.3

384.0

120

Big McKenzie

Burnett

40N

14W

2.25

1.05

116

Big St Germain

Vilas.

40N

8E

2.62

1.25

116

Birch (1)

Vilas

43N

5E

1.50

.74

120

Birch (2)

Washburn ...

37N

10W

.90

.70

57.4

243.2

120

Birch Island

Burnett

40N

14W

2.10

irr.

Blake

Polk

35N

16W

1.90

irr.

Bloom

Burnett.

37N

18W

Blue Gill

Vilas

43N

7E

.12

.09

120

Bone

Polk

35N

1BW

4.80

1.00

49.2

2,054.4

116

Boulder

Vilas

36N
42N

7E

2.25

1.20

19.7

614.4

74

Browns

Racine

2N

19E

1.25

.75

23.0

390.4

Bullhead

Vilas.

3N

40N

6E

.31

.26

75

Camp

Kenosha

IN

20E

1.50

1.00

19.7

256.0

Canteen

Vilas

4SN

7E

.31

.17

116

Carroll

Vilas

39N

7E

1.30

.47

23.0

288.0

Carson (see Flora)

40N

14

INTRODUCTION

TABLE 2. — (Continued)

Page
map-
ped

Lake

County

Town

Range

Length
vMiles)

Maxi-
mum
breadth
(miles)

Maxi-
mum
depth
(Feet)

Area

(Acres)

11G

Catfish ....

Vilas

39N

10E

2.87

irr.

19.7

902.4

116

Catherine

Vilas

40N
38N

HE

6E

2.25

Irr.

27.9

608.0

Ti

Kenosha

IN

20E

.72

.35

PVift. in

Polk

35N

13W

120

Chetac • « •

Sawyer . . .

37N
38N

9W

6.40

1.10

190

Chetek

Barron

33N

10W

3.25

irr.

120

PI am

Burnett

38N

IfiW

3 84

1.92

Clare

Polk

39N
35N

16W

.55

.36

116

dear

Oneida

39N

7E

2.10

irr.

82.0

921.6

116

Clear Crooked *

Vilas

42N

7E

1.40

1.12

32.8

672.0

Vilas

43N

8E

.69

.36

116

Crab

Vilas

43N

6E

2.12

1 . 35

44.3

1,318.4

116

Cranberry

Vilas

40N

HE

1.25

.70

11.5

332.8

116

Crawling Stone

Vilas

40N

5E

2.40

1.65

93.0

1,600.0

Burnett

38N

16W

1 44

.44

39N

6E

76

25

120

Polk

34 N

17W

2.80

.70

39.4

806.4

70

Wai worth . . .

2N

18W

16E

3.75

1.10

56.7

1,813.2

Burnett. .

41N

14W

1.00

.30

30 32

Devils (1)

$auk

UN

6E

1.25

.61

43.2

360.8

I'O

Tipvil^ (2)

36N

11W

1 60

40

Devils (3)

Vilas ....

43N

8E

.44

.26

Polk

37N

17W

60

.60

' T~)nr»lr

36N

13W

50

30

Barron

36N

13W

00

.25

Burnett .

38N

17W

Burnett

38N

17 W

74

Eagle

Racine

3N

20E

1.31

1.00

13.1

486.4

I'O

East

Polk

33N

18W

74

.52

75

Elizabeth

Kenosha

IN

19E

2.62

.87

26.2

800.0

116

Pence

Vilas

40N

5E

3.25

2.10

93.0

3,492.0

120

Fish

Burnett. .

40N

14W

1 30

.55

116

Fish trap

Vilas

42N

7E

1.50

.62

29.5

326.4

116

Flora .

Vilas..

43N

7E

1.31

irr.

1 Listed as Clear Lake by Birge and Juday.

INTRODUCTION

15

TABLE 2 — (Continued)

Page
map-
ped

Lake

County

Town

Range

Length
(Miles)

Maxi-
mum
breadth
(Miles)

Maxi-
mum
depth
(Feet)

Area
(Acres)

116

52
66

120

Found

Vilas

40N

8N

IN

2N
44N

36N
42N

15N
16N
4N

40N
35N

44N
40N
44N

42N

43N
39N

34N
IN
33N
34N
33N
34N
33N
42N
43N
43N
39N
6N
42N
43N

39N
40N
40N

8N
41N
38N
Juday

8E
17E

16E
17E

5E

13W

7E

12E
13E

16E

8W
9W
17W

5E

HE

5E

7E
8E
6E

14W
20E
18W
15W
17W
17W
8W
6E
6E
8E

6E
7E
10E
HE
13W

7E

8W
9W
4E
5E
17E

8E
17W

1.06
.94
7.50
.56
1.60
1.31
7.40
1.09
3.40
1.77
1.51
.58
.47
2.00
.18
.60
.75
1.22
2.50
.80
.25
1.75
1.00
.44
.58
4.25
3.00
1.68
.34
5.65
2.00
2.70
1.50

.69
.44
2.00
.33
.30
.64
2.00
.66
2.10
.50
irr.
.14
.20
1.00
.14
.25
.37
.40
1.00
.62
.20
.65
irr.
.34
.21
irr.
2.25
.80
.19
1.90
irr.
1.12
.90

Fowler

Waukesha ...
Walworth —
Vilas

50.0
142.0

ET 83.5
5,451.3

Geneva

George
Granite

Grassy

Vilas

92
76
120
120
116

Green (1)

Green Lake. .
Walworth
Sawyer ,

237.0
56.8
47.6

7,342.4
277.9
3,462.4

Green (2)

Grindstone

Half Moon

Polk

H arris

Vilas

Helen (1)

Vilas

Helen (2)

Vilas

116

High ..

Vilas

31.2

761.6

Hill

Oneida

Hillnian .

Barron

75
120
120
120

Hooker

Kenosha

23.0

64.0

Horse . . .

Polk

Horseshoe8 (1)

Polk

59.0

800.0

Horseshoe (2)

Polk .

Howey

Polk

120
118

Island

Rusk

47.6

435.2

Jag

Vilas

Jennie

Vilas.

Jones

Vilas

116

26

Kawaguesaga

Oneida

55.8
31.4

2067.2
3,145.2

Kegonsa

Dane

Kimball

Washburn...
Vilas

Kitten

120
116
52
116

• • > • •

»I

Lac Court Oreilles. . .
Lac du Flambeau.. . .
Lac la Belle

Sawyer

67.2
49.2
46.4
39.4

5 248.0
1,280,0
1,137.5
640.0

Vilas

Waukesha . . .
Vilas

Laura

Lake of the Woods. .
^isted as Big Horsesho

Burnett

e by Birge and

^C

*

16

INTRODUCTION

TABLE 2 — (Continued)

Page
map-
ped

Lake

County

Town

Range

Length
(Miles)

Maxi-
mum
breadth
(Miles)

Maxi-
mum
depth
(Feet)

Area
(Acres)

Lily

Burnett

41N

14W

Lindy

Burnett

40N

14W

Little Bass (1)

Vilas

42N

6E

.28

19

Little Bass (2)

Polk

34N

17W

Little Bear

Vilas

43N

6E

.69

.44

Little Butternut

Polk

36N

17W

.60

35

Little Crooked

Vilas

42N

6E

1.06

irr

Little Doctor

Burnett

38N

17W

,45

30

Little Rice (1)

Rusk

33N

8W

70

40

118

Little Eice (2»

Vilas

42N

7E

.76

38

120

Little Wood

Burnett

38N

18W

82

48

Long(l)

Burnett

41N

14W

1 85

35

120

Long (2)

Polk

34N

17W

1.70

55

24 6

384.1

Long (3)

Vilas

40N

5E

1 40

.60

55 8

448 •

104

Long (4)

Waupaca . . .

21N

HE

94

36

77 7

108 4

Loon

Barren

34N

14W

1.00

.45

116

Lost

Vilas

40N

8E

1 69

86

118

Lost Canoe

Vilas. ..

42N

7E

1 25

38

41 0

204 8

120

Loveless

Polk

34N

17W

1 00

32

21 3

153 6

Lynx

Vilas

43N

7E

75

66

Marion

Vilas

44N

5E

.37

19

104

Marl

Waupaca ....

21N

HE

.31

19

60 6

21.3

75

Mary

Kenosha . . .

IN

19E

1.20

70

26 2

275.2

12

Mendota

Dane.. ..

7N

9E

5 90

4 go

84 0

9 729 8

Mercer

Oneida

8N
39N

5E

1.30

69

Meronk

Burnett

40N

14W

Meta

Vilas

40N

HE

.64

.26

76

Middle

Walworth

4N

16E

1.60

45

50 0

284.<

120

Middle McKenzie 3 . .

Burnett

40N

14W

1.10

.90

76

Mill

Walworth ....

4N

16E

75

49

50 0

296.4

20

Monona

Dane

7N

9E

4.16

2.40

74 0

3,482.7

Mud (1)

Polk

34N

10E
17W

.66

28

Mud (2)

Vilas

40N

5E

81

56

114

Mud (3)..

Vilas..

39N

7E

.87

.36

1 Listed as McKenzie lakes.

INTRODUCTION

17

TABLE 2 — (Continued)

Pape
map-
ped

Lake

County

Town

Range

Length

(Miles)

Maxi-
mum
breadth
(Miles)

Maxi-
mum
depth

(Feet)

Area

(Acres)

104

Mud (4)

Waupaca

21N

HE

.13

.06

32.0

9.7

Mudhen

Burnett

38N

17W

1.68

1.10

116

Muskallon£fe . .

Vilas

41N

7E

1.93

irr

'20

Nancy

Washburn . . .

42N

13W

2.00

1.25

54

Waukesha .. .

7N

18E

2.75

1.12

94 4

917.6

54

54

Nashotah (Upper). . .
Nashotah (Lower) . .
Nell

Waukesha .. .
Waukesha ...
Vilas

7N
7N
44N

17E
17E

5E

.81
.79
.46

.40
.25
15

57.2
46.2

136.7
100.3

54

54

Nemahbin (Upper)..
Nemalibin (Lower). .
Nicaboyne

Waukesha ...
Waukesha . . .
Burnett

7N
7N
41N

17E

17E
14W

1.05

.93

.56
.60

62.0
35.2

271.1

265.5

116

Vilas

44N

5E

1.00

69

North Twin

Polk

33N

1GW

.92

.30

Number One

Sawyer . ..

37N

9W

.25

(8

Oak

Burnett

'JON

I4W

.70

.45

46

Waukesha. . .

7N

17K

1.75

.85

62 6

631.3

46

Okaucht e

Waukesha.. .

8N

17E

2.37

1.80

94.0

1,057.0

Old Taylors

Waupaca ....

22N

18E
HE

104

Otter

Waupaca ....

22N

HE

.40

.03

40.0

14.5

120

Bayfleld . .

44N

7W

6.25

irr

88.6

2,032.0

75

Paddock

Ivenosha

43N
IN

T.OE

.62

.37

31.0

9.5

116

Palmer

Vilas

43N

8E

1.75

1.25

14.8

614.4

116

Pardee . •

Vilas

44N

4E

.94

87

G3

Waukesha . .

7N

18E

4.50

1.30

45.0

2,298.0

Pike

Polk

33N

19E
16W

1 18

.30

40

Pine (1)

Waukesha . .

feN

18E

2.30

1.05

90.0

755.7

Pine (2) . .

Polk

;>SN

17W

.66

.28

Pine Tree

Polk

3°N

15W

.92

irr

116

Plum

Vilas

•UN

7E

4.20

1.25

50.8

1,088.0

120

Pokegrama (1)

Washburn . .

42N

8E
12W

2.40

.60

23.0

505.6

11G

Pokeframa (2)

Vilas

ION

5E

3.25

l.SO

42.6

1,216.0

120

Pokegrama (3)

jBarron

41N

33N

10W

3.50

.70

Poor Farm .

Polk

S3N

16W

104

Pope

Waupaca . . .

21N

HE

.22

.11

40.6

16.2

120

Poolar . .

Polk. .

3SN

18W

.72

.38

18

INTRODUCTION

TABLB 2. — (Continued)

Page
map-
ped

Lake

County

Town

Kan ere

Length
(Miles)

Maxi-
mum
breadth
(Miles)

Maxi-
mum
depth
(Feet)

Area
(Acres)

8

Poygan

Waushara . . .

19N

13E

7.70

3.50

10.8

10,992.2

I'O

Barron

33N

11W

6. CO

.70

104

Rainbow (1)

Waupaca

34N
22N

HE

.62

.55

95.1

137.5

llfi

Rainbow (')

Vilas

44N

5E

.63

.44

116

Razorback . . .

Vilas

41N

8E

1.10

.90

31.1

352.0

Red Bass

Vilas

43N

7E

.40

.13

Reserve

Sawyer

39N

8W

1.00

.55

Rife (1) . .

Barren

35N

11W

2.75

.60

Rice (9)

Vilas

42N

6E

.45

.30

Rock

Vilas

44N

"E

1.12

.37

Burnett

40N

14W

Vilas

40N

7E

1.14

.25

Round (')

Vilas

43N

6E

.62

.40

Round (2)

Polk

33N

mv

.58

.41

Round (3)

Polk

32N

17W

.26

.20

"

104

Round (4)

Waupaca ....

22N

HE

.55

.35

66.6

106.2

Rozen

Vilas

40N

7E

.68

.50

116

Rudolph

Vilas

43N

7E

.52

.22

120

St. Croix

Douglas

45N

11 W

4.00

.55

19.7

1,030.4

Sand (1)

S8N

12W

16 W

120

Sand (?)

Burnett

40N

15W

1.70

1.45

120

Sand (3)

Polk

SoN

18W

1.22

.45

116

Sand4 (4)

Vilas

42N

7E

1.65

.87

67.2

793.6

San ford

Vilas

43N

6E

.77

.40

120

Shell

Washburn . . .

S7N

12W

3.25

2.50

49.2

3,200.0

120

Silver (1)

3SN
36N

13W
13 W

75

Silver (2)

Kenosha . . . .

IN

20E

1.25

.87

42.6

582.0

58

Silver (3)

Waukesha... .

7N

17E

.97

.56

44.0

231.9

Sishebo^rema

Vilas

39N

5E

2.50

irr.

tjs

Soft

Waukesha

4(IN

7N

17E

.32

.20

•^n\

5E

3'

31

116

gquiiT^ 1

Oneida. '.....

39N

5E

3.75

1.00

33.8

1,568.0

South Pi'fll »

Vilas

43N

6E

68

.20

120

Spirit

Burnett

37NT

1,S\V

1.70

1.00

24.6

640.0

116

Star . .

Vilas..

41N

8E

2.12

1.60

26.2

1,152.0

4 Listed as White Sand Lake by Birge and Juday.

INTRODUCTION

2 i( Vutiiiueti)

Pape
map
ped

Lake

County

Town

Ransre

Length

(Miles)

Maxi-
mum
breadth
(Miles)

Maxi-
mum
depth
(Feet)

Area

(Acres)

St iv i tor

Vilas

42N

39N
43N
4 ON
22N

4SN

6E
5E
5E
6E
HE
8E

.-!-!
.75
.56
.24
.45
l.CO

.28

.."7
..'-(I
.(IS1
.31
l.CO

Sunday

Onokla

Tamarack

Vilas

Tank

Vilas

104
116

Taylor
Tenderfoot

Waupaoa
Vilas .

55.7
27.9

51.2
646.4

Tied Canoe 6

Travis

Polk

33N

41N
42N
43N

43N
34 N
34N
35N
33N

fiN

7N
34N

39N
41N
42N

43N
34N

15N
20N
42N

21N

17W

6E
7E

5E

5E
14W
14W
13W

IfiW
17W

10E

16W
9W
5E
6E
7E
17W
17E
7E
HE

116
110
116
120
120
120
120
24

Trout

Vilas

4.50
1.25
2.25
1.50
2.30
1.70
8.50
4.20
1.77
2.60
2.75
.56
.87
.85
28.00
1.21
.09

2.40
.80
.63
.45
.JO
1.20
1.20
1.40
.40
.65
"..00
.45
.60
.64
10.40
.84
.07

115.0
47. P
43.0

4,160.0
640 .-0
793.6

Turtle (North)

Vilas ..

Turtle (South)

Vila^

Turtle (Lower)

Rarr* >n . . .

Turtle ( Upper)

Barron

23.0

4^:0.0

Vermilion

Barroi . .

Wapagossett"
Wauljesii

Polk

27.9
36.6

1,452.8
2,034.4

Dane

White Ash

Polk

120

no

Whitefish

Sawyer

73.8

896.0

White Sand

Vilas

Whitney

Vilas .

116

120
92
111!
104

Wildcat

Vilas

Wild Goose

Polk ..

14.8

21.0

256.11
137,708.0

Winnehatro

Wolf

Vilas

Young's

Waupaca

11.6

3.0

68ee Lost Canoe.

•Listed as Sucker Lake by Birse and Juday.

»>c\

<<£

*

KEY TO THE GENERA BASED UPON THE
VEGETATIVE CHARACTERS.

1. (35) Coloring matter not restricted to definite plastids

Class Myxophyceae 2

.?. (22) Cells solitary or in colonies, never in filaments

Order Coccogoneales 3

3. (12) Ceils solitary or in colonies that never contain more than

a few cells 4

4. ( 7) Cells spherical or hemispherical 5

5. ( 6) Cells without a definite arrangement Chroococcus p. 27

6. ( 5) Cells in a flat plate Merismopedia p. 31

7. ( 4) Cells longer than they are broad 8

8. (11) Individual cells not enclosed by a special gelatinous vesicle 9

9. ( 10) Ends of cells rounded Rhabdoderma p. 46

10. ( 9) Ends of cells pointed Dactylococcopsis p. 47

11. ( 8) Individual cells or groups of cells enclosed by a gelatinous

vesicle Gloeothece p. 45

12. ( 3) Cells in colonies that contain many cells when mature 13

13. ( 18) Cellular arrangement within colony definite 14

14. ( 15) Cells forming a flat plate Merismopedia p. 31

15. ( 14) Cells forming a hollow sphere one cell in thickness 16

16. (17) Center of colony with radiating gelatinous strands

Gomphosphaeria p. 36

17. ( 16) Center of colony without radiating gelatinous strands

Coelosphaerium p. 33

18. ( 21) Cells spherical 19

19. ( 20) Cells densely aggregated Microcystis p. 38

20. ( 19) Cells some distance from one another Aphanocapsa p. 41

21. ( 18) Cells longer than they are broad Aphanothece p. 43

22. ( 2) Cells in simple or branched filaments. .Order Hormogoneales 23

23. (30) Trichomes without heterocysts Family Oscillatoriaceae 24

24. (29) Trichomes solitary or in flocculent readily dissociating

masses 25

25. ( 26) Trichomes containing but one spirally twisted cell

Spirulina p. 49

26. (25) Trichomes containing more than one cell 27

27. (28) Sheaths of filament firm, generally projecting beyond the

trichome Lyngbya p. 52

28. ( 27) Sheath delicate or lacking, not projecting beyond the tri-

chome Oscillatoria p. 50

29. I 24) Trichomes laterally united to form free-floating bundles

which do not dissociate readily Trichodesmium p. 54

30. ( 23 ) Trichomes with heterocysts 31

22 WISCONSIN PHYTOPLANKTON

SI. ( 34) Trie-homes not attenuated Family Nostocaceae 32

22. ( 33) Filaments solitary or interwoven to form flocculent masses

of small size Anabaena p. 55

33. (32) Filaments laterally joined to form small plate-like colonies

of macroscopic size Aphanizomenon p. 61

34. ( 31) Trichomes attenuated to a hair-like point Gloeotrichia p. 63

35. ( 1) Coloring matter in definite chromatophores 36

36. ( 57) Chromoplasts golden brown in color .- 37

37. ( 38) Wall heavily impregnated with silica and definitely marked

with grooves or rows of dots Bacillarieae (see part 2).

38. ( 37) Wall not heavily impregnated with silica

Class Phaeophyceae 39

39. ( 52) Cells generally motile, rarely forming palmella or rhizopo-

dial stages Division Euchrysomonadinae 40

40. (45) Cells with one flagellum Order Chromulinales 41

41. ( 42) Cells naked Chrysamoeba p. 67

42. (41) Cells with a differentiated periplast

Family Mallomonadaceae 43

43. ( 44 ) Cells solitary Mallomonas p. 67

44. ( 43 ) Cells in colonies Chrysosphaerella p. G9

45. ( 40) Cells with two flagella 46

46. ( 47 ) Flagella of equal length Synura p. 70

47. ( 46) Flagella of unequal length Order Ochromonadales 48

48. ( 51) Cells in a definite receptacle Family Dinobryaceae 49

49. ( 50) Receptacles homogeneous, without growth rings. .Dinobryon p. 72

50. ( 49) Receptacles with successive growth rings Hyalobryon p. 75

51. ( 48) Cells never in a definite receptacle Uroglenopsis p. 71

52. ( 39) Cells usually immobile, rarely motile 53

53. ( 54) Cells spherical to ovoid, embedded in a gelatinous mass....

Phaeococcus p. 76

54. ( 53) Cells with pseudopodial processes

Division Rhizochrysidinae 55

55. ( 56) Cells solitary or in irregular colonies Rhizochrysis p. 77

56. ( 55) Cells in a linear series Chrysidastrum p. 78

57. ( 36) Chromoplast grass-green or yellowish-green in color 58

58. ( 69) Chromoplast yellowish-green, with oil not starch the assimi-

lation product Class Heterokonteae 59

59. ( 60) Vegetative cells motile Chlorochromonas p. 80

60. ( 59 ) Vegetative cells immobile 61

61. ( 68) Cells solitary or in colonies, never in filaments

Order Heterococcales 62

62. ( 63 ) Cells epiphytic Peroniella p. 81

63. ( 62) Cells free-floating 64

64. ( G5) Length of cells several times the diameter Ophiocytium p. 85

65. ( 64) Length of cells less than twice the diameter 66

CO. ( (>7) Cells irregularly distributed throughout an ovoid, gelatinous

envelope Chlorobotrys p. 82

67. ( 66) Cells arranged about a common center and enclosed by an

irregular, gelatinous envelope Botryococcus p. 33

68. ( 61) Cells united to form simple filaments Tribonema p. 87

69. ( 58) Chloroplast grass-green, generally with pyrenoids and starch

Class Chlorophyceae 70

WISCONSIN PHYTOPLANKTON 23

70. (71) Cells solitary or in families, divided into two symmetrical

halves with a chloroplast in each half. Median region
generally constricted. .Family Desmidiaceae ('See Part 2)

71. ( 70) Cells not divided into two symmetrical halves and without

median constrictions 72

72. ( 85) Cilia normally present in vegetative cells.. Order Volvocales 73

73. ( 84) Anterior end of cells with two cilia 74

74. ( 75 ) Cells solitary Chlamydomonas p. 90

75. ( 74) Cells in colonies Family Volvocaceae 76

V6. ( 77) Colony a flat plate Gonium p. 94

77. ( 76 ) Colony a hollow sphere 78

78. ( 79 ) Cells mutually compressed Pandorina p. %

79. ( 78) Cells some distance from one another 80

80. ( 83) Colony with not more than 256 cells 81

8.1. ( 82) Asexual reproduction by division of all cells to form daugh-
ter colonies Eudorina p. 95

82. ( 81) Asexual reproduction by division of certain cells to form

daughter colonies Pleodorina p. 96

83. ( 80) Colony generally containing many cells Volvox p. 97

84. ( 73) Anterior end of cells with four cilia Carteria p. 92

85. ( 72) Cilia not present in vegetative cells 86

86. (183) Cells solitary or in colonies, never in simple or branched

filaments Order Protococcales 87

87. (122) Cells solitary 88

88. (121) Cells free-floating 89

89. ( 92 ) Cell shape angular 90

90. ( 91) Angles simple or with spines, never with long setae

Tetraedron p. 115

91. ( 90) Angles with tufts of long setae Polyedriopsis p. 124

92. (89) Cells spherical, ovoid, or elongate 93

93. (116) Length of cells not more than three times the diameter 94

94. ( 109") Cells spherical 95

95. (102) Cell wall smooth 96

96. ( 99) Cells embedded in a gelatinous sheath 97

07. ( 98) Gelatinous sheath lamellated Gloeocystis p. 100

98. ( 97) Gelatinous sheath not lamellated Planktosphaeria p. 103

99. ( 96) Cells not embedded in a gelatinous sheath 100

100. (101) Wall lamellated Gloeotaenium p. 115

101. (100) Wall not lamellated Chlorella p. 108

102. ( 95) Wall sculptured, denticulate, or with long spines or setae.. 103

103. (108) Setae or long spines covering the wall 104

104. (107) Wall with setae 105

105. (106) Setae the same thickness throughout, or gradually taper-

ing Golenkinia p. 127

106. (105) Setae visibly thickened in the lower third. .Acanthosphaeria p. 128

107. (104) Walls with long spines Echinosphaerella p. 128

108. (103) Denticulations or ridges covering the walls Trochiscia 108

109. ( 94) Cells ovoid to reniform 110

MO. ( 111 ) Cells reniform Nephrocytium p. 114

111. (110) Cells ovoid 112

112. (113) Walls without setae or spines Oocystis p. 110

113. (112) Walls with spines or setae 114

24 WISCONSIN PHYTOPLANKTON

114. (115) Setae somewhat tapering Lagerheimia p. 129

115. (114) Setae not tapering Franceia p. 131

3 16. ( 93) Length of cells several times the diameter 117

117. (118) Ends of cells produced into setae Schroederia p. 136

118. (117) Ends of cells not produced into setae 119

119. (120) Chloroplast with an axial row of pyrenoids Closteriopsis p. 136

120. (119) Chloroplast without or with one pyrenoid. . Ankistrodesmus p. 134

121. ( 88) Cells epiphytic or epizootic Characium p. 175

122. ( 87) Cells in colonies 123

123. (142) Colonies enclosed by a conspicuous gelatinous sheath 124

124. (125) Cells connected by branching remains of old cell walls

Dictyosphaerium p. 104

125. (124) Cells not connected by branching remains of old cell walls.. 126

126. (137) Cells spherical to ovoid or reniform 127

127. (136) Chloroplast cup to disc-shaped and parietal 128

128. (129) Cells with pseudocilia Tetraspora p. 102

129. (128) Cells without pseudocilia - 130

130. (131) Colonies never containing more than eight cells. .Gloeocystis p. 100

131. (130) Colonies always with at least eight cells 132

132. (133) Cells ovoid to reniform Gloeocystopsis p. 102

133. (132) Cells spherical 134

134. (135) Chloroplasts of old cells cup-shaped Sphaerocystis p. 101

1T>5. (134) Chloroplasts of old cells disciform Planktosphaeria p. 103

136. (127) Chloroplasts star-shaped and central Asterococcus p. 103

1ST. (126) Cells elongate 138

Io8. ( 141) Cells straight 139

139. (140) Colonies with cells in groups of two Elaktothrix p. 139

140. (139) Colonies with cells in groups of 2-4-8 Quadrigula p. 137

141. (138) Cells curved Kirchneriella p. 140

112. (123) Cells not enclosed by a gelatinous sheath 143

143. (156) Colonies always forming a flat plate 144

144. (155) Number of cells, except in rare cases, greater than two 145

145. ( 152 ) Cells quadrately arranged 146

146. (147) Quadrate arrangement apparent in end view of colony

Tetradesmus p. 150

147. (146) Quadrate arrangement apparent in front view of colony.... 148

148. (149) Cells without setae or spines Crucigenia p. 144

1 *9. (148) Cells with spines or setae 150

150. (151) Long setae or spines on outer face of cells. . . .Micractinium p. 125

151. (150) Short spines on outer face of cells Tetrastrum p. 149

152. (145) Cells not quadrately arranged 153

153. (154) Colony a flat circular or oval disc Pediastrum p. 166

154. (153) Colony a single or double row of cells Scenedesmus p. 150

155. (144) Number of cells in colony always two Euastropsis p. 174

156. (143) Colony not forming a flat plate 157

157. (166) Colony enclosed by old cell wall 158

1B8. (165) Wall enclosing colony greatly expanded and homogeneous.. 159

159. (162) Wall with spines or setae 160

160. (161) Setae somewhat tapering Lagerheimia p. 129

161. (160) Setae not tapering Franceia p. 131

162. (159) Wall without spines or setae 163

163. (164) Cells ovoid Oocystis p. 110

WISCONSIN PHYTOPLANKTON 25

164. (163) Cells ovoid to reniform Nephrocytium p. 114

165. (158) Wall lamellated but not expanded Gloeotaenium p. 115

1C6. (157) Colony not enclosed by old cell wall 167

167. (176) Length of cell not more than twice the breadth 168

168. (171) Remains of old cell walls at center of and holding colony

together 169

169. (170) Cells spherical Westella p. 106

170. (169) Cells ovoid to reniform Dimorphococcus p. 106

171. (168) Colonies without remains of old cell wall at center 172

172. (173) Outer face of cells with long setae Micractinium p. 125

173. (172) Outer face of cells with short spines or without ornamenta-

tion 174

174. (175) Cells without spines on outer face Coelastrum p. 160

175. (174) Cells with short spines on outer face Sorastrum p. 162

176. (167) Length of cells several times the breadth 177

177. (178) Colony forming a closed hollow sac Hydrodictyon p. 165

178. (177) Colony not forming a closed hollow sac 179

179. (180) Cells radiating from a common center Actinastrum p. 164

180. (179) Cells not radiating from a common center 181

181. (182) Cells straight or arcuate Ankistrodesmus p. 134

182. (181) Cells markedly curved Selenastrum p. 132

183. ( 86) Cells in simple or branched filaments 184

184. (195) Cells with one to eight chloroplasts, chloroplasts never re-

ticulate 185

185. (192) Chloroplasts parietal 186

186. (191) Chloroplasts laminate to disciform 187

187. (188) Cells in simple filaments Ulothrix p. 179

188. (187) Cells in branching filaments 189

18'9. (190) Setae confined to terminal cells or lacking. . . Stigeoclonium p. 180

190. (189) Setae occurring on any cell of filament Aphanochaete p. 181

191. (186) Chloroplast a spiral band Spirogyra p. 185

192. (185) Chloroplast central 193

193. (194) Chloroplast an axial plate Mougeotia p. 184

194. (193) Chloroplasts stellate Zygnema p. 184

195. (184) Chloroplasts numerous or united to form a single reticulate

mass Cladophora p. 182

26 WISCONSIN PHYTOPLANKTON

Class MYXOPHYCEAE.

Cells solitary, in colonies of definite or indefinite shape, or in fila-
ments but always surrounded by a gelatinous to tough envelope which
is generally hyaline but may be colored. Plants living a free-floating,
sessile, epiphytic or endophytic existence. Cell shape various; spheri-
cal, hemispherical, ovoid, bacilliform, disciform or angular. Cells with
the coloring matter localized at the periphery but not in definite, visible
chromatophores. Color of cells typically blue-green but at times grey,
yellowish, reddish, brownish or nearly grass-green. The color variation
being due to different amounts of the three component pigments, caro-
tin, chlorophyll, and phycocyan; the latter being found only in this
class of plants. Cells containing a single nucleus of a primitive type
(the central body) that contains linin and chromatin but is without a
membrane or nucleole.

Reproduction always asexual, either by vegetative division of cells;
fragmentation of the filaments into smaller portions (hormogones)
which may move a short distance by spontaneous movement and then
come to rest; or by special non-motile reproductive bodies (gonidia and
resting spores) .

KEY TO THE ORDERS.

Cells solitary or in colonies, never in filaments COCCOGONEAI<ES

Cells in simple or branched filaments HOEMOGONEAUBS

Order COCCOGONEALES.

Cells rarely solitary, generally in colonies of regular or irregular
shape, and with the cells definitely or indefinitely arranged within a
copious gelatinous envelope. Colonies living a free-floating, sessile,
epiphytic or endophytic existence. Cells differentiated into a basal
and distal portion or without such differentiation. Cell shape various ;
spherical, ovoid, cylindrical, acicular, or angular.

Asexual reproduction by vegetative division of the cells or, in rare
cases, by a division of the cell contents into non-motile gonidia. Rest-
ing cells and sexual reproduction unknown.

There are two families in the order only one of which, the Chroococ-
caceae, is found in the plankton.

WISCONSIN PHYTOPLANKTON 27

Family CHROOCOCCACEAE.

Cells not differentiated into an apical and basal portion ; rarely soli-
tary, generally in colonies of definite or indefinite shape and always
enclosed by a gelatinous sheath. Cell shape various, and cellular ar-
rangement within the colonial envelope definite or indefinite.

Asexual reproduction by vegetative cell division and the fragmenta-
tion of the colonies. Gonidia formation occasionally taking place in
certain genera.

KEY TO THE GENERA.

Cells solitary or in colonies that never contain more than a few cells.

Cells spherical or hemispherical CHEOOCOCCUS

Cells longer than they are broad.

Individual cells or groups of cells enclosed by a gelatinous

vesicle GLOEOTHECB

Individual cells or groups of cells without vesicles.

Ends of cells rounded RHABDODERMA

Ends of cells pointed DACTYLOCOCCOPSIS

Cells always in colonies that contain many cells when mature.
Cellular arrangement within colony definite.

Cells forming a flat plate MERISMOPEDIA

Cells forming a hollow sphere one cell in thickness.

Center of colony with radiating gelatinous strands . GOMPHOSPHAERIA

Center of colony without radiating strands CoELOSPHAERnrM

Cellular arrangement within colony indefinite.
Cells spherical.

Cells densely aggregated MICBOCYSTIS

Cells some distance from one another APHANOCAPSA

Cells longer than they are broad APHANOTHECE

CHROOCOCCUS Nageli 1849.

Cells spherical, usually hemispherical for some time after division;
solitary or 2-4—8-16 or more united in colonies enclosed by a hyaline
or colored, homogeneous or lamellated sheath; free-floating, sessile, or
epiphytic. Individual cells of colony at times surrounded by a homo-
geneous or lamellated sheath. Cell contents grey, grey-green, blue-
green, olive-green, yellowish, orange, reddish or violet in color; homo-
geneous or granular.

Reproduction by vegetative division of cells in three directions.

KEY TO THE SPECIES.

Sheaths enclosing cells homogeneous.

Cells solitary, in twos, and in fours C. MINUTUS

Cells in colonies of 4-8-16 or more.

Individual cells or groups of cells some distance from one

another C. DISPEBSUS

Individual cells or groups of cells fairly close together. .C. LIMNEHCUS

28 WISCONSIN PHYTOPLANKTON

Sheaths enclosing cells distinctly lamellated.

Diameter of cell and sheath not exceeding 40 n C. TURGIDUS

Diameter of cell and sheath over 60 n C. GIGANTEUS

CHROOCOCCUS MINUTUS (Kiitzing) Nageli. PL 1, Fig. 1.

Gatt. einz. Algen 46. 1849.

Protococcus minutus Kiitzing, Tabulae Phycol. 1: pi. 5.

Cells spherical or hemispherical, solitary or in colonies of 2-4 en-
closed by a wide, spherical, homogeneous, gelatinous sheath. Cell con-
tents pale blue-green to grey, homogeneous or granulose. ( Tychoplank-
tont).

Diam. cells (without sheath) 5-7 p, (with sheath) 6-12 p.; length
(without sheath) 5-10 /A, (with sheath) 5-13 /i.

Wolf (rrr).*

CHROOCOCCUS DISPERSUS (v. Keissler) Lemmermann. PI. 1, Fig. 2.

Arkiv. f. Botanik 2, No. 2: 102. 1904.

Chroococcus minor var. dispersus v. Keissler, Verh. d. zool.-bot. Ges. Wien
52: 311, fig. 6. 1902.

Cells spherical, 4-16 or more united to form spherical, ovoid, or ir-
regular colonies. Individual cells some distance from one another,
or in compact groups that lie some distance from one another within
the colony. Individual cell sheaths frequently confluent with the col-
onial sheath. Cell contents homogeneous, pale to bright blue-green.
(Euplanktont).

Diam. cells (without sheath) 3-4 /JL- (with sheath) 6 p. Distance be-
tween cells or groups of cells 15-20 p..

Browns (rr), Pokegama (1) (rr).

A species that is closely related to C. limneticus but one where the
number of cells in the colony is usually greater, and where the indi-
vidual cells or groups of cells are some distance from one another.

var. minor var. nov. PI. 1, Fig. 3.

Cells smaller than the typical form and with pale grey contents.
(Euplanktont).
Diarn. cells 1. 75-2. 5 /*.

Long (3) (rrr), Middle McKenzie (rr), Palmer (rr).

: The relative abundance of the individual species is shown by the following
symbols; (aaa) very abundant, (aa) abundant, (a) fairly abundant, (ccc) very
common, (cc) common, (c) fairly common, (s) fairly scarce, (ss) scarce,
(sss) very scarce, (r) fairly rare, (rr) rare, (rrr) very rare.

WISCONSIN PHYTOPLANKTON 29

CHROOCOCCUS LIMNETICUS Lemmermann. PI. 1, Fig. 4.

Bot. Cent. 76: 153. 1898; Forschungsbr. a. d. Biol. Stat. zu Pl6n 7: 132, pi. 1,
figs. 22-23. 1899.

Mature cells spherical to subspherical, 4-32 in a free-floating spheri-
cal to ovoid colony. Cells fairly close together and equidistant from
one another within the colony, sometimes in groups of 2-4 but with
the groups lying close together. Cell division in all three planes but
a majority of the cells dividing in the same plane and giving the colony
a somewhat tabular appearance. Many hemispherical cells present be-
cause of the slow maturation after division. Individual cell sheaths
homogeneous and frequently confluent with colonial envelope. Cell
contents homogeneous ; grey, pale to bright blue-green, or olive-green.
( Euplanktont) .

Diam. cells (without sheath) 6-12 //,, (with sheath) 8-14 /t.

Balsam (r), Bear (1) (rr), Bear (2) (rrr), Bear Trap (sss), Beasley (rr),
Beaver (1) (r), Beaver (2) (ss), Big Butternut (r), Birch (1) (rr), Birch (2)
(SB), Birch Island (s), Blake (sss), Bloom (s), Boulder (rrr), Browns (s),
Camp (rr), Catfish (rr), Chetac (r), Chetek (rrr), Cranberry (sss), Dunham
(rr), Dutchmans (r), Eagle (rr), East (rr), Fish (rr), Found (rr), Fowler
(rr), Grassy (rr), Grindstone (rr), Half Moon (rr), Horseshoe (1) (r),
Island (rr), Kawaguesaga (rr), Kimball (rr), Lac Court Oreilles (rr), Lac la
Belle (r), Little Bass (2) (ss), Little Butternut (rr), Little Rice (2) (rr),
Little Wood (sss), Loveless (r), Mary (rr), Middle McKenzie (r), Mill (rr),
Mud (1) (rr), Mud (2) (rr), Mudhen (r), Nicaboyne (r), North Twin (rr),
Oconomowoc (rr), Old Taylors (rr), Pewaukee (rr), Pike (rr), Pine Tree (rr),
Pokegama (1) (r), Pokegama (2) (rrr), Pokegama (3) (rr), Poor Farm (rr),
Poplar (ss), Reserve (sss), Rice (1) (r), Round (3) (rr), Sand (1) (s),
Sand (3) (sss), Sand (4) (rr), Shell (sss), Silver (2) (r), Spirit (r), Squir-
rel (r), Tenderfoot (rrr), Travis (rrr), Upper Nashotah (rr), Upper Nemah-
bin (rr), White Ash (ss), Whitefish (s), Wildcat (rr), Wlnnebago (r), Wolf
(rr).

This is preeminently a plankton species. It is widely distributed
throughout the state and may be the dominant member of the Myxo-
phyceae in lakes with very soft water, but it never occurs in sufficient
abundance to cause the familiar phenomenon of blooming. The cells
are quite variable in both color and size.

var. SUBSALSUS Lemmermann. PI. 1, Fig. 5.

Forschungsbr. a. d. Biol. Stat. zu P16n 8: 84. 1901; Arkiv f. Botanik 2: No. 2:
101, pi. 1, fig. 9. 1904.

Cells spherical to subspherical, 8-16-32 in a somewhat spherical or
broadly ellipsoidal colony with a wide gelatinous envelope. Cell con-
tents homogeneous; pale to bright blue-green. (Euplanktont).

30 WISCONSIN PHYTOPLANKTON

Diam. cells (without sheath) 3.5-4.5 /*; (with sheath) 4.5-5.5 /t.

Big Bass (sss), Blake (rr), Lac Court Oreilles (ss), Owen (ss), Paddock (r).

The chief distinction of this and the following varieties is in the size
of the cells.

var. CAKNEUS (Chodat) Lemmermann. PI. 1, Fig. 6.
Arkiv for Botanik 2, No. 2: 101. 1904.

Cells spherical to hemispherical, 4-8-16 irregularly distributed
throughout a spherical to ovoid gelatinous matrix. Individual sheaths
of cells confluent with the colonial envelope. Cell contents homogene-
ous; color variable, ochraceous, grey, blue-green or olive green. (Eu-
planktont) .

Diam. cells (without sheath) 7-9 p..

Big Bass (ss), Harris (r), Mendota (rr), Nancy (r), Oconomowoc (rr).

var. DISTANS G. M. Smith. PI. 1, Fig. 7.
Bull. Torr. Bot. Cl. 43: 481, pi. 26, fig. 26. 1916.

Cells spherical to hemispherical, 8-32 in a colony and lying some
distance from one another within a spherical to ovoid, hyaline, homo-
geneous, gelatinous, colonial envelope. Individual cell sheaths con-
fluent with the colonial envelope. Cell contents homogeneous, grey to
pale blue-green in color. (Euplanktont).

Diam. cells (without sheath) 6.5-7 /*.

Bear Trap (s), Birch Island (rr), Browns (sss), Cochrane (r), Cranberry
(sss), Lindy (rr), Muskallonge (rr).

var. ELEGANS G. M. Smith. PI. 1, Fig. 8.
Trans. Wis. Acad. Sci., Arts, & Lett. 191: 619. 1918.

Cells circular to semicircular in front view, somewhat flattened in
side view. Colonies enclosed by a spherical, homogeneous, hyaline, gel-
atinous envelope. Individual sheaths of cells conspicuous. Cell con-
tents homogeneous; generally bright blue-green in color. (Euplank-
tont) .

Diam. cells (without sheath) 18-22 /*; (with sheath) 20-26 fi.

Delavan (rr).

CHROOCOCCUS GIGANTEUS W. West. PI. 2, Fig. 1.
Jour. Roy. Micr. Soc. 1892: 741, pi. 10, figs. 59-60. 1892.

Cells ordinarily hemispherical, rarely becoming spherical or ovoid
after division. Solitary or in colonies of two (rarely 3-4) enclosed by

WISCONSIN PHYTOPLANKTON 31

a thick, hyaline, markedly lamellate, gelatinous envelope. Envelope of
individual cells conspicuous, lamellated. Cell contents distinctly gran-
ulose, bright blue-green. (Tychoplanktont).

Diam. cells (without sheath) 54-58 p.; (with sheath) 67-70 ft.

Mary (rrr).

CHROOCOCCUS TURGIDUS (Kiitzing) Nageli. PI. 1, Fig. 9.
Gatt. einz. Algen 46. 1849; G. S. West, Brit. Freshw. Algae 352, fig. 166B- 1904.

Cells hemispherical, spherical, ovoid, or somewhat flattened by mutual
compression. Cells solitary or in colonies of 2-4 (rarely 8) enclosed
by a thick, hyaline, generally lamellated, gelatinous sheath. Individual
cells also with hyaline, lamellated sheaths. Cell contents homogeneous
or finely granulose ; pale to bright blue-green or rarely brownish in
color. ( Tychoplanktont) .

Diam. cells (without sheath) 8-32 /A; (with sheath) 13-40 /*.

Beasley (rrr), Beaver (2) (rr), Browns (IT), Hillman (rr), Horse (rrr),
Oconomowoc (rr), Otter (rr), Rudolph (rr), Sand (2) (rr), Upper Turtle (rr),
Waubesa (rrr).

MERISMOPEDIA Meyen 1839.

Colonies always forming flat, curved, or irregularly twisted plates
one cell in thickness with the constituent cells in rectilinear series and
usually in groups of four. Cells spherical to subspherical with rounded
ends, hemispherical for some time after division. Individual sheaths
of cells rarely distinct, generally confluent with the copious, hyaline,
homogeneous, colonial envelope. Number of cells in colony 1 4000,
cell number a multiple of two in young colonies, not a multiple of two
in old colonies. Cell contents generally homogeneous, rarely with
pseudovacuoles. Color varying from grey through light to bright blue-
green, rarely rose pink to violet.

KEY TO THE SPECIES.

Cells bright blue-green M. ELEGANS

Cells pale blue-green.

Cells some distance from one another M. PUNCTATA

Cells close together (not mutually compressed).

Diameter of cells 1. 5-2 /* M. TENTJISSIMA

Diameter of cells 3-6 /* M. GLAUCA

32 WISCONSIN PHTTOPLANKTON

MERISMOPEDIA ELEGANS A. Braun. PI. 2, Fig. 5.

in Kiitzing, Species algarum 472. 1849; G. S. West, Brit. Freshw. Algae 348:
fig. 162C. 1904.

Colonies small or large, of 16-4000 cells regularly arranged in recti-
linear series and groups of four; with the cell number a multiple of
two in young colonies but becoming irregular in arrangement and num-
ber in old colonies. Colonies flat except when containing many cells.
Cells spherical to broadly ovoid, with homogeneous, bright blue-green
contents. (Facultative Planktont).

Cells 5-7 p. broad, 5-9 /i long.

Carson (rr), Center (rr), Green (1) (rr), Kegonsa (rr), Little Bear (rrr),
Mendota (r), Monona (r), Mud (1) (rr), Nancy (r), Upper Nashotah (rrr),
Waubesa (rr).

This alga is a good example of a typical benthitic organism that is
able to thrive under limnetic conditions. It never becomes a conspicu-
ous member of the plankton but the colonies attain a much larger size
and I have observed specimens 60-70 cells broad and 60-90 cells long.
There is a certain amount of irregularity in such colonies so exact de-
terminations of cell numbers are impossible.

var. major var. nov. PL 2, Fig. 6.

Colonies usually containing many cells. Cell shape the same as in
the typical form. Cell contents homogeneous, bright blue-green. (Eu-
planktont) .

Cells 10-11 n broad, 12-14 /* long.

Beaverdam (r), Lindy (rr).

MERISMOPEDIA GLAUCA (Ehrenberg) Nageli. PI. 2, Fig. 4.
Gatt. einz. Algen 55, pi. 1, fig. D1. 1849.

Colonies generally containing less than 64 cells, compactly and regu-
larly arranged. Cells spherical to broadly ellipsoid, hemispherical for
some time after division. Cell contents homogeneous, generally pale
blue-green. (Facultative Planktont).

Diam. cells 3-5 p..

George (rr), Jones (rrr), Lac Court Oreilles (rrr), Loon (rrr), Meta (rr),
Mill (rr), Waubesa (rr).

This species resembles M. punctata in the size of the cells but differs
in the distance between the cells.

WISCONSIN PH7TOPLANETON 33

MERISMOPEDIA PUNCTATA Meyen. PI. 2, Fig. 3.

Arch. f. Naturgescb. 5*: 67. 1839; Kutzing, Tabulae Phycol. 5: 18, pi. 38, ftp. 3.
1855.

Colonies small, with the cells some distance from one another but
regularly arranged in rectilinear series. Cells spherical to broadly
ovoid or hemispherical. Cell contents homogeneous, grey to pale blue-
green. (Tychoplanktont).

Diam. cells 2.5-3.5 /*.

Big Bass (rrr).

MERISMOPEDIA TENUISSIMA Lemmermann. PI. 2, Fig. 2.

Bot. Cent. 76: 154. 1898; Forschungsbr. a. d. Biol. Stat. zu P16n 7: 132, pi. 1,
fig. 21. 1899.

Colonies rectangular, free-floating, generally with 16-100 cells lying
close together. Rectilinear arrangement of cells soon breaking down
and not evident when there are more than 32 cells in a colony. Col-
onies distorted when of any size. Cells spherical to ovoid, hemispheri-
cal for some time after division. Individual sheath of cells distinct
or confluent with colonial envelope. Cell contents homogeneous; grey
to pale blue-green. (Facultative Planktont).

Diam. cells (without sheath) 1.5-2 jn.

Camp (rr), Little Doctor (rr), Long (3) (r), Mary (rr).

The irregular cellular arrangement is very common in older colonies
and is not due to the size of the colony, since the species is one of the
smallest of the genus, but to irregularities in cell division.

COELOSPHAERIUM Nageli 1849.

Colonies microscopic, free-floating; spherical, ellipsoid, reniform, or
irregular ; enclosed by a delicate, hyaline, homogeneous or radially fibril-
lar, gelatinous envelope. Cells spherical, ovoid, ellipsoid, sub-pyriform
and arranged in a single layer to form a hollow sac just beneath the
periphery of the colonial envelope. Cell contents homogeneous and
grey to bright blue-green ; or reddish and containing numerous pseudo-
vacuoles.*

Reproduction by vegetative cell division in three directions.

*These structures, which are also called gas vacuoles, are found in certain
plankton species of the Myxophyceae. They are minute bodies, which are
reddish through their refractive power, that occur in large numbers in all
cells of the colony. Various functions have been ascribed to them, the most
probable being a means of protection against too intense light, or a giving of
greater buoyancy to the colony.

34 WISCONSIN PHYTOPLANKTON

KEY TO THE SPECIES.

Cells spherical.

Diameter of cells not exceeding 4 /JL C. KUETZINGIAUM:

Diameter of cells over 5 ^ C. DUBIUM

Cells ovoid to ellipsoid C. NAEGELIANUM

COELOSPHAERIUM KuETziNGiANUM Nageli. PI. 3, Figs. 4-5.
Gatt. einz. Algen 54, pi. 1, fig. C. 1849.

Colonies spherical to subspherical, enclosed by a very hyaline, homo-
geneous, gelatinous envelope. Cells spherical to subspherical, forming
a single layer, with the individual cells or pairs of cells some distance
from one another or close together. Cell contents homogeneous, with-
out pseudovacuoles ; usually grey to pale blue-green, rarely bright blue-
green. (Facultative planktont).

Diam. cells 2.25-4 ^ ; diam. colonies 20-90 //..

Balsam (IT), Bass (2) (rr), Bear (3) (r), Bear Trap (rrr), Beaverdam (ss),
Big (ss), Big Butternut (sss), Birch Island (rrr), Blake (ss), Bone (rr),
Browns (rr), Carson (r), Catfish (r), Clam (ss), Cochrane (sss), Crab (rr),
Cranberry (ss), Crawling Stone (sss), Deer (rr), Diamond (rrr), Elizabeth
(s), Eagle (ss), Fence (sss), Fish (rr), Grindstone (rr), Green (2) (rr), Half
Moon (r), High (sss), Hillman (ss), Horseshoe (1) (rrr), Kegonsa (s), Kit-
ten (rr), Island (ss), Lac la Belle (rr), Lindy (rr), Little Bear (rrr), Little
Butternut (r), Little Crooked (rr), Little Rice (1) (ss), Little YvTood (s),
Long (2) (rr), Long (3) (rr), Loveless (sss), Mary (s), Mendota (s), Mer-
cer (rrr), Mill (rrr), Mud (1) (cc), Mud (2) (r), Mudhen (s), Nancy (rrr),
Nicaboyne (rr), North Turtle (ss), Oconomowoc (r), Owen (rrr), Paddock
(ss), Palmer (ss), Pardee (cc), Pewaukee (rr), Pine (2) (rr), Pine Tree (rr),
Pokegama (1) (sss), Pokegama (2) (r), Pokegama (3) (rrr), Poplar (ss),
Reserve (ss), Rice (1) (rr), Rock (sss), Round (3) (sss), Sand (1) (rr).
Sand (3) (rr), Sand (4) (r), Silver (1) (ccc), Silver (2) (ss), South Turtle
(ss), Spirit (ss), Sunday (r), Tamarack (rr), Tenderfoot (sss), Tied Canoe
(rrr), Upper Nemahbin (rrr), Upper Turtle (sss), White Ash (sss), White-
fish (s), White Sand (sss), Wildcat (rr), Wild Goose (rr), Winnebago (rr),
Wolf (r).

The gelatinous sheath is generally so delicate that it is necessary to
use Errera's method of mounting colonies in dilute India ink to demon-
strate its presence. The specific limits of this species as established
by different authors frequently includes C. Naegelianum as a synonym.
C Kuetzingianum and (7. Naegelianum are two well defined species that
differ in colony shape, cell shape, occurrence of pseudovacuoles, struc-
ture of colonial envelope, and relative abundance. C. Kuetzingianum
is a species that is widely distributed throughout the state but one which
rarely becomes a dominant member of the plankton and never occnrs
in sufficient abundance to cause blooming.

WISCONSIN PHYTOPLANKTON 35

COELOSPHAERIUM DUBiuM Grunow. PI. 3, Fig. 7.

in Rabenhorst, Flora Eur. Algarum 2: 55. 1865; Schmula, Beibl. z. Hedwigla
37: (47), figs. 1-2. 1898.

Colonies spherical to irregular, with three or four smaller colonies
frequently enclosed by a common gelatinous envelope. Colonial en-
velope firm, hyaline, and homogeneous. Cells in a single layer and
very close together at the periphery of the colonial envelope. Cell con-
tents homogeneous or with pseudovacuoles ; blue-green in color. (Fac-
ultative Planktont).

Cells 5-7 p, in diameter. Single colonies up to 150 p in diam ; com-
pound colonies up to 300 /x.

Mud (3) (rr).

COELOSPHAERIUM NAEGELIANUM Unger. PI. 3, Fig. 6; PI. 4, Fig. 1.

Denkschr. d. kais. Ak. d. Wiss. Wien 7: 196. 1854; Leitgeb, Mitt. d. naturw.
Ver. Steiermark 2, Heft 1: 72, pi. 2, figs. 1-6. 1869; Borge, Bot. Not. 1900:
10, pi. 1, figs. 5*-5b. 1900.

GomphospJtaeria Naegeliana (Unger) Lemmermann. Kryptogamenfl. d.
Mark Brandenburg 3, Algen 1: 80, 44, fig. 19. 1907; Bachmann, Arch. f. Hy-
drobiol. u. Planktonkde. 3: 60, figs. IIP-III6. 1908.

Colonies spherical, ovoid, renif orm or irregular ; with a wide, hyaline,
gelatinous envelope that is at times radially fibrillar in structure. Cells
ovoid to ellipsoid, radially arranged in a single layer some distance be-
neath the periphery of the colonial envelope, usually close together but
not mutually compressed. Cell contents rarely homogeneous and pale
to bright blue-green or grass-green ; usually with numerous pseudovacu-
oles and reddish to brownish in color. (Euplanktont).

Cells 2-3 /x broad ; 3.5-6 /* long.

Adelaide (ss), Amicoy (ss), Balsam (ss), Bear (1) (s), Bear (2) (rr),
Bear (3) (s), Bear Trap (sss), Beaverdam (cc), Big (ccc), Big Butternut
(r), Big McKenzie (ss), Big St. Germaine (rr), Birch (1) (ccc), Birch (2)
(aa), Birch Island (rrr), Blake (rr), Bloom (ss), Bone (ss), Boulder (rr),
Browns (rr), Camp (c), Catfish (aa), Center (aa), Chetac (aa), Clam (c),
Clare (rr), Crab (sss), Cranberry (aa), Devils (1) (rr), Devils (2) (ss),
Deer (rr), Duck (c), Dummy (rrr), Elizabeth (cc), Fish (sss), Found (ss).
Fowler (ss), Granite (ss), Grindstone (rr), Half Moon (s), Hillman (s).
Hooker (rr), Horseshoe (1) (ss), Horseshoe (2) (rrr), Island (cc), Jennie
(rr), Kawaguesaga (sss), Kitten (rrr), Kegonsa (aa), Lac du Flambeau (rr),
Lac la Belle (r), Laura (aa), Lindy (rr), Little Bass (2) (rr), Little Butter-
nut (rr), Little Rice (1) (cc), Long (1) (rr), Long (2) (a), Loon (rr), Lost
(aa), Lower Nemahbin (r), Marl (rr), Mendota (cc), Mercer (ss), Middle
McKenzie (cc), Mill (rr), Minocqua (rr), Monona (aa), Mud (1) (cc), Mud
(•3) (aa), Mudhen (rr), Nancy (c), Nicaboyne (r), No Mans (aa), North
Twin (cc), North Turtle (aa), Number One (ss), Oconomowoc (rr), Okauchee

dt) WISCONSIN PHYTOPLANKTON

(r), Otter (rr), Paddock (c), Palmer (SB), Pardee (rr), Pewaukee (ss),
Plum (ss), Pokegama (1) (c), Pokegama (2) (sss), Pokegama (3) (a), Pop-
lar (r), Prairie (s), Reserve (ss), Rainbow (r), Rice (1) (cc), Rock (a),
Rooney (aa), Round (1) (rrr), Round (2) (ss), Round (3) (ss), St. Croix
(cc), Sanford (r), Sand (1) (ss), Sand (2) (rr), Sand (3) (rr), Sand (4)
(rr), Silver (2) (c), iSishebogema (aa), South Turtle (sss), Upper Nashotah
(rr), Upper Nemahbin (rr), Upper Turtle (s), Wapagossett (cc), Waubesa
(cc), White Ash (rr), Whitefish (cc), White Sand (rrr), Wildcat (rrr), Win-
ncbago (cc),Wolf (rrr).

The radial fibrillar structure at the periphery of the gelatinous en-
velope is also found at times in the center of the colony. These radia-
tions have been compared by some to the gelatinous strands found in
Gomphosphaeria and the species transferred to that genus. I have
preferred to keep the alga in the genus where it was first described.
This alga is one of the important members of the Myxophyceae in the
formation of blooms but it is rarely found as the sole constituent of
any bloom. Bachmann's figures of the alga are quite characteristic.

GOMPHOSPHAERIA Kiitzing 1836.

Colonies microscopic, spherical to ellipsoid, embedded in a copious,
hyaline, solid, homogeneous, gelatinous envelope. Cells spherical
to pyriform, solitary or in pairs, generally lying some distance from
one another and forming a layer one cell in thickness towards the pe-
riphery of the colonial envelope. Central portion of colonial envelope
containing a denser core from which projections radiate to the base of
the cells. Individual sheaths of cells distinct or confluent with the
colonial envelope. Cell contents homogeneous, rarely granulose; grey
to light or bright blue-green.

Reproduction by alternate vegetative division of cells in three planes.

KEY TO THE SPECIES.

Cells spherical G. LACUSTBIS

Cells pyriform to cardioid G. APONINA

GOMPHOSPHAERIA LACUSTRIS Chodat. PI. 4, Fig. 5.

Bull. Herb. Boiss. 6: 180, figs. 1A-1G. 1898; W. & G. S. West, Trans. Roy. Irish
Acad. 33, Sec. B: 112, pi. 11, figs. 24-27. 1906.

Colonies small, generally spherical or subspherical, rarely reniform;
with a hyaline, homogeneous, gelatinous envelope. Cells spherical to
broadly ellipsoid, irregularly spaced to form a single layer one cell in
thickness beneath the periphery of the colonial envelope. Individual
cell sheaths confluent with colonial envelope. Central portion of col-
ony containing a core of denser radiating gelatinous strands that run

WISCONSIN PHYTOPLA.NKTON 37

to the base of the cells. Cell contents homogeneous; grey to pale or
bright blue-green, rose colored in rare instances. (Euplanktont).
Cells 1.5-2.5 /A broad, 1.5-4 p long. Colonies rarely over 40 /j. in diam.

Bear (1) (rr), Beaverdam (c), Big McKenzie (ss), Blake (sss), Cochrane
(r), Deer (rr), Diamond (r), Dunham (c), Fish (c), Half Moon (rr), Island
(rr), Kawaguesaga (r), Lac Court Oreilles (ss), Lindy (sss), Little Bass (2)
(rr), Long (1) (rr), Loon (rr), Mendota (s), Mercer (ss), Middle McKenzie
(ss), Mudhen (ss), Nicaboyne (r), North Twin (r), Pardee (rr), Plum (rr),
Pokegama (3) (rr), Sand (1) (r), Sand (2) (rr), Sand (4) (rr), Spirit (r),
Squirrel (sss), Star (sss), Wolf (r).

The colonies of this species resemble those of Coelosphaerium Kuetz-
ingianum in cell shape and arrangement but differ in the radiating
strands of gelatinous material running from the center of the colony
to the base of the cells. The gelatinous envelope is very delicate and
cells frequently break away leaving the central mass of gelatinous radi-
ations floating by itself.

GOMPHOSPHAERIA APONiNA Kiitzing. PI. 4, Figs. 2-3.

Decades 16: No. 151. 1836; G. S. West, Brit Freshw. Algae 349, fig. 163B-
1-904.

Colonies small, spherical to subspherical, with a fairly thick, hya-
line, homogeneous, gelatinous envelope. Cells pyriform to cuneate,
cardioid just before division; sparsely scattered and in a single layer
some distance beneath the periphery of the colonial envelope. Indi-
vidual sheaths of cells generally distinct, attached at the base to the
dense gelatinous strands radiating from the center of the colony. Cell
contents homogeneous or finely granulose; without pseudovacuoles ;
generally a bright blue-green. (Tychoplanktont).

Cells 4-5 n wide at the greatest breadth, 8-15 //. long. Diam. colonies
50-90 /..

Beaverdam (sss), Big McKenzie (rrr), Browns (rr), Center (rr), Eagle
(rr), Elizabeth (rr), Hillman (rr), Kegonsa (rrr), Lower Nemahbin (rr),
Mendota (rr), Mary (rr), Monona (rrr), Mudhen (rr), North Turtle (rrr),
Otter (rrr), Pewaukee (rr), Pine (1) (rrr), Plum (rrr). Silver (2) (rr), Sil-
ver (3) (rr), South Turtle (rr), Waubesa (r).

var. CORDIFORMIS Wolle. PI. 4, Fig. 4.
Bull. Torr. Bot. Cl. 9: 25, pi. 13, fig. 11. 1882.

Cells considerably larger than in the typical form and markedly
heart shaped instead of pyriform. Individual sheaths of cells conspicu-
ous. Cell contents bright blue-green. (Tychoplanktont).

Greatest breadth of cells 6-13 p, ; length 9-20 p..

Bloom (rrr).

38 WISCONSIN PHYTOPLANKTON

The cells of the Wisconsin individuals are somewhat longer than
Wolle found them, his measurements for the length of the cell varying
from 9-16 u,.

MICROCYSTIS Kiitzing 1833.

Colonies free-floating; spherical, elongate, irregular, or perforate to
form reticulate or clathrate masses of microscopic or macroscopic size.
Frequently occurring in sufficient quantities to give the water a verdi-
gris-green color. Envelope of colonies generally copious, delicate to
firm. Cells small, spherical, distributed in a solid mass throughout the
colony and densely aggregated. Individual cell sheath confluent with
colonial envelope. Cell contents homogeneous or with numerous pseudo-
vacuoles ; light to dark blue-green, olive-green, or rose colored.

Reproduction by vegetative division of cells in three directions.

Certain species of the genus occur in prodigious quantities and cause
the familiar blooming of lakes. These species contain pseudovacuoles,
while species without pseudovacuoles rarely occur in quantity.

KEY TO THE SPECIES.

Cells with numerous pseudovacuoles.

Several colonies enclosed by the same envelope .......... M. ICHTHYOBLABE

Colonies not differentiated into several within the same envelope.

Colony entire, not perforate .......................... M. FLOS-AQUAE

Colony saccate and perforate ......................... M. AERUGINOSA

Cells without pseudovacuoles.

Diameter of cells less than 1.5 /* .............................. M. INCEBTA

Diameter of cells 2-3 //, ...................................... M. PurmiA

MICROCYSTIS ICHTHYOBLABE Kiitzing.

Phycol. generalis 170. 1843.

Polycystis ichthyoblabe Kiitzing, Tabulae Phycol. 1: 7, pi. 8. 1845.

Colonies spherical or irregular, fragmented into several distinct sub-
colonies, each Avith its own gelatinous envelope, and with the sub-col-
onies enclosed by a common gelatinous envelope. Cells spherical, close
together. Individual cell sheaths confluent with colonial envelope. Cell
contents pale to bright blue-green. Generally containing numerous
pseudovacuoles. (Facultative Planktont).

Diam. cells 2-4 ju,.

Catfish (rr), Clear (rr), Kawaguesaga (ss), Minocqua (r).

WISCONSIN PHYTOPLANETON 39

MICROCYSTIS FLOS-AQUAE (Wittrock) Kii'chner. PI. 5, Fig. 1.
in Engler & Prantl, D. nat. Pflanzenfam. 1 (Abt. la) : 56, fig. 49N. 1900.

Colonies spherical to ovoid, rarely elongate; frequently reaching a
macroscopic size. Cells compactly and evenly distributed within a very
delicate, hyaline, homogeneous, gelatinous envelope. Margins of colony
not sharply defined. Cell contents rarely homogeneous and grey to
pale blue-green; usually with pseudovacuoles and reddish in color.
Plant mass yellowish to verdigris-green. (Euplanktont).

Diam. cells 3.5-6.5 /*.

Bear (2) (rr), Big St. Germain (rr), Birch (1) (c), Birch Island (sss),
Browns (cc), Catfish (ss), Center (ss), Cochrane (sss), Duck (ss), Dunham
(rr), Fishtrap (rr), Pound (sss), Fowler (rr), High (rr), Horseshoe (1) (rr),
Kegonsa (cc), Loveless (r), Lower Nashotah (rr), Lower Nemahbin (r),
Mendota (aa), Mercer (rrr), Monona (aa), Mud (3) (cc), Nagawicka (rr),
No Mans (r), North Turtle (ss), Oconomowoc (ss), Paddock (ss), Palmer (ss),
Par dee (ss), Plum (ss), Pokegama (1) (ss), Rainbow (r), Rock (s), Rose
(ss), Sand (3) (r), .Shell (rr), Sishebogema (ss), South Turtle (ss), Squirrel
(rr), Star (ss), Tamarack (ss), Tenderfoot (rr), Upper Nashotah (rrr), Wapa-
gossett (ss), Waubesa (ss), Whitefish (ss), Winnebago (cc).

MICROCYSTIS AERUGINOSA Kiitzing. PL 5, Figs. 2-3.

Tabulae Fhycol. 1 : 6, pi. 8. 1845.

Clathrocystis aeruginosa (Kiitzing) Henfrey, Trans. Micr. Soc. London N. S.
4: 53, pZ. 4, figs. 28-36. 1856 (in Quart. Jour. Micr. Sci. 4: 1856): Bachmann,
Arch. f. Hydrobiol. u. Planktonkde. 3: 61, figs. IV'-IV. 1908.

Colonies spherical to subspherical when young, later becoming saccate
and ultimately reticulate and clathrate. Gelatinous envelope of colony
homogeneous, hyaline, and indistinct. Colonies frequently occurring
in sufficient quantity to color water a bright green. Cells spherical to
subspherical, evenly distributed throughout the colony and close to-
gether. Cell contents rarely homogeneous and grey to pale or bright
blue-green; usually with numerous pseudovacuoles and reddish. (Eu-
planktont).

Diam. cells 3-4 p.

Balsam (ss), Bear (3) (rr), Big Butternut (ss), Bloom (ccc), Bone (ss),
Browns (cc), Center (rr), Clam (r), Crooked (rrr), Delavan (sss), Desmoines
(ss), Devils (2) (rr), Duck (rr), Dutchmans (rrr), Eagle (ccc), Elizabeth
(cc), Fish (ss), Fowler (rr), Grassy (ss), Grindstone (rr), Half Moon (ss),
Hooker (ss), Horseshoe (1) (rr), Kawaguesaga (rr), Kegonsa (a), Kimball
(ss), Lac du Flambeau (rr), Lac la Belle (rr), Lake of the Woods (r), Little
Bass (2) (sss), Little Butternut (cc), Little Crooked (ss), Little Wood (ss),
Loveless (ss), Mendota (a), Meronk (ss), Mill (sss), Monona (cc), Mud (2)
(r), Mudhen (ss), Nancy (ss), Nicaboyne (ss), North Turtle (ss), North
Twin (cc), Oconomowoc (rrr), Old Taylors (r), Otter (rr), Owen (rrr), Par-
dee (ss), Pewaukee (ss), Pokegama (2) (rr), Pokegama (3) (ss), Prairie

40 WISCONSIN PHYTOPLANKTON

(sss), Rice (1) (rr), Rooney (r), Sand (1) (ss), Sand (4) (IT), Shell (rr),
Silver (2) (ss), Travis (rr), Upper Turtle (ss), Waubesa (cc), White Ash
(sg), Wildcat (ss), Wolf (rr).

var. MAJOR (Wittrock) G. M. Smith. PI. 4, Fig. 6.
Trans. Wls. Acad. Sci., Arts, & Lett. 18': 535. 1916.

Mature colonies elongate; irregular, saccate, or clathrate. Colonial
envelope much firmer than in typical form and with larger cells. (Eu-
planktont).

Diam. cells 5.5-6.5 /*.

Center (rr), Mendota (ss), Nancy (sss), St. Croix (rr), Vermilion (cc).

MICROCYSTIS INCERTA Lemmermann. PI. 5, Fig. 4.

Abh. Naturw. Ver. Bremen 17: 342. 1903; Kryptogamenfl. d. Mark Branden-
burg 3; Algen 1: 76, 44, fig. 12. 1907.

Colonies spherical or somewhat elongate, enclosed by a hyaline, homo-
geneous, and very delicate gelatinous envelope. Cells small, very close
together but equidistant from one another. Cell contents homogeneous,
without pseudovacuoles ; grey to pale blue-green in color. (Faculta-
tive Planktont).

Diam. cells 1-2 p.

Camp (rr), Chetek (r), Hooker (s), Prairie (r), Whitefish (rr), Winne-
bago (c).

The cells of this species are very similar in appearance to those found
in Aphanocapsa elachista and A. delicatissima but their compact ar-
rangement shows that the alga is a Microcystis and not an Aphanocapsa.

MICROCYSTIS PULVERA (Wood) Migula.

in Thome", Flora v. Deutschl., Deutsch.-Osterr. u. d. Schw. 6, Kryptogamen 2,
Algen 1: 36. 1907.

Anacystis pulverus Wood. Wolle, Freshw. Algae of U. S. 329, pi. 210, fig. 25.
1887.

Colonies spherical or elongate, with a very delicate, hyaline, gela-
tinous envelope. Cells spherical, very closely crowded together and
forming a solid mass. Cell contents homogeneous, without pseudovacu-
oles ; grey, pale olive-green, or blue-green in color. (Facultative Plank-
tont) .

Diam. cells 2-3 p.

Browns (rr), Mill (rrr), Pardee (ss), Sunday (r), Winnebago (sss).

Since the specific difference between this and the foregoing species
is mainly one of cell size it might be better to consider M. incerta a
variety of M. pulvera.

WISCONSIN PHYTOPLANKTON 41

APHANOCAPSA Nageli 1849.

Cells united to form spherical, ovoid, or amorphous colonies of micro-
scopic or macroscopic size. Colonies, hyaline, yellow, brown, or blue-
green in color. Cells spherical, equally distributed throughout the
colony but always some distance from one another; generally solitary,
rarely in clusters. Individual sheaths of cells confluent with the homo-
geneous, hyaline or colored, colonial envelope. Cell contents homogene-
ous ; usually pale to bright blue-green or grey in color.

Reproduction by vegetative division of cells in three directions.

KEY TO THE SPECIES.

Cells growing within gelatinous envelope of other algae A. ENDOPHYTICA

Cells forming free-floating or sessile colonies.
Cell contents grey to pale blue-green.

Diameter of cells 3.5-4.5 M A. PULCHBA

Diameter of cells less than 3 /*.

Cell diameter not exceeding 1 /j. A. DELICATISSIMA.

Cell diameter 1.5-2.5 M A. ELACHISTA

Cell contents brightly colored, generally blue-green.

Diameter of cells 3.5-5 n A. GREVILLEI

Diameter of cells 5-6 /j. A. RIVULABIS

APHANOCAPSA DELICATISSIMA W. & G. S. West. PI. 2, Fig. 7.
Jour. Linn. Soc. Bot. 40: 431, pi. 19, figs. 2-3. 1912.

Colonies small, spherical, ovoid or irregular, free-floating. Colonial
envelope gelatinous, homogeneous, hyaline or ochraceous. Cells spheri-
cal, very small, more or less remote from one another. Cell contents
homogeneous, grey to pale blue-green. (Euplanktont).

Cells .5-.T5 /A in diam. ; colonies 15-30 p. broad, 15-50 /* lonsr.

Big Butternut (r), Chain (r), Little Butternut (ss), Loveless (ss), Mendota
(s), Poor Farm (r).

The cells of this species are smaller than many bacteria and during
the first two year's study of the plankton flora these small colonies were
considered bacteria and not recorded so that the record for distribution
is far from complete. When the colonies are of any considerable size
the mass of cells has a decided blue-green color so that the organism
must be called a blue-green bacterium or a blue-green alga of bacterial
size. The latter view seems to be the more logical. It is very probable
that the bacteria have been derived from the blue-green algae and the
Wests' discovery of blue-green algae of bacterial size is very suggestive.

42 WISCONSIN PHYTOPLANKTON

t

APHANOCAPSA ELACHISTA var. CONFEKTA W. & G. S. West. PI. 2, Fig. 8.
Jour. Linn. Soc. Bot. 40: 432, pi. 19, fig. 1. 1912.

Colonies small, spherical, ovoid, or irregular; with the cells enclosed
by a gelatinous, homogeneous, hyaline or ochraceous envelope. Indi-
vidual sheaths of cells confluent with colonial envelope. Cells spheri-
cal, fairly close together. Cell contents homogeneous, grey to pale
blue-green. (Euplanktont).

Diana, cells 1.6-2.0 /*. Colonies up to 75 ^ broad and 100 p long.

Birch Island (rr), Crawling Stone (rrr), Deer (ss), Lindy (r), Nancy (r),
Pine Tree (ss), Silver (2) (rr).

var. planctonica var. nov. PI. 3, Fig. 3.

Cells spherical, some distance from one another. Sheath enclosing
colony always hyaline. Contents of cells pale grey. (Euplanktont).
Diam. cells 2-3 p.

Bear (1) (s), Bear Trap (rr), Poplar (ss), Round (3) (rr), Sand (1) (r).

Differing from the typical form in the larger cell size and grey color
of the cell contents.

Aphanocapsa endophytica sp. nov. PI. 2, Fig. 10.

Colonies endophytic within the gelatinous sheath of Microcystis col-
onies and with their envelopes confluent with the envelope of the host
colony. Cells spherical, equidistant from one another or in small
clumps. Cell contents homogeneous, grey to bright blue-green. (Eu-
planktont).

Diam. cells 2 /i.

Poor Farm (ss).

The occurrence of bacteria in the gelatinous envelope of colonial
Myxophyceae is a familiar phenomenon to the limnologist. The blue-
green color of the cells endophytic within the envelopes of Microcystis
colonies in Poor Farm Lake precludes their recognition as bacteria.
(See G. S. West's remarks concerning a similar endophytic Aphano-
thece in Jour. Linn. Soc. Bot. 40: 432. 1912).

APHANOCAPSA PULCHRA (Kiitzing) Rabenhorst. PI. 2, Fig. 9.
Flora Eur. Algarum 2: 49. 1865.

Colonies macroscopic or microscopic, free-floating or sessile, generally
spherical to ovoid when found in the plankton. Sheath of colony gela-
tinous, firm, hyaline, homogeneous; with the cells some distance from

WISCONSIN PHTTOPLANKTON 43

one another. Individual cell sheaths confluent with the colonial en-
velope. Cell contents homogeneous, grey to pale blue-green. (Tycho-
planktont).

Diam. cells 3.5-4.5 /*.

Beaver (r), Beaverdam (sss), Harris (rrr), Lac Court Oreilles (ss), Win-
nebago (rr).

APHANOCAPSA GREVILLEI (Hassall) Rabenhorst. PI. 3, Fig. 1.

Flora Eur. Algarum 2: 50. 1865; G. S. West, Brit. Freshw. Algae, 351, fig.
165A. 1904.

Colonies free-floating or sessile ; spherical to ellipsoid when free-float-
ing, dirty green in color. Cells spherical, solitary or in pairs and some-
what crowded. Cell contents homogeneous or finely granulose, bright
blue-green in color. (Facultative Planktont).

Diam. cells 3.5-5 p..

Beaverdam (rr), Birch (ss), Camp (ss), Chetac (sss), Muskallonge (rr),
Rice (1) (rr), Silver (1) (rrr), Whitefish (ss).

APHANOCAPSA RIVULARIS (Carm.) Rabenhorst. PI. 3, Fig. 2.

Flora Eur. Algarum 2: 49. 1865; Cooke, Brit. Freshw. Algae 210, pi. 86, fig. 2.
1884.

Colonies free-floating or sessile ; spherical, tubular, or irregular in
shape. Cells spherical, solitary or in pairs and some distance from one
another Avithin the colony. Individual sheaths of cells confluent with
the hyaline, homogeneous, colonial envelope. Cell contents homogene-
ous or finely granulose; bright blue-green in color. (Tychoplanktont).

Diam. cells 5-6 //..

Star (rrr).

APHANOTHECE Nageli 1849.

Colonies free-floating, sessile, or endophytic; spherical or expanded
into amorphous masses and enclosed by a firm, copious, homogeneous,
hyaline or colored envelope. Cells oblong to cylindrical, with rounded
ends. Cells forming a solid mass distributed throughout the colonial
envelope but lying some distance from one another. Individual cell
sheaths indistinct, confluent with the colonial envelope. Cell contents
homogeneous or finely granulose, never with pseudovacuoles ; grey, light
to bright blue-green, or olive-green in color.

Reproduction by vegetative division of cells in three planes, but with
cell divisions always taking place at right angles to the long axes of
cells.

44 WISCONSIN PHYTOPLANKTON

KEY TO THE SPECIES.

Colonies endophytic in gelatinous envelope of other algae. .

A. NiDtrLANS v. ENDOPHTTICA

Colonies not endophytic.

Cell contents grey to pale blue-green, never bright blue-green.

Colonies ovoid to spherical, never perforate A. NIDULANS

Colonies reticulate to clathrate A. CLATHBATA

Cell contents bright blue-green.

Cells less than 5 M broad A. STAGNINA

Cells more than 5 M broad A. PBASINA

APHANOTHECE CLATHRATA W. & G. S. West. PL 6, Fig. 3.
Trans. Roy. Irish Acad. 32, Sec. B: 111, pi. 10, figs. 9-11. 1906.

Colonies microscopic ; free-floating ; elongate and irregular in shape,
usually perforate and reticulate. Gelatinous colonial envelope hyaline
and homogeneous. Cells very small, bacilliform, straight or curved,
embedded in a solid mass in the colonial envelope. Cell contents homo-
geneous, grey to light blue-green. (Euplanktont).

Cells 0.6-1.0 p. broad, 3.5-4.5 p. long.

Lindy (r), Little Crooked (sss), Nancy (ss), Pokegama (1) (r), Poor
Farm (rr), iSand (1) (ss), Wolf (ss).

APHANOTHECE NIDULANS P. Richter. PI. 6, Fig. 1.

Bot. Not. 1884: 128. 1884.

Colonies spherical, ovoid, or ' ' nest-shaped ' ' ; enclosed by a homogene-
ous, hyaline, gelatinous envelope. Cells broadly cylindrical, straight
or curved, of small size and fairly close together. Individual sheaths
of cells confluent with the colonial envelope. Cell contents homogene-
ous, grey to light blue-green. (Facultative Planktont).

Cells 1.0-1.5 p. broad, up to 3.5 p. long.

Beaver (2) (ss), Deer (ss), Lower McKenzie (sss), Pokegama (sss), Ten-
derfoot (r).

Certain species of this genus resemble bacterial colonies in much the
same manner as the minute-celled species of Aphanocapsa. Here again
the color of the cell contents is good evidence of the algal nature of the
organism.

var. ENDOPHYTICA W. & G. S. West. PI. 5, Fig. 6.
Jour. Linn. Soc. Bot. 40: 432, pi. 19, fig. 14. 1912.

Cells embedded in gelatinous envelope of other colonial Myxophy-
ceae. Gelatinous envelope of colony confluent with envelope of host

WISCONSIN PHYTOPLANKTON 45

colony. Cells narrow, at least twice as long as they are broad. Cell
contents homogeneous; generally light blue-green, rarely grey. (Eu-
planktont).

Cells 0.8-1.5 n broad, 2.5-4.5 p. long.

Endophytic in sheaths of Coelospliaerium Kuetzingianum and Micro-
Cystis aeruginosa.

Birch Island (r), Chetac (ss), Round (3) (rr).

APHANOTHECE PRASINA A. Braun. PI. 5, Fig. 5.

In Rabenhorst, Flora Eur. Algarum 2: 65. 1865; Cooke, Brit. Freshw. Algae,
218, pi. 88, figs. 3*-3i>. 1884.

Colonies spherical to cylindrical, reaching a diameter of 3-4 cm. un-
der favorable conditions; bright green in color. Cells evenly dis-
tributed throughout the colony, broadly cylindrical and with rounded
ends. Individual cell sheaths confluent with the colonial envelope.
Cell contents homogeneous, bright blue-green. (Tychoplanktont).

Cells 5-6.5 p broad, 7.7-11 /x long.

Beaverdam (r), Nancy (rr), Pokegama (1) (rrr).

The determination of this and the following species is open to ques-
tion since specific differences in these species are based in part upon
the macroscopic appearance of the colony when growing attached to
the substratum. The determination of plankton species is from imma-
ture colonies and must rest upon cell shape, size, and color.

APHANOTHECE STAGNINA (Sprengel) A. Braun. PI. 6, Fig. 2.

in Rabenhorst, Algen No. 1572; Cooke, Brit. Freshw. Algae 219, pi. 88,
fig. 4. 1884.

Colony spherical, ellipsoidal, or cylindrical; generally macroscopic,
0.5-20 mm in diameter, pale verdigris-green. Cells broadly cylindrical,
their length never more than iy2 times their breadth. Individual
sheaths of cells confluent with the hyaline, homogeneous, gelatinous,
colonial envelope. Cell contents homogeneous; pale to bright blue-
green. ( Tychoplanktont) .

Cells 3-5 fj. broad ; 5-8 /* long.

Lake of the Woods (rr), Whitefish (rr).

GLOEOTHECE Nageli 1849.

Colonies free-floating or sessile, of comparatively few cells enclosed
by a hyaline or variously colored, homogeneous, gelatinous envelope.
Individual sheaths of cells prominent, homogeneous or slightly lamel-

46 WISCONSIN PHYTOPLANKTON

lated, sometimes 2-8 cells enclosed by a single sheath. Cells elongate
to broadly cylindrical, with rounded ends and irregularly distributed
throughout the colonial envelope or with their longer axes pointing in
the same general direction. Cell contents homogeneous or finely granu-
lose; grey, pale to bright blue-green, or olive green in color.

Eeproduction by vegetative division of cells at right angles to their
long axes.

G-LOEOTHECE LiNEARis Nageli. PI. 6, Fig. 5.
Gatt. einz. Algen 58, pi. 1, fig. G2. 1849.

Colonies small; dull yellow to flesh color or dirty olive-green; en-
closed by a broad, hyaline, homogeneous, gelatinous envelope. Cells
elongate-cylindrical, straight or arcuate, with rounded ends. Sheaths
containing one cell only, broad, hyaline, having the same general out-
line as the cell. Cell contents homogeneous ; pale to bright blue-green.
(Tychoplanktont) .

Cells (without sheath) 1.3-2.5 p. broad, 10.5-18 p. long; (with sheath)
4-6 p. broad, 13-22 p. long.

Harris (r), Muskallonge (rr).

var. composita var. nov. PI. 6, Fig. 6.

Cells shorter and 2-8 enclosed by a single, broad, firm, homogeneous
sheath. Individual sheaths of single cells or groups of cells not con-
fluent with the colonial envelope. (Tychoplanktont).

Cells (without sheath) 3.0-3.5 p. broad, 4-8 p. long; sheaths 10-12
p. broad, 20-35 /*. long.

Deer (rrr).

RHABDODERMA Schmidle and Lauterborn. 1900.

Colonies free-floating, small, of comparatively few cells enclosed by a
hyaline, homogeneous, gelatinous envelope. Cells cylindrical, witk
rounded apices, straight or arcuate; with their long axes pointing in
the same general direction. Individual sheaths of cells confluent with
colonial envelope. Cell contents homogeneous; grey to bright blue-
green in color.

Reproduction by vegetative division of cells, the divisions taking
place at right angles to the long axes of the cells.

WISCONSIN PHYTOPLANKTON 47

EHABDODERMA LINEAEE Schmidle and Lauterborn. PI. 6, Fig. 4.
Ber. d. D. Bot. Ges. 18: 148, pi. 6, figs. 8-11. 1900.

Specific characters as those of the genus. (Euplanktont).
Cells 2-3 IL broad, 6-12 p. long.

Sand (2) (rrr), Whitefish (rr).

This genus is closely related to Gloeothece, the chief difference being
a lack of individual sheaths around the cells.

DACTYLOCOCCOPSIS Hansgirg 1888.

Colonies microscopic, free-floating or lying among other algae; em-
bedded in a copious, hyaline, homogeneous, acicular to fusiform, gela-
tinous envelope. Cells elongate, acicular and with pointed ends;
straight arcuate, sigmoid, or spirally twisted around one another. In-
dividual cell sheaths confluent with colonial envelope. Cell contents
homogeneous or with the color bearing area localized in a definite part
of the cell ; grey to bright blue-green in color.

Reproduction by vegetative division of cells at right angles to their
long axes.

KEY TO THE SPECIES.

Length of cells never more than sixteen times the breadth,

cells frequently bent D. RAPHIDIOIDKS

Length of cells at least twenty times the breadth, cells al-
ways straight D. ACICULABIS

DACTYLOCOCCOPSIS RHAPHIDIOIDES Hansgirg. PI. 6, Fig. 7.

Prodr. d. Algenfl. v. Bohmen 139, fig. 49A. 1892; Lemmermann, Kryptogamenfl.
d. Mark Brandenburg 3, Algen 1: 50. 1907.

Colonies containing 2-8 or more cells. Cells fusiform ; straight, arcu-
ate or sigmoid ; frequently in pairs with one end rounded and the other
pointed. Colonies enclosed by a copious, hyaline, homogeneous en-
velope. Cell contents homogeneous, pale blue-green. (Facultative
Planktont).

Cells 1-3 /A broad, 5-25 p long.

Deer (sss), Long (2) (rrr), Mercer (rr), Reserve (rr), Rice (1) (rr).

Hansgirg gives eight as the maximal number of cells found in the
colony but I have observed colonies in which there are as many as a

48 WISCONSIN PETTOPLANKTON

hundred cells. These cells are also proportionally longer than he states
and may be, in extreme cases, sixteen times as long as they are broad.
In this respect they follow the cell dimensions delimited by Lemmer-
raann.

DACTYLOCOCCOPSIS ACICULAEIS Lemmermann. PI. 6, Figs. 8-10.

Ber. d. D. Bot. Ges. 18: 309. 1900; Kryptogamenfl. d. Mark Brandenburg 3,
Algen 1: 51, 44, fig. 5. 1907.

Cells solitary or in colonies enclosed by a wide, hyaline, homogeneous,
gelatinous sheath. Cells elongate, acicular, with poles attenuated to
fine points; straight or slightly arcuate. Cell contents homogeneous
and pale blue-green ; or with color bearing region restricted to one side
of cell. (Euplanktont).

Cells 2-2.5 (i broad, 55-80 p. long.

Browns (cc).

The localization of the color bearing portion at one side of the cell is
quite abnormal for a member of the Myxophyceae, but, as I have stated
elsewhere (Trans. Wis. Acad. Sci., Arts, & Lett. 191: 620. 1918) not-
withstanding this fact the alga belongs to the Myxophyceae.

Order HORMOGONEALES.

Cells always in filaments that generally contain a number of cells.
Filaments simple or branched; solitary or united to form definitely or
indefinitely shaped aggregates. Free-floating, sessile, epiphytic, or en-
dophytic. Cells serially arranged to form trichomes, which when en-
closed by a sheath are known as filaments. Trichomes either the same
thickness throughout, attenuated towards both extremities, or attenu-
ated from base to apex ; straight, arcuate, spirally or irregularly twisted.
Sheaths of filaments tough and leathery; or gelatinous, homogeneous
to lamellated, hyaline to variously colored, and distinct or confluent
with the colonial envelope. Cell shape various. Cell contents homo-
geneous, or with numerous pseudovacuoles ; grey, light to dark blue-
green, olive-green, reddish-green, ochraceous, orange, violet, or black
in color.

Reproduction, aside from vegetative cell division, by hormogones and
resting spores.

WISCONSIN PHYTOPLANKTON 49

KEY TO THE FAMILIES.

Trichomes without heterocysts* OSCILLATOBIACEAE

Trichomes with heterocysts.

Trichomes not attenuated NOSTOCACEAE

Trichomes attenuated to a hair-like point RIVULARIACEAE

Family OSCILLATORIACEAE.

Trichomes free-floating, sessile, epiphytic, or endophytic; of one or
mere cells forming simple or branched filaments with one or more tri-
chomes within a single sheath. Sheaths of various forms; copious,
gelatinous, hyaline or colored, homogeneous to lamellated; firm, nar-
row and homogeneous or lamellated; or entirely lacking. Filaments
straight or spirally twisted. Cells disciform, cylindrical, or barrel-
shaped. Apical cell of trichomes frequently conical and capitate.
Heterocysts never present in the trichomes. Cell contents homogene-
ous, granulose, or with pseudovacuoles ; variously colored.

Reproduction by vegetative division of cells and the formation of
hormogones.

KEY TO THE GENERA.

Trichomes solitary or in flocculent, readily dissociating masses.

Trichomes containing but one cell SPIRUIJNA

Trichomes containing more than one cell.

Sheaths of filaments firm, generally projecting beyond

the trichome LTNGBYA

Sheaths delicate or lacking, not projecting beyond

trichome OSCILLATORIA

Trichomes laterally united to form free-floating bundles which

do not dissociate readily TEICHODESMIUM

SPIRULINA Turpin 1827.

Trichome consisting of a single, elongate, cylindrical cell that is not
attenuated but with rounded ends. Filaments without sheaths and
twisted to form loose or compact regular spirals. Cell contents homo-
geneous or granulose ; light to dark blue-green in color.

Reproduction by vegetative division of cells at right angles to the
long axis. No hormogone formation possible.

•Cells commonly larger than the vegetative cells and with heavy walls that
have a conspicuous nodule at each pole. Cell contents a homogeneous, pellucid,
Bon-cytoplasmic substance.

50 WISCONSIN PHYTOPLANKTON

KEY TO THE SPECIES.

Turns of spirals not over 5 M in diameter S. MAJOB

Turns of spirals over 10 n in diameter S. PBIITCEPS

SPIRULINA MAJOR Kiitzing. PI. 7, Fig. 1.

Phycol. generalis 183. 1843; Gomont, Ann. Sci. Nat. 7 Ser., Dot. 16: 251, pi. 7,
fig. 29. 1892.

Filaments free-floating and solitary, or forming a greenish, scum.
Trichomes in a more or less loose spiral that is straight or bent. Cell
contents homogeneous ; bright blue-green. Sheath of filament lacking.
( Tychoplanktont) .

Triehomes 1.2-1.7 /x in diameter. Spirals 2.5-4 /* broad, 2.7-5
fj. between turns.

White Ash (rrr).

SPIRULINA PRINCEPS (W. & G. S. West) G. S. West emend. PI. 7, Fig. 2.

Jour. Linn. Soc. Bot. 38: 179, pi. 9, fig. 5. 1907; W. & G. S. West, Trans. Linn.
Soc. Bot. 2 -Ser., Bot. 6: 205. 1902.

Trichomes solitary, in loose spirals that may be straight or curved.
Ends of trichomes blunt or rounded. Cell contents homogeneous or
with a few scattered granules; bright blue-green. (Tychoplanktont).

Trichomes 3-5 /* broad. Spirals 8.8-16 ^ broad, 9.5-12 p between

turns.

Poor Farm (rrr).

OSCILLATORIA Vaueher 1803.

Trichomes possessing a peculiar power of spontaneous movement of
an oscillating, rolling, or gliding type; free-floating; solitary or in
flocculent masses ; sometimes forming strata in moist places. Trichomes
unbranched, cylindrical, entirely without or with barely perceptible
sheaths. Ends of trichomes straight, slightly attenuated, but never at-
tenuated to a point. Terminal cells rounded or calyptrate. Cell shape
cylindrical to disciform. Cell contents usually homogeneous or granu-
lose, rarely with pseudovacuoles. Color of cells variable.

Reproduction by hormogones.

WISCONSIN PHJTOPLANKTON 51

KEY TO THE SPECIES.

Apex of trichome gradually tapering O. PBOLIFICA

Apex of trichome not tapering O. TENUIS

OSCILLATORIA PROLIFICA (Greville) Gomont. PI. 7, Figs. S-5.

Ann. Scl. Nat. 7 'Ser. Hot. 16: 205, pi. 6, fig. 8. 1892; Olive, Trans. Wis. Acad.
Scl., Arts, & Lett. 151: 124-134. 1905; Hyams and Richards, Technology Quart.
14: 302-310, figs. 1-8. 1901.

Filaments rarely solitary, generally irregularly matted to form free-
floating flocculent masses. Plant masses blood-red to dirty purple, be-
coming lilac when dried. Trichomes straight, elongate, not constricted
at cross walls of cells, and slightly tapered at apex with the terminal
cell of mature trichomes obtuse-capitate. Cells cylindrical, slightly
longer than they are broad. Cell contents with numerous reddish
pseudovacuoles, sometimes with rows of granules at the cross walls.
(Euplanktont).

Cells 2.2-5 /x, broad, 4^6 /*. long.

Geneva (aa), Pine (1) (aa).

This species is closely related to 0. riibescens D. C., but if Gomont 's
monograph of the Oscillatoriaceae must be taken as the starting point
for nomenclature of the group the two are distinct. Both species are
peculiar in that they produce blooms in lakes at a time when the water
is very cold or covered with ice. The masses of filaments do not have
the usual yellowish-green color but are blood red to dirty purple and
the phenomenon is spoken of in Europe as "bloody" or "Burgundy"
bloom.

Olive has described the occurrence of such a bloom in Pine lake of
this state and discussed the literature of the subject. The alga also
appeared in profusion in Lake Geneva this (1918) spring at the time
when the ice was beginning to disappear. It was not frozen in the ice
but grew luxuriantly in the water below the ice and gave a deep red-
dish color that was especially noticeable in the cracks between the ice.
The alga had not been noted in the lake before this time and its sporadic
appearance is quite like the sporadic appearance of 0. riibescens in the
Swiss lakes. The excessive growth of 0. prolifica is not wholly corre-
lated with cold water since it has remained present throughout the
summer, but not in such quantities as early in the spring. This abund-
ant growth of the alga in the summer has also been noted in a Massa-
chusetts lake by Hyams and Richards and furnishes a physiological as
well as a morphological distinction between 0. prolifica and 0. riibes-

52 WISCONSIN PHYTOPLANKTON

OSCILLATORIA TENUIS C. A. Agardh. PI. 7, Fig. 6.

Algarum decades 2: 25. 1813; Gomont, Ann. Sci. Nat. 7 S6r. Bot. 16: 220,
pi. 7, figs. 2-3. 1892.

Filaments solitary or in floccose masses that are pale blue-green in
color. Trichomes straight, slightly constricted at the cross walls. Termi-
nal cells the same diameter as those in the median portion of the trich-
ome, straight or curved; apical cells rounded but not capitate. Cell
shape disciform. Cell contents homogeneous except for a row of gran-
ules along the cross walls. (Tychoplanktont).

Cells 4-10 fi broad, 2.6-5 M long.

Monona (rr).

var. TERGESTINA (Kiitzing) Rabenhorst. PI. 7, Figs. 7-8.

Flora Eur. Algarum 2: 102. 1865.

Trichomes narrower than the foregoing. (Tychoplanktont).
Cells 4—6 /A broad.
Geneva (ss).

LYNGBYA C. A. Agardh. 1824.

Filaments solitary or interwoven to form floccose masses; free-float-
ing or in an expanded stratum. Sheaths of filaments narrow, firm,
hyaline or colored, homogeneous or lamellated, generally projecting
for some distance beyond the trichome. Filaments unbranched, cylin-
drical ; straight, flexed, or twisted into regular spirals. Trichomes gen-
erally the same thickness throughout, rarely slightly attenuated at the
apices ; sometimes constricted at the cross walls. Apical cell with distal
end rounded or slightly capitate. Cell contents homogeneous, granu-
lose, or with numerous pseudovacuoles ; grey, pale to bright blue-green
or variously colored.

Reproduction by the formation of hormogones.

KEY TO THE SPECIES.

Filaments not over 4 n in thickness, with pale blue-green to grey cell contents.

Filaments straight L. LIMNOTICA

Filaments in regularly coiled spirals L. COXTOBTA

Filaments over 10 M in diameter, contents deeply colored L. BIRGEI

LYNGBYA LJMNETICA Lemmermann. PI. 7, Figs. 9-11.

Bot. Cent. 76: 154. 1898; Kryptogamenfl. d. Mark Brandenburg 3, Algen 1:
135, 102, fig. 8. 1907.

Filaments free-floating, generally solitary ; straight or slightly flexed.
Trichomes not constricted at the cross walls. Apical cells the same

WISCONSIN PHYTOPLANKTON 53

thickness as the other cells, with distal end rounded but not capitate.
Sheaths firm, hyaline, very narrow, extending for some distance beyond
the end of the trichome. Cells cylindrical, at least twice as long as
broad. Cell contents homogeneous; generally grey, rarely blue-green
in color. (Euplanktont).

Cells 1-1.5 p, broad, 3-8 p. long.

Bear (1) (c), Geneva (ss), Soft (rr), Upper Nashotah (rrr).

The length of the individual cells of Wisconsin specimens exceeds
that given by Lemmermann but it is very probable that I am dealing
with the same species that he names L. limnetica. Several plankton
"species" have been described which are closely related and it is very
probable that future investigations will show that all of these straight,
very narrow, colorless "species" should be included under one collect-
ive specific name.

LYNGBYA CONTORTA Lemmermann. PL 7, Figs. 12-13.

Forschungsbr. a. d. Biol. Stat. zu Plon 6: 202, pi. 5, figs. 10-13. 1898; G. S.
West Jour, of Bot. 47: 246, pi. 498, figs. 5A-5B. 1909.

Filaments free-floating, solitary; occasionally straight, generally
twisted to form regular, loose or compact spirals or helices. Sheaths
firm, very thin, extending for some distance beyond the trichomes. Trich-
omes the same thickness throughout, not constricted at the cross walls,
apical cells rounded but not capitate at the distal ends. Cell contents
homogeneous, grey to pale blue-green. (Euplanktont).

Cells 1.5-2 p broad, 3-6 /* long. Spirals 15-20 /*. broad, 6-14 p be-
tween the turns.

Mendota (rr), Pine Tree (ss), Poor Farm (s), White Ash (cc).

The specific distinction of this species is based in large part upon the
spiral twisting of the filament. Since certain normally straight fila-
ments of other algae become spirally twisted under limnetic conditions
(vide W. & G. S. West, Proc. Roy. Soc. London Ser. B, 81: 169, fig. 1.
1909) the validity of spiral twisting as a specific character arises.
L. contorta was found in considerable quantity at different stations and
the vast majority of filaments were spirally twisted. On the other
hand numerous filaments with cells of the same size that showed no
signs of twisting were collected from other stations. I think that Lem-
mermann is correct in considering these distinct species and that the
spiral twisting of filaments in plankton species of the Myxophyceae is
a sufficiently constant character to warrant the establishment of species
in both this genus and Anabaena.

54 WISCONSIN PHYTOPLANKTON

LYNGBYA BIRGEI G. M. Smith. PI. 7, Figs. 14-15.

Bull. Torr. Bot. Cl. 43: 482, pi. 26, fiff. 28. 1916.

Filaments free-floating, solitary, never forming floccose masses;
straight or slightly flexed. Sheaths firm, at times of considerable thick-
ness, hyaline, generally homogeneous, rarely lamellated, extending for
some distance beyond the trichome. Trichomes not attenuated at apices
and without constrictions at the cross walls. Terminal cells rounded
but not capitate at distal ends. Cell shape disciform. Cell contents
rarely homogeneous and with grey to olive green contents ; usually with
numerous pseudovacuoles. (Euplanktoiit).

Cells 18-23 IL broad, 2-5.5 long. Sheaths .5-4 ^ thick.

Balsam (rr), Bear Trap (cc), Big (cc), Deer (rrr), Elizabeth (ss), Fowler
(rrr), Half Moon (c), Kegonsa (aa), Lac la Belle (rr), Little Crooked (r),
Little Wood (rr), Loveless (rr), Lower Nashotab. (rr), Mary (ss), Mendota
(cc), Mercer (rr), Monona (cc), Mudhen (rr), Nagawicka (rr), Oconomowoc
(rr), Pope (rrr), Round (3) (sss), Sand (1) (r), .Spirit (sss), Squirrel (sss),
Upper Nashotah (cc), Upper Turtle (rr), Wapagossett (cc), Waubesa (cc),
Wolf (r).

This is undoubtedly the alga that Trelease (Trans. Wis. Acad. Sci.,
Arts, & Lett. 7: 124, pi. 10, fig. 6. 1888) reported from Lake Mendota
as Lyngbya Wollei Farlow. L. Wollei has been shown to be a Plecto-
nema (P. Wollei Farlow) and Trelease 's determination is undoubtedly
a mistake.

TRICHODESMIUM Ehrenberg 1830.

Trichomes laterally joined to form spindle- to scale-shaped, free-
floating colonies that are not enclosed by a gelatinous sheath. Trichomes
cylindrical, straight or spirally twisted, of the same thickness through-
out or with apices slightly attenuated. Apical cell undifferentiated,
or rounded and slightly capitate. Sheaths of trichomes very delicate.
Cells disciform to barrel-shaped. Cell contents homogeneous, granu-
lose, or with numerous pseudovacuoles. Heterocysts and resting spores
lacking.

Reproduction by the formation of hormogones.

TKICHODESMIUM LACUSTRE Klebahn. PI. 8, Fig. 1.

Forschungsbr. a. d. Biol. Stat. zu Plon 3: 13. 1895; Flora 80: 271, pi. 4, flgy.
31-33. 1895.

Trichomes laterally joined to form plate-like, free-floating masses
that are not enclosed by a gelatinous envelope. Filaments with a very
delicate, homogeneous sheath. Trichomes straight, not attenuated at
the apices, and with terminal cells rounded but not capitate. Cells

WISCONSIN PHYTOPLANKTON 55

disciform, with straight or markedly convex sides. Cell contents occa-
sionally homogeneous and pale to bright blue-green in color ; generally
with numerous pseudovacuoles. Trichomes without heterocysts or
spores. ( Euplanktont) .

Cells 5-7 fi broad, 5-7 //. long. Colonies up to 1 mm. in length.

Amicoy (rrr), Beaverdam (r), Island (rr), Lake of the Woods (rrr), Little
Bass (1) (rr), Mud (1) (s), Nicaboyne (rr), Rice (1) (rr), Wild Goose (rrr).

The general appearance of the colony at once suggests an Aplianizo-
menon species with cells shorter and more rounded than the familiar
A. flos-aqiMe. I have examined a sufficient number of colonies to feel
confident in confirming Klebahn's statement that there are no spores
or heterocysts in the alga under consideration. This being the case it
is impossible to refer the species to Aphanizomenon, but it should be
considered a freshwater species of the common Trichodesmium of tropi-
cal seas.

Family NOSTOCACEAE.

Filaments free-floating, sessile, epiphytic, or endophytic ; solitary or
in colonies of microscopic to macroscopic size that are definitely or in-
definitely shaped. Trichomes always unbranched ; straight, flexed, spi-
rally twisted, or irregularly interwoven. Sheath rarely firm and nar-
row; generally copious, gelatinous, hyaline or colored, and distinct or
confluent with the colonial envelope. Trichomes generally the same
thickness throughout and with spherical to cylindrical cells. Hetero-
cysts either terminal or intercalary, solitary or catenate. Resting
spores variously shaped, adjacent to or remote from the heterocysts;
formed in all genera. Cell contents homogeneous, granulose, or with
pseudovacuoles ; grey or variously colored.

Reproduction by fragmentation of colony, hormogones, and resting
spores.

KEY TO THE GENERA.

Trichomes solitary or interwoven to form flocculent masses of

small size ANABAENA

Trichomes laterally joined to form small plate-like colonies APHANIZOMENON

ANABAENA Bory 1822.

Filaments free-floating or forming a delicate mucous layer; solitary
or in floccose colonies. Triehomes the same thickness throughout or
slightly attenuated at the apices; straight, spiral, circinate, or aggre-
gated without definite order. Sheaths delicate or copious, gelatinous,
hyaline, homogeneous, rarely confluent with the colonial envelope ; some-

56 WISCONSIN PHYTOPLANKTON

times entirely lacking. Cells spherical to barrel-shaped, rarely cylindri-
cal, never disciform. Heterocysts approximately spherical, always in-
tercalary, generally solitary and with several in a filament. Spores
variously shaped, contiguous to or remote from heterocysts, solitary or
in short catenate series. Cell contents homogeneous, granulose, or with
numerous pseudovacuoles ; grey, blue-green, or variously colored.
Reproduction by hormogones and spores.

KEY TO THE SPECIES.

Filaments straight or slightly curved.

Spores spherical A. PLANCTONICA

Spores longer than they are broad.
Length of spores not over twice their breadth.
Breadth of spores less than twice that of vegetative cells.
Spores oval to elliptic in optical cross section.

Vegetative cells less than 8 M broad A. AFFINIS

Vegetative cells over 10 M broad A. LIMITETICA

Spores hexagonal in optical cross section A. MACEOSPORA

Breadth of spores more than twice the vegetative cells A. LEVANDERI

Length of spores at least three times their breadth A. BOENETIANA

Filaments spirally, circinately, or irregularly twisted.
Trichomes solitary, not forming floccose masses.

Curving of trichome a definite spiral A. SPIEOIDKS

Curving of trichome not a definite spiral.

Length of spore at least four times breadth . . A. AUGSTUMALIS I. C. MAECHIA

Length of spore about twice the breadth A. CIBCINALIS

Trichomes forming a floccose mass.

Spores in a mass at center of colony A. LEMMEBMANNI

Spores not in a mass at the center of the colony.
Trichomes loosely associated, individual filaments some-
times in spiral turns A. CIBCINALIS

Trichomes greatly and irregularly twisted to form com-
pact masses A. FLOS-AQTJAB

ANABAENA PLANCTONICA Brunnthaler. PL 8, Fig. 2.
Sitzenbr. d. kais. Ak. d. Wiss. Wien 112, Abt. 1 : 292. 1903.

Filaments free-floating, solitary, straight, or slightly bent. Trichomes
enclosed by a copious, hyaline, very gelatinous sheath. Vegetative cells
spherical, hemispherical, or broadly elliptic. Heterocysts spherical.
Spores solitary, remote from or adjacent to heterocysts, spherical or
slightly elongate, somewhat broader than the vegetative cells. Cell con-
tents rarely homogeneous, usually with numerous pseudovacuoles. (Eu-
planktont) .

Vegetative cells 9-15 p broad; heterocysts 12-14 p. broad; spores
12.5-20 ^ broad, 12.5-30 p. long.

Birch (1) (cc), Center (cc), Cranberry (cc), Devils (2) (ss), Rock (cc).

WISCONSIN PHYTOPLANKTON 57

Many juvenile spores of other species are spherical but the spores of
this species never become appreciably elongated.

ANABAENA AFFINIS Lemmermann. PI. 8, Fig. 7.
Abh. Nat. Ver. Bremen 14: 261, pi. 1, figs. 12-13, 16-17. 1897.

Filaments solitary, free-floating, straight or slightly flexed; with a
wide, homogeneous, hyaline, faintly discernible gelatinous envelope.
Mature vegetative cells generally spherical; rarely with homogeneous
contents, usually with pseudovacuoles. Heterocysts spherical. Spores
generally remote from heterocysts, short or elongate cylindrical, with
rounded ends and covered with a thick, smooth wall. (Facultative
planktont) .

Cells 5-6 p. broad; heterocysts 7.5-10 ft broad; spores 9.5-12 ^ broad,
17-26 (i long.

Lindy (rr), Lost (rr), North Turtle (c), Pardee (sss), Poplar (ss), Sand
(1) (s).

ANABAENA LIMNETICA Gr. M. Smith. PI. 8, Fig. 8.

Bull. Torr. Bot. Cl. 43: 481, pi. 26, fig. 27. 1916.

Filaments free-floating, solitary, straight or slightly flexed; with a
copious, homogeneous, hyaline sheath. Vegetative cells spherical or
with poles flattened. Heterocysts spherical. Spores smooth-walled,
solitary, broadly ovoid, remote from or adjacent to the heterocysts. Cell
contents rarely homogeneous, generally with numerous pseudovacuoles.
(Euplanktont).

Cells 12-15 p broad ; heterocysts 10-14 ^ broad ; spores 17-20 /* broad,
20-30 [ji long.

Bear Trap (ss), Birch (1) (cc), Soft (ss), Tamarack (cc), White Ash (ss).

ANABAENA MACROSPORA var. ROBUSTA Lemmermann. PI. 8, Fig. 6.
Bot. Cent. 76: 164. 1898.

Filaments solitary, free-floating, straight or slightly bent, frequently
attaining a considerable length; with a copious, hyaline, homogeneous,
gelatinous envelope. Mature vegetative cells spherical or subspherical
with flattened ends. Heterocysts spherical. Spores solitary or in pairs,
adjacent to or remote from heterocysts, cylindrical with conical ends
and hexagonal in optical cross section. Spore wall smooth and thick.
Cells containing numerous pseudovacuoles. (Euplanktont).

Cells 12-16 ^ broad, 9-12 ju. long ; heterocysts 12-16 /* broad ; spores
17-19 /* broad, 30-34 /* long.

Camp (cc), Squirrel (ss).

58 WISCONSIN PHYTOPLANKTON

ANABAENA LEVANDERI Lemmermann. PI. 8, Figs. 4-5.
Ber. d. D. Bot. Ges. 24: 536. 1906.

Filaments solitary, free-floating, straight or slightly flexed, not en-
closed by a gelatinous sheath. Trichomes cylindrical, slightly con-
stricted at the cross walls of the cells. Vegetative cells twice as long as
they are broad, cylindrical, with rounded ends. Heterocysts hyaline,
spherical or ellipsoid. Spores solitary, adjacent to or remote from the
heterocysts, twice as broad as the vegetative cells, ellipsoid in shape.
Cell contents rarely homogeneous and pale blue-green to grey ; usually
with numerous pseudovacuoles. (Euplanktont).

Cells 4-6 n broad, 11-33 p. long ; heterocysts 6.5-8 p. broad, 6.5-9.5 ^
long ; spores 8-15 p. broad, 19-45 p. long.

Chain (sss).

The dimensions of all specimens found in Chain lake have been near
the minimal limits set by Lemmermann.

ANABAENA BORNETIANA Collins. PI. 8, Fig. 3.
Erythrea4: 120. 1896.

Filaments free-floating, straight or slightly curved. Vegetative cells
spherical or slightly shorter than they are broad, with homogeneous
pale blue-green contents. Sheaths of trichomes very delicate. Hetero-
cysts spherical to elongate. Spores elongate cylindrical, with rounded
ends, adjacent to and on both sides of, or remote from the heterocysts.
( Tychoplanktont) .

Vegetative cells 12 p, broad ; heterocysts 13-14 p. broad, 13-20 p. long;
spores 15-20 p. broad, 50-90 p. long.

George (rr).

Only a few filaments of this species were found in George lake and
these contained but few spores which were not always adjacent to the
heterocysts. The species may, therefore, not be A. Bornetiana for Col-
lins states that the spores are always adjacent to the heterocysts.

ANABAENA AUGSTUMALJS var. MARCHICA Lemmermann. PI. 8, Figs. 9-10.
Forschungsbr. a. d. Biol. Stat. zu Plon 12: 147. 1905.

Filaments solitary, free-floating, more or less bent but not circinate,
without a gelatinous envelope. Vegetative cells spherical, broadly ellip-
soid or cylindrical ; with numerous pseudovacuoles. Heterocysts spheri-
cal or slightly elongate. Spores remote from heterocysts, elongate cylin-

WISCONSIN PHYTOPLANKTON 59

drical, with rounded ends. Spore wall delicate, smooth, and hyaline.
(Facultative planktont).

Cells 5-7 fj, broad, 5-9.5 p. long; heterocysts 8-9.5 /* broad, 8-14 ^
long ; spores 9.5-12 /x broad, 40-70 /* long.

Bone (ss), Center (cc).

ANABAENA SPIROIDES var. CRASSA Lemmermann. PI. 9, Figs. 1-3.

Bot. Cent. 76: 155. 1898; Kryptogamenfl. d. Mark. Brandenburg 3, Algen'l:
188, 159, figs. 15-16. 1907.

Filaments solitary, free-floating; forming a regular, evenly spaced
spiral enclosed by a very transparent, homogeneous, gelatinous envelope.
Cells spherical or with flattened ends. Heterocysts spherical, hyaline
or pale yellow. Spores solitary, remote from the heterocysts, generally
broadly ovoid. Cell contents rarely homogeneous, usually with numer-
ous pseudovacuoles. (Euplanktont).

Cells 11-15 fj. broad ; heterocysts 10-17 p broad ; spores 20-25 ^ broad,
27-42 (generally 27-31) /x long. Spirals 50-60 p. broad and 45-55 /*
between turns.

Big Butternut (cc), Big St. Germain (cc), Granite (cc), Hooker (c), Ke-
gonsa (a), Long (2) (sss), Little Butternut (cc), Mendota (cc), Monona (aa),
North Twin (sss), Round (3) (ss), South Turtle (c), Vermilion (ccc).

ANABAENA CIRCINALJS (Kutzing)Rabenhorst. PI. 9, Figs. 4-5.

Algen No. 209. 1852; Phillips, Grevillea 9: 5, pi. 134, figs. e-g. 1880; Bornet
et Flahault, Ann. Sci. Nat. 7 Ser. Bot. 7: 230. 1888.

Anabaena Hassallii (Kiitzing) Wittrock. Bot. Not. 1882: 58. 1882.

Filaments free-floating, rarely solitary, curved or sigmoid; usually
greatly and irregularly twisted to form floccose masses. Filaments
with or without a copious, hyaline, gelatinous envelope. Cells spheri-
cal or appreciably flattened at the poles, generally with numerous
pseudovacuoles. Heterocysts spherical to subspherical. Spores usu-
ally remote from the heterocysts, cylindrical, with rounded ends when
mature, frequently curved and with smooth walls. (Euplanktont).

Cells 8-14 fi broad; heterocysts 8-10 /* broad; spores 16-18 p. broad,
26-30 /j. long when mature.

Center (ss), Chain (sss), Lac la Belle (rr), Mercer (rr), Nagawicka (rr),
Pike (r), Upper Nashotah (rr), Wapagossett (sss), Winnebago (ss).

This species differs from A. flos-aquae in the loose looping of the
trichomes, the larger vegetative cells and the broader spores.

60 WISCONSIN PHTTOPLANKTON

var. MACROSPOBA (Wittrock) de Toni. PI. 9, Fig. 6; PL 10, Fig. 1.

Sylloge algarum 5: 445. 1907.

Anabaena Hassallii var. macrospora Wittrock, Bot. Not. 1882: 59, figs. 7-3.
1882.

Vegetative cells somewhat smaller but with much narrower and pro-
portionally longer spores.

Cells 7-8 p. broad ; heterocysts 7.5-10 p. broad ; spores 9-10.5 p. broad,
28-42 p long.

Camp (sss).

ANABAENA FLOS-AQUAE (Lyngbye) de Brebisson. PI. 10, Figs. 2-4.

MSm. de la soc. Acad. de Falaise 1835: 36. 1836; Kutzing, Tabulae Phycol. 1:
61, pi. 94, fig. 4. 1848; Bornet et Flahault, Ann. Sci. Nat. 7 Ser. Bot. 7: 228.
1888.

Filaments free-floating, densely coiled, irregularly twisted and inter-
woven to form a floccose colony. Cells spherical or cylindrical with
convex sides ; generally containing numerous pseudovacuoles. Hetero-
cysts broader and longer than the vegetative cells. Spores cylindrical,
with rounded ends, usually curved, solitary or in short catenulate
series ; generally adjacent to, rarely remote from the heterocysts. (Eu-
planktont) .

Vegetative cells 4-8 (generally 5.5) p. broad; heterocysts 6-9 p. broad;
spores 7-13 p. broad, 20-50 p. long.

Bear (1) (cc), Birch Island (r), Browns (cc), Camp (ss), Catfish (ss),
Catherine (rr), Cochrane (sss), Crab (r), Crawling Stone (rrr), Crooked (sss),
Des Moines (rr), Devils (1) (r), Eagle (sss), Fish (rr), Grassy (r), Green
(2) (sss), Half Moon (rr), Hooker (r), Horse (rrr), Jag (rr), Jennie (ss),
Kegonsa (rr), Lac Court Oreilles (ss), Lac la Belle (r), Little Crooked (rr),
Little Wood (r), Long (1) (rr), Long (3) (rr), Lower Nashotah (rr), Lynx
(sss), Mary (rr), Mendota (c), Mercer (rr), Mill (rr) Mud (2) (c), Nancy (s),
Oconomowoc (r), Okauchee (rr), Palmer (rr), Pine Tree (rr), Poplar (rr),
Round (1) (rr), Hound (3) (r), Rudolph (rrr), Sanford (c), Shell (rrr),
Sishebogema (rr), South Crab (rr), Squirrel (rr), Upper Nashotah (r), Upper
Nemahbin (rr), Waubesa (c), Wildcat (sss), Wolf (r).

var. TRELEASII Bornet et Flahault. PL 10, Figs. 5-7.

Ann. Sci. Nat. 7 Ser. Bot. 7: 230. 1888.

Anabaena mendotae Trelease, Trans. Wis. Acad. Sci., Arts, & Lett. 7: 123,
pi. 10, flg. 5. 1889.

Cells smaller and with spores somewhat narrower and proportionally
longer. ( Euplanktont ) .

Vegetative cells 3-5 p. broad, 4.5-12 p. long ; heterocysts 4.5-6 p. broad,
6-8 p. long ; spores 6-8 p. broad, 20^40 p. long.

Mendota (aa), Waubesa (s).

WISCONSIN PHYTOPLANETON 61

ANABAENA LEMMERMANNI P. Richter. PI. 10, Fig. 8; PI. 11, Fig. 1.

Forschungsbr. a. d. Biol. Stat. zu Plon 10: 153. 1903.

Anabaena flos-aquae Klebahn non (Lyngbye) de Breb., Flora 8O: 267, pi. 4,
Jigs. 21-22. 1895.

Filaments free-floating ; irregularly or circinately interwoven to form
a spherical or broadly ellipsoid mass, with filaments frequently radiat-
ing in loops from a common center. Vegetative cells spherical or
slightly elongate, usually containing numerous pseudovacuoles. Heter-
ocysts spherical, approximately the same size as the vegetative cells.
Spores cylindrical, with rounded ends, with inner side straight and the
outer convex ; rarely remote from heterocysts, generally forming short
catenate series on both sides of heterocysts and lying in a dense mass
at the center of the colony. The spore masses and heterocysts fre-
quently persisting long after the disappearance of the vegetative cells.
( Euplanktont) .

Vegetative cells 5.5-7 p broad, 5-8 n long; heterocysts 6-7.5 p. broad;
spores 8-11 n broad, 19-33 /x long.

Crawling Stone (rr), Diamond (r), Kawaguesaga (rr), Long (rr), Marl
(r), Oconomowoc (r), Paddock (cc), Palmer (r), Pardee (ss), Rainbow (2)
(rr), Reserve (r), Rice (1) (s),iSand (2) (rr), Taylor (ss), Trout (s).

The species differs from A. flos-aquae in the regular looping of the
trichomes from a common center and the development of a large mass
of spores at the center of the colony. The persistence of the spores
after the disappearance of the vegetative cells is very common and
certain of the records for the species are based upon observation of the
spore masses only.

APHANIZOMENON Morren 1838.

Trichomes straight slightly flexed, or curved ; in lateral contact with
one another to form small, macroscopic, free-floating, feathery, plate
or scale-like opaque colonies. Trichomes destitute of a gelatinous
sheath, sometimes constricted at cross walls of cells, and slightly attenu-
ated at the apices. Cells cylindrical, with flattened ends. Heterocysts
intercalary, cylindrical. Spores elongate, cylindrical and with flattened
ends; solitary, adjacent to or remote from the heterocysts.

Reproduction by the formation of hormogones and resting spores.

APHANIZOMENON FLOS-AQUAE (L)Ralfs. PI. 11, Figs. 2-4.

Ann. & Mag. of Nat. Hist. 2 Ser. 5: 340, pi. 9, fig. 6. 1850; Klebahn, Flora 80:
271, pi. 4, figs. 27-30. 1895.

Trichomes straight or slightly curved, laterally joined to form a flat
flake- or scale-like plate. Cells cylindrical, with flattened ends, about

52 WISCONSIN PHYTOPLANKTON

three times as long as they are broad, generally with numerous pseudo-
vacuoles. Heterocysts cylindrical, with straight or slightly convex sides,
without a distinct polar nodule. Spores elongate, cylindrical, with
rounded or somewhat flattened ends, generally some distance from the
heterocysts. ( Euplanktont) .

Cells 4r-6 p. broad, 5-15 //. long ; heterocysts 5-7 M broad, 7-20 /x long ;
spores 6-8 p. broad, 35-80 p long.

Amicoy (aa), Balsam (ss), Bear (3) (rr), Beaverdam (rr), Big (r), Big
Butternut (rr), Birch (1) (c), Bone (rr), Camp (r), Catfish (sss), Center
(rrr), Chetac (aaa), Cranberry (ss), Crawling Stone (rrr), Deer (rrr), Dun-
ham (rr), Found (rr), Fowler (rr), Granite (a), Green (2) (ss), Half Moon
(sss), Hillman (sss), Hooker (cc), Horse (rrr), Horseshoe (1) (rr), Island
(c).Kawaguesaga (ccc), Kegonsa (cc), Lac la Belle (rr), Little Bass (2) (rr),
Little Butternut (s), Little Rice (1) (s), Little Wood (rr), Long (3) (rr),
Lost (ss), Loveless (ss), Lower Nashotah (rr), Mendota (s), Mud (3) (rr),
Nagawicka (rr), North Twin (rrr), Oconomowoc (rr), Okauchee (rr), Par dee
(cc), Pewaukee (rr), Pike (rr), Plum (r), Pokegama (2) (rrr), Pokegama

(3) (aaa), Poplar (rrr), Prairie (aaa), Reserve (rr), Rice (1) (ss), Round
(1) (sss), Round (2) (ss), St. Croix (ccc), Sand (1) (r), Sand (3) (r), Sand

(4) (r), Sahford (sss), Shell (rrr-), South Turtle (sss), Squirrel (a), Streitor
(rr), Tied Canoe (sss), Upper Nashotah (rr), Upper Nemahbin (r), Upper
Turtle (rr), Vermilion (r), Waubesa (s), White Ash (rr), Whitefish (rr),
White Sand (ss), Winnebago (r).

When the alga occurs in any quantity the lake appears to be filled
with small pieces of macerated grass and it is one of the few plankton
genera that can be determined without the aid of a microscope. The
colony is so opague that the heterocysts cannot be seen while the colony
is intact but after a mount has been standing a few minutes the colonies
begin to dissociate into the component filaments and observation of the
heterocysts and spores is then an easy matter. The colonies are fre-
quently sterile and it is generally only during the colder months of the
year that there is a formation of spores.

Family RIVULARIACEAE.

Filaments rarely solitary, generally forming sessile or free-floating
spherical, hemispherical, or amorphous colonies. Trichomes gradually
attenuated from a broad basal cell to a hair-like apical cell. Sheaths
copious, homogeneous or lamellated, hyaline or colored, firm or gelat-
inous; enclosing one or more trichomes. Cells hemispherical, spheri-
cal, or disciform with convex sides at the basal portion of the trichome,
elongate cylindrical in the apical region. Cell contents variously col-
ored ; homogeneous, granulose, or with numerous pseudovacuoles. Trich-
omes simple or with "false branching". Heterocysts solitary; usually

WISCONSIN PHYTOPLANKTON 63

at base of trichomes, rarely intercalary. Spores, when present, soli-
tary and adjacent to heterocysts.

Reproduction by formation of trichomes and spores.

GLOEOTRICHIA J. G. Agardh 1842.

Filaments always in colonies; free-floating or sessile; spherical to
hemispherical, tough and leathery to gelatinous, hyaline or colored.
Trichomes attenuated to fine hair-like processes at the distal end, en-
closed by gelatinous sheaths that are distinct at the base and confluent
at the apex. Filaments containing one trichome, but at times showing
false branching. Heterocysts spherical to hemispherical, solitary; at
the base of the trichomes. Spores cylindrical, solitary, always adjacent
to the heterocysts. Vegetative cells convexly disciform to short cylin-
drical at base of trichomes, elongate cylindrical with straight sides at
apex of trichomes.

Reproduction by hormogones and resting spores.

GLOEOTRICHIA ECHINULATA ( J. E. Smith) P. Richter. PI. 11, Figs. 5-6.

Forschungsbr. a. d. Biol. Stat. zu Plon 2: 31, fl.gs. 1-8. 1894.

Conferva echinulata J. E. Smith, Eng. Bot., pi. 1378. 1804.

Rivularia echinulata J. E. Smith, Eng. Bot. index; P. Richter, Forschungsbr.
a. d. Biol. Stat. zu Plon 2: 45. 1894; Leminermann, Kryptogamenfl. d. Mark
Brandenburg 3, Algen 1: 255, 245, figs. 1, 6. 1907.

Gloeotrichia pisum Bornet et Flahault (p.p.) non Thuret, Bull. Soc. Bot.
France 31: 80. 1884; Ann. Sci. Nat. 7 Ser. Bot. 4: 366. 1886; Trelease, Trans.
Wis. Acad. Sci., Arts, & Lett. 7: 124-125 (with fig.) 1889.

Colonies always free-floating, spherical; up to 2 mm. in diameter.
Filaments radially arranged about a common center but becoming ir-
regular in arrangement on slight pressure. Sheaths hyaline, homogene-
ous, distinct at base, apex frequently confluent with colonial envelope.
Trichomes broad at base, attenuated to long, colorless, hair-like pro-
cesses. Lowest vegetative cell of trichome hemispherical ; those a short
distance from base disciform with markedly convex sides; those in
middle of trichome cylindrical ; while the cells in the apical region are
elongate cylindrical. Basal cells completely filled with cytoplasm,
apical cells with cytoplasm restricted to the median portion. Cell con-
tents rarely homogeneous, usually with numerous pseudovacuoles.
Heterocysts at base of trichome, spherical. Spores, when present, ad-
jacent to heterocysts, elongate cylindrical with rounded ends.

Cells at base of trichome 8-10 p. broad; at apex 1-2 ^ broad; hetero-
eysts 7-10 /* broad ; spores 8-10 p. broad, 40-54 //. long.

Bass (3) (rr), Bear (3) (rr), Bear Trap (rr), Beaverdam (rr), Birch (2)
(se), Birch Island (r), Bone (rr), Carroll (rr), Catherine (sss), Chetac (as),

64 WISCONSIN PHYTOPLANKTON

Clare (ss), Crawling Stone (rrr), Des Moines (cc), Diamond (ss), Duck (rr),
Dummy (rr), Dutchmans (ss), Fish (ss), Fowler (sss), Grindstone (rr),
Half Moon (ss), Horseshoe (1) (ss), Horseshoe (2) (rr), Howey (rr), Island
(BS), Jennie (rr), Kegonsa (aa), Kimball (rr), Lac Court Oreilles (ss), Lake
of the Woods (r), Lindy (rr), Long (1) (sss), Loon (r), Mendota (s), Monona
(cc), Nancy (ss), North Twin (r), Mercer (rrr), Middle McKenzie (ss), Mud
(3) (aa), Oconomowoc (rr), Owen (rrr), Razorback (aa), Reserve (rr), St.
Croix (rr), Sand (1) (rr), Sand (3) (rr), Shell (rr), Soft (rr), Trout (cc),
Waubesa (cc), Whitefish (sss), Wild Goose (rr), Winnebago (r).

A bloom of this alga can be recognized at once by the minute seed-like
colonies surrounded by an aureole of whitish threads. It was first
noted by Davis in England in 1804 and the plant figured and described
by Smith in his English Botany. The various references to the alga
before the recognition of a definite plankton flora have been compiled
by Bornet and Flahault as well as P. Richter. Since the study of the
plankton flora by phycologists the alga has been found in the lakes of
most European countries. Although there seems to be but a single
species of the Rivulariaceae found free-floating in lakes and ponds the
nomenclatorial treatment of this species is quite varied. Bornet and
Flahault affirm that it is the common Gloeotrichia pisum, which ordi-
narily grows attached to submerged plants along the shore, that has
broken away and become free-floating. They hold that Rivularia
echinulata J. E. Smith (whose dimensions are the same as those of
G. pisum) is nothing but a free-floating G. pisum. In my observations
on the algae of our lakes there is no correlation between the appearance
of G. pisum and G. echinulata in the same lake in Wisconsin. In the
region of Madison, G. pisum does not appear until the middle of July
and yet at one time there was a heavy bloom of G. echinulata, on the
28th of June, a time when there was no G. pisum along the shore. I
am convinced that the sessile Gloeotrichia is not the one found in the
plankton and that Richter is quite right in reviving the old specific
name echinulata. Some investigators hold that Gloeotrichia is but a
sub-genus of Rivularia, but I have followed Bornet and Flahault in
considering the two distinct. This distinction is based upon the occur-
rence of spores in Gloeotrichia and a lack of spores in Rivularia.

WISCONSIN PHYTOPLANKTON 65

Class PHAEOPHYCEAE.

Plants usually of macroscopic size and definitely shaped. Cells vari-
ously shaped and containing brown chromatophores in which a brown
pigment, phaeophycin, masks the chlorophyll. Cell wall not conspicu-
ously impregnated with silica and cells generally immobile in the vege-
tative phases.

Asexual reproduction by vegetative cell division, aplanospores, and
zoospores.

Sexual reproduction by isogamous zoogametes ; or heterogamous with
a fusion of zoogametes of unequal size, or a union of a large immobile
oosphere and a small motile antherozooid.

All of the complex non-motile members of this class are marine and
only unicellular or simple colonial forms are found in fresh waters.
These freshwater forms have the motile phase dominant, as a rule, and
form the subclass Chrysomonadineae of the Phaeophyceae. Many
place all of the colorless or brown chromatophored motile unicellular
organisms in a class by themselves, the Flagellatae, but, as I have stated
elsewhere, the group of the Chrysomonadineae seems sufficiently related
to the Phaeophyceae to warrant uniting the two.

Sub-class CHRYSOMONADINEAE.

Cells with one or more definite, disciform, laminate, or reticulate,
golden-brown chromatophores. Cells free-swimming or sessile, solitary
or in colonies of definite to indefinite shape. Life cycle generally with
the motile phase dominant but sometimes developing into amorphous or
rhizopodial palmella stages. Cells either naked or with a gelatinous
to definitely constituted periplast. Individual cells with 1-2 anterior
or lateral cilia of equal or unequal length; 1-10 contractile vacuoles,
generally at the anterior end; with or without an eyespot; and with
one or more chromatophores. Symmetry of cells bilateral, not inter-
rupted by a lateral or longitudinal grooving. Nutrition holophytic or
fiaprophytic ; assimilation product leucosin or fat, never starch.

Asexual reproduction by longitudinal or transverse division of cells.
Ilesting stages with heavy walls known in many genera.

Sexual reproduction as yet unknown in the sub-class.

WISCONSIN PHYTOPLANKTON

KEY TO THE DIVISIONS.

Motile phase dominant, rhizopodial or palmella phase rare . EUCHRYSOMONADINAE
Immobile phase dominant, motile phase known or unknown.

Cells spherical to ovoid, embedded in a gelatinous envelope . . . HYDBUBINAE
Cells with pseudopodial processes ...................... RHIZOCHBYSIDINAE

Division EUCHRYSOMONADINAE.

Cell structure and organization as noted in the description of the
sub-class. Ciliate phase dominating the life history. Palmella or
rhizopodial phases known but not the general rule.

KEY TO THE ORDERS.

Motile phase with one fiagellum CHEOMULINALES

Motile phase with two flagella.

Flagella of the same length ISOCHBYSIDALES

Flagella of unequal length OCHBOMONADALES

Order CEROMUUNALES.

Cells generally solitary, rarely colonial ; free-floating or sessile. Mo-
tile phase with a single apical flagellum. Chromatophores reticulate,
laminate, or disciform ; generally two in each cell. Apical contractile
vacuoles present or lacking. Cells either naked or with a definite, homo-
geneous or sculptured periplast.

Reproduction by vegetative division of cells. Thick-walled resting
stages known in certain genera.

KEY TO THE FAMILIES.

Cells naked EUCHBOMULINACEAE

Cells with a differentiated periplast , . MALLOMONADACEAB

Family EUCHROMULINACEAE.

Cells naked, without a differentiation of the periplast. Cells with
sharply defined disciform to laminate chromatophores, and without
contractile vacuoles. Flagellum single.

There are several genera with many species in the family but only
one of them, Chrysamoeba, has been noted in the plankton of the state.

WISCONSIN PHYTOPLANKTON 67

CHRYSAMOEBA Klebs 1893.

Cells solitary, free-floating, with a mono-flagellate motile phase and
an amoeboid non-motile phase. Motile phase broadly ovoid, naked,
with two elongate, laminate, golden-brown chromatophores ; a large
non-contractile vacuole, 2-3 small contractile vacuoles; and a single
flagellurn slightly longer than the cell. Eye-spot lacking.

Non-motile phase solitary or in small clumps, with several simple or
branching pseudopodial processes extending in all directions. Chro-
matophores and vacuoles as in the motile phase.

CHRYSAMOEBA RADIANS Klebs. PI. 12, Fig. 1.
Zeits. f. wiss. Zool. 55: 406, pi. IS, figs, la-lb. 1893.

Specific characters as described above. (Euplanktont).
Motile phase 8-10 ^ broad, 12-15 /*, long; amoeboid phase (without
processes) 12-17 p. broad, (with processes) 35-40 /u, broad.

Round (4) (rr), Taylor (rr).

Family MALLOMONADACEAE.

Cells always free-swimming, solitary or colonial, never metamorphos-
ing into a palmella or rhizopodial phase. Periplast of cells or colonial
envelope with numerous small plates of silica that have long, siliceous,
needle-like processes. Cells ovoid to ellipsoid, with one flagellum, a
number of contractile vacuoles and two long laminate chromatophores.

/

KEY TO THE GENERA.

Cells solitary MAIXOMONAS

Cells in spherical colonies CHBYSOSPHAEKELLA

MALLOMONAS Perty 1852.

Cells always solitary, free-swimming, with a single flagellum at the
anterior end. Periplast of cells with small circular or angular siliceous
discs covering the entire surface of the cell or restricted to one or both
ends. Scales frequently arranged in regular transverse or diagonal
rows, produced into a single, long, simple or toothed, needle-like setae.
Cells containing one or more contractile vacuoles that may be apical,
median, or basal in position. Chromatophores two, parietal, laminate,
and golden-brown in color. Assimilation product leucosin.

Reproduction by vegetative cell division parallel to the long axis.
Akinetes known in many species.

gg WISCONSIN PHJTOPLANKTON

KEY TO THE SPECIES.

Setae restricted to one end of the cell.
Apical end with setae. •

Cells cylindrical M. ALPINA

Cells ovoid M. TONSURATA

Basal end "with setae M. PKODUCTA

Setae covering whole cell M. CAUDATA

MALLOMONAS ALPINA Pascher & Kuttner. PL 12, Fig. 4.

in Pascher, D. Siisswasserfl. Deutschl., Osterr., u. d. Schw. 2, Flagellatae 2: 36,
flg. 58A. 1913.

Cells ellipsoid to elongate cylindrical, with poles rounded or pointed.
Scales rhomboidal, in diagonal rows; with a single, long, straight or
curved seta. Setae confined to anterior end of cells. (Euplanktont).

Cells 8-12 p broad, 25-45 /* long.

Camp (r).

MALLOMONAS PRODUCTA (Zacharias) Iwanoff. PI. 12, Fig. 2.

Bull, de 1'Acad. Imp. d. Sc. de St. Petersbourg 5 Ser., 11: 250, pi. A, figs. 4-6.
1899.

Cells cylindrical, with straight or slightly convex sides, ends rounded
and tapering. Scales in regular transverse to diagonal rows, diamond-
shaped or laterally elongate. Setae straight or bent, confined to basal
portion of cell. Chromatophores two, golden-brown, laminate, and
parietal. (Euplanktont).

Cells 9-13 n broad, 40-70 p long.

Catfish (sss), Cranberry (ss), Crawling Stone (sss), Lac la Belle (ss),
Long (1) (ss), Otter (r), South Turtle (rrr), Upper Nashotah (rr).

var. MABCHICA Lemmermann. PI. 12, Fig. 3.
Zeits. f. Fischeri 1903: 106. 1903.

Cells shorter and relatively broader. Setae sometimes at both ends
of cells. (Euplanktont).

Cells 11-12 ti broad, 21-26 /z long.

Nancy (r), Oconomowoc (ss), Tamarack (ss).

MALLOMONAS TONSURATA Teiling. PI. 12, Fig. 5.
Sv. Bot. Tids. 6: 277, fig. 3. 1912.

Cells ellipsoid, with posterior end rounded and anterior end pointed.
Setae confined to anterior third of cell, fairly short and somewhat
curved. Scales not regularly arranged. (Euplanktont).

Cells 7-8 fj. broad, about 18 /x long.

Waupaca (rr).

WISCONSIN PHYTOPLA.NKTON 69

MALLOMONAS CAUDATA Iwanoff. PL 12, Fig. 6.

Bull, de 1'Acad. Imp. d. Sc. de St. Petersbourg 5 Ser., 11: 250, PI, B, flga. 1-8.
1899.

Cells broadly ovoid, with posterior end narrower than the anterior.
Scales oval, arranged in transverse series. Setae long, covering the
entire surface of the cell and frequently with minute teeth-like projec-
tions at the distal end. Cells with two long, parietal, laminate, chro-
matophores. ( Euplanktont) .

Cells 12-30 p. broad, 40-85 ^ long.

Beasley (rr), Birch (1) (rrr), Browns (rr), Carson (rrr), Catherine (rr),
Clare (r), Clear Crooked (rr), Crab (rr), Crawling Stone (rrr), Diamond
(rrr), Hill (ss), Jennie (rr), Kitten (sss), Lac la Belle (ss), Long (3) (ss),
Long (4) (rr), Lynx (rr), Mud (2) (ss), No Mans (s), North Turtle (r),
Okauchee (rr), Otter (sss), Pokegama (1) (rr), Pokegama (2) (r), Red Bass
(s), Rock (cc), Round (1) (sss), Rudolph (sss), St. Croix (rrr), Sand (4)
(sss), Sanford (sss), South Crab (rr), Wildcat (sss), Wild Goose (rr), Wolf
(rr).

CHRYSOSPHAERELLA Lauterborn 1896.

Cells ellipsoid to pyriform, in spherical colonies of microscopic size
that are partially embedded in a spherical, hyaline, gelatinous envelope
containing numerous, tangentially placed, minute plates of silica. An-
terior ends of cells with two short, vase-shaped projections, each bear-
ing a single, long, straight, siliceous seta of some length. Cells with
one anterior flagellum ; two elongate, parietal, golden-brown chromato-
phores ; and several vacuoles.

Reproduction by vegetative cell division. Resting akinetes unknown.

CHRYSOSPHAERELLA LONGISPINA Lauterborn. PI. 12, Figs. 7-8.
Zool. Anz. 19: 16. 1896; Zeits. f. wiss. Zool. 65: 381, pi. 18, figs. 12-16. 1899.

Specific characters as described above. (Euplanktont).
Average breadth of cells 9 p, average length 15 ,u. Colonies 50-250 p.
in. diam.

Bettine (rr), Blue Gill (ss), Boulder (rrr), Canteen (r), Elizabeth (rr),
Hill (aa), Lac la Belle (rr), Long (4) (rr), Lynx (r), Marl (rr), Mary (ss).
No Mans (rr), Oconomowoc (ss), Okauchee (s), Otter (ss), Rainbow (ss),
Round (4) (rr), Rudolph (sss), Silver (2) (ss), South Turtle (ec), Upper
Nemahbin (ss), Wild Goose (ccc).

Order ISOCHRYSIDALES.

Cells free-floating or sessile, solitary or colonial, naked or with a
definite homogeneous or sculptured periplast. Motile phase always
present, palmella or rhizopodial phase lacking. Cells variously shaped,

70 WISCONSIN PHYTOPLANKTON

always with two apical cilia of equal length ; generally with two lami-
nate, parietal, golden-brown chromatophores and without an eyespot.

The only family represented in the flora of the state is that of the
Euhymenomonadaceae.

Family EUHYMENOMONADACEAE.

Differing from other families of the order in having a definite sculp-
tured periplast and an anterior vacuolar system. Synura the sole
representative.

SYNURA Ehrenberg 1838.

Cells radially arranged in spherical to oblong-ovoid free-swimming
colonies that are not enclosed by a gelatinous sheath. Individual cells
broadly pyriform, with the narrower end towards the center of the
colony. Outer portion of cells firm, with small spines, reticulations,
or combinations of the two. Cells with two long anterior cilia of equal
length, several vacuoles, two long laminate parietal chromatophores,
and without an eyespot.

Eeproduction by division of cells and liberation of cell contents to
form amoeboid cells. Akinete formation also known.

SYNURA UVELLA Ehrenberg. PI. 12, Figs. 9-10.
Infusionsthierchen 61, pi. 3, figs. P-9\ 1&38.

Exterior of cells covered with fine spines that are generally limited
to the anterior portion. (Facultative Planktont).

Cells 8-17 /* broad, 20-35 p, broad. Colonies up to 350 /* in diam.

Camp (ss), Canteen (cc), Crawling Stone (rrr), Fowler (cc), Jenny (rr),
Kawaguesaga (rr), Little Bear (rrr), Little Crooked (rr), Long (3) (r),
Lower Nemahbin (rr), Lynx (r), Mendota (ss), Mercer (rr), Mill (ccc), Mud
(2) (rr), Nagawicka (cc), Nancy (cc), Nicaboyne (rr), No Mans (cc), North
Turtle (rr), Oconomowoc (s), Palmer (c), Pardee (sss), Pewaukee (sss),
Pope (rrr), Rainbow (1) (rr), Red Bass (ss), Round (1) (sss), Rudolph (sss),
Sand (4) (rr), Sanford (ss), South Turtle (rr).

Order OCHKOMONADALES.

Cells solitary or colonial, free-swimming or sessile, not forming pal-
mella or rhizopodial stages. Cells naked, or with a definitely shaped re-
ceptacle ; two lateral or apical cilia of unequal length, one or two golden-
brown discif orm to laminate chromatophores ; contractile vacuoles ; and
an eyespot.

WISCONSIN PHYTOPLANKTON 71

KEY TO THE FAMILIES.

Cells naked, at times in a gelatinous envelope but never a

definite receptacle OCHEOMONADACEAB

Cells within a definite receptacle DINOBRYACEAB

Family OCHROMONADACEAE.

Cells solitary or in colonies, always free-swimming, not enclosed by
a definite receptacle but at times with a hyaline, homogeneous, gelat-
inous envelope. Cells with two apical cilia of unequal length, one or
two golden-brown chromatophores, an eyespot and contractile vacuoles.

Uroglenopsis is the only representative in the local flora.

UROGLENOPSIS Lemmermann 1899.

Colonies free-swimming, with the cells embedded in a single layer at
the periphery of a copious, hyaline, homogeneous, gelatinous matrix of
spherical to broadly ellipsoid shape. Arrangement of cells radial or
somewhat irregular. Cells spherical to narrowly ellipsoid; with two
cilia of unequal length; two vacuoles at the anterior end; one or two
laminate to discif orm, parietal, golden-brown chromatophores ; and with
or without an eyespot.

Eeproduction by vegetative cell division.

UROGLENOPSIS AMERICANA (Calkins) Lemmermann. PI. 13, Figs. 1-4.

Forschungsbr. a. d. Biol. Stat. zu Plon 7: 107. 1899; Kryptogamenfl. d. Mark
Brandenburg 3, Algen 1: 449, 444, figs. 1-3, 4-6. 1908.

Uroglena americana Calkins, Ann. Rept. Mass. State. Bd. of Health 23: 655,
pi. 4, figs. 1-4. 1892; Moore, Bot. Gaz. 23; 105, pi. 10, figs. 1-11. 1897.

Colonies free-swimming, generally spherical. Cells ellipsoid, with
one basal or lateral, parietal, discif orm to laminate chromatophore. Eye-
spot single. Cilia of unequal length, with the longer 2-3 times the
length of the cell, the shorter %-V2 the length of the cell. (Euplank-
tont).

Cells 3-7 p. broad, 5-10 /* long. Colonies up to 500 /*, in diam.

Beasley (cc), Bettine (ss), Browns (ss), Camp (ss), Carson (rrr), Diamond
(rr), Eagle (sss), Fowler (cc), Howey (rr), Lac la Belle (ss), Long (3) (ss),
Long (4) (rr), Lower Nemahbin (rr), Lynx (rr), Mendota (ss), Mill (ss),
Mud (4) (cc), Nancy (rr), Oconomowoc (ss), Okauchee (rrr), Otter (ss),
Paddock (s), Pewaukee (rr), Rainbow (1) (ss), Round (4) (rr), Taylor (ss),
Wildcat (ss), Wolf (rr), Youngs (cc).

72 WISCONSIN PHYTOPLA.NETON

Family DINOBRTONACEAE.

Cells solitary or in colonies, free-floating or sessile. Always attached
to the base of a conical to vase-like, colored or hyaline, smooth or sculp>-
tured receptacle. Cells with one or two laminate chromatophores, con-
tractile vacuoles, an eyespot, and two cilia of unequal length.

KEY TO THE GENERA.

Receptacles homogeneous, without growth rings DINOBRYON

Receptacles with successive growth rings HYALOBBYOX

DINOBRYON Ehrenberg 1835.

Cells free-floating, sessile, or epiphytic; solitary or in colonies; at-
tached to the bottom of conical, campanulate, or cylindrical receptacles
with open apices and pointed bases. Colonial species arbuscular, each
receptacle with the pointed ends of 1-4 other receptacles in its mouth.
Development of branching indefinite. Protoplast spindle-shaped, coni-
cal, or ovoid ; attached by a stalk to the base of the receptacle. Anterior
end of protoplast with two cilia of unequal length that project beyond
the open end of the receptacle. Cells with one or two laminate, elon-
gate, parietal, golden-brown chromatophores; several apical, lateral, or
basal contractile vacuoles; and one apical eyespot. Assimilation pro-
duct generally leucosin.

Reproduction by longitudinal division of cell contents to form ovoid
daughter cells that migrate to the mouth of the old receptacle or leave
it entirely before developing new receptacles. Akinetes known.

The specific limits of colonial plankton species of this genus are very
poorly defined and it is almost impossible to draw a sharp line of de-
marcation between the various species. I have indicated as species the
centers around which the variations seem to occur.

KEY TO THE SPECIES.

Cells solitary.

Cell shape conical, elongate D. CALICIFORMB

Cells broadly spindle-shaped D. TABELLABIAE

Cells in colonies.

Branching of cells markedly divergent D. DIVKEGEXS

Branching of cells not sharply divergent.
Cells elongate conical.

'Sides of receptacles straight D. STim-ATUM

Sides of receptacles undulate D. BAVABICUM

Cells campanulate , .D. SJTTULABIA

WISCONSIN PHYTOPLANKTON 73

DINOBRYON CALICIFORME Bachmann. PI. 13, Figs. 5-6.
Arch. f. Hydrob. u. Planktonkde. 3: 82, fig. XI". 1908.

Cells solitary; epiphytic upon the gelatinous envelope of various
colonial Myxophyceae. Receptacles elongate conical, with a sharply
pointed base. Protoplast the same shape as the lower two-thirds of re-
ceptacle. Chromatophores two, laminate, parietal, and golden-brown
in color. Eyespot single. Cilia not as long as the cell. (Euplank-
tont).

Receptacles 5-6 ^ broad at apex, 30-40 p long.

Embedded in or on gelatinous envelope of Coelosphaeriwn Naegeli-
anum and Microcystis aeruginosa.

Browns (sss).

DINOBRYON TABELLARIAE (Lemmermann) Pascher. PI. 13, Figs. 7-9.

Siisswasserfl. Deutschl., osterr. u. d. Schw. 2, Flagellatae 2: 66, flgs. 105*-105b.
1913.

Dinobryon utriculus var. tabellariae Lemmermann, Arkiv for Botanik 2,
No. 2: 119, pi. 1, fig. 19. 1904.

Cells solitary; epiphytic upon filaments of Tabellaria. Receptacle
broadly spindle-shaped, with the base produced into a short stipe. Pro-
toplast attached to side of lower portion of receptacle, ovoid in shape
and with the usual contents of the genus. (Euplanktont).

Receptacles 7-10 /* broad at center, 4-5 at apex ; 18-22 p long.

Crawling , Stone (r), Long (3) (rr), Sand (4) (s).

DINOBRYON BAVARICUM Imhof. PI. 13, Fig. 10.

Zool. Anz. 13: 484. 1890; Lemmermann, Bot. Not. 1903: 78, pi. 3, flgs. 3-4.
1903.

Cells in free-floating compact colonies. Receptacles of individual
cells elongate-conical. Base of receptacle very much produced with
sides almost parallel; expanded portion of receptacle with undulate
sides. Seasonal variation pronounced, the receptacles being much
longer during the summer. (Euplanktont).

Receptacles 6.5-8.5 /* broad ; 45-100 /* long.

George (ss), Harris (rr), Marl (ss), Oconomowoc (ss), Speese (ss), Tied
Canoe (ss), White Sand (s).

^ •*

A»<

74 WISCONSIN PHYTOPLANETON

DINOBRYON STIPITATUM Stein. PI. 13, Fig. 11.

Der Organismus der Infusionstiere 3: pi. 12, fig. 5. 1878; Pascher, D. Siiss-
wasserfl. Deutschl. osterr. u. d. Schw. 2, Flagellatae 2: 73, fig. 118. 1913.

Cells always in narrow, fairly dense, free-floating colonies. Recep-
tacles of individual cells elongate-conical, with bases produced into stipes
with nearly parallel sides. Sides of receptacle not undulate. Indi-
vidual receptacles of colony not divergent from one another. Seasonal
variation chiefly in elongation of apical cells of colony. (Facultative
Planktont).

Receptacles 6—8 p. broad ; 56—96 p, long.

Marl (ss), Oconomowoc (cc), Round (4) (sss), 'South Turtle (IT).

DINOBRYON SOCIALE Ehrenberg. PI. 13, Fig. 12.

Abh. d. k. Ak. d. Wiss. Berlin 1833: 279. 1835; Die Infusionsthierchen 125,
pi. 8, fig. 9. 1839; Pascher, Siisswasserfl. Deutschl. osterr. u. d. Schw. 2,
Flagellatae 2: 73, figs. 116-117. 1913,

Cells in free-floating colonies. Individual receptacles somewhat di-
vergent from one another and producing a fairly loose colony. Recep-
tacles conical, sometimes slightly constricted below the open mouth, with
bases gradually tapering to a sharp point that is not extended to form
a process. (Facultative planktont).

Receptacles 7-8 /* broad, 30-70 /* long.

Beasley (ss), Green (1) (ss), Green (2) (cc), Mill (c), North Turtle (rr),
Oconomowoc (cc), Silver (2) (s), Trout (rr).

DINOBRYON SETULARIA Ehrenberg. PL 13, Fig. 13; PI. 14, Fig. 1.

Abh. d. k. Ak. d. Wiss. Berlin 1833: 280. 1835; Die Infusionsthierchen 124,
pi. 8, fig. 8. 1838.

Cells in free-floating, densely branching colonies. Receptacles cylin-
drical-campanulate, with the convex bases tapering abruptly to a sharp
point. Cells with shorter and broader receptacles than the other species.
Seasonal variation not so pronounced as in other species. (Facultative
Planktont) .

Receptacles 10-14 p, broad, 30-44 p long.

Devils (1) (ccc), Kawaguesaga (ss), Long (4) (ss), Lost (ss), Lower
Nemahbin (ss), Rock (ss), Round (3) (ss), Winnebago (rr).

WISCONSIN PETTOPLANKTON 75

DINOBRYON DIVERGENS Imhof . PI. 14, Fig. 2.

Jahresbr. d. Naturf. Ges. Graub lindens N. F. 80: 134. 1887.

Dinobryon cylindricum,va,r. divergens (Imhof) Lemmermann, Ber. d. D. Bot.
Ges. 18: 517, pi. 19, figs. 15-20. 1900.

Cells in free-floating densely or openly branched colonies. Recep-
tacles with conical bases and the upper portion cylindrical or with
slightly flaring mouths. The axis of the upper portion of receptacle
forming an angle of 45-90 degrees with that of the basal portion. Sides
of receptacle sometimes undulate. Seasonal variation confined to dense-
ness of branching in colony rather than changes in receptacle shape.
(Facultative Planktont).

Eeceptacles 7-8 p. broad, 35-50 p long (20-27 /A in upper portion and
15-20 in basal portion).

Beasley (s), Boulder (cc), Browns (cc), Center (ss), Devils (1) (ss),
Elizabeth (cc), George (r), Green (2) (rr), Hill (cc), Lac la Belle (ss),
Long (2) (rr), Marl (ss), Mary (cc), Meta (r), Mill (cc), Mud (1) (ss),
Nagawicka (cc), North Turtle (ss), Oconomowoc (cc), Otter (ss), Rock (ss),
Round (4) (rrr), Silver (2) (cc), Speese (cc), Tamarack (ss), Taylor (ss),
Tied Canoe (ss).

HYALOBRYON Lauterborn 1896.

Cells solitary or in branching colonies, free-floating or epiphytic.
Receptacle shape and cell contents as in Dinobryon but with the wall
of the receptacle containing a number of successive growth rings instead
of homogeneous. Wall of receptacle more delicate than Dinobryon.

HYALOBRYON MUCICOLA (Lemmermann) Pascher. PI. 14, Figs. 3-4.

D. iSiisswasserfl. Deutschl., osterr. u. d. Schw. 2, Flagellatae 2: 81, fig. 131. 1913.
Hyalobryon Lauterbornei var. mucicola Lemmermann, Ber. d. D. bot. Ges.
19: 340. 1901; Bachmann, Arch. f. Hydrob. u. Planktonkde. 8: 81, figs. XI18-
XI". 1908.

Cells solitary, epiphytic upon gelatinous envelope of colonial Myxo-
phyceae, Chlorophyceae and Phaeophyceae. Receptacle delicate, upper
portion cylindrical and with a flaring mouth, lower portion conical and
with a short stipe. Growth rings of receptacle numerous. Protoplast
ovoid, attached to base of receptacle, with two golden-brown chromato-
phores, two cilia of unequal length and an eyespot. (Euplanktont).

Receptacles 4-6 /* broad, 25-45 ^ long; stipe 4-12 p. long.

Crawling Stone (r), Lac du Flambeau (sss), Long (3) (c), Mud (2) (rr),
Round (1) (rr).

76 WISCONSIN PHYTOPLANKTON

Division HYDRURINEAE.

Cells free-floating or sessile, usually in palmella-like colonies and
motile only at the time of reproduction; rarely solitary, generally in
gelatinous colonies of microscopic to macroscopic size that have a
definite to indefinite shape. Colony capable of growth in all parts or
with growing region restricted to apex. Gelatinous sheath of cells hya-
line, homogeneous or lamellated. Cells ovoid to spherical, with one or
two golden-brown parietal chromatophores and with or without a
definite wall.

Reproduction by pyramidate, spherical, or ovoid zoospores with one
or two cilia.

The members of this division are the connection between the normally
motile and the highly differentiated sessile Phaeophyceae.

Order PHAEO CAPS ALES.

Cells generally organized into free-floating, spherical, ellipsoid, or
elongate colonies. Growth of colony taking place in all parts and not
restricted to the apical region. Cells variously shaped and with one or
two golden-brown chromatophores.

Eeproduction, aside from vegetative cell division, by the formation
of spherical to ovoid zoospores.

The order contains the single family of the Phaeocapsaceae and only
one member of the family, Phaeococcus, is found in the local flora.

PHAEOCOCCUS Borzi 1892.

Cells in spherical, ovoid, or irregularly shaped free-floating colonies
enclosed by a copious, hyaline, homogeneous or slightly lamellated,
gelatinous envelope. Cells ellipsoid to sub-spherical or spherical. Cell
number a multiple of two in young colonies, indefinite in older colonies.
Cells containing one or more golden-brown chromatophores, sometimes
with a red pigment spot.

Eeproduction by vegetative cell division or direct metamorphosis of
cell contents into biciliate ovoid to pyriform zoospores.

PHAEOCOCCUS PLANCTONICUS W. & G. S. West. PI. 14, Fig. 5.
Trans. Roy. Soc. Edinb. 41: 496, pi. 6, figs. 15-16. 1905.

Cells spherical to sub-spherical, generally distributed in small clumps
within a copious, hyaline, homogeneous or radially fibrillar, gelatinous
envelope. Number of cells in colony generally 16-64. Cells contain-

WISCONSIN PHTTOPLANKTON 77

ing 1-2 parietal, diseifonn to bell-shaped, golden-brown chromatophores
with, smooth or irregular margins. (Euplanktont).
Cells 7.2-9.6 /* in diam. ; colonies 50-250 //, in diam.

Carson (ss), Clear Crooked (c), Crawling Stone (rr),. Devils (1) (ss), Hill-
man (rr), Jennie (r), Mary (s), Mendota (sss), Pokegama (1) (rr), Sand
(4) (rr), Shell (ss), Silver (2) (s), White Sand (rr).

Division RHIZOCHRYSIDINAE.

Algae that are known in the rhizopodial stage only, although the
power to form a motile phase is presumed to be present. Cells solitary
or in small colonies, always free-floating. Cells with rhizopodial pro-
cesses and with or without a differentiated periplast. Cells with 1-2
golden-brown chromatophores, and with or without numerous vacuoles.

Reproduction by vegetative cell division.

This is an entirely artificial group where rhizopodial forms are placed
pending further elucidation of their life histories. Since the group
contains such doubtful forms no attempt has been made to differentiate
the orders and families.

KEY TO THE GENERA.

Cells solitary or in irregular colonies RHIZOCHBYSIS

Cells joined in a linear series to form colonies CHBYSIDASTBUM

KEIZOCHRYSIS Pascher 1913.

Cells free-floating, solitary or in colonies that are naked or enclosed
by a gelatinous sheath. Cells without a differentiation of the. periplast
but with few or numerous, delicate, pseudopodial processes. Cells with
one or two golden-brown chromatophores and numerous vacuoles, of
small size when united in colonies.

Rhizochrysis limnetica sp. nov. PI. 14, Fig. 6.

Cells solitary, free-floating, without a differentiation of the periplast
but with numerous spicule-like processes extending in all directions.
Cells approximately spherical, with one golden-brown chromatophore
and numerous vacuoles. (Euplanktont).

Diam. cells (without processes) 35-45 p..

Beasley (sss), Birch Island (rr), Crawling Stone (rr), Deer (rr), Diamond
(rrr), Half Moon (rr), Horse (rr), Kitten (sss), Lac du Flambeau (r), Long
(3) (sss), Marl (rrr), Nemahbin (ss), Oconomowoe (rr), Okauchee (rrr),

78 WISCONSIN PETTOPLANKTON

Otter (rrr), Pokegama (2) (r), Rainbow (1) (r), Round (3) (rr), Sand (4)
(sss), Taylor (r), Upper Nashotah (r), Wildcat (sss).

This species is quite unlike other members of the genus since the
processes are much more delicate and the cells larger.

CHRYSIDASTRUM Lauterborn 1913.

Cells joined to one another by pseudopodial processes and arranged
to form free-floating linear colonies of 2-16 cells that are not enclosed
by a gelatinous envelope. Cells spherical, with the periplast undiffer-
entiated but extending into several long, delicate, pseudopodia-like pro-
cesses. Chromatophore single, central, and laminate to band-shaped.

Reproduction unknown.

CHRYSIDASTRUM CATENATUM Lauterborn. PI. 14, Figs. 7-8.

in Pascher, D. Siisswasserfl. Deutschl., Qsterr. u. d. Schw. 2, Flagellatae 2: 91,
fig. 144. 1913.

Specific characters the same as those of the genus. (Euplanktont).
Diam. cells (without processes) 12-15 /A; (with processes) 45-60 /*.

Kitten (rr), Mud (2) (rr), Wildcat (rrr).

The cell shape is quite like that of Chrysamoeba but the definite or-
ganization into a linear colony and the single laminate chromatophore
are points of difference. The alga should also be compared with Rhizo-
chrysis planctonica Pascher.

WISCONSIN PHYTOPLANKTON 79

Class HETEROKONTEAE.

Cells microscopic or macroscopic ; free-floating, sessile, or epiphytic.
Cell shape spherical, ovoid, pyriform, cylindrical or irregular. Cells
solitary, in colonies of regular to irregular shape, or united to form
simple filaments. Colonies or individual cells with or without a gelat-
inous envelope. Chromatophores one to many, parietal, generally disci-
form, rarely laminate, yellowish-green in color and without a pyrenoid.
Assimilation product oil, never starch. Cells uninucleate or multinu-
cleate.

Asexual reproduction by vegetative cell division and a formation of
zoospores. Zoospores ovoid to pyriform, with two cilia of unequal
length and generally more than one yellowish-green chromatophore.

Sexual reproduction, insofar as known, isogamous, by zoogametes that
are similar in structure to the zoospores.

The various genera of the Heterokontae were formerly scattered
throughout the different families of the Chlorophyceae. The distinguish-
ing characteristics of this class are the yellowish-green chromatophores
without pyrenoids, with oil not starch the assimilation product; and
zoospores with two cilia of unequal length. There are three orders in
the class and representatives of all three are found in Wisconsin lakes.

KEY TO THE ORDERS.

Vegetative cells motile HETEBOCHLORIDALES

Vegetative cells immobile.

Cells solitary or in colonies, never in filaments HETEROCOCCAXES

Cells united to form simple filaments HETEBOTBICHALES

Order HETEROCHLORIDALES.

Cells solitary, free-swimming, ovoid to pyriform in shape. Motile
phase dominant, rarely metamorphosing over into an amoeboid or pal-
mella phase. Cells with two cilia of unequal length, one or more chro-
matophores of a yellowish-green color and without an eyespot. Assimi-
lation product leucosin or fat, never starch.

Asexual reproduction by vegetative division of cells.

Sexual reproduction unknown.

The order has but one family, the Chloramoebaceae, whose characters
are those of the order.

gO WISCONSIN PHYTOPLANKTON

CHLOROCHROMONAS Lewis 1913.

Cells solitary, generally free-swimming, very rarely amoeboid, some-
times attached to substratum by a posterior pseudopodia-like structure.
Cell shape pyriform to sub-ovoid, with an oblique depression at the
anterior end. Cilia two, at the anterior end of the cell and of unequal
length. Chromatophores two, yellowish-green in color, oblong with
rounded ends in front view, somewhat flattened in side view. Cells
with a single anterior vacuole, one nucleus, and without an eyespot.
Nutrition holophytic or saprophytic.

Reproduction by longitudinal fission when in the motile phase.

CHLOROCHROMONAS MINUTA Lewis. PI. 15, Figs. 1-3.
Arch. f. Protistenkunde 32: 254, pi. 12, figs. 1-24. 1913.

Characters as described above. (Euplanktont).
Cells 4.5-9.5 (av. 6.3) p, long, with an average breadth of 4.7 p..
Average length of longer cilium 12.5 //,, of the shorter 2.9 /JL.

Mendota.

This organism was first found by Lewis in a dish containing sections
of basswood (THia americana) that had been standing for some time in
a dish of tap water, which is drawn directly from Lake Mendota. I
have never noted the alga in plankton collections but have no doubt
but that a continued search will demonstrate its presence in Lake Men-
dota. During the past winter (1917-18) the alga appeared in an in-
fusion of fern leaves which had been standing for some time in tap
water. This shows that the original source of the alga was the water
with which the sections were moistened and not the Tilia.

Order HETEROCOCCALES.

Cells spherical, ovoid, saccate, or elongate cylindrical ; solitary or in
colonies of definite or indefinite shape; free-floating or sessile. Cells
of colonies embedded in a hyaline, gelatinous envelope or a tough elastic
membrane. Chromatophores one to many, yellowish-green to nearly
grass- green in color and with oil not starch the assimilation product.

Asexual reproduction by vegetative cell division and a formation of
zoospores with cilia of unequal length.

Sexual reproduction by a fusion of zoogametes that are similar in
structure to the zoospores is known in certain genera.

WISCONSIN PHTTOPLANKTON 81

KEY TO THE FAMILIES.

Cells epiphytic CHLOBOSACCACEAE

Cells free-floating.

Length of cells several times the diameter OPHIOCYTIACEAE

Length of cells less than twice the diameter.

Cells irregularly distributed throughout an ovoid

gelatinous envelope CHLOBOBOTRYDACEAE

Cells arranged about a common center within an

irregular gelatinous envelope BOTBYOCOCCACEAE

Family CHLOROSACCACEAE.

Cells epiphytic, solitary, gregarious, or embedded in an amorphous
gelatinous matrix. Chromatophores one to several, parietal, of a yel-
lowish-green color, with oil not starch the assimilation product.

Asexual reproduction by a formation of zoospores that presumably
have two cilia of unequal length.

Sexual reproduction by the fusion of isogamous zoogametes.

PERONIELLA Gobi 1887.

Cells epiphytic upon other algae, solitary or gregarious. Shape of
mature cells globular to ovoid, of young cells pyriform to ovoid. Cells
attached to substratum by a delicate hyaline stipe that is usually some-
what longer than the cell. Chromatophores one to two, pale yellowish-
green, without pyrenoids or starch and with oil as the assimilation
product.

Asexual reproduction by the division of cell contents into 2-4-8 uni-
ciliate (?) zoospores that are liberated by a lateral rupture of mother
cell wall. Zoospores swarming a short time and then coming to rest
upon substratum and developing into vegetative cells.

PERONIELLA PLANCTONICA G. M. Smith. PI. 15, Fig. 4.
Bull. Torr. Bot. Cl. 43: 476, pi. 25, fig. 15. 1916.

Cells broadly ovoid to pyriform, with a long, delicate, hyaline stipe
that is without a disc or other enlargement at the base. Chromato-
phores usually single, rarely two, pale yellowish-green, without pyre-
noids or starch. (Euplanktont).

Cells (without stipe) 6-9.5 /«, long; (with stipe) 15-18 /t. Stipe 8-10 ^
long, 1.2 p, broad.

In gelatinous envelope of Spkaerozosma filaments.

Devils (1) (rr).
6

82 WISCONSIN PHYTOPLANKTON

Family CHLOROBOTRYDACEAE.

Cells solitary or in free-floating colonies enclosed by a copious, homo-
geneous, gelatinous envelope. Colony generally with a small number
of cells and with cell number a multiple of two. Cells spherical, ovoid,
angular, or cylindrical ; with a firm cell wall that is sometimes impreg-
nated with a slight trace of silica ; and with one to many parietal, disci-
form, yellowish-green chromatophores without pyrenoids.

Asexual reproduction by vegetative cell division or a formation of
zoospores with two cilia of unequal length.

CHLOROBOTRYS Bohlin 1901.

Cells rarely solitary, generally in colonies of 2-4-8-16 or more em-
bedded in a copious, homogeneous, hyaline, gelatinous envelope. Cells
spherical to broadly ovoid, with a heavy wall that sometimes contains
a small amount of silica. A conspicuous red pigment spot present in
cells at times.

Reproduction by vegetative division of cells in three directions.

KEY TO THE SPECIES.

Cells ovoid, with few chromatophores C. L.IMNETICUS

Cells spherical, with numerous chromatophores C. REGULABIS

CHLOROBOTRYS REGULARIS (W. West) Bohlin. PI. 15, Fig. 10.

Bih. kgl. Sv. Vet.-Ak. Handl. 27, Afd. 3, No. 4: 34. 1901; W. & G. S. West,
Jour, of Bot. 41 : 78, pi. 447, figs. 7-10. 1903.

Chlorococcum regulare W. West, Jour. Roy. Micr. Soc. 1892: 737, pi. 10,
fig. 55. 1892.

Cells spherical to subspherical ; rarely solitary, generally in colonies
of 2-4-8-16 enclosed by a copious, hyaline, homogeneous, gelatinous
envelope. Cell wall thick, sometimes containing a trace of silica.
Chromatophores yellowish-green, disciform, parietal, 6-30 in each cell.
Cells at times containing a single conspicuous red pigment spot. (Ty-
choplanktont).

Diam. cells 10-27 p. Diam. colonies 35-90 /*.

North Turtle (rrr).

CHLOROBOTRYS LIMNETICUS G. M. Smith. PI. 15, Fig. 9.
Trans. Wis. Acad. Sci., Arts, & Lett. 191: 653, pi. 14, fig. 10. 1918.

Cells ovoid, irregularly distributed within a homogeneous, hyaline,
gelatinous envelope. 10-30 cells in a colony. Chromatophores 3-4,

WISCONSIN PHYTOPLANKTON 83

pale yellowish-green, disciform, parietal, and without pyrenoids. (Eu-
planktont) .

Cells 5-6 fji broad, 6-8 ^ long. Diam. colonies 40-200 //,.

Camp (IT).

Family BOTRYOCOCCACEAE,

Cells always in free-floating colonies of definite or indefinite shape.
Number of cells in colony generally indefinite, few or many. Colony
enclosed by an envelope that may be hyaline or Colored, gelatinous or
leathery. Cells usually ovoid, rarely spherical; with 1-2 parietal,
laminate to disciform, yellowish-green to nearly grass-green chromato-
phores without pyrenoids and with oil as the assimilation product.

Asexual reproduction by vegetative cell division. Zoospore forma-
tion or sexual reproduction unknown.

BOTRYOCOCCUS Kiitzing 1849.

Cells in free-floating colonies of indefinite shape. Cells closely ap-
posed to one another and enclosed by a gelatinous or tough membrane
that is sometimes wrinkled and folded. Colonies generally with cells
in several aggregates that are connected by broad or delicate strands
of the colonial integument. Cell shape spherical, ovoid, or cuneate.
Groups of cells arranged in a single layer around a common center, or
irregular in arrangement. Chromatophore single, parietal, laminate
to disciform, yellowish-green to nearly grass-green in color and without
a pyrenoid.

Reproduction by vegetative division of cells.

KEY TO THE SPECIES.

Cells held together by a thin gelatinous envelope B. SUDETICUS

Cells held together by an irregular tough membrane.

Membrane completely enclosing cells B. BBATJNII

Membrane covering base only of cells B. PBOTUBERANS var. MINOE

BOTRYOCOCCUS SUDETICUS Lemmermann. PI. 15, Fig. 8.

Forschungsbr. a. d. Biol. Stat. zu Plon. 4: 111, figs. 6-7. 1896.

Botryococcus Braunii G. S. West non Kiitzing, Brit. Freshw. Algae 237, figs.
306A-106B. 1904; G. M. Smith, Trans. Wis. Acad. Sci., Arts, & Lett. 18a: 545
1916.

Colonies free-floating ; spherical or irregular ; with cells held in botry-
oidal clusters by a hyaline gelatinous envelope and frequently joined
to one another by broad or narrow strands of the gelatinous envelope.
Cells spherical to subspherical, 16-32 or more in each botryoidal group,

84 WISCONSIN PHYTOPLANKTON

and arranged around a common center. Chromatophore single, cup-
shaped to disciform, without a pyrenoid. (Euplanktont).

Diam. cells 6-13 p..

Clear (rr), Waubesa (rrr).

This is the B. Braunii Ktz. of the preliminary list, the identification
being based upon G. S. West's description of B. Braunii in his British
Freshwater Algae. Dr. West has since informed me that the Ineffigiata
neglecta of that work is B. Braunii Ktz. and the B. Braunii described
therein is B. sudeticus Lemm.

BOTRYOCOCCUS BRAUNII Kutzing. PI. 15, Fig. 5.

Species algarum 892. 1849; Fresenius, Abh. Senckenb. Naturf. Ges. 2: 239,
pi. 11, figs. 27-33. 1858.

Ineffigiata neglecta W. & G. S. West, Jour. Roy. Micr. Soc. 1897: 503. 1897;
Jour, of Bot. 41: 80, pi. 447, figs. 1-6. 1903.

Cells joined in small free-floating colonies of irregular shape that are
without a conspicuous gelatinous envelope but completely enclosed by
a tough, elastic, hyaline to orange colored membrane that is pro-
duced into irregular wrinkles, folds, and spines. Colonies frequently
united to form compound colonies by long delicate projections of the
colonial envelope. Cells ovoid or ellipsoid in shape and forming a
single layer around a central cavity. Chromatophore single, cup-shaped
to laminate, yellowish-green to nearly grass-green in color, without a
pyrenoid. Assimilation product a reddish oil that may color the whole
colony a brick red. (Facultative planktont).

Cells 3.5-5.5 /* broad, 5.7-10.5 /i long. Simple colonies up to 100 p.
in diam. ; compound colonies up to 1.5 mm.

Balsam (rr), Bear (3) (rr), Bear Trap (rrr), Beaver (2) (rr), Beaverdam
(ss), Birch Island (rrr), Birch (2) (rr), Boulder (rrr), Browns (sss), Camp
(rrr), Carson (r), Center (r), Chain (rrr), Chetac (rr), Clam (rrr), Clare
(r), Cochrane (rrr), Crawling Stone (rr), Crooked (sss), Deer (rr), Delavan
(rrr), Des Moines (rr), Devils (1) (r), Devils (2) (r), Devils (3) (rrr),
East (rr), Elizabeth (rr), Green (1) (rr), Green (2) (rrr), Grindstone (r),
High (rr), Horse (rrr), Horseshoe (1) (rr), Island (rr), Jennie (rr), Jones
(rrr), Kawaguesaga (rrr), Kegonsa (r), Kimball (rrr), Kitten (rrr), Lac
Court Oreilles (sss), Lac du Flambeau (rrr), Little Bass (1) (rrr), Little
Butternut (rrr), Little Crooked (rrr), Little Doctor (rr), Little Rice (1) (rr),
Long (1) (rrr), Lower Nashotah (r), Lynx (rr), Mary (sss), Mendota (ss),
Mercer (rrr), Mill (rrr), Monona (sss), Mud (3) (rrr), Mud Hen (sss), Nancy
(r), Nicaboyne (rrr), No Mans (rr), Paddock (r), Palmer (rrr), Pardee (sss),
Pike (rrr), Pokegama (1) (rrr), Pokegama (2) (rrr), Poor Farm (rrr), Re-
serve (rr), Rice (1) (rr), Round (2) (rrr), St. Croix (rrr), Sand (1) (r),
Sand (2) (rr), Sand (3) (rr), Sand (4) (rrr), Shell (rr), Silver (2) (r),
Sishebogema (rr), South Turtle (rr), Spirit (rrr), Tied Canoe (rrr), Travis
(rrr), Upper Nashotah (sss), Wapagossett (rr), Waubesa (r), White Ash
(rrr), Whitefish (rrr), Wildcat (rrr), Winnebago (rrr), Wolf (rrr).

WISCONSIN PHYTOPLANKTON 85

BOTRYOCOCCUS PROTRUBEBANS var. MINOR G. M. Smith. PL 15, Figs. 6-7.
Trans. Wis. Acad. Sci., Arts, & Lett. IV: 652, pi. 14, figs. 6-7. 1918.

Cells in colonies of 4-8-16 or more held together by a tough gelat-
inous membrane. Colonies frequently joined to one another by long
hyaline strands of the colonial envelope. Cells ovoid to cuneate-ovoid,
with their bases embedded in the colonial envelope and their apices
not enclosed by the envelope. Cells arranged in a single layer around
a central cavity. Chromatophores single, yellowish-green, laminate,
occupying the median portion of the cell. (Euplanktont).

Cells 8-9.5 p. long, 5-6.5 p. broad at the widest part.

Diamond (rrr), George (aa), Hillman (rr), Lindy (rr), Oak (ss), Pardee
(rr), Sanford (rr), South Crab (s).

This species is distinguished from the foregoing by the smaller num-
ber of cells in the colony and the projection of the apex of the cells
through the colonial integument.

Family OPHIOCTTIACEAE.

Cells sessile or free-floating, solitary or colonial. Length of cells
generally several times the breadth. Cells straight, curved, sigmoid, or
spiral; with or without terminal spines. Chromatophores yellowish-
green ; annular, parietal and few in number ; or discif orm, parietal and
numerous ; without pyrenoids and with oil as the assimilation product.

Asexual reproduction by division of cell contents to form 4-16 aplano-
spores or 2-8 biciliate zoospores with cilia of unequal length.

Sexual reproduction unknown.

OPHIOCYTIUM Nageli 1849.

Cells free-floating or epiphytic, solitary or colonial ; straight, arcuate,
sigmoid, or spiral elongate cylinders with rounded or capitate ends
that may be apiculate or attenuated into a single spine. Chromato-
phores pale yellowish-green, H-shaped in optical cross section, without
pyrenoids and with oil as the assimilation product. Cells coenocytic.
Cell wall consisting of a homogeneous cap at one end and with the re-
maining portion of the wall composed of a number of laminate layers.

Asexual reproduction by division of cell contents to form 4—16 aplano-
spores or 2-8 biciliate zoospores with cilia of unequal length.

gg WISCONSIN PHYTOPLA.NKTON

KEY TO THE SPECIES.

Poles of cells without spines O. PABVULTIM

Poles of cells with spines °- CAPITATUM

OpmocYTroM PARVULUM (Perty) A. Braun. PI. 15, Fig. 11.
Alg. unicell. 55. 1855; Lemmermann, Hedwigia 38: 33, pi. 4, figs. 30-33. 1899.

Cells cylindrical, several times as long as broad ; straight, arcuate, or
spiral; poles rounded and without spines. Chromatophores several,
H-shaped in cross section, pale yellowish-green. Oil droplets rarely
present. ( Ty choplanktont ) .

Cells 3-9 /i broad.

Fishtrap (rrr).

OPHIOCYTIUM CAPITATUM Wolle. PI. 15, Figs. 12-13.
Freshw. Algae of U. S. 176, pi. 158, figs. 3-7. 1887.

Cells solitary ; arcuate, sigmoid, or spiral cylinders with poles rounded
and the same size as or slightly larger than the median portion of the
cell. Length of cell 5-10 times the breadth. Poles of cells with a
single short, straight, or slightly curved spine. ( Ty choplanktont) .

Cells 5-10 /x broad, up to 85 p. long. Spines 5-7 /* long.

Tied Canoe (rrr).

var. LONGISPINUM (Mobius) Lemmermann. PI. 15, Figs. 14-16.
Hedwigia 38: 32, pi. 4, figs. 21-25. 1899.

Cells cylindrical ; straight, arcuate, or spirally twisted, with a single
long spine at each pole that is nearly as long as the cell. (Euplank-
tont).

Diam. cells 4.5-6 //,. Length of spines 16-50 p..

George (rr), Loon (rr).

Order HETEROTRICHALES.

Cells in simple, unbranched filaments; with or without a gelatinous
envelope. Cell wall firm, fairly thick, lamellated in structure and
breaking down into H-shaped pieces at the time of reproduction. Chro-
matophores few to several, yellowish-green, disciform, and parietal.
Cells usually uninucleate. Assimilation product oil, not starch.

Asexual reproduction by the formation of aplanospores or by zoo-
spores with two cilia of unequal length.

WISCONSIN PHYTOPLANKTON 87

Sexual reproduction by the fusion of isogamous zoogametes.
There is but one family in the order, the Tribonemaceae, whose char-
acters are the same as those of the order.

TRIBONEMA Derbes and Solier 1856.

Cells in simple unbranched filaments destitute of an enveloping gelat-
inous sheath. Cells cylindrical or barrel-shaped, with flattened end
walls. Cell wall frequently of considerable thickness and laminate in
structure. Chromatophores two to several, yellowish-green, disciform,
parietal, without starch and with oil as the assimilation product.

Asexual reproduction by aplanospores and biciliate zoospores that
have cilia of unequal length. The cell wall pulling apart and breaking
down into H-shaped pieces at the time of reproduction.

Sexual reproduction by the fusion of isogamous zoogametes.

TRIBONEMA MINUS (Wille) Hazen. PL 15, Figs. 17-18.
Mem. Torr. Bot. Cl. 11: 185, pi. 25, figs. 7-8. 1902.

Filaments generally forming a floccose yellowish to greenish mass.
Cells cylindrical or slightly swollen in the median portion, generally
2-4, rarely 6, times as long as broad. Chromatophores 2-4, yellowish-
green, disciform, parietal, generally in pairs. (Facultative planktont).

Cells 5-6 p. broad, 10-35 p. long.

Green (1) (rrr), Mendota (s).

Members of this genus are frequently found in ditches but seldom in
lakes. During the past season T. minus has appeared in considerable
quantity in the plankton of Lake Mendota, although previous to this
time the alga has not been found in the plankton. A similar sudden
appearance of T. bombycina forma depauperata Wille, a form closely
related to T. minus, has been noted in the plankton of Danish lakes by
Wesenberg-Lund (Studier over de danske soers Plankton p. 100.
Kjobenhavn, 1904).

•

\0'

-7! •

.

V/4

WISCONSIN PHYTOPLANKTON

Class CHLOROPHYCEAE.

Cells with the coloring matter restricted to definite bodies that are
grass-green in color (chloroplasts). Cells free-floating, sessile, epi-
phytic, epizootic, or endophytic ; solitary, in microscopic to macroscopic
colonies of definite or indefinite shape that are naked or enclosed by a
hyaline to colored, homogeneous or lamellated, firm or gelatinous en-
velope. Colonies with all of the cells morphologically alike or differen-
tiated. Colonies growing in all directions; forming simple, laminated,
or parenchymatous plates; or developing into simple or branched fila-
ments. Cells motile throughout the whole life history, for a portion
of it, or immobile at all times. Cells variously shaped ; spherical, hemi-
spherical, ovoid, ellipsoid, spindle-shaped, acicular, renifonn, angular,
irregular, cylindrical, conical, simple to branching tubular, or con-
stricted to form two symmetrical halves of various shapes. Cells con-
taining one or more disciform, laminate, cup-shaped, astral, ribbon-like,
or reticulate chloroplasts that are parietal, axial, or central in position
and have one or more centers for the synthesizing of starch (pyrenoids) .
Assimilation product oil in a few cases. Cells uninucleate or multinu-
cleate (coenocytic) ; containing a central vacuole, numerous small vacu-
oles, or without vacuoles. Contractile vacuoles chiefly confined to the
motile genera.

Asexual reproduction by vegetative cell division, aplanospores, zoo-
spores, or akinetes.

Sexual reproduction by isogamous or heterogamous zoogametes, isoga-
mous aplanogametes, or heterogamous motile antherozoids and immobile
oospheres. Zygotes germinating immediately, or after a period of rest ;
with a direct or an indirect germination into the plant body.

KEY TO THE DIVISIONS

Sexual or asexual reproductive bodies with 2-4 cilia of equal length. . ISOKONTAE
Sexual or asexual reproduction by non-ciliate reproductive bodies AKONTAE

Division ISOKONTAE.

Cells solitary or in colonies and showing the same great range of
Tariation in shape, organization of the colony, interior structure, and
method of reproduction noted in the description of the class.

Included in this division is the important plankton family of the
Autosporaceae where no motile phase of reproduction is known. The

WISCONSIN PHYTOPLANKTON 89

close phylogenetic connection between the Autosporaceae and the other
members of the Protococcales is, however, perfectly evident.

KEY TO THE ORDERS.

Cilia normally present throughout the whole life cycle VOLVOCALES

Cilia present at time of reproduction only.
Cells in simple or branched filaments.

Cells uninucleate, with a single laminate chloroplast ULOTRicHALjca

Cells multinucleate, with one or more chloroplasts . . SiPHONOCLADiALEa
Cells solitary or in simple colonies, generally of microscopic

size PBOTOCOCCALES

Order VOLVOCALES.

Cells normally ciliate and motile during the vegetative phases of the
life cycle. Solitary or organized into colonies of definite form that
generally contain a definite number of cells. Protoplasts rarely naked,
usually with a differentiated outer cellulose covering that may be par-
tially gelatinized. Shape of protoplast spherical, ovoid, disciform,
pyramidate, or irregularly radiate. Cells with a single cup-shaped to
irregular chloroplast, with or without pyrenoids ; with 2-4 cilia at the
anterior end ; generally with a disciform to bacillif orm eyespot, two to
several contractile vacuoles, and one nucleus. Palmella stages fre-
quently arising in the unicellular members.

Asexual reproduction by division of cell contents into 2-16 zoospores ;
or a development of special, or all cells of the colony into autocolonies.

Sexual reproduction by isogamous zoogametes; heterogamous zoo-
gametes ; or small motile antherozoids and large immobile oospheres.

Many hold with G. S. West (Algae 151, 1916) "that it is very doubt-
ful if the Volvocineae have sufficient claims to be removed from the
Protococcales and elevated to a group of equal rank (the ' Volvocales') ".
There is a very close relationship between the "palmella" stage of
various unicellular Volvocales and the family Palmellaceae of the Pro-
tococcales. This represents to me, however, a close phylogenetic rela-
tionship between the two and not a justification for uniting in the same
order forms with mobile vegetative cells and those which are immobile.

KEY TO THE FAMILIES.

2 cilia at the anterior end of cells.

Cells solitary CHLAMYDOMOIT ADACEAE

Cells in definite coenobia VOLVOCACEAE

4 cilia at the anterior end of cells CAOTERIACEAE

90 WISCONSIN PHYTOPLANKTON

Family CHLAMYDOHONADACEAE.

Cells normally solitary and motile during the vegetative phases of
the life history. Spherical, ovoid, cylindrical, sub-acicular, compressed,
or quadrately projected. Chloroplast cup-shaped to laminate, lateral
or posterior in position, with or without pyrenoids. Cells uninucleate,
with or without an eyespot, with two cilia of equal length that generally
have two contractile vacuoles at their base. Cells at times becoming
immobile and developing into amorphous colonies enclosed by a wide
gelatinous envelope.

Asexual reproduction by the division of cell contents to form 2-16
biciliate zoogametes.

Sexual reproduction by the fusion of isogamous zoogametes.

CHLAMYDOMONAS Ehrenberg 1832.

Cells normally solitary and motile ; though capable of coming to rest,
losing the cilia, developing a gelatinous envelope and dividing vegeta-
tively to form colonies containing an indefinite number of cells. Cells
spherical, fusiform, ovoid, pyrif orm, or ellipsoid ; with two cilia of equal
length at the anterior end. Chloroplast typically cup-shaped, posterior,
and with one pyrenoid. Cells uninucleate, generally with two con-
tractile vacuoles at the base of the cilia; with or without an eyespot
which, when present, lies in the anterior portion of the cell.

Asexual reproduction by division of cell contents to form 2-16 bicili-
ate zoospores.

Sexual reproduction isogamous, by the division of cell contents into
8-64 zoogametes that fuse in pairs to form smooth-walled or sculptured
zygotes.

KEY TO THE SPECIES.

Cells spherical.

Anterior end without a beak C. GLOBOSA

Anterior end with a pronounced beak C. EPIPHYTICA

Cells ovoid.

Chloroplast cup-shaped and basal C. SNOwn

Chloroplast laminate, lateral, or basal C. DINOBRTONI

CHLAMYDOMONAS GLOBOSA Snow. PI. 16, Fig. 8.
Bull. U. S. Fish Comm. 22: 389, pi. 1, figs. HP-HP. 1903.

Cells spherical or slightly ellipsoid, without an anterior beak. Chloro-
plast cup-shaped, occupying the greater portion of the cell, with one
pyrenoid at the posterior end. Eyespot present, small, generally in the
middle third of the cell. Cilia slightly longer than the cell and with a

WISCONSIN PHTTOPLANKTON 91

single contractile vacuole at their base. Palmella stages frequent and
usually containing 4^-8 cells. (Euplanktont).
Cells 5-10 p broad.

Crawling Stone (rr).

Chlamydomonas epiphytica sp. nov. PI. 16, Figs. 11-13.

Cells spherical to pyriform, with a very pronounced anterior beak.
Chloroplast cup-shaped, forming a thin layer next to the cell wall, with
a single pyrenoid at the posterior end. Eyespot conspicuous, disciform,
at the anterior end of the cell. Cilia more than twice as long as the
cell. Cells frequently coming to rest in the gelatinous envelope of
Microcystis colonies but not losing the eyespot and usually retaining
the cilia. (Euplanktont).

Cells 7-8 ju, broad, 8-9 /* long ; cilia 20-25 /* long.

Elizabeth (s), Mary (sss).

The alga is frequently found in the gelatinous envelope of Microcystis
colonies and suggests an epiphytic diaracium but the presence of cilia
shows that it is a Chlamydomonas.

CHLAMYDOMONAS SNOWH Printz. PI. 16, Figs. 9-10.

Skr. Vidensk.-Selsk. 1 Kristiana, Mat.-Naturv. Kl. 19131: No. 6: 18. 1914.

Chlamydomonas communis Snow, Bull. U. S. Fish Comm. 22: 388, pi. 1,
figs. IP-IP. 1903.

Cells motile but frequently forming palmella stages containing a
considerable number of cells. Cell shape ovoid to ellipsoid, with a very
inconspicuous anterior beak. Chloroplast cup-shaped, massive in the
posterior portion, with one pyrenoid at the center of the cell. Cilia
slightly longer than the cell; eyespot inconspicuous, variable in posi-
tion. (Facultative planktont).

Cells 6.5-8 /JL broad, 10-15 /* long.

Nancy (rr).

Chlamydomonas dinobryoni sp. nov. PI. 16, Figs. 5-7.

Cells rarely free-swimming, generally in large numbers and filling
the empty receptacles of Dindbryon colonies. Cells small, ovoid to pyri-
form in shape, without an anterior beak; with two short cilia at the
anterior end. Chloroplast disciform to hemispherical, basal or lateral
in position, containing a pyrenoid. Eyespot and contractile vacuoles
not observed. (Euplanktont).

Cells 2-3 ju, broad, 3.5-5 p long; cilia 6-8 ^ long.
Lac du Flambeau (ss), Long (3) (s), Pokegama (2) (r).

92 WISCONSIN PHYTOPLANKTON

Many of the empty Dinobryon receptacles in these three connecting
lakes were filled with a minute green organism. These had cilia, even
when in the receptacle, and on the slightest crushing of the receptacle
began swimming around outside of it. Since cilia are constantly pres-
ent the alga is a Chlamydomonas and not one of the Palmellaceae col-
lected at the time of reproduction.

Family CARTERIACEAE.

Cells normally motile and with four cilia of equal length at the an-
terior end. Solitary, or in coenobia containing a definite number of
cells. Cell shape spherical, ovoid, ellipsoid, cardioid, pyriform, or
lenticular. Cells enclosed by a definite wall, and with or without a
cup-shaped to lenticular chloroplast that is with or without pyrenoids.
Eyespot generally present, conspicuous, and at the anterior end of the
cell. Cells frequently with contractile vacuoles at the base of the
cilia. Palmella stages known in the solitary members of the family.

Asexual reproduction by the division of cell contents into 2-16 tetra-
ciliate zoospores or into autocolonies.

Sexual reproduction isogamous, by a fusion of tetraciliate zoogametes.

CARTERIA Diesing 1866.

Cells solitary, generally motile throughout the vegetative phases of
the life cycle. Spherical, ovoid, ellipsoid, or cardioid in shape; with
four cilia of equal length at the anterior end. Cell contents consisting
of a single cup-shaped chloroplast that contains a pyrenoid; one eye-
spot; and two contractile vacuoles at the base of the cilia. Palmella
stages containing an indefinite number of cells are found at times.

Asexual reproduction by division of cell contents to form 2-8 tetra-
ciliate zoospores.

Sexual reproduction by the division of cell contents to form 4-64
tetraciliate zoogametes that fuse in pairs to form zygotes with smooth
or sculptured walls.

KEY TO THE SPECIES.

Cells ellipsoid C. KLEBSII

Cells cardioid C. COBDIFORMIS

CARTERIA CORDIFORMIS (Carter) Diesing. PI. 16, Fig. 1.

Sitzbr. d. k. Ak. d. Wiss. Wien, Mat.-Naturw. Kl. 521: 356. 1866; Dill, Jahrb. f.
wlss. Bot. 28: 353, pi. 5, figs. 42-44. 1895.

Cells cardioid in shape with four cilia at the base of the apical de-
pression. Chloroplast cup-shaped, fairly massive, with a single pyre-

WISCONSIN PETTOPLANKTON 93

noid in the posterior region. Cells with two contractile vacuoles at
the base of the cilia and with a disciform eyespot in the upper third
of the cell. (Tychoplanktont).
Cells 9-16 IL broad, 12-20 /t long.

Crawling Stone (rrr).

CABTERIA KLEBSII (Dangeard) Dill. PI. 16, Figs. 2-4.

Jahrb. f. wiss. Bot. 28: 353. 1895; Printz, Skr. Vidensk.-Selsk. Kristiana, Mat.-
Naturv. Kl. 19131: No. 6: 13. 1914.

Pithiscus Klebsii Dangeard, Ann. Sci. Nat. 7 Ser. Bot. 7: 137, pi. 12, figs.
1-6. 1888.

Cells solitary, ellipsoid to ellipsoid-cylindrical, with a more or less
prominent beak at the anterior end. Chloroplast cup-shaped, massive,
with a large pyrenoid at the posterior end. Cells without an eye-spot
and with two contractile vacuoles at the base of the cilia. Cilia about
twice as long as the cells. Palmella stages containing many cells at
times. (Tychoplanktont).

Cells 5-10 /i broad, 8-16 p long.

Pokegama (1) (r).

Family VOLVOCACEAE.

Cells always motile and in coenobia of definite shape that contain a
definite or an indefinite number of cells. Colonies enclosed in a homo-
geneous, hyaline, gelatinous envelope. Cells of colony all alike or dif-
ferentiated into vegetative and reproductive cells. Vegetative cells
spherical, ellipsoid, pyrif orm or disciform ; with or without connecting
cytoplasmic processes; always biciliate. Chloroplasts generally cup-
shaped and containing one pyrenoid. Vegetative cells usually with an
eyespot and two contractile vacuoles.

Asexual reproduction by the division of all or certain of the cells in
the colony to form autocolonies.

Sexual reproduction by a division of all cells in the colony to form
isogamous zoogametes or heterogamous zoogametes of slightly different
size; or the formation of motile antherozoids from certain cells and
large immobile oospheres from others. Zygotes with smooth or sculp-
tured walls.

94 WISCONSIN PH7TOPLANKTON

KEY TO THE GENERA.

Colony with cells in a flat plate GONIUH

Colony with cells forming a hollow sphere.

Cells mutually compressed PANDOBINA

Cells some distance from one another.

Asexual reproduction by division of all cells in colony EUDOBINA

Asexual reproduction by division of special cells.

At least half of cells capable of forming autocolonies. . .PLEODOBINA
Only a few cells capable of forming autocolonies VOLVOX

GONIUM Mueller 1773.

Colonies of 4-8-16 cells arranged in a flat quadrangular plate and
embedded in a common gelatinous matrix or connected by broad gelat-
inous strands. Cells ovoid to pyriform, with a single cup-shaped chlor-
oplast containing one pyrenoid. Each cell with two cilia of equal
length, contractile vacuoles at the base of the cilia, and an eyespot.
Four- and eight-celled colonies with the cilia on the same side ; sixteen-
celled colonies with the four central cells having their cilia on the same
side and the twelve marginal cells with radially arranged cilia.

Asexual reproduction by simultaneous division of all cells in the
colony to form autocolonies, or by a formation of 2-4 zoospores in each
cell.

Sexual reproduction isogamous, by a fusion of biciliate zoogametes.

GONIUM PECTORALE Mueller. PI. 16, Figs. 14-15.

Vermium terrestrium et fluviatilium etc. 1: 60. 1773; Migula, Bot. Cent. 44:
72, pi. 2, figs. 1-8. 1890; Harper, Trans. Am. Micr. Soc. 31: 65, pi. 5, figs. 1-19,
23. 1912.

Colonies containing 4—8—16 cells. Usually with 16 cells arranged in
two concentric series in a flat plate with truncate corners. Cells con-
nected with one another by broad, hyaline, gelatinous processes and
with open spaces between the processes; or with processes indistinct
and the whole colony embedded in a homogeneous, gelatinous matrix.
Outer ring with twelve cells whose long axes lie parallel to the plane
of the coenobe. Inner ring of four cells with a large open space at the
center and their long axes perpendicular to plane of the coenobe. Cells
ovoid to pyriform, with two cilia at the anterior end ; a posterior massive
cup-shaped chloroplast ; an anterior eyespot ; and two contractile vacu-
cles at the base of the cilia. (Tychoplanktont) .

Cells 7-11 p. broad, 10-25 /* long.

Beaver dam (rrr), Clam (rrr), Duck (rr), Fowler (rrr), Island (r), Ke-
gonsa (rrr), Long (1) (rrr), Mendota (rrr), Number One (rr), Pike (rrr),
Poplar (rrr).

WISCONSIN PHYTOPLA.NKTON 95

PANDOEINA Bory 1824.

Colonies always motile, spherical to subspherical, containing 4-8-16-
32 cells mutually compressed to form a hollow sphere with a small
open space at the center. Colony enclosed by a fairly copious, firm,
hyaline, homogeneous, gelatinous envelope. Cells pyriform to angular
by mutual compression, with pointed ends toward the center of the
colony; biciliate at the flattened distal end, the two cilia lying close
together while passing through the colonial envelope and then becom-
ing markedly divergent. Chloroplast single, massive, cup-shaped, with
one pyrenoid at the base. Eyespot single, generally on distal face of
the cell. Cells with a definite wall and two contractile vacuoles at the
base of the cilia.

Asexual reproduction by simultaneous division of all cells of the
colony to form autocolonies that are liberated by a gelatinization of the
colonial envelope.

Sexual reproduction by a division of each cell of the colony into
16-32 zoogametes. Zoogametes showing indications of heterogamy in
the slight difference in size and motility of the pairs that fuse to form
the smooth walled zygote.

PANDORINA MORUM Bory. PI. 16, Figs. 16-17.

Encyc. meth. hist. nat. de Zoophytes 2: 600. 1824; G. S. West, Brit. Freshw.
Algae 193, figs, 76A-76H. 1904.

Colonies generally 16-celled and as described above. (Facultative
Planktont).

Cells 8-16 /*, broad ; colonies 20-45 p. broad.

Bear Trap (rrr), Blake (rrr), Camp (rr), Center (cc), Chetac (rr), Chetek
(ss), Deer (rrr), Duck (ss), East (rrr), Fowler (rr), Grindstone (s), Hillman
(rr), Hooker (s), Kegonsa (sss), Lac Court Oreilles (ss), Lindy (rr), Little
Bass (2) (rr), Little Butternut (rr), Little Rice (1) (r), Little Wood (rrr),
Long (1) (rrr), Loveless (rr), Lower Nashotah (rr), Lower Nemahbin (rr),
Lower Turtle (sss), Mendota (ss), Monona (s), Mud (1) (rrr), Nagawicka
(BS), Nicaboyne (r), No Mans (rr), Number One (rr), Oconomowoc (rrr),
Okauchee (rrr), Pokegama (3) (r), Prairie (r), Rice (1) (r), St. Croix (rr),
Sishebogema (rr), South Turtle (sss), Upper Nashotah (rr), Upper Nemahbin
(rr), Upper Turtle (rr), Waubesa (ss), Whitefish (rr), Winnebago (rr).

EUDORINA Ehrenberg 1832.

Colonies always motile, spherical or slightly elongate, of 16-32-64
cells lying some distance from one another and arranged to form a
hollow sphere near the periphery of the homogeneous, hyaline, gelat-
inous envelope. Cells spherical, with or without a beak at the point
of origin of the two cilia. Cilia parallel while passing through the

96 WISCONSIN PHYTOPLANKTON

colonial envelope and then widely divergent. Chloroplast single, cup-
shaped, filling practically the whole cell and generally with several pyre-
noids. Cells with a firm wall, one or two anterior contractile vacuoles,
and a single conspicuous eyespot near the base of the cilia.

Asexual reproduction by a simultaneous division of all cells to form
autocolonies which are liberated by a rupture of the colonial envelope.

Sexual reproduction heterogamous, dioecious, with all cells of a col-
ony developing into large immobile oospheres or plate-like masses of
32-64 fusiform antherozoids; or monoecious with four cells forming
antherozoids and the remainder oospheres. Zygote smooth-walled.

EUDORINA ELEGANS Ehrenberg. PI. 19, Fig. 1.

Abh. d. kgl. Ak. d. Wiss. zu Berlin 1831: 78, pi. 2, figs. KU-lOo. 1832; G. S.
West Brit. Freshw. Algae 194, figs. 77A-77F. 1904.

Colonies generally 32-celled and as described above. (Facultative
planktont).

Cells 12-24 p. in diam. ; colonies 50-200 /* in diam.

Balsam (rrr), Bear (3) (ss), Bear Trap (r), Beaver dam (sss), Big Butter-
nut (rr), Birch (2) (ss), Birch Island (rr), Boulder (cc), Bryer (rr), Camp
(cc), Catherine (ss), Center (sss), Chetac (ss), Chetek (s), Clam (rr), Crawl-
ing Stone (rrr), Delavan (sss), Devils (1) (aa), Diamond (sss), Duck (ss),
Dunham (ss), Dutchmans (rrr), Elizabeth (rr), Fish (sss), Fowler (rr),
Granite (ss), Green (2) (rr), Grindstone (rrr), Hillman (rr), Hill (rrr),
Hooker (rr), Horseshoe (1) (rr), Horseshoe (2) (rrr), Howey (rrr), Island
(ss), Jennie (r), Kawaguesaga (rr), Kegonsa (ss), Lac Court Oreilles (rr),
Lac la Belle (rr), Lake of the Woods (s), Lindy (rr), Little Butternut (rr),
Little Wood (rrr), Long (3) (rrr), Loon (rr), Lower Nemahbin (rrr), Lower
Turtle (r), Lynx (rr), Meronk (rrr), Middle McKenzie (rr), Nancy (rr),
Nicaboyne (ss), No Mans (rr), North Turtle (ss), North Twin (rr), Number
One (rr), Okauchee (rr), Paddock (cc), Pine (2) (rrr), Pike (r), Pokegama
(2) (rr), Pokegama (3) (ss), Poplar (rr), Prairie (ss), Reserve (rr), Rain-
bow (rrr), Rice (1) (ss), Rooney (rr), Round (1) (r), Round (2) (rr),
Round (3) (sss),, Sand (1) (sss), Sand (4) (rr), Silver (2) (c), Sishebogema
(ss), South Crab (rr), South Turtle (sss), Spirit (sss), Squirrel (SB), Tender-
foot (rrr), Travis (rrr), Vermilion (rr), Waubesa (sss), White Sand (rrr).

PLEODORINA Shaw 1894.

Colonies always motile; spherical to sub-spherical, with 32-128 cells
lying some distance from one another just within the periphery of the
homogeneous, hyaline, gelatinous, colonial envelope and not connected
by cytoplasmic strands. Cells differentiated into those that are purely
vegetative in character and those capable of dividing to form daughter
colonies. All but four cells of the colony reproductive or about half
reproductive and half vegetative. Cells spherical to ovoid in shape.
Vegetative cells with a cup-shaped chloroplast containing one pyrenoid ;

WISCONSIN PHYTOPLANKTON 97

a large anterior eyespot ; two cilia of equal length with two contractile
vacuoles at their base. Reproductive cells at first like the vegetative
cells, later with a more massive chloroplast that eventually contains
several pyreuoids. The eyespot and cilia of reproductive cells disap-
pearing when they are mature.

Asexual reproduction by a simultaneous division of all reproductive
cells to form autocolonies.

Sexual reproduction (which has been observed in one species only)
heterogamous, dioecious, by a division of all reproductive cells to form
plates of 64-128 biciliate, fusiform antherozoids ; or a development of
reproductive cells into oospheres. Zygotes smooth-walled.

The validity of this genus has been questioned by many and the view
put forward that the alga is but a stage in the life history of Eudorina.
Grove (New Phytol. 14: 169-182. 1915) gives a full discussion of the
literature of Pleodorina. Although Eudorina elegans is found in a
large number of Wisconsin lakes, Pleodorina has been found in but
three of them. If Pleodorina is a developmental stage of Eudorina, it
is strange that, the "Pleodorina" stage has not been observed with
greater frequency. The young colonies look very much like those of
Eudorina and it is probably on this account that the two have been
confused.

PLEODORINA CAT.TFORNICA Shaw. PI. 17, Figs. 1-3.
Bot. Gaz. 19: 279, pi. 27, figs. 1-9. 1894.

Colonies containing 64-128 cells. Cells usually spherical and about
half vegetative and half reproductive. Reproductive cells becoming
4-5 times broader than the vegetative cells. (Facultative planktont).

Vegetative cells 6-14 p. in diam. ; reproductive cells 6-34 //, in diam.
Colonies 40-400 /* in diam.

Clam (ss), Mud (1) (cc), Sand (1) (r).

VOLVOX L. 1758.

Colonies always motile, spherical to ovoid, containing a large number
of cells arranged in a single layer just within the periphery of the
homogeneous, hyaline, gelatinous, colonial envelope. Cells differen-
tiated into those for vegetative purposes, asexual, and sexual repro-
duction. Vegetative cells close together or some distance from one
another, with or without cytoplasmic connections of varying thickness.
Cell shape spherical, ovoid, or disciform. Individual cells or groups
of cells sometimes enclosed by their own gelatinous envelope. Cells
with two cilia of equal length, 2-6 contractile vacuoles, one nuclei

98 WISCONSIN PHJTOPLANKTON

one eyespot, and a cup-shaped to disciform chloroplast that contains
one pyrenoid. Number of cells in a colony varying from 200-22,000.

Asexual reproductive cells few in number (rarely more than 20) and
forming autocolonies by repeated division, the young colonies migrat-
ing to the center of the coenobe at a certain stage in their development.

Sexual reproduction heterogamous, monoecious or dioecious, with a
development of 6-400 cells into spherical oospheres and few or many
of the cells into antheridia that contain 16-256 biciliate fusiform anther-
ozoids. Zygote with a smooth or stellate wall.

KEY TO THE SPECIES.

Cells with cytoplasmic connections.

Cytoplasmic connections heavy ,- V. GLOBATOR

Cytoplasmic connections delicate V. ATTREUS

Cells without cytoplasmic connections V. MONONAE

VOLVOX GLOBATOR L. PI. 18, Figs. 3-5.

Systema natura, Ed. 10: 820. 1758; Cohn, Beitr. z. Biol. d. Pflanzen 1, Heft 3:
93, pi. 2, figs. 1-6. 1875.

Colonies large, with many (1,000-22,000) cells that are flattened and
pentagonal to octagonal in surface view. Cells connected to one an-
other by stout cytoplasmic strands. Chloroplast of cells single, flat-
tened and angular, with one pyrenoid. Cells with 2-6 contractile vacu-
oles at the base of the two cilia and with an eyespot. Gelatinous sheaths
of individual cells sharply defined and (in surface view) pentagonal
to octagonal by mutual compression. Generally with 8 asexual repro-
ductive cells giving rise to autocolonies. Colonies commonly monoe-
cious, with 12-40 (generally 20-30) oospheres enclosed by large gelat-
inous vesicles. Antherids a flat plate of 64-256 fusiform antherozoids
with laterally attached cilia. Zygote verrucose, with conical warts.
( Tychoplanktont) .

Cells 2-7.5 (generally 3-5) ^ in diam. Colonies 400-800 //, in diam.

Center (s), Hooker (rr), Kegonsa (rr), Monona (r), Soft (rrr), Waubesa
(rrr).

VOLVOX AUREUS Ehrenberg. PI. 18, Fig. 2.

Die Infusionsthierchen 71, pi. 4, fig. 2. 1838; Klein, Jarhb. f. wiss. Bot. 20:
138, pi. 12, figs. 26-33. 1889.

Colonies spherical, containing a comparatively small (200^,000)
number of cells. Cells circular in surface view, connected with one
another by very fine cytoplasmic strands. Individual gelatinous sheaths
of cells confluent with the colonial envelope. Cells containing a spheri-

WISCONSIN PHYTOPLANETON 99

eal chloroplast, one eyespot, and a pair of contractile vacuoles at the
base of the two cilia. 4-14 asexual reproductive cells giving rise to
autocolonies. Colonies generally dioecious, with 3-9 oospheres and
about half of the cells developing into antherids that contain 16-32
fusiform antherozoids with two terminal cilia. Zygote smooth-walled.
(Facultative Planktont).
Cells 5-9 /A in diam. ; colonies 200-680 /*, in diam.

Beaverdam (rrr), Camp (sss), Center (ss), Delavan (ss), Eagle (rr), Eliza-
beth (rrr), Fowler (rrr), Jennie (rrr), Kawaguesaga (rrr), Lac du Flam-
beau (rr), Lac la Belle (rr), Mill (rrr), Oconomowoc (rrr), Paddock (r),
Pokegama (1) (rr), St. Croix (rrr), Silver (2) (rr).

Volvox mononae sp. nov. PI. 18, Fig. 1.

Colonies spherical, containing a comparatively small (400-2500)
number of cells. Cells spherical, not connected with one another by
cytoplasmic processes. Individual sheaths of cells confluent with colon-
ial envelope. Cells containing a single bell-shaped chloroplast with
one pyrenoid, an eye spot, and two cilia whose length is 2-3 times the
diameter of the cell. 3-10 asexual colonies formed inside the coeno-
bium and these daughter colonies in turn frequently containing young
colonies. Asexual reproductive cells becoming much larger than vege-
tative cells before division commences. Colonies dioecious, with oogonia
and antheridia in young daughter colonies only. 20-60 cells of a
young colony formng typical Volvox antheridia that generally contain
64 antherozoids. Female colonies with 6-10 oospheres. Zygote smooth
walled.

Vegetative cells 5-8 /x in diam. Colonies 50-350 //, in diam.

Monona (aaa).

Order PROTOCOCCALES.

Vegetative cells immobile ; free-floating, sessile, or epiphytic ; solitary
or in colonies. Colonies amorphous and frequently embedded in a
gelatinous envelope; or of definite shape and with or without a gelati-
envelope. Colonies capable or incapable of increasing the number of
their cells after they are formed. Cells variously shaped, generally
with one chloroplast and pyrenoid.

Asexual reproduction by zoospores, fragmentation of the colony, auto-
spores, or autocolonies. Resting akinetes known in some species.

Sexual reproduction by isogamous zoogametes known but not found
in a majority of the genera.

100 WISCONSIN PHYTOPLANKTON

KEY TO THE FAMILIES.

Asexual reproduction by zoospores.

Cells epiphytic or endophytic PLANOSPOBACEAE

Cells or colonies free-floating.

Colonies capable of growth by cell division PALMF.T.T.ACEAS

Colonies incapable of growth by cell division HYDBODICTYACEAE

Asexual reproduction by autospores or division of cells.
Cells capable of vegetative division.

Solitary, in regular masses, or in strata PBOTOCOCCACEAE

In colonies held together by remains of old cell walls. . DICTYOSPH AKRIACEAE
Cells incapable of division except to form autospores AUTOSPORACEAE

Family PALMELLACEAE.

Cells spherical, ovoid, or reniform; rarely solitary, generally united
to form, colonies which, are at times of macroscopic size. Colonies al-
ways embedded in a gelatinous matrix. Colonies capable of an in-
crease in size by the vegetative division of the constituent cells. Chloro-
plasts generally single, cup-to disc-shaped and parietal ; or star-shaped
and central ; with or without pyrenoids.

Reproduction by the fragmentation of the colony or by zoospores.

Sexual reproduction known in certain genera.

KEY TO THE GENERA.

Chloroplast star-shaped and central ASTEEOCOCCTJS

Chloroplast cup- to disc-shaped and parietal.

. Cells with pseudocilia TETBASPOBA

Cells without pseudocilia.

Gelatinous envelope of colony lamellated GLOEOCYSTIS

Gelatinous envelope of colony homogeneous.
Cells spherical.

Chloroplast of old cells cup-shaped SPHAEROCYSTIS

Chloroplast of old cells disciform PLANKTOSPHAEBIA

Cells ovoid to reniform GLOEOCYSTOPSIS

GLOEOCYSTIS Nageli 1849.

Cells spherical; solitary or in small colonies of eight cells or less.
Each cell and the whole colony surrounded by a hyaline, lamellated,
gelatinous sheath. Chloroplast of young cells cup-shaped, parietal, and
with one pyrenoid ; generally diffuse and rich in starch in old cells.

Asexual reproduction by a fragmentation of the colony through the
softening of the gelatinous envelope, or by zoospores. Akinetes known.

WISCONSIN PE7TOPLANETON 101

GLOEOCYSTIS GIGAS (Kiitzing) Lagerheim. PI. 19, Fig. 2.

ofvers. kgl. Vet.-Ak. Forh. 40: No. 2: 63. 1883; G. S. West, Brit. Freshw.
Algae 245: figs. 113F-113H. 1904.

Cells spherical; solitary or in families of 2-8; enclosed by a thick,
distinctly lamellated, gelatinous envelope. Chloroplast of young cells
cup-shaped, of older cells diffuse. (Tychoplanktont).

Cells 9-17 p in diam. ; colonies 45-95 p. in diam.

Mendota (IT), Oconomowoc (rr).

SPHAEROCYSTIS Chodat 1897.

Colonies spherical with the cells in groups of 4-8-16-32 and disposed
towards the periphery of a hyaline, homogeneous, gelatinous envelope
and with the envelope surrounding each group of cells distinct or con-
fluent with the colonial envelope. Colonies sometimes forming palmella
stages where the cells are irregularly disposed. Cells spherical ; chloro-
plast cup-shaped or filling the entire cell, with one pyrenoid.

Reproduction by the liberation of a group of cells through the soften-
ing of the colonial envelope. Zoospores of two sizes have been observed.

SPHAEROCYSTIS SCHROETERI Chodat. PI. 19, Figs. 3-4.

Bull. Herb. Boiss. 5: 119, pi. 9, figs. 1-12. 1897; G. S. West, Jour. Linn. Soc.
Bot. 39: 76, figs. 9A-9F. 1909.

Characters the same as those of the genus. ( Euplanktont) .
Diam. cells 6-22 /* ; diam. colonies 50-500 /*.

Balsam (rr), Bear (2) (ss), Bear Trap (sss), Beasley (rr), Big (sss), Big
Butternut (rr), Birch (1) (rr), Birch (2) (ss), Birch Island (rr), Boulder
(ss), Browns (rr), Camp (rr), Carson (rr), Catfish (rr), Center (rr), Chetac
(ss), Chetek (cc), Clam (rrr), Clear Crooked (s), Crab (r), Cranberry (rr),
Deer (rr), Devils (1) (sss), Eagle (rr), East (rr), Elizabeth (sss), Found (r)
Fowler (rr), Green (1) (rr), Half Moon (rr), Hillman (rr), Hooker (rr),
Kimball (rr), Kitten (rr), Lac Court Oreilles (rr), Lac du Flambeau (r),
Lac la Belle (ss), Little Bass (1) (ss), Little Butternut (r), Little Doctor
(rr), Little Wood (rr), Long (1) (ss), Long (2) (rr), Long (3) (rrr), Love-
less (rr), Lower Nashotah (rr), Lower Nemahbin (cc), Lower Turtle (r),
Mary (ss), Mendota (r), Meta (ccc), Mill (sss), Monona (r), Mud (1) (rr),
Mudhen (sss), Nicaboyne (r), No Mans (rr), North Turtle (rr), North Twin
(rr), Number One (cc), Oconomowoc (ss), Okauchee (ss), Old Taylors (rr),
Pike (rr), Pine (2) (rr), Pine Tree (rr), Pokegama (1) (ss), Pokegama (3)
(sss), Poplar (ss), Prairie (ss), Rainbow (rr), Rice (1) (ss), Rock (r),
Round (1) (rrr), Round (2) (rr), Rudolph (rr), Sand (3) (rr), Sand (4)
(rrr), Shell (ccc), Silver (2) (r), South Turtle (r), Tamarack (rr), Upper
Nemahbin (rr), Upper Turtle (rr), Waubesa (rr), Winnebago (r).

102 WISCONSIN PHYTOPLANKTON

Lemmermann follows Wille in placing the alga as a synonym of
Braun's old genus Gloeococcus but I prefer to follow G. S. West's
practice and consider the two genera distinct. The ordinary vegetative
condition is easily recognized but the rather rare palmella stage may be
mistaken for one of the limnetic Tetraspora species.

TETRASPORA Link 1809.

Colonies macroscopic or microscopic ; attached or free-floating ; gelat-
inous ; spherical, cylindrical, expanded, or variously lobed. Cells spher-
ical, generally in groups of four towards the periphery of the homo-
geneous, hyaline, gelatinous colonial envelope. Sometimes irregularly
distributed within the gelatinous colonial envelope. Chloroplast cup-
shaped, parietal ; sometimes diffuse ; with one pyrenoid. Each cell with
two or four long, hyaline, gelatinous bristles (pseudocilia).

Asexual reproduction by the direct metamorphosis of vegetative cells
into biciliate zoospores.

Sexual reproduction by a division of vegetative cells to form 4r-8
bilciliate zoogametes that fuse in pairs.

TETRASPORA LACUSTRIS Lemmermann. PL 19, Figs. 5-6.

Bot. Cent. 76: 152. 1898; Forschungsbr. a. d. Biol. Stat. zu Plon 7: 118, pi. I,
fig. 13. 189'9.

Colonies microscopic; spherical, elongate, or irregular in shape; al-
ways free-floating. Cells spherical, generally in groups of four and
with pseudocilia 6-8 times as long as the diameter of the cell. Chloro-
plast single, cup-shaped, and parietal ; with or without pyrenoids. (Eu-
planktont).

Diam. cells 7-10 p.; diam. colonies up to 300 p..

Crawling Stone (sss), Fence (rrr), Long (3) (sss), Mud (2) (sss), Pike
(rrr).

Small colonies frequently resemble palmella stages of Spliaerocystis
Schroeteri but Tetraspora may be recognized by the pseudocilia. In
case of doubt it is always advisable to stain with safranin to bring out
the pseudocilia.

GLOEOCYSTOPSIS G. M. Smith 1916.

Cells elongate-cylindrical, with rounded ends and more or less curved.
Cells aggregated in fours or eights within a homogeneous gelatinous
sheath. Colonies spherical to ovoid and composed of an indefinite num-
ber of these aggregates. Colony not enclosed by a gelatinous sheath.

WISCONSIN PHYTOPLANKTON 103

Chloroplast of young cells single, laminate, parietal, with one pyrenoid ;
diffuse in old cells.
Reproduction, aside from vegetative cell division, unknown.

GLOEOCYSTOPSIS LIMNETICUS G-. M. Smith. PI. 20, Figs. 1-2.
Bull. Torr. Bot. Cl. 43: 475, pi. 24, fig. 12. 1916.

Cells 4r-6 fL broad, 10-15 /* long. Cell aggregates 25-30 /t in diam. ;
colonies up to 125 /A in diam. (Euplanktont).

Bear Trap (rr), Beaverdam (rrr), Catfish (IT), Harris (rrr), Little Bass
(2) (rrr).

A species that combines the general external morphological character-
istics of Gloeocystis and the cell shape of N ephrocytium.

PLANKTOSPHAERIA G. M. Smith 1918.

Cells spherical, embedded in a copious, homogeneous, hyaline, gelat-
inous envelope. At first solitary, later irregularly distributed within
the gelatinous envelope. Mature cells with several parietal, polygonal,
flattened chloroplasts each of which contains a single pyrenoid.

Reproduction by liberation of daughter colonies through the breaking
down of the gelatinous colonial envelope.

PLANKTOSPHAERIA GELATINOSA G. M. Smith. PI. 20, Figs. 3-6.
Trans. Wis. Acad. Sci., Arts, & Lett. 19l: 627, pi. 10, figs. 8-11. 1918.

Specific characters as described above. (Euplanktont).
Diam. cells 4.5-25 p ; colonies up to 150 p. in diam.
Browns (rr), Mendota (r).

The general appearance of the colony suggests Spha&rocystis
Schroeteri but P. gelatinosa differs in the numerous parietal chloroplasts
of each cell.

ASTEROCOCCUS Scherffel 1908.

Cells spherical or sub-spherical, solitary or in colonies, with a wide,
homogeneous or lamellated, gelatinous envelope. Chloroplast single,
central, star-shaped, the astral radiations ending in a disc at the cell
wall. Pyrenoid single, at the center of the chloroplast. Certain species
with two peripheral vacuoles and an eyespot.

Asexual reproduction by vegetative cell division and biciliate sub-
spherical zoospores.

Sexual reproduction unknown.

104 WISCONSIN PHYTOPLANETON

ASTEBOCOCCUS LJMNETicus G. M. Smith. PI. 20, Figs. 7-10.
Trans. Wis. Acad. Sci., Arts, & Lett. 191: 627, pi. 10, figs. 3-6. 1918.

Colonies spherical, rarely ovoid, of 4-8-16 spherical cells widely
separated from one another and lying within a hyaline, homogeneous,
gelatinous matrix. Chloroplast single, star-shaped, with 4 or 8 (rarely
16) rays coming from a central mass and ending in a disc at the cell
wall. Pyrenoid single, at the center of the chloroplast. (Euplanktont).

Diam. cells 7.5-35 /A; colonies up to 125 /* in diam.

Chain (r),Clam (sss), Crooked (rrr), Deer (rrr), Des Moines (IT), Dummy
(ss), Fish (sss), Half Moon (rr), Hillman (rrr), Horseshoe (1) (ss), Horse-
shoe (2) (rr), Howey (rr), Lac Court Oreilles (ss), Lake of the Woods (rr),
Long (1) (r), Nancy (r), North Twin (rrr), Owen (cc), Reserve (r), Rooney
(rr), Sand (1) (r), Sand (3) (r), Shell (cc), Whitefish (sss), Wild Goose
(rrr).

The shape and cellular arrangement in colonies of this species is
quite similar to that of Sphaerocystis, but a sharp distinction exists in
its star-shaped chloroplast, a type of chloroplast that is very uncommon.
The alga is widely distributed in the lakes of northwestern Wisconsin.

Family DICTJOSPHAERIACEAE.

Cells in spherical or ovoid colonies, the number in young colonies a
multiple of two, in older colonies indefinite. Colonies with or without
a gelatinous envelope. Cells held together in fours or eights by the
persistence of the old mother cell wall in repeatedly branching four-
armed thongs or irregular threads. Chloroplast single; cup-shaped,
or filling the entire cell ; with one pyrenoid.

Reproduction by the division of cells into autospores which remain
attached to mother colony until accidentally broken away.

KEY TO THE GENERA.

Colony enclosed in a gelatinous sheath DICTYOSPHAERITTM

Colony not enclosed in a gelatinous sheath.

Cells spherical WESTELLA

Cells ovoid to renif orm DIMOBPHOCOCCTJS

DICTYOSPHAERIUM Nageli 1849.

Cells spherical, ovoid, or reniform, connected with one another by
cruciately or dichotomously branching threads. Colony enclosed by a
hyaline, homogeneous, gelatinous envelope that is spherical or ovoid in
shape. Chloroplast single, parietal, cup-shaped, with one pyrenoid.

WISCONSIN PHJTOPLANKTON 105

^Reproduction by the division of the cell into 2 or 4 daughter cells
which remain connected to the colony by the old mother cell wall that
divides into 2 or 4 parts to form the branching thread system connect-
ing the cells. Zoospores reported but their existence is very doubtful.
Kesting akinetes known.

KEY TO THE SPECIES.

Mature cells ovoid D. EHRENBERGIANUM

Mature cells spherical D. PTOOHELLTIM

DlCTYOSPHAERIUM EHRENBERGIANUM Nageli. PI. 20, FigS. 11-12.
Gatt. einz. Algen, 73, pi. 2, figs. Ea-E1. 1849.

Colonies spherical to ovoid, rarely containing more than 30 cells.
Cells ovoid to ellipsoid when mature. Chloroplasts 1-2, parietal, lami-
nate, generally with a single pyrenoid. (Facultative Planktont).

Cells- 4-7 n broad ; 6-10 /t long.

Clear (rr), Kegonsa (rrr>. Mendota (rr).

DICTYOSPHAERIUM PULCHELLUM Wood. PI. 20, Fig. 13 ; PI. 21, Fig. 1.
Smithsonian cont. to knowl. 19, No. 241: 84, pi. 10, fig. 4. 1872.

Colonies spherical to broadly ovoid, of 4-8-16-32 or many cells lying
near the periphery of the hyaline, homogeneous, gelatinous envelope.
Cells spherical when mature, spherical to ovoid when young ; generally
in fours at the ends of a repeatedly branching system of threads. Chloro-
plast single, parietal, cup-shaped, with one pyrenoid. (Facultative
planktont).

Diam. cells 3-10 /*.

Amicoy (ss), Balsam (rrr), Bear (1) (ss), Bear (2) (r), Bettine (s), Big
Butternut (r), Birch (1) (r), Birch (2) (rrr), Blake (ss), Bone (r), Boulder
(rrr), Canteen (rr), Carson (sss), Catfish (r), Catherine (rrr), Center (r),
Chain (rr), Chetac (ss), Chetek (ss), Crab (s), Cranberry (rr), Crawling
Stone (rrr), Deer (rr), Diamond (rr), Duck (cc), Dummy (sss), Eagle (rr),
Elizabeth (rrr), Fishtrap (rr), Granite (ss), Grassy (rr), Grindstone (rr),
Half Moon (rr), High (rr), Hillman (ss), Horse (rr), Horseshoe (1) (rrr),
Horseshoe (2) (ss), Howey (rr), Jag (rr), Kawaguesaga (rr), Kegonsa (r),
Kitten (rrr), Lac Court Oreilles (ss), Lac du Flambeau (rr), Lindy (rr),
Little Bass (1) (rr), Little Bass (2) (rr), Little Butternut (rr), Little Crooked
(rrr), Little Rice (2) (sss), Little Wood (sss), Long (1) (rrr), Long (3)
(rrr), Loon (r), Loveless (rr), Lower Turtle (r), Lynx (rrr), Mendota (ss),
Mercer (rrr), Middle McKenzie (rrr), Monona (ss), Mud (2) (rr), Mudhen
(rr), Nagawicka (rrr), Nancy (r), Nicaboyne (rr), North Turtle (r), Ocono-
mowoc (r), Okauchee (rr), Old Taylors (rr), Owen (rrr), Palmer (rr), Pe-
waukee (rr), Pine Tree (sss), Pokegama (1) (r), Pokegama (3) (c), Poor

106 WISCONSIN PHTTOPLANKTON

Farm (rrr), Prairie (c), Reserve (rr), Rice (ss), Rock (rr), Rooney (rr),
Rose (sss), Rozen (rr), St. Croix (rrr), Sand (3) (rrr), Shell (cc), Sishe-
bogema (rr), .South Turtle (rr), Spirit (r), Tamarack (sss), Tenderfoot (rr),
Tied Canoe (rrr), Travis (rr), Upper Nashotah (sss), Upper Nemahbin (rr),
Vermilion (r), Wapagossett (rrr), Waubesa (ss), White Ash (sss), Whitefish
(rr), White Sand (rr), Wild Goose (s), Winnebago (sss).

DIMORPHOCOCCUS A. Braun 1855.

Cells in groups of four and held in an irregular free-floating colony
by the branching remains of the old mother cell wall. Colony not en-
closed by a gelatinous envelope. Each aggregate of four cells lying in
one plane with two cells ovoid to cylindrical with rounded ends, and two
cells reniform to cardioid. Chloroplast of young cells single, parietal,
laminate, with one pyrenoid; chloroplast of old cells occupying the
entire cell.

Reproduction by the division of any cell into four daughter cells
which remain attached to the colony by the threadlike remains of old
cell wall until accidentally broken away.

DIMORPHOCOCCUS LUNATUS A. Braun. PI. 21, Fig. 5.

Alg. Unicell. 44. 1855; Rabenhorst, Fl. Eur. Algarum 3: 36, figs, a-c (p. 6).
1868; G. S. West, Brit. Freshw. Algae 221, figs. 93A-93s. 1904.

Cells of each group of four alternately arranged (in vertical view)
the central cells cylindrical with rounded ends, the terminal cells reni-
form to cardioid. (Facultative planktont).

Cells 4-15 fji. broad, 9-25 /t long. Colonies up to 150 /* in diam.

Bear (2) (rr), Bear (3) (rr), Beaver dam (rrr), Blue Gill (rrr), Catfish
(rr), Des Moines (rrr), Devils (2) (rr), Horseshoe (1) (rr), Horseshoe (2)
(rrr), Kegonsa (rrr), Lindy (rr), Minocqua (rrr), Mud (1) (rr), Pike (rr),
Pine (1) (rr), Pine Tree (rrr), St. Croix (rrr), Shell (rrr).

WESTELLA de Wildeman 1897.

Cells small, spherical to sub-spherical, grouped in fours (rarely
eights) in irregular, free-floating colonies containing 30-100 cells; the
colony being held together by the non-gelatinizing remains of the old
mother cell walls. Colonies without a gelatinous envelope. Chloro-
plast cup-shaped and parietal, or entirely filling the cell, with or with-
out a pyrenoid.

Reproduction by the division of any cell to form 4-8 autospores that
remain connected with the mother colony until accidentally broken
away.

WISCONSIN PHYTOPLANKTON 107

KEY TO THE SPECIES.

Groups with cells quadrate or pyramidate W. BOTRYOIDES

Groups with cells in a linear series W. LINEABIS

WESTELLA BOTRYOIDES (W. West) de Wildeman. PI. 21, Fig. 4.

Bull. Herb. Boiss. 5: 532. 1897.

Tetracoccus botryoides W. West, Jour. Roy. Micr. Soc. 1892: 735, pi. 10,
figs. 43-48. 1892.

Colonies irregularly shaped, without a gelatinous envelope, generally
containing 40-80 cells. Cells spherical, pyramidately or quadrately
arranged in groups of four (rarely eight). Chloroplast single, cup-
shaped or entirely filling the cell; with or without a pyrenoid. (Facul-
tative Planktont).

Diam. cells 3-9 /*,.

Blake (rrr), Fishtrap (rr), Hillman (rrr), Horse (rrr), Horseshoe (1) (rr),

Jag (r), Little Bass (2) (rr), Little Butternut (rrr), Little Crooked (rr),

Mendota (rrr), Mill (rrr), Nancy (rr), Pine Tree (rr), Round (3) (rr),
Sishebogema (rr).

var. MAJOR Gr. M. Smith.
Trans. Wis. Acad. Sci., Arts, & Lett. 191: 628. 1918.

Cells larger than the typical form, otherwise the same.
Diam. cells 8-13 p.

Whitefish (rr).

Westella linearis sp. nov. PI. 21, Figs. 2-3.

Colonies of irregular shape, rarely containing more than 40 cells.
Cells spherical, always in groups of four and arranged in a linear
series. Remains of old mother cell walls that hold the colony together
very inconspicuous. Colony without a gelatinous envelope. Chloro-
plast single, parietal, without a pyrenoid. (Euplanktont ?).

Diam. cells 3-6 //,.

Pine Tree (rr).

In the arrangement of the cells this species is quite unlike the other
members of the genus but since the cells are in groups of four that are
held together by the remains of old mother cell walls it seems better
to place it in this genus than in Crucigenia.

108 WISCONSIN PETTOPLANETON

Family PROTOCOCCACEAE.

Cells solitary and spherical; or in colonies containing an indefinite
number of cells that are spherical and mutually compressed or in very
short irregular filaments. Cell wall delicate to heavy, smooth or vari-
ously sculptured. Chloroplast single, parietal and disciform, with or
without pyrenoids. Cells capable of vegetative division.

Reproduction, aside from vegetative division of cells, by zoospores or
aplanospores.

KEY JO THE GENERA.

Cell wall thin, smooth CHLOBELLA

Cell wall thick, sculptured TBOCHISCIA

CHLORELLA Beyerinck 1890.

Cells small, spherical ; solitary or in small colonies of indefinite shape.
Chloroplast disciform to cup-shaped, with or without a pyrenoid.

Reproduction by the division of cell contents into 2-4-8 daughter
cells. Resting akinetes known.

CHLORELLA VULGARIS Beyerinck. PI. 22, Fig. 1.

Bot Ztg. 48: 758, pi. 7, figs. 2^-2\ 18&0.

Cells spherical, generally solitary. Chloroplast parietal, cup-shaped,
with or without a pyrenoid. Cell wall smooth and delicate. (Faculta-
tive Planktont).

Diam. cells 5-10 /u,

Mendota (rr).

C. vulgaris is a minute alga and one that is easily overlooked. The
record of its occurrence in Lake Mendota is based upon its isolation by
pure culture methods from a plankton catch. It is very probable that
it is present in other lakes but has been overlooked.

i

TROCHISCIA. Kiitznig 1845.

Cells spherical to sub-spherical, solitary or in small clumps. Cell
wall fairly heavy, areolate or ornamented with spines, denticulations,
ridges, or other projections. Cells generally containing several parietal
disciform chloroplasts each with a pyrenoid.

Reproduction by vegetative cell division or the formation of 4-16
aplanospores that are liberated by the dissolution of the old mother
cell wall.

WISCONSIN PHTTOPLANKTON 1Q9

TROCHISCIA RETICULARIS (Reinsch) Hansgirg. PI. 22, Fig. 2.

Hedwigia 27: 129. 1888.

Acanthococcus reticularis Reinsch, Ber. d. D. bot. Ges. 4: 242, pi. 12, figs.
1886.

Cells generally solitary, spherical. Cell wall fairly thick and covered
with linear ridges that intersect to form 50-70 polygons on the surface
of the cell. (Tychoplanktont).

Diam. cells 24-32 /*.

Wildcat (rrr).

Family AUTOSPORACEAE.

Cells solitary or in colonies that are generally of a definite shape and
without a gelatinous envelope. Cells variously shaped; with a single
chloroplast and pyrenoid as a rule. Cells incapable of vegetative divi-
sion to form two similar daughter cells.

Reproduction by division of cell contents into 2^-8-16-32-64 cells
which assume the shape of the mother cell before their liberation (auto-
spores). In the colonial species the autospores from any one cell are
organized to form the new colony (autocolony) before their liberation.
Motile asexual reproductive bodies or sexual reproduction unknown.

KEY TO THE SUBFAMILIES.

Cells solitary.

Cells angular TETRAEDREAE

Cells not angular.

Ornamented with long spines or setae MICRACTINIEAE (p. p.)

Not ornamented with spines or setae.

Length of cells several times the diameter SELENASTREAE (p. p.)

Length of cells not more than twice the diameter OOCTSTEAE (p.p.)

Cells in colonies.

Ornamented with long setae or spines.

Coenobe capable of growth in three directions MICRACTINIEAE (p.p.)

Coenobe a flat plate CRUCIGENIEAE (p. p.)

Not ornamented with setae or spines.
Number of cells in coenobe always a multiple of two.

Coenobe flat CRUCIGENIEAE (p. p.)

Coenobe spherical or cells radiating from a common

center i COELASTREAE

Number of cells not a multiple of two in every case.

Cells elongate, straight or curved SELENASTREAE (p. p.)

Cells spherical, ovoid, or reniform OOCYSTEAE (p. p.)

HO WISCONSIN PHYTOPLANKTON

Subfamily OOCYSTEAE.

Cells spherical, ovoid, or renif orm ; solitary or in temporary colonies.
Daughter cells retained within old mother cell wall for some time after
their formation. Walls generally thick and cells with one to many
ehloroplasts.

KEY TO THE GENERA.

Cells within old mother cell wall separated by a dark gelatinous

mass GLOEOTAENIUM

Cells within old mother ceil wall not separated by a dark gelat-
inous mass.

Cells ovoid to elliptic, never curved OOCYSTIS

Cells ovoid to renif orm, frequently curved NEPHBOCTTITJM

OOCYSTIS Nageli 1845.

Cells ovoid, ellipsoid, or cylindrical with rounded to somewhat pointed
ends, generally symmetrical but never curved. Cell wall smooth, with-
out spines, frequently with nodular thickenings at the poles. Chloro-
plasts one to many; parietal, disciform, stellate, or reticulate; with or
without pyrenoids. Cells solitary or in temporary colonies of 2-4-8-16
or more enclosed by the partially gelatinized and greatly swollen old
mother cell wall.

Eeproduction by a formation of 2-4-8-16 autospores that remain
within the old cell wall for some time. Three to four cell generations
sometimes enclosed by the same wall. Tetraedron-like resting spores
with granulate walls have been observed.

The genus differs from others in the expanded cell wall that encloses
the cells in temporary colonies. Printz (Nyt. Mag. f. Naturvidensk.
1913, p. 165) has recently monographed the genus and cleared up many
points by collecting the published descriptions of species; but there is
great need of a series of cultural studies to determine the range of
variation within the so-called "species" that are recognized at the
present time.

KEY TO THE SPECIES.

Chloroplast stellate O. NATANS

Chloroplast disciform to laminate.
Cells with polar nodules.

Sides of cells concave O. PANDTJRIFOKMIS

Sides of cells convex.
4 or more ehloroplasts in each cell.
Cells with 40-60 ehloroplasts 0. EBEMOSPHAERIA

WISCONSIN PHYTOPLANKTON HI

Cells with 6-25 chloroplasts.

Polar nodules conspicuous, 12-25 chloroplasts O. SOLITABIA

Polar nodules not prominent, 4-10 chloroplasts O. CBASSA

1-2 (rarely 4) chloroplasts in each cell.

Cells elliptic, length iy2 times breadth O. LACUSTRIS

Cells oblong-cylindrical, length 2-3 times breadth 0. SUBMAKINA

Cells without polar nodules.

Poles of cells rounded.

Length of cells less than 12 fj. O. PUSH-LA

Length of cells more than 12 IL.

1-4 chloroplasts in each cell O. BOBGEI

8-10 chloroplasts in each cell O. ET.UPTICA

Poles of cells pointed.

Old cell wall enclosing colonies rounded O. PABVA

Old cell wall enclosing colony sharply pointed . .0. GLOEOCYSTIFOBMIS

OOCYSTIS PUSILLA Hansgirg. PI. 22, Fig. 3.

Sitzbr. d. k. bohm. Ges. d. Wiss. in Prag, Jahrgang 1890: 9. 1890; Printz, Nyt.
Mag. f. Naturvidensk. 51: 181, pi. 4, figs. 31-32. 1913.

Cells cylindrical, poles rounded and without nodules. Chloroplasts
2-3, parietal, laminate, without pyrenoids. Temporary colonies con-
taining 2-^4-8 cells. ( Tychoplanktont) .

Diam. cells 4.5-6.5 /j. ; length 8-12 /*.

Tied Canoe (rr).

OOCYSTIS BORGEI Snow. PI. 22, Fig. 4.
Bull. U. S. Fish Comm. 22: 379, pi. 2, figs. VIP-VII6. 1903.

Cells broadly elliptic, length l^ times the breadth; poles rounded
but without nodules. Chloroplasts 1-4, parietal, laminate, each con-
taining a single pyrenoid. Cells solitary or in families of 2-4-8 within
an old mother cell wall. (Euplanktont).

Cells 9-13 p. broad, 9-17 /* long.

Big (rr), Birch (1) (sss), Camp (r), Catfish (r), Devils (1) (rr), Duck
(r), Found (rr), Green (2) (rr), Kawaguesaga (rr), Kitten (rrr), Long (2)
irr), Mendota (r), North Turtle (r), Pardee (rr), Rock (r), Winnebago (rr).

OOCYSTIS ELLIPTICA W. West. PI. 22, Fig. 5.
Jour. Roy. Micr. Soc. 1892: 736, pi. 10, fig. 56. 1892.

Cells oblong-elliptic, with poles rounded and without nodules. Chlor-
oplasts 10-20, disciform, parietal, without (?) pyrenoids. Cells rarely
solitary, generally in families of 4—8 within an old mother cell wall.
( Tychoplanktont) .

Cells 11-12.5 /x broad, 20-25 /* long.

Amicoy (rr).

112 WISCONSIN PHYTOPLANKTON

OOCYSTIS PARVA W. & G. S. West PI. 22, Fig. 6.

Jour, of Bot. 36: 335. 1898; G. S. West, ibid. 37: 223, pi. 394, figs. 14-17. 1899.

Cells broadly fusiform to elliptic, ends pointed but without polar
nodules. Each cell with 1-3 parietal, laminate to disciform chloro-
plasts, with or without pyrenoids. Cells solitary or in families of 2-4-8.
(Facultative Planktont).

Cells 4-7 //, broad ; 6-12 p. long.

Beaver (1) (rr), Bettine (rr), Clear Crooked (rr), Cochrane (rrr), Crab
(rrr), Deer (rr), George (rr), Half Moon (rr), Hooker (rr), Little Bass (2)
(rr), Lynx (rr), Mendota (rr), Muskallonge (rr), Palmer (rr), Pine (1) (rr),
Rudolph (rr), Sand (1) (rrr), Stone (rr), Wolf (rr).

OOCYSTIS GLOEOCYSTIFORMIS Borge. PI. 22, Fig. 7.
Botaniska Studier till. F. R. Kjellman 23, pi. 1, figs, la-lb. 1306.

Cells narrowly elliptic with ends pointed. Chloroplast single, pari-
etal, without a pyrenoid. Cells in families of 2-4 within the old cell
wall, several cell generations frequently forming a single colony. Wall
enclosing colony with pointed ends but no polar nodules. (Tychoplank-
tont).

Breadth of cell 3-5.5 p. ; length 8-15 /*..

Lac Court Oreilles (sss).

The old mother cell wall does not gelatinize as readily in this species
as in others so that several cell generations are generally found in the
same colony. The species is best recognized, however, by the sharply
pointed ends of the colony wall.

OOCYSTIS LACUSTRIS Chodat. PL 22, Figs. 8-9.
Bull. Herb. Boiss. 5: 119, pi. 10, figs. 1-7. 1897.

Cells elliptic to broadly fusiform, somewhat pointed and with a
nodule at the poles. Chloroplasts 1-3, laminate, parietal, with or with-
out pyrenoids. Margins of chloroplasts sometimes irregular. Cells
rarely solitary, generally in families of 2-4-8 within the old mother
cell wall. (Euplanktont).

Cells 8-22 /* broad, 14-32 p. long.

Big Butternut (rr), Bone (rr), Center (r), Chain (rr), Chetek (r), Devils
(2) (ss), Dummy (rr), Fowler (rr), Hillman (rr), Little Bass (2) (rr),
Little Butternut (rrr), Long (2) (rrr), Long (3) (rrr), Mary (r), Mercer
(rr), Palmer (rr), Pokegama (3) (rr), Prairie (rr), Reserve (rr), Sand (4)
(rr), Sishebogema (rrr), Upper Nashotah (rrr), Upper Turtle (sss), White
Sand (rr).

WISCONSIN PHYTOPLANKTON 113

OOCYSTIS SUBMARINA Lagerheim. PI. 22, Fig. 10.
Bot. Not 1886: 45, fig. 1. 1886.

Cells oblong-cylindrical, 2-3 times as long as broad, somewhat pointed
and with a nodule at each pole. Chloroplasts 1-2, laminate, parietal,
usually with a pyrenoid. Cells rarely solitary, generally in families
of 2-4-8-16 within the old mother cell wall. (Tychoplanktont).

Cells 3-9 fji broad, 7-20 /* long.

Camp (sss), Upper Nemahbin (rr).

OOCYSTIS SOLITARIA Wittrock. PI. 22, Fig. 11.
Bot. Not. 1879: 24, figs. 1-5. 1879.

Cells ovoid to ellipsoid, solitary or in families of 2-4-8. Cell wall
fairly thick and with conspicuous polar nodules. Chloroplasts numer-
ous (generally 12-25), parietal, discifonn to polygonal, with or with-
out pyrenoids. (Facultative Planktont).

Cells 7-20 ^ broad, 14-35 p. long.

Hooker (r), Sand (1) (rr).

OOCYSTIS CRASSA Wittrock PI. 22, Figs. 12-13.

Bot. Not. 188O: 117. 1880.

Cells ovoid, length l1/^ times the breadth, with a nodule at each pole.
Chloroplasts 4-10 in number, fairly large, parietal, disciform to angu-
lar, generally with a pyrenoid. Cells solitary or in families of 2-4-8.
Old cell wall enclosing the colony greatly distended. (Tychoplanktont) .

Cells 10-20 /* broad, 14-26 /t long.

St. Croix (rr).

OOCYSTIS EREMOSPHAERIA G. M. Smith. PI. 23, Figs. 1-2.
Trang. Wis. Acad. Sci., Arts, & Lett. 191: 630, pi. 14, figs. 8-9. 1918.

Cells ovoid, 1% to 2 times as long as broad. Solitary or in families
of 2-4. Chloroplasts numerous (40-60), parietal, lenticular, each con-
taining a single pyrenoid. Cell wall thick, with a conspicuous polar
nodule. (Facultative Planktont ?).

Cells 23-31 ft broad, 35-45 //. long.

Beaver dam (rr), Shell (sss).
8

WISCONSIN PHTTOPLANETON

OOCYSTIS PANDURIFORMIS var. MINOR G. M. Smith. PI. 23, Fig. 3.
Bull. Torr. Bot. Cl. 43: 471, pi. 24, fig. 2. 1916.

Cells oblong-ovoid, 2 to 2y2 times as long as broad, sides slightly
concave and poles with a conspicuous nodule. Chloroplasts numerous
(15-25), parietal, disciform, and each containing a pyrenoid. Cells
solitary or in families of 2-4-8. (Tychoplanktont).

Greatest diameter of cells 12-15 p., median diameter 11-14; length
30-35 p.

Star (rr).

This is the only species of the genus where the sides of the cells are
concave.

Oocystis natans var. major var. nov. PI. 23, Figs. 4-5<

Cells ovoid, without a conspicuous polar nodule. Chloroplasts 4-8,
parietal, star-shaped or irregular, each chloroplast with a pyrenoid.
More than two cell generations rarely found within the same mother
cell wall. (Facultative Planktont).

Cells 16-25 /* broad, 31-38 /* long. Families up to 90x120 /*.

Birch (2) (sss), Chetac (s), Rice (1) (rr).

Lemmermann founded the genus Oocystella upon this stellate nature
of the chloroplast (Zeits. f. Fischeri u. d. Hilfsw. 11: 103. 1903) but
the genus has not been recognized and the single species is placed in
Oocystis.

NEPHROCYTIUM Nageli 1849.

Cells ovoid, reniform, or oblong-elliptic; generally in colonies of
2-4—8-16 cells within the partially gelatinized remains of the old mother
cell wall. Arrangement of cells in young colonies spiral, in old colonies
irregular. Chloroplast single and expanded at first, later fragmenting
and becoming diffuse ; pyrenoid single.

Reproduction by the formation of 2-4-8-16 autospores in each cell.

NEPHROCYTIUM AGARDHIANUM Nageli. PI. 23, Figs. 6-7.
Gatt. einz. Algen 79, pi. 3, figs. Ca-CP. 1849.

Cells reniform, generally spirally arranged in young colonies. Chlor-
oplast single, parietal, laminate, and with one pyrenoid in young cells ;
diffuse in old cells. (Tychoplanktont).

Cells 2-12 fi broad, 6-28 /t long ; colonies up to 60 p. long.

Bear (3) (rrr), Bear Trap (rrr), Camp (rr), Hillman (rr), Little Bass
(rrr), Mendota (rr), Mill (rrr).

WISCONSIN PHY TOPLAN ETON 115

GLOEOTAENIUM Hansgirg 1890.

Cells spherical, ovoid, or variously flattened; solitary or united in
colonies of 2-^4-8 cells enclosed by a non-expanded mother cell wall and
separated from one another by a dark colored gelatinous mass that lies
between the cells. Colonies rectangular, with rounded corners in front
view ; oblong with sharp corners in side view. Cell wall thick, distinctly
lamellated ; old cell wall enclosing the colony frequently with folds and
gelatinous discs opposite the cells. Chloroplast entirely filling cells;
with or without a pyrenoid.

Reproduction by autospores and aplanospores.

GLOEOTAENIUM LOITLESBERGERIANUM Hansgirg. PI. 23, Figs. 8-9.

Sitzbr. d. k. bohm. Ges. d. Wiss. in Prag, Jahrgang 1890: 10. 1890; Transeau,
Bot. Gaz. 55: 66, pi. 3, figs. 1-24. 1913.

Cells spherical to ovoid, completely filling the space inside of old
mother cell wall. (Tychoplanktont).

Diam. cells 20-30 /*; length 2-celled colonies 40-70 /* breadth 22-40 /*;
thickness 20-30 p.. 4-celled colonies 40-70 /* broad, 40-80 /* long.

Big Butternut (rrr).

Sub-family TETRAEDREAE.

Ceils always solitary, without a gelatinous envelope, flattened or
isodiametric, triangular, quadrangular, or polyangular; angles simple
or produced into spines or long hyaline setae.

KEY TO THE GENERA.

Cells simple or with fairly stout spines at angles TETRAEDRON

Cells with long hyaline setae at angles POLYEDRIOPSIS

TETRAEDRON Kiitzing 1845.

Cells solitary, free-floating, flattened or isodiametric, triangular,
quadrangular, or polyangular. Angles simple or produced into simple
or furcate spines. Cell wall smooth or verrucose. Chloroplasts one to
many, parietal, discif orm to angular ; or completely filling the cell ; with
or without pyrenoids.

Reproduction by division of cell contents into 4-8 autospores that
are liberated by the rupture of the old mother cell wall.

. '

WISCONSIN PHYTOPLANETON

KEY TO THE SPECIES.

Angles of cells never produced into processes.
Corners of cells without spines.

Cells triangular T. MUTICUM

Cells quadrangular T. MINIMUM

Corners of cells with spines.
All cell corners in the same plane.

Cells triangular T. TBIGONUM

Cells with more than three angles.

Cells with four angles T. REGULARE v. INCUS (p. p.)

Cells with five angles T. CAUDATUM

All cell corners not in the same plane.
Cells quadrangular.

Pyramidal cells T. REGULABE

Halves of cells twisted over one another.
Wall smooth.

Angles delicately tapering T. VICTORIEAE var. MAJOK

Angles strongly convex T. REGULARE var. TOBSUM (p. p.)

Wall verrucose T. VERBUCOSUM

Cells five-angled T. PENTAEDBICUM

Angles at corners produced into processes.

Processes always unbranched T. HASTATUH

Processes always branched.

Cells flattened and processes in the same plane.

General outline of cell H-shaped T. CONSTRICUM

General outline of cell not H-shaped.

Processes long, conspicuously branched T. GBACELB

Processes short, not conspicuously branched T. LOBUIATUM (p.p.)

Cells isodiametric and processes not in the same plane.

Processes short T. ENOBME

Processes long.

With 3-5 series of branchings T. LOBULATUM var. POLYFURCATUM

Never more than three series of branchings.
Diameter of cells always greater than the length

of the processes T. PLANCTONICUM

Diameter of cell always less than the length of

the processes T. LIMNETICUM

TETRAEDRON MUTICUM var. PUNCTULATUM (Iteinsch) de Toni. PI. 23,

Figs. 10-13.

Sylloge algarum 1: 600. 1889.

Polyedrium muticum var. punctulatum Reinsch, Notarisia 3: 498, pi. 4,
fig. 6. 1888.

Cells small, triangular, somewhat flattened. Sides of cells convex in
front view. Corners sharp but without spines. Cell wall covered with
small granules. (Tychoplanktont).

Diam. cells 15-20 /* ; thickness 8-10 //,.

Beaver dam (rr), Deer (rrr), Sand (2) (IT).

WISCONSIN PHYTOPLANKTON 117

TETRAEDRON TRIGONUM (Nageli) Hansgirg. PI. 23, Figs. 14-16.

Hedwigia 27: 130. 1888.

Polyedrium trigonum Nageli, Gatt. einz. Algen 84, pi. 4, figs. Bla-Blt>. 1849.

Cells medium sized, triangular, flattened. Sides of cells generally
concave, rarely straight. Corners with a single, stout, straight or curved
spine. (Facultative Planktont).

Diam. cells (without spines) 20-30 /*; length spines 8-10 /*.

Crawling Stone (rrr), High (r), Pokegama (1) (rr), Rice (1) (rrr), Ten-
derfoot (rr), Tied Canoe (rrr).

var. SETIGERUM (Archer) Lemmermann. PI. 24, Figs. 1-4.

Arkiv. for Botanik 2, No. 2: 110. 1904.

Tetrapedia setigera Archer, Quart. Jour. Micr. Sci. N. S. 12: 365, pi. 21,
figs. 14-17. 1872; Grevillea 1: 46, pi. 3, figs. 14-17. 1872; G. S. West, Brit.
Freshw. Algae 349. 1904; de Toni, Sylloge algarum 5: 113. 1907.

Polyedrium trigonum var. setigerum (Archer) Schroder, Forschungsbr. a. d.
Biol. Stat. zu Plon 6: 23, pi. I, fig. 6. 1898.

Cells small, triangular, flattened, with a conspicuous emargination
on each side in front view. Corners of cells rounded and produced into
a long delicately tapering spine. Chloroplast single, filling the entire
cell ; with one pyrenoid. (Facultative Planktont).

Diam. cells (without spine) 7-9 /*.; length of spines 12-15 /*.

White Ash (r).

G. S. West and de Toni follow Archer in considering this organism
a member of the Myxophyceae West stating; "T. setigera Archer is a
beautiful little species known from N. W. Scotland and W. Ireland,
which has been erroneously referred by some authors to the chlorophy-
ceous genus Tetraedron. The cell contents of Tetrapedia setigera are
homogeneous and of a pale blue-green color." The cell contents of the
individuals that I have observed are distinctly grass green in color
and contain a single pyrenoid. This pyrenoid has not been noted
by either Archer or Schroder. Since the shape and dimensions of
the ce?.s that I have found are exactly the same as those given by
Archer I believe that I am dealing with the same organism that he
described and one which is a member of the Chlorophyceae and not
the Myxophyceae.

var. GRACILE (Reinsch) de Toni. PI. 24, Figs. 5-9.

Sylloge algarum 1: 598, 1889; Printz, Kgl. Norske Vidensk. Selsk. Skr. 1915,
No. 4: 29, pi. 3, figs. 167-169. 1916.

Polyedrium trigonum var. gracile Reinsch, Die Algenfl. d. mitt. Th. v.
Franken 75: pi. 3, figs, la-lb. 1867.

Tetraedron proteiforme G. M. Smith non (Turner) Brunnthaler, Trans. Wis.
Acad. Sci., Arts, & Lett. 191: 632, pi. 15, figs. 4-5. 1918.

118 WISCONSIN PHYTOPLANKTON

Cells triangular, flattened, concavity of sides very marked. Angles
of cells ending in short spines. Several parietal, disciform chloroplasts
without pyrenoids. (Facultative Planktont).

Cells 23-50 /* broad ; 6-10 /* thick.

Blake (rr), Chain (r), Cochrane (r), Fishtrap (rr), Horse (r), Lac Court
Oreilles (rr), Little Bear (rr), Little Crooked (rrr), Loon (rr), Paddock (rrr),
Palmer (rrr), Rice (1) (rr), Tenderfoot (r), Tied Canoe (rrr), White Ash
(rr), Wolf (rr).

In the second list of Wisconsin algae this alga was given as T. pro-
teiforme but I am now convinced that it is T. trigonum var. gractte.
The cells reach a much larger size than that given by Reinsch and the
excavation of the sides may be very much greater ; in fact the cells are
at times so delicate that they might be placed as Cerasterias species had
not other individuals in the same collection the ordinary cell shape of
T. trigonum var. gracile.

TETRAEDRON MINIMUM (A. Braun) Hansgirg. PI. 24, Figs. 10-13.
Hedwigia 27: 131. 1888; G. S. West, Brit. Freshw. Algae 231, fig. 10lA. 1904.

Cells small, flattened, front view square or oblong with slightly
rounded corners and concave sides. Side view fusiform-elliptic. Wall
smooth or finely granulate. Chloroplast single, parietal, with one
pyrenoid. (Facultative Planktont).

Cells 6-20 IL long, 5-8 ^ thick.

Beaver (2) (rrr), Camp (rr), Deer (rrr), Hillman (rrr), Horse (rr), Little
Bass (2) (rrr), Little Doctor (rr), Mendota (rrr), Okauchee (rrr), Paddock
(rrr), Round (3) (rrr).

TETRAEDRON REGULARS Kiitzing. PI. 24, Fig. 14.

Phycol. germanica 129. 1845.

Polyedrium tetraedricum Nageli, Gatt. einz. Algen 84, pi. 4, figs. BSa-BSb.
1849.

Cells medium sized, tetragonal, generally pyramidal, sides concave,
straight, or slightly convex. Angles with a single, heavy, short, blunt,
spine. ( Tychoplanktont) .

Diam. cells (with spines) 14-45 p.

Blake (rr).

var. INCUS Teiling. PI. 24, Figs. 15-16.

Sv. Bot. Tids. 6: 277, 274, fig. 12. 1912.

Polyedrium regulare Chodat non Kiitzing, Mater, pour la flore crypt. Suisse
I3: 220, fig. 146. 1902.

Cells small, tetragonal, flattened or pyramidal, sides slightly concave.
Angles produced into a single short delicate straight or curved spine.
( Tychoplanktont) .

WISCONSIN PHYTOPLANKTON 119

Diam. cells (without spine) 13-18 /*; length of spines 7-8 //..
Poor Farm (rr).

This is probably what Chodat has figured as T. regulare. It differs
from the typical form in the smaller size, constantly concave sides of
the cell, and the delicate spines at the cell angles.

var. TORSUM (Turner) Brunnthaler. PI. 24, Figs. 17-18.
in Pascher, Siisswasserfl. Deutschl., 6'sterr. u. d. Schw. 5": 150, fig. 169. 1915.

Cells medium sized, tetragonal, with the two halves of the cells
cruciately arranged. Sides of cells straight or convex. Angles of cells
with a single short stout spine (Facultative Planktont).

Diam. cells 25-40 p..

Horse (sss).

Over a hundred individuals were observed in the plankton catch
from this lake and the twisting of the cell halves was a very constant
character.

Tetraedron victorieae var. major var. nov. PI 24, Figs. 19-22;

PI. 25, Fig. 1.

Cells medium sized, four-sided, with two deeply emarginate sides
dividing the cell into two cruciately arranged halves. Sides of cells,
in vertical view, broadly fusiform with acute apices. All angles of
cells with a single heavy straight spine (Euplanktont).

Cells (with spines) 30-60 /* long; 15-20 ^ broad.

Chain (r).

The cell shape and the peculiar twisting of the two halves is identical
with that of T. victorieae Woloszynska (Hedwigia 55: 203, pi. 6, figs.
1-4. 1914) which is known from the plankton of Lake Victoria
Nyanza, Africa. Measurement of about 25 Wisconsin individuals give
the following variation in size, length 30-60 p, breadth 15-20 ; whereas
the length of the African individuals varies from 20 to 30 /* and the
breadth 10-15 fi.

TETRAEDRON VERRUCOSUM G. M. Smith. PI. 25, Figs. 2-3.
Trans. Wis. Acad. Sci., Arts, & Lett. 191: 632, pi. 15, figs. 1-2. 1918.

Cells large, tetragonal, pyramidate, or with the halves cruciate. Sides
convex. Angles of cell terminating in a very heavy, blunt spine. Cell
wall thick, verrucose. (Euplanktont).

Diam. cells (with spines) 65-80 /*; length of spines 13-18 /*,.

Bear (1) (rr).

120 WISCONSIN PH7TOPLANKTON

TETBAEDRON CAUDATUM (Corda) Hansgirg. PI. 25, Figs. 4-7.
Hedwlgia 27: 131. 1888; G. S. West, Brit. Freshw. Algae 231, fig. 101s. 1904.

Cells small, flattened, five-sided; four of the sides concave and the
fifth deeply incised. Angles rounded and produced into a single
straight spine that lies parallel with the flat side of the cell. (Tycho-
planktont).

Diam. cells 6-22 p, ; length of spines 1-3.5 /x..

Chain (rrr), East (rrr), Dutchmans (rrr), Horse (rr), Lake of the Woods
(rrr), Mendota (rrr), Palmer (rrr), Reserve (rrr), Wild Goose (rrr).

The notch at one side of the cell varies considerably in depth but
is always deeper than the incurving of the other four sides.

var. LONGISPINUM Lemmermann. PI. 25, Figs. 8-12.

Bot. Cent. 76: 151. 1898; Forschungsbr. a. d. Biol. Stat. zu Ron 7: 117, pZ. 1,
figs. 8-9. 1899.

Spines on corners at right angles to the flat side of the cell, generally
two pointing in one direction and three in the other. Spines much
longer than in the typical form. (Euplanktont).

Diam. cells (without spines) 8-18 /*; length of spines 3-8 ^.

Pine Tree (r), Travis (sss)

This is a sharply defined variety, differing from the typical form in
the bending of the spines so that they lie at right angles to the plane
of the cell. Lemmermann 's figure 9 shows this very well but for some
reason the cell in his figure 8 has no spines and so is not at all charac-
teristic.

TETRAEDRON PENTAEDRICUM W. & G. S. West. PI. 25, Figs. 13-17.
Trans. Linn. Soc. 2nd Ser. Bot. 5: 84, pi. 5, figs. 15-16. 1895.

Cells small, five-cornered, with four corners in one plane and the fifth
lying at an angle of 30-90 degrees. Corners subacute, each with a
single, short, curved spine. Chloroplast single, parietal, with one pyre-
noid. (Facultative Planktont).

Diam. cells (without spines) 5.5-14 /i, (with spines) 9-20 /*.

Soft (rr).

T. pentaedricum has not been observed since it was described from
Madagascar by the Wests. Chodat considers it a synonym of T. cau-
datum (Corda) Hansg. erroneously citing it as Tetrapedia pentaedri-
cum (Mater, pour la fl. crypt. Suisse 1s: 219. 1902). Isolation of this

WISCONSIN PHYTOPLANKTON 121

alga in pure culture with the retention of its distinguishing character
shows that the Wests are correct in considering it a distinct species.
It resembles T. caudatum in the size, number of corners, character of
spines at the corners, and the concave sides ; but differs in having four
corners in approximately the same plane and the fifth at an angle with
the plane of the other four. There is considerable variation in the
angle at which this fifth corner lies but it is never in the same plane as
the other corners. The Wests (1. c. fig. 17) also describe a variety
minima which, as the name implies, is smaller. I find that the variations
in size of cells of the typical form in a pure culture include the dimen-
sions set for the variety minima so that this variety cannot be recognized.

TETEAEDRON HASTATUM (Eeinsch) Hansgirg. PI. 25, Fig. 18.

Hedwlgia 27: 132. 1888.

Polyedrium tetraedricum var. Hastatum Reinsch, Die Algenfl. d. mitt. Th. v.
Franken 77, pi. 5, figs. 3*-3b. 1867.

Cells medium sized, pyramidate, with the angles produced into long
tapering and somewhat concave processes. Processes unbranched but
having 2 or 3 short spines at the tip. (Tychoplanktont).

Diam. cells (with processes) 28-36 /x; diam. base of process 8 /t.

Horse (rrr).

The general shape of the cell is similar to that of T. limneticum but
there is no branching of the processes.

var. PALATINUM (Schmidle) Lemmermann. PI. 25, Figs. 19-21.

Ber. d. D. bot. Ges. 20: (247). 1902.

Polyedrium Jiastatum var. palatinum Schmidle, Ber. d. D. bot. Ges. 18: 148,
149, pi. 6, figs. 4-5. 1900.

Cells pyramidal, with convex sides, angles produced into fairly deli-
cate non-tapering processes about as long as the diameter of the cells.
Processes unbranched but with three short spines at the apex. (Ty-
choplanktont).

Diam. cells (without processes) 4-14 p.; length processes about 10 /t.

Horse (rr).

The processes at the angles of the cell do not seem as much a part
of the cell as in the typical form. Although both the typical form
and the variety palatinum were found at the same station the two seem
distinct and without transition forms.

122 WISCONSIN PHYTOPLANKTON

Tetraedron constrictum nom. nov. PI. 25, Figs. 22-24.

Tetraedron arthrodesmiforme var. lobulatum Woloszynska, Hedwigia 55:
203, pi. 6, fig. 11. 1914.

Cells medium sized, tetragonal, flattened, two sides straight and two
opposite sides concave. Angles produced into narrow slightly taper-
ing processes which give the cell a decided H-shape. Ends of proc-
esses generally dichotomously branched the branchlets ending in two
short spines. (Euplanktont).

Diam. cells (without processes) 5-8 p.; length 18-25 p.; thickness 8 p..
Length of processes 10-15 p.

Bone (IT).

Woloszynska has found these peculiar H-shaped cells in the plankton
of Lake Victoria Nyanza, Africa and placed them among other varieties
of T. arthrodesmiforme described at the same time. The variety lobu-
latum is, however, sufficiently different from the other varieties to war-
rant raising it to specific rank. Bone lake is the only station where it
has been found but several individuals were seen in the catch from
this lake.

TETRAEDRON GRACILE (Reinsch) Hansgirg. PI. 26, Figs. 1-5.

Hedwigia 28: 19. 1889.

Polyedrium gracile Reinsch, Notarisia 3: 502, pi. 7, figs, la-lc. 1888.

Cells medium size, conspicuously flattened, rectangular, with flattened
sides. Angles of cells produced into narrow processes that generally
branch twice and end in minute spines. The primary branchings of
the processes are at an angle of 90 degrees with one another and always
parallel with a side of the cell. Each cell containing several, parietal
disciform to laminate chloroplasts without pyrenoids. (Euplanktont).

Diam. cells (without processes) 15-30 p.; (with processes) 35-80 p.;
thickness of cells 6-12 p..

Bear (1) (rr), Bear Trap (rrr), Blake (rr), Chain (rr), Elizabeth (rrr),
Hillman (sss), Loon (rrr), Pine (2) (rr), Poor Farm (rr), Round (rr), Travis
(r), Wapagossett (rr).

TETRAEDRON LOBULATUM (Nageli) Hansgirg. PI. 26, Figs. 6-7.

Hedwigia 27: 132. 1888.

Polyedrium lofoulatum Nageli, Gatt. einz. Algen 84, pi. 4, figs. B4a-B4t>. 1849.

Cells medium sized, tetragonal, flattened, or pyramidal. Processes
of angles with one or two short dichotornous branchings that generally
do not end in spines. Sides of cells distinctly concave. Cells contain-

WISCONSIN PHYTOPLANETON 123

ing several parietal disciform chloroplasts without pyrenoids. (Tycho-
planktont).

Diam. cells (with processes) 30-40 p.

Birch Island (rrr), Long (3) (rrr), Sand (2) (rr).

The specimens from Sand lake were of particular interest since three
showed the production of autospores (fig. 6). The chloroplast of old
cells are frequently indistinct but they can be seen quite readily in
young cells.

var. POLYFURCATUM G. M. Smith. PI. 26, Fig. 8.
Bull. Torr. Bot. Cl. 43: 480, pi. 26, figs. 21-22. 1916.

Cells tetragonal, flattened or pyramidal; with concave, straight, or
slightly convex sides. Processes at angles somewhat tapering, 3-5 times
dichotomously branching, the ultimate branchlets with 2-3 minute
spines. (Facultative Planktont).

Diam. cells (without processes) 15-25 /a, (with processes) 35-70 /*.

Beaverdam (r), Blake (rr), Bone (rr), Clare (rr), Fish (rr), Loon (rr),
Muskallonge (rrr), Palmer (r), Pardee (r), Pine Tree (rr), Rice (1) (rr),
Shell (rr), Wild Goose (rrr).

Differing from the typical form in the greater branching of the
processes and from T. enorme (Ralfs) Hansg. in the much longer proc-
esses.

TETRAEDRON LIMNETICUM Borge. PI. 27, Figs. 1-3.

Bet. Not. 1900: 5, pi. 1, fig. 2. 1900; W. & G. S. West, Trans. Roy. Soc. Edin-
burgh 41: 507, pi. 6, figs. 10-11. 1905.

Cells of medium size, tetragonal, pyramidal, the four angles being
produced into one or two dichotomous brandlings. Terminal branch-
lets with 2-3 short spines. (Euplanktont).

Diam. cells (with processes) 45-85 //,; diam. base of processes 8-12 /i.

Chain (rr), Chetek (r), Clear (r), Crawling Stone (rrr), Deer (rr), Diamond
(rrr), Island (rr), Kitten (rr), Little Butternut (rr), Little Crooked (rrr),
Mud (2) (r), Nancy (rr), Palmer (rr), Pine Tree (rr), Poplar (rr), Spirit
(rrr), Squirrel (rr), Wildcat (rr), Wild Goose (rrr), Wolf (rr).

TETRAEDRON PLANCTONICUM G. M. Smith. PI. 27, Figs. 4-5.
Bull. Torr. Bot. Cl. 43: 479, pi. 26, figs. 19-20. 1916.

Cells medium-sized, four to five sided, sides concave to convex. Angles
of cells produced into narrow, once to twice dichotomously branchec

processes. Ultimate branchlets with 2-3 short spines. Processes ^^Q^

in front view, narrow in side or vertical view. (Euplanktont). Xj*/

124 WISCONSIN PHYTOPLANKTON

Diam. cells (without processes) 18-30 /x; (with processes) 45-60 /*.

Cranberry (rr), Cochrane (rr), Devils (2) (sss), Granite (rr), Horseshoe
(1) (rr), Lindy (rrr), Lost (rr), No Mans (rr), Prairie (rr), Rock (rr), Ver-
milion (r).

The chief difference between this species and T. limneticum is the
greater size of the cells in proportion to the length of the processes.

TETRAEDRON ENORME (Ralfs) Hansgirg. PI. 27, Fig. 6.
Hedwigia 27: 132. 1888; G. S. West, Brit. Freshw. Algae 231, flg. lOlo. 1904.

Cells irregularly tetrahedric, angles produced into short processes
and sides emarginate. Processes generally bilobed and ending in short
spines. (Tychoplanktont).

Diam. cells 25-45 /*,.

Carson (rr), Cochrane (rr), Devils (2) (r), Horse (rrr), Horseshoe (2)
(rrr), Lake of the Woods (rrr), Okauchee (rrr), Pine (2) (rr).

POLYEDRIOPSIS Schmidle 1899.

Cells solitary, generally tetragonal, flattened; rarely pyramidal cr
with sides cruciate. Corners truncate and with 3-10 long, hyaline,
slightly tapering setae. Chloroplast parietal or entirely filling the
cell, pyrenoid single.

Reproduction by the formation of 2-4-8 autospores through the divi-
sion of the cell contents.

POLYEDRIOPSIS SPINULOSA Schmidle. PI. 27, Figs. 7-8.

Allg. Bot Zeitschr. 5: 17. 1899.

Tetraedron spinulosum Schmidle, ibid. 2: 193, fig. 2. 1896.

Characters the same as those of the genus. (Euplanktont).
Greatest diameter of cells 12-25 n ; length of setae about 40 /*.

Horse (rr), Prairie (rrr).

The general tendency among phycologists is to follow Wille's prac-
tice and place the alga in a special sub-genus of Tetraedron. The
setae on the cell angles are of the same type as those found on Lager-
Jieimia and Micractinium so that Polyedriopsis forms, in my opinion,
a genus parallel with Tetraedron just as Lagerheimia does with Oocystis.

WISCONSIN PHYTOPLANKTON 125

\

Sub-family MICE ACT 'INIEAE.

Cells solitary or in colonies; spherical or ovoid; with long hyaline
setae or spines completely covering or restricted to certain parts of the
cell wall. Chloroplast single and cup-shaped ; or laminate to disciform
and from one to several in each cell. Chloroplasts generally with pyre-
noids.

KEY TO THE GENERA.
Cells spherical.

Cells organized into definite colonies MICRACTINIUM (p. p.)

Cells solitary.

Wall covered with fine hair-like setae.

Setae thickened in lower third ACANTHOSPHEAERA

Setae not thickened in lower third GOLENKINIA

Wall covered with delicately tapering spines ECHINOSPHAEKEIXA

Cells ovoid.

Cells organized into definite colonies MICRACTINIUM: (p. p.)

Cells solitary.

Setae somewhat tapering LAGERHEIMIA

Setae not tapering FRANCEIA

MICRACTINIUM Fresenius 1858.

Cells spherical or ovoid, in colonies of 4-32 or more, generally quad-
rately arranged in one plane but sometimes tetrahedrically disposed.
Cell wall delicate, with 1-7 long hyaline setae that are not thickened
at the base lying on the free surface of the cells. Chloroplast single,
parietal, cup-shaped ; with one pyrenoid.

Reproduction by the division of contents of any cell to form a 4- or
8-celled autocolony, the young colony being liberated by a rupture of
the mother cell wall into four parts. Young coenobia frequently re-
maining attached to the parent coenobe for some time.

KEY TO THE SPECIES.

Cells spherical M. PUSILLUM

Cells ovoid M. QUADEISPINUM

MICRACTINIUM PUSILLUM Fresenius. PI. 28, Figs. 1-3.

Abh. Senckenb. Naturf. Ges. 2: 236, pi. 11, figs. 46-49. 1858; G. M. Smith, Bull.
Torr. Dot. Cl. 43: 477, pi. 25, fig. 18. 1916.

Richteriella ~botryoides (Schmidle) Lemmermann, Hedwigia 37: 307, pi. 10,
figs. 1-6. 1898.

Richteriella botryoides forma fcnestrata Chodat, Mater, pour la flore crypt.
Suisse I3: 194, fig. 110. 1902.

126 WISCONSIN PEYTOPLANETON

Richteriella botryoides forma tetraedrica Lemmermann, Arch. f. Hydrobiol.
u. Planktonkde. 5: 307. 1910.

Colonies of 4-8-16 or more cells in groups of four and disposed in a
quadrate or pyramidate manner with the groups of four in turn pyra-
midately or quadrateiy arranged. Cells spherical, with 1-5 long, hya-
line, delicately tapering setae on the face not adjacent to other cells.
Chloroplast single, parietal, cup-shaped; with one pyrenoid. (Eu-
planktont).

Diam. cells (without setae) 3-7 /*; length of setae 20-35 /*,.

Blake (rrr), Bone (sss), Chain (sss), Chetek (rr), East (IT), Green (1)
(rr), Hooker (rr), Horse (rr), Horseshoe (2) (rrr), Island (rrr), Little Bass
(2) (r), Little Crooked (rrr), Loveless (r), Mendota (rr), Monona (cc), North
Turtle (rr), Pokegama (3) (rr), Poor Farm (rr), Pope (rr), Prairie (rr),
Round (1) (rr), Tenderfoot (rrr), Tied Canoe (rr), Wolf (rrr).

Flat sixteen-celled colonies with a central open space are the most
common. Such colonies have been given the form name fenestrata but
both it and the form tetraedrica are unworthy of recognition. On rare
occasions large colonies are found; colonies containing over 750 cells
having been collected from the plankton of Lake Monona.

var. ELEGANS G. M. Smith. PI. 29, Fig. 1.
Trans. Wis. Acad. Sci., Arts, & Lett. 191: 631, pi. 12, fig. 4. 1918.

Cells with 5-7 setae on the exposed face. Dimensions as in the
typical form. (Euplanktont).

Rice (1) (rr).

This seems to be a distinct variety since the cells of colonies from
this lake all bore the large number of setae.

MICRACTINIUM QUADRISETUM (Lemmermann) G. M. Smith. PI. 28,

Fig. 4.

Bull. Torr. Bot. Cl. 43: 479, pi. 25, fig. 17. 1916.

Cells ovoid, with 1-4 long, delicately tapering setae on the exposed
faces. Chloroplast single, parietal, cup-shaped; with one pyrenoid.
(Euplanktont).

Diam. cells (without setae) 4-7 ^, length 8-10 /x; length of setae
23-40 p.

Bear Trap (rrr), Camp (rr), Cranberry (rrr), Eagle (rrr).

The cells of this species are somewhat larger than those of M. pusH-
lum and are distinctly ovoid. The character upon which the specific

WISCONSIN PHYTOPLANETON 127

name is based is quite misleading since the number of setae may vary
from one to four. Colonies containing more than sixteen cells have
not been observed and the cell arrangement has been quadrate in every
ease.

GOLENKINIA Chodat 1894.

Cells spherical, normally solitary; occasionally forming temporary
colonies. Cell wall thin, sometimes enclosed in a thin gelatinous en-
velope. Surface of cell covered with hyaline setae that are slightly
tapering but not conspicuously thickened in the lower third. Chloro-
plast single, parietal and cup-shaped or entirely filling the cell; pyre-
noid single.

Eeproduction by the formation of autospores. Zoospores have been
reported but their formation is doubtful.

KEY TO THE SPECIES.

Setae 25-45 fj, long G. RADIATA

Setae 12-18 /j, long G. PAUCISPINA

GOLENKINIA RADIATA Chodat. PL 29, Figs. 2-3.
Jour, de Bot. 8: 305, pi. 3, figs. 1-24. 1894.

Cells spherical, solitary, sometimes in temporary colonies of four
cells. Entire cell wall covered with long, delicate, hyaline setae. Chlor-
oplast single, cup-shaped, parietal ; with one pyrenoid. (Euplanktont) .

Diam. cells (without setae) 7-15 /*; length setae 25-45 /*.

Green (2) (rrr), White Ash (rr).

This and the following Golenkinia species have been made a sub-
genus of Micractiniwn by Wille and that terminology followed in the
second list but the colonial and solitary habit seem to me sufficiently
diverse to warrant generic distinction.

GOLENKINIA PAUCISPINA W. & G. S. West. PI. 29, Figs. 4-5.
Trans. Roy. Irish Acad. 32, Sec. B: 68, pi. 1, flg. 18. 1902.

Cells solitary, spherical, with few to fairly numerous, short, delicately
lapering, hyaline or dark setae. Chloroplast single, completely filling
the cell, with one pyrenoid. (Euplanktont).

Diam. cells (without setae) 15-18 p.; length setae 12-18 /u,.

Prairie (rr).

The setae of the cells in Prairie lake were more numerous than the
"Wests found them in individuals from the plankton of Lough Neagh,

128 WISCONSIN PHYTOPLANKTON

Ireland. They were also dark colored and are more conspicuous than
in other members of the Micractineae.

ACANTHOSPHAERA Lemmermann 1899.

Cells spherical, solitary, with a single cup-shaped chloroplast con-
taining one pyrenoid. Cell wall thin, without a gelatinous sheath;
covered with many long hyaline setae that are thicker in the lower
third and then abruptly diminish to a very fine hair.

Method of reproduction unknown.

ACANTHOSPHAERA ZACHAEiASi Lemmermann. PI. 29, Figs. 6-8.
Forschungsbr. a. d. Biol. Stat. zu Plon 7: 118, pi. 1, figs. 10-11. 1899.

Characters as those of the genus. (Euplanktont).

Diam. cells (without setae) 9-14.5 /n; length setae 30-35 /*.

Horse (rr).

The chief distinction between this genus and Golenkinia is the thick-
ening of the lower part of the setae.

Echinosphaerella gen. nov.

Cells spherical, solitary. Cell wall thin, completely covered with
heavy, long, hyaline, delicately tapering and slightly concave, homo-
geneous spines. Chloroplast single, parietal, cup-shaped; with one
pyrenoid.

Reproduction unknown.

Echinosphaerella limnetica sp. nov. PI. 29, Figs. 9-11.

Characters as described above. (Euplanktont).
Diam. cells (without spines) 9-12 /*. Spines 2.5-3 ^ broad at base,
20-25 v long.

Horse (rr).

The alga at once suggests a desmid zygospore, especially those of
certain Staurastrum species. In all desmid zygospores the chloroplast
is not definite and since the alga collected from Horse Lake has a
single, well defined, cup-shaped chloroplast with one pyrenoid the pre-
sumption is that it is a vegetative cell and not a zygospore. The
nearest genus is Echinosphaeridium Lemmermann where the setae
covering the wall have a broad tapering gelatinous sheath at the base.
In Echinospliaerella there is not a central hair-like seta with a gelati-
nous covering, but a homogeneous spine of considerable thickness at the

WISCONSIN PHYTOPLANKTON 129

base. Although the genus is provisionally placed in the Micractinieae
its spines are quite different from those of other genera of the sub-
family.

LAGERHEIMIA Chodat 1895.

Cells solitary; ovoid, ellipsoid, or citriform. Cell wall firm, without
a gelatinous sheath; with long tapering setae that lie a short distance
back from the poles or cover the entire wall. Chloroplasts 1-4, pari-
etal, laminate ; with or without pyrenoids.

Eeproduction by autospores that are generally liberated at once but
which may remain inside the old mother wall a short time.

KEY TO THE SPECIES.

Setae covering entire cell wall L. DROESCHEM

Setae confined to poles of the cell.

Cells lemon-shaped L. CITBIFOBMIS

Cells ovoid.

Length of setae more than double that of cell L. LONGISETA

Length of setae less than double that of cell.

2-4 setae at each pole L. SUBSALSA

3-8 (generally 6) setae at each pole L. CILIATA

LAGERHEIMIA CILIATA (Lagerheim) Chodat. PI. 31, Figs. 1-2.

Nuova Notarisia 10: 90. 1895.

Oocystis ciliata Lagerheim, ofvsers Kgl. Vet.-Ak. Forh. 39, No. 2: 76, pi. 3,
figs. 33-37. 1882.

Chodatella ciliata (Lag.) Lemmermann, Hedwigia 37: 310. 1898.

Cells oblong-ovoid, with 3-7, hyaline, delicately tapering setae at
each pole. Chloroplasts 1-4, parietal, laminate; each with a single
pyrenoid. ( Euplanktont) .

Breadth of cells (without setae) 6-18 p; length (without setae) 10-
21 p. Setae 15-20 p long.

Kegonsa (IT), Mendota (sss).

The setae of this species are not in definite whorls but distributed over
the entire polar region.

var. minor (G. M. Smith) comb. nov. PI. 31, Fig. 3.

Chodatella ciliata var. minor G. M. Smith. Bull. Torr. Bot. Cl. 43: 477,
pi. 25, fig. 16. 1916.

Cells ovoid, with 6-8 setae at each pole. (Euplanktont).
Diam. cells (without setae) 6-7.5 p; length (without setae) 8-10 p.
Setae about 20 p long.
Muskallonge (rr).

9

130 WISCONSIN PETTOPLANKTON

LAGERHEIMIA SUBSALSA Lemmermann. PI. 30, Figs. 3-4.

Forschungsbr. a. d. Biol. Stat. zu Flon 6: 193, pi. 5, figs. 2-6. 1898.
Chodatella subsalsa Lemmermann, Hedwigia 37: 310. 1898.

Cells ovoid, with 2-4 delicate setae at each pole. Chloroplast single,
laminate, parietal; with one pyrenoid. (Euplanktont).

Diam. cells (without setae) 2.5-8 /i; length (without setae) 5-12 /x.
Setae 7.5-26 p. long.

Deer (rrr), Geneva (rr).

LAGERHEIMIA LONGISETA (Lemmermann) Printz. PI. 30, Figs. 8-9.

Skr. Vidensk. i Kristiania, Mat.-Naturv. Kl. 19131, No. 6: 60. 1914.

Chodatella longiseta Lemmermann, Hedwigia 37: 310, pi. 10, figs. 11-18.
18'98.

Cells ellipsoid, with a whorl of 4-10 long, hyaline, delicately tapering
setae a short distance from each pole. Chloroplast single ( ?), parietal ;
without a pyrenoid (?). (Euplanktont).

Breadth of cells (without setae) 5-8 /*; length (without setae) 9-13 u.
Setae 40-55 p. long.

White Sand (sss).

The exceedingly long setae at once distinguish the species from all
others. The arrangement of the setae in a whorl is best seen in an end
view of a cell.

var. major var. nov. PI. 30, Figs. 10-12.

Cells ovoid, with somewhat pointed ends. With a whorl of 4-7 setae
u short distance from each pole. Cells containing 1-2 laminate pari-
etal chloroplasts each with a single pyrenoid. (Euplanktont).

Breadth of cells (without setae) 12-15 p.; length (without setae)
15-22 ^ Setae 45-60 /* long.

Blake (rr), Little Bass (2) (rrr).

The variety is distinguished from the typical form by the more
pointed and larger cells.

Lagerheimia citriformis (Snow) comb. nov. PI. 30, Figs. 1-2.

Chodatella citriformis Snow, Bull. U. S. Fish Comm. 22: 389, pi. 2, figs.
S'-S8. 1903.

Cells ovoid to ellipsoid, with a small obtuse projection at each pole.
Poles with a whorl of 4-8 long, hyaline, delicately tapering setae at the

WISCONSIN PHYTOPLANETON 131

base of the polar projections. Chloroplast single, parietal; with one
pyrenoid. ( Euplanktont ) .

Breadth cells (without setae) 8-20 /A; length (without setae) 13-23 p.
Setae 25-35 /* long.

Horse (rrr), Kegonsa (rrr).

This is the only species with polar projections that resemble the
polar nodules of Oocystis.

LAGERHEIMIA DROESCHERI (Lemmermann) Printz. PI. 30, Figs. 5-7,

Skr. Vidensk. i Kristiania Mat.-Naturv. Kl. 19131, No. 6: 60. 1914.

Chodatella Droescheri Lemmermann, Ber. d. D. Bot. Ges. 18: 98, pi. 3, fig. 12.

1900.

Cells ovoid to ellipsoid; with numerous hyaline delicately tapering
setae covering the entire wall. Cells with 2-4 parietal, laminate
chloroplasts ; each with a single pyrenoid. (Euplanktont).

Breadth of cells (without setae) 5-12 /<.; length (without setae) 9-16
fj.. Setae 15-22 /* long.

Horse (rrr), Travis (r), Upper Nashotah (rr).

FRANCEIA Lemmermann 1898.

Cells ovoid, solitary or in colonies of 2-4; free-floating. Cells en-
closed in a delicate gelatinous sheath (?). Entire cell wall covered
with delicate hyaline setae that do not taper. Chloroplasts 1-3, pari-
etal, laminate, with or without pyrenoids.

Reproduction by autospores.

FRANCEIA OVALIS (France) Lemmermann. PI. 31, Fig. 4.

Hedwigia 37: 308. 1898.

Phythelios ovalis Franc6, Notarisia 1894: 2, figs. 1-5. 1894.

Cells ovoid to elliptic; with two chloroplasts. (Euplanktont).
Breadth of cells (without setae) 7-10 /*; length (without setae) 13-
17 /i. Setae 15-23 /* long.

Pine Tree (rr).

The minimal dimensions given above are somewhat smaller than those
given by France but I feel that the Wisconsin organism should not be
considered a distinct variety until the variation in size of the typical
form has been determined more fully.

The recognition of the genus Franceia is open to question since the
characters upon which Lemmermann bases the genus (number of

132 WISCONSIN PHYTOPLANKTON

chloroplasts, presence of a vacuole, and cell division in one plane) are
ones which might be found in any Lagerheimia species. The setae,
however, are very delicate and do not taper so that the genus is pro-
visionally considered distinct from Lagerheimia.

Sub-family SELENASTREAE.

Cells elongate, straight or curved; with finely pointed ends or with
ends rounded. Solitary or associated in colonies containing an indefi-
nite number of cells. Colonies with or without a gelatinous envelope.
Cells generally with one parietal chloroplast that is with or without
pyrenoids.

KEY TO THE GENERA.
Cells solitary.

Ends of cells produced into setae SCHROEDERIA

Ends of cells not produced into setae.

Chloroplast with, an axial row of pyrenoids CLOSTEBIOPSIS

Chloroplast never with more than a single pyrenoid . ANKISTBODESMUS (p. p. )
Cells in colonies.

Colonies not enclosed in a gelatinous sheath.
Cells straight, in loose fasiculate bundles or spirally

twisted around one another ANKISTBODESMUS (p. p.)

Cells curved, with convex faces towards one another SELENASTRUM

Colonies enclosed in a gelatinous sheath.

Cells curved KIBCHNERIELLA

Cells straight.

Colonies with cells in groups of two ELAKTOTHBIX

Colonies with cells in groups of 2-4-8 QUADBIGETLA

SELENASTRUM Reinsch 1867.

Cells broadly to narrowly acicular, semilunar; joined by their con-
vex faces into colonies of 4-8-16 or more cells without a gelatinous en-
velope. Chloroplast single, parietal, laminate, on convex side of young
cells ; entirely filling older cells ; with one pyrenoid.

Reproduction by any cell forming 2-4-8 autospores which, when
liberated, have the arrangement of the cells in an adult colony. Auto-
spores remaining attached to parent colony for some time.

The statement is generally made that there are not more than six-
teen cells in a colony but I have found that in the plankton of Wiscon-
sin lakes the colonies sometimes contain over a hundred cells.

WISCONSIN PHYTOPLANKTON 133

KEY TO THE SPECIES.

Cells arcuate, never sickle-shaped S. WESTH

Cells arcuate to sickle-shaped.

Diameter of cells not exceeding 5 n S. GRACELE

Diameter of cells 5-8 p S. BIBBAIANUM

SELENASTRUM GRACILE Reinsch. PI. 31, Fig. 5.
D. Algenfl. d. mitt. Th. v. Franken 65, pi. 4, figs. 3a-3i>. 1867.

Cells lunate to sickle-shaped, quite narrow in proportion to their
length. Apices of cells acute. Chloroplast single, laminate, parietal,
on convex side of cell. Without a pyrenoid. (Facultative Planktont).

Diam. cells 3-5 /*; length 15-30 p.. Distance between apices 8-20 p.

Bear (3) (rr), Chain (rr), Hillman (rrr), Horse (rr), Monona (r),
Pokegama (1) (rr), Prairie (rr), Upper Turtle (rrr), Whitefish (rr).

Differs from the next species in the more delicate cells. Possibly it
should be considered a variety of S. Bibmianum and not a distinct
tpecies.

SELENASTRUM BIBRAIANUM Reinsch. PI. 31, Figs. 6-7.
D. Algenfl. d. mitt. Th. v. Franken 64, pi. 4, figs. 2*^-2*. 1867.

Cells in spherical to ovoid colonies of 4-8-16 or more with their con-
vex sides facing the center of the colony. Cells crescent-shaped to
sickle-shaped, gradually tapering to a fairly sharp apex. Chloroplast
parietal, on convex side of and almost filling the cell ; pyrenoid single.
( Facultative Planktont ) .

Diam. cells 5-8 p. ; length 20-38 p.. Distance between apices 5-25 /*.

Beaverdam (rr), Blake (rrr), Bone (rr), Deer (rrr), Little Bass (2) (rrr).
Loveless (rr), Mendota (rrr), Meta (r), Nancy (rr), Pewaukee (rr), Pine
Tree (rr), Poor Farm (rr), Rice (1) (rr), Spirit (rrr), Squirrel (rrr), Ten-
derfoot (rr), Travis (rr), White Ash (sss), Wolf (rr).

All descriptions of S. Bibraianum state that there are but four or
eight cells in the colony but I have found that in Wisconsin lakes there
may be over a hundred cells in the colony, the number of cells usually
ceasing to be a multiple of two after there are more than sixteen cells
in the colony.

Selenastnun Westii sp. nov. PI. 31, Figs. 8-10.

Selenastrum acuminatum G. S. West non Lagerheim, Jour, of Bot. 50: 88,
•figs. 5a-5s. 1912.

Colonies of 2-4-8 cells irregularly arranged with their convex sides
in apposition. Frequently dissociating into the individual cells when

>j WISCONSIN PHYTOPLANKTON

: •.) i

-.r.ature. Cells 1'inate to arcuate, never sickle-shaped; gradually taper-
mg to a sharp point. Chloroplast single, parietal on convex side of cell ;
without a pyrenoid. (Facultative Planktont).
Diain. cells 1.5-2.6 p. Distance between apices 15-18 p..

DeviLs (1) (rr).

The cells of this species are quite like those of Scenedesmus acumi-
natus (Lagerheim) Chodat but their organization in the colony is quite
different. West has recently investigated an organism which he con-
siders identical with the Selenastrum acuminatum described by Lager-
heim. I have obtained West's organism in pure culture and find that
the cell shape and colony organization is as he describes. The fortunate
rediscovery of Lagerheim 's species from the plankton of Horse Lake
shows that in the organization of the colony it is a Scenedesmus and
that Chodat is entirely correct in removing the species from Selenast-
rum. The organism that West found is, on the other hand, a true
Selenastrum but is not the species which Lagerheim erroneously re-
ferred to Selenastrum.

ANKISTRODESMUS Corda 1838.

Cells acicular to fusiform ; straight, lunate, or sigmoid ; ends of ceils
gradually tapering to a point; solitary or loosely aggregated without
order in temporary colonies that are not embedded in a gelatinous en-
velope. Chloroplast single, parietal, sometimes fragmented into small
pieces ; with or without a pyrenoid.

Reproduction by the formation of several autospores in any cell.

KEY TO THE SPECIES.

Cells twisted around one another A. SPIRAUS

Cells not twisted around one another A. FALCATUS

ANKISTRODESMUS FALCATUS (Corda) Ralfs. PI. 32, Fig. 1.

Brit. Desmidieae 180, pi. 34, figs. 3"-3b. 1848; G. S. West, Brit. Freshw. Algae
223, fig. 94A. 1904.

Cells acicular to narrowly fusiform, tapering very gradually to acute
apices, lunate or slightly arcuate. Length 12-24 times the diameter.
Seldom solitary, generally loosely associated in fasiculate bundles.
Chloroplast single, generally without pyrenoids. (Facultative Plank-
tont) .

Diam. cells 1.5-3.5 /* ; length 20-80 ^

Fence (rrr), Half Moon (rrr), Horse (rr), Kawaguesaga (rrr), Lac du
Flambeau (rrr), Little Crooked (rr), Lost (rr), Oconomowoc (rrr), Pine

WISCONSIN PHYTOPLANKTON 135

Tree (rr), Poor Farm (rr), Poplar (rr), Rock (1) (rr), Tenderfoot (rr),
White Ash (rr).

var. ACICULARIS (A. Braun) G. S. West.
Brit. Freshw. Algae 223, figs. 94e-94c. 1904.

Cells usually solitary, straight or slightly curved, apices acutely at-
tenuated. Chloroplast single, parietal, with or without a pyrenoid.
Cells 2.5-4 p. broad, 36-65 n long.

Beaverdam (rr), Little Bass (1) (rrr), Mendota (rr), Rice (1) (rr), Wau-
besa (rrr).

var. TUMIDUS (W. & G. S. West) G. S. West. PI. 32, Fig. 2.
Brit. Freshw. Algae 224, fig. 94o. 1904.

Cells solitary or in small aggregates, straight or curved, inflated at
the middle and with acute apices. Chloroplast single, parietal, with
or without pyrenoids. (Tychoplanktont).

Cells 4.5-6.5 p. broad ; 61-73 ^ long.

Devils (1) (rrr), Mendota (rr).

var. MIRABILIS (W. & G. S. West) G. S. West. PI. 32, Figs. 3-5.
Brit. Freshw. Algae 224, fig. 94s. 1904.

Cells solitary, straight, lunate, or sigmoid; with acute apices; much
longer and narrower than the typical form. Chloroplast single, com-
monly fragmented by large vacuoles in the cytoplasm; without pyre-
noids. ( Euplanktont ) .

Cells 2-3.5 //, broad ; up to 150 ^ long.

Bear (3) (rr), Bryer (rr), Chain (sss), Crab (rrr), Devils (1) (sss),
Devils (2) (rr), Dummy (rr), High (rr), Horseshoe (1) (rr), Reserve (rr),
Squirrel (rr), Travis (rrr), Whitefish (rr).

ANKISTRODESMUS SPIRALIS (Turner) Lemmermann. PI. 32, Figs. 6-7.

Arch. f. Hydrobiol. u. Planktonkde. 4: 176. 1908.

Raphidium spirale Turner, Kgl. Sv. Vet.-Ak. Handl. 25, No. 5: 156, pi. 20,
fig. 26. 1892.

Ankistrodesmus falcatus var. spiralis (Turner) G. S. West, Brit. Freshw.
Algae 224. 1904.

Cells acicular, attenuated to acute apices ; in colonies of four or eight
and spirally twisted around one another in the middle of the cell but
with the extremities free. Chloroplast single, completely filling the
cell; without a pyrenoid (?). (Tychoplanktont).

136 WISCONSIN PEYTOPLANKTON

Cells 1-2.5 fi broad ; 20-40 p long.
Grassy (rr), Silver (2) (rrr).

G. S. West places the alga as a variety of A. falcatus but the twist-
ing of the cell seems to be such a constant character that I have fol-
lowed Lemmermann 's practice in considering it a distinct species.

CLOSTERIOPSIS Lemmermann 1898.

Cells solitary, acicular, with ends produced into very acute apices,
without a gelatinous envelope. Chloroplast single, not interrupted
at the center of the cell, occupying the greater portion of the cell and
containing a single axial row of about a dozen pyrenoids.

The genus is very closely related to Ankistrodesmus, differing only
in the greater length of the cells and the axial row of pyrenoids. It
also resembles certain Closterium species but the chloroplast of Closter-
ium is always interrupted at the center of the cell. Many feel that the
single species is not sufficiently differentiated to warrant its separation
from Ankistrodesmus.

CLOSTERIOPSIS LONGISSIMA var. TROPICA W. & G. S. West. PI. 32, Fig. 8.

Trans. & Proc. Bot. Soc. Edinb. 23: 31, pi. 1, fig. 1. 1905.

Rhaphidium longissimum var. tropicum W. & G. S. West, Trans. Linn. Soc.
2nd. .Ser. Bot. 6: 198. 1902.

Cells acicular, poles acute but not ending in a point of hair-like fine-
ness. (Facultative Planktont).

Cells 6-7.5 fjL broad ; 225-370 ^ long.

North Turtle (rr).

The dimensions of specimens that I have found agree with those given
for individuals from Ceylon but not with those from the Scotch plank-
ton.

SCHKOEDERIA Lemmermann 1898.

Cells solitary, straight or curved, acicular; with one apex produced
into a fine seta tapering to a point, the other with a slightly broader
projection terminating in a small disc. Cells without a gelatinous en-
velope. Chloroplast single, parietal, laminate ; with one pyrenoid.

Method of reproduction unknown.

WISCONSIN PHYTOPLANETON 137

SCHROEDERIA SETiGERA (Schroder) Lemmermann. PI. 32, Fig. 12.

Hedwigia 37: 311. 1898; G. M. Smith, Bull. Torr. Bot. Cl. 43: 473, pi. 24,

fig. 8. 1916.

Length of cells 15-20 times breadth. (Euplanktont).
Cells 3-6 /t broad, 60-85 p. long (with spines). Length of spines
13-27 p..

Chain (sss), Devils (1) (c), Long (2) (rr), Sand (1) (rr).

This peculiar alga has the general appearance of a Characium. Al-
though hundreds of individuals have been found, it has never been
found attached to other algae or to crustaceans so that it seems safe
to assume that it leads a free-floating and not an epiphytic existence.
The disc at one end of the setae described above has not been observed
by other investigators, possibly because the alga is very minute.

Reproductive stages have never been found so that the systematic
position of the genus is doubtful. Judging by the cell shape it is a
close relative of Ankistrodesmus, a genus to which it has been referred
by some.

SCHROEDERIA JUDAYI G. M. Smith. PI. 32, Figs. 9-11.

Bull. Torr. Bot. Cl. 43: 474, pi. 24, figs. 9-11. 1916.

Cells smaller than the foregoing. (Euplanktont).
Cells 2.5-6 p broad, 45-63 /* long (with spines). Length of spines
10-16 ft.

Amicoy (rr), Birch (rrr), Camp (rr), Delavan (rr), Kawaguesaga (rr),
Mendota (sss), Prairie (rr), Round (1) (rrr), St. Croix (rr).

QUADKIGULA Printz 1915.

Cells generally in groups of 2-4-8 with their long axes parallel to
the long axis of the colony and enclosed by a hyaline, homogeneous,
gelatinous sheath. Colonies ellipsoid, 2-5 times as long as broad. Cells
cylindrical to fusiform, 4-7 times as long as broad, straight or slightly
curved. Chloroplast single, filling most of the cell; with or without
pyrenoids.

Reproduction by 2-4-8 autospores from each cell, the fasiculate group
of autospores frequently remaining within the envelope of the mother
colony for some time.

]38 WISCONSIN PHYTOPLANKTON

KEY TO THE SPECIES.

Ends of cells rounded Q. PFITZERI

Ends of cells pointed.

Chloroplast notched at the center Q. CHODATI

Chloroplast not notched at the center Q. LACUSTBIS

Quadrigula Pfitzeri (Schroder) comb. nov. PI. 33, Figs. 1-2.

Rhaphidium Pfitzeri Schroder, Verh. d. Nat.-Med. Ver. zu Heidelberg N. F.
7: 152, pi. 6, fig. 6. 1902.

Ankistrodesmus Pfitzeri (Schrode-) G. S. West, Brit. Freshw. Algae 224,
figs. 94G-34H. 1904.

Cells about 7 times as long as broad, central portion cylindrical with
ends slightly tapering and rounded. Chloroplast generally filling the
entire cell, with or without a pyrenoid. (Euplanktont).

Breadth of cells 3-6 p., length 22--4S (generally about 35) /*.

Bear (1) (IT), Beaverdam (rr), Blake (IT), Chain (rr), Clear (rr),
Cochrane (sss), Devils (1) (s), Fishtrap (rrr), Found (r), Fowler (rr),
Harris (rr), Hillman (ss), Jennie (rr), Lac Court Oreilles (rr), Lindy (rr),
Long (2) (rrr), Little Wood (rr), Mud (1) (rr), Mudhen (rr), Oconomowoc
(rr), Okauchee (rr), Palmer (sss), Pardee (rr), Pine Tree (r), Poplar (r),
Reserve (rr), Rice (1) (rr), Sand (1) (rr), Shell (rr), Sishebogema (rr),
Travis (rr), White Ash (r), Whiteflsh (rr), Wild Goose (rrr).

The chief characteristic of the genus is the arrangement of the cells
in groups of 2-4-8 with their long axes parallel to the long axis of the
colony, together with the gelatinous envelope that surrounds the colony.
Admitting the generic validity of Quadrigula, Ankistrodesmus Chodati
and A. lacustris are in a much more natural position when placed with
Quadrigula species.

Quadrigula Chodati (Tanner-Fullman) comb. nov. PI. 33, Fig. 3.

Raphidium Chodati Tanner-Fullman, Bull. Herb. Boiss. 2 Ser. 6: 156, figs.
1-11. 1906.

Ankistrodesmus Chodati (Tanner-Fullman) Brunnthaler, in Pascher, Siiss-
wasserfl. Deutschl., osterr. u. d. Schw. 52: 193, fig. 306. 1915.

Cells linear, arcuate, or lunate ; fusiform and tapering to sharp ends.
Longitudinally arranged in a gelatinous colony of 4-8-16 or more cells.
Cells with a single, parietal, laminate chloroplast that is notched at
the center and contains two pyrenoids. (Euplanktont).

Breadth of cells 3.5-7 /*, length 30-80 ^ Colonies up to 50x250 M.

Boulder (r), Little Bass (2) (rrr), Lac du Flambeau (rr), Sand (3) (ss).

Tanner-Fullman states that the cells are always lunate but those that
I have observed were always straight or slightly curved. The notching
of the chloroplast together with the two pyrenoids is such a distinct

WISCONSIN PHYTOPLANKTON 139

feature that there can be no doubt of the identity of the Wisconsin alga
with his species.

Quadrigula lacustris (Chodat) comb. nov. PI. 33, Figs. 4^6.

Raphidium Braunii var. lacustre Chodat, Bull. Herb. Boiss. 5: pi. 11, figs.
9-10. 1897; Mater, pour la fl. crypt. Suisse I3: 200, fig. 117. 1902.

AnTcistrodesmus lacustre (Chodat) Ostenfeld, Hedwigia 46: 384. 1907.

Cells spindle-shaped, straight, with pointed ends. Cells rarely soli-
tary, generally irregularly distributed throughout, or in groups with
their long axes parallel to the long axis of the fusiform gelatinous
colonial envelope. Chloroplast single, parietal, laminate, at one side
of the cell or spirally twisted; generally with a single pyrenoid. (Eu-
planktont).

Cells 3-5 fi broad, 20-25 /* long.

Blue Gill (rr), Browns (rr), Clear Crooked (cc), Green (2) (rr), Horseshoe
(1) (rr), Lynx (rr), Pokegama (2) (rr), Round (1) (rrr).

ELAKTOTHRIX Wille 1898.

Cells fusiform when mature, longitudinally arranged in pairs within
a fusiform homogeneous gelatinous matrix. Chloroplast single, laminate,
parietal, with one or two pyrenoids. Colonies epiphytic when young
and free-floating when mature ; or free-floating throughout the life of
the plant.

Reproduction by a transverse division into two daughter cells which
remain unchanged for some time. Akinetes known.

Wille first placed the alga as a close relative of Actinastrum Hantz-
schi Lagerheim, but later thought it a relative of Coccomyxa Schmidle
(Wille, in Engler & Prantl, Nat. Pflanzenfam. I2 (Nachtr.) : 36, figs.
18A-18E. 1909) ; Pascher (Susswasserfl. Deutschl., Osterr. u. d. Schw.
52: 220, figs. 25-26. 1915) places it among the algae of doubtful sys-
tematic position; while G. S. West (Algae 1: 202. 1916) thinks it
closely allied to Ankistrodesmus, a view which seems to me most logical
since Ankistrodesmus, Quadrigula and Elaktothrix form a very natural
evolutionary series.

KEY TO THE SPECIES.

Both poles of cells acute E. VIRIDIS

One pole of cell acute, the other generally rounded E. GELATINOSA

ELAKTOTHRIX GELATINOSA Wille. PI. 34, Figs. 1-3.

Biol. Cent. 18: 302. 1898; in Engler & Prantl, Nat. Pflanzenfam. 1s (Nachtr.) :
3G, figs. 18A-18E. 1909; W. & G. S. West, The Naturalist, 19O9: 2-91, figs. GA-SD.
1909.

Colonies free-floating, elongate fusiform to somewhat irregular ; with

140 WISCONSIN PH? TO PL AN ETON

the long axes of the cells parallel to the long axis of the colony. Cells
lying in pairs, spindle-shaped; generally with one pole rounded and
the other pointed. The rounded ends of a pair of cells in apposition.
Chloroplast single, parietal, laminate; with one pyrenoid. Colonies
rarely containing over fifty cells. (Euplanktont).

Cells 3-6 p broad; 15-25 /* long. Colonies 10-30 p. broad; 70-160
fi long.

Crooked (rrr), Deer (rrr), Hillman (rr), Jag (rrr), Jennie (rr), Long (2)
(rrr), Long (3) (rr), Loon (rrr), Mudhen (rr), Pine (2) (rrr), Sand (2)
(rrr), Streitor (sss).

The dimensions of the cells and the general appearance of the colony
in individuals that I have found is more like the Wests' description of
the alga as found in England. Wisconsin colonies rarely contain more
than sixteen cells.

ELAKTOTHRIX VIRIDIS (Snow) Printz. PI. 33, Fig. 7.

Skr. Vidensk. i Kristiania Mat.-Naturv. Kl. 19131: No. 6: 31, pi. 1, figs. 9-12.
1914.

Fusola viridis Snow, Bull. U. S. Fish Comm. 22: 389, pi. 2, figs. VP-VP. 1903.

Colony free-floating or epiphytic, fusiform or irregular; gelatinous
sheath of colony sharply defined, frequently showing remains of old
cell wall at apex. Cells broadly fusiform, straight or sigmoid, with
acute apices. Chloroplast single, completely filling the cell; with one
or two pyrenoids. (Tychoplanktont).

Cells 6-15 /* broad, 12-35 /* long.

Soft (rr).

KIRCHNERIELLA Schmidle 1893.

Cells lunate to sickle-shaped with their apices almost touching; or
elongate, vermiform, arcuate, or spiral cylinders with rounded ends.
Associated without definite arrangement in colonies enclosed by a hya-
line, homogeneous, gelatinous envelope. Number of cells in young
colonies a multiple of two, in older colonies indefinite but rarely more
than seventy-five. Chloroplast single, parietal, on convex side of or
entirely filling the cell ; generally with a single pyrenoid.

Reproduction by the division of any cell to form four or eight auto-
spores that are liberated by a rupture of the old mother cell wall but
remain within the gelatinous envelope of the colony.

WISCONSIN PHYTOPLANKTON 141

KEY TO THE SPECIES.

Cells lunate to sickle-shaped.

Ends of cells pointed K. LUJTARIS

Ends of cells rounded K. OBJCSA

Cells arcuate, spiral, or vermiform cylinders.

Breadth of cells 2 ^ or less K. CONTORTA

Breadth of cells over 2 /j. K. ELONGATA

KIRCHNERIELLA LUNARis (Kirchner) Mobius. PI. 34, Fig. 4.

Abh. d. Senckenb. Naturf. Ges. 18: 331. 1894; Chodat, Mater, pour la fl. crypt.
Suisse I3: 202, figs. 12r-1218. 1902.

Cells flattened, crescent-shaped, with apices some distance apart,
about twice as long as broad, ends tapering to a blunt point; irregu-
larly arranged in groups of four to eight within the gelatinous colonial
envelope. Chloroplast single, filling the entire cell with the exception
of a small part on the concave side; pyrenoid single. (Facultative
Planktont).

Cells 3-8 n broad, 6-15 p. long ; colonies up to 250 p in diam.

Bear (3) (rr), Beaverdam (rr), Birch Island (rrr), Blake (rr), Chain (ss),
Chetek (rr), Cochrane (rr), Crab (rrr), Deer (rr), Devils (2) (rr), Duck
(rr), Dummy (sss), Elizabeth (rr), Green (2) (rr), High (rr), Hillman (r),
Horseshoe (1) (rr), Jag (rr), Lindy (rrr), Little Crooked (rrr), Little Doc-
tor (rr), Long (3) (rrr), Loveless (rr), Lower Turtle (rrr), Lynx (rrr), Men-
dota (rr), Meta (rr), Mud (2) (rr), Nancy (sss), North Twin (rrr), Paddock
(rr), Pardee (rr), Pine Tree (rr), Pokegama (1) (r), Pokegama (3) (sss),
Poplar (rr), Prairie (sss), Round (3) (rrr), St. Croix (r), Shell (r), Spirit
(rrr), Squirrel (rr), Upper Turtle (rrr), White Ash (rr).

The species differ from K. obesa in the pointed ends of the cells. The
two are widely distributed plankton .organisms but have never been
found in quantity in any lake of the state.

var. DIANAE Bohlin. PI. 34, Fig. 5.
Bih. Kgl. Sv. Vet.-Ak. Handl. 23, Afd. 3, No. 7: 20, pi. I, figs. 28-30. 1897.

Cells curved until the apices are almost touching, apices more pointed
and frequently slightly twisted. (Facultative Planktont).
Cells 3-5 p broad, 10-21 /t long.

Hillman (rr), Pine (2) (rr), White Ash (r).

The cell shape of this variety resembles that of Selenastrum but the
colony differs in being enclosed by a gelatinous envelope. The apices
are much sharper than in the typical form.

WISCONSIN PEJTOPLANKTON

var. irregularis var. nov. PI. 35, Fig. 1.

Apices of cells twisted and frequently not pointing in the same direc-
tion. (Facultative Planktont).
Cells 4r-6 /A broad, 6-13 ^ long.

Cochrane (rr), Pokegama (1) (r), Tenderfoot (rr).

Although the cell apices of K. lunaris var. dianae are sometimes not
in the same plane, they never exhibit the twisting found in this variety.
The twisting of the cells of this variety is similar to that of K. contorta
but they have the shape and pointed ends that characterize K. lunaris.

KIRCHNERIELLA OBESA (W. West) Schmidle. PI. 35, Figs. 2-3.

Ber. d. Naturf. Ges. zu Freiburg i. B. 7: 16 (83). 1893; G. S. West, Brit.
Freshw. Algae 226, figs. 96A-96B. 1904.

Cells flattened with outer side markedly convex and inner sides
parallel, ends rounded and tapering slightly. Chloroplast single, fill-
ing the entire cell with the exception of a small portion on the con-
cave side; with one pyrenoid. (Facultative Planktont).

Cells 3-8 /i broad, 6-16 M long.

Bear (2) (rr), Bear Trap (rr), Camp (rr), Catherine (rr), Center (r),
Chain (rr), Chetac (r), Crawling Stone (rrr), Devils (1) (rrr), Hillman (rr),
Kitten (rr), Lac Court Oreilles (ss), Lac du Flambeau (rr), Mendota (r),
Palmer (rrr), Pine Tree (rr), Pokegama (2) (rr), Poor Farm (rr), Reserve
(rr), Rice (1) (rr), Rock (rrr), Sand (4) (rr), South Turtle (rr), White-
fish (rrr), Wildcat (rr), Winnebago (rr).

The cells of this species might be described as thick discs incised a
third to a half the width of the cell did not other members of the genus
show that this effect is produced by a curving of the cell.

var. MAJOR (Bernard) G. M. Smith. PI. 35, Fig. 4.
Trans. Wis. Acad. Sci., Arts, & Lett. 191: 636, pi. 10, fig. 7. 1918.

Inner face between cell apices curved; apices not close together,
rounded and slightly tapering. (Facultative Planktont).
Cells 3-5 n broad, 8-21 p. long.

Carson (rr), Lac Court Oreilles (r), Wolf (rr).

This variety has a large open space between the apices whereas in
the typical form this space is narrow and with parallel sides. The cells
are also much narrower in proportion to their length. Brunnthaler
(in Pascher, Siisswasserfl. Deutschl. Osterr. u. d. Schw. 52: 180. 1915)
has placed the alga as a form of K . lunaris var. dianae but the cell apices
are too rounded to consider it a variety of K. lunaris.

WISCONSIN PET TOPLAN ETON 143

var. APERTA (Telling) Brunnthaler. PI. 35, Figs. 5-6.

in Pascher, Siisswasserfl. Deutschl. b'sterr. u. d. Schw. 52: 182, fig. 268. 1915.
Kirchneriella aperta Telling, Sv. Bot. Tlds. 6: 276, fig. 9. 1912.

Cells with blunt, rounded apices, concave side between apices broadly
V-shaped. (Facultative Planktont).
Diam. cells 6-12 /x.
Diamond (rr), Palmer (SB).

KIRCHNERIELLA CONTORTA (Schmidle) Bohlin. PI. 35, Fig. 7.

Bin. Kgl. Sv. Vet.-Ak. Handl. 23, Afd. 3, No. 7: 20. 1897.

Kirchneriella obesa, var. contorta Schmidle, Flora 78: 44, pi. 1, fig. 2. 1894.

Cells cylindrical, arcuate or in spirals that never make more than
iy2 turns; ends rounded, not tapering. Cells generally lying some
distance from one another within the homogeneous colonial envelope.
Chloroplast single, filling the entire cell, without a pyrenoid. Cells
sometimes spirally arranged in the colony; rarely more than sixteen
cells in a colony. (Facultative Planktont).

Cells 0.7-2.0 fi broad, 8-14 /x long ; colonies up to 60 p. in diam.

Chain (rrr), Clear (rr), Cochrane (rr), Fowler (rrr), Mendota (rrr), Par-
dee (rr), Pine Tree (rrr), Poor Farm (rrr).

A species which at first glance does not appear related to K. lunaris
and K. obesa, but which at times shows a certain resemblance to
K. obesa var. major. It and the following species are rare algae in
Wisconsin. They are closely related, the chief difference being the
smaller size and fewer number of cells in the colony of K. contorta.

KIRCHNERIELLA ELONGATA G. M. Smith. PI. 36, Figs. 1-2.
Bull. Torr. Bot. Cl. 43: 473, pi. 24, fig. 1. 1916.

Cells elongate-cylindrical with rounded ends ; spirally or irregularly
twisted. Colonies of 4-8-16 or more cells arranged in a snarl at the
center of a copious homogeneous gelatinous sheath. Chloroplast single,
parietal; without a pyrenoid. (Facultative Planktont).

Cells 2-3 fi broad, 15-25 /* long ; colonies up to 100 p. in diam.

Devils (2) (rrr), Horse (rrr), Lac Court Oreilles (rr), No Mans (rr),
Palmer (rr), White Ash (sss).

Sub-family CRUCIGENIEAE.

Cells acicular, fusiform, ovoid, triangular, or trapezoidal; in flat
coenobia with the number of cells always a multiple of two. Cells
quadrately arranged in coenobe or in a linear series. Coenobe gener-
ally without a gelatinous envelope. Chloroplasts 1-4, parietal, disci-
form or laminate ; generally with one pyrenoid.

144 WISCONSIN PHTTOPLANKTON

KEY TO THE GENERA.

Cells quadrately arranged.

Quadrate arrangement apparent in front view of cells.

Outer face of cells without spines CBUCIGENIA

Outer face of cells with spines TETBASTBUM

Quadrate arrangement apparent in end view of cells TETBADESMXJS

Cells arranged in a linear series SCENEDESMUS

CRUCIGENIA Morren 1830.

Coenobe free-swimming, of four cells quadrately arranged with a
quadrangular open space at the center and frequently connected to
other coenobia by a gelatinous envelope or the remains of the old mother
cell walls. Multiple coenobia forming a flat plate one cell in thickness
and containing 4, 16, 32, 64 or more cells. Cells flattened; ovoid, tri-
angular, trapezoidal, or semicircular in front view; with a smooth cell
wall. Chloroplasts l^i, parietal, disciform to laminate, with or with-
out pyrenoids.

Reproduction by autocolony formation, the four cells of the coenobe
generally producing autocolonies at the same time.

KEY TO THE SPECIES.

Cells apiculate C. APIOULATUM

Cells not apiculate.
Coenobe with a large rectangular open space at the center.

Front view of cells trapezoidal C. FENESTBATA

Front view of cells semicircular C. LAUTEBBOBNEI

Coenobe with a small open space at the center.
Length of coenobe greater than the breadth.
Wall of cell the same thickness throughout.

Outer face of cells concave C. CBUCIATA

Outer face of cells convex.

Cells of coenobe regularly arranged C. RECTANGUIABIS

Cells of coenobe irregularly arranged C. IBBEGULABIS

Wall of cell thicker at the poles C. TBU^CATA

Length of coenobe the same as the breadth.

Cells triangular, with fairly acute corners C. TETBAPEDIA

Cells spherical to triangular, with rounded corners C. QUADBATA

CRUCIGENIA RECTANGULARIS (Nageli) Gay. PI. 36, Fig. 3.

Recherches sur le. dev. et la class, de quelques algues vertes 100, pi. 15, fig. 151.
1891.

Coenobe four-celled, cells in mutual contact at the poles and sides
and with a small rectangular open space at the center. Generally
united in compound coenobia containing an indefinite number of coen-

WISCONSIN PHYTOPLANKTON 145

obes. Cells ovoid to elongate-ovoid, with 1-4 parietal, disciform chloro-
plasts, each with a single pyrenoid. Old mother cell wall frequently
enclosing young coenobia for some time. (Facultative Planktont).
Cells 4-7 p broad, 5-10 p. long.

Bear (2) (rr), Beaverdam (rr), Big (rrr), Birch Island (rrr), Devils (1)
(r), Fowler (rrr), Half Moon (rr), Hillman (rr), Kegonsa (rr), Lac Court
Qreilles (rr), Lindy (rr), Little Bass (2) (rr), Little Doctor (rr), Mill (rrr),
Nancy (rr), Nicaboyne (rr), Okauchee (rrr), Old Taylors (rr), Pine Tree
(rr), Sand (1) (rr), Upper Nashotah (rrr), Winnebago (rr).

CRUCIGENIA IRREGULARIS Wille. PI. 36, Figs. 4-5.

Biol. Cent. 18: 302. 1898; Nyt. Mag. f. Naturvidensk. 38: 10, pi. 1, fig. 15,
1900; W. & G. S. West Trans. & Proc. Bot. Soc. Edinburgh 23: 29, pi. 1, figs.
6-7. 1905.

Coenobia four-celled, with cells in contact at sides and poles, at other
times without a definite arrangement. Coenobia irregularly combined
into multiple coenobia. Cells ovoid ; with 1-4 parietal, disciform chloro-
plasts; with or without pyrenoids. (Facultative Planktont).

Cells 4-9 fj. broad, 6-14 p. long. Coenobia 8-14 «. broad. 15-30 //, long.

Browns (rr), Camp (rr), Fish (rr), Horseshoe (2) (rr), Mudhen (rr),
Reserve (rr), Sand (3) (sss).

The cell shape is quite similar to that of C. rectangularis but the ar-
rangement of cells within the coenobe is very irregular in about half
the colonies one meets with. This irregular cellular arrangement coup-
led with the larger cell size warrants the separation of the alga from
C. rectangularis. The alga is generally reported to be without pyre-
noids but I have frequently found them in the chloroplasts of C. irregu-
laris.

CRUCIGENIA CRUCIFERA (Wolle) Collins. PI. 36, Fig. 6.

Tufts, coll. studies 2: 170. 1909.

Staurogenia crucifera Wolle, Bull. Torr. Bot. Cl. 6: 140. 1877.

Staurogenia cruciatum Wolle, Freshw. Algae of U. S. 171, pi. 157, figs. 9-11.
1887.

Coenobia four-celled, rhomboidal, with rounded ends, slightly con-
cave sides, and a small rectangular open space at the center. Cells
elongate, outer face concave, inner and those in contact with other cells
straight. Chloroplast single, parietal, laminate; without a pyrenoid.
(Facultative Planktont).

Cells 3.5-5 p. broad, 5-7 p. long. Coenobia 9-11 p. broad, 14-16 p. long.

Hillman (rr), Tenderfoot (rr).

The arrangement of the individual coenobia into compound coenobi*
is generally that which Wolle gives in his figure 9 of Staurogenia cruci-

10

146

WISCONSIN PHTTOPLANKTON

atum. CoUin's surmise that the reported cruciform marking of the
cell wall is probably due to a division of the cell contents is correct and
what Wolle calls the cell is in reality the coenobe. The remains of the
old cell walls play an important part in binding together the various
coenobia of the multiple coenobe.

Crucigenia truncate sp. nov. PI. 36, Figs. 7-9.

Coenobe four-celled, with a small rectangular space at the center and
held in compound coenobia of indefinite size by the remains of old
mother cell walls. Cells quadrately arranged with bases and middle
third of inner sides in mutual contact but with apices and outer faces
free. Cells elongate, ovoid, with free ends truncate. Cell wall at free
apex thicker than in other parts. Chloroplasts 1-4, parietal, disci-
form, without pyrenoids. (Euplanktont).

Cells 4-6 p. broad, 6-10 /* long. Coenobia 6-12 p broad, 12-20
H long. Compound coenobia up to 50x75 p..

Chain (rr), Hillman (rr), Pine Tree (rr), Travis (rr).

The species is differentiated by its flattened cell apices and the thicker
walls at the apices. The cells are always regularly arranged within the
coenobe, but when in compound coenobia the arrangement is frequently
irregular.

CRUCIGENIA APICULATA (Lemmermann) Schmidle. PI. 37, Fig. 1.

Allg. Bot. Zeitschr. 6: 234. 1900.

Staurogenia apiculata Lemmermann, Bot. Cent. 76: 151. 1898; For-
Bchungsbr. a. d. Biol. Stat. zu Plon 7: 119, pi. 1, fig. 14. 1899; Snow, Bull.
U. S. Fish Comm. 22: 376, pi. 1, figs. V^V9. 1903.

Tetrastrum apiculatum (Lemmermann) Brunnthaler, in Pascher, Siisswas-
serfl. Deutschl., cistern u. d. Schw. 52: 177, fig. 258. 1915; G. M. Smith, Bull.
Torr. Bot. Cl. 43: 472, pi. 24, fig. 3. 1916.

Coenobia four-celled, embedded in a delicate gelatinous sheath. Cells
quadrately arranged with their long axes parallel and a small rectangu-
lar space at the center. Coenobia generally in multiple coenobia which,
when containing large numbers of coenobia, are frequently irregular.
Cells ovoid to triangular, with a short conical projection at the free
apex and frequently another one at the side of the base away from the
center of the coenobe. Each cell containing 1-4 parietal disciform
chloroplasts with one pyrenoid. (Euplanktont).

Cells 3-7 fj, broad, 5-10 /* long. Coenobia 6-12.5 /* broad, 9-18
fi long. Compound coenobia up to 150 p broad.

Mendota (rrr), Palmer (rrr), South Crab (rr).

The cells of 16-celled multiple coenobia are regularly arranged but
when multiple coenobia contain 150-200 cells the arrangement is fre-

WISCONSIN PHYTOPLANKTON 147

quently irregular. The gelatinous sheath enclosing the colony is very
delicate and can only be seen when properly stained. This species was
placed in the genus Tetrastrum in a preliminary list, but it is more
closely related to Crucigenia than to Tetrastrum.

CRUCIGENIA QUADRATA Morren. PI. 36, Figs. 10-14.

Ann. Sci. Nat. 20: 415, pi. 15, figs. 1-5. 1830.

Staurogenia triangularis Chodat, Mem. Herb. Boiss. 1, No. 17: 7, figs. 14-19.
1900.

Crucigenia triangularis (Chodat) Schmidle, Allg. Bot. Zeitschr. 6: 234. 1900.

Staurogenia multiseta var. punctata Schmidle, Ber. d. D. bot. Ges. 18: 157,
pi. 6, figs. 13-14. 1900.

Coenobia four-celled, circular in outline. Cells in mutual contact at
or with very small rectangular openings at center of the coenobe.
Four coe'nobia compressed to form rectangular multiple coenobia which
in turn are joined to other sixteen-celled multiple coenobia. Cells
spherical to triangular; with a smooth wall or with 1-6 minute knob-
like projections on the wall. Chloroplasts 1-4, parietal, disciform, with
or without pyrenoids. (Facultative Planktont) .

Cells 2.5-6 p. broad, 3-7 /* long. Coenobia 5.5-17 p. in diam. 16-
celled compound coenobia 12-30 /* in diam.

Carson (rrr), Chain (rr), Hillman (sss), Kitten (rrr), Lac du Flambeau
(IT), Palmer (sss), Pardee (rr), Tenderfoot (rrr), White Sand (rrr).

Pyrenoids are very prominent in the chloroplasts of certain colonies
while other colonies collected from the same station show no trace of
them. In some of the colonies from Hillman lake small, globular, but-
ton-like structures were observed on the cell walls. Such structures
have been noted by Schmidle and form the distinctive character of his
variety punctata of Staurogenia multiseta [Tetraslrum multisetum
(Schmidle) Chodat]. If the variety is to be recognized it should be
called C. quadrat a var. punctata (Schmidle) but I am of the opinion
that it is not a sufficiently constant character to warrant recognition.
There is likewise no justification for considering C. triangularis (Cho-
dat) Schmidle a distinct species since it does not differ in any respect
from C. quadrata.

CRUCIGENIA TETRAPEDIA (Kirchner) W. & G-. S. West. PI. 37, Fig. 2.

Trans. Roy. Irish Acad. 32, Sec. B: 62, pi. 1, figs. 11-12. 1902.

Staurogenia tetrapedia Kirchner, Jahreshefte d. Ver. f. Vaterl. Naturk. i.
Wiirttemberg 1880, pi. 2, fig. 1.

Tetrapedia emarginata Schroder, Ber. d. D. bot. Ges. 15: 492, pi. 25, figs.
6a-6c. 1897.

Lemmermannia emarginata (Schroder) Chodat, Mem. Herb. Boiss. 1, No.
J7; 5, figs. 1-8. 1900.

148 WISCONSIN PHYTOPLANKTON

Lemmermannia tetrapedia (Kirchner) Lemmermann, Arkiv. for Botanik 2,
No. 2: 157. 1904.

Coenobia four-celled, with, a very small rectangular open space at
the center. Frequently joined in multiple coenobia of sixteen cells that
may be connected in turn to other 16-celled multiple coenobia. Cells
flattened, triangular, with rounded corners. Cell contents homogeneous,
or with a single parietal chloroplast, with or without pyrenoids. (Fac-
ultative Planktont).

Diam. cells 4.8-9.5 p.; diam. coenobia 8-15 p.; diam. 16-celled multiple
coenobia up to 40 /*.

Palmer (rr).

Certain investigators have noted that the cell contents are at times
absolutely homogeneous. This has caused Schroder to consider the alga
a species of Tetrapedia, one of the Myxophyceae, but the Wests have
given cogent reasons for considering it a Crucigenia. I have found a
distinct parietal chloroplast and pyrenoid in the cells whereas Chodat
states that there is a chloroplast but no pyrenoid. His founding of the
genus Lemmermannia upon this single character (lack of a pyrenoid)
has rightly been called by G. S. West (Brit. Freshw. Algae 217. 1904)
"the climax of absurdity."

CRUCIGENIA FENESTRATA Schmidle. PI. 37, Fig. 3.

Allg. Bot. Zeitsckr. 6: 234. 1900.

Staurogenia fenestrata Schmidle, Allg. Bot. Zeitschr. 3: 107, fig. 1. 1897.

Coenobia four-celled, rectangular, with a medium-sized opening at
the center; with an inconspicuous gelatinous sheath. Frequently in
multiple coenobia with the component coenobia lying close together.
Cells trapezoidal, with the longest face at the outside of the coenobe.
Chloroplast single, except just before division, parietal, without a pyre-
noid (?). (Euplanktont).

Cells 3-5 ju, broad, 5-12 /* long ; coenobia 8-14 /* broad.

Bettin'e (rr), White Sand (rr).

The specimens that I have found do not agree in all respects with
Schmidle 's description since there was no gelatinous sheath surround-
ing the coenobe and filling the central space.

CRUCIGENIA LAUTERBORNEI Schmidle. PI. 37, Fig. 4.

Allg. Bot. Zeitschr. 6: 234. 1900.

Staurogenia Lauterbornei Schmidle, Allg. Bot. Zeitschr. 2: 192, fig. 1. 1896.

Coenobia four-celled, cells in contact with one another at their apices
only and with a large square open space at the center of the coenobe.

WISCONSIN PHYTOPLANKTON 149

Coenobia joined in multiple coenobia of at least sixteen cells by the re-
mains of old cell walls and a gelatinous envelope. Cells flattened, sub-
hemispherical in front view with the flattened side towards the center
of the coenobe. Chloroplast single, parietal, on the outer face of the
cell; with one pyrenoid. (Euplanktont).

Cells 4.5-9 /A broad, 8-15 /* long. Coenobia 15-25 /* in diam ; multiple
coenobia up to 150 /* in diam.

Kegonsa (r), Fokegama (rr), Rice (1) (r), Upper Turtle (r).

A very distinct species and one that is readily recognized by the large
opening at the center of the colony. C. fenestrata also has a large, rec-
tangular open space at the center of the coenobe but the two species
have quite differently shaped cells ; those of C. Lauterbomei being semi-
circular in front view, and those of C. fenestrata trapezoidal.

TETEASTRUM Chodat 1895.

Coenobia four-celled, with cells cruciately arranged in a flat plate;
at times embedded in a thin gelatinous envelope. Cells triangular to
ovoid, with several spines or setae on the free face. Chloroplasts 1-4,
parietal, disciform, with or without pyrenoids.

Reproduction by autocolony formation in any cell.

The genus is closely related to Crucigenia, differing only in the spines
on the margins of the cells and an absence of an association in multiple
coenobia.

TETRASTRUM STAUROGENIAEFORME (Schroder) Lemmermann. PI. 37,

Figs. 5-6.

Ber. d. D. bot. Ges. 18: 95. 1900.

Cohniella Staurogeniaeformis Schroder, Ber. d. D. bot. Ges. 15: 373, pi. 17,
fig. 5. 1897.

Coenobia four-celled, with a very minute open space at the center
of the colony. Coenobe embedded in a very delicate gelatinous envelope.
Cells cruciately arranged, triangular, with 5-6 very delicate setae on
the free surface. Chloroplasts 1-4, parietal, disciform, with or without
pyrenoids. ( Euplanktont ) .

Diam. cells (without setae) 3-6 /*; diam. coenobia (without setae)
7-15 fi. Setae 4-8 /* long.

Horse (rr), Mendota (rrr).

The setae on the outer face of the cells are very delicate and easily
overlooked. If the setae are not taken into consideration the alga looks
exactly like Crucigenia quadrata.

150 WISCONSIN PHYTOPLANKTON

TETRADESMUS G. M. Smith 1913.

Colonies free-floating, four-celled, rarely two- or three-celled. Cells
in two planes with two cells in each plane and joined along the long
axes when the colony is viewed from the side. Viewed from the top
cells quadrately arranged. Cells elliptic-fusiform to broadly elliptic,
with outwardly divergent or straight apices. Chloroplast single, pari-
etal and laminate or completely filling the cell ; pyrenoid single, central
or eccentric.

Reproduction by autocolony formation in any cell of the colony, the
young coenobia being liberated by a rupture of the mother cell wall.

TETRADESMUS WISCONSINENSIS G. M. Smith. PI. 37, Figs. 7-11.
Bull. Torr. Bot. Cl. 40: 76, pi. 1, figs. 1-2, 3-20. 1913.

Cells elliptic-fusiform, apices attenuated and outwardly divergent.
Pyrenoids eccentric. (Facultative Planktont).
Cells 4-6 p. broad, 12-14.5 /* long.

Blake (rrr), Mendota (rr), Nancy (rrr).

SCENEDESMUS Meyen 1829.

Coenobe a flat (rarely curved) plate of ellipsoidal, ovoid, or acicular
cells with cell number always a multiple of two. Cells in lateral con-
tact and in one or two rows. Cell wall smooth, corrugated, granulate,
or spicate ; with or without marginal or lateral teeth or spines. Chloro-
plast single, parietal, and laminate in young cells; frequently filling
entire cell in older colonies ; pyrenoids single, central or eccentric.

Reproduction by autocolonies from any or all cells of the coenobe,
the number of cells in the colony not necessarily the same as that of
the mother colony.

KEY TO THE SPECIES.

Walls smooth, without granulations, lateral ridges, terminal teeth or spines.
Cells acicular to broadly elliptic, with pointed ends.
Colony a flat plate.

All cells in colony erect S. OBLIQUTJS

Median cells erect, terminal cells lunate S. DIMOBPHTJS

Colony a curved or twisted plate.

Cells forming a curved surface S. ACTJMINATUS

Cells alternately arranged with terminal cells not in the

same plane as the others S. BEBNABDH

Cells ovoid to cylindrical, with rounded ends.
Arrangement of cells a single linear or subalternating but

never a double series S. BIJUGA

Arrangement of cells a double linear series S. ABCUATUS

WISCONSIN PH7TOPLANKTON 151

Wall variously sculptured or ridged, at times with terminal teeth, or spines.
Longitudinal ridges on sides of the cells.

Without terminal teeth or spines S. ACUTTFORMIS

With terminal teeth or spines.

Terminal cells with long spines at poles S. ABMATUS

All cells with short teeth at poles S. BRASILIENSIS

Longitudinal ridges not present on sides of the cells.

Teeth-like spines covering entire wall S. HYSTBIX

Teeth or spines confined to poles, outer face of terminal
cells, or middle of all cells.

Cells with short teeth at poles S. DENTICTJLATUS

Cells with long spines.
Spines on both median and terminal cells.
Poles of cells only region bearing spines.

Cells ovoid to ovoid-cylindrical S. LONGUS

Cells naviculoid S. OPOLTENSIS

Poles and median part of cells bearing spines S. ABUNDANS

Spines confined to terminal cells.

Cells ovoid to ovoid-cylindrical S. QTJADBICAUDA

Cells naviculoid S. OPOLIENSIS

SCENEDESMUS OBLJQUUS (Turpin) Kiitzing. PI. 37, Figs. 12-14.
Linnaea 8: 609. 1833; G. S. West, Brit. Freshw. Algae 220, fig. 92A. 1304.

Cells of 2-4-8 cells arranged in a single linear or sublinear series.
Cells fusiform, with acute apices ; interior cells with straight sides, outer
face of terminal cells slightly' concave, straight, or convex. Cell wall
smooth, without terminal teeth or spines. (Tychoplanktont).

Cells 3-9 fjL broad, 10-21 p. long. 4-celled coenobia 10-21 /* broad,
12.5-24 /* long.

Balsam (rrr), Bear (1) (rrr), Blake (rr), Bone (rr), Grassy (rr), Hill-
man (rrr), Horseshoe (2) (rrr), Lindy (rr), Little Bear (rrr), Little Doctor
(rr), Little Rice (2) (rrr), Loon (rr), Mendota (rrr), Pewaukee (rrr), Poor
Farm (rrr), Pope (rrr), Rice (2) (rr), Sand (3) (rrr), Sand (4) (rrr), Up-
per Nemahbin (rrr), White Ash (rrr).

SCENEDESMUS DIMORPHUS (Turpin) Kiitzing. PI. 37, Figs. 15-17.

Linnaea 8: 608. 1833; G. M. Smith, Trans. Wis. Acad. Sci., Arts, & Lett. 182:
434, pi. 32, figs. 185-189; pi. 33, figs. 190-195. 1916.

Coenobia of four or eight cells arranged in a linear or alternating
series. Cells fusiform with apices attenuated to delicate points. In-
terior cells erect, outer erect or markedly lunate. Cell wall smooth,
without terminal teeth or spines. (Facultative Planktont).

Cells 2-5 ft broad, 18-23 ^ long. 4-celled coenobia 18-23 ^ broad,
12-25 p. long.

Dunham (rrr), Horse (r), Pine Tree (sss), Poor Farm (ss), Travis (sss).

152 WISCONSIN PHYTOPLANETON

The outwardly turned lunate terminal cells, together with the pro-
nounced alternate arrangement distinguishes this species from the fore-
going. I have given elsewhere (1. c.) the reasons for considering this
a distinct species and not a variety of S. obliquus.

SCENEDESMUS ACUMiNATus (Lagerheim) Chodat. PI. 38, Figs. 1-4.

Mater, pour la fl. crypt. Suisse I3: 211. 1902.

Selenastrum acuminatum Lagerheim 6'fvers. Kgl. Vet.-Ak. Forh. 39: No. 2:
71, pi. 3, figs. 27-30. 1882.

Coenobia curved, of 4 or 8 (generally 4) cells. All of the cells of a
colony arcuate or lunate, fusiform, with the ends gradually tapering
to a fine point. Cell wall smooth, without teeth, granulations or spines.
(Facultative Planktont).

Cells 3-7 yu. broad, 30-40 /x, between apices.

Horse (sss).

This species should not be confused with Selenastrum acuminatus
G. S. West non Lagerheim, a species which I have already discussed
in connection with Selenastrum Westii G. M. Smith.

SCENEDESMUS BEENARDII G. M. Smith. PI. 38, Figs. 5-9.
Trans. Wis. Acad. -Sci., Arts, & Lett. 182: 436, pi. 33, figs. 196-208. 1916.

Colonies of 2-4US cells. Interior cells fusiform, lunate or sigmoid,
with acute apices; alternately arranged with apices in contact with
apices or median portion of adjacent cells. Terminal cells fusiform to
lunate, frequently at an angle to the plane of the coenobe, in contact
with the interior cells by the apex only. Cell wall smooth, without
terminal spines or teeth. ( Tychoplanktont ?).

Cells 3-6 p. broad, 8-17 p. long.

Monona (rrr).

SCENEDESMUS BIJUGA (Turpin) Lagerheim. PI. 37, Figs. 18-20.

Kuova Notarisia 1893: 158. 1893.

Scenedesmus Ujugatus (Turpin) Kiitzing. G. S. West, Brit. Freshw. Algae
220, fig. 92c. 1904.

Coenobes flat, of 2-4-8 cells in a single (rarely subalternate) series.
Cells oblong-elliptic to ovoid, with broadly rounded ends. Cell wall
smooth, without teeth or spines. (Tychoplanktont).

Cells 4-7 /x broad, 7-18 /* long. 4-celled colonies 7-18 /i broad, 16-25

M long-
Fowler (rrr), Lindy (rr), Little Rice (2) (rr), Mill (rr), Poplar (rrr),
Silver (2) (rr), Streitor (rr), Upper Turtle (rrr), Wolf (rr).

WISCONSIN PHYTOPLANETON 153

var. ALTERNANS (Eeinsch) Borge. PI. 38, Figs. 10-11.

Arkiv. for Botanik 6, No. 1: 57. 1906.

Bcenedesmus alternans Reinsch, Abh. Senckenb. Naturf. Ges. 6: 135, pi. 20,
fig. De. 1866.

Colonies flat, generally 8-celled, with a very marked alternate ar-
rangement of the component cells. Cells ovoid to elliptic. (Tycho-
planktont) .

Cells 4-8 n broad, 6-15 p. long. 8-celled coenobia 12-30 /* broad,
22-45 ft long.

Blake (rr), Devils (1) (rrr), Muskallonge (rr).

Since cultural studies have shown that the alternate arrangement cf
cells is a constant character it is proper to consider this a distinct vari-
ety. The variety has also been found in lakes where the typical form
is absent.

SCENEDESMUS ARCUATUS Lemmermann. PI. 38, Figs. 12-14.
Forschungsbr. a. d. Biol. Stat. zu Plon 7: 112, pi. 1, figs. 2-4. 1893.

Colonies always curved, of 4-8-16 (generally 8) cells arranged in a
double row. Cells ovoid, sometimes angular by mutual compression
at the base. Coenobia with small interstices between the cells. Cell
wall smooth, without spines or teeth. (Euplanktont).

Cells 3-9 (i broad, 9-17 p long. 8-celled coenobia 15-25 /* broad,
15-40 p. long.

Beaverdam (rr), Blake (rrr), Camp (rrr), Center (ss), Chain (rr),
Cochrane (rr), Cranberry (rr), Hillman (r), Lac Court Oreilles (rr), Lac du
Flambeau (rr), Little Bass (2) (rr), Little Crooked (rr), Long (1) (rrr),
Long (3) (rr), Lower Turtle (rr), Mendota (sss), Meta (rrr), North Turtle
(rr), Owen (rrr), Paddock (rrr), Palmer (rrr), Pardee (rr), Pokegama (2)
(rr), Reserve (rr), Round (1) (rrr), Sand (1) (rrr), Sand (4) (rrr), Shell
(rrr), Sishebogema (rr), Tied Canoe (rr), Upper Turtle (rr), Wolf (r).

One of the few species of the genus that is exclusively confined to
the plankton. The curving of the coenobe and the double series of
ovoid cells at once separates it from all other species.

var. CAPITATUS G. M. Smith. PL 38, Figs. 15-16.
Trans. Wis. Acad. Sci., Arts, & Lett. ID1: 637, pi. 11, figs. 4-5. 1918.

Cells with nodular thickenings at the poles. (Euplanktont).
Cells 5-11 /* broad, 11-23 p long. 8-celled colonies 22-27 /-i broad,
20-35 /* long.

Center (rr).

154 WISCONSIN PHYTOPLANKTON

var. PLATYDISCA G. M. Smith. PL 39, Figs. 1-3.
Trans. Wis. Acad. Sci., Arts, & Lett. IS2: 451, pi. 30, figs. 101-105. 1916.

Colonies always flat, generally 8-celled. Cells oblong-elliptic and
arranged in a double series. Coenobia with small interstices between
the cells. (Facultative Planktont).

Cells 4.5-7.5 //, broad, 8-17 p, long. 8-celled coenobia 11-30 p. broad,
18-30 p. long.

Camp (rrr), Eagle (rr), Fowler (rr), George (rr), Horse (rrr), Kegonsa
(ss), Paddock (rr), Pine (1) (rr).

An alga that has been considered a normal variation of S. bijuga but
one which, as stated elsewhere (1. c.), seems more closely related to
8. arcuatus.

SCENEDESMUS ACUTiFORMis Schroder. PI. 39, Figs. 4-6.
Forschungsbr. a. d. Biol. Stat. zu Plon 5: 45, pi. 2, figs. 4*-4b. 1897.

Coenobia flat, of 2-4-8 (generally 4) cells arranged in a linear series.
Cells fusiform, with acute apices. Cell wall of interior cells with a
single ridge that extends from pole to pole on each side; wall of termi-
nal cell with 2-4 ridges. Poles of cells without spines or teeth. (Fac-
ultative Planktont).

Cells 5-8 n broad, 16-22 p. long. 4-celled colonies 16-22 //. broad,
20-25 p. long.

Mendota (rr), Rice (1) (rrr).

Only a single longitudinal ridge can be seen in a front view of the
cell but the number of ridges is readily ascertained in an end view of
cells. The presence of these ridges without accompanying spines or
teeth separates this from other species.

SCENEDESMUS ARMATUS (Chodat) G. M. Smith. PI. 39, Figs. 7-10.
Trans. Wis. Acad. ,Sci., Arts, & Lett. 18J: 460, pi. 29, figs. 90-93. 1916.

Coenobia of 2-^4-8 cells arranged in a linear or subalternating series.
Cells ovoid to oblong-ellipsoid; with rounded apices. Terminal cells
with a single long spine at each pole. Both sides of cells with a longi-
tudinal ridge that may extend from pole to pole but is generally indis-
tinct in the median portion of the cell. (Facultative Planktont).

Cells 4-7 p. broad, 7-16 p. long. 4-celled coenobia (without spines)
7-16 p. broad, 16-25 p. long. Spines 5-7 p, long.

Bear (2) (rr), Bear Trap (rrr), Bone (rr), Browns (rr), Carson (rr), Fish-
trap (rrr), Horseshoe (2) (rr), Lac Court Oreilles (rr), Little Butternut (rrr),
Little Crooked (rr), Loveless (rr), Lynx (rrr), Mendota (rrr), Pardee (rrr),
Pine Tree (rr), St. Croix (rrr), Silver (rr), Upper Turtle (rrr), Wolf (rr).

WISCONSIN PHYTOPLANKTON 155

var. major var. nov. PI. 39, fig. 11.

Cells up to 9 n broad and 25 /* long. Spines 15 //, long. (Facultative
Planktont ?).

Palmer (rr).

SCENEDESMUS BRASILIENSIS Bohlin. PI. 39, Figs. 12-14.
Bih. Kgl. Sv. Vet.-Ak. Handl. 23, Afd. 3, No. 7: 22, pi. 1, figs. 36-37. 1897.

Coenobia flat, of 2-4-8 (generally 4) cells arranged in a single linear
series. Cells cylindrical to ovoid-ellipsoid, with a single longitudinal
ridge extending from pole to pole on each side of the cell. Poles with
1-4 small teeth. (Facultative Planktont).

Cells 3-6 ^ broad, 11-24 //. long. 4-celled coenobia 11-24 //, broad,
12-25 /* long.

Bear (2) (r), Beaverdam (rrr), Chain (rrr), Clare (rrr), Deer (rrr), Jag
(rr), Lac du Flambeau (rrr), Lake of the Woods (rrr), Lindy (rr), Little
Doctor (rr), Old Taylors (rr), Pine (2) (rr), Rice (1) (rr), White Sand (rrr).

The species may be distinguished from S. denticulatus by the linear
ridges on the sides of the cells.

SCENEDESMUS HYSTRIX Lagerheim. PI. 39, Figs. 15-16.
o'fvers. Kgl. Vet.-Ak. Forh. 39, No. 2: 62, pi. 2, fig. 18. 1882.

Coenobia flat, of 2^4-8 cells joined in a single linear series. Cells
oblong-cylindrical, with blunt conical apices. Entire surface of cells
covered with minute spines. (Tychoplanktont).

Cells 3-5 p. broad, 8-18 /* long. 4-celled coenobia 8-18 /«, broad, 12-
25 p. long.

Rudolph (rrr).

SCENEDESMUS DENTICULATUS Lagerheim. PI. 39, Figs. 17-19.
Ofvers. Kgl. Vet.-Ak. Forh. 39, No. 2: 61, pi. 2, figs. 13-17. 1882.

Coenobia flat, generally four-celled. Cells ovoid to ovoid-ellipsoid,
arranged in a linear or subalternating series. Poles of cells without
ridges but with 1-4 short spines. (Facultative Planktont).

Cells 5-11 /x broad, 7-15 /*, long. 4-celled coenobia 7-15 ju, broad,
15-22 /i long.

Amicoy (rr), Bear (2) (rr), Browns (rr), Chain (rr), Deer (rrr), High (r),
Hillman (rr), Horse (rrr), Horseshoe (2) (rr), Lac du Flambeau (rrr), Lit-
tle Doctor (rrr), Silver (3) (rr), White Ash (rr), Wolf (rr).

156 WISCONSIN PHYTOPLANKTON

SCENEDESMUS LONGUS Meyen. PI. 39, Figs. 20-22.

Nova Acta Phys.-Med. Acad. Caes. Leop. Nat. Cur. 14: 774, pi. 43, fig. 28.
1829. G. M. Smith, Trans. Wis. Acad. Sci., Arts, & Lett. 182: 469, pi. 31, figs.
156-158. 1916.

Scenedesmus quadricauda var. setosus (Kirchner) Lagerheim, Ofvers. Kgl.
Sv. Vet.-Ak. Fort. 39, No. 2: 63. 1882.

Coenobe flat, of 2-4—8 (generally 4) cells arranged in a single linear
series. Cells ovoid to oblong-cylindrical, with rounded poles. Poles
of all cells with 1-2 spines. Cell wall destitute of spines except at the
poles. ( Tychoplanktont) .

Cells 4-5 p. broad, 8-11 ju. long. 4-celled coenobia 8-11 /x broad, 16-
20 p. long.

Rock (rr).

var. Naegelii (Brebisson) comb. nov. PI. 40, Figs. 1-2.

Scenedesmus Naegelii de Brebisson, Mem. de la soc. Imp. de Sc. Nat. de
Cherbourg 4: 158. 1856.

Scenedesmus caudatus Nageli non Corda, Gatt. einz. Algen 91, pi. 5, figs.
2c-2d. 1849.

Colonies flat, always eight-celled. Cells cylindrical, with rounded
poles. Terminal cells with spines at both poles, interior cells with
spines at one pole, rarely at both poles. (Facultative Planktont).

Cells 6.6-11 p broad, 18-33 /x long. 8-celled colonies 18-33 fj. broad,
50-85 /x long.

Blake (rr), Camp (rrr), Poor Farm (rrr), White Ash (rr).

This alga was described by de Brebisson from the drawings of
8. quadricauda by Nageli. In my monograph of Scenedesmus I in-
cluded it as a synonym of 8. longus (Trans. Wis. Acad. Sci., Arts, &
Lett. 182: 469. 1916) but am now convinced that it should be con-
sidered a distinct variety. The cells are much larger than the typical
form but unfortunately Nageli gives neither measurements for the cells
nor an indication of the scale of magnification of his drawings. The
measurements stated above are those of cells from Wisconsin lakes.
The peculiar arrangement of the spines that Nageli figures, where three
adjacent interior cells have spines on the same end and none on the
other with the reverse condition in the remaining interior cells, was
found to be a common but not a constant character since specimens were
found with spines at both poles of interior cells.

WISCONSIN PHYTOPLANKTON 157

SCENEDESMUS ABUNDANS (Kirchner) Chodat. PI. 39, Figs. 23-25.

Mater, p. la fl. crypt. Sulsse. 42: 77. 3913; G. M. Smith, Trans. Wis. Acad. Sci.,
Arts, & Lett. 182: 465, pi. 31, figs. 137-140. 1916.

Scenedesmus quadricauda var. abundans (Kirchner) Lagerheim, ofvers.
Kgl. Vet.-Ak. Forh. 39, No. 2: 64, pi. 2, fig. 20. 1882.

Coenobe flat, generally 4-celled. Cells ovoid to oblong-ellipsoid.
Terminal cells with 1-2 spines at poles and additional spines on outer
face between the poles. Interior cells with 1-2 spines at each pole.
(Facultative Planktont).

Cells 4-7 p. broad, 7-12 p. long. 4-celled coenobia 7-12 p. broad,
15-30 fi long. Spines 4-7.5 p, long.

Beaver (2) (rr), Cbchrane (rr), Diamond (rr), Grassy (rr), Horse (rr),
Long (1) (rrr), Nancy (rrr), Palmer (rr), Poor Farm (ss).

var. LONGICAUDA G. M. Smith. PI. 39, Figs. 26-27.
Trans. Wis. Acad. Sci., Arts, & Lett. 182: 467, pi. 30, figs. 121-125. 1916.

Cells smaller, ovoid. Spines much longer in proportion to the size
of the cells. (Facultative Planktont).

Cells 3-6 fjL broad, 7-9 p. long. 4-celled coenobia 7-9 p. broad, 10-15
p. long. Spines 6-10 p, long.

Camp (rr), Chain (rrr), Horse (rr), White Ash (rr).

var. BREVICAUDA G. M. Smith. PI. 40, Figs. 3-5.
Trans. Wis. Acad. Sci., Arts, & Lett. 182: 468, pi. 30, figs. 126-132. 1916.

Cells ovoid, smaller. Spines much shorter and never more than
three between the polar spines of terminal cells. (Facultative Plank-
tont).

Cells 2.5-5 ju, broad, 5-8 p. long. 4-celled coenobia 5-8 p. broad,
10-13 /x long. Spines 1.5-3.5 //. long.

Mendota (rr).

var. ASYMMETRICA (Schroder) G. M. Smith. PI. 40, Figs. 6-8.

Trans. Wis. Acad. Sci., Arts, & Lett. 182: 468, pi. 27, figs. 45-46. 1916.

Scenedesmus guadricauda var. asymmetrica Schroder, Forschungsbr. a. d.
Biol. Stat. zu Plon 5: 45, pi. 2, figs. 5a-5c. 1897.

Coenobia generally 4-celled, with oblong-ellipsoid cells. Poles of
terminal cells with a single spine. All cells of coenobe with a single
median spine perpendicular to the plane of the coenobe and at one
side of cell only. (Facultative Planktont).

Cells 2.5-4.5 p. broad, 12-15 //, long. 4-celled coenobia 12-15 p. bro
13-18 /i long. Spines 7-10 /u long.

Blue Gill (rr), Wild Goose (rrr).

WISCONSIN PEJTOPLANKTON

SCENEDESMUS QUADRicAUDA (Turpin) de Brebisson. PI. 40, Figs. 9-11.

M6m. de la Soc. Ac. de Falaise 1835: 66. 1835; G. S. West, Brit. Freshw. Algae
220, figs. 92i>-92F. 1904.

Coenobia flat, of 2-4-8-16 (generally 4) cells in a simple linear or
subalternating series. Cells cylindrical-ovoid, with rounded poles. Poles
of terminal cells with a single long straight or curved spine. Poles of
interior cells without spines. (Facultative Planktont).

Cells 3.5-6 p broad, 11-16 /*, long. 4-celled coenobia 11-16 p. broad,
12-23 p. long. Spines 10-12 ^ long.

Beaverdam (IT), Big Butternut (rrr), Blake (rr), Browns (rr), Camp (IT),
Chetek (rr), Clam (rr), Clear (rr), Eagle (rr), East (rrr), Fishtrap (rr),
Green (1) (rr), Hillman (rr), Horseshoe (2) (rr), Lac du Flambeau (rr),
Lindy (rr), Little Rice (2) (r), Lost (rr), Loveless (rr), Lower Nashotah
(rr), Lower Nemahbin (rr), Mary (rr), Meta (rr), Mud (1) (rr), Mud (2)
(rr), Muskallonge (r), Nancy (rr), Okauchee (rrr), Old Taylors (rr) Poke-
gama (I) (rr),Pope (rr), Poplar (rr), Poor Farm (sss), Rice (1) (rr), Round
(3) (rr), Sand (1) (rrr), Sand (4) (rr), Travis (ccc), White Ash (rr), Wild
Goose (rrr), Winnebago (rr).

The most ubiquitous species of the genus. The presence of spines
on the poles of the terminal cells only is the distinguishing feature of
the species. Cultural work has shown that it is possible to recognize
several distinct varieties of this species.

var. PARVUS G. M. Smith. PI. 40, Fig. 17.
Trans. Wis. Acad. Sci., Arts, & Lett. 182: 480, pi. 31, figs. 162-166. 1916.

Cells ovoid-cylindrical. Length of cells 2-2.5 times the breadth and
equal to the length of the spines. (Tychoplanktont).

Cells 3-4 /*- broad, 5.5-8 ^ long. 4-celled coenobia 5.5-8 /x broad,
12-15 n long. Spines 4.5-8 /* long.

Deer (rrr).

var. QUADRISPINA (Chodat) G. M. Smith. PI. 40, Figs. 15-16.
Trans. Wis. Acad. Sci., Arts, & Lett. 182: 479, pi. 31, figs. 167-171. 1916.

Cells broadly ovoid, about twice as long as broad. Spines short,
about as long as the diameter of the cell. (Tychoplanktont).

Cells 3.5-8 fi broad, 8.5-15 //. long. 4-celled coenobia 8.5-15 /i broad,
16-32 n long. Spines 2.5-5.5 /* long.

Mill (rrr), Pine (rr), Pokegama (1) (rrr), Round (1) (rr), Tied Canoe
(rrr).

WISCONSIN PHYTOPLANKTON 159

var. LONGISPINA (Chodat) G. M. Smith. PI. 40, Figs. 12-14.
Trans. Wis. Acad. Sci., Arts, & Lett. 182: 480, pi. 31, figs. 159-161. 1916.

Cells ovoid-cylindrical. Length of cells 2.5 times the breadth. (Fac-
ultative Planktont).

Cells 3.5-5 p. broad, 8-11 p. long. 4-celled coenobia 8-11 p. broad,
12-20 p, long. Spines 7.5-10 p. long.

Horse (rr), Lost (rr), Mendota (sss), Palmer (r).

var. WESTII G. M. Smith. PI. 41, Figs. 3-7.
Trans. Wis. Acad. Sci., Arts, & Lett. 182: 480, pi 32, figs. 177-180. 1916.

Cells 4.5-8 p. broad, 16-22 p long. 4-celled coenobia 16-22 p. broad,
25-35 p. long. Spines 12-16 p long. (Facultative Planktont).

Bear Trap (rrr), Blake (rr), Camp (rr), Cochrane (rr), Crawling Stone
(rr), Grassy (rr), Horse (rrr), Lac Court Oreilles (rr), Loon (rrr), Meta
(rr),, Silver (2) (rr).

var. MAXIMUS W. & G. S. West. PI. 41, Figs. 1-2.
Trans. Linn. Soc. 2 Ser. Bot. 5: 83, pi. 5, figs. 9-10. 1895.

Cells much larger and spines proportionally longer. (Facultative
Planktont).

Cells 9-11.5 p, broad, 27-36 p. long. 4-celled coenobia 27-36 p. broad,
35-40 p. long. Spines 20-30 p. long.

Eagle (rr), Nicaboyne (rr), Pine Tree (rr), Poor Farm (rr), Tenderfoot
(rrr), Travis (r).

SCENEDESMUS OPOLiENSis P. Eichter. PL 41, Figs. 8-11.
Zeits. f. angw. Mikr. 1: 7, figs. A-E. 1896.

Coenobia flat, of 2-4-8 (generally 4) cells in a single linear series.
Interior cells naviculoid, outer margin of terminal cells straight or
slightly convex. Cells in lateral contact in median third only. Termi-
nal cells with a long spine at each pole ; interior cells with or without
long or short spines. Polar spines greatly reduced at times. (Faculta-
tive Planktont).

Cells 5-8 p. broad, 12-28 p. long. 4-celled coenobia 12-28 p. broad,
15-30 p. long. Spines 5-28 p. long.

Palmer (rr).

The navicular shape of the cells, their lateral contact in the median
third only, together with the beak-like instead of rounded apex sepa-
rates this species from S. quadricauda.

160 WISCONSIN PHYTOPLANKTON

Sub-family COELASTREAE.

Coenobia forming a sphere with the cells radially arranged in a single
layer around a common center. The number of cells in a coenoba al-
ways a multiple of two. Cells spherical, polygonal, or elongate cylindri-
cal.

KEY TO THE GENERA.

Cells spherical, polygonal, or flattened; length never more than twice the
breadth.

Cells without spines on the outer face COELASTBUM

Cells with spines on outer face SOBASTBUM

Cells 3-7 times as long as broad ACTINASTBUM

COELASTRUM Nageli 1849.

Coenobe a hollow sphere of 2-4-8-16-32-64-128 cells. Cells spheri-
cal, ovoid, or pyramidal ; compressed or with large intercellular spaces ;
enclosed in a very delicate gelatinous sheath. Daughter coenobia some-
times remaining joined in multiple coenobia by the remains of the old
mother cell wall.

Reproduction by autocolony formation in any cell of the coenobe.
Liberation of young coenobia by a rupture of old mother cell wall.

KEY TO THE SPECIES.
Cells spherical.

Processes uniting the cells long C. RETICULATUM

Processes uniting the cells short.

External face of cells without projections C. MICBOPOBUM

External face of cells with short truncate projections. . .C. CAMBRICUM
Cells truncate cones C. PBOBOSCIDETTM

COELASTRUM MICROPORUM Nageli. PL 41, Figs. 12-13; PL 42, Fig. 1.
in Braun, Alg. unicell. 70. 1855; Senn, Bot. Ztg. 57: 53, pi. 2, figs. 11-17. 1899.

Coenobia spherical to ovoid ; with 8-16-32-64 cells. Cells spherical,
enclosed by a delicate gelatinous sheath and connected to one another
by short, stout, gelatinous processes. Intercellular interstices smaller
than the diameter of the cells. (Facultative Planktont).

Diam. cells (without sheath) 3-20 /*; (with sheath) 4-23 p.. Diam.
coenobia 20-90 /A.

Balsam (rrr), Bear (1) (rr), Bear (2) (rr), Bear Trap (rrr), Big Butter-
nut (rrr), Blake (rrr), Bone (rrr), Boulder (rrr), Browns (rr), Center
(rr), Chetac (rr), Cochrane (rr), Deer (rrr), East (rrr), Elizabeth (rrh
Fishtrap (rrr), Granite (rr), Hill (rr), Hillman (rrr), Horseshoe (2) (rrr),

WISCONSIN PHYTOPLANKTON

Inland (rr), Lac du Flambeau (sss), Little Bass (2) (rr), Little Butternut
(rr), Little Crooked (rrr), Little Doctor (rr), Loveless (rrr), Lower Na»h-
otah (rrr), Lower Turtle (rr), Mary (rr), Mendota (sss), Mill (rrr), Mud (.2)
(rr), Nancy (rrr), Oconomowoc (rr), Otter (rrr), Pewaukee (rrr), Pine Tree
(rrr), Pokegama (1) (rr), Pokegama (2) (rr), Poor Farm (rrr), Pope (rrr),
Prairie (rrr), Round (1) (rrr), Sand (1) (rr), Sand (4) (rr), Shell (rrr).
Silver (1) (rr), South Turtle (rr), Squirrel (rr), Tenderfoot (rr), Tied Canoe
(rrr), Travis (rrr), Vermilion (rr), White Ash (rrr), White Sand (rrr),
Wolf (rrr).

A species that is found in all types of lakes.

COELASTRUM CAMBRicuM Archer. PL 42, Figs. 2-3.

Quart. Jour. Micr. Sci. N. S. 8: 65. 1868; W. West, Jour, of Bot. 31: 99, pi.
333, fig. 14. 1893.

Coenobia spherical, of 8-16-32-64-128 (generally 32) cells. Cells
spherical, with a single truncate projection on the outer face. Each,
cell connected to adjacent ones by short, somewhat flattened, gelatinou*
projections. Small circular or triangular interstices between the cells.
(Facultative Planktont).

Diam. cells (with sheath) 6-21 /*, (without sheath) 5-18 /A. Diam.
eoenobia 20-100 /*.

Balsam (rrr), Bear (2) (rr), Beaverdam (rr), Birch Island (rrr), Blue
Gill (rrr), Catfish (rr), Cochrane (rrr), Cranberry (rr), East (rr), Found
(rr), Hillman (rrr), Jag (rr), Little Bass (2) (r), Mercer (rr), Middle Mc-
Kenzie (rrr), Minocqua (rr), Nancy (rrr), Nicaboyne (rr), Old Taylors (rrr),
Owen (rrr), Pine (1) (rr), Pine Tree (rr), Pokegama (1) (rr), Prairie (rr),
Rudolph (rrr), St. Croix (rr), Silver (1) (rr), Streitor (rr), Travis (r),
Wild Goose (rrr).

COELASTRUM RECTICULATUM (Dangeard) Senn. PL 42, Figs. 4-6.
Bot.^Ztg. 57: 66, pi. 2, figs. 1-10. 1899.

Coenobia spherical, of 8-16-32 cells ; generally held in multiple eoe-
nobia by the remains of old mother cell walls. Cells spherical, enclosed
by a narrow gelatinous sheath and connected to adjacent cells by 6-9
long, slender, tough, gelatinous processes. (Facultative Planktont).

Diam. cells (with sheath) 6-24 /x. Diam. eoenobia 10-65 //..

Bear Trap (rrr), Bear (3) (rr), Beaverdam (rrr), Big McKenzie (rrr).
Birch (2) (rr), Blake (rrr), Browns (ss), Camp (rr), Fish (rr), High (rrr),
Island (rr), Lac Court Oreilles (rr), Little Bass (2) (rr), Mary (rr), Mendota
(rr), Mud (1) (rr), Mudhen (rr), Nancy (rr), North Twin (rrr), Palmer (rr).

The long processes connecting the cells distinguish this species from,
all others. Solitary eoenobia are rarely met with since the long proc-
esses hinder the escape of young eoenobia.

11

162 WISCONSIN PHYTOPLANETON

COELASTRUM PROBOSCIDEUM Bohlin. PL 42, Figs. 7-8; PI. 43, Figs. 1-2.
Bih. t. Kgl. Sv. Vet.-Ak. Handl. 23, Afd. 3, No. 7: 33, pi. 2, figs. 19-22. 1897.

Coenobia pyramidal or cubical, rarely polygonal; of 4r-8-16-32 (gen-
erally 4 or 8) cells; frequently joined in compound coenobia of irregu-
lar shape. Cells truncate cones, at times with concave sides ; with base
of cone towards the center of coenobe. Interstices between cells large,
polygonal. Chloroplast single, parietal, with one pyrenoid. (Faculta-
tive Planktont) .

Diam. cells 6.5-17 /*; diam. 4-celled coenobia 12-35 /*; compound
coenobia up to 350 ^ in diam.

Bear Trap (rrr), Cochrane (rr), Durchmans (rrr), Pine Tree (aa), Round
(rrr).

The appearance of this alga as the dominant organism of the plankton
of Pine Tree lake is of particular interest since Coelastrum species have
not been reported as occurring in abundance by any student of the
phytoplankton. Compound coenobia were very common and it was not
at all unusual to find 50-80 four- or eight-celled coenobia joined in one
irregular mass. The cells of four-celled coenobia are tetrahedrically
arranged in the manner that G. S. West has described them for Coelas-
trum compositum (Jour. Linn. Soc. Bot. 38: 136, pi. 5, figs. 8-9. 1907)
and I believe that C. compositum should be considered a synonym of
C. proboscideum. The cellular arrangment of eight-celled coenobia is
exactly as Bohlin and Senn describe. In the sixteen-celled coenobia,
which are of very rare occurrence, the cells form a hollow sphere so that
the general appearance of the colony resembles the other species of the
genus. This difference in cell number is of minor significance, the
number of cells in a colony being dependent upon the vegetative vigor
of the mother cell at the time colony formation takes place.

SORASTRUM Kiitzing. 1845.

Cells pyriform, semilunar, or reniform; united to form spherical
colonies of 8-16-32-64-128 cells. Center of colony a polyhedral body
from which gelatinous strands radiate to each cell. Distal side of cells
with 1, 2, or 4 spines. Chloroplast diffuse, with one pyrenoid.

Reproduction unknown ; presumably by autocolonies as in Coelastrum,
possibly by zoospores as in Pediastrum.

WISCONSIN PHTTOPLANKTON 163

KEY TO THE SPECIES.

Spines on outer face of cells short (4-8 M) S. SPINTJLOSUM

Spines on outer face of cells long (10-15 /*) S. AMEBICANUM

SORASTRUM SPINULOSUM Nageli. PI. 44, Figs. 4-5.

Gatt. einz. Algen 99, pi. 5, figs. Da-Dd. 1849; G. S. West, Brit. Freshw. Algae
215, figs. 89A-89B. 1904.

Coenobe of 4^8-16-32 cells. Cells broadly renii'orm to cuneate, with
four short horns at the corners of the outer face. Stipe leading to
sphere at center of colony short. Chloroplast single, generally filling
the entire cell; pyrenoid single. (Tychoplanktont).

Cells 8-20 ^ broad, 6-18 /*, long, 5-8 p, thick. Horns of adult cells
4-8 fji long.

Hillman (rrr), Horse (rrr).

SORASTRUM AMERICANUM (Bohlin) Schmidle. PI. 44, Fig. 1.

Engl. Jahrb. 27: 230. 1900: Lemmermann, Arch. f. Hydrob. u. Planktonkde.
5: 310, fig. 5. 1910.

Selenosphaerium americanum Bohlin, Bin. t. Kgl. Sv. Vet.-Ak. Handl. 23,
Afd. 3, No. 7: 40, pi. 2, figs. 38-41. 1897.

Coenobia spherical, solitary, of 16-32-64-128 (generally 16 or 32)
cells. Cells cardiate to pyramidate, somewhat flattened, with the apex
towards the center of the coenobe and ending in a broad gelatinous
stalk as long as the cell. Stalk cylindrical, 5-6 faceted at the base;
•with the facets in contact with those of other stalks and forming a hol-
low sphere. Outer face of cells emarginate, with a single long spine at
each of the four corners. (Facultative Planktont).

Cells 7-20 ^ broad, 5-20 p. long (without stalk), 4-8 /* thick. Spines
of adult cells 10-15 /* long.

Devils (1) (rr), Devils (2) (rrr), Nancy (rrr), Travis (rr).

The longer spines and stalk, together with the more prominent central
sphere, separates this species from the foregoing.

var. UNDULATUM G. M. Smith. PI. 44, Figs. 2-3.
Trans. Wis. Acad. Sci., Arts, & Lett. 191 : 640, pi. 13, fig. 1. 1918.

Sides of facets at base of stipe undulate. Dimensions as in the typi-
cal form. (Facultative Planktont).

Beaverdam (rrr).

164 WISCONSIN PHYTOPLANKTON

ACTINASTRUM Lagerheim 1882.

Coenobia free-floating, of 4-8-16 (generally 8), ovoid, cylindrical,
elub-shaped, or drum stick shaped cells radiating from, a common cen-
ter. Coenobia sometimes united to form multiple coenobia of irregular
shape. Each cell with a single, laminate, parietal chloroplast; with
or without pyrenoids.

Reproduction by longitudinal and transverse division of the contents
of any cell, the young autocolony being liberated by a rupture of the
mother cell wall.

KEY TO THE SPECIES.

Center of cell twice as broad as poles A. HANTZSOHI

Center of cells about the same width as the poles A, GRACILLIMUM

ACTINASTRUM GRACILUMUM G. M. Smith. PI. 43, Figs. 3-5.
Bull. Torr. Bot. Cl. 43: 480, pi. 26, fig. 23. 1916.

Coenobia of 4 or 8 cells radiating from a common center. Cells elon-
gate-cylindrical, tapering but slightly to a truncate end, 7-10 times as
long as broad. Chloroplast single, parietal, laminate, with or without
a pyrenoid. (Euplanktont).

Cells 1.75-3 p. broad, 14-21 ju, long; colonies 30-45 p. in diarn.

Horse (rr), Kegonsa (rrr), Mendota (rr).

The species differs from the following in the very slight dilation of
the median portion of the cell and the greater proportional length.

ACTINASTRUM HANTZSCHI Lagerheim. PI. 43, Figs. 6-7.
Ofvers. Kgl. Vet.-Ak. Forh. 39, No. 2: 70, pi. 3, figs. 25-26. 1882.

Coenobia of 4 or 8 cells radiating from a common center. Coenobia
sometimes united to form multiple coenobia. Cells 3-6 times as long
as broad, with truncate poles, ovoid-cylindrical. Diameter of middle
of cells twice that of poles. Chloroplast single, parietal, laminate ; with
one pyrenoid. (Euplanktont).

Cells 3-6 p broad, 10-26 ^ long ; coenobia up to 50 /* in diam ; com-
pound coenobia up to 200 /x. in diam.

Chetek (rr), Kegonsa (r), Lower Turtle (rrr), Mendota (rr), Prairie (rr),
Upper Turtle (rr), Waubesa (rrr).

Multiple coenobia are of rare occurrence and have only been found
in the plankton of Chetek lake. This may be due to the fact that such
colonies readily fragment into the individual coenobia and the handling
incident to the collection of samples is sufficient to break up multiple
coenobia.

WISCONSIN PHYTOPLANETON 165

TQT. ELONGATUM G. M. Smith. PI. 43, Fig. 8.

Trans. Wis. Acad. Sci., Arts, & Lett. 19' : 636, pi. 12, fig. 3. 1918.

Colonies of 4 or 8 cells. Cells cylindrical, tapering but little towards
the poles. ( Euplanktont) .

Cells 4-5 n broad, 30-35 /x long.

Bear (3) (rr).

The cells of this variety are much longer than those of the typical
form.

Family HYDRODICTYACEAE.

Cells cylindrical, or flattened and hexagonal to trapezoidal with one,
two, or four projections. Coenobia of definite shape ; cylindrical with
a large number of cells; or disciform with 2-4-8-16-32-64-128 cells.
Cells incapable of division after their formation. Chloroplast single,
parietal, laminate to reticulate, frequently filling the entire mature
cell ; with one to many pyrenoids.

Asexual reproduction by the division of contents of any cell to form
zoospores that swarm within old cell wall or within a gelatinous vesicle
extruded from the cell. Zoospores becoming apposed in the shape of
the adult cell when they come to rest.

Sexual reproduction by isogamous zoogametes which fuse in pairs to
form angular resting cells which form colonies on their germination.

KEY TO THE GENERA.

Coenobe a hollow cylindrical tube with rounded ends HYDRODICTYON

Coenobe a flattened disc one cell in thickness.

Number of cells in coenobe always 2 EUASTBOPSIS

Number of cells in coenobe 4-8-16-32-64-128, very

rarely 2 PEDIASTBTTM

HYDRODICTYON Both 1800.

Cells macroscopic, oblong-cylindrical with rounded ends; united to
form a free-floating, reticulate, saccate coenobium. Meshes of nets
3-12 (generally 5-6) sided. Cells coenocytic; chloroplast parietal,
reticulate at first, later diffuse; pyrenoids single in very young cells,
several hundred in mature cells.

Asexual reproduction by the division of cell contents into very many
biciliate zoospores which swarm about in and become arranged as in
the mature coenobe within the old mother cell wall. Liberation of the
young coenobe by a gradual gelatinization of the mother cell wall.

Sexual reproduction by zoogametes which are similar in structure to

166 WISCONSIN PHTTOPLANKTON

zoospores but smaller, the zoogametes fusing in pairs to form a spheri-
cal zygote after their liberation through a pore in the cell wall. Zygote
germinating, after a short period of rest, into 2-5 large uni- or biciliate
zoospores that form irregular polyhedral cells on coming to rest. Poly-
eders ultimately germinating into 200-300 zoospores that are liberated
in a vesicle and form a net as in asexual reproduction.

HYDRODICTYON RETICULATUM (L) Lagerheim. PI. 44, Fig. 6; PI. 45,

Fig. 1.

Ofvers. Kgl. Vet.-Ak. Forh. 40, No. 2: 71. 1883; G. S. West, Brit. Freshw. Algae
208, figs. 84A-84F. 1904

Cells elongate cylindrical, forming a definite closed net. (Tycho-
pJanktont).

Cells 5-250 p broad, up to 1.5 cm. long. Coenobia up to 30 cm. long.

Little Bass (2) (rr), Mendota (rr), Monona (sss).

An alga that is in no sense a plankton organism but one which some-
times grows in abundance in shallow, well protected bays and so may,
at times, be found free-floating in large patches a considerable distance
from the shore.

PEDIASTRUM Meyen 1829.

Coenobia disciform to stellate, free-floating, of 2-4-8-16-32-64-128
cells arranged in a layer one cell in thickness. Coenobe entire, perfor-
ate, or clathrate. Marginal cells polygonal, with one, two, or four proc-
esses that sometimes terminate in a tuft of long hyaline setae. Interior
cells polygonal, without processes. Cell wall smooth, granulate, or
covered with a meshwork of fine ridges; without a gelatinous sheath.
Chloroplasts parietal and disciform at first, later filling the entire cell ;
with 1-4 pyrenoids. Cells coenocytic.

Asexual reproduction by the division of contents of any cell into
2-4-8-16-32-64-128 biciliate zoospores that are extruded in a gelatinous
vesicle and, after a short period of swarming, on becoming quiescent
appose themselves in the same position as the mature cells of the
coenobe.

A fusion of biciliate zoogametes into polyhedral resting cells has been
observed. On germination these zygospores form 8-16-32 zoospores
that behave as in asexual reproduction.

WISCONSIN PHYTOPLANKTON

KEY TO THE SPECIES.

Outer face of marginal cells without projections.

Wall smooth p. INTEGEUM

Wall reticulate p. ABANEOSUM

Outer face of marginal cells with 1, 2, or 4 projections.
Marginal cells with more than one projection.

Cells on margin with four projections and a deep linear incision. .P. TETBAS
Cells on margin with two projections.
Coenobe entire.
Cell wall smooth or punctate.

Projections side by side in front view of cell P. BORYAJTOM

Projections above one another in front view P. KAWRAISKYI

Cell wall reticulate.

Wall covered with coarse reticulations P. ABANEOSTTM

Wall covered with fine reticulations P. ScuipTATtrM

Coenobe perforate.

Ends of projections truncate P. DUPLEX

Ends of projections incised P. BESADIATUM

Marginal cells with one projection P. SIMPLEX

PEDIASTRUM SIMPLEX var. DUODENARIUM (Bailey) Rabenhorst. PL 45,

Figs. 2-6.

Fl. Eur. Algarum 3: 72. 1868.

Monactinus duodenarius Bailey, Smithsonian cont. to knowl. 7, Art. 3: 14,
pi. 1, fig. 37. 1855.

Monactinus octonarius Bailey, ibid. p. 14, pi. 1, fig. 36. 1855.

Pediastrum simplex var. clathratum (Schroter) G. S. West, Jour. Linn. Soc.
Bot. 38: 134. 1907.

Coenobia circular to oval, of 4-8-16-32-64-128 (generally 8-16-32)
cells. Inner face of marginal cells concave, outer face produced into
a single, delicately tapering, concave process frequently furnished with
a tuft of delicate hyaline setae. Interior cells as those of the periphery
but with shorter processes. Interstices between cells large. Cell wall
smooth or finely punctate. (Facultative Planktont).

Cells 10-24 n broad, 20-45 p. long.

Balsam (rr), Bear (1) (r), Bear Trap (rrr), Blake (r), Camp (rr), Green
(1) (rrr), High (rr), Hillman (rrr), Kegonsa (rr), Little Bass (rr), Little
Butternut (r), Little Crooked (rrr), Lost (rr), Loveless (rrr), Mary (rr),
Monona (r), Mud (2) (rr), Palmer (rrr), Pokegama (1) (sss), Rice (1) (r),
St. Croix (rr), Silver (1) (rr), Spirit (rr), Upper Turtle (r), Vermilion (cc),
Wapagossett (r), White Ash (rr), Winnebago (rr), Wolf (rrr).

This alga is one that has been given a number of names by various in-
vestigators, but for the reasons stated elsewhere (Trans. Wis. Acad. Sci.,
Arts, & Lett. 191: 642. 1918) I consider the one given above the proper
name.

168 WISCONSIN PHJTOPLANETON

PEDIASTRUM INTEGRUM Nageli. PI. 45, Fig. 7.

Gatt. einz. Algen 97, pi. 5, figs. B4a-B4r. 1849.

Coenobia 8-16-32-64-celled, circular or oval, without perforations.
Interior cells polygonal ; marginal cells 5-6 sided, at times with rudi-
ments of two projections that are sometimes reduced to a single wart,
but generally without projections. Cell wall smooth or punctate.
( Tychoplanktont) .

Diam. cells 15-30 /i.

Soft (rrr).

var. PRIVA Printz. PI. 45, Figs. 8-10.

Skr. Vidensk. i Kristiana Mat.-Naturv. Kl. 19131: No. 6: 73, pi. 5, fig. 147.
1914.

Coenobia generally 8-celled. Marginal cells trapezoidal, without in-
cisions or processes. Interior cells polygonal, without incisions. Cell
wall smooth. (Facultative Planktont).

Diam. cells 8-10 p. Diam. 8-celled coenobia 15-25 /*.

Palmer (rr).

The general shape of the cells is like that of P. tetras but since there
are no incisions in the cells they cannot be placed among the varieties
of P. tetras.

PEDIASTRUM ARANEOSUM Eaciborski. PI. 45, Fig. 11.
Mem. Acad. Imp. Sci. Cracow 20: 84. 1890.

Coenobia circular to oval, without perforations, of 8-16-32-64-128
cells. Interior cells in contact with 4—6 other cells, straight sided. In-
ner half of marginal cells similar to interior cells, outer half without
processes but with a deep emargination. Surface of cell covered with
a coarse reticulum of ridges. (Facultative Planktont).

Diam. cells 15-32 /*.

Birch Island (rr), Blue Gill (rrr), Boulder (rrr), Carson (rrr), Deer (rrr),
Devils (1) (rrr), Diamond (rrr), Dutchmans (rr), Horseshoe (1) (rr), Lake
of the Woods (rrr), Lindy (rr), Loon (rrr), Nicaboyne (rr), Nancy (r), Pine
Tree (rr), Pokegama (1) (rrr), Poor Farm (rrr), Sand (2) (rr), Wild
Goose (rr).

var. RUGULOSUM (G. S. West) G. M. Smith. PI. 45, Figs. 12-13.
Bull. Torr. Bot. Cl. 43: 476, pi. 25, fig. 14. 1916.

Sides of cells undulate where they are in contact with one another.
(Facultative Planktont).
Meta (r).

WISCONSIN PHYTOPLANKTON 169

PEDIASTRUM SCULPTATUM G. M. Smith. PI. 46, Fig. 1.
Bull. Torr. Bot. Cl. 43: 475, pi, 25, fig. 13. 1916.

Coenobia oval to circular, of 8-16-32 cells. Interior cells with 4-6
straight sides, with a few interstices between the cells. Marginal cells
bilobed, with the lobes produced into two short divergent or parallel
processes. Cell wall covered with a network of very fine ridges. (Fac-
ultative Planktont).

Diam. cells 10-15 /*. Diam. coenobia 80-150 /*.

South Turtle (rr).

PEDIASTRUM BORYANUM (Turpin) Meneghini. PI. 46, Figs. 2-7.

Linnaea 14: 210. 1840; G. S. West, Brit. Freshw. Algae 211, figs. 85F-85H.
1904.

Coenobia circular to ovoid, of 4-8-16-32-64-128-256 (generally 8-
16-32) cells that are normally compactly arranged in concentric rings.
Interior cells 4-6 sided, with straight sides. Inner half of marginal
cells similar to interior cells ; outer half produced into two short obtuse
processes ending in short spines, slightly to deeply emarginate between
the processes. Projections on outer face and their spines sometimes
greatly reduced. Wall smooth or granulate. (Facultative Planktont).

Diam. cells 7.5-30 /*. Diam. 16-celled coenobia 40-100 /*.

Balsam (rrr), Bear (1) (rrr), Bear (2) (rrr), Bear (3) (ss), Bear Trap
(rr), Beasley (rr), Beaver (rr), Beaverdam (ss), Big Butternut (rr), Birch
Island (rr), Blake (rr), Bloom (r), Boulder (rrr), Browns (rr), Camp (r),
Carroll (sss), Carson (rrr), Catherine (rr), Center (ss), Chetac (rr), Chetek
(rrr), Clear Crooked (rr), Cochrane (rrr), Crawling Stone (rr), Deer (r), Des
Moines (rr), Devils (1) (rr), Eagle (sss), East (rrr), Elizabeth (rrr), Fence
(rrr), Fishtrap (rr), Found (rr), Fowler (rrr), Geneva (rr), Granite (rr),
Grassy (rr), Green (2) (rrr), Grindstone (rr), Half Moon (rrr), Harris (rr),
High (rr), Hillman (rr), Hooker (rr), Horse (rrr), Horseshoe (1) (ss),
Kawaguesaga (r), Kegonsa (sss), Kitten (rr), Lac la Belle (rr), Lac Court
Oreilles (rr), Lac du Flambeau (r), Lindy (rr), Little Bass (2) (r), Little
Bear (sss), Little Butternut (rrr), Little Crooked (rr), Little Rice (2) (rr),
Little Wood (rrr), Long (2) (rr), Long (3) (rrr), Loveless (r), Lower Nash-
otah (rrr), Lower Nemahbin (rr), Lower Turtle (rr), Marl (rr), Mary (ss),
Mendota (ss), Monona (ss), Mud (1) (r), Mud (2) (r), Mudhen (rr), Muskal-
longe (rr), Nagawicka (rr), Nancy (sss), Nicaboyne (rrr), Oconomowoc (rr),
Old Taylors (rr), Owen (r), Paddock (rrr), Pewaukee (rr), Pine (2) (rrr),
Pokegama (1) (sss), Pokegama (2) (r), Pokegama (3) (rr), Poor Farm (rr),
Poplar (rr), Prairie (rrr), Rainbow (rr), Reserve (rrr), Rice (1) (rr), Round
(1) (sss), Round (2) (rr), St. Croix (rr), Sand (1) (rrr), Sand (3) (rrr),
Sand (4) (sss), Silver (2) (r), Spirit (rr), Star (rr), Streitor (rr), Taylor
(r), Tenderfoot (rrr), Tied Canoe (rrr), Turtle [North and South] (rr), Up-

170 WISCONSIN PHTTOPLANKTON

per Turtle (r), Vermilion (rr), Waubesa (r), White Ash (sss), Whitefish (rr),
White Sand (rr), Wildcat (rrr), Winnebago (r), Wolf (s).

A species that is almost universally present and one which varies
greatly in the character of the marginal cells.

var. UNDULATUM Wille. PI. 46, Fig. 8.
Ofvers. Kgl. Vet.-Ak. Forh. 36, No. 5: 28. 1879.

Sides of cells in contact with other cells undulate instead of straight.
(Tychoplanktont) .
Winnebago (rr).

var. LONGICORNE Raciborski. PI. 46, Fig. 9.

Akad. Umiej. w. Krakowie 20: 13. 1889; Printz, Skr. Vidensk. i Kristiana
Mat.-Naturv. Kl. 1913, No. 6: 74, pi. 5, fig. 149. 1914.

Horns at the ends of processes much longer than typical form, some-
times swollen at apex. Cell wall smooth or granulate.
Diam. cells up to 40 p. Horns 12-30 ju, long.
Bone (rrr).

Raciborski recognizes the forms glabrum and granulatum but,, judg-
ing by the variation in the nature of the wall in the typical form, these
forms should not be recognized.

PEDIASTEUM KAWRAISKYI Schmidle. PI. 46, Figs. 10-13.

Arb. d. Botan. Gartens zu Tiflis 2: 269. 1897; Nitardy, Beih. z. Bot. Cent. 322:
164, pi. 5, fig. 5. 1914.

Coenobia of 16-32-64 cells that are compactly arranged. Interior
cells 4-6 sided, sides straight. Inner half of marginal cells as interior
cells, outer half with two short projections that lie one above the other
when the coenobe is seen in surface view. Cell wall smooth. (Eu-
planktont) .

Diam. cells 9-22 /*. Diam. 32-celled coenobia 60-100 /*.

Big Bass (r), Palmer (rr), Tenderfoot (rrr), Winnebago (r).

The cell shape is quite similar to P. Boryanum but the peculiar posi-
tion of the processes on the marginal cells at once distinguishes this
species from all others. Some investigators are inclined to the view
that P. Kawraiskyi is but a passing condition of P. Boryanum that is
found for one generation only. I have grown P. Boryanum in pure
cultures for several years and have never seen a single coenobe with the
projections of marginal cells lying one above the other, and so feel con-
fident that P. Kawraiskyi is not a temporary growth condition of
P. Boryanum.

WISCONSIN PHYTOPLANKTON

PEDIASTRUM DUPLEX Meyen. PL 46, Figs. 14-16.

Nova Acta Phys. Med. Ac. Caes. Leop.-Carol. Nat. Cur. 14*: 772, pi. 43, figs.
6-20. 1829.

Coenobia of 8-16-32-64^128 (generally 16-32) cells, with small lens-
shaped perforations between the cells. Interior cells more or less rec-
tangular, not in contact with one another in the central portion of the
side walls. Inner half of marginal cells similar to interior cells, outer
half prolonged into two short truncate processes. Cell wall smooth.
(Facultative Planktont).

Diam. cells 11-21 p..

Balsam (rrr), Bear (2) (r), Birch Island (rr), Browns (rr), Catherine (rr),
Center (r), Clam (rrr), Cochrane (rr), Crawling Stone (r), Deer (rr), Des
Moines (rrr), Diamond (rrr), Eagle (r), Fishtrap (rr), Found (rr), Fowler
(rr), Helen (1) (rr), High (rr), Kawaguesaga (rr), Kegonsa (r), Kitten (r),
Lac la Belle (r), Lindy (rr), Little Bass (2) (rr), Little Bear (r), Little
Crooked (r), Little Rice (2) (rr), Long (3) (rrr), Lost (rr), Mendota (sss),
Mercer (rr), Meronk (rrr), Monona (c), Nagawicka (rr), Nancy (sss), Nica-
boyne (rrr), North Twin (rr), Oconomowoc (rr), Okauchee (rr), Pardee (rr),
Pokegama (1) (ss), Pokegama (2) (rr), Poor Farm (r), Poplar (rrr), Round
(1) (r), Round (2) (rr), Sand (4) (sss), Sishebogema (rr), Soft (r), South
Turtle (sss), Taylor (rr), Tenderfoot (r), Tied Canoe (rrr), Upper Nemahbin
(rr), Waubesa (ccc), White Sand (rrr), Wildcat (sss), Wild Goose (rrr),
Winnebago (ss),Wolf (sss).

In many cases the marginal cells of this species and the varieties
clathratum, reticulatum and gracillimum have a tuft of long hyaline
setae at the apex of the projections. Their function is to give buoyancy
to the coenobe when living under pelagic conditions. Petersen (Bot.
Tids. 31: 161-176. 1911) has been able to demonstrate their presence
in other species by means of stains.

var. CLATHRATUM (A. Braun) Lagerheim. PI. 47, Figs. 1-3.
Ofvers. Kgl. Vet.-Ak. Forh. 89, No. 2: 56. 1882.

Cells more deeply emarginate and perforations of disc larger. (Fac-
ultative Planktont).
Diam. cells 12-22 p.

Balsam (rr), Bear (3) (rr), Bear Trap (rr), Beaverdam (sss), Big Butter-
nut (rr), Blake (r), Bloom (rr), Camp (ss), Catfish (rr), Catherine (rr),
Chetek (s), Cranberry (rr), East (rrr), Fish (s), Horseshoe (1) (rr), Horse-
shoe (2) (rr), Lac du Flambeau (rrr), Lac la Belle (r), Little Bass (2) (ss),
Little Butternut (r), Little Wood (rrr), Long (1) (rrr), Loveless (sss),
Lower Turtle (r), Mary (r), Mendota (r), Middle McKenzie (s), Mud (2) (rr),
Mud (3) (sss), Nancy (r), Okauchee (rrr), Old Taylors (rrr), Fokegama (1)
(r),Rice (1) (es), Round (2) (rr),>Sand (3) (rr), Sand (4) (r), Spirit (sss),
Upper Turtle (sss), Wapagossett (rr), White Ash (r).

172 WISCONSIN PHTTOPLANKTON

var. RETICULATUM Lagerheim. PI. 47, Figs. 4-7.
Ofvers. Kgl. Vet.-Ak. Forh. 89, No. 2: 56, pi. 2, fig. 1. 1882.

Perforations of coenobe very large, oval. Interior cells sub-cruciate
to H-shaped. Sides of projections of marginal cells parallel, projec-
tions generally terminating in a tuft of delicate long hyaline setae.
(Euplanktont ?).

Cells 10-20 fi broad, 15-40 /* long.

Big (rr), Camp (s), Center (s), Chetek (s), Crab (rr), Hill (rr), Hooker
(rr), Horse (sss), Island (sss), Kawaguesaga (rr), Little Bear (rr), Little
Rice (1) (rr), Lost Bass (r), Loveless (r), Nancy (r), Paddock (rr), Palmer
(r), Pardee (r), Pine (2) (rrr), Pokegama (1) (r), Pokegama (3) (ss),
Prairie (ss), Reserve (rr), Rice (r), St. Croix (sss), Sishebogema (r), South
Turtle (rr), Tenderfoot (rr), Waubesa (rr), Whitefish (rr), Winnebago (rr).

rar. GRACILLIMUM W. & G. S. West, PI. 47, Figs. 8-11 ; PI. 48, Figs. 1-2.
Jour, of Bot. 33: 52. 1895.

Cells very narrow, never wider than the processes. Body of margi-
nal cells curved outwards, with two long, somewhat converging processes
that have parallel or slightly convex sides. Interior cells like those of
margin but with somewhat shorter processes. Perforations of coenobe
very large. (Euplanktont).

Cells 10-22 /x broad, 12-32 /* long. Diam. 16-celled coenobia 65-140 /*.

Clam (rr), Pine Tree (sss), Travis (r).

The perforations of the coenobe and the extension of the processes
are the greatest in this variety. The varieties clathratum, reticidatum,
and gracillimum are not sharply defined and it is possible, taking the
collections as a whole, to arrange a series that grades almost impercept-
ibly from the typical form to the variety gracillimum. The individuals
from any one lake, however, generally vary within fairly narrow limits
so I feel that these varieties should be recognized instead of putting
them in one collective species without varieties.

var. ROTUNDATUM Lucks. PI. 46, Fig. 17.

Jahrb. d. Westpr. Lehrervereins f. Naturk. 2-3: 31. 1907; Nitardy, Beih. z.
Bot. Cent. S22: pi. 9, fig. 11. 1914.

Projections of marginal cells markedly convex and capitate instead
of parallel. (Tychoplanktont).

Oconomowoc (rrr), Horseshoe (1) (rr).

WISCONSIN PHYTOPLANKTON 173

var. COHAERENS Bohlin. PL 48, Figs. 3-4.

Bih. t. Kgl. Sv. Vet.-Ak. Handl. 23, Afd. 3, No. 7: 31, pi. 2, fig. 1. 1897.

Pediastrum duplex var. reticulatum forma cohaerens (Bohlin) Brunnthaler,
in Pascher, D. Siisswasserfl. Deutschl., osterr. u. d. Schw. 52: 95, fig. 57e. 1915.

Coenobia circular to oval, of 16-32-64 cells, with median-sized inter-
cellular spaces. Wall of cells covered with short, linear, concentrically
arranged granules. (Facultative Planktont).

Cells 12-22 p broad; 13-24 f*. long.

Pine Tree (r).

PEDIASTRUM BIRADIATUM Meyen. PI. 48, Figs. 5-8.

Nova Acta Phys.-Med. Ac. Caes.-Leop. Nat. Cur. 142: 773, pi. 43, figs. 21-22. 1829.
Pediastrum rotula (Ehrenberg) A. Braun emend. Alg. unicell. 101, pi. 6,
figs. 2-3, 5-7, 10, 12-14. 1855.

Coenobia of 4-8-16-32-64 cells, with medium sized openings between
cells. Marginal cells in contact with one another at base only, with
two long projections that are dilate and incised at the apex. Interior
cells as those of the margin but apices of projections neither dilate nor
incised, in contact with other cells at base and ends of projections only.
Cell wall smooth. (Facultative Planktont).

Cells 10-22 p, broad, 15-30 p. long. Diam. 32-celled coenobia 80-150 /A.

Balsam (rrr), Bear (3) (rr), Big McKenzie (rr), Lac du Flambeau (rr),
Mud (2) (rr), Nancy (rrr), Pokegama (1) (rrr), Wolf (rrr).

This species resembles P. duplex var. reticulatum in the perforation
of the disc but differs in the deep incision of the marginal cell projec-
tions. Perfect colonies are seldom seen since apices of projections of
certain interior cells are free and have the same dilation and incision
that is found in the marginal cells. The number of cells in the colony
is generally stated as 8-16-32 but the coenobia in the plankton of Wis-
consin lakes are 32- or 64-celled except in very rare cases.

PEDIASTRUM TETRAS (Ehrenberg) Ralfs. PI. 48, Figs. 9-12.
Ann. & Mag. of Nat. Hist. 14: 469, pi. 12, fig. 4. 1844.

Coenobia rectangular, oval or circular; without perforations; of
4_8-16-32 (generally 4-8) cells. Outer face of marginal cells with a
single deep linear to cuneate incision, the halves of the outer face
slightly to deeply emarginate. Interior cells with a single deep linear
incision and 4-6 straight sides. Cell wall smooth. (Tychoplanktont).

Diam. cells 8-15 /*.

Blake (rrr), Browns (rrr), Chain (rrr), Chetek (rr), Cochrane (rrr), Hill-
man (rrr), Horse (rrr), Horseshoe (2) (rrr), Kimball (rrr), Lindy (rrr),

174 WISCONSIN PHYTOPLANKTON

Little Doctor (rr), Mendota (rrr), Palmer (rrr), Pewaukee (rrr), Pine (2)
(rr), Pokegama (1) (rr), Poor Farm (rr), Tied Canoe (rrr).

The four projections in the outer face of marginal cells are due to a
deep emargination of the two halves. This, coupled with the deep in-
cision of all cells, at once separates the species from others of the genus.
The alga does not thrive under plankton conditions although it is com-
mon in ditches and ponds of the state.

var. OBTUSATA Raciborski.

Akad. Umiej. w. Krakowie 2O: 32. 1889; Printz, Skr. Vidensk. i Kristiana
Mat.-Naturv. Kl. 19131, No. 6: 78, pi. 6, fig. 153. 1914.

Cells larger than typical form, sometimes expanded at base. Halves
of outer face of marginal cells entire or very slightly emarginate.
( Ty choplanktont ) .

Diam. ceUs 14-18 p ; length 18-22 /*.

Beaverdam (rrr).

var. TETRAODON (Corda) Hansgirg. PI. 48, Figs. 13-14; PI. 49, Figs. 1-2.

Prodr. d. Algenfl. v. Bohmen 1: 112. 1888.

Euastrum tetraodon Corda, Almanach de Carlsbad 9: 238, pi. 2, fig. 9. 1839.

Coenobia generally 8-celled. Incision of cells deep, and with projec-
tions adjacent to incision very pronounced on marginal cells. (Facul-
tative Planktont) .

Diam. marginal cells 8-15 /* ; length 12-18 /x.

Pine Tree (rr), Travis (r).

There is no question that my figures of the organism are identical
with the one that Nitardy (Beih. Bot. Cent. 322 : 123, pi. 5, fig. 8. 1914)
has reproduced from Corda. The variety is sharply defined through
the greater development of the projections.

EUASTROPSIS Lagerheim 1894.

Coenobia free-floating, 2-celled. Cells flattened, approximated at the
bases, distal end free and deeply emarginate. Chloroplast single, pari-
etal, with one pyrenoid.

Asexual reproduction by division of cell contents into 2-4-8-16-32
zoospores which are extruded in a vesicle and on becoming quiescent
join in pairs to form the characteristic coenobe.

Sexual reproduction unknown.

WISCONSIN PHYTOPLANKTON 175

EUASTROPSIS RICHTERI (Schmidle) Lagerheim. PI. 49, Fig. 3.
Tromso Museums Aarshefter 17: 20, pi. 1, figs. 8-27. 1894.

Cells trapezoidal, outer face deeply emarginate. (Tyehoplanktont).
Cells 4.5-25 /* broad, 5-20 /* long. Coenobia 4.5-25 ^ broad, 10-40
jt long.

Kegonsa (rrr).

It is quite possible to mistake 2-celled Pediastrum colonies for
E. Richteri, but since such Pediastrum colonies are of very rare occur-
rence the similarity of the two is not apt to lead to confusion.

Family PLANOSPORACEAE.

Cells solitary or gregarious; ovoid, pyriform, fusiform, cylindrical,
or hemispherical ; epiphytic, endophytic, or epizootic. Cells capable of
growth but incapable of division after their formation. Generally with
a single chloroplast with one or more pyrenoids.

Asexual reproduction by division of cell contents to form many zoo-
spores.

Only one genus, Characium, is found in the plankton of the state.

CHARACIUM A. Braun 1849.

Cells sub-spherical, ovoid, pyriform, fusiform, or cylindrical; soli-
tary or gregarious; epiphytic or epizootic; generally attached to sub-
stratum by a more or less elongate stipe, rarely sub-sessile. Chloroplast
parietal and laminate to cup-shaped in young cells; later expanded to
fill entire cell : with one or more pyrenoids. Cells at times with several
ehloroplasts.

Asexual reproduction by repeated division of cell contents into 8-16-
32-64-128 zoospores that are liberated through a lateral or apical pore.
Zoospores swarming but a short time and then coming to rest on sub-
stratum and developing into vegetative cells.

Microgametes reported but doubtful.

KEY TO THE SPECIES.

Epiphytic upon other algae.

Cells ovoid C. STIPITATUM

Cells lunate C. CUBVATUM

Epizootic upon crustaceans.

Apices of cells rounded C. CYLTNDBICFM

Apices of cells produced into a fine seta.

Stipe simple C. LIMNETICUM

Stipe ending in filiform rhizoids C. GBACILIPB»

176 WISCONSIN PHYTOPLANKTON

CHARACIUM STIPITATUM (Bachmann) Wille. PI. 49, Figs. 4-7.

in Engler & Prantl, Nat. Pflanzenfam. I3 (Nachtr.); 45. 1909; G. M. Smith,
Bull. Torr. Bot. Cl. 43: 472, pi. 24, flgs. 4-6. 1916.

Cells spherical to pyriform, with a delicate hyaline stipe somewhat
longer than the cell. Chloroplast single, parietal, cup-shaped, always
on the side away from the stipe ; pyrenoid single. Zoospores broadly
ovoid, biciliate, with a cup-shaped chloroplast at the posterior end.
(Euplanktont).

Epiphytic upon and embedded within the gelatinous envelope of
Coelosphaerium Naegelianum Unger.

Cells 5-8 p. broad. Stipe 10-16 /u. long.

Amicoy (r), Balsam (rr), Beartrap (rr), Beaverdam (s), Big (rr), Big
McKenzie (ss), Clam (ss), Devils (2) (ss), Horseshoe (1) (ss), Horseshoe
(2) (rr), Long (2) (ss), Kawaguesaga (ss), North Twin (sss), Pardee (r),
Pike (rr), Pokegama (1) (s), Pokegama (2) (r), Poplar (rrr), St. Croix (r),
Sand (4) (rr), Sishebogema (rr).

In one case the alga was found upon Oocystis but in all others it was
inside the gelatinous envelope of Coelosphaerium Naegelianum Unger.
When the alga grows upon Coelosphaerium the colony is apt to be in-
fested with 50-100 individuals as a rule. The alga was originally des-
cribed as a Chlamydomonas species but since the sessile phase is the
dominant one of the life cycle it is better placed as a Characium species.
Although found at only one station in Europe it is widely distributed
in northern Wisconsin.

CHARACIUM CURVATUM G. M. Smith. PI. 49, Figs. 8-15.
Trans.- Wis. Acad. Sci., Arts, & Lett. 191: 641, pi. 11, figs. 6-13. 1918.

Cells lunate or recurved, with acute or sub-acute apices. Stipe hya-
line, thick, tubular or conical, sometimes irregular in outline. Chloro-
plast single, parietal, laminate to cup-shaped ; with or without a pyre-
noid. ( Euplanktont) .

Epiphytic upon Coelosphaerium Naegelianum Unger, Dictyosphaer-
ium pulchellum Wood, and Phaeococcus planctonicus W. & G. S. West.

Cells 3-6 p. broad, 8-18 ^ long (without stipe), 13-22 /u. long with
stipe.

Bear (1) (rr), Birch (2) (cc), Chain (rr), Chetac (aa), Chetek (rr), Clam
(sss), East (rr), Horseshoe (1) (ss), Lindy (rr), Mud (1) (rr), South Crab
(ss), Wild Goose (rr).

An alga that resembles C. stipitatum in the manner of growth but
one which is found upon a wider range of genera. It also differs in the
curved cells and the broader stipe.

WISCONSIN PHYTOPLANKTON 177

CHAKACIUM CYLJNDRICUM Lambert. PI. 49, Figs. 16-19.
Rhodora 11: 70, pi. 79, figs. 1-2, 7-8, 10-13, 23-25. 1909.

Cells cylindrical, with, rounded apices, base tapering slightly into a
short stipe without a basal disc. Chloroplasts 1-16, parietal, disciform
to laminate, without pyrenoids. (Euplanktont).

On DiapJianosoma brachyura and Branchipus vernalis.

Cells 8-20 n broad, 20-430 p. long.

Howey (cc).

The lack of a pyrenoid suggests Characiopsis but the bright green
color of the chloroplast shows that the alga is one of the Chlorophyceae
and so is placed among Characium species. Young cells contain a sin-
gle chloroplast but with growth there is an increase in the number of
chloroplasts and all stages between cells with a single chloroplast and
those with sixteen may be found on the same crustacean. Lambert
holds that this condition is a stage in the division into zoospores but
in my opinion it is the normal condition of the adult cell. Another
point of interest is the position of the alga upon the host since it is
only found on the tail of the crustacean.

CHARACIUM LIMNETICUM Lemmermann. PL 49, Figs. 25-29.
Bot. Not. 1903: 81, pi. 3, figs. 7-10. 1903.

Cells broadly fusiform, lunate, rarely straight; apex produced into
a single delicate hyaline seta; base a delicate stipe without basal discs.
1-8 parietal band-shaped chloroplasts, each containing 1-2 pyrenoids.
(Euplanktont).

Cells 5-14 /* broad, 25-110 /* long; stipe 5-10 p long.

On Diaphanosoma brachyura.

Boulder (rr), Browns (rr), Delavan (rrr).

Lemmermann describes the chloroplast as single but reports a divi-
sion of the chloroplast prior to division. I have found that in all nor-
mal adult cells of C. limneticum, C. gracilipes, and C. cylindricum there
is more than one chloroplast.

The species is very closely related to C. gracilipes but is much
smaller, proportionally broader, and has a simple stipe. It is very
probable that Raphidium longissimum var. septatum Chodat (Ankistro-
desmus longissimum var. septatum (Chodat) Brunnthaler) is a cell of
C. limneticum broken off from the crustacean during collection.

12

178 WISCONSIN PHYTOPLANKTON

CHARACIUM GRACILIPES Lambert. PI. 49, Figs. 20-24.
Rhodora 11: 65, pi. 79, figs. 3-6, 9, 14-22. 1909.

Cells straight or curved with the median portion fusiform; apex
tapering into a long seta and base attenuated to a filiform stipe. Chloro-
plast parietal, band-shaped, 1-32 per cell; with one pyrenoid in each
chloroplast. (Euplanktont).

On Diaphanosoma brachyura.

Cells 5-14 n broad, 70-480 /* long.

Howey (cc).

This alga was found on the same organism and at the same time as
C. cylindricum. It was confined to the forward appendages while
C. cylindricum was found at the tail only.

Order ULOTRICHALES.

Cells usually in a simple or branched thallus, rarely forming disci-
form thalli one cell in thickness. Thallus generally attached, rarely
free-floating; naked, or enclosed by a tough and leathery or copious
and gelatinous, homogeneous or lamellated envelope. Cells generally
with a single parietal laminate to cup-shaped chloroplast with one or
more pyrenoids. Cell shape usually cylindrical with flattened ends,
rarely cylindrical with rounded ends, spherical or cubical.

Asexual reproduction by vegetative cell division, by a division of
vegetative or special cells to form 2-16 bi- or tetraciliate zoospores, and
by aplanospores.

Sexual reproduction either isogarnous by a division of cell contents
to form bi- or tetraciliate zoogametes ; or heterogamous by the fusion of
tetraciliate zoogametes of different size or the union of large non-motile
oospheres and small biciliate antherozoids.

KEY TO THE FAMILIES.

Ctlls united to form simple filaments ULOTRICHACEAE

Cells united to form branching filaments.

Sexual reproduction by isogamous zoogametes CHAETOPHOBACEAE

Sexual reproduction by heterogamous zoogametes APHANOCHAETACEAE

Family ULOTRICHACEAE.

Cells united to form simple free-floating or sessile filaments which
are enclosed at times by a copious, hyaline, homogeneous or radially
fibrillar, gelatinous envelope. Cell shape spherical to cylindrical with
rounded or flattened ends. Walls of cells delicate or thick, homogen-

WISCONSIN PHYTOPLANKTON 179

ecus or lamellated. Cells containing a nucleus and one parietal, lami-
nate or cup-shaped chloroplast with one or more pyrenoids.

Asexual reproduction by vegetative cell division, aplanospores or
biciliate zoospores.

Sexual reproduction isogamous, by a fusion of bi- or tetraciliate zoo-
gametes.

ULOTHEIX Kiitzing 1833.

Filaments simple, free-floating or with the basal cell modified to form
a hold- fast. Cells cylindrical, with flattened end walls, united to form
simple filaments that are the same diameter throughout. Wall of cells
delicate or thick, homogeneous or lamellated, without a gelatinous outer
layer. Chloroplast single, parietal, laminate, with one or more pyre-
noids. Cells uninucleate.

Asexual reproduction by the division of cell contents to form 1-32
aplanospores and bi- or tetraciliate zoospores.

Sexual reproduction isogamous, by a fusion of biciliate zoogametes.

KEY TO THE SPECIES.

Filaments 11-45 M in diameter U. ZONATA

Filaments 5-7 ft, in diameter U. SUBCONSTEICTA

ULOTHRIX ZONATA (Weber & Mohr) Kiitzing. PI. 50, Fig. 6.
Flora 16: 519. 1833; Hazen, Mem. Torr. Bot. Cl. 11: 147, pi. 20, figs. 1-4. 1902.

Filaments attached or free-floating and forming greenish masses.
Cells disciform to cylindrical, % to !-,'•» times as long as broad. End
walls of cells straight, side walls straigi.it or slightly convex in older
cells. Chloroplast forming a broad or narrow pariciai annular girdle
containing several pyrenoids. Wall of cell thick, generally homo-
geneous but at times lamellated in structure. (Tychoplanktont).

Mature cells 11-45 p. in diameter.

Mendota (rrr).

ULOTHRIX SUBCONSTRICTA G. S. West. PI. 50, Figs. 4-5.
Jour, of Bot. 53: 82, figs. 6A-6c. 1915.

Filaments free-floating, narrow, slightly constricted at cross walls of
cells, with or without a homogeneous gelatinous envelope. Cells elon-
gate, 2-6 times as long as broad, slightly inflated at the poles. Chloro-
plast single, parietal, laminate, with irregular edges and occupying
the median two thirds of the cell. With or without 1-2 pyrenoids.
Cell wall very delicate. (Facultative Planktont).

180 WISCONSIN PHYTOPLANKTON

Cells 5.7-9 fji broad.

The specimens that I have found in our lakes differ somewhat from
those described by West since the cells are not slightly dilate at the
poles and the chloroplasts usually contain pyrenoids. The Wisconsin
organism does not seem sufficiently differentiated, however, to warrant
the description of a new variety or species. This alga is of particular
interest since it is the only one of the order which has become established
as a true member of the plankton.

Family CHAETOPHORACEAE.

Cells united to form branching filamentous, discoidal or pareuchyma-
tous thalli. Branches of thallus generally attenuated at apices and
sometimes ending in long hair-like processes. Thallus naked or en-
closed in a copious, hyaline, homogeneous, gelatinous envelope. Cell
shape ordinarily cylindrical with flattened ends. Chloroplast single,
parietal and laminate to girdle-shaped; wdth one or more pyrenoids.
Nucleus single.

Asexual reproduction by aplanospores and bi- or tetraciliate zoo-
spores.

Sexual reproduction isogamous, by a fusion of biciliate zoogametes.

STIGEOCLONIUM Kiitzing 1843.

Thallus free-floating or attached, with branches scattered and not
arising in dense tufts. Thallus without an appreciable difference in
size between the main stem and minor branches ; covered with a homo-
geneous, hyaline, gelatinous envelope. Cells cylindrical to disciform,
gradually decreasing in diameter towards the apex and with terminal
cells conical or elongated to hair-like unseptate proeesses. Chloroplast
single, parietal ; gridle-shaped and filling median portion of older cells ;
completely filling younger cells. Each chloroplast generally containing
several pyrenoids.

Asexual reproduction by aplanospores and tetraciliate zoospores.

Sexual reproduction isogamous, by the fusion of biciliate zoogametes.

STIGEOCLONIUM LUBRICUM (Dillwyn) Kiitzing. PL 50, Fig. 7.

Phycol. germ. 189. 1845.

Myxonema, lubricum (Dillw.) Fries. Hazen, Mem. Torr. Bot. Cl. 11: 195,
p7. 28, figs. 1-2. 1902.

Filaments forming dark green tufts up to 30 cm. long. Filaments
rauch branched and branches usually opposite, rarely single. Cells of
main filament at base of branches sub-spherical, shorter than other cells.

WISCONSIN PHYTOPLANETON 181

.Branchlets abundant, opposite, scattered in basal portion, dense in dis-
tal, oi:'-y slightly narrower than the branch from which they arise and
with terrmual cell conical or setiferous. Lower cells of main branch
swollen %--4 times as long as broad, with a girdle-like chloroplast in
median portion. (Tychoplanktont).

Main branches 14r-16.5 /* broad; branchlets 6-7 p broad.

Mendota (rrr), Wild Goose (rrr).

Family APHANOCHAETACEAE.

Thallus epiphytic, generally upon other algae, creeping in habit and
composed of simple or irregularly branching filaments that taper from
the center to short, narrow terminal cells that do not end in terminal
setLe;. Central cells of filament spherical to spherical-cylindrical ; those
towards the end cylindrical with straight or convex sides; terminal
cells conical. Cells generally bearing one or more long, hyaline, un-
septate setae with swollen bases. Chloropast parietal, completely fill-
ing the cell, or gridle-like and in the median portion; generally with
ID ore than one pyrenoid.

Asexual reproduction by tetraciliate zoospores or aplanospores.

Sexual reproduction heterogamous, by the fusion of tetraciliate zoo-
gametes that are markedly different in size.

The family contains the single genus ApJianochaeie whose characters
are those of the family.

APHANOCHAETE VERMICULOIDES Wolle. PI. 50, Fig. 8.

Preshw. algae of U. S. 119, pi. 105, figs. 9-10. 1887.

Eerposteiron hyalothecae Hansgirg. G. M. Smith, Trans. Wis. Acad. Scl.,
Arts, & Lett. 182: 560. 1916.

Filaments but slightly branched and confined to the peripheral por-
tion and twisted around or arched from the gelatinous envelope of
UyalotJieca filaments. Cells cylindrical, with straight or convex sides
and containing a single chloropJast with 1^4 pyrenoids. Setae very
sparse, rarely more than five on any filament. (Tychoplanktont).

Cells 4^-6 p broad ; 5-12 /* long.

Beaverdam (rr).

All other species of the genus grow directly upon the cells of the
substratum but the wide gelatinous envelope of the Hyalotheca is in
this case sufficiently firm to support the Aphanochaete. The alga has
the appearance of an arching worm crawling along the filament.

182 WISCONSIN PHYTOPLANKTON

Order SIPHONOCLADIALES.

Cells multinucleate, generally cylindrical and united to form simple
or branched thalli that are, at times, quite complicated in structure.
Chloroplasts disciform, parietal and numerous, or united by strands
to form a single reticulate structure. Pyrenoids generally present.

Asexual reproduction by zoospores and aplanospores.

Sexual reproduction isogamous by means of zoogametes; or heter-
ogamous by large non-motile oospheres and small motile antherozoids.

The order is largely marine and only one representative, Cladophora,
has been found in the plankton.

Family CLADOPHORACEAE.

Filaments generally sessile, simple or branched, with septations be-
tween the cells complete. Walls of cells generally heavy, homogeneous
or lamellose, without a gelatinous envelope. Cells with numerous
parietal disciform chloroplasts or a single reticulate chloroplast ; multi-
nucleate ; with a single large central vaeuole.

Asexual reproduction by zoospores and akinetes.

Sexual reproduction isogamous, by means of zoogametes.

CLADOPHORA Kiitzing 1843.

Filaments branched, with the component cells in a single linear series ;
lateral branches arising at distal part of main branch cells and gener-
ally with an abundantly developed system of branching. Growth of
filaments confined to the apical region. Cells cylindrical, several times
as long as broad; multinucleate; with numerous parietal disciform
chloroplasts or the chloroplasts united by processes to form a single
reticulate chloroplast; pyrenoids numerous.

Asexual reproduction by the formation of many biciliate zoospores in
any cell of the filament.

Sexual reproduction isogamous, by means of biciliate zoogametes.

CLADOPHORA GLOMERATA (L.) Kiitzing. PL 50, Figs. 1-3.

Phycol. gener. 266. 1843; Collins, Tufts Coll. Studies 2: 360, pi. 13, fig. 124.
1909.

Branching of filaments fairly dense in lower portion and very dense
at the apex. Ultimate branchlets containing several cells, straight or
slightly incurved, with ends rounded but not markedly attenuated.
Cells of main branches 6-7 times as long as broad, 3-6 times as broad

WISCONSIN PHYTOPLANKTON 183

as branchlets. Zoospore formation confined to terminal and subtermi-
nal cells. (Tychoplanktont).

Diam. main cells 75-100 /*, branchlets 35-50 /x.

Mendota (rr).

Division AKONTAE.

Cells solitary or in filaments, variously shaped, with one or more
grass-green chloroplasts that usually contain more than one pyrenoid.

Asexual reproduction ordinarily by vegetative cell division, rarely by
aplanospores, never by zoospores.

Sexual reproduction isogamous, always by aplanogametes, never by
ciliate zoogametes.

The lack of cilia in every type of reproduction is the great character-
istic of the division. It includes but one order, the Conjugales, which
forms a very homogeneous though diverse group.

Order CONJUGALES.

Cells solitary or in simple filaments; cell shape various, cylindrical
without median constrictions or bilaterally symmetrical and usually
v;ith a median constriction dividing the cell into two symmetrical halves.
Cell wall smooth or variously ornamented, with an inner firm portion
and an outer gelatinous portion that is very copious at times. Chloro-
plasts 1-8, variously shaped, axial or parietal, with one to several pyre-
noids. Nucleus single, at the center of the cell.

Asexual reproduction by vegetative cell division or aplanospores.

Sexual reproduction isogamous, by aplanogametes.

KEY TO THE FAMILIES.

Cells cylindrical, without a median constriction, united to

form simple filaments ZYGNEMACEAE

Cells solitary or in filaments, divided into two symmetri-
cal halves, generally with a median constriction DESMIDIACEAK

(See Part II)

Family ZYGNEMACEAE.

Cells always cylindrical, with ends flattened or replicate, serially
arranged to form simple filaments that occasionally have simple lateral
outgrowths. Filaments generally free-floating though at times attached
by a modification of terminal cell into a basal cell with short rhizoidal
processes. Wall of cell firm, homogeneous, with a narrow or copious,
homogeneous or radially fibrillar, gelatinous covering. Cell contents
consisting of a single nucleus, and one to several chloroplasts that are

184 WISCONSIN PHJTOPLANKTON

either stellate or laminate and axial or parietal. Chloroplasts with one
to many pyrenoids.

Asexual reproduction by vegetative cell division or metamorphosis
of cell contents into a single large aplanospore.

Sexual reproduction isogamous, by metamorphosis of all or a part
of the cell contents into an aplanogamete which fuses with an aplano-
gamete from the same or another filament. Zygote with 2-3 layers,
sometimes germinating immediately but usually after a period of rest.

KEY TO THE GENERA.

Cbloroplast stellate ZYGNEMA

Cbloroplast a longitudinal band.

Chloroplast axial MOTJGEOTIA

Chloroplast parietal SPIBOGYRA

MOUGEOTIA C. A. Agardh 1824.

Cells cylindrical, generally several times as long as broad. Chloro-
plast single, forming an axial plate extending the whole length of the
cell and generally with several pyrenoids.

Conjugation generally scalariform and with the zygote formed in the
conjugation tube. Zygote at times occupying the median portion of
male and female garnetangia as well as conjugation tube. Wall of
zygote of two layers the inner smooth, the outer smooth or sculptured,
hyaline or colored.

MOUGEOTIA VIRIDIS (Kiitzing) Wittrock. PI. 51, Fig. 1.

Bib, Kgl. ST. Vet.-Ak. Handl. 1, No. 1: 39. 1872.

Staurospermum viride Kiitzing. Cooke, Brit. Freshw. Algae 107, pi. 44,
figs. 2a-2c. 1882.

Cells 4-10 times as long as broad. Zygospores normally bounded by
four cells, quadrangular, with concave sides and truncate corners.
(Tychoplanktont) .

Cells 6-8 fji broad. Zygotes 22-32 /* broad.

Okauchee (rrr).

ZYGNEMA C. A. Agardh 1817.

Cells cylindrical, rarely more than twice as broad as long. Filaments
with a terminal cell at times modified to form a holdfast. Cells with
one nucleus and two axial stellate chloroplasts each of which contain
a single pyrenoid. Conjugation lateral or scalariform, with a forma-
tion of zygospores in the conjugation tube or the gametangia. Zygotes
spherical to ellipsoid, wall with three layers.

WISCONSIN PHJTOPLANKTON 185

ZYGNEMA PECTINATUM (Vaucher) C. A. Agardh. PI. 51, Fig. 2.

Synop. algarum Scand. 102. 1817; DeBary, Unters. u. d. Fam. d. Conjugates
77, pi. 1, figs. 15-19. 1858.

Vegetative cells 1-3 times as broad as long. Zygospore formed in
conjugation tube, with rounded ends. Middle layer of zygote wall
brown and scrobiculate. (Tychoplanktont).

Vegetative cells 30-40 /* broad. Zygote 35-^0 /x broad.

Oconomowoc (rrr).

SPIKOGYBA Link 1820.

Cells cylindrical, with end walls a fiat plane or replicate; united to
form simple filaments that may be attached by a modification of the
terminal cell into holdfasts. Length of cells slightly greater than to
several times the breadth. Chloroplasts one to several, parietal, in
long ribbons that extend from end to end in the cell and generally
make several spiral turns. Nucleus single, moored in the center of the
central vacuole by cytoplasmic strands running to the pyrenoids. Chlor-
oplasts with several pyrenoids that are generally in a single median row.

Conjugation sealariform or lateral, with zygote formation in game-
tangia and never in the tube. Zygote spherical, ellipsoid, or cylindri-
cal with rounded ends. Middle layer of zygote hyaline or colored,
smooth or sculptured.

SPIROGYRA PORTICALIS (Miiller) Cleve. PI. 51, Fig. 3.

Nova Acta Reg. Soc. Sci. Upsaliensis 3, Ser., 6: No. 11, 22, pi. 5, figs. 8-13.
1S68.

Length of vegetative cells 2-6 times the breadth. Cells with plane
cross walls and containing a single chloroplast that makes 3-5 turns and
contains numerous conspicuous pyrenoids. Gametangia but little swol-
len when zygospore is mature. Zygospores broadly ovoid to sub-cylin-
drical, with a yellow membrane when mature. (Tychoplanktont).

Diam. cells 30-50 p. Diam. zygospores 40-50 p..

Mendota (rrr).

3S6 WISCONSIN PHYTOPLANKTON

PLATE 1.

Page

Fig. 1. Chroococcus minutus (x 825) 28

Fig. 2. Chroococcus dispersus (x 825) 28

Fig. 3. Chroococcus dispersus var. minor (x 825) 2?

Fig. 4. Chroococcus limneticus (x 825) 29

Fig. 5. Chroococcus limneticus var. subsalsus (x 825) 23

Fig. 6. Chroococcus limneticus var. carneus (x 825) 30

Fig. 7. Chroococcus limneticus var. distans (x 825) 30

Fig. 8. Chroococcus limneticus var. elegans (x 825) 30

Fig. 9. Chroococcus turgidus (x 1000) 31

WISCONSIN SURVEY

BULLETIN 57, PLATE 1

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WISCONSIN SURVEY

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PLATE 2.

Page

Fig. 1. Chroococcus giganteus (x 825 ) 30

Fig. 2. Merismopedia tenuissima (x 1000) 33

Fig. 3. Merismopedia punctata (x 1000) 33

Fig. 4. Merismopedia glauca (x 1000) 32

Fig. 5. Merismopedia elegans (x 1000) 32

Fig. 6. Merismopedia elegans var. major (x 1000) 32

Fig. 7. Aphanocapsa delicatissima (x 1000) 41

Fig. 8. Aphanocapsa elachista var. conferta. (x 1000) 42

Fig. 9. Aphanocapsa pulchra (x 825) 42

Fig. 10. Aphanocapsa endophytica (x 1000) 42

jgg WISCONSIN PHYTOPLANKTON

PLATE 3.

Page

Fig. 1. Aphanocapsa Grevillei (x 825) 43

Fig. 2. Aphanocapsa rivularis (x 825) 43

Fig. 3. Aphanocapsa clachista var. planctonica (x 1000) 42

Figs. 4-5. Coelosphaerium Kuetzingianum (x 825) 34

Fig. 6. Coelospfiaerium Naegeliamim (x 825) 35

Fig. 7. Coelosphaerium dubium (x 825) 35

WISCONSIN SURVEY

BULLETIN 57, PLATE 3

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COCKAYNE. BOSTON

WISCONSIN SURVEY

BULLETIN 57, PLATE 4

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WISCONSIN PHYTOPLA.NKTON 189

PLATE 4.

Page

Fig. 1. Coelosphaerium Naegelianum (x 825) 35

Figs, 2-3. Gomphosphaeria aponina (x 825) 37

Fig. 4. Gomphosphaeria aponina var. cordiformis (x 825) 37

Fig. 5. Gomphosphaeria lacustris (x 825) 36

Fig. 6. Microcystis aeruginosa var. major (x 825) 40

190 WISCONSIN PH7TOPLANKTON

PLATE 5.

Page

Figs. 1-2. Microcystis aeruginosa (Fig. 1, x 825; fig. 2, x ISO 39

Fig. 3. Nicrocystis flos-aquae (x 825) 39

Fig. 4. Microcystis incerta (x 825) 40

Fig. 5. ApJianothece prasina (x 825) 45

Fig. 6. Aphanothece nidulans var. endophytica (x 1000) 44

WISCONSIN SURVEY

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WISCONSIN PHTTOPLANETON

191

PLATE 6.

Fig. 1. ApfianotJiece nidiilans (x 1000)

Fig. 2. Aphanothece stagnina (x 825)

Fig. 3. Aphanothece clathrata (x 1000)

Fig. 4. Rnabdoderma lineare (x 1000)

Fig. 5. Gloeothece linearis (x 1000)

Fig. 6. Gloeoth%ce linearis var. composita (x 1GOC)

Fig. 7. Dactylococcopsis rapliidioides (x 825)

Figs. 8-10. Dactylococcopsis acicularis (x 1000)

Page
44
45
44
47
46
46
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48

192 WISCONSIN PH7TOPLANKTON

PLATE 7.

Page

Fig. 1. Spirulina major (x 1000) 50

Fig. 2. Spirulina princeps (x 1000 ) 50

Figs. 3-5. Oscillatoria prolifica (x 825) 51

Fig. 6. Oscillatoria tennis (x 825) 52

Figs. 7-8. Oscillatoria tennis var. tergestina (x 825) 52

Figs. 9-11. Lyngbya limnetica (x 1000) 52

Figs. 12-13. Lyngbya contorta (x 1000) 53

Figs. 14-15. Lyngbya Birgei (x 825) 54

WISCONSIN SURVEY

BULLETIN 57, PLATE 7

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SMITH — ALGAF

COCKAYNE. BOSTON

WISCONSIN SURVEY

BULLETIN 57, PLATE 8

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10

SMITH — ALGAE

COCKAYNE. BOSTON

WISCONSIN PHYTOPLANKTON 193

PLATE 8.

Paga

Fig. 1. Trichodcsmium lacustre (x 1000) 54

Fig. 2. Anabaena plantonica (x 825) 55

Fig. 3. Anabaena Bornetiana (x 825) 58

Figs. 4-5. Anabaena Levanderi (x 825) 58

Fig. 6. Anabaena macrospora var. robusta (x 825) 57

Fig. 7. Anabaena affinis (x 825) 57

Fig. 8. Anabaena limnetica (x 825)

Figs. 9-10. Anabaena augstumalis var. marchica (x 825) 58

13

194 WISCONSIN PHYTOPLANKTON

PLATE 9.

Page
Figs. 1-3. Anabaena spiroides var. crassa (Fig. 1, x 825, figs. 2-3, x 400) 59

Figs. 4-5. Anabaena circinalis (Fig. 4, x 825, fig. 5, x 400) 59

Fig. 6. Anabaena circinalis var. macrospora (x825) 60

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PLATE 10.

Page

Fig. 1. Anabaena circinalis var. macrospora (x 400) 60

Figs. 2-4. Anabaena flos-aquae (Figs. 2-3, x 825; fig. 4, x 400) 60

Figs. 5-7. Anabaena flos-aquae var. Treleasii (x 825) 60

Fig. 8. Anabaena Lemmermanni (x 825) 61

196 WISCONSIN PHYTOPLANKTON

PLATE 11.

Page

Fig. 1. Anabaena Lemmcrmanni (x 400) 61

Figs. 2-4. Aphanizomenon flos-aquae (Fig. 2, x 400; figs. 3-4, x 1000) . . 61
Figs. 5-6. Gloeotrichia ec.Mnulata (x 400) 63

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PLATE 12.

Page

Fig. 1. Chrysamoeba radians (x 1000) 67

Fig. 2. Mallomonas producta (x 500) 68

Fig. 3. Mallomonas producta var. marchica (x 500) 68

Fig. 4. Mallomonas alpina (x 500) 68

Fig. 5. Mallomonas tonsurata (x 500) 68

Fig. 6. Mallomonas caudata (x 500) 69

Figs. 7-8. Chrysosphaerella longispina (Fig. 7, x 400; fig. 8, x 1000).. 69

Figs. 9-10. Synura uvella (Fig. 9, x 1000, fig. 10, x 400) 70

198 WISCONSIN PRYTOPLANKTON

PLATE 13.

Page

Figs. 1-4. Uroglenopsis americana (Fig. 1, x 400; figs- 2-4, x 1000) 71

Figs. 5-6. Dinobryon calciformis (x 1000) 73

Figs. 7-9. Dinobryon tabellariae (x 1000) 73

Fig. 10. Dinobryon bavaricum (x 400) 73

Fig. 11. Dinobryon stipitatum (x 400) 74

Fig. 12. Dinobryon sociale (x 400) 74

Fig. 13. Dinobryon setularia (x 400) 74

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PLATE 14.

Page

Fig. 1. Dinobryon setularia (x 400) 74

Fig. 2. Dinobryon divergens (x 400) 75

Figs. 3-4. Hyalobryon mucicola (x 1000) 75

Fig. 5. Phaeococcus plantonicus (x 1000) 76

Fig. 6. Rhizochrysis limnetica (x 400) 77

Figs. 7-8. CJirysidiastrum catenulatum (Fig. 7, x 500, fig. 8, x 1000)... 78

200 WISCONSIN PHYTOPLANKTON

PLATE 15.

Page

Figs-. 1-3. Chlorochromonas minuta (x 1000) 80

Fig. 4. Peroniella planctonica (x 1000) 81

Fig. 5. Botryococcus Braunii (x 400) 84

Figs. 6-7. Botryococcus protuoerans var. minor (Fig. 6 x 500, fig. 7 x

1000) 85

Fig. 8. Botryococcus sucleticus (x 400) 83

Fig. 9. Cliloro'botrys limneticus (x 1000) 82

Fig. 10. Chlorobotrys regularis (x 1000) 82

Fig. 11. OpJi iocytium parvulum (x 1000) 86

Figs. 12-13. Ophiocytium capitatum (x 1000) 86

Figs. 14-16. Ophiocytium capitatum var. longispinum (x 1000)

Figs. 17-18. Tribonema minus (x 1000) 87

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201

PLATE 16.

Fig. 1. Carteria cordiformis (x 1000)

Figs. 2-4. Carteria Klebsii (x 1000)

Figs. 5-7. CJilamydomonas dinobryoni (x 1000)

Fig. 8. Chlamydomonas glotosa (x 1000)

Figs. 9-10. Cniamydomonas Snowii (x 1000)...

Figs. 11-13. Chlamydomonas epiphytica (x 1000)

Figs. 14-15. Gonium pectorale (x 500)

Figs. 16-17. Pandorina morum (x 400)

Page
92
93
01
90
91
91
94
95

202 WISCONSIN PH7TOPLANKTON

PLATE 17.

Page
Figs. 1-3. Pleodortna californica (x 400) 97

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BULLETIN 57, PLATE 17

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BULLETIN 57, PLATE 18

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SMITH — ALGAE

COCKAYNE, BOSTON

WISCONSIN PHYTOPLANKTON 203

PLATE 18.

Page

Fig. 1. Volvox mononae (x 266 ) 99

Fig. 2. Volvox aureus (x 266) 98

Figs. 3-5. Volvox fflobator (x 266) 98

204 WISCONSIN PHYTOPLANKTON

PLATE 19.

Page

Fig. 1. Eudorina elegans (x 500) 96

Fig. 2. Gloeocystis gigas (x 1000) 101

Figs. 3-4. Sphaerocystis Schroeteri (x 1000) 101

Figs. 5-6. Tetraspora lacustris (x 500) 102

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BULLETIN 57, PLATE 19

(•:: \

1 ' I

O

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BULLETIN 57, PLATE 2O

--..,

11

12

13

SMITH— ALGAE

COCKAYNE, BOSTON

WISCONSIN PHYTOPLANKTON 205

PLATE 20.

Paga

Figs. 1-2. G-loeocystopsis Umneticus (x 1000) , 103

Figs. 3-6. Planktosphaeria gelatinosa (x 1000) 103

Figs. 7-10. Asterococcus Umneticus (Fig. 7, x 500; figs. 8-10, x 1000) . 104

Figs. 11-12. Dictyosphaerium Ehrenbergianum (x 1000) 105

Fig. 13. Dictyosphaerium pulcUellum (x 1000) 105

206 WISCONSIN PHTTOPLANKTON

PLATE 21.

Page

Fig. 1. DictyospMerium pulchellum (x 1000) 105

Figs. 2-3. Westella linearis (x 1000) 107

Fig. 4. Westella botryoides (x 1000) 107

Fig. 5. Dimorphococcus lunatus (x 1000) - 106

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BULLETIN 57, PLATE 21

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BULLETIN 57, PLATE 22

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WISCONSIN PHYTOPLANETON 207

PLATE 22.

Page

Fig. 1. Chlorella vulgaris (x 1000) 108

Fig. 2. Trochiscia reticularis (x 1000) 109

Fig. 3. Oocystis pusilla (x 1000) Ill

Fig. 4. Oocystis Borgei (x 1000) Ill

Fig. 5. Oocystis elliptica (x 1000) Ill

Fig. 6. Oocystis parva (x 1000) 112

Fig. 7. Oocystis gloeocystiformis (x 1000) 112

Figs. 8-9. Oocystis lacustris (x 1000) 112

Fig. 10. Oocystis submarina (x 1000) 113

Fig. 11. Oocystis solitaria (x 1000) 113

Figs. 12-13. Oocystis crassa (x 1000) 113

WISCONSIN PHYTOPLANKTON

PLATE 23.

Page

Figs. 1-2. Oocystis eremosphaeria (x 1000) 113

Fig. 3. Oocystis panduriformis var. minor (x 1000) 114

Figs. 4-5. Oocystis natans var. major (Fig. 4, x 500; fig. 5, x 1000).. 114

Figs. 6-7. Nephrocytium Agardhianum (x 1000) 114

Figs. 8-9. Gloeotaenium, Loitles'bergerianum (x 400) 115

Figs. 10-13. Tetraedron muticum var. punctulatum (x 1000) 116

Figs. 14-16. Tetraedron trigonum (x 1000) 116

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BULLETIN 57. PLATE 23

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BULLETIN 57, PLATE 24

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WISCONSIN PHYTOPLANKTON 201)

PLATE 24.

Page

Figs. 1-4. Tetraedron trigonum var. setigerum (x 1000) 117

Figs. 5-9. Tetraedron trigonum var. gracile (x 1000) 117

Figs. 10-13. Tetraedron minimum (x 1000) 118

Fig. 14. Tetraedron regulare (x 1000) 118

Figs. 15-16. Tetraedron regulare var. incus (x 1000) 118

Figs. 17-18. Tetraedron regulare var. torsum (x 1000) 119

Figs. 19-22.. Tetraedron victorieae var. major (x 1000)

14

210 WISCONSIN PHYTOPLANKTON

PLATE 25.

Page

Fig. 1. Tetracdron victorieae var. major (x 1000) 119

Figs. 2-3. Tetracdron verrucosum (x 1000) 119

Figs. 4-7. Tetraedron caudatum (x 1000) 120

Figs. 8-12. Tetracdron caudatum var. longispinum (x 1000) 120

Figs. 13-17. Tetraedron pentaedricum (x 1000) 120

Fig. 1?. Tetraedron hastatum (x 1000) 121

Figs. 19-21. Tetracdron hastatum var. palatinum (x 1000) 121

Figs. 22-24. Tetraedron constrictum (x 1000) 122

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BULLETIN 57, PLATE 26

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WISCONSIN PHYTOPLANETON

PLATE 26.

Page

Figs. 1-5. Tetracdron gracile (x 1000) 122

Figs. 6-7. Tetraedron lobulatum (x 1000) 122

Fig. 8. Tetraedron lo~bulatum var. polyfurcatum (x 1000) 123

212 WISCONSIN PHYTOPLANKTON

PLATE 27.

Page

Figs. 1-3. Tetraedron limneticum (x 1000) 123

Figs. 4-5. Tetraedron planctonicum (x 1000) 123

Fig. 6. Tetraedron enorme (x 1000) 124

Figs. 7-8. Polyedriopsis spinulosa (x 1000) 124

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BULLETIN 57, PLATE 28

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PLATE 28.

Page

Figs. 1-3. Micractinium pusillum (x 1000) 125

Fig. 4. Micractinium quadrisetum (x 1000) 126

214 WISCONSIN PHYTOPLANKTON

PLATE 29.

Page

Fig. 1. Micractinium pusillum var. elegans (x 1000) 126

Figs. 2-3. Golenkinia radiata (x 1000) 127

Figs. 4-5. Golenkinia paucispina (x 1000) 127

Figs. 6-8. Acanthosphaera Zachariasi (x 1000) 128

Figs. 9-11. Ecfiinospnaerella limnetica (x 1000) 128

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BULLETIN 57, PLATE 29

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BULLETIN 57, PLATE 3O

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WISCONSIN PHYTOPLANKTON 215

PLATE 30.

Page

Figs. 1-2. Lagerheimia citriformis (x 1000) 130

Figs. 3-4. Lagerheimia su'bsala (x 1000) 130

Figs. 5-7. Lagerlieimia Droescheri (x 1000) 131

Figs. 8-9. Lagerheimia longiseta (x 1000) 130

Figs. 10-12. Lagerheimia longiseta var. major (x 1000) 130

216 WISCONSIN PEYTOPLANKTON

PLATE 31.

Page

Figs. 1-2. Lagerheimia ciliata (x 1000) 129

Fig. 3. Lagerheimia ciliata var. minor (x 1000) 129

Fig. 4. Franceia ovalis (x 1000) 131

Fig. 5. Selenastrum gracile (x 1000) 133

Figs. 6-7. Selenastrum Bibraianum (x 1000) 133

Figs. 8-10. Selenastrum Westii (x 1000) 133

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BULLETIN 57, PLATE 32

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WISCONSIN PHYTOPLANKTON 217

PLATE 32.

Page

Fig. 1. Ankistrodesmus falcatus (x 1000) 134

Fig. 2. Ankistrodesmus falcatus var. tumidus (x 1000) 135

Figs. 3-5. Ankistrodesmus falcatus var. mirabilis (x 1000) 135

Figs. 6-7. Ankistrodesmus spiralis ,(x 1000) 135

Fig. 8. Closteriopsis longissima var. tropica (x 400) 136

Figs. 9-11. Scnroederia Judayi (x 1000) 137

Fig. 12. Schroederia setigera (x 1000) 137

218 WISCONSIN PHYTOPLANKTON

PLATE 33.

Page

Figs. 1-2. Quadrigula Pfitzeri (x 1000) 138

Fig. 3. Quadrigula Chodati (x 1000) 138

Figs. 4-6. Quadrigula lacustris (Fig. 4, x 500; figs. 5-6, x 1000) 139

Fig. 7. Elaktothrix viridis (x 825) 140

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BULLETIN 57. PLATE 33

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BULLETIN 57, PLATE 34

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PLATE 34.

Page

Figs. 1-3. ElaJctothrix gelatinosa (Figs. 1-2, x 500; fig. 3, x 1000) 139

Fig. 4. Kirchneriella lunaris (x 1000) 141

Fig. 5. KircUneriella lunaris var. dianae (x 100 141

220 WISCONSIN PHYTOPLANETON

PLATE 35.

Page

Fig. 1. Eirchneriella lunaris Tar. irregularis (x 1000) 142

Figs. 2-3. Kirchneriella obesa (x 1000) 142

Fig. 4. Eirchneriella o&eso var. major (x 1000) 142

Figs. 5-6. Eirchneriella obesa var. aperta (x 1000) 143

Fig. 7. Eirchneriella contorta (x 1000) 143

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BULLETIN 57, PLATE 36

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PLATE 36.

Page

Figs. 1-2. Kirchneriella elongata (x 1000) 143

Fig. 3. Crucigenia rectangularis (x 1000) 144

Figs. 4-5. Crucigenia irregularis (x 1000) 145

Fig. 6. Crucigenia crucifera (x 1000) 145

Figs. 7-9. Crucigenia truncata (x 1000) 146

Figs. 10-14. Crucigenia quadrata (x 1000) 147

222 WISCONSIN PETTOPLANKTGN

PLATE 37.

Page

Fig. 1. Crucigenia apiculata (x 1000) 146

Fig. 2. Crucigenia tetrapedia (x 1000) 147

Fig. 3. Crucigenia fenstrata (x 1000) 148

•Fig. 4. Crucigenia Lauterbornei (x 1000) 148

Figs. 5-6. Tetrastrum staurogeniaclorme, (x 1000) 149

Figs. 7-11. Tetradesmus wisconsinensis (x 1000) 150

Figs. 12-14. Scenedesmus obliquus (x 1000) Ibl

Figs. 15-17. Scenedesmus dimorphus (x 1000) 151

Figs. 18-20. Scenedesmus bijuga (x 1000) 152

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BULLETIN 57, PLATE 37

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BULLETIN 57, PLATE 38

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PLATE 38.

Page

Figs. 1-4. Scenedesmus acuminatus (x 1000) 152

Figs. 5-9. Scenedesmus Bernardii (x 1000) .. 352

Figs. 10-11. Scenedesmus bijuga var. alternans (x 1000) 153

Figs. 12-14. Scenedesmus arcuatus (x 1000) 153

Figs. 15-16. Scenedesmus arcuatus var. capitatus (x 1000) 153

224 WISCONSIN PHYTOPLA.NKTON

PLATE 39.

Page

Figs. 1-3. Scenedesmus arcuatus var. platydisca (x 1000) 154

Figs. 4-6. Scenedesmus acutiformis (x 1000) 154

Figs. 7-10. Scenedesmus armatus (x 1000) 154

Fig. 11. Scenedesmus armatus var. major (x 1000) 155

Figs. 12-14. Scenedesmus brasiliensis (x 1000) 155

Figs. 15-16. Scenedesmus hystrix (x 1000) 155

Figs. 17-19. Scenedesmus denticulatus (x 1000) 155

Figs. 20-22. Scenedesmus longus (x 1000) 156

Figs. 23-25. Scenedesmus al)undans (x 1000) 157

Figs. 26-27. Scenedesmus abundans var. longicauda (x 1000) 157

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PLATE 40.

Figs.
Figs.
Figs.
Figs.
Figs.
Figs.
Fig.

1-2. Scenedesmus longus var. .
3-5. Scenedesmus abundans va
6-8. Scenedesmus abundans va
9-11. Scenedesmus quadricauda
12-14. Scenedesmus quadricauda
15-16. Scenedesmus quadricauda
17. Scenedesmus quadricauda

15

Naegelii (x 1000)

Page
156

,r. ftrevicaitda (x 1000)

157

r. asymmetrica (x 1000)

157

(x 1000)

15S

var. longispina (x 1000)

159

var. quadrispina (x 1000)

158

var. parvus (x 1000)

158

226 WISCONSIN PHYTOPLANETON

PLATE 41.

Page

Figs. 1-2. Scenedesmus quadricauda var. maximus (x 1000) 159

Figs. 3-7. Scenedesmus quadricauda var. Westii (x 1000) 159

Figs. 8-11. Scenedesmus opoliensis (x 1000) 159

Figs. 12-13. Coelastrum microporum (x 825) 160

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BULLETIN 57, PLATE 42

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PLATE 42.

Page

Fig. 1. Coelastrum microporum (x 825) 160

Figs. 2-3. Coelastrum cambricum (x 825) 161

Figs. 4-6. Ooelastrum reticulatum (x 825) 161

Figs. 7-8. Coelastrum proboscideum (x 825) 162

228 WISCONSIN PHYTOPLANKTON

PLATE 43.

Page

Figs. 1-2. Coelastrum proboscidcum (x 825) 162

Figs. 3-5. Actinastrum gracillimum (x 1000) 164

Figs. 6-7. Actinastrum HantzscJii (Fig. 6, x 500; fig. 7, x 1000) 164

Fig. 8. Actinastrum HantzscJii var. elongatum (x 1000) 165

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BULLETIN 57, PLATE 43

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BULLETIN 57, PLATE 44

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WISCONSIN PHYTOPLA.NKTON 229

PLATE 44.

Page

Fig. 1. Sorastrum americanum (x 1000) 163

Figs. 2-3. Sorastrum americanum var. undulatum (x 1000) 163

Figs. 4-5. Sorastrum spinulosum (x 1000) 163

Fig. 6. Hydrodictyon reticulatum (x 100) 166

230 VS1SCONSIN PEYTOPLANETON

PLATE 45.

Page

Fig. 1. Eydrodictyon reticulatum (x 266) 166

Figs. 2-6. Pediastrum simplex var. duodenarium (x 333) 167

Fig. 7. Pediastrum integrum (x 333) 168

Figs. 8-10. Pediastrum integrum var. priva (x 666) 168

Fig. 11. Pediastrum araneosum (x 333) 168

Figs. 12-13. Pediastrum araneosum var. rugulosum (Fig 12, x 333,

fig. 13, x 666) 168

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BULLETIN 57, PLATE 45

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BULLETIN 57, PLATE 46

14

17

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WISCONSIN PHYTOPLANKTON 231

PLATE 46.

Page

Fig. 1. Pediastrum sculptatum (x 333) 169

Figs. 2-7. Pediastrum Boryanum (x 333) 169

Fig. 8. Pediastrum Boryanum var. undulatum (x 333) 170

Fig. 9. Pediastrum Boryanum var. longicorne (x 333) 170

Figs. 10-13. Pediastrum Kawraiskyi (x 33S> 170

Figs. 14-16. Pediastrum duplex (x 333) 171

Fig. 17. Pediastrum duplex var. rolundatum (x 333) 172

232 WISCONSIN PHYTOPLANKTON

PLATE 47.

Page

Figs. 1-3. Pediastrum duplex var. clathratum (x 333) 171

Figs. 4-7. Pediastrum duplex var. reticulatum (x 333) 172

Figs. 8-11. Pediastrum duplex var. gracillimum (x 333) 172

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BULLETIN 57. PLATE 47

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BULLETIN 57, PLATE 48

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WISCONSIN PHYTOPLA.NKTON 233

PLATE 43.

Page

Figs. 1-2. Pediastrum duplex var. gracillimum (x 333) , 172

Figs. 3-4. Pediastrum duplex var. cohaerens (x 333) 173

Figs. 5-8. Pediastrum biradiatum (x 333) 173

Figs. 9-12. Pediastrum tetras (x 666) 173

Figs. 13-14. Pediastrum tetras var. tetraodon (x 666) 174

234 WISCONSIN PHYTOPLANETON

PLATE 49.

Page

Figs. 1-2. Pediastrum tetras var. tetraodon (x 1000) 174

Fig. 3. Eaustropsis RicJiteri (x 1000) 175

Figs. 4-7. Characium stipitatum (x 1000) 176

Figs. 8-15. Characium curvatum (x 1000) 176

Figs. 16-19. Characium cylindricum (Fig. 16, x 400; figs. 17-19, x

1000) 177

Figs. 20-24. Characium gracilipes (x 1000) 178

Figs. 25-29. Characium limneticum (x 1000) 177

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BULLETIN 57, PLATE 49

29

20

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BULLETIN 57, PLATE SO

'

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WISCONSIN PHJTOPLANETON 235

PLATE 50.

Page

Figs. 1-3. Cladophora glomerata (Figs. 1-2, x 50, fig. 3, x 300) 182

Figs. 4-5. Ulothrix subconstricta (x 1000) 179

Fig. 6. Ulothrix zonata (x 400) 179

Fig. 7. Stigeoclonium lubricum (x 300) 180

Fig. 8. AphanocJiaete vermiculoides (x 400) 181

236 WISCONSIN PHYTOPLANKTON

PLATE 51.

Page

Fig. 1. Mougeotia viridis (x 400) 184

Fig. 2. Zygnema pec-tinatum (x 400) 185

Fig. 3. Spirogyra porticalis (x 400) .... 185

WISCONSIN SURVEY

BULLETIN 57, PLATE 51

SMITH — ALGAE

COCKAYNE. BOSTON

INDEX

Page

Acanthococcus reticularis Reinsch... 109
ACANTHOSPHAERA Lemm ........ 128

A. ZACHARIASI Lemm. pi. 29, f. 6-8. . 128
ACTINASTRUM Lag ............... 164

A. GRACILLIMUM G. M. Smith pi.

43, f. 3-5 ....................... 164

A. HANTZSCHI Lag. pi. J,S, f. 6-7 ---- 164

v. ELONGATUM G. M. Smith pi. 43,

f. S ............................. 165

AKONTAE ........................ 188

ANABAENA Bory ................. 55

A. AFPINIS Lemm. pi. 8, f. 7 ........ 57

A. AUGSTUMALIS v. MARCHICA

Lemm. pi. S, f. 9-10 ............. 58

A. BORNETIANA Collins pi. 8, f. S. . 58
A. CIRCINALIS (Ktz.) Rab. pi. 9,

f. 4-5 ........................... 59

v. MACROSPORA (Wittr.) de Toni

pi. 9, f. 6; pi. 10, f. 1 ............ 60

A.FLOS-AQUAE (Lyng.) Breb. pi. 10,

f. 2-4 ........................... 60

A. flos-aquae Klebh. non (Lyng.)

Breb ........................... 61

v. TRELEASII Born. & Flah. pi. 10,

f. 5-7 ........................... 60

A.Hassallil (Ktz.) Wittr ........... 59

v. macrospora Wittr .............. 60

A. LEMMERMANNI P. Richt. pi. 10,

A. LEVANDERI Lemm. pi. 8, f. 4-5. . 58
A. LIMNETICA G. M. Smith pi. 8, f. 8 57
A. MACROSPORA v. ROBUSTA

Lemm. pi. 8, f. 6 ................ 57

A. mendotae Trelease ............... 60

A. PLANCTONICA Brunnth. pi. 8, f. 2 56
A. SPIROIDES v. CRASSA Lemm.

pi. 9, f. 1-S ..................... 59

Anacystis pulverus Wood ........... 40

ANKISTRODESMUS Corda ........ 134

A. Chodati (Tanner-Fullmant

' Brunnth ....................... 138

A. FALCATUS (Corda) Ralfs

pi. 32, f. J ....................... 134

v. ACICULARIS (A. Br.)

G. S. West .................. 135

v. MIRABILIS (W & G. S. West)
G. S. West pi. 32, f. 3 — 5 ....... 135

v. spiralis (Turn.) G. S. West.. 135

v. TUMIDUS (W. & G. S. West)
G. S. West pi. 32, f. 2 .......... 135

Page

A. lacustre (Chodat) Ostenfeld 139

A. longissimum v. septatum

(Chodat) Brunnth 177

A. Pfitzeri (Schrod.) G. S. West 138

A. SPIRALIS (Turn.) Lemm.

pi. 32, f. 6 — 7 135

APHANIZOMENON Morren 61

A. FLOS-AQUAE (L.) Ralfs

pi. 11, f. 2—4 61

APHANOCHAETACEAE 181

APHANOCHAETE A. Br 181

A. VERMICULOIDES Wolle

pi. 50, f. 8 181

APHANOCAPSA Nag 41

A. DELICATISSIMA W. &. G. S.

West pi. 2, f . 7 41

A. ELACHISTA v. CONFERTA

W. & G. S. West pi. 2, f. S 42

v. PLANCTONICA G. M.

Smith pi. 3, f. 3 42

| A. ENDOPHYTICA G. M. Smith

pi. 2, f. 10 42

A. GREVILLEI (Haas.) Rab.

pi. 3, f. 1 43

A. PTJLCHRA (Ktz.) Rab. pi. 2, f. 9. 42
A. RIVULARIS (Carm.) Rab.

pi. 3, f. 2 43

APHANOTHECE Nag 4?

A. CLATHRATA W. & G. S. West

pi. b', f. 3 44

A. NIDULANS P. Richt. pi. 6, f. 1. . . 44

v. ENDOPHYTICA W. & G. S.

West pi. 5, f. 6 44

A. PRASINA A. Br. pi. 5, f. 5 45

I A. STAGNINA (Spreng.) A. Br.

pi. 6, f. 2 45

ASTEROCOCCUS Scherffel 103

A. LIMNETICUS G. M. Smith

pi. 20, f. 7— 10 104

Autocolony 1°9

AUTOSFORACEAE 109

Autospore

BOTRYOCOCCACEAE

BOTRYOCOCCUS Ktz

B. BRAUNII Ktz. pi. 15, f. 5

B. Braunii G. S. West non Ktz 83

B. PROTUBERANS v. MINOR

G. M. Smith pi. 15, f. 6 — 7 85

B. SUDETICUS Lemm. pi. 15, f. 8 83

CARTERIA Diesing 92

238

INDEX

Page
C. CORDIFORMIS (Carter) Diesing

pi. 16, f. 1 92

C. KLEBSII (Dang.) Dill

pi. 16, f. 2—4 93

CARTERIACEAE 92

CHAETOPHORACEAE 180

CHARACIUM A. Br 175

C. CURVATUM G. M. Smith

pi. 49, f. 8— 15 176

C. CYLINDRICUM Lamb.

pi. 49, f. 16—19 177

C. GRACILIPES Lamb. pi. 49, t. 20 — 84 178
C. LIMNETICUM Lemm.

pi. 49, f. 25—29 177

C. STIPITATUM (Bachman) Wille

pi. 49, f. 4—7 176

CHLAMYDOMONADACEAE 90

CHLAMYDOMONAS Ehr 90

C. communis Snow 91

C. DINOBRYONI G. M. Smith

pi. 16, f. 5 — 7 91

C. EPIPHYTICA G. M. Smith

pi. 16, f. 11 — 13 91

C. GLOBOSA Snow pi. 16, f. 8 90

C. SNOWII Printz pi. 16, f. 9—10. ... 91

CHLORAMOEBACEAE 79

CHLORELLA Beyerinck 108

C. VULGARIS Beyerinck pi. 22, f. 1.. . 108

CHLOROBOTRYDACEAE 82

CHLOROBOTRYS Bohlin 82

C. LIMNETICUS G. M. Smith

pl. 15, f. 9 82

C. REGULARIS (W. West) Bohlin

pl. 15, f. 10 82 ;

CHLOROCHROMONAS Lewis 80

C. MINUTA Lewis pl. 15, f. 1 — 3 80

Chlorococcus regulare W West 82

CHLOROPHYCEAE 88

CHLOROSACCACEAE 81

Chodatella ciliata (Lag.) Lemm 129

v. minor G. M. Smith 129

C. citriformis Snow 130

C. Droescheri Lemm 131

C. longiseta Lemm 130

C. subsala Lemm 130

CHROMULINALES 66 j

CHROOCOCCACEAE 27

CHROOCOCCUS Nag 27

C. DISPERSUS (v. Keiss.) Lemm.

pl. 1, f. 2 28

v. MINOR G. M. Smith pl. 1, f. S. 28

C. GIGANTEUS W. West, pl. 2, f. 1. .. 30

C. LIMNETICUS Lemm. pl. 1, f . 4. ... 29
v. CARNEUS (Chod.) Lemm.

pl. 1, t. 6 30

v. DISTANS G. M. Smith

pl. J, f. 7 30

v. ELEGANS G. M. Smith

pl. 1, f. 8 30

v. SUBSALSUS Lemm. pl. l,t. 5. 29
Chroococcnis minor var dispersus

v. Keiss. 28

Page

C. MINUTUS (Ktz.) Nag. pl. i, t. 1. .. 28
C. TURGIDUS (Ktz.) Nag. pl. i, f. 9. 3!

! CHRYS AMOEBA Klebs 67

| C. RADIANS Klebs pl. 12, t. 1. .. '. 67

i CHRYSIDASTRUM Lauterborn 78

I C. CATENTATUM Lauterborn

pl. 14, f. 7—8 7g

CHRYSOMONADINEAE '.'.', 65

; CHRYSOSPHAERELLA Lauterborn 69
! C. LONGISPINA Lauterborn

pl. 12, t. 7 — 8 69

' CLADOPHORA Ktz '.'. i82

|C. GLOMERATA (L.) Ktz.

pl. 50, t. 1 — S 182

CLADOPHORACEAE '. ' ' ' 132

i Clathrocystis aeruginosa (Ktz.)

Henfrey 39

CLOSTERIOPSIS Lemm. .......... 135

C. LONGISSIMA v. TROPICA W.

& G. S. West pl 32, f. 8 136

COCCOGONEALES 26

COCCOMYXA Schmidle 139

COELASTREAE IQQ

COELASTRUM Nag. .........'..'.'.'. 160

| C. CAMBRICUM Arch. pl. 42, f. 2—3. 161

j C. compositum G. S. West 162

' C. MICROPORUM Nag. pl. 41, f.

12—13; pl. 42, f. 1 ' 160

C. PROBOSCIDEUM Bohlin pl. 42, f.

7—8; pl. 43, f. 1— 2 ' . .' 162

| C. RETICULATUM (Dang.) Senn

pl. 42, t. 4—6 161

COELOSPHAERIUM Nag 3j

C. DUBIUM Grunow pl. 3, f. 7. . ! . "
C. KUETZINGIANUM Nag,

pl. S, t. 4—5 34

C. NAEGELIANUM Unger

Pl. 3, f. 6; pl. 4, f. i 35

Coenocyte gg

Cohniella staurogeniae forme SchrOder 149

Collection methods 10

Conferva echinulata J. E. Smith 63

CONJUGALES ig3

CRUCIGENIA Morren 144

C. APICULATA (Lemm.) Schmidle

Pl. Sn, f- 1 146

C. CRUCIFERA (Wolle) Collins

pl. S6, f. 6 145

C. FENESTRATA Schmidle pl. 37, f. 3. 148
C. IRREGULARIS Wille pl. 36, f. 4—5. 145
C. LAUTERBORNEI Schmidle

Pl. 87, f. 4 148

C. QUADRAT A Morren pl. 36, f. 10 — 14. 147

v. punctata (Schmidle) 147

C. RECTANGULARIS (Nag.) Gay

pl. 36, f. S 144

C. TETRAPEDIA (Kirchner) W & G.

S. West pl. 37, f. 2 147

C. triangularis (Chodat) Schmidle. . . . 147
C. TRUNCATA G. M| Smith

pl. 36, f. 7 — 9 146

CRUCIGENIEAE . . 143

INDEX

239

Page:

DACTYLOCOCCOPSIS Hansg 47 !

D. ACICULARIS Lemm. pi. 6, t. 8 — 10 48
D. RHAFHIDIOIDES Hansg.

pi. 6, f. 7 47

DICTYOSPHAERIACEAE 104

DICTYOSPHAERIUM Nag 104

D. EHRENBERGIANUM Nag.

pi. SO, f. 11 — 12 105

D. PULCHELLUM Wood pi. 20,

f. IS; pi. n, t. 1 105

DIMORPHOCOCCUS A. Br 106

D. LUNATUS A. Br. pi. 21, f, 5 106 !

DINOBRYON Ehr 72 i

D. BAVARICUM Imhof pi. IS, f. 10. . . 73 ;
D. CALJCIFORME Bachm.

pi. 13, f. 5 — 6 73

D. DIVERGENS Imhof pi. if, f. 2 75

D. SETULARIA Ehr. pi. IS, f. IS;

pi. 14, t. 1 74

D. SOCIALE Ehr. pi. IS, f. IS 74

D. STIPTTATUM Stein pi. IS, f . 11. . . . 74
D. TABELLARIAE (Lemm.) Pascher

pi. 13, i. 7 — 9 73

D. utriculus var. tabellariae Lemm. . . 73

DINOBRYONACEAE 72

ECHINOSPHAERELLA G. M. Smith 128

E. LIMNETICA G. M. Smith

pi. 29, f. 9 — 11 128

ECHINOSPHAERIDIUM Lemm 128

ELAKTOTHRIX Wille 139

E. GELATINOSA Wille pi. 34, f. 1 — 3 139
E.VIRDIS (Snow) Printz pi. SS, f. 7. 140

EUASTROPSIS Lag 174 ;

E. RICHTERI (Schmidle) Lag.

pi. 1,9, f. 3 175

Euastrum tetraodon Corda 174

EUCHROMULINACEAE C6

EUCHRYSOMONADINAE 66

EUDORINA Ehr 95

E. ELEGANS Ehr. pi. 19, f. 1 96

EUHYMENOMONADACEAE 70

Euplankton 1

Facultative plankton 1

FRANCEIA Lemm 131

F. OVALIS (France) Lemm. pi. SI, f. k 131

Fusola virdis Snow 140

Gas vacuoles 33

Geography of Wisconsin 5

Geology of Wisconsin 5

GLOEOCOCCUS 102

GLOEOCYSTIS Nag 100

G. GIGAS (Ktz.) Lag. pi. 19, f. 2 101

GLOEOCYSTOPSIS G. M. Smith 102

G. LIMNETICUS G. M. Smith

pi. 20, t. 1 — 2 103

GLOEOTHECE Nag 45

G. LINEARIS Nag. pi. 6, f. 5 46

v. COMPOSITA G. M. Smith

pi. 6, f. 6 46

GLOEOTAENIUM Hansg 115

G. LOITLESBERGERIANUM Hansg.

pi. 23, f. 8 — 9 115

Page

GLOEOTRICHIA J. G. Ag 63

G. ECHINULATA (J. E. Smith) P.

Richt. pi. 11, f. 5 — 6 63

G. pisum Born, et Flah. non Thur. ... 63

GOLENKINIA Chodat 127

G. PAUCISPINA W. & G. S. West

pi. 29, f. If— 5 127

G. RADIATA Chodat pi. 29, f. 2 — 3. . . 127

GOMPHOSPHAERIA Ktz 36

G. AFONINA Ktz. pi. 4, f. 2— S 37

v. CORDIFORMIS Wolle pi. 4, f. 1, 37

G. LACUSTRIS Chodat pi. I,, f. 5 36

G.Naegeliana (Unger) Lemm 35

GONIUM Mueller 94

G. FECTORALE Mueller

pi. 16, f. 14 — 15 94

Heleoplankton 5

Herposteiron hyalothecae Hansg 181

HETEROCHLORIDALES 79

HETEROCOCCALES 80

Hormogones 26

HETEROKONTAE 79

HETEROTRICHALES 86

KORMOGONEALES 43

Hormogones 48

HYALOBRYON Lauterborn 75

H. Lauterbornei var mucicola Lemm. 75
M. MUCICOLA (Lemm.) Pascher

pi. Ik, t. S — 4. 75

, HYDRODICTYACEAE 165

HYDRODICTYON Roth 165

H. RETICULATUM (L.) Lag.

pi. M, f- 6; pi. 45, f. 1 166

i HYDRURINEAE 76

Ineffiffiata neglecta W. & G. S. West 84

| TSOCHRYSIDALES 69

' ISOKONTAE 88

Key to the genera 21

! KIRCHNERIELLA Schmidle 140

I K. aperta Teiling 143

jK. CONTORT A (Schmidle) Bohlin

pi. 35, f. 7 143

i K. ELONGATA G. M. Smith

pi. 36, f. 1 — 2 143

K. LUNARIS (Kirchner) Mobius

pi. 34, f. 4 141

v. DIANAS Bohlin pi. 34, f . 5. ... 141
v. IRREGULARIS G. M. Smith

pi. 35, f. 1 142

K. OBESA (W. West) Schmidle

pi. 35, f. 2—3 142

v. APERTA (Teiling) Brunnthaler

pi. 35, f. 5 — 6 143

v. contorta Schmidle 143

v. MAJOR (Bernard) G. M.

Smith pi. 35, f. 4 142

LAGERHEIMIA Chodat 129

L. CILIATA (Lag.) Chodat

pi. SI, f. 1—S 129

v. MINOR G. M. Smith pi. SI, (. S. 129
L, CITRIFORMIS (Snow) G. M.

Smith pi. SO, f. 1— 8 130

240

INDEX

Page
L. DROESCHERI (Lemm.) Printz

pL SO, f. 5—f 131

L.LONGISETA (Lemm.) Printz

pi. 30, f. 8 — 9 130

v. MAJOR G. M. Smith

pi. 30, f. 10 — 12 130

L. SUBSALSA Lemm. pi. SO, f. 3— 4. . . 130

Lake areas of Wisconsin 6

Lakes

Altitude 6

Chemical composition of water . . 8

Formation of Wisconsin Lakes . . 5

Hard water 7

Medium water 7

Origin of Names 11

Size 5

Soft water 7

Temperature 6

Lemmermannia emarginata

(Schriider) Chodat 147

Lemmermannia tetrapedia (Kirch-

ner) Lemm 148

List of Lakes studied 13-19

•LTNGBYA C. A. Ag 52

L. BIRGEI G. M. Smith pi. 7, f. 1.', — J.7. 54

L. CONTORTA Lemm. pi. 7, f. 12 — 13. 53

L. LIMNETICA Lemm. pi. 7, f. 9— 11. 52

L. Wollei Farlow 54

L. Wollei Treleasfe non Farlow 54

MALLOMONADACEAE 67

MALLOMONAS Perty 67

M. ALPINA Pascher & Ruttner

pi. 12, f. .', 68

M. CAUDATA Iwanoff pi. 12, f . 6. . . . 69
M. PRODUCTA ( Zach. ) Iwanoff

pi. 12, f. 2 68

v. MARCHICA Lemm. pi. 12, f. 3. 68

M. TONSURATA Telling pi. 12, f . 5. . . 68

MERISMOPEDIA Meyen 31

M. ELEGANS A. Br. pi. 2, f. 5 32

v. MAJOR G. M. Smith pi. 2, f. 6. 32

M. GLAUCA (Ehr. I Nag. pi. 2, f. 4 :',2

M. PUNCTATA Meyen pi. 2, f. 3 33 I

M. TENUISSIMA Lemm. pi. 2, t. 2. . . 33 |

MICRACTINIEAE 125

MICRACTINIUM Fresenius 125

M. PUSILLUM Fresenius

pi. 28, f. 1—3 125

v. ELEGANS G. M. Smith

pi. 29, f. 1 126

M. QUADRISETUM (Lemm.) G. M.

Smith pi. 28, f. 4 126

MICROCTSTIS Ktz 38

M. AERUGINOSA Ktz. pi. 5, f. 2—3. 39
v. MAJOR (Wittr.) G. M. Smith

pi. .',, f. 6 40

M.FLOS-AQUAE (Wittr.) Kirchner

pi. 5, f. 1 39

M. ICHTHTOBLABE Ktz 38

M. INCERTA Lemm. pi. 5, f. 4 40

M. PULVERA (Wood) Migula 40

Monactinus duodenarius Bailey 167

Page

M. octonarius Bailey 167

MOUGEOTIA C. A. Ag 184

M. VIRIDIS (Ktz.) Wittr. pi. 51, f. 1. 184
Myxonema lubricur.i (Dillw.) Fries... 180

MYXOPHYCEAE 26

OCHROMONADACEAE 71

OCHROMONADALES 70

OOCYSTEAE 110

Oocy Stella Lemm 114

OOCYSTIS Nag 110

O. BORGEI Snow pi. 22, t. !, Ill

O. ciliata Lag 129

O. CRASSA Wittr. pi. 22, f. 12— IS 113

O. ELLIPTICA W. West pi. 22, f. 5. . . Ill
O. EREMOSPHAERIA G. M. Smith

pi. 23, f . 1-2 113

O. GLOEOCYSTIFORMIS Borge pi. 22,

f. 7 112

O. LACUSTRIS Chodat pi. 22, f. 8 — 9. 112
O. NATANS v. MAJOR G. M. Smith

pi. 23, f. 4-5 114

O. FANDURIFORMIS v. MINOR G.

M. Smith pi. IS, f. S 114

O. PARVA W. & G. S. West pi. 22, f. 6 112

O. PUSILLA Hansg. pi. 22, f. S Ill

O. SOLITARIA Wittr. pi. 22, f. 11 113

O. SUBMARINA Lag. pi. 22, f. 10 113

OPHIOCYTIACEAE 85

OPHIOCYTIUM Nag 85.

O. CAP1TATUM Wolle pi. 15, f. 1S-1S . 86
v. LONGISPINUM (Mobius) Lemm.

pi. 15, f. 14-16 86

O. PARVULUM (Perty) A. Br. pi. 15,

f. 11 86

OSCILLATORIA Vaucher 50

O. PROLIFICA (Grev.) Gom. pi. 7,

f. 3-5 51

O. RUBESCENS D. C 51

O. TENTHS C. A. Ag. pi. 7, f. 6 52

v. TERGESTINA (Ktz.) Rab. pi. 7,

f. 7-8 52

OSCILLATORIACEAE 49

PALMELLACEAE 100

PANDORINA Bory 95

P. MORUM Bory pi. 16, f. 16-17 95

PEDIASTRUM Meyen 166

P. ARANEOSUM Racib. pi. 45, f. 11.. 168
v. RUGULOSUM (G. S. West) G. M.

Smith pi. 45, f. 12-13 168

P. BIRADIATUM Meyen pi. 1,8, f. 5-8 173
P. BORYANUM (Turp.) Menegh. pi.

46, f. 2-7 169

v. LONGICORNE Racib. pi. >,6, f. 9. 170
v. longicorne forma glabrum Racib. 170
v. longicorne forma granulatum

Racib 170

v. UNDULATUM Wille pi. 46, f. 8. . 170

P. DUPLEX Meyen pi. 46, f. H-16 171

v. CLATHRATUM (A. Br.) Lag.

pi. 47, t. 1-S 171

v. COHAERENS Bohlin pi. tf, t. t-4 17J

INDEX

24J

Page
v. GRACILLIMUM W. & G. S. West

pi. W, t. 8-11; pi. 48, f. 1-2 172

v. RETICULATUM Lag. pi. 47, f. 4-7 172
v. reticulatum forma cohaerens

(Bohl.) Brunnth 173

v. ROTUND ATUM Lucks pi. 46, t. n 172

P. INTEGRUM Nag. pi. 45, f. 7 168

v. PRIVA Printz pi. J,5, f. 8-10 168

P.rotula (Ehr.) A. Br 173

P. SCULPTATUM G. M. Smith pi. 46,

f. 1 169

P. SIMPLEX v. DUODENARIUM

(Bailey) Rab. pi. 45, f. 2-6 167

v. clathratum (Schroter) G. S. West 167
P. TETRAS (Ehr.) Ralfs pi. 48, t. 9-12 173

v. OBTUSATA Racib 174

v. TETRAODON (Corda) Hansg.

pi. 48, f. 13-14 ; pi. 49, f. 1-2 174

PERONIELLA Gobi 81

P. PLANCTONICA G. M. Smith pi.

15, f. 4 81

PHAEOCAPSACEAE 76

PHAEOCAPSALES 76 '

PHAEOCOCCUS Borzi 76

P. FLANCTONICUS W. & G. S. West

pi, 14, f. 5 76

PHAEOPHTCEAE 65

Phythelois ovalis France 131

Fhytoplankton 1 |

Pithiscus Klebsii Dangeard 93 |

PLANKTOSPHAERIA G. M. Smith.. 103
P. GELATINOSA G. M. Smith pi. SO,

t. 3-6 103

FLANOSPORACEAE 175 :

PLECTONEMA WOLLEI Farlow 54 -

PLEODORINA Shaw 96 i

P. CALIFORNICA Shaw pi. n, t. 1-3 97 ;

Polycystis ichtliyoblabe Ktz 38

POLYEDRIOPSIS Schmidle 124

P. SPINULOSA Schmidle pi. 27, f. 7-8 124 |

Polyedrnim gracile Reinsch 122 '

P. hastatum var. palatinum Schmidle 121 !

P. lobulatum Nag 122

P. muticum v. punctulatum Reinsch. . 116 '

P. tetraedricum Nag 118

v. hastatum Reinsch 121 j

P. trigonum Nag 117

v. gracile Reinsch 117 |

v. setigerum (Arch.) Schroder 117

PROTOCOCCACEAE 108 '

FROTOCOCCALES 99 |

Protococcus minutus Ktz 28

Pseudocilia 102

Pseudovacuoles 33

Pyrenoids 88

QUADRIGULA Printz 137

Q. CHODATI (Tanner-Fullman) G.

M. Smith pi. SI, f. 3 138

Q. LACUSTRIS (Chodat) G. M.

Smith pi. SS, t. 4-6 139

Q. PFITZERI (Schroder) G. M.

Smith pi. S3, t. 1-2 1S8 ;

Page

Relative abundance of different species 28
RHABDODERMA Schmidle & Lauter-

born 4g

R. LINEARE Schmidle & Lauterborn

Pi. 6, t. 4 47

Rhaphidium Braunii var. lacustre

Chodat 139

: R. Chodati Tanner-Fullman 188

i R. longissimum var. septatum Chodat 177

v. tropicum W. & G. S. West 136

i R. Pfitzeri Schroder 1S8

\ R. spirals Turner 135

1 RHIZOCHRTSIDINAE 77

RHIZOCHRTSIS Pascher 77

R. LIMNETICA G. M. Smith pi. 14, f.G 77

R. PLANCTONICA Pascher 78

Richteriella botryoides (Schmidle)

Lemm 125

forma fenestrata Chodat 125

forma tetraedrica Lemm 126

1 Rivularia echinulata J. E. Smith G!

RIVULARIACEAE 62

SCENEDBSMUS Meyen 150

S. ABUNDANS (Kirchner) Chodat pi.

Sf>, f. 25-25 157

v. ASTMMETRICA (Schro'der) G.

M. Smith pi. 40, f. 6-8 157

v. BREVICAUDA G. M. Smith pi.

40, f. S-5 157

v. LONGICAUDA G. M. Smith pi.

89, f. 26-27 157

S. ACUMINATUS (Lag.) Chodat pi.

38, f. 1-4 152

S. ACUTIFORMIS SchrOder pi. 39, f.

4-6 154

S. alternans Reinsch 158

S. ARCUATUS Lemm. pi. 38, f. 12-14. • 153
v. CAPITATUS G. M. Smith pi. 38,

f. 15-16 15J

v. PLATYDISCA G. M. Smith pi. S9,

f. 1-3 154

S. ARMATUS (Chodat) G. M. Smith

pi. 39, f. 7-10 154

v.MAJOR G. M. Smith pi. 39, f. 11. . 155
S. BERNARDII G. M. Smith pi. 38, f.

5-9 152

S. BIJUGA (Turpin) Lag. pi. 37, f.

18-20 152

v. ALTERNANS (Reinsch) Borge

pl. .'58, f. 10-11 15J

S. bijugatus (Turpin) Ktz 152

S. BRASILIENSIS Bohlin pi. 3!), f.

1&-14 155

S. caudatus Nag. non Corda 15S

S. DENTICULATUS Lag. pi. 39, f.

17-19 155

S. DIMORPHUS (Turpin) Ktz. pi. 37,

f. 15-17 151

S. HYSTRIX Lag. pi. 39, f. 15-16 155

S. LONGUS Meyen pi. 39, f. SO-29 156

v. NAEGELII (Breb.) G. M. Smith

pi. 40, f. 1-3 156

242

INDEX

Page'

8. Naegelii Breb 156

S. OBLIQUUS (Turpin) Ktz. pi. 57,

f. 12-14 151

S. OPOLJENSIS P. Richter pi. 41, t.

8-11 159

S. QUADRICAUDA (Turpin) Breb.

pi. 40, t. 9-11 158

v. abundans (Kirchner) Lag 157

v. asymmetrica SchrOder 157

v. LONGISPINA (Chodat) G. M.

Smith pi. 40, t. 1S-14 159

v. MAXIMUS W. & G. S. West pi.

41, f. 1-2 159

v. PARVUS G. M. Smith pi. W, f. 17 158
v. QUADRISPINA (Chodat) G. M.

Smith pi. 40. t. 15-16 158

v. setosus ( Kirchner > Lag 156

v. WESTII G. M. Smith pi. 41, t.

3-7 159

SCHROEDERIA Lemm 136

S. JUDAYI G. M. Smith pi. 32, f. 9-11 137
S. SETIGERA (SchrOder) Lemm. pi.

32, f . 12 137

SELENASTREAE 132

SELENASTRUM Reinsch 132

8. acuminatum G. S. West non Lag. 133

S. acuminatum Lag 152

S. BIBRAIANUM Reinsch

pi. 37, f. 6—7 133

S. GRACILE Reinsch pi. SI, f. 5 133

S. WESTII G. M. Smith pi. 81, t. 8 — 10 133
Selenosphaerium americanum Bohlin. 163

Page

TETRADESMUS G. M. Smith 150

T. WISCONSINENSIS G. M. Smith

pi. 37, f. 7 — 11 150

TETRAEDREAE 115

TETRAEDRON Ktz 115

T. arthrodesmiforme v. lobulatum

Wolosz 122

T. CAUDATUM (Corda) Hansg.

pi. 25, t. 4 — 7 120

v. LONGISPINUM Lemm. pi. 25,

f. 8-12 120

T. CONSTRICTUM G. M. Smith

pi. 25, f. 22—24 122

T. ENORME (Ralfs) Hansg. pi. 27, f. 6. 124
T. GRACILE (Reinsch) Hansg.

pi. 25, f. 1—5 122

122

SIPHONOCLADIALES

182

T. HASTATUM (Reinsch) Hansg.

pi. 25, f. 18 121

v. PALATINUM (Schmidle)

Lemm. pi. 25, f. 19— 21 121

T. LIMNETICUM Borge pi 27, f. 1—3. 123
T. LOBULATUM (Nag.) Hansg.

pi. 26, f. 6 — 7

v. POLYFURCATUM G. M.

Smith pi. 26, f. 8 123

T. MINIMUM (A. Br.) Hansg.

pi. 24, f. iO— IS 118

T. MUTICUM v. PUNCTULATUM

(Reinsch) de Toni pi. 23, f. 10—13. 116
T. PENTAERDICUM W. & G. S.

West pi. 25, f. 13— 17 120

v. minimum W. & G. S. West ... 121
T. PLANCTONICUM G. M. Smith

pi. 27, f . 4—5.

123

T. proteiforme G. M. Smith non (Turn.)
Brunnthaler - 117

T. REGULARE Ktz. pi. 24, t. 14.

SORASTRUM Ktz 162

S. AMERICANUM (Bohlin) Schmidle

pi. 44, f. 1 163

UNDULATUM G. M. Smith

pi. 44, f. 2—3 163

S. SPINULOSUM Nag. pi. 44, t. 4—5. 163

SPHAEROCYSTIS Chodat 101

S. SCHOETERI Chodat pi. 19, f. 3—4. 101

SPIROGYRA Link 185

S. PORTICALIS (Mueller) Cleve

pi. 51, f. 3 185

SPIRULINA Turpin 49

S. MAJOR Ktz. pi. 7, f. 1 50

S. PRINCEPS (W. & G. S. West)

G. S. West pi. 7. f. 2 50

Staurogenia apicwloto Lemm 146

8. cruciatum Wolle 145

S. crucifera Wolle 145

S. fenestrata Schmidle 148

S. Lauterbornei Schmidle 148 , 1 25 f i

S. multiseta v. punctata Schmidle ... 147 ' ' p '. o«>iiivi««r

S. tetrapedia Kirchner 147 Tetrapedia emarginata Schrt ^

S. triangularis Chodat 147 I T. pentaedricum Chodat ... •

T. setigera Archer

TETRASPORA Link ]

T. LACUSTRIS Lemm. pi. 19, f. 5 — 6. 1
TETRASTRUM Chodat I49

118
T. regulare Chodat non Ktz ......... -

v. INCUS Telling pi. 24, f. 15— 16. 118
v. TORSUM (Turner) Brunn-

thaler pi. 24, f- n— 1S ......... 119

T. spinulosum Schmidle ............ I24

T. TRIGONUM (Nag.) Hansg.

pi. 23, f. 14—16 ..................

v. GRACILE (Reinsch) de Toni

pi. 24, f . 5—9 ..................

v. SETIGERUM (Archer) Lemm.

pi. 24, f . 1—4 .................

T. VERRUCOSUM G. M. Smith

:

117

117

pi. 25, f . 2—3

119
119

119

147

180

STIGEOCLONIUM Ktz

S. LUBRICUM (Dillwyn) Ktz.

pi. 50, t. 7 180

SYNURA Ehr. , 70

S. UVELLA Ehr. pi. 12, f. 9 — 10.

70

Tetracoccus botry aides W. West 107

T. apiculatum (Lemm.) Brunnthaler.
T. multisetum (Schmidle) Chodat ..

146
.147

INDEX

243

Page
T. STAUROGENIAEFORME

(Schroder) Lemm. pi. SI, f. 5 — 6. 149

TRICHODESMIUM Ehr 54

T. LACUSTRE Klebahn pi. 8, f. 1 64

TRIBONEMA Derbes et Solier 87

T. BOMBYCINA v. DEPAUPERATA

Wille 87

T. MINUS (Wille) Hazen

pi. 15, f. 17—18 87

TRIBONEMACEAE 87

Trichomes 48

TROCHISCIA Ktz

T. RETICULARIS (Reinsch) Hansg

pi. 22, f. 2 109

'.... 178

178

179

Tychoplankton

ULOTRICHACEAE

ULTRICHALES

ULOTHRIX Ktz

U. SUBCONSTRICTA G. S. West

pi. 50, f . IT- 5

U. ZONATA (Weber & Mohr) Ktz.

pi. 50, f. 6

179

179

Page

Uroglena americana Calkins 71

UROGLENOPSIS Lemm 71

U.AMERICANA (Calkins) Lemm.

pi. 18, f. 1—4 71

VOLVOCACEAE 93

VOLVOCALES 89

VOLVOX L 97

V. AUREUS Ehr. pi. 18, f. 2 98

V. GLOBATOR L. pi. 18, f. 3—5 98

V.iMONONAE G. M. Smith, pi. 18, f . 1 99

WESTELLA de Wildeman 106

W. BOTRYOIDES (W. West) de

Wildeman pi. 21, t . 4 ]

v. MAJOR G. M. Smith 107

W. LINEARIS G. M. Smith

pi. 21, f . 2 — S

Zooplankton •

ZYGNEMA C. A. Ag

Z PECTINATUM (Vaucher) C. A.

Ag. pi. 51, f . t ]

ZYGNEMACEAE 183

107

1

184