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INSTITUTED MDCCCXLIV.

LONDON.

MDCCCL.

THE

NATURAL HISTORY

OF THE

BRITISH ENTOMOSTRACA

BY

W. BAIRD, M.D. F.L.S.

LONDON :

I'RINTED FOR THE RA.Y SOCIETY.

MIMTCL.

" Kiliil enim, quod ad Dei immensam gloriam augendum, et ad Natunc mirncula
uperiuuda faciat, rcconditum et abscouditum domcsticis lustrationibus sepclire
debemus."— SCHCEFFEE, Apus Fisciformis, p. 21.

" Full Nature swarms with life ; one wondrous mass
Of animals, or atoms organized.

Where the pool

Stands mantled o'er with green, invisible,
Amid the floating verdure millions stray,"

THOMSON'S Seasons— SUJIIMHT.

' > I I. I "IN 1'KII! I .1" II"! "Ml '* ' ' •

PREFACE.

IN the following pages I have adopted in great part
the general arrangement of M. Milne Edwards, and have
adhered almost exclusively to the terminology used by
him in his classic work on the Crustacea. Some com-
parative anatomists may object to many of the terms
employed as not agreeing with their ideas of Horno-
logies ; but I have preferred using terms sanctioned by
an authority such as M. Milne Edwards, though perhaps
in some cases erroneous, to devising others which might
be liable to the charge of still more serious mistakes.

With few exceptions, the figures of the species of the
Branchiopoda and Lophyropoda have been drawn from
living subjects either by myself or by Mr. Wing, who
has devoted much time and labour in illustrating this
work. Those of the Caligidae and Lerneadoe have been
done by Mr. Wing exclusively, and from specimens
preserved in spirits, most of which have been kindly
placed in my hands for the purpose by W. Thompson,
Esq., of Belfast, to whose liberality I have much pleasure

VI TREFACE.

in bearing testimony, and to whom my best thanks are
due for the assistance afforded me, in enabling me to
describe these curious and interesting parasitical Crus-
taceans. My obligations to the other friends who have
assisted me with specimens or information will be found
gratefully acknowledged in the body of the work.

W. BAIRD.

BAYSWATEU ;
December 1849.

TABLE OF CONTENTS.

PAGE

INTRODUCTION 1

SYSTEMATIC ARRANGEMENT . 9

TABULAR VIEW OF ARRANGEMENT 14

Eutomostraca, Synonyms and Character . 16

Branchiopodd „ ,, . .17

Phyllopoda „ „ . . ib.

Apodidte, Bibliographical History . IS

„ Anatomy and Physiology . 20

\~chiil /(/ike, Bibliographical History . 31

„ Anatomy and Physiology . 33

Branchipodidee, Synonyms and Character . 38

Chirocephaliis, Bibliographical History . 39

„ Anatomy and Physiology . 42

Artemia, Bibliographical History . .55

„ Anatomy and Physiology . 57

( 'ladoci'i'a, Synonyms and Character . 62

lh/p!ini.(id(i', Bibliographical History . ib.

„ Anatomy and Physiology . 69

Polyphemidts, Synonyms and Character .111

Lynceidee, Bibliographical History . 115

,, Anatomy and Physiology . 117

Lophyropoda, Synonyms and Character . 138

Ostracoda „ ,, . ib.

Ci/prididre, Bibliographical History . 139

„ Anatomy and Physiology . . 143

Ci/tlieridee, Synonyms and Character . 162

Cy there, Bibliographical History . 163

„ Anatomy and Physiology . . 164

Cypridinadte, Character . . 176

Copcpoda, Synonyms and Character . 182

Cyclupida, Bibliographical History . 183

„ Anatomy and Physiology . . .186

Diaptomidee, Character . . 218

Cetochilidtc, Synonyms and Character . 233

Ptecilopoda „ „ • 240

' ' Q

.

Vlll CONTENTS.

PAGE

Siphonostoma, Synonyms and Character . 240

Peltocephala, Character . 241

Ari/ulnltc, Bibliographical History . 242

„ Anatomy and Physiology . 246

('f>!i</i(l(/>, Bibliographical History . 257

,, Anatomy and Physiology . 260

l'i//(daridee} Synonyms and Character . . 281

Dinemotifii, Bibliographical History . 282

„ Anatomy . 283

Paitiltn-Hx, Bibliographical History . 286

,, Anatomy . . 287

CecropidfC, Synonyms and Character . 2S9

Cecrops, Bibliographical History . ib.

„ Anatomy and Physiology . 290

L'Chniri/ns, Bibliographical History . 29:i

„ Anatomy, &c. . .-Jill-

Pachycephala, Character . .
Anthosomadfc, Synonyms and Charactri

Anthosoraa, Bibliographical History . ib.

„ Anatomy and Physiology . 29 <

I'li-i/ttxiliitt?, Synonyms and Character . . 29'.)

.\ii-nl lmt>, Bibliographical History . 300

,, Anatomy and Physiology 301

Lerneadte, Bibliographical History .md Systematic Ai-raup -\\\'-\\i . :;o/

„ Anatomy and Physiology . .')Ki

Anchorastomacea, Character . :'rJ.'J

Chond/racanthidae, Bibliographical Ili-inry . ib.

„ Anatomy, &c. . . 32 1

.ltti'/iiii-<i<-«,-j><ri-t'ii, Cliiiractcr . .'131

Lerneopodida, GhKF&eter, &c. • . 3;!-.'

.lit<-lni,;-U,ttl,<\ ('haractcr . . .'l.'Ki

ln, Chararter, &c. . ib.

ii-i'ti, Character . . .'!:is

/',',//•//,///,/'. ( 'haractrr . . :',.')'.)

l.i-i-tifionema, History . ib.

Li-,;ii'uri'i-ti<l,i', Character :,|-.'

l.wit'an-,-,1, Character, \c. . . ib.

,; ;; j (

API-KMHX . . :; id

INDEX . ,'! |'.i

'i.\ \\ - •;:>:>

.— K.- ' iridse n-inl rypri ii \ .,-. p. \.\>.>

NATURAL HISTOEY

BRITISH ENTOMOSTRACA,

INTRODUCTION.

IN this monograph I have retained the name Entomo-
straca, using it to comprehend all those minute Crustaceans
described by Miiller under that name, with the various
additions which have been made since his time by
Latreille, Leach, and others., to that particular group of
curious little animals. To none of the Crustacea has so
little attention been paid by British naturalists as this
division, though there are few deserving of more attentive
study. The exceeding minuteness, and the extreme de-
licacy of structure of the great proportion of them, have
perhaps been the causes of this neglect, deterring most
naturalists from examining and studying them as they
require to be studied — fresh from their native habitats.
The difficulty of preserving them obliges the naturalist to
seek them in their secret lurking-places, the fresh-water
ponds and ditches, and the little pools in the rocks on
the sea-shore, where they are chiefly to be found, or on
the fishes to which they adhere as parasites, and to study
them, as it were, upon the spot, with the aid of his mi-
croscope. The external appearance, however, alone of
many of these interesting little creatures is enough to
excite the curiosity and rouse the attention of the natu-
ralist. Some of them are so like small bivalve shells,

i

~ liUmsil KNTOMOST!! A >

that a person ignorant of the ////Y//;//V////.V \vould not fail
at first sight to call them so ; and the very singular phe-
nomenon of annulose animals being so covered with a
shell, has supplied to Milller the name of Entomostracon,
a term derived from two Greek words signifying "an
insect with a shell."

Previous to the appearance of Midler's work, the feu
species which were known were arranged under one genus,
Monoculus ; and they were so called from their possessing,
or appearing to possess, only one eye. Schceffcr proposed
the name llrat/c/ii/xxl*'* for them, from their feet possessing
branchial appendages; and M filler says he would have pre-
ferred this name to that of Monoculus, were it not that
several genera wanted these organs. The genera, ho\ve\ er,
which he mentions, are the Nauplius and Amymone, and
the Cy there. The two former are only the imperfect young
of the genus Cyclops, and the latter has branchial ap-
pendages attached to the jaws. These facts, however,
he was not aware. of, and therefore he preferred to either
of the above names that of Entomostraca ; a name which
has been retained by almost all succeeding authors.

We find several of these little creatures figured by
some of the earlier writers on natural history, and more
especially by the microscopical observers of the day.
Swammerdam, Rcdi, Leeuwenhoek, Tremblcy, Baker,
Frisch, and .loblot have given figures at least, and some of
them descriptions, of several species, while Schoeffer
has written three separate memoirs upon three different
genera, with minute details, and many illustrative figures.
Linnaeus in 1758 arranged all that were then known
under one genus, Monoculus, except two ; and Geoffrey,
Strom, Goeze, Ilerbst, and DC Geer soon afterwards
added to the number. It is to the celebrated Danish
naturalist, Otho lYedericus Milller, however, that we
are most indebted. To him we owe the collecting
i he \ iinous species already made known into one

* MiilltT.

INTRODUCTION. 3

memoir, the arranging them into distinct genera, many
important and exceedingly interesting details regard-
ing them never before made known, and the addition
of a great number of new species which that zealous
naturalist discovered in the fresh waters and on the sea
coast of Denmark and Norway. He may be called the
first regular historian of these animals. To him it is we
owe a great deal of our knowledge respecting them, and
to his eloquent descriptions is perhaps owing the further
researches and more detailed histories of succeeding writers.
His work on the Entomostraca, published in 1785,*
though it contains several errors which have been pointed
out by later writers, is still one of the most interesting
memoirs in natural history that we are acquainted with.

Since the time of Miiller much has been done by our
continental neighbours to add to our knowledge of these
interesting little creatures, and their individual labours
we shall take particular notice of as we proceed with this
work. It is curious, however, that scarcely any British
naturalist, with the exception of Dr. Leach, has paid the
least attention to the Entomostraca, His memoirs are
scattered over a variety of publications, and a great por-
tion of his attention was directed to the history of the
parasitic animals belonging to the group. It surely is
not from want of interest belonging to them, that the
naturalists of this country have so neglected these curious
little animals, for many of them are worthy of all admira-
tion. "The multifarious and complicated structure of
their body," says Miiller, in his admirable work; "the
wonderful agility of their members ; the very great fine-
ness of their organs ; their singular method of living, and
copulating ; their living in waters which our cattle and we
ourselves are daily drinking; the evils which they may
give rise to, and which are seen to be inflicted upon
fishes ; the advantages, although we are in the greater

* Eiitomostraca, seu iusecta testacea, qme in aquis Daniaj et Norvcgia?
reperit, descripsit, et Iconibus illustravit Otho Fredericus Miiller. Lipsiie
et Havnia, 1785.

4 BRITISH ENTOMOSTKACA.

part ignorant of them, which they nevertheless produce
in the economy of nature ;* that these things are very
worthy of being known scarce any one will doubt. Not
to mention their external similitude to shells, and the
natural transition which takes place in them, from insects
to testaceous animals, who ever knew, before the Cypris
was detected, of an insect quadruped? Before the
Limulus and Caligus were properly observed, who ever
knew of an insect acephalous, or with a head at least
scarcely visible ? Who ever imagined of a copulation of
two males with one female at one time, such as takes
place in the famous Puleas aqiiftf/ctts ? or of an animal
whose head was all eye, as we see in the Polyphemus ?
These and more wonders are to be met with in the history
of the Entomostraca."

The greater number of these little creatures are
furnished with branchiae, either to their feet or maxillae,
and when noticed in their native habitats may be seen
to have them constantly in motion, their action being
seldom interrupted. One chief use, therefore, of them
in the economy of nature, may be, as Miillcr says, to
ventilate the water day and night ; and as they chiefly
reside in standing pools, they may thus be of great use
in preventing them from becoming soon putrid. As
this may be considered one of the benefits conferred
by these insects, it may be useful to know the evils
to man they may be likely to produce. Though they
are most abundant in stagnant water, they yet occur
in considerable numbers in the purer sorts of water that
serve as our common drink, and may frequently be seen
even in the drinking-water of London, Edinburgh, and
other large towns ; and Miiller asserts very gravely, that
as we thus drink them alive, and with their eggs, he
would not be surprised were we to discover them some
day in the human intestines. "The time," he says, "is
at hand, when the causes of disease shall not only be

* " It is (ho ronmiMii opinion Ilial il i> (lie C.iliu'i uliirli I'oivr tlir s
from (lie sea. \i|> river:- 1n\\;mU !!H' waterfalls."

INTRODUCTION.

sought after in the air, in our method of living, &c., but
in the incautious use of waters, often abounding in innu-
merable animalcules."*

According to Miiller and Straus, the greater number
of the Entoraostraca, not parasitical, live upon vegetable
matter, and not upon animals ; and the former, in an
experiment he instituted, says,f that in keeping a
number of species, such as the Daphnia pennata and
longispina, Cypris strigata and pilosa, Lynceus sphericus
and Cyclops quadricornis, in the same water from
the 24th of July to the 22d of January, during which
time the water had evaporated from a depth of five
inches to that of one, he frequently subjected small
quantities of this water to the microscope, and was never
able to discover any animalcules in it upon the most
attentive examination, though the intestines of the Ento-
mostraca themselves were seen to be full, sufficiently
proving that they had not fasted during that time. This
assertion, however, I am much inclined to call in ques-
tion. The Cyprides particularly seem to be most vora-
ciously carnivorous ; and I have invariably found it
exceedingly difficult to keep for a length of time any
other Entomostraca alive in the same vessel with the
larger species of Cypris. In a vessel, in which I have kept
full-grown Chirocephali, there were mixed with them
many specimens of the Cypris tristriata. In a few days
the Chirocephali might be seen to become languid in their
movements, and assume an unhealthy appearance. The
Cyprides had become their deadly enemy. They might
be seen ever and anon to fasten themselves to the delicate
feet of the poor Chirocephali, and wofully impede their
course through the water ; and when, either from these
annoyances, or from any other cause, they ceased to be
able to move with any degree of rapidity, hosts of these
little Carnivora might be observed to attack them before
life was extinct, anticipating as it were their victim's death.

* Entomost., p. 12. -j- Loc. cit., p. 7.

6 BRITISH ENTOMOSTRACA.

Then, when life had fairly ceased, they rioted upon their
flesh, and in a few hours little but the external covering
was left.

I have no doubt that most of the Entomostraca are
essentially carnivorous, and I have frequently seen speci-
mens of Cypris in their turn, as soon as dead, attacked
immediately by quantities of the Cyclops quadricornis,
who in a few minutes had fastened themselves upon the
dead animal, and were so intent upon their prey, that they
were scarcely frightened away from it by being touched
with the brush. In a short time the Cypris might be seen
lying at the bottom of the vessel, the valves of the shell
separated and emptied of their contents. Leeuwenhoek
and De Geer not only maintain that the Cyclops quadri-
cornis lives upon animalcules, but that it even preys upon
its own young, a fact which I have also noticed myself.
J urine asserts that the Cyclops quadricornis is carnivorous
from taste, and only herbivorous from necessity ; while
the DapUnia pidex, he distinctly affirms, lives upon ani-
malcules. Place a few Entomostraca, such, for example,
as the Daplmiae, Chirocephali, Lyncei, &c., in a vessel with
clear pure water, and only some vegetable matters in it,
and they gradually become languid, transparent, and finally
die ; but mix with this water some which contains nu-
merous Infusoria, and the Entomostraca will then be seen
speedily to assume another aspect. They become lively and
active, and the opacity of their alimentary canal testifies
sufficiently the cause of it. When, indeed, we consider the
amazing quantity of animals which swarm in our ponds
and ditches, and the deterioration of the surrounding
atmosphere which might ensue from the putrefaction of
iheir dead bodies, we sec a decided fitness in these Ento-
mostraca being carnivorous, thus helping to prevent the
noxious effects of putrid air which might otherwise ensue ;
whilst they in their turn become a prey to other animals,
\\liich no doubt serve their purposes also in the econoim
of nature. The fresh-water d'amman seem to prey upon
iliem, and tlie 1 1\ draehna1 are their decided enemies;

INTRODUCTION. /

" for," says Midler, " they seize hold of them while
swimming, by their feet, and daintily suck the life's blood
out of their captives with their sharp beaks."* " The
Hydrsef also, and not a few aquatic larvae, lay snares for
them, and many VorticeUse frequently grievously . infest
them, for they not only adhere, often in heaps, to the mem-
bers projecting beyond the shell, but also, nestling them-
selves within the shell, they overspread the whole body
with their own colonies, not a little retarding the motion
and agility of their host."! ^ne larva of the Corethra
jjhiHiiconiis, known to microscopical observers as the
skeleton larva, is exceedingly rapacious, more especially of
the Daplmise. They seize their prey with the rapacity of
a pike, grasping it with its two strong jaws, and gorging
them alive. § Pritchard says they are the choice food of a
species of Nais, which he calls the Lu-rco, and which de-
vours them in great numbers. || The CKydorus spliericus
is their especial favorite, and I have repeatedly verified
Pritchard' s observations, having counted at least ten in-
dividuals swallowed alive, and lodged in the different
stomachs of this eiutton. Those in the first and second

O

stomachs were still alive, while those contained in the iu-

* Eutomost. p. 8.

f "It would appear that there is something eminently poisonous to
animals in the fresh-water Hydrse. ' I have sometimes/ says Baker, ' forced
a worm from a polype the instant it has been bitten (at the expense of
breaking off the polype's arms), and have always observed it die very soon
afterwards, without one single instance of recovery.' To the Entomostraca,
however, its touch is not equally fatal , for I have repeatedly seen Cyprides
:u id Daphuise, entangled in the teutacula and arrested for some considerable
time, escape even from the very lips of the mouth and swim about after-
wards unharmed — their shell evidently protecting them from the poisonous
excretion." — Johnston, Brit. Zooph., 2d edit.,, p. 131.

J Loc. cit., p. 8. They are frequently covered completely with a small polype,
called by M. Reamur '" Polypes a bouquet ;" for an account of which see
Trembley's ' Memoire sur les Polypes a bouquet, a la suite des decouvertes
de Need'ham,' Leyde, 1747 ; also De Geer, ' Hist, des Ins.,' vii, 437, where
he informs us that in April 1742 he first observed this fact, and made a re-
port upon it to the Academy of Sweden, which that learned body inserted
in the Memoirs of the Academy in 1/47, previously to Mr. Trembley's work
being published.

§ Brightwell, Zool. .Tourn., v, 396 ; and t, xi.x, f. 1.

I) Microscop. Cabinet, p. 81.

b BRITISH ENTOMOSTRACA.

ferior ones were more or less partially decomposed. The
marine species are also preyed upon by their different
enemies ; amongst which are the Beroes. " The fact of
Beroes feeding upon small Crustacea," says Mr. Peterson,
" has Jbeen recorded by Eabricius, and at present appears
to rest upon his authority. It was interesting to observe
fl/e fact, which I did without knowing it was previously
known. The Crustacea were almost as visible in the trans-
parent body of the Beroe as they had previously been, and
very conspicuous by the bright green of their colouring."*
That the Entomostraca form a considerable portion of
the food of fishes has been long observed ; and it is very
probable that the quality of some of our fresh-water fishes
may in some degree depend upon the abundance of this
portion of their food. Dr. Parnell informs me that the
Lochlevin trout owes its superior sweetness and richness
of taste to its food, which consists of small shells and
Entomostraca. The colour of the Lochlevin trout, he
farther informs me, is redder than the common trout of
other localities. When specimens of this fish have been
removed from the loch, and conveyed to lakes in other
places, the colour remains ; but they very soon lose that
peculiar delicacy of flavour which distinguishes so remark-
ably the trout of Lochlevin. The experiment has been
repeatedly tried, and always with the same results. The
ban stickle devours them with great rapidity, and I have
seen two or three individuals clear in a single night a
large basin swarming with Daphniae and Cyclops, &c.

* Letter from Mr. Patcrson to Mr. Tcniplelon, in the Memoir oil AHO-
i/iiilocera, in Trans. Ent. Soc., ii, purl i, 39.

SYSTEMATIC ARRANGEMENT.

THE systematic arrangement of the Crustacea has been
a matter of considerable discussion amongst naturalists.

Desmarest, in his work,* has given a series of tabular
views of the various arrangements which different authors
have suggested, from Linnaeus to his own time. For a
complete view of these we refer the reader to him, and
shall only notice a few of the more prominent here, as far
as the Entomostraca are concerned.

Linnreus places the Crustacea in the class Insecta,
order Aptera, and refers all the species of Entomostraca
then known, with the exception of two, to one genus,
which he calls Monoculus. Eabricius also places the
Crustacea amongst the Insecta; the genus Monoculus,
embracing most of the Entomostraca, being placed in
his Class vin, Polygonata, and the genus Linmlus in the
ixth, Kleistognatha.f

Miiller, following his predecessors in arranging the
Crustacea amongst the Insecta, places of course the Ento-
mostraca in that class also.| He divides them into
two great sections, according to the number of eyes, viz.
Monoculi and Binoculi. These he subdivides again into
Univalves, Bivalves, and Crustacei, according to the form
of the shell or covering in which the animal is inclosed.

Latreille§ andCuvier, || in their first published Methods,
also placed the Crustacea amongst the Insecta, the former
adopting the arrangement of Miiller with regard to the
Entomostraca, and dividing them into two families, the

* Consid. geii. sur les Crustaces, 1S25.

f Systema Entomologiie, 1775 ; Eutomologia Systematic^, 1793.

£ Eutomostraca, 1785.

v; 1'recis des Caracteres gvn. dcs Inscctcs, 1796.

II Tableau clement, de 1'liist. Nat. dcs Animaux, 1798.

10 imi'lISH ENTOMOSTRACA.

Monoculi and Binoculi. Brisson, however, in his ' Regne
Animal/* as early as 175(1, had formed a distinct class
for the Crustacea, of which the Entomostraca formed a
part ; and Cuvier and Latreille, in their second Methods,
and in their subsequent publications, and all succeeding
authors, have adopted this arrangement, and have con-
tinued to place the Entomostraca with the great family
Crustacea, apart from the Insects.

Latreille, in his ' Hist. Nat. gen. et part, des Crust./
1802, divides the great class Crustacea into two sub -classes,
the Entomostraca and Malacostraca. The Entomostraca
he subdivides into two sections — Thecata, those inclosed,
1st, in a shield-shaped, or, 2d, in a bivalve-formed shell or
covering, and Gymnota, those in which the body is nearly
or entirely naked. The Thecata he divides into four orders,

«/

the Xiphosura and Pneumoneura, corresponding nearly to
the Binoculi of his first arrangement, and the Phyllopoda
and Ostracoda corresponding in part to his Monoculi.
The Gymnota he divides into two orders, the Pseudopoda
and the Cephalota, which include the remainder of his
Monoculi. In his ( Gen. Crust, et Insect./ 1806, and in
his ' Consid. generales/ 1810, he follows the same ar-
rangement ; and Leach, in the ' Edinburgh Encyclopaedia/
and again in the Supplement to the ' Encyclopaedia
Britannica/ adopts, in his articles on the Entomostraca,
one precisely similar, taking as the basis of his subdivisions
the covering or shell in which the animal is contained.
In the ' Diet, des Sc. Nat./ 1819, this naturalist adopts,
however, the structure of the feet as the basis of sub-
division, lie forms four orders: 1st, Psecilopoda, where
the feet in front are formed to walk and lay hold with,
and the others for swimming ; 2d, Phyllopoda, where the
front feet are formed like antenna', terminated by long
M-t;r, and the others formed for swimming; :Jd, Lophy-
ropoda ; and, 4th, I'ram-hiopoda, in which all the feet are
formed for swimming.

l.c KI^IIC Annual, divis. ni '.' Classes, •'••

SYSTEMATIC ARRANGEMENT. 11

Lamarck, in his 'Hist. Anim. sans Verteb.,' 1818,
divides the class Crustacea into two orders, the Hetero-
branches and Homobranches. The first of these is
divided into four sections, Branchiopodes, Isopodes,
Amphipodes, and Stomapodes. The second is divided
into two, the Macroures and Brachyures. The first
section of the first order, viz. the Branchiopoda, includes
all Midler's Entomostraca, and all the genera known up
to that time, except the genus Nebalia of Leach, which
is placed in the first section of the second order, the
Macroures.

Latreille, in his last Method, in the ' Regne Animal'
of Cuvier, vol. iv, adopts a new arrangement, using for
his principal subdivisions the organization of the mouth.
He divides the Entomostraca into two orders, the
Branchiopoda and Psecilopoda. The order Branchiopoda
contains those genera which have organs proper for mas-
tication, are possessed of branchiae attached to the feet
or jaws, and are for the most part inclosed within a
testaceous covering, either in the form of a buckler or
that of a bivalve shell. The second order, Precilopoda,
embraces those which are not provided with organs proper
for mastication, and are almost all parasitical, living upon
fishes and other aquatic animals. The first order, the
Branchiopoda, is divided into two principal sections, the
Lophyropa and Phyllopa. The first of these again is
subivided into three very natural groups or families, the
Carcinoida, Ostracoda, and Cladocera; while the second
is subdivided into two, the Ceratophthalma and the
Aspidiphora. The Psecilopoda, on the other hand, is
composed of rather heterogeneous materials, and is divided
into two families, the Xiphosura and Siphonostoma.*

• Latreiile appears to have been struck -with the resemblance which the
Lerneaj bear to some of the genera of the Siphonostoma ; but as he was then
not aware, of what has since been discovered, that the young of the Lerneae
undergo a metamorphosis like that of the Cyclopidse and Caligidie, and thai
the adults have the faculty of changing their skin or moulting, he considered
that the absence of these marks established a positive line of demarcation
lirt \\ceu them and the Entoinostraca.

\'2 IUUT1.S1I KXTOMOSTUAi A.

M. Milne Edwards, in his excellent work on the Crus-
tacea,' ;ulo])ts the organization of the month as the basis
of his arrangement also, lie divides the great class
Crustacea into three snb-cl asses. The first two of these
have an apparatus especially provided for laying hold of
the substances destined for their food ; while the third
has no such special organization, their masticatory organs
being the same as their organs of locomotion. The first
sub-class is that of the Maxilles, or those whose mouth
is furnished with organs for mastication. The second is
that of the Suceurs, or those whose mouth is furnished
with an apparatus for sucking; and the third is that of
the Xypliosuriens, or those whose organs of motion are
the same as the organs of mastication, and which differ
in many other points also from the first two. The
Maxilles he again divides into four legions: 1st, Podoph-
thalmiens, containing the orders Decapodes and Sto-
mapodcs ; 2d, Edriophthalmes, containing the orders
Amphipodcs, Isopodes, and Laemipodes ; 3d, Branchio-
podes, containing the orders Cladoceres and Phyllopodes;
and, 4th, Entomostraces, containing the orders Ostrapodes
and Copepodes. In this arrangement, the last two
legions of the Maxilles, the Branchiopodes and Entomos-
traces, correspond exactly with Latreille's first order, the
Branchiopoda, and form a very natural group. The sub-
class Suceurs, he divides into two legions, the Parasites
nageurs, containing the orders Siphonostomcs and Ler-
niVns ; and the Parasites mareheurs, containing the order
Araneiformes. The last sub-class, the Xyphosuriens, con-
tains the single order Xyphosures. In this method we
sec the Lerneac constitute a portion of Latreille's IVcilo-
poda, into which they were refused admittance by him.
They were placed by Cmicr, in his ' Regne Animal,'
amongst the /oophyta, and in general, till within a few
\ears, they were classed by naturalists amongst the
Venues. Dcsniaivst showed the relations the had \\illi

* Jlr-i. .\.-ii .n - i rustaci . suites a Huii'im. I M; I MI.

SYSTEMATIC ARRANGEMENT. 13

the Crustacea, and later observations still, especially those
of M. Nordmann, have proved them to belong decidedly
to this class. This latter naturalist has pointed out the
changes in form they undergo in their progress to matu-
rity, showing them when young to be very nearly of the
appearance of the young of the Cyclopidse, and under-
going like them a series of moultings before they reach
the mature state.

Another great addition has also of late years been
made to the class Crustacea. In consequence of the
increased attention that has been paid by naturalists to
the habits and formation of the molluscous animals,
the Cirripedes which formerly were generally considered
to be molluscous, from their being inclosed in a hard
shelly case, have now been proved to be crustaceous.
The observations of Thompson and Burmeister have de-
monstrated them to undergo a change of form in early
life, being, when first hatched, unattached and floating
freely about in the sea, and not attaining their perfect
shape till after several moultings have taken place.
Having, in addition to these relations, jointed, ciliated
limbs also, they approach very closely to the Entomos-
traca. Amongst them, indeed, they have been introduced
by Mr. J. E. Gray, in his arrangement of the Annnlosa,
in the Synopsis of the British Museum, 1 842.

The following table will give a connected view of the
arrangement of the British Entomostraca which I propose
to adopt.

14 BRITISH ENTOMOSTI!.\< \.

SUB-KINGDOM ANNULOSA.

CLASS CRUSTACEA—DIVISION ENTOMOSTHACA

LEGION FIRST— BRANCHIOPODA.
ORDER I.— PHYLLOPODA.

Family 1 — APODID^E, containing one Genus . . APUS.
Family 2 — NEBALIADJ^, containing one Genus . . NEBALIA.

Family 3— BRANCHIPODIDvE, containiugtwo Genera {

ORDER II— CLADOCERA.

!DAPHNIA.
MOINA.
^CROraBIS
SlDA.
DAPHNELLA.

Family 2— POLYPHEMID.E, containing two Genera . { .,"

fEuRYCERCUSc

I CHYDORUS.
I CAMPTOCEBC i s
Family 3 — LYNCEIDyE, containing seven Genera . .^ ACROPERUS.

ALONA.

PLEUROXUS.

JPERACANTHA.

LEGION SECOND— LOPHYIIOPODA.
ORDER I— OSTRACODA.

Family 1— CYPltlDIM, containing five Genera . .

"CYPRUS.
CANDONA.

CYTIIEKE.
CYTIIEKKIS.

ORDER II— COPEPODA.

("CYCLOPS.

Family 1 -CYCLOPID.E, containing four Genera . . ] J^JjjJJJJ1

C. ALT 1. 1 TII \.
("DlAPTOMUS.

Fniiiily 2— DIAPTOMID^E, containing three Genera . ] TEMORA.

F:imily 15— CETOCHILIDyE, fonlaiiiing one Genus . CETOMIII.I 8.

* *
Placed here provisionally, Genus . . NOT •i.rnvs.

SYSTEMATIC ARRANGEMENT. 15

LEGION THIRD— P^ECILOPODA.

ORDER I-SIPHONOSTOMA.

Tribe 1— PELTOCEPHALA.

Family 1 — ARGULID./E, containing one Genus . . ARGTJLUS.

/"CALIGUS.
Family 2— CALIGIM, containing four Genera . . 5

V^

Family 3— PANDARIM, containing two Genera . . {
Family 4— CECROPID.E, containing two Genera . •

Tribe 2— PACHYCEPHALA.

Family 1 — ANTHOSOMADJE, containing one Genus . ANTIIOSOMA.
Family 2 — ERGASILID^E, containing one Genus . NIOOTHOE.

ORDER H— LERNEAM.
Tribe 1— ANCIIORASTOMACEA.

Family 1— CHONDRACANTHIDJ5, containing two J

Genera t LERNENTOMA.

Tribe 2— ANCHORACAEPACEA.

Family 1 — LER.NEOPODADYE, containing one Genus... LEBNEOPODA.
Family 2 — ANCHORELLAD^E, containing one Genus... ANCHORELLA.

Tribe 3— ANCHORACERACEA.

Family 1 — PENELLADJ5, containing one Genus . . LERNEONEMA.
Family 2-LERNEOCERAD^ containing two Genera

ENTOMOSTRACA.*

Si/n. ENTOMOSTRACA, Miiller, Entomostraca, 1785.

Latreille, Precis des Caractcres geuer. ; Hist . "N a i .
gen. et part, des Crustac. ; Genera Crustac. c!
Insectorum ; Cuv. Regne Animal.
Leach, Edinburgh Encyclop. ; Encyelop. Britann. ;

Diet, des Sc. Nat., xiv.
Dumeril, Zoologie analytique.
Risso, Hist. Nat. des Crust, des Envir. de Nice. ;

Hist. Nat. de 1'Eur. merid.
Desmarest, Consid. gen. sur les Crust'
/. E. Gray, Syuops. of Cont. of Brit. Mus., 1842.
ASPIDOSTRACA or ENTOHOSTRACA, and SlPHONOSTOMA, Burmeister,

Organization of Trilobites (Ray Society's
edit.), p. 34.
MONOCULUS, Linnaeus, Syst. Nat., 1st edit., 1735 ; et edit, subseq. ;

Faun. Suec., 1st edit., 17 K>.

Fabricius, System. Entoniolog. ; Entomolog. Systemat.
Cucier, Tab. element.
Cuvier et Dumeril, Anatomic comparee.
Gcoffroy, Hist, abreg. des Ins. des Eiivir. dc Paris.
Manuel, Encyclop. method.
BRANcniOFTERES and ENTOMOSTRACES, Blaiimllc, Priuc. d'Auat.

comp.

LES MONOCLES, Jurine, Hist. Nat. desMonoc. des Envir. de (Jrui-u'.
CRUSTACES SESSILIOCLES, Lamarck, Syst. Anim. s. Vert., 1801.
BRANCUIOPODES, Lamarck, Hist. An. s. Vert., 1st edit., 1818.
Bosc, Man. de 1'Hist. Nat. des Crust.

Character.— -*$%& Entomostraca may be characterised
by their being all aquatic; by their being covered wit li
a shell or carapace, which is of a horny or coriaceous
texture, and formed of one or two pieces, in some ap-
proaching in appearance to a bivalve shell, in others being
in the form of a buckler, which completely or in great
part envelope's the body of the animal; by their haxinu;
branchia: attached either to the feet or organs of masti-
cation ; by their feet being jointed, and all more or less

* From H-rn/dir, an ii;srct : and >^rr,<i\<n\ a

PHl'LLOPODA. 17

ciliated ; and by their undergoing a regular moulting or
change of shell as they grow, in some amounting to a
species of transformation.

LEGION I— BRANCHIOPODA.*

BRANCHTOPODA (pars), Lamarck, Hist. An. s. Vert., 1818.

Latreille, Cuv. Regne Anim., 1829.
— M. Edwards, Hist. Nat. Crust., 1840.

MONOCULUS, Linnceus ; Fabricius ; Latreille (minus Lynceus), Prec. des
Car. gen.

Character. — Mouth furnished with organs fitted for
mastication ; branchia3 many, attached to the feet ; body
sometimes naked, but most frequently having an envelope
in form of a buckler, in some inclosing only the head
and thorax, in others the whole body ; feet vary in num-
ber, all branchiferous ; antennae two or four, jointed, and
generally ciliated ; eyes, sometimes two or even three,
but frequently only one, or so closely approximated as to
appear single. They are all free and unattached, swim-
ming at large in the water.

ORDER I— PHYLLOPODA-t

PHYLLOPODA, Latreille, Hist. Nat. Crust., iv, 130, 1802 ; Gener. Crust, et

Ins., i, 14.
Leach, Diet. Sc. Nat., xiv, art. Entomost.

— M. Edwards, Hist. Nat. Crust., iii, 351.
Desmarest, Consid. gen. Crust., 357.

— /. E. Gray, Synops. Brit. Mus., 1842.
Burmeister, Organiz. of Trilobites, 34.
Lucas, Explor. Sc. de 1'Algerie, Crust., 81."

PHYLLOPA, Latreille, Cuv. Regne Anim., iv, 171.

BRANCHIOPODES LAMELLIPEDES and BRANCPIIOPODES GEANS (in part),
Lamarck, Hist. An. s. Vert., v.

Character. — Body either naked or having only the
head and thorax covered by the carapace ; feet numerous,

* Bpayxia> branchise or gills ; and vovg, a foot.
f *v\Xoi', a leaf ; and TTOI/C, a foot.

2

18 BRITISH ENTOMOSTRACA.

varying from eleven pairs to sixty in number ; articula-
tions foliaceous and branchiform, being chiefly adapted
for respiration and not for locomotion ; eyes, generally
two, but sometimes three, in some situated at the extre-
mity of moveable pedicles ; antennae, sometimes only one
pair, but usually two, generally small, and not fitted for
assisting the animal in swimming ; mandibles for the
most part without palpi.

Family 1— APODHXE.

APUS, M. Edwards, Hist. Nat. Crust., iii, 356, et auctorum.
PHYLLOPODA, Leach, Eclin. Encyclop., vii, art. Crustaceology.
APODID.E, Bttrmeisler, Organization of Trilobites, 34. .

Character. — Antennas one pair, short and styliform ;
eyes three, sessile ; feet, sixty pairs, all branchial ; nearly
the whole body covered by a large shield-formed carapace ;
body composed of numerous rings or joints.

Bibliographical History. — The first notice we find taken
of any species of the genus Apus, is by Jacob Frisch, in
his ' Insecten in Deutschland,' torn, x, published at Berlin,
in 1732. He there gives a figure and description of nil
insect, which he calls " vom Floss-fussigen seewurm mit
dcm Schild." A specimen, he informs us, was sent to
him, well preserved in spirits, from Dantzic, by Klein,
who was then secretary of state. In this notice he indi-
cates, though rather vaguely, the use of the word Apus,
— a name which has since been given to the genus, and
by which it is now known. Soon after this, Klein sent a
short notice, with a tolerable figure of the same insect, in
a letter to Sir Hans Sloane, which was published in the
'Philosophical Transactions' for 1738. In this letter he
says that it was found at Uderwanga, in East Prussia,
amongst fresh-water crayfish, and that, from the great
number of its legs and their extreme mobility, he was
induced to call it the Scolopen$ra aquatica sciilaln. " As
long as the insect lives," he says, " so long does it continue

APODID.E.

19

to move its feet with constant and singular facility, with-
drawing the extreme part of the body, as it were into a
sheath, and again protruding it. I could find amongst
authors no trace of any insect of this sort." (p. 152.)

About the same time a number of specimens of the same
animal were found in Kent by the Rev. Mr. Littleton Brown,
F.R.S., who, in August 1736, sent a specimen, with a letter
to Dr. Mortimer, then secretary to the Royal Society, and
which is published, along with Klein's letter to Sir Hans
Sloane, in the 'Philosophical Transactions' for 1738,
No. 447. " I brought it," he says, " from a pond upon
Bexby (Bexley?) Common, where great numbers have
been observed for these five weeks past. The pond was
quite dry, the 24th of June, but upon its being filled with
the great thunder-shower, upon the 25th, within two days
the pond was observed to swarm with them, by a farmer
watering his cows there." (p. 153.)

Linnaeus, in his 'Fauna Suecica,' published in 1746,
mentions that he had seen a specimen dried of this animal,
in London, as early as the year 1728, at the house of a
naturalist, who told him that it had been taken in Prussia.

The chief early historiographer, however, of the genus
is Schceffer, who in his monograph ' Der Krebsartige
Kiefenfuss,' published at Ratisbon in 1756, gives a very
long and full account of almost all that was then known
concerning it, with well-executed figures of two species,
numerous anatomical details, and the progressive deve-
lopment of the animal, from the egg to maturity. His
description is very carefully drawn up, and Latreille, in
his ' History of the Phyllopoda,' has translated the greater
part of it into French, and thus rendered it more ac-
cessible to naturalists in this country.

Voschge, in a paper in the ' Naturforscher' for 1783, has
given a good many details, and a short but excellent de-
scription of the anatomy of the mouth is given by Savigny,
in his ' Memoires sur les Animaux sans Vertebres,' 1816.

Bosc, Latreille, Desmarest, and Milne Edwards have
repeated Schceffer's descriptions and observations in their

20 BRITISH ENTOMOSTRACA.

respective works ; and a good account of the circulation
of the blood has been given by Gaecle* and Berthold.t
For the fullest account, however, of the anatomy and
physiology of the Apus, since Schceffer's time, we are
indebted to Ernest G. Zaddach, who published a thesis
at Bonn in 1841, containing many most interesting par-
ticulars of the historv of this curious animal, j

j

Anatomy and Physiology, 8fc. — The body of the animal
is almost completely concealed by the carapace, which is
very large, oval -shaped, and covers the head and thorax
like a shield. It is rounded anteriorly, and deeply
notched at its hinder part. On the back of the cara-
pace, more especially towards the posterior extremity, we
see a slight keel, which, as it approaches towards the
anterior end, divides right and left, into a sort of fork,
indicating there the division into cephalic and thoracic
portions. The cephalic portion is the smaller of the two,
and it is to this portion alone that the body of the animal
is strongly connected ; a muscle attaching it just where
the first articulation of the thorax takes place, to one point
in the centre of its under surface. The thoracic portion
covers the thorax and abdomen, without adhering to them
at all, except by a fine membrane, which is continued
from the point of attachment, and spreads over the whole
internal surface of the carapace. The upper surface is
convex, while underneath it is concave ; its substance is
of a horny nature, and not calcareous, is tough and ex-
tremely flexible, and possesses considerable elasticity. On
the lateral part of each side, (t. I, f. //), we see a
number of well-nmrked lines running obliquely, in an
arched form, and being rcflexed. These, according to
Zaddach, are canals, and were pointed out by Gaede and

* Beitriigc zur Anatomic der Insecteii, Wiedcmann's Zoologisches Ma-
Kfi/.in, L817.

t Isis, L830.

J DC Apodi* fancriformis ; Schreff., Anatomc et ITistoria cvolutionis.
Bonnac, 1841.

APODID.^. 21

Berthold, to be blood-vessels. Zaddach describes them
very particularly, and reckons the number to be nine.
The internal plate or membrane which covers the inner
surface of the cephalothorax, according to the same author,
consists of a soft, spongy, cellular substance, and acts the
part of a branchial plate, or respiratory surface. The
whole carapace is called by him the " branchia maxima."

The eyes are two in number; large, compound, situated
on the upper part of the head, very close to each other,
of a reniform shape, projecting, and of a bluish-black
colour. They approach each other much nearer at the
upper part, leaving a considerable space between them
inferiorly. In this space we see a small elevation, smooth,
and whitish-coloured, which has been generally described
as a third eye. It is simple, however, in its structure,
not compound as the other two are, and thus presents a
great analogy to the black spot which accompanies the
eye in the LynceidaB, to be afterwards described.

When the Apus is laid on its back, and viewed from
underneath, we see at the upper part a small portion of
the carapace extending across, so as to form a plate, the
surface of which is on a level with the edges of the shell.
Inserted immediately under the edge of this plate, we see
the antennae (t. I, f. 6, <?). These are only one pair, are
very short, simple, and consist of two small cylindrical
articulations. Between these antennae is situated the
mouth (t. I, f. I), a}. This organ is composed, 1st, of a
superior lip, which is very large, firmly attached to the
centre of the plate described above, projecting downwards
so as partially to cover the mouth, and is of a quadri-
lateral shape (t. I, f. b, b 1) ; 2d, a pair of mandibles
(t. I, f. b, and f. a), each consisting of a thick, short,
curved body, terminated by a flat edge, which is furnished
with eight or nine strong teeth ; 3d, an inferior lip, con-
sisting of two lobes and a longitudinal gutter, and which
Savigny describes as a bifid tongue ; and, 4th, two pairs
of jaws (t. I, f. 0, a 1 , a 2) ; the first pair consisting of two
parts, the chief of which is a plate ciliated and toothed

22 BRITISH ENTOMOSTRACA.

at its extremity ; the second pair consisting of two portions
also, the internal of which is a short oval plate, ciliated
at its edges ; and the external longer, cylindrical, and
surmounted with a styliforin appendage.

The body of the animal, consisting of the thorax and
abdomen, is of a nearly cylindrical shape, and is composed
of thirty articulations, which are joined to each other by
means of a membrane that permits a considerable degree
of motion. They diminish gradually in size as they reach
the posterior extremity, which projects for some distance
beyond the carapace, and are studded all over with short,
stout, hooked spines.

The feet are very numerous, amounting to about sixty
pairs, and extend from the mouth downwards, lying
along the edge of the alimentary canal. The first pair
(t. I, f. d} are very long compared with the others,
are situated immediately behind the mouth, and are
ramiform. They are composed of a basilar portion, and
several appendages. The basilar part is divided into
three joints : the anterior joint gives off two very long,
cylindrical, moveable appendages, which consist of nu-
merous small articulations (the one having about sixty
and the other about fifty), and a short, flat body ciliated
on its edges, which Schoeffer describes as a claw-like pro-
duction. The middle joint gives off another numerously
articulated cylindrical appendage, formed exactly like the
other two, but shorter (having only about thirty articula-
tions), and, like them, possessing a great extent of motion ;
while the posterior joint gives off a fourth, somewhat simi-
lar, but much shorter (having only six articulations), and
apparently not possessed of any motion. At the extre-
mity of this joint are several ciliated bodies, which Schccffer
calls false teeth* (one being round and possessing very
short seta3, the other oval and having about thirty long-
ones); and underneath we see attached to the middle joint
a branchial plate, of a triangular form, with strongly

* The figure I have .i;ivcn of (his pair of feet, being taken from the. organ
in ait u, these parts arc not exhibited.

APODID^E. 23

ciliated edges, and another of an oval shape, which
Schoeffer says is of a red colour when the animal is alive,
and is swollen into the form of a small sac or vesicle.
This first pair of feet are the principal organs of motion
which the animal possesses, and have by many authors
been mistaken for and described as the antennae ; and cer-
tainly their length and the numerous small articulations
of which they consist cause them to resemble very closely
the antennae of the Decapods. They are more properly
called the rami. The other pairs of feet are branchial,
and do not serve the purpose of locomotion. They are
much broader, shorter, and of a lamellar structure, and
gradually become smaller and smaller as they descend in
the series, till at last they are merely rudimentary. As
they serve for respiration, and not for locomotion, their
structure is considerably different from that of the pair
above described ; but though altered to suit their change
of function, we may still trace the same structure per-
vading the whole of them. The chief portion, as seen in
the first pair of these branchial feet (t. I, f. e) is of
much the same form and structure as the basilar portion
of the preceding pair, and like it is divided into three
joints. The anterior joint gives off two large lanceolate-
shaped fingers or claws, strongly dentated on their edges
(corresponding with the two long many-articulated ap-
pendages of rami), and a small one of similar structure,
which Schceffer denominates & false clato (corresponding to
the flat daw-like production of first pair). The middle
joint gives off a similar body, also dentated on its edges ;
and the posterior joint gives off a short, erect body, of a
somewhat similar structure (corresponding to the two
shorter, many-jointed appendages), while it is terminated
by the same ciliated-edged bodies as Schceffer calls, in the
first pair, false teeth. The triangular branchial plate,
with its strongly-ciliated edges, and the vesicular plate or
little sac of Schoeffer, are also here attached to the first or
anterior joint of the basilar portion. The eight succeeding
pairs are very much the same as those described above,

24 BRITISH ENTOMOSTRACA.

except that the fingers or claws successively become shorter
and broader, while the branchial plates and oval sacs in-
crease in size in the same proportion. These nine pairs
of feet are described by Schceffer under the name of claw-
bearing branchial feet. The tenth pair of the branchial
feet differ materially from all the rest (t. I, f./), and as
no males have as yet been met with, we can only describe
them as they exist in the female. The basilar portion,
consisting of three joints, is not distinctly seen, being
merely a membranous expansion, although we trace the
same number of claws and other bodies described in the
preceding feet, but shorter and broader, whilst the tri-
angular branchial plate and oval sac have assumed the
appearance of two circular plates, one a little larger than
the other, and attached to its fellow by a kind of hinge-
joint, which allows them to be folded over upon each
other, thus forming a kind of capsule. In place of being
transparent and colourless, like the branchial plates in
the other feet, these are full of little round spots, like
grains, of a bright red colour, and which, when examined
by the lens, are seen to be eggs. This pair of feet may
therefore be considered as a sort of external ovary,-
SchoefFer calls them ovarian feet. In the centre of the
membranous basilar portion we observe a small, reddish
spot, surrounded by an elevation in which there is an
opening that will admit of a small bristle being intro-
duced. Schceffer considers this to be the situation of
the organs of generation. The eleventh (t. I, f. y) and
succeeding pairs of branchial feet, assume a different ap-
pearance from that of the ten preceding. The basilar
portion is much shorter, and apparently consists only of
one joint. The external finger, or claw, is much larger,
and semicircular, but of a membranous structure, and
the others, though of the same number, arc shorter and
broader than the corresponding appendages of the other
feet. The oval sac is rather narrower and more elongated,
and the branchial plate is more rounded and broader,
while on its external edge, instead of the numerous fine

APODIDyE. 25

setae which beset it in the preceding, there are only a few
(about twelve) longer tubular and plumose setae. They
differ, however, still further in this particular, that in this
pair we observe, between the hinder portion of the
branchial plate and the external claw, another plate make
its appearance, of an ovoid shape, and edged with short
setae. These feet are called by Schceffer the lamellar
branchial feet. As they succeed each other, we see the
external claw become gradually more round-shaped, and
the branchial plate lose, more and more, its triangular
form, till it becomes quite oblong, while the organs them-
selves become so small, that they are at last only rudi-
mentary.

The tail consists of one segment, larger and flatter
than any of the immediately preceding ones of the ab-
domen, which are nearly cylindrical. It is marked by
three short, blunt projections at its extremity, and gives
off two very long, round appendages, each consisting of
an immense number of small articulations ; Schceffer
counted them, and found each to consist of 480 joints.
As the animal can give a degree of motion to these ap-
pendages, they may be useful as a sort of rudder, to guide
its movements through the water. In the centre of this
caudal segment, between these two long appendages, is
situate the anus.

The number of articulations, or separate pieces, of
which the body of these animals is composed, is extraor-
dinary. Schceffer, with wonderful patience, undertook
the task of counting them, and in a table, in which he
enumerates them seriatim, reckons the number to be
1,802,604 ! and Latreille says that we may safely take
them to be not less than two millions ! !

The Apus inhabits stagnant waters, though they are by
no means so commonly to be met with as many of the
other kinds of Entomostraca. They appear to be more
local, and sometimes disappear from their usual haunts,
reappearing some years afterwards in the very same place.
" In warm, cairn weather," says Schceffer, " they assemble

26 BRITISH ENTOMOSTRACA.

upon the edges of the ponds, and nearly on the surface
of the water, but in stormy or cold weather they are no
longer to be seen." They can swim as freely upon their
back as on their inferior surface, and in both these posi-
tions we may see their feet continually in motion, alter-
nately from below upwards, and from right to left,
fatiguing the eye to follow them. Indeed their branchial
feet seem never at rest, for when the animal no longer
uses its rami, but floats idly on the water, these organs
are still in rapid motion, causing a sort of whirlpool in
the water, and attracting towards their mouth the objects
floating about them. Their chief food appears to be the
smaller species of Entomostraca, which generally are
found in great abundance in the same places, such as
Daphnise and Cyprides, the shells of which latter little
creatures they can easily break down by means of their
strong mandibles. Schceffer says they perish very quickly
after being taken out of the water, or when the ponds
dry up. It appears, notwithstanding, that after a pond
has been dried up for some time, and suddenly filled anew
by heavy rain, in two days these animals will be seen in
abundance. The eggs certainly retain their vitality long
after being dried, for these little creatures have been
known to appear in a ditch that was suddenly filled with
water after having been dried up for two or three years.
Frogs seem to be their chief enemy, and they are gene-
rally to be met with in a more or less mutilated state.

Professor Retzius, at the meeting of the German natu-
ralists at Breslau, in September, 1833, announced that
M. Kollar, of Vienna, had discovered the male of the
Apus cancriformis, but I have not been able to find any
detailed description of it.*

SchoofFer, Berthold, and Zaddach had considered them
to be hermaphrodites ; but in all probability the males
will be found, as in the case of the Daplnme, to exist at
some particular season of the year, and perhaps in small

*Isis, 1S31, p. 680; I'Wirp's Notizeu, 1833, pp. 38, 118; Durmcister,
Organ, of 'Mobiles, Kay Soc. rdit., p. 10, IS 10.

APODIDyE. 27

numbers only. Their method of copulation, therefore, is
as yet only conjectural. * That one copulation, however,
is sufficient for several generations, as in the case of the
Daphniae, &c., to be hereafter described, has been ascer-
tained.

SchoefTer tells us that he has carefully isolated the
young as soon as born, and found them to produce eggs,
from which a second generation was hatched. He also
found that the sun and open air were necessary for this
purpose, as he has kept them for a length of time in a
warm chamber during winter, without their ever hatching
their young ; but as soon as warm weather came on, and
the vessel which they were in was exposed to the sun and
open air, they hatched them in abundance. When taken
and placed in a vessel of clear water they may be seen
letting their eggs drop from the external ovary to the
bottom of the vessel, and in warm weather the young are
hatched from the egg in the space of about two or three
weeks, f At first they are very different from the parent,
undergoing a series of changes before they become fully
developed. The egg has two membranes ; one external,
coriaceous, the other internal, tender, and pellucid. When
it is ripe the external membrane opens at the upper part,
showing there a small red body, which may speedily be
observed to be in motion. This motion increases, at-
tempts seem to be made to burst the internal membrane ;
and then, after perhaps half a day, it suddenly leaps out
from its envelope, a living animal. The egg then falls to
the bottom, and loses its red colour, while the young
animal commences forthwith its motion to and fro through
the water. At first it is of a rosy colour, and an oblong

* Zaddach imagines that, he had discovered the male organ. " It consists,"
he says, " of a small round body near the mesial line on the dorsal part of
the last ring of the body, with a small portion on its apex surrounded by an
elevated margin." He had traced a nerve running to it. Should Kollar's
discovery be confirmed, this statement must "be attributed," to use Bur-
meister's words, " to a defective microscopic examination of the organs of
generation."

f Zaddach says twenty days.

28 BRITISH ENTOMOSTRACA.

figure (t. I, f. 2). On the upper part a small black
point represents the eyes ; and the first pair of feet, or
rami, are very large, nearly as long as the animal itself,
without articulations, and with only a few hairs at their

tt

extremity. The antenna? are large, and project beyond
the edge of the shell, having three rather long setae at
their extremity, but the tail is not yet apparent. In fact
at this period of their life, those portions of the body
which in the adult are the largest, are scarcely visible,
whilst those which are then small are now largely deve-
loped. The motion of the little creature in the water is
more that of leaping than swimming. At the end of
twenty-four hours they have become of a white colour,
and about this time they undergo the first change of skin.
The body then is sharper interiorly, and there is the
appearance of a tail terminating in two points. The rami
are divided into three parts, each furnished with several
hairs. The branchial feet are also more visible, though
still incomplete, and the antennas, with the three setae,
are even more largely developed still ; the eye, too, has
become larger. After one or two davs more the animal

O ^

assumes a yellowish colour, and the body is larger and more
pointed, while the rami and antennae have become smaller.
The eyes and the branchial feet, on the other hand, have
become more remarkable, and the tail begins to show
its terminating appendages (t. I, f. 3). They grow gra-
dually larger till about the fourth or fifth day, when they
have assumed their proper form, but not their full size.
The carapace has now its perfect shape, and upon its head
is seen a large green patch, in which maybe observed the
eyes, of a black colour. The antenna; are still large
enough to pass beyond the edge of the buckler, while the
rami, though not quite perfect, are now furnished with
their ordinary long appendages, but not articulated. The
mandibles arc visible, of a yellowish colour; the tail and
its long appendages are tolerably perfectly formed, and
the branchial feet nearly fully developed. At the end of
eight or ten davs thev have acquired considerable size,

APUS. 29

and go on gradually increasing, till, at the end of three
weeks, they have reached the size of one inch in length.
The process of moulting, or changing their skin, takes
place abont twenty times in the space of between two and
three months, at which time they seem to have attained
their full size. Schceffer says, he never witnessed the pro-
cess of moulting so as to be able to describe the mechanism,
but it no doubt is the same as will be more fully described
hereafter, when treating of the Daplmise.

Schceffer performed several experiments upon the Apus
to ascertain whether it possessed the faculty of repro-
ducing mutilated members. He found it had not, and
that after moulting, the truncated members remained
shorn of their fair proportions. It appeared, however,
that the excision of one or two of its feet, or part of its
rami, produced no bad consequences to the health of the
individual so treated.

This family contains only one British genus — Apus.

Genus APUS.*

C, Frisch, 1732.
APUS, Schceffer, Latreille, Bosc, &c.
MONOCULUS, Limueus, Fabridus.
BINOCULTJS, Geoffrey, LeacJi, Diet. Sc. Nat., xiv, 538.
LIMULUS, Miiller, Lamarck.
TRIOPES, Sclwank.

Character. — As this family at present contains only
one genus, the characters given to it will be sufficient for
the genus also.

* A, privitive ; and Trove, a foot.

30 BRITISH ENTOMOSTRACA.

1. APUS OANCRIFORMIS. Tab. I, figs. 1, 2, 3.

MONOCULUS CAUDA BISETA, Liiiitaiiis, Eaun. Succ., 314, No. 1181, 1 7 10.

APUS CANCRIFORMIS, Schcejfer, Mou. d. Krebsart, Kiefenf., t. 1-5, 1 756.

— Latreille, Hist, Nat. des Crust., iv, 193, 1. 19-27;

Geu. Crust, ct Ins., ii, 15.
Saugny, Mem. sur les Auim. s. Vcrteb., part i,

p. 63, t. 7, f. 1.

Base, Hist, des Crustac., ii, 243.
Leach, Ediub. Encyc., vii, 3S4, No. 4.
Desmarcst, Consid. gen. sur les Crust., 360,

t. 52, f. 1.

Giterin, Icouogr. Ilegn. Auim. Crust., t. 3 J-, f. 3.
H. Eiltcdi-fk, Hist. Nat. des Crust., iii, 3fiO ;
Icon. Regue Auim., edit. Crochart, Crustac.,
t, 75, f. 1.

Bertltohl, Isis, 1S30, t. 7, p. 685.
Zaddach, de Ap. Cane. Auat. et Hist. Evolul .
Koch, Dcutsch. Crustac. H. xxxv, t. 4.
APUS MONTAGUI, Lcftrli, Enc. Brit. Supp., i, 405, t. 20, f. 1-3.
MOXOCULUS APUS, Linnaeus, Syst. Nat., edit, 10th, 175S, i, 635,

No. 3 ; edit. 12th, 1058, No. 3.
Gmelin, Syst. Nat., edit. 13th, 3006, No. 3.
Scqpoli, Eutomol. Caruiol., 413, No. 113S.
Les/ce, Aufang. dcr Naturges., 493.
r«ln'ii'i/is, Spec. Insector., i. 372, No. 3; Eatoiiiol.

Systemat., ii, 488, Supp. 305.
Voscltye, Der Naturforscli., x, 60, t. 3, f. 1-1 0.
BINOCULUS CAUDA BISETA, Geoffroy, Hist, abreg. des Ins., ii, 660,

t. 21, f. 4.

BINOCULUS PALUSTRIS, Wilier, Zool. Dan. Prodrom., No. 2407, 1? 76.
BKANCHIPUS CAXCRIFORMIS, Schcrffer, Element . Eutomol., t. 29, f. 1-5.
LIMULUS PALUSTKIS, J//'/Av, Eutomostraca, p. 127.
IJMULUS CANCRIFORMIS, La in i in'/,-, Hist. An. s. Vert., v, 215.
TIUOPES PALUSTRIS, Schrciiik, Faun. Boic., p. 251.
TIUOPS CANCRIFORMIS, Olccii, Lclirbiu-h dcr Xaturg., iii, 398.
ELOSS-FUSSIGEN SEEWURM, Frisch, Insect, in Deutsch., x, t. 1, f. a-g

SCOLOPENDRA AQUATICA SCUTATA, Kl<-i,i, Phil. Trans, for 1737, P. 150,

t. 1, f. 2 a-d.

Brown, Phil. Trans., 1737, p. 153.
KIEFENFUSS, Suhfr, Die Kcnnzcicli. dcr Inject., 1 97, 1. 2 I-, f. 153.

Descrijrtion. — This sj)ccies is about two inches and ;i
lialf'loiip;, and one inch and a half diameter; of a brownish-

NEBALIAD^E. 31

yellow colour, clouded with marks of a deeper hue. The
edges of the notch in posterior part of carapace are finely
toothed, those in the middle and posterior extremity being
the strongest and largest. The appendages of the first
pair of feet, or rami, are very long; the inferior being
frequently two inches in length ; the superior, one inch,
and curved, and the middle is about one third longer.
The caudal segment of body is short, and its two appen-
dages very long, being sometimes more than two inches
in length. The segments of abdomen are each studded
over with numerous, short, stout, hooked spines, of a dark
brown colour, while the long caudal appendages are fur-
nished with numerous short hairs, or setae.

Hab. — Pond on Bexby (Bexley?) Common, Rev. L.
Brown, 1767. Devonshire, Dr. Leach. Bristol, W.
Clayfield, Esq. Brit. Mus.

Family 2— NEBALIAD Jl.
NEBALIA, Leach, Desmarest, Latreille, M. Edwards, fyc.

Character. — Antennae two pairs, large and ramiform ;
eyes, two, peduuculated ; feet, twelve pairs, 8 branchial
and 4 natatory ; carapace large, inclosing head, thorax,
and part of abdomen almost as in a bivalve shell.

Bibliographical History. — Otho Fabricius was the first
who described any species of this genus. In his c Fauna
Grcenlandica,' 1780, he mentions finding on the sandy
shores in Greenland, chiefly at the mouths of rivers, a
small Crustacean, occurring sparingly, which he describes
under the name of Cancer bipes.

In 1796, Herbst, in his ' Krabben,' vol. ii, p. Ill,
describes the same animal, placing it among the Gam-
mari, under the name of Cancer (Gammarellus) bipes.
Montagu is the next author who has personally noticed
the genus, and is the first observer who has described it

32 BRITISH ENTOMOSTRACA.

as British. He read a paper before the Linnean Society
in April 1807, which is printed in vol. xi of their
c Transactions ;' in which he describes and figures a spe-
cimen found by him in Devonshire. He refers it to the
Linnean genus Monoculus, under the name of Monoc.
rosfrafus, and says it is the largest species of that genus
he had ever found in England.

Dr. Leach, in his ' Naturalist's Miscellany,' vol. i,
p. 99, published in 1814, describes it more fully than
Montagu, and says the species he describes is not un-
common on the south-western and western coasts of
England. As he saw that it constituted a very distinct
genus from any previously given by modern writers,
he formed the genus Nebalia to receive it, and adds,
" in a systematic work this genus would hold a very
conspicuous and important place, as it is not refer-
able to any family hitherto established." In a paper
published soon afterwards by him, in vol. xi of the
' Linnean Transactions/ on the Arrangement of the
Crustacea, he assigns its place amongst the Malacostraca,
in the order Macroura ; in which he is followed by
Lamarck, Bosc, and Desmarest, Latreille, Olivier, and
Risso ; the three latter authors, however, referring the
species described to the genus Mysis.

We are indebted to M. Edwards for a more detailed
anatomical account of this interesting genus, and its true
place in the systematic arrangement. In a paper pub-
lished by him in the 'Ann. des Sc. Nat., t. xiii, 1828,
he shows from its structure, which we shall describe
shortly, that it does not belong to the Dccapoda Macroura,
but in reality must be placed amongst the Branchiopoda ;
an opinion which he confirms in the 'Ann. desSc. Nat.,'
2d series, t. iii, 1835, and in his work upon the Crustacea,
where he says it constitutes a passage between Mysis and
Apus. The details given in these papers with regard to
its anatomical structure, and the fact long ago mentioned
by the first observer of the genus, O. Fabricius, that it
carries its eggs under the body during the winter, and

NEBALIAD.E. 33

that the young are born in May, appear completely to
refute the opinion hazarded by Mr. Thompson, of Cork,
that they are most probably only the larvae of a Cirrhipede.

Anatomy, Physiology, 8fc. — In the Nebalia the cara-
pace is large, oval-shaped, and covers the whole of the
cephalo-thoracic portion of the body, and part also of the
abdomen. It is attached only to the head ; the thoracic
and abdominal segments being quite free and unattached.
It is not shield-shaped, as in the Apus, but descends upon
the sides, and incloses the portion of the body which it
covers, as in a bivalve shell ; the antennae, the natatory feet,
a portion of the abdomen, and the tail protruding beyond
it. In front, it terminates in a sharp-pointed rostrum or
beak, which is slightly curved downwards, and is move-
able.

The eyes are two in number, and may be seen pro-
jecting from under the anterior edge of the carapace,
on each side of the base of the rostrum. They are of
considerable size, and of a brown colour, " appearing,"
says Montagu, "in a strong light, crimson." They are
situate upon moveable peduncles, and are formed of a
transparent cornea, underneath which are a great number
of small crystalline bodies surrounded with a brownish
colouring matter.

The antennae are two pairs, both of them large and
ramiform, so that they are fitted to serve for swim-
ming. The first pair are situate immediately below
the eyes. They consist of a basilar portion, composed
of two strong joints, from the second of which spring
an oval ciliated plate, and a slender stalk divided
into nine or ten articulations, each articulation having
two or three hairs issuing from its base. The second
pair spring immediately behind the preceding, and are
bent so as to be directed at first obliquely forwards, then
downwards and backwards. The basilar portion consists
of three stout joints, the last of which sends off a long
stalk of about ten articulations, considerably longer than

3

34 BRITISH ENTOMOSTRACA.

those of the first pair, and having two or three short hairs
at the base of each joint.

The organs of the mouth consist of one pair of
mandibles and two pairs of jaws. The mandible is
composed of a basilar portion, which is short and pro-
vided with two large teeth curved inwards, and a long
palpiform branch, formed of three joints, of which the
last two are much the longest. Behind these mandibles
we see a small inferior lip, consisting of two slender
scales ciliated on the edges, and united by a peduncle.
The first pair of jaws (t. II, f. 1 a) are formed of a
stout basilar joint, which has on its internal edge a
ciliated plate, and gives origin at one extremity to a long
filiform stalk, which is directed first forwards, then is
curved upwards and backwards, and is prolonged to the
extremity of the thorax, between the internal surface of
the carapace and the flanks. This stalk is divided into
several articulations, each of which is furnished with long
hairs. The second pair of jaws have a very large basilar
joint, somewhat of a quadrilateral shape, the internal
edge of which is divided into several lobes, and strongly
ciliated, and the inferior edge gives attachment to two
branches, one of which is composed of two ciliated arti-
culations, and the other of only one. Succeeding these
organs of the mouth, we next find eight pairs of branchial
feet, inclosed entirely within the carapace (t. II, f. 1 b}.
They arc of a foliaceous structure, are very slender, placed
very close to each other, and are attached to the eight
thoracic segments of the body. Each of these branchial
feet consist of three portions : 1st, a lamellar piece,
forming the internal branch, and occupying the whole
length, and which, of considerable si/e at the base, becomes
much narrower at its inferior half; 2d, a large mem-
branous plate, nearly as long as the internal branch, to
^liieh it is attached at its upper external part; and,
lid, another membranous plate, placed between the two
.preceding, and attached also to the upper and external
edge of the internal branch.

NEBAL1AD.E. 35

The thorax is divided into eight slender segments,
completely concealed within the carapace ; and the abdo-
men consists also of eight rings, but which are consider-
ably longer and narrower than the preceding. The first
four of these are concealed by the carapace, and the other
four project beyond it. To the first four we find attached
the natatory feet (t. II, f. 1 c], consisting of four pairs.
These project from beyond the carapace at its interior
posterior portion, and are composed each of an elongated
basilar joint, which gives origin to two rather long, strongly-
ciliated branches and a very short, simple one. To the
fifth and sixth joints we see attached two pairs of what
have been described as rudimentary members, and which
resemble very much the fulcra or supporters of the ex-
ternal ovaries in the Cyclopidse. The penultimate joint
wants these organs, but the last gives off at its extremity
two rather long appendages, forming the tail. These
caudal laminae are smooth on their edges, and are fur-
nished with one long slender filament, and three or four
shorter ones, not plumose.

We know very little with regard to the habits of this
genus. Otho Fabricius tells us that it carries its eggs
under its thorax during the whole winter; that they
begin to hatch in the month of April, and that the young
are born in May ; they are very lively, he adds, and ad-
here to the mother, who appears then to be half dead. The
adult swims in a prone state, using its hinder feet to propel
it through the water. They are not very active. Montagu
informs us, that when moving in the water the superior
antennae are in constant motion as well as the abdominal
feet, but that the inferior antennas are usually motionless
and brought under the body. They are found, according
to Leach, on the south-western and western coasts of
England, under stones that lie in the mud, amongst the
hollows of the rocks ; and Mr. M' An drew dredged it
from a considerable depth amongst the Shetland Isles.

This family contains only one British genus.

30 BRITISH ENTO.MOSTRACA.

Genus — NEB ALIA.

NEBALIA, Leach, Zool. Miscell., i, 99, 1S14; Trans. Liun. Soc., xi, 351.

Thompson, Zool. Research., No. 3, 83.

Desmarest, Cons. gen. Crust., 24-3.

Latreille, Cuv. Regne Anim., iv, 153.

M. Edwards, Hist. Nat. Crust., iii, 353 ; Ann. Sc. Nat., xiii,
297 ; 2d series, iii, 309.

Risso, Hist. Nat. Eur. merid., v, 84.

Bosc, Man. Hist. Nat. Crust., ii.

Lamarck, An. s. Verteb., vi.
CANCER, 0. Fabricius, Faun. Greenland., 240, No. 223.

— Herbst, Krabbeu, ii, 111.
MONOCULTJS, Montagu, Trans. Linn. Soc., xi, 14.
MYSIS, Olivier.

As this is the only genus as yet belonging to the
family, the characters above given will suffice for both.

1. NEBALIA BIPES. Tab. II, f. 1.

CANCER BIPES, 0. Fabricius, Faun. Greenland., 246, No. 223, 1780.
CANCER (GAMMARELLUS) BIPES, Herbst, Krabben, ii, 111, No. 56,

t. 34, f. 7, 1796.
NEBALIA HERBSTII, Leach, Zool. Miscell., i, 100, t. 44, 1814; Trans.

Linn. Soc., xi, 351.
Desmarest, Cons. gen. Crust., 243.
Thompson, Zool. Research., iii, t. 11, f. 1.
NEBALIA GLABRA, Lamarck, An. s. Vert., v, 345.
Bosc, Man. Hist. Crust., ii, 83.
NEBALIA CILIATA, Lamarck, An. s. Vert., v. 3 15.

Bosc, Man. Hist. Nat. Crust., ii, 84, t. 13,

bis, f. 3.

NEBALIA MONTAGUI, Thompson, Zool. Research., iii, t. 11, f. 2.
MONOCULUS ROSTRATUS, Montar/H, Trans. Linn. Soc., xi, 14, t. 2,
f. 5, 1807.

Character. — Body ovate, of a pale yellow colour, with
a darker longitudinal line along each side ; antennae long,
the inferior pair as long as the body, and sctiferous ;
beak of carapace sharp-pointed and moveable ; natatorial
feet of moderate length, and sctiferous; caudal appendages

NEBALIA. 37

rather long, and furnished at extremity with one long
slender, and three or four short setae, not plumose.
Length, three eighths of an inch.

Montagu describes his species as possessing only three
pairs of natatorial feet, and in his figure represents them,
as well as the antennae and caudal appendages, as very
hairy.

Leach describes his as having five pairs of natatorial
feet ; and in his figure represents the antennas and caudal
appendages as without setae

The figures given by Fabricius and Herbst represent
their species also as possessed of five natatorial feet, and
the antennae and caudal appendages destitute of setae.

Lamarck, taking these as specific differences, makes
two species. The species of Fabricius and Herbst he
calls N. glabra, while that of Montagu and Leach he
calls N. ciliata. In this he is followed by Bosc ; but
Leach himself, Desmarest, and others, consider them as
identical.

It is evident that both Leach and Montagu have mistaken
the true number of natatorial feet, which have more recently
been shown by M. Edwards to be four pairs in all the known
species of this genus. Similar mistakes are frequently
made by the earlier observers of the minute Fntomostraca;
and when we consider the difference in the powers of the
microscopes made use of by different observers, we can
easily account for the discrepancies in the several figures
with regard to the amount of pilosity in the various parts
represented. The figures given by M. Edwards, for
instance, of the species which he describes under the
name of N. Geoffroyi,. do not show much pilosity, but
the enlarged figures of the details represent no small
array of setae in all the organs. I have no doubt, there-
fore, that the species described by Montagu and Leach,
as found in England, are identical ; and it is equally
clear that they are identical with that described and
figured by Fabricius, and reproduced by Herbst.

The specimens collected by Mr. Thompson, in Clifden

38 BRITISH ENTOMOSTRACA.

and Roundstone Bays, in the west of Ireland, in July
1840, and which were kindly lent me by that gentleman
for examination, agree remarkably well (with the excep-
tion of the number of feet, which were four pairs) with
the figure of Fabricius. As that naturalist was the first
observer of the species, it is but justice to restore to it
the specific name given by him, and call it Nelalia Mpcs.
As the name of Hcrbstii was given it by Leach, evidently
from a mistaken notion that Herbst was the first observer,
and as that author in reality only reproduces in his work
the figure previously given by Fabricius, it is still further
a matter of justice, and in accordance with the la\v of
priority, to restore its original designation.

Hal. — Coast of Devonshire, Montagu ; south-western
and western coasts of England, Leach (British Museum) ;
Clifden and Roundstone Bays, west coast of Ireland,
W. Thompson, Esq., 1840 ; Shetland Isles, R. M 'Andrew,
Esq., 1847.

Family 3— BBANCHIPODULK

BKANCHIPIENS, M. E<lt<-<n-ilx, Hist. Nat. des Crust., iii, 364.
BKANCHIOPODA, Leach, Diet, des Sc. Nat., xiv.
BRANCH i rt;siih£, Baird, Trans. Berw. Nat. Club, ISio.
BKANCniPiD.E, Burm-eister, Orgauiz. of Trilobites, BaySoc. edit., p. 34.

Character. — Body not inclosed within or covered by a
carapace of any kind. Two pairs of antennae, the inferior
being prehensile in male ; eyes two, pedunculated ; feet
11 pairs ; all branchial.

This family contains two British genera, Chirocephalus
and Artemia, closely allied to each other.

1. CIIIROCEPHALUS. — Tail formed of two well-developed
plates; inferior antennae or cephalic horns, in male,
cylindrical, and provided at their base with fan-shaped
and digitiform appendages.

2. ARTEMIA.— Caudal segment of body, simply bilobed,

CH1ROCEPHALUS. 39

and not divided into two plates. No appendages at the
base of cephalic horns.

1 — CHIROCEPHALUS.*

CHIROCEPHALUS, Prevost, 1803 ; Thompson.

BRANCHIPUS, M. Edwards, Fischer, Latreille, Desmarcst, Guerin, Lamarck.

INO, Schrank, 1803 ; Oken.

CANCER, Shaw.

Character. — Abdomen large, consisting of nine di-
visions, and terminated by two well-developed caudal
plates or lamellar appendages ; cephalic horns, of a cylin-
drical shape, and furnished with fan-shaped and digitiform
appendages in the male.

Bibliographical History. — A figure of the Chirocephalus
was given by Petiver, in his * Gazophylacion Naturae,' as
early as 1709. He mentions it as a native of England,
but merely describes it shortly, as " Squilla lacustris
minima, dorso natante." It was afterwards described at
greater length, as British, by Edward King, F.R.S., who
read, before the Royal Society, a short description of " a
very remarkable aquatic insect, found in a ditch of stand-
ing water, near Norwich, in the spring of the year 1762,"
and which is published in the ' Philos. Trans.' for 1767.
" They were discovered," he says, " by a poor man now
dead, whose genius was very extraordinary, and much
superior to what is usually found in his rank. He was
indefatigable in his searches after everything curious, and
without ever having had any advantages of education,
had acquired a degree of knowledge by no means con-
temptible. . . . In the ditch from which they were taken,"
he continues, " there were a vast multitude of the same
kind, though they have not been found in any other place
that I know of. From their being prolific in this state,

* I'roill Xal°; 'A llHllil : .'Hid vt^aXor head.

40 BRITISH ENTOMOST&ACA.

I suspect it to be their only one, and that they are merely
aquatic, and never turn to flies, as many insects found ill
water do." (p. 72.)

Linnaeus had, long previously to this, in his ' Fauna
Suecica,' 1746, noticed an animal which may, perhaps,
be the same as this. He inserts it at the end of the
volume, as if in doubt where to place it, and indeed de-
scribes it as a larva. He asks, "An larva Ephemerae?"
but at the same time particularly mentions the female as
possessing a small, yellow, shining globule, adhering to the
abdomen, and which, he says, is perhaps the ovary, ready,
as soon as the metamorphose is completed, to become
eggs.

A few years after this, Schceffer, while studying the En-
tomostraca, discovered, in a pool of water near Ratisbon,
a number of specimens of an " aquatic insect," very similar
to the species found in England. He published a long
description of it in 1752, under the name of Apus pisci-
formis, which he afterwards, in his ' Element. Entomol.,'
changed to JBrancMjsus pisciformis. Schceffer appears to
have dissected it very carefully, and gives figures of various
parts, as observed by the microscope ; but neither in his
description nor his figures does he take the slightest notice
of the peculiar complicated apparatus attached to the head,
which characterises so strongly the genus Chirocephalus,
and which, though roughly executed, is decidedly ex-
hibited in the figures given by King. Linnaeus, in the
meantime, having ascertained that his opinion, as to the
insect which lie mentioned in the ' Eauna Suecica' being
a larva, was erroneous, described it, in the tenth edition
of the ' Systems Naturae,' as a Crustacean, under the name
of Career stagnalis. His description is so short that it
is impossible now to ascertain whether the animal he men-
tions possessed this peculiar apparatus or not ; but Dr.
Shaw found it again in England, and published a length-
ened notice of it in the first volume of the 'Linnean
Transactions' for 1791. He does not state the locality
where it was found, but he describes and figures with

CHIROCEPHALUS. 41

considerable accuracy the peculiar apparatus attached to
the head, which he considered part of the mouth. He
carefully watched also the process of hatching the young
from the egg, and was the first to characterise and figure
some of the changes they undergo before reaching ma-
turity. He calls it by the Linnean name, Cancer staynalis,
and confounds it with the animal described by Schceffer.
This confusion is kept up byBosc and Latreille, who take
the details almost literally as given by Schceffer, but who
quote the descriptions of King and Shaw, as synonyms for
the same species as mentioned by him. Similar confusion
pervades the writings of all authors upon this subject till
the time when M. Benedict Prevost published an excel-
lent paper upon the genus, in the ' Journal cle Physique'
for 1803, giving a very minute anatomical description of
the animal, with a great many details concerning its habits
and development, from the egg to maturity. This paper
having attracted the attention of M. Jurine, of Geneva,
then busily engaged in studying the Entomostraca of that
neighbourhood, he wrote to M. Prevost, requesting him
to send some of the ova of the little creature he had de-
scribed so particularly. His request was immediately
complied with, and M. Prevost sent from Montauban to
Geneva a quantity of ova, wrapped up in moist paper.
These, though they were four days on the road, M. Jurine
with great care hatched, and succeeded in bringing them
to maturity. Having submitted the animals so reared to
frequent examinations and careful study, he was enabled
to verify all M. Prevost's facts and observations, while his
accomplished daughter, Mademoiselle Jurine, faithfully
portrayed them, as seen by the microscope. These
drawings having been placed at the disposal of Prevost,
and his original paper having received from his own hands
some emendations and corrections, were all published, in
1820, at the end of M. Jurine's work on the ' Monocles
qui se trouvent a Geneve ;' and the information given is so
full and precise, that little has been left to be added to the
history of this curious animal. He does not attempt,

42 BRITISH ENTOMOSTRACA.

however, to clear up the obscurity in which the species
described by Schceffer seems to rest. Fischer do Waldheim,
however, and Mr. J. V. Thompson seem to have published
in the same year (1834) a short attempt to do so; the
former making two distinct species, the first as described
by Schceffer, the other by Prevost ; while the latter makes
the species described by Schceffer as the type of the genus
Branchipus, and the one by Prevost as the type of the
Chirocephalus.

If Schceffer's details and figures are to be relied upon,
the species which he at such length describes does not
appear to have been ever seen, except by himself at
Ratisbon ; for all the continental writers who follow him
merely quote his description and figures. While the
species which have been noticed by observers in France
and Switzerland, such as Duchesne, in the ' Manuel du
Naturaliste,' Prevost, and Jurine, and by King, Shaw,
&c., in England, are all clearly referable to the genus
Chirocephalus.

Anatomy and Physiology, $'c. — The Chirocephalus is
of a slender, elongate form, the body being perfectly
naked and uncovered by shield or carapace of any descrip-
tion. We can readily distinguish a head, thorax, and
abdomen, all well developed.

The head consists of two segments, the inferior of
which is more slender than the superior, and is generally
described as the neck. Attached to this head we dis-
tinguish Ilir antenna?, eyes, and mouth.

The antenna1 we- shall find, in many of the Entomos-
traca, differ in the male and female.* In the Chirocephalus
I he difference is very striking. They are two pairs in
number. In the male, the superior (t. IV, f. A) are slender
and filiform, straight, extremely flexible, and composed of
a \cry great number of exceedingly minute articulations,
scarcely perceptible even with the aid of a microscope,

* Vide <lfMTipiii.il ,,(' ( '\i-|i.p-> ;,ml i.f |)ri|>liui:i.

CHIROCEPHALUS. 43

and terminated by several very fine short setae. They
are about the length of the head, take their origin from
its upper surface, a little above the root of the pedicle of
the eyes, and are directed upwards. They are jointed at
the lower third of their length, which adds to their
mobility, and are frequently put into motion by the
animal. The inferior pair (t. IV, f. B) are very remarkable,
and have been described by different authors as organs
totally different from antennae. Schceffer, who describes
them in the Branchipus, calls them tentacula, and
Latreille a sort of mandible ; while Prevost and J urine,
who describe them with their complicated attached
apparatus, call them hands. Their position, however,
upon the anterior segment of the head, seems, says M.
Edwards, to determine their true nature, though certainly
at first sight their conformation appears different from
what we usually see in these organs. They are essentially
prehensile organs, and consist chiefly of two large ap-
pendages which occupy the fore part of the head, and are
curved downwards towards the thorax. They are articu-
lated about the middle of their length, the first joint
being very large and fleshy, and having a short moveable
conical appendage on its external edge; the second being
curved, cylindrical, somewhat flattened at its extremity,
and having a strongly-toothed process at its base.

Arising from the base of the first joint of each of these
appendages, we see another organ of a singular conforma-
tion (t. IV, f. c and c*). It was first distinctly pointed out
by Shaw ,and has since that been also described by Prevost.
By the former it is called the trunk, and by the latter the
second finger. They each consist of a long, flat, curved,
very flexible body, composed of numerous short articula-
tions, strongly toothed at its edges, and evidently con-
sisting of numerous muscular fibres. On the outward
edge of each, near the base, there are given off four rather
long and very flexible appendages, strongly toothed on
their internal edge near the extremity, and a large mem-
branous triangular-shaped body which, when extended

44 BRITISH ENTOMOSTRACA.

(t. IV, f. D), can nearly cover the others, toothed, and, as it
were, vandyked round its external edge, and folding up
like a fan when the animal does not use it. These organs
are generally carried by the animal rolled round under
the head, and, as Shaw says, somewhat in the same
manner as a butterfly carries its proboscis, their situation
being externally visible only by a protuberance. During
copulation, however, they become extended in a, straight
line, and when so, they nearly equal in length the main
part of this curiously-formed organ.* These prehensile
inferior antennae are used by the animal to seize hold of
and retain the female in copulation, and seem exceedingly
well adapted for the purpose. In the female (t. IV, f. E)
they are differently and much more simply constructed,
being merely in the form of two short, stout, and some-
what sharp pointed and flexible horn -like bodies, pro-
jecting forwards when the animal is in the water, with
a slight curve downwards, and not provided with any of
the appendages described above as belonging to the male.
The superior antennae, however, are precisely similar to
those of the male.

The eyes (t. IV, f. F«) are very large, black, convex, oval-
shaped, and composed of an immense number of small
lenses, covered with a transparent cuticle. They are
situated at the sides of the head, and are fixed upon
considerable-sized peduncles, which take their origin
from nearly the same part of the head as the antennas,
and Avhich are conical-shaped and moveable, the ani-
mal having them almost always in quick motion in
all directions.! In the centre, between these organs

* Prevost finds much fault with Shaw's figure of this curious antenna,
especially with this proboscis-shaped portion of it. When fully extended,
however, as when compressed between two pieces of glass, the figure giveu
by Shaw, though ill proportioned and roughly executed, is a very fair rri>iv-
sentation of it. Jurinc's figures, though more elegantly executed, exhibit
it such as I have seen it in a very young male only partially extended.
Shaw, however, does not figure nor describe the membrane connected with
the four appendages, and erroneously represents only three of these in his
figure.

f Burmcistcr has described the structure of the eye of the Branchipus

CHIROCEPHALUS. 45

and on the front part of the head, we see a small, black,
smooth spot, of a somewhat triangular shape, and which
is generally described as a third sessile, simple eye. It
appears to be merely the mark remaining of what was
the eye in the young state, and will be more particularly
mentioned when describing the young animal and its
transformations.

The mouth is situated in the inferior surface of the
posterior cephalic segment, and consists of a lip, one pair
of mandibles, and two pairs of jaws.

The lip (t. IV, f. G) is large, projecting, curved back-
wards, and is prolonged below the other parts of the mouth.
It is articulated, and has considerable motion, enlarging
and contracting alternately. It is the " soupape" of
Prevost and Jurine.

The mandibles (t. IV, f. H) are also large, embracing
about four fifths of the circumference of the segment of
the head, to which they are attached, somewhat curved,
having the inner extremity large, obtuse, black, and
furnished at its edge with numerous very small teeth, so
fine as scarcely to be distinguished with the microscope,
while the other extremity is smaller, and terminates in a
sharp point.

at greater length. " It consists," he says, " of four successive layers of
different kinds. The external layer is a smooth, homogeneous, transparent
cornea. Beneath it lies a facetted membrane, which, seated in a clear sub-
stance, contains rather darker, firmer, circular apertures, of equal size, and
regularly distributed in such a manner that every ring is surrounded by six
others, at equal distances from each other. The third layer of the eye con-
sists of egg-shaped, transparent, very hard lenses, each of which is situated
behind one of the little window-like apertures described, resting upon the
surface of the latter with its flatter extremity, and raising this a little with
that convex surface. The fourth layer consists of an oblong, club-shaped,
crystalline body, which encircles with its upper thicker end the more pointed
end of the egg-shaped lens, and is surrounded by a delicate membrane. A
continuation of this membrane also overspreads the lens, and attaches itself
to the thickened margin of the little aperture before each lens. Behind the
crystalline body there then follows the dark pigment as the principal mass
of the whole eye, through which the fibres of the optic nerves extend them-
selves to the respective ocelli, resting on the basis of the crystalline body,
and the lenses, and through these sheaths likewise attach themselves to the
facetted second membrane." — Organization of Trilobites (Ray Soc. edit.),
p. 19.

46 BRITISH ENTOMOSTRACA.

The jaws (t. V, f. A) consist each of a small lamellar
somewhat triangular body, furnished at its edge with a
number of long bristles, about twenty-four in number.
They are the " barbilions" of the mandibles, of Prevost
and Jurine.

The thorax is cylindrical, and is composed of eleven
segments, each united to its fellow by a membrane, which
allows of a considerable degree of motion, permitting the
animal to curve its body in form of a circle, a position it
always seems to take when out of the water. The first
segment is the largest, the others gradually diminishing
in size as they descend.

To each of these segments is attached a pair of branchial
feet (t. V, f. B.) These are broad and foliaceous, and
consist of three articulations. The first is the largest;
and has on its lower edge a semicircular branchial plate,
giving off about thirty or forty beautifully plumose hairs;
the second gives off, on its inner edge, three square-shaped
projections, each of which sends off several long hairs ;
and the third is long and narrow, and gives off numerous
seta?, also plumose, and of considerable length. From
the first joint, near its juncture with the second, there
arises a vesicle or flat body, which is studded over with
minute points, but has no seta3 attached to it. It is of a
denser structure than the other portions. The first pair
of feet are the smallest, the others gradually increasing
in size till they reach the tenth pair, the eleventh being
considerably smaller than those preceding, though still
larger than the first.

The abdomen is composed of nine segments, the two
first of which are the largest, the rest gradually diminish-
ing in size as they descend to the tail. This consists of
two lamellar appendages of considerable size, and beset
round the edges with numerous beautifully plumose
set<e.

1 5el \veen the lir>t and second segment of the abdomen
we see iu the male the organs of generation, and in the
female the external ovary or ovit'erous pouch. The male

CHIROCEPHALUS. 47

organ appears to be double or bifid, cylindrical, transparent,
and, according to Schceffer, composed of two joints. The
oviferous sac, or external ovary of the female, is very large,
and distinctly visible. It is conical, and the point opens
like the beak of a bird, to allow the eggs to escape.
Prevost, however, informs us that the vulva is not situated
here, but what appears singular, is placed at the extremity
of the tail on each side of the anus, being double or bifid,
to correspond with the double penis of the male.

The heart or dorsal vessel commences near the head,
and terminates at the end of the penultimate ring of the
body. It is brilliant, quite diaphanous, and consists of a
series of small hearts, as Prevost calls them, to the
number of about eighteen or nineteen, all placed end to
end, and all moving together. It was pointed out by
Schoefter in the Branchipus.

The digestive canal, commencing at the mouth, at first
mounts up a little, then curves downwards, and runs
along the body, terminating in the anus, between the
caudal segments.

The Chirocephalus is found in stagnant water : very
often in the ditches and deep cart-ruts on the edges of
woods and plantations.

It is rarely to be met with in this country, compared
with the Daphnise, and many other Entomostraca : the
only place near London where I have met with it being
on Blackheath. They swim upon their back, and in fine
warm weather, when the sun is not too strong, they may
be seen balancing themselves, as it were, near the surface
by means of their branchial feet, which are in constant
motion. On the least disturbance, however, they strike
the water rapidly with their tail from right to left, and
dart away like a fish, and hasten to conceal themselves
by diving into the soft mud, or amongst the weeds at the
bottom of the pool. They are nearly transparent, and
are of a very light reddish colour, with a slight tinge of
blue on some parts. " When placed in a glass of clear
water," says Prevost, " the elegance of its form, the ease

48 BRITISH ENTOMOSTRACA.

and softness of its movements, its silvery transparency,
or its brilliant colours, its large black eyes, the small
spot which it carries on its head, the crown of the male,
are a beautiful sight, which the most indifferent observer
cannot see without pleasure." It is certainly the most
beautiful and elegant of all the Entomostraca. The male
is especially beautiful. The uninterrupted undulatory,
wavy motion of its graceful branchial feet, slightly tinged
as they are with a light reddish hue, the brilliant mixture
of transparent bluish green and bright red of its pre-
hensile antennae, and its bright red tail, with the beautifully
plumose setae springing from it, render it really ex-
ceedingly attractive to the view.

The undulatory motion of its branchial feet serves another
purpose in addition to that of keeping the animal suspended
in the water. The thorax or body of the animal has been
described, when floating on its back, as like the cavity of
a little boat, the feet representing the oars. When these
are in motion, they cause the water contained in this boat-
like cavity to be compressed, and to mount up as along a
canal, carrying in the current the particles destined for its
food towards the mouth. It seems to be constantly, when
in this position, employed in swallowing and digesting its
food, its masticatory organs being in perpetual motion.

Shaw imagined this little creature to be a fierce and
voracious beast of prey, but it is not so ; he was misled
in so thinking, by not understanding the true use of
its prehensile antennae. These he imagined were organs
for seizing its victims and crushing them to death ;
though he candidly admits that he never saw them attack
other animals, and even says that he has seen then)
succumb to the assaults of the Cypris. According to
Prevost, they live upon dead animal or vegetable matter;
but they have apparently little taste, for they swallow
every sort of thing that comes in their way, however
hurtful it may be. SchcefFer says that he found great
difficulty in keeping the Branchipus alive after having
been taken out of the water in which tliev were found, and

CHIROCEPHALUS. 49

also says that they are incapable of bearing any degree of
cold. Jurine, however, found no difficulty in hatching
the ova of the Chiroeephalus sent to him by Prevost, and
keeping the animals so hatched till they reached maturity ;
and Shaw distinctly asserts that he has found them in
this country in shallow pools, in the months of December
and January, even after pretty sharp frosts, as lively
almost as in spring or summer. I have always found
them in the months of October, November, and December,
and even after frosts of short continuance, though of con-
siderable severity. In general they have been very short-
lived after being removed from their native habitat, but I
have been able to hatch the young and watch their
progress to maturity. Though they do not appear de-
structive to other animals, they fall an easy prey them-
selves to various enemies. Frogs, salamanders, the larvae
of the Dytisci, the Cyprides, and other such inhabitants
of the water, kill them in vast numbers, and they seem,
besides, according to Prevost, to be specially infested by
a species of Vorticella, or wheel animalcule, which attaches
itself to the body of the animal in great numbers, and
would very soon, were it not for their moulting frequently,
completely destroy it. I have found them very liable to a
peculiar disease, which seems very frequently to terminate
fatally. It attacks their body near the external ovary, the
lower part of the abdomen, &c., and the branchial feet
are not exempt from it. It consists of a white growth,
composed of a fatty sort of substance, and when once
this appears, the poor animal almost always soon after dies.
When copulation takes place, the male glides under-
neath the female, and seizing her firmly with his
powerful prehensile antennae, forces her to bend her
tail towards his abdomen, where the male organs lie.
The ova appear at first as small, white, spherical bodies
lying in the internal ovary, which stretches along the
abdomen, and then passing from it into the external
ovary already described. When the proper time arrives,
the mother deposits these ova loose in the water, the

4

50 BRITISH ENTOMOSTRACA.

ovary opening at the point, and the eggs being thrown
out by a sudden jerk, to the number of ten or twelve, very
rapidly. The whole process of laying lasts several hours,
sometimes, accord wig to Prevost, for a whole day, and
the number of ova excluded vary from 1 to 400. At
first the egg is yellowish, spherical (t. V, f. 1), and in-
closed in a thick, hard envelope, beset all round with short
setae, but when it has been for a short time exposed to the
action of the air and water, it assumes an irregular
hexagonal figure, and a greenish hue. In about a fortnight
or so, the egg is hatched, and the young one issues forth,
but very unlike its parent. It consists of two nearly equal
oval portions, head and body.

The cephalic division possesses two very large antennae,
and two pairs of largely-developed natatory feet, the an-
terior much larger than the others, and both furnished
with a considerable number of stiff setae springing from
their under edge.

The eye is sessile, not compound, a single black spot,
situate in the middle of the fore part of the head, between
the antennae. There is at this time no appearance of the
pedunculated eyes, and it would seem that these require
considerable elaboration to come to perfection. In the
adult state, upon dissection we see these eyes furnished
with well- developed muscles and nerves, while there is
no trace remaining of any muscles, or vessels of any kind,
going to the black spot, the mark of which then still
remains.

In a short time after birth (longer or shorter accord-
ing to the temperature), the young creature throws off
its skin, or moults, and we then see a distinct appear-
ance of the two lateral eyes ; the body becomes much
increased in size, is divided into segments, and a series
of knobs or projections may be observed along its edges,
destined to become the feet, while at its extremity we see
a notch, with a filament from either side, being an ap-
proach to the formation of the tail. It soon moults a
second time, and we then see the buds, as it were, of the

CHIROCEPHALUS. 51

first three pairs of feet, which are not yet moveable, and
four pairs of small knobs or projections, the rudiments of
as many other feet. After moulting for the third time,
the first two pairs of feet have become moveable and
foliaceous, and we can distinguish seven pairs of rudi-
mentary feet. The eyes have become somewhat pedun-
culated, and the body more elongated. It continues to
moult frequently, and at short intervals, and we can trace
the conformation gradually approaching more and more
to that of the adult. The branchial feet become, after
each time, more developed, the eyes more perfect, while
the large natatory feet, which are so large and conspicuous
when first born, are gradually converted into the pre-
hensile antennae in the male, and the cephalic horns of
the female.

In January 1849, I had several specimens of female
Chirocephalus, which had been taken at Blackheath on
the 25th of December previous. These deposited their
eggs in the vessel in which they were kept, and though
the mothers died in about a fortnight after they were
taken, the ova were matured in the vessel, and the young
hatched. Upon submitting a mature ovum to inspection
under the microscope, 1 found the young animal inclosed
within a pure, transparent envelope, which again had evi-
dently had an external thicker and opaque coat over it.
This was more than half detached (t. V, f. 2). A few
hours afterwards, I found that this thick external covering-
was completely separated, and the young was then merely
inclosed in the transparent case. Twelve hours afterwards
it was still within its envelope, but it completely filled
it lengthwise. It was balloon-shaped (t. V, f. 3), per-
fectly transparent, and colourless, and the young animal
pushed frequently its head against the top of its case, as
if trying to burst it open. It could turn itself round,
however, from one side to another. In twenty -four hours
more I found the young animal just launched from its
prison into the world. Two or three hours after its birth
I submitted it to inspection through the microscope. At

. .

';

52 BRITISH ENTOMOSTRACA.

that time, 6th February, five p. m., it resembled t. V, f. 4.
The body was composed of two oval portions, of nearly
equal size ; the upper having attached to it a pair of long
antennae, and two large natatory feet ; the inferior having
no appearance of legs or tail, but being merely notched
at the extremity.

On the 7th of February, at six p. m., or about twenty-
four hours after birth, I found the abdomen had become
more elongated, being then longer than the thorax, and
had four slight protuberances, or knobs, on each side, at
its upper part, the uppermost being the largest. The
notched extremity had two short, sharp setse. The na-
tatory feet were the same, but the whole animal had
grown, and the eyes were visible, in shape of a black spot
on each side of the head.

On the 8th, at six p. in., or forty-eight hours after
birth, the thorax had become more square-shaped, and
elongated, and the lateral eyes were larger. The knobs
on each side of abdomen were six in number, the upper
being the largest, and having a short seta making its ap-
pearance at its extremity. The upper part of the abdomen
was more bulging out at the sides, where the knobs ap-
pear, and the whole animal was considerably elongated.

On the 9th, at six p. m., or seventy-two hours after
birth, I found the animal had grown in length. The
knobs were increased to eight, the three uppermost with
a seta each at its extremity. The alimentary canal was
very large, extending from a short distance from under
the central eye to the tail, taking up nearly half the
breadth of the whole body as it passes down. At the
upper part it forms a fork, with two short and blunt
divisions. The antennae, and upper pair of natatory feet,
continued much the same, but the lower pair had become
smaller in proportion to the size of the animal, and dis-
tinctly articulated ; the basal joint being large and fleshy.
The caudal setse were considerably longer. The central
eye was rather smaller, and the lateral eyes had become
areolar.

CHIROCEPHALUS. 53

On the 10th, at six p. m., ninety-six hours after birth,
it had become somewhat increased in length. The knobs
were nine in number, the four uppermost being free from
the body, and setiferous at the extremity, and much in-
creased in length. The antennse had diminished in length
in proportion to the body.

On the llth, seven p. m., about 120 hours afterbirth,
I found it had undergone scarcely any change in ap-
pearance.

On the 12th, 144 hours after birth, I found it en-
veloped in a covering of filmy, slimy stuff, which had
been floating about in the water. It had, notwithstand-
ing, gone on increasing in development. The knobs were
eleven in number ; the first six pairs free, and the three
or four superior pairs distinctly lamellar. The lateral
eyes had become distinctly pedicled, and on each side of
the median eye there was a slight projection or knob.
I was unfortunately prevented carrying my observations
farther.

The female begins to lay before she has attained her
full size, and lays several times during the season. Each
time the ova are transmitted from the internal to the ex-
ternal ovary, the animal throws off its skin.

1. CHIROCEPHALUS DIAPHANUS. Tab. Ill, figs. 1, 2.

CHIUOCEPHALUS DIAPHANUS, Prevost, Journ. de Phys., 1803, Ivii, 37,

1. 1, f. 1-3.

Jurine, Hist. Monoc., 201, t. 20-22.
BRANCHIPUS PKEVOSTII, Fischer, Bull. Soc. Imp. Nat. Moscou,

vii, 1831.
CHIKOCEPHAIAJS PREVOSTII, Thompson, Zool. Research., fasc. vii, t. 3,

f. 4, 5 ; t. 4, f. 1, 1831.

BRANCHIPUS CHIROCEPHAIAJS, Guerin, Icon. Reg. An. Crust., t. 33, f. 3.
BRANCHIPUS DIAPHANUS, M. Edwards, Hist. Crust., iii, 368.
BRANCHIPUS PALUDOSUS, Desmarest, Cousid. gen. Crust., 389, t. 56, f. 2.

Lamarck, Hist. An. s. Vert., 2d. edit.,
v, 198.

54 BRITISH ENTOMOSTRACA.

CANCER STAGNALIS (Linn. f), Shaw, Linn. Trans., i, 103, t. 9, f. 4, 5.
CANCEK PALUDOSUS (?), Midler, Zool. Daii., t. 48, f. 1-S.

Herbst, Krabben, ii, 118, t. 35, f. 3-5.
BRANCHIPUS STAGNALIS, M. Edwards, Cuv. Regiie Anini., edit.

Crochart, Crust., t. 74, f. 2.
INO PISCINA, Schrank, Faun. Boic., iii, 249, 1803.
MARTEAU D'EAU BOTJCE, Duchesne, Manuel du Naturaliste.
REMARKABLE AQUATIC INSECT, King, Phil. Trans., Ivii, 72, t. 4, 1762.
SQUILLA LACUSTRIS MINIMA, Petiver, Gazoph. Nat., i, t. 21, f. 7, 1709.

Description. — When full grown it is upwards of an
inch in length, slender, of a cylindrical form, and nearly
perfectly transparent. The male is more so than the
female, but with a slight reddish tinge throughout. The
tail is of a bright red ; the large basal joint of the
prehensile antennae of a beautiful transparent bluish-
green colour, tipped at the extremity, where the second
joint arises with a fine red hue. The back of the female
is of a blue colour, and the ovary, when full of ova, of a
reddish-brown.

Hob. — Pools on Blackheath, W. B. ; near Epping,
E. Doubleday, Esq. ; near Brighton, C. Ager ; near Bristol
and in Devonshire, Dr. Leach, Brit. Mus.; near Hammer-
smith, J. O. Westwood, Esq.

2 — ARTEMIA.

CANCER, Linnteus, Rackett.
GAMMARUS, Fabricius, Pennant, Herbst.
ARTEMIA, Leach, Desmarest, M. Edwards, Joly.
I '> K ANCHIPUS, Latrcille.
AKTEMISUS, Lamarck.
ARTEMIS, Thompson.

Character. — Abdomen long, consisting of six divisions,
shortly bilobed, and not divided into two caudal plates ;
cephalic horns of male flat, broad, and not furnished with
any appendages.

ARTEMIA. 55

Bibliographical History. — We are indebted to Dr.
Schlosser for the first extended notice of this little animal,
though he mentions it as having been indicated a short
time previously in the ' Journal Britannique.' In October

1755, having visited the saltworks at Lymington, in
Hampshire, he went to examine the salterns, or reservoirs
where the brine is deposited previous to its being boiled.
In this strong liquor he discovered a vast number of small
insects, of a red colour, which tinged the whole cistern.
These he examined with care, watched all their motions
as they gambolled in their native element, and noticed the
great difference which distinguishes the male from the
female. Having made a tolerably accurate drawing, he
wrote a description of them, and sent it in a letter to M.
Gautier, in Paris, who had just at that time discovered a
method of engraving in colours, and was engaged in pub-
lishing his work called ' Observations periodiques sur la
Physique.' This letter appeared in the year following,

1756, with figures of the animal, male and female.
Schlosser tells us that they were called by the workmen
brine-worms, and are chiefly to be found when the liquor
is very strong. Linnaeus, in his tenth edition of the
' Systema Naturae,' 1758, shortly describes it under the
name of Cancer salinus, and Fabricius, in his ' Entomolog.
Systemat.,' 1775, places it in the genus Gammarus, under
the name of G. salinus. No particular description of the
little creature, however, appears to be given by any per-
sonal observer after Schlosser's time, till the Rev. Mr.
Rackett called the attention of the members of the Linnean
Society to it, by reading a paper at their meeting, on the
16th of June, 1812, which was published in the eleventh
volume of their 'Transactions,' in the year 1815. Mr.
Rackett informs us, it is called the Lymington shrimp, or
brine-worm, and that it occurs in greatest number in the
salt-pits or reservoirs, where the liquor obtains the strength
of a quarter of a pound of salt to the pint of water.
When this liquor, he says, becomes much diluted with
rain-water, a few only are visible in it.

50 BRITISH ENTOMOSTRACA.

Hitherto it had been described either as the Cancer
salinus or the Gainmarus salinus, according as authors
chose to adopt the name given to it by Linnaeus or
Fabricms. Latreille, however, in the first edition of
' Cuv. Regne Anim.,' 1817, describes it as a species of
Branchipus, referring it correctly to the Phyllopoda ; and
Leach, in the 'Diet. Sc. Nat./ 1819, following up the
arrangement, founded the genus Artemia to receive it,
in which it has remained ever since.

More recently the Artemia salina has been studied with
care by Mr. Thompson, who, in the fifth number of his
'Zoological Researches,' 1834, informs us he received
some specimens of it from Lymington, and though the
adults all died, he succeeded in hatching the ova con-
tained in the brine, and bringing the young to maturity.
He readily distinguished the male from the female, and
has given a number of figures, illustrating the anatomy of
the adult animal, and the various changes which the young
undergo in their progress to maturity.

More lately still, M. Joly, of Montpellier, having found
the species abundant in the salt-marshes in that neigh-
bourhood, and more especially in the salt-pits or reservoirs,
has devoted much attention to its study, and published a
lengthened description of its anatomy and habits in the
' Ann. Sc. Nat./ 1840. It seems curious, however, that
he does not appear ever to have seen the males, and even
asserts that Schlosser must have mistaken the young in-
sect for the male, and that the horn-like antennae, which
he describes, must have been the provisional feet of the
young before they had assumed the adult form. Appa-
rently he had not seen the memoir of Thompson. In other
respects his paper contains the fullest description, with the
most copious and most accurate account of the manners
and habits of this little creature, that has been published,
and is concluded by a lengthened disquisition as to the
cause of the red colour which frequently distinguishes
them, and which tinges the whole water in which they
occur with the same hue

ARTEMIA. 57

Anatomy and Physiology, 8fc. — The Artemia resembles
the preceding genus so much in anatomical structure, that
it is unnecessary to enter fully into details. The superior
antennae in both sexes, and the inferior in the female, are
exactly similar to those of the Chirocephalus (t. II, f. 2 b}.
The prehensile antennae of the male (t. II, f. 2 a) differ,
however, in two or three respects. They are large, flat, and
curved downwards towards the thorax, as in the Chiroce-
phalus, and are also divided into two articulations. The first
articulation is much more simple than that of the Chiro-
cephalus, and has none of the complicated apparatus
attached to it which is so remarkable in that genus ; while
the conical, antenna-like appendage is firmly attached to
its inner edge, and is not moveable. The second joint is
flat, broad, bent nearly at a right angle about the middle
of its length, and sharp-pointed.

The two lateral pedunculated eyes and the median
sessile, black spot are precisely similar to those of the
Chirocephalus, and the organs of the mouth do not differ
in any circumstance but in the lip being rather more
developed.

The divisions of the thorax are not quite so distinct as
in the Chirocephalus, but they are of the same number,
and as each division has attached to it a pair of branchial
feet, these organs consist also of eleven pairs, notwith-
standing that Latreille, followed by Desmarest, asserts
they have only ten. In structure they resemble almost
exactly those already described in the preceding genus
(t. II, f. 2 c). They gradually increase in length from the
first to the sixth, and decrease again from that to the
eleventh.

According to Joly, the abdomen is only composed of
six instead of nine articulations. The first has the ex-
ternal ovary attached to it in the female and the organs of
generation in the male, while the last is by much the
longest, and terminates in two short, conical prolongations,
furnished at their extremities with a few short hairs.
The external ovary is of a somewhat quadrilateral shape,

58 BRITISH ENTOMOSTRACA.

opening at its lower extremity to allow the ova to escape.
The digestive tube commences a little above the man-
dibles, and is preceded by a pharynx, consisting of two
vesicles, which appear divided into cells, and present the
appearance of convolutions similar to those of the brain of
the superior animals.

The heart or dorsal vessel is exactly like what is seen
in the Chirocephalus.

The Artemise are found exclusively in salt water, and
though they do occur in salt marshes, still they are to be
found in greatest abundance in water that is very highly
charged with salt. "Myriads of these animalculi," says Mr.
Rackett, " are to be found in the salterns at Lymington,
in the open tanks or reservoirs where the brine is deposited
previous to the boiling. It attains the desired strength
by evaporation, from exposure to the sun and air, in about
a fortnight. A pint contains about a quarter of a pound
of salt, and this concentrated solution instantly destroys
most other marine animals." In these reservoirs there is
always a certain quantity of this strong brine allowed to
remain, and there these little creatures are found in greatest
abundance and in greatest enjoyment ; whilst in what are
called the sun-pans, where the brine is made by the ad-
mission of sea-water during the summer, and which are
emptied every fortnight, they are never found at all.
During the fine days in summer they may be observed in
immense numbers near the surface of the water, and as
they are frequently of a lively red colour, the water ap-
pears to be tinged with the same hue.* " There is nothing
more elegant," says M. Joly, "than the form of this little
Crustacean ; nothing more graceful than its movements.

* The fact that salt water, when highly concentrated, frequently assumes a

red colour, has been <>l'ien attributed to the presence of ^real numbers of the
Artemia salina. Indeed the cause of this red colour, \\hich \vas well knouu
Id t;ikc place !u tlie sail marches and reservoirs of salt \vatcr at Mont pellicr,
was made, some years airo, the subject of very u't'cat discussion iu France,
before the Institute. M . 1'avcii first maintained the cause to be the pre-
sence of Arii niia : M. |)ii\al'. ho\\e\er, declared that it arose from micro-
scnpie vegetables, species uf I la-matoeoccus ami ProtOrOCCllS. After a keen

ARTEMIA. 59

It swims almost always on its back, and by means of its
fins and tail it runs in all directions through the element
it inhabits. It may be seen to mount, descend, turn over,
spring forward, curve its body into the form of an arch,
and then rebound, and deliver itself up to a thousand
bizarre and capricious gambols. Their feet are in constant
motion, and their undulations have a softness difficult to
describe." The tanks or reservoirs where I have already
said they are chiefly found, are called clearers, as the
liquor becomes clear while in them, and this effect is
attributed by the workmen to this constant and rapid
motion of their feet. " So strongly persuaded," says Mr.
Rackett, " are the workmen of this fact, that they are
accustomed to transport a few of the worms from another
saltern if they do not appear at their own."

They are manifestly omnivorous, swallowing everything
that comes in their way. Like the Chirocephalus, the un-
dulatory motion of the branchial feet causes a current of
water to flow in the kind of canal formed between them,
which carries everything within reach to their mouth.
In this way we see them devouring even their own young.
" If we observe," says M. Joly, " in a small quantity of
liquid, the mother at the time of parturition, we see the
young group themselves round her body, and there is
nothing more pretty, more agile, more graceful than this
little troop. But soon the scene changes ; one, two, or
three young ones are involved in the current which the
motion of its fins causes, they pass into the gutter situated
between these organs, and from thence come to the mouth
of the mother. She at first disperses them, as being in-
convenient bodies — perhaps she may even wish to spare
them ; but soon afterwards they present themselves again,

discussion between the two above-named savatis, assisted by Messrs. Audouin
and Turpin, M. Joly set himself to discover the real cause ; and the result
of his observations is, that the red colour depends upon the presence of
myriads of a small monad, and that frequently the Artemise, from swallowing
numbers of these, partake also of the same red hue. The little creature is
called by M. Joly Monas Diii'allii, and a long account of the whole discussion
may be seen at the conclusion of M. Joly's paper in the ' Ann. Sc. Nat.'

60 BRITISH ENTOMOSTRACA.

and pressed upon by the stiff hairs which form the
branchiae, then by the papillae, lastly by the jaws, they
arrive at the mandibles, reduced nearly to pulp, and they
are swallowed as any other substance would be." Their
enemies, in such a fluid as the Artemia inhabits, are not
numerous ; but their chief foe is a small beetle, allied to
the Dytiscus, which M. Joly observed at Montpellier, and
proposes to name Hydroporus salinus. When it meets
an Artemia, it darts at it and bites it ; it then retires for
a short time, but returns to the attack again and again,
till it succeeds, by numerous bites, in killing the poor
creature, and devouring it with astonishing avidity.

The act of copulation does not appear to have been seen
by any observer except Schlosser, who says the males
seemed to be very eager to leap upon the backs of the
females, and kept tight hold of them by their prehensile
antennae. " United thus, they remain some time to-
gether, and scarce are they separated when others take their
place." The females appear to take the males even when
they have already eggs in their external ovary, as Schlosser
says he has observed the male embrace the female, in the
part where the ovary is situate, so tight as to press out
several ova; which causes him to remark : " Je n'ose de-
cider si cette action est une veritable accouplement, et si
mes insectes a bras sont les males ou les accoucheurs de
femelles, n'ayant pas, par un tres bon microscope, vu
aucnn autre chose quc ce que je viens de vous dire." It
appears, however, from M. Joly, who has isolated the
females, that one fecundation must, as in most other En-
tomostraca, suffice for more than one generation.

The same author also asserts, that the Artemiae are both
oviparous and ovoviviparous, according to the season of
the year. Before July and after September they only lay
eggs ; while during summer they generally bring forth
young. In about twenty-four hours after the young are
born or the eggs expelled, the mother changes her skin.
To effect this she rubs herself either against the sides of
I IK- vessel or against any foreign bodies she mav meet with

<_* V <J V

ARTEMIA. 61

in the water ; and in spring and summer these monltings
are of very frequent occurrence, succeeding each other at
intervals of five or six days. About fifteen days, or at
most three weeks, after the eggs are formed in the ex-
ternal ovary, they are expelled, and the mother lays three
or four times, the number at each time varying from 160
in summer to 50 only in autumn. As is the case with the
Chirocephalus, the young present, when first born, a very
different appearance from what they assume when full
grown (t. II, f. 4). They bear an exact similitude to the
young of the Chirocephalus, and the various changes
they undergo are precisely the same as those which they
experience.

1. ARTEMIA SALINA. Tab. II, figs. 2-4.

ARTEMIA SAUNA, Leach, Diet. Sc. Nat., xiv, 524.

— Desmarest, Cons. gen. Crust., 393.

Joly, Ann. Sc. Nat., 2d series, xii, 225, t. 7, 8.

M. Edwards, Hist. Nat. Crust., iii, 370.

Audouin et Payen, Ann. Sc. Nat., 2d series, Zool.

vi, 219, and x, 315.
Latreille, Regne Anirn., iv, 174.
CANCER SALINTJS, Linnteus, Syst. Nat., 10th edit., i, 634 ; 12th edit.,

i, 1056.

— Gmelin, Syst. Nat., 13th edit., 2993.

Rackett, Trans. Linn. Soc., xi, 205, t. 14, f. 8-10.
GAMMARUS SALINUS, Fabricius, Entomol. Syst., ii, 518.

Pennant, Brit. Zool., iv, 22, No. 35.
Herbst, Krabben und Krebse, i, 145.

ARTEMISUS SALINUS, Lamarck, Hist. An. s. Vert., 2d edit., v, 199.
ARTEMIS SALINUS, Thompson, Zool. Research., No. 5, 104, t. 1,

f. 1-10, t. 2.

BRANCHIPUS SALINUS, Latreille, Regne An., iii, 68, 1817.
BRINE-WORM, Schlosser, Observ. period, sur la Physique par Gautier,
pp. 58-60, i, f. A, B, 1756.

Description. — Body linear; nearly half an inch in length.
Cephalic horns in male large, flat, and two-jointed, the
lower joint carrying a tooth on its inner edge, near the
centre. Oviferous sac of nearly a quadrilateral form.

02 BRITISH ENTOMOSTRACA.

Abdomen bilobed at extremity, each lobe giving off
several short setae.

Hal). — Salt-pans at Lymington, Hants ; Schlosser,
Rackett, S. Stevens, Esq., 1848; British Museum.

ORDER II— CLADOCERA *

CLADOCERA, Latreille, Cuv. Regue Anim., iv, 151.

Burmeister, Beit, zur Naturg. der Rankcnfuss.
DAPIINIDES, Straus, Mem. Mus. d'Hist. Nat. v.
DAPHNOIDES ou CLADOCKRES, M. F.<//';/,-<1s, Hist. Nat. Crust., iii, 372.

Lucas, Explor. Sc. de 1'Algerie.

Character. — Body, except the head, which is distinct
and projecting, entirely inclosed within a carapace formed
of two valves, joined together on the back. Feet four to
six pairs ; articulations partly cylindrical, but chiefly fo-
liaceous, branchiform, and not adapted for organs of mo-
tion. Eye single, and very large. Antennae two pairs ;
inferior branched, large, and performing the functions of
swimming organs. Mandibles without palpi.

Family I— DAPHNIAD.E.

DAPHXIA, MiiUer.

DAI-IINIDES, Straus, Ainu. Mus. d'Hist. Nat., v.

DAPHNIDIENS, M. EJic<if<1.*, Hist. Nat. Crust., iii, 371 (cxclus. Lynceus).

Character. — Superior antennae generally very small ;
inferior, large, almost always two-branched. Five or six
pairs of feet, all inclosed within the valves of the carapace.
Eye single, large. Intestine straight.

Bibliographical Ilixfon/. — Swammerdam is the first
author \ve know that has taken notice of any of the

, a branch ; and Ktpac, a lioru.

DAPHNIADJ3. 63

Daphniadae, though he mentions that a species had been
observed before his time by Goedart, and named by him
"pou aquatique." * In his ' Historia Insectorum gene-
ralis,' published at Utrecht in 1669, he gives a pretty full
description of a species of Daphnia, which is evidently
the Puh'x. He calls it Pulex arboreus or arborescens, the
first part of which name has been retained, and applied
to this species, by most authors who have written since
his time. His description is not very correct in some
points ; for he says the beak is slender and pointed, and
that it is by this sharp beak the animal draws up its food,
as it were by suction, like other aquatic insects. He de-
scribes, however, its motions very well, and mentions
the animal as occurring frequently of a red colour, or
of the hue of blood. This memoir of Swammerdam is
republished in his * Biblia Naturae,' where the same
figures are also given, f

Merrett, in his 'Pinax rerum Britannicarum,' &c.
London, 1677, mentions the Daphnise, or at least is said
to intend them, by the following short description :
" Vermes minimi rubri, aquam stagnalem, colore san-
guineo inficientes, unde vulgus dira portendit."

Francisco Redi, in his ' Osservazioni utorno agli ani-
mali viventi die si trovano negli animali viventi,' Firenzi,
1684, gives three figures of a species which Muller quotes
as the Pideoc (his Pennata], but which are so very bad, that
it is difficult to make them out. He calls them by the
name of " Animaletti atjuatici." In his ' Opere,' pub-
lished at Napoli, 1687, he gives the same figures as in
the former work, and mentions them as " Tre animaletti
aquatici, che vivorno nelli acqua stagnant!, e ne' pozzi,
osservati col microscopia."

Bradley, in his ' Philosophical Account of the Works
of Nature,3 London, 1739, gives a long description of a

* I have not seen any notice of this little creature in any work of Goedart
that I have examined, and Straus remarks also that he had never been able
to procure the work in which the notice of this insect occurs.

f Vide Leyden edition, 1737.

64 BRITISH ENTO.MOSTKACA.

" wonderful insect which had but one eye," found in the
river Thames, with a " head somewhat like that of a bird,"
and " legs like the claws of an eagle ;" the large antennae
are described as " two branches, resembling the dugs of
animals," and which, he says, " we might suppose were
designed for suckling their young;" "for this insect,"
he adds, " is viviparous, which is contrary to other insects
before mentioned ; for we did not only observe the young
ones alive in the belly of the mother, but likewise saw
several of them excluded from her body." The figure
which he gives is equally good as his description, both of
them showing the force of imagination, for it is evident
this " wonderful insect" is nothing more than the
Daphnia pulex.

Trembley, in his ' Memoires pour servir a 1'histoire
d'un genre de Polypes d'eau douce,' 1744, takes notice
of, and figures, a species of Daphnia under the name of
Puceron branch u, which seerns to be the favorite food of
the polypus, as they devour them in great numbers. It
is the Daphnia pulex, and his observations on this subject,
and figures also, are quoted and copied by Adams, in his
' Micrographia Illustrata,' published in London, 1740.

Linnaeus, in his ' Systema Naturae,' 4th edition, 1744,
describes the same species shortly, under the name of
Monoodus pulex arborescens, and in his 'Fauna Suecica,'
1st edit. 1746, and f Entomologia Faunae Suecicae, 1789,
he again describes it under the name of Monoculus pulex.

Baker, in his 'Employment for the Microscope,' 1st edit.
1753, describes and figures a species, which is evidently
the J). fiidcT. lie maintains that it has two eyes, and
severely handles poor Bradley for saying it has only one,
though that is about the most correct part of his de-
scription ! He quotes Swammerdam's memoir, and retains
his name for it, as expressive of its appearance and
motion.

Joblot, in his 'Observations d'Histoire Naturelle, faites
avec le Microscope,' 1754, describes a species of Daphnia
under the name of Pan aquafu/i/e, which M tiller quotes

DAPHNIAD.E. 65

as his D. si-ma, but which Straus says is not so, but is his
D. macrocopifs. The figures which Joblot gives are very
indifferent, and it is not easy to say Avhat species they are
meant to represent.

Schceffer, in his Memoir ' Die griinen Arm -Poly pen die
geschwanzten mid un geschwanzten zackiger Wasserflohe,'
1755, describes at great length two or three species, under
the name of Geschwanzten zackiger Wasserfloh, and Un-
(jeschwanzten zackiger Wasserfloh, or water-flea with a tail,
and water-flea without a tail; and this memoir is the first
in which an attempt is made to distinguish different
species, — the various authors whom I have quoted above,
having all, with perhaps the exception of Joblot, described
only one and the same. He figures two species, the
D. pulex and siwa, and gives a sketch of the head only of
a third, which, being provided with a tail, has been quoted
by Miiller and Straus as the I), longispina. This memoir
contains a great deal of very interesting information with
regard to these little creatures, and having been partly
translated into French by Jurine, at the end of his work
on the Monoculi, it has become more available to the
naturalist. In his ' Icones Insectorum circa Ratisboniam
indiginorum,' L766, the same author figures the D. pulex
under the name of " Branchipus conchiformis primus,"
and in his ' Elementa Entomologica,' published in the
same year, I believe, he again figures it under the name of
" Branchipus conchiformis."

Poda, in his ' Insecta Musaei Graecensis,' 1761, de-
scribes shortly the same species, under Linnaeus' s name,
Monocuhs pulex, and Lederm tiller, in his 'Mikroskopischen
Gemiiths und Augen-ergotzung,' 1763, gives an in-
different figure of a species, which however is easily
recognisable as the same.

Geoffrey, in his '.Hist, abreg. des Insectes,' 1764,
gives a good many details of this genus generally, and
describes a species under the name of " Perroquet d'eau,"
which Miiller quotes as his quadrangula, but which Straus,
I think more correctly, considers the pulex.

5

6G lil'.lTISH ENTOMOSTKACA.

Goeze, in the ' Naturforscher,' 1775, describes the
same species, under the name which Swaininerdam had
given to it, the Pulcx arborescens ; and Sulzer, in his
' Abjekiirzte Geschichte der Insectcn,' 1776, gives a very
indifferent figure of what he calls Monoculus jjft/r.r, but
\\ hich is evidently the Da^lmia r<-//tla.

M filler, in his paper on the Cypris, in the ' Philoso-
phical Transactions' for 1771, has enumerated several
species of Daphuia as occurring in Norway and Denmark,
but under the general name of Monoculus. In 1776,
however, he established the genus Daplmc, in his 'Zoologize
Danicse prodromus,' and enumerated eight species, only
three of which had ever been noticed before his time.
In his ' Entomostraca,' 1785, he adds one other species,
gives figures of all the nine, and a lengthened description
of each. He changes the generic name from Daphne to
Daphnia, which latter name has been adopted by suc-
ceeding authors, and alters the specific names of two
species, though without good reasons for doing so.

De Geer, in vol. vii of his * Memoires pour servir a,
1'Histoire des Insectes,' 1778, gives a good many details
concerning this family, pointing out two or three errors
into which Swammerdani had fallen, and giving \ery
accurate descriptions of SOUK; portions of their anatomy.
He describes at length, and figures very nicely and \\itli
considerable faithfulness, four different species, two of
which, previous to this, had only been noticed by Muller,
in his ' Zoolog. Dan. prodrom.'

Blumenbach, in his ' Handbuch der Naturgeschichte,'
1770, mentions one species, they;///-",/'; and Eichhorn,
in his ' Beytrage zur Naturgeschichte der kle'mslrn
Wasserthiere,' 1781, gives a tolerable figure of the same
species.

< iinelin, in his edition of the ' Systema Natnne,' 1783,
gives all llie nine species of M filler, and adds to them the;
Monofuliix ])<'(/i<-i'//ix, which Miiller had already formed
into a genus by itself, the Poll/ /tin' mnx.

Manuel, in the 'Encyclopedic methodique,'

DAPHNIAD.i:.

67

gives all Midler's species, merely quoting his descriptions
and copying his figures.

Fabricius, in his ' Entomologia Systematica,' 1793,
changes Muller's names in one or two instances, but does
not extend the number of species ; but Schrank, in the
' Naturforscher' for that year, describes a new one.

Donovan, in his ' Natural History of British Insects,'
1803, gives an indifferent figure of a species taken when
in its young state, and which appears to be the DapUnia
vetula. He calls it Monoculus conchaceus, and makes a
few remarks upon its habits and manners, giving a
frightful picture of its ferocity and cowardice ! "By nu-
merous filaments which it darts forth," he says, * it
causes such a motion in the water as to attract unresist-
ingly the insects floating into its mouth. Thus it
exists," he concludes, " a life of rapine and destruction,
enjoyed at the expense of the lives of thousands ; and as
the objects of its ravenous disposition are defenceless, so
are they the sport of their conqueror ; the few moments
of intermission its craving appetite grants them, is occu-
pied equally in the spoil, first pressing them to death, and
then tossing them undevoured into the fluid. But should
a more powerful insect oppose him, he immediately con-
tracts his parts, and nothing more than the external
covering is open to his antagonist's violence, and he will
sooner die ignobly than oft'er the least opposition."

Latreille, in his ' Hist. Nat. gen. et part, des Crustacea
et Insectes/ 1802, enumerates all Muller's species, re-
taining his names ; and they are given in the same manner
by Bosc, in his ' Hist. Nat. des Crust, edit, de Buffon,
par Deterville/ 1802, both authors giving a number of
general details with regard to the family.

Ramdohr, in 1.805, published a detailed account of
the anatomy of two species, the sima (vetula) and longi-
spina of Miiller, in his ' Beyt. zur Naturg. einig. deuts.
Monoculus-arten.' Previous to his time, Schoefter, De
Geer, and Miiller, were the only authors who had
attempted any particular anatomical details, and this

6S BRITISH ENTOMOSTHAC A.

memoir of Ramdolir added much to what they had
done.

Lamarck, in his ' Hist. Nat. des Anim. sans Verteb.'
first edit. 1818, describes two of M filler's species, and
Samouelle, in his 'History of British Insects/ 1s 19,
gives one.

In Rees's 'Cyclopaedia/ 1819, we have all Miiller's
species ; while Leach, in his article " Crustaceology," in
the ' Edinburgh Encyclopaedia,' 1823, only mentions the
pulex.

From the time when Miiller's 'Entomostraca' appeared,
up to this period, no additions to the species had been
made; and, with the exception of Ramdohr's memoir
already mentioned, no original matter had been pub-
lished concerning the family, though, as I have already
observed, this work of Ramdolir seems to have attracted
no notice from any of the authors who succeeded him.

In 1820, Jurine's splendid work on the ' Monoc. qui
se trouvent aux Luvir. tie ( Jeneve/ made its appearance,
after the death of the talented and lamented author; it
abounds in a variety of extremely interesting information,
not only with regard to their anatomy, but to their habits

*/ O .

and manners. About the same period, an elaborate and
excellent paper on the family was read before the Academy
in Paris, by M. Straus, and published in the ' Memoires
(hi Museum, d'llist. Nat/ 18.01. To these two authors
we owe the greater part of our knowledge of these cu-
rious animals; their labours and experiments having
brought to light much informal ion with regard lo their
economy, which had escaped all the previous writers.
•hirinc describes six species, which had not been oldened
by Miiller, and Siraus thrci, llmu^li sonic of them seem
to be only varieties

Desmarest, in his work ' Coiisid. gen. sue les Crust.,'
IVJ.~), enumerates fourteen species which had been de-
scribed by the authors who had written before his time,
and which had been found in France, but adds no new

DAPHNIAD.E. 09

Gruithnisen has published a very interesting memoir
upon the Dapluiia si ma of Miiller, in vol. xiv of the
1 Nova acta Physico-Medica Academia? Cesariae Naturae

«/

Curiosorum,' part i, 1828, in which he describes at some
length the circulation of the blood, as observed by him, in
this insect. He describes two hearts, arterial and venous,
and gives a figure, much magnified, of the blood in
motion.* His figure of the creature itself, however, is not
very correct, or it is a species different from that of Miiller.
In M Ed wards' s work on the Crustacea, vol. iii, the
reader will find a description of almost all the species
known at the time of its publication, and to that we refer
him, as containing the fullest list of described species
belonging to this family.

Anatomy and Physiology, fyc. — The body is composed
of two parts, very distinct from each other : the one, much
smaller and projecting, forms the head ; the other, much
larger, and consisting of a thorax and abdomen, is con-
tained entirely within a very slender and delicate shell.
The valves of this shell are, in most of the species, per-
fectly smooth round their circumference, but on the
middle are marked, either with reticulations or deep
crossed lines, in one or two species, forming a mesh-work,
or, as SchoefFer says, they are shagreened like the skin of
a shark. They are open on the anterior margin, and
united to each other along the posterior edge, as far as
the extremity, but have no hinge, being as it were
simply soldered together, to use the expression of Goeze,
allowing the animal, however, to open and shut them to
a certain degree at will. In some species these valves
are prolonged posteriorly to a point, which, at some
periods of their growth, and in some varieties, is very
long, in others very short, and in some altogether
wanting.

In the head, the covering of which is harder than the
other portion of the shell, we distinguish the following

* L. c.,t. xxiv, f. 6.

70 BRITISH ENTOMOSTRACA.

parts : beak, antennae, eye, brain, mouth, and masticatory
organs, and part of the digestive canal.

The thoracic and abdominal portions contain the
remaining part of the alimentary canal, the heart, legs,
and organs of generation.

The beak is merely a prolongation of the hard covering
of the head ; though it is asserted by Swammerdam to be
the mouth of the animal, by means of which, being
pointed, it sucks up its food. Both De Geer and
Schceffer, however, pointed out the erroneous nature of
this assertion ; and later writers such as Jurine and
Straus, have still more clearly shown it to be wrong. At
the extremity of this beak, and a little underneath it, we
see two small projecting organs, which differ considerably
in the two sexes ; these are the superior antennas (t. VIII,
f. A, B, h ; t. X, f. 1 a, 4 ci). Schceffer, who is perhaps
the first person who noticed these, considered them as
palpi, by means of which the insect distinguished its
food. Jurine calls them " barbillons" in the female; but
Straus considers them correctly as the true antennae of
the animal, though he says they do not seem to possess
any voluntary motion. In the female they are extremely
small, and seem to have escaped Miiller's notice altogether.
In the male they are much larger, and were considered
by the last-mentioned author as the organs of generation
(t. VI, f. 1 ; t. XII, f. 1 ft). Jurine describes them very
particularly in the /Wrr, calls them "harpons," and says,
they occupy the place of the "barbillons" of the female.
They vary in the different species, and are each composed
of several articulations. They seem to assist the first pair
of feet in retaining hold of the female during the act of
copulation. On each side, upon the base of the head, are
inserted the large antenna1. They consist each of a single
joint at the base (t.VIII, f. A,f(), dividing into two branches.
This basal joint is slightly conical, generally of about the
length of the head, and very flexible at its root, having a
joint there, which unites it to the body, and facilitates its
motions in e\erv direction

DAPHNIAD.E. 71

The posterior of the two branches is divided, in most
of the species, into four articulations, and the anterior
into three. Both branches are furnished with several
long filaments or setae, which, in some of the species, as
the pule®, are beautifully feathered, or plumose, and con-
sist each of two moveable joints, which augment their
flexibility. Swammerdam calls these organs the arms,
and describes their motion very particularly, which, he
says, is threefold ; rectilinear, up and down, and to each
side ; imeqif-aJ, keeping the animal now at the bottom, and
then at the top of the water, which sort of motion he
compares to the flight of a sparrow ; and gyratory, by
which the animal moves itself in a circular manner.
De Geer also calls them arms; but M tiller, and most
other naturalists after him, call them antennae. Jurine,
however, calls them " bras ramifies," and Straus, consi-
dering them as the chief or almost only organs of loco-
motion, and acting as it were as fins, calls them rami or
"rames branchues;" they are, in fact, he says, a first pair
of feet, and act as such, as it is by means of these organs
alone that the animal moves, the other feet not serving at
all for that purpose.

The eye (t.VIII, f. A, B, c) is a spherical body, furnished
with powerful muscles, so arranged as to allow it to pos-
sess a semi-rotatory motion upon its centre, and is com-
posed of about twenty crystalline lenses, which are limpid,
and when isolated are each pear-shaped. Swammerdam
asserted that there were two eyes, which seemed to be
joined together, and several authors have adopted the
same opinion. Schoeffer, however, says there is only one,
and Miiller and De Geer repeat this, — an opinion which
has also been adopted, and proved correct by Straus and
Jurine. Eichhorn, as quoted by Straus, mistook the eye
for the stomach !

The brain, or first ganglion of the nervous system, is
situate near the eye, and is composed of two lobes, from
the superior anterior commissure of which we see, going
off to the eye, the optic nerve. The mouth (t. VIII, f. B) is

72 BRITISH KVro.MOSTRAC.A.

rather of a complicated .structure, is situate near the junc-
tion of the head and body, near the base of the beak, and
consists, according to Straus, who has given the most
correct account of this organ, of a labrum or lip, two man-
dibles, and one pair of jaws. The labrum or lip (f. B,
y, and f. c) consists of a flattish body, compressed at the
sides, and has at its extremity a large lobule, furnished
with several set;r. It is fixed 1o the posterior part of the
base of the beak, is very moveable upon its antero-supcrior
angle, and by means of powerful muscles ({'.<;,#, b, c] admits
of a considerable separation.

The mandibles (f. n) are very strong, and consist each
of a stout fleshy-looking body, which, at its superior extre-
mity, is in form of a narrow point, and articulates there
by means of several muscles with the body (f. A,/). It
descends from thence vertically to the mouth, its inferior
extremity being curved sharply inwards, so as to penetrate
into the mouth between the lip and corresponding jaw,
and terminates in a free unattached edge, which has appa-
rently neither teeth nor triturating surface, but which
when pressed closely between two pieces of glass, may he
observed to be provided with a series of about eight .small
teeth, slightly curved. These mandibles are not pro\ ided
with either palpi or branchiae, but are quite naked, and
are moved by two muscles; an abductor, which moves
them upon themselves from within outwards, and an
adductor, which brings them back to their first position,
at the sain;' tune bringing them nearer, each to the other.
The motion of tlu>e organs, when the animal is feeding,
is semi-rotatorv.

i

The jaws if. A, n, /;, and f. r) consist each of a strong-
body, somewhat rounded on the anterior surface, and
terminated b\ four strong horny spines, three of which
are prolonged into hooks, strongly curud forwards and
inuards. The fourth being small and stiaight. These
parts seem to lie constantly in motion, as if the animal
\\ere perpetually cniplo\ed ill eating. The mouth, as I
have alread} slated. \\as placed by Swannnerdam at the

JKU'HNIAD.E. 73

rxuvmity of the beak, — an opinion adopted also by
Ledmn filler. Sehceffer was the first who showed its
true situation, and l)e Geer confirmed his observations.
Schcefter describes also the two mandibles, and fancied he
likewise saw the lips, but could not make them out dis-
tinctly, from the smallness of the animal.

The digestive canal (t. VIII, f. B) commences immediately
behind the mouth, in the form of an oesophagus, which is
short, narrow, slightly curved, and stretches obliquely
forwards and upwards, terminating immediately behind
the brain, in the stomach.

The stomach (f. B, c] is in form of a large vessel, curved
at its upper part into a complete arch, nearly straight in
its course downwards through the body, and suddenly
bending up again in the abdomen. It runs almost all
the length of the animal, opening by the anus between
the first two dentated arches of the posterior part of the
last segment of the body. Immediately behind the eye,
near the cardiac extremity of the stomach, we see two
vessels (f. B, d), curved upwards, in the form of a letter S
reversed, the arch turned towards the eye ; these are
described by Sehceffer, who considers them as organs for
furnishing the necessary juices for the nourishment of the
body. De Geer says they resemble cseca. Jurine sup-
poses them to be organs proper for furnishing a juice
destined to perfect digestion. Straus at first considered
them as such also; but, upon more mature examination,
at length concluded them to be really caeca.

The body of the animal is quite free, and unattached
within the valves of the shell. It is slender and long, and
is divided, according to Straus, into eight segments ; the
first of which is the largest, and is the only one which is
attached to the valves. At the second segment the body
suddenly diminishes in vertical diameter, sinking down,
and leaving above a strong projection, formed by the first
segment. From this projection, throughout the rest of
its extent, the body is unattached to the shell, and leaves
a vacant space between it and the edge of the valves, into

74 BRITISH ENTOMOSTRACA.

which the animal deposits the eggs after laying them,
and where they remain till hatched, and ready to be
launched into the world. The seventh segment is pro-
vided with two filaments, which have an articulation about
the middle of their length, like those of the rami. In the
last segment we perceive two dentated arches, between
which is situate the anus. Beyond this it contracts in
size, and terminates in two horny hooks, the last of which
is the longest. The whole of the body, except the first
segment, as I have already said, is free and unattached,
and the insect can extend it beyond the valves at pleasure,
the two hooks at its extremity serving wrell for enabling
it to clear the interior of the valves. It seems also to clear
the feet from any particles of mud or dust adhering to
them ; and SchcefFer thinks it may also assist in bringing
before the mouth objects of food. He says also, that
perhaps the motions of the insect are partly regulated by
the strokes of this body, or tail, as he calls it, and certainly
it is in almost constant motion when the animal swims.
On the back, in the first segment of the body, wre see an
ovoid-shaped vesicle (t. VIII, f. B, i), possessed of very rapid
contractions ; this is the heart. According to Jurine, there
springs from its anterior extremity an arterial vessel, which
contracts in an opposite manner to the heart itself, curves
immediately from its origin, and goes backwards, follow-
ing the direction of the intestinal canal. Gruitliuisen
describes the heart and circulation at greater length. He
says, there are two hearts, one venous, the other arterial :
the \rnous supplies the intestines ;nid other parts of the
body with blood ; the arterial supplies the head and parts
connected with it, its brandies making the circuit of the
shell on the anterior edge, and collect ing near the pos-
terior inferior part into one large trunk, which runs along
the hack of the shell, and returns to the arterial heart
again.

The legs are li\e pairs, all differing in many respects
from each other, and serving a different purpose, than as
organs of locomotion. The first pair (t. VIII, f. K) is

DAPHNIAD^. 75

smaller than the three succeeding pairs, and is the most
simple of construction. It is situated immediately be-
hind the mouth, being inserted into the body of the
animal by the basal joint, which is broad and somewhat
fleshy. Attached to it is another joint of a triangular
shape, and having on its outer edge three small projec-
tions, each furnished with four or five long and strong
setae (analogous to the branchial plate of the succeeding
pairs). At the extremity of this joint is another very
small one, which is also furnished with one or two long
setae. All these setae are jointed at about the middle of
their length, and are not plumose.

The second pair (t. VIII, f. r) is larger than the first,
and is inserted into the body a little behind it. It con-
sists of four articulations ; the basal broad, the second
somewhat quadrilateral and flatter, with three projections
at one extremity, the two internal sending off each one
long plumose seta, and the external sending off three,
equally plumose. On each side of this second joint there
is situate another, one slightly quadrilateral, and sending
off from its external edge fifteen long setae, all jointed,
the external being much the longest and finely plumose ;
the other narrower and oblong, and furnished at its
extremity with two plumose setae. The larger of these
two may be considered as a branchial plate. In the
third pair (t. VIII, f. G), the second joint is longer than
that of the preceding pair, and sends off from its inferior
extremity two short simple setae. The branchial plate is
attached to its external face, is larger and longer than in

O O

the preceding pair, and has numerous filaments on its
free edge (Straus reckons seventy-six). The fourth arti-
culation is laiger than that of the preceding pair, is broad
and nearly quadrilateral, and sends off six long plumose
setae, four from the inferior edge, and two from its
internal side. The fourth pair (t. VIII, f. n) is similar to
the third. The branchial plate has fewer filaments
(Straus reckoning only sixty-five), and the fourth articula-
tion is more oblong, and larger. The fifth pair (t.VIII, f. i)

76 m;i iisu KNTOMOSTK.U \.

differs in many respects from tlic four preceding. It
is more rudimentary in form, and can apparently be
less readily divided into articulations. The part corre-
sponding with the branchial plate is rounded, and has
no Jilanieiits springing from its edge. Immediately above
it there arises a strong-jointed, plumose spine, which is
curved backwards upon this plate, Avhile the third and
fourth articulations are represented by finger-like pro-
cesses springing from the inferior extremity of the foot,
and sending olftwo or three plumose setae.

Jurine says this last pair of feet are not inserted into
the body of the animal, but the one is confounded with
the other on the opposite side, the junction of the two
forming the commencement of a gutter or canal, which
extends along the immediate attachment of the feet to the
mouth, where it terminates. These five pairs of feet are
in almost constant motion, even when the animal is still
and at rest, and their use at such times is to communicate
an undulatory motion to the water, from one pair to
another; thus establishing a current which enters the
shell by the anterior part, carrying the molecules, &c. in
the water to the posterior part where the gutter com-
mences, and there being driven by the vermicular motion
back again to the anterior extremity of the canal or
mouth. None of these feet are used lor locomotion. The
first and second pairs, according to Straus, are used as
organs of prehension. According to Jurine, the chief
action of the first pair is to direct the alimentary particles
brought up by the current of water, along the canal abo\e
described, into the mouth. When the mouth is opened,
says the same author, to receive the food, the motion of
all the feet, except this lirst pair, ceases, but in them, on
the contrary, it is then accelerated. The grand use of
the third and fourth pairs is respiration, being adapted
for that function by their branchial plates, which, as
De Geer had already observed, serve the same purpose
to these insects MS the gills of crabs, certain aquatic
insects, lar\:e. and fishes. The basal joints of these feet

DAPHNIAD^. 77

were considered by Schocffer as pockets filled with a
liquid destined for the reproduction of the shell at each
moulting. This opinion, however, has never been verified
by any succeeding observer.

Till Jurine and Straus described these insects, the
number even of the pairs of feet seemed undetermined.
Joblot believes there are three pairs. Schoeffer says there
are one or two pairs more. Miiller describes five pairs in
D. penned* i (fiidex], but four only in his longispina. All
the species of true Daphnia, however, have five pairs.

In the male, the first pair of feet (t. XII, f. 1 1} differs
considerably from the corresponding pair in the female.
It is more slender in form, and has a strong claw or hook
attached to the extremity of the second joint, while the
seta which springs from the third joint is very long, nearly
the length of the body, and floats outside the shell.
Jurine describes this pair of feet very particularly, and
shows the use of them to be the same as the hinge-joint
antennae in the male Cyclops, viz., for seizing and retain-
ing hold of the female during the act of copulation, the
male introducing them along with the superior antennas,
into the interior of the shell of the female, and grasping
her feet.

The male organs of generation have never been ob-
served, Midler having mistaken the superior antenna for
them ; neither have the female organs been seen, with
the exception of the ovaries. That they reside in the
lower portion of the body appears most probable, from the
description to be afterwards given of the method of
copulation, as observed by Jurine.

Straus thinks they have no external organs at all, but
that the male simply injects the semen under the valves
of the female, from which it introduces itself into the
ovaries.

The ovaries are placed along the sides of the abdomen,
as in Cyclops, and show their situation by the matter of
the eggs, in the shape of small, round, pellucid globules.
These make their appearance in the young insect after the

7s BRITISH I-.NTOMOSTKAl A.

third moulting ; and gradually after that increase in size,
lose their transparency, become continuous, and form a
dark mass on the outer edge of the intestine, partly globular
and partly elongated. At the sixth segment of the body,
the ovary communicates with the open space on the back
of the animal already described, and immediately after
the fourth moulting, we see the eggs already laid and
deposited in this space, where they remain till fully
hatched.

The animals belonging to this family are only to In-
found in fresh water, generally in ponds and ditches ;
some preferring those in which there is much of the
Icmna, or duckweed, floating on the surface, others
delighting in horseponds where cattle come to drink. In
such places they are often to be found in myriads, and
almost the whole year round; and as they sometimes
in some species assume a red colour, they have been said
to have tinged the water with the hue of blood. Swam-
merdam was the first who observed this ; he says he has
seen them in such numbers at Yincennes, as actually to
give the water of a horsepond the colour of blood; and
he quotes a friend of his in Holland, a Dr. Sehluyl, who
had noticed the same in one of the canals near his house.
This statement has been repeated by Derham, ;;; and by
many others, upon Swamnu'i-dam's authority, but not, as
far as I know, from personal obser\ation.f I have, how-
ever, frequently seen large patches of water in di IK -rent,
ponds assume a ruddy hue, like the red rust of iron, or
as if blood had been mixed witli it, and ascertained the
cause to be an immense number of the I). /i/>/i',r. The
imriads necessary to produce this ellect is really astonish-
ing, and it is extremely interesting to watch their motions.
On a snnshhn da\, in a large pond, a streak of red, a loot
broad, and ten or t\ve!\e \ards in length, will suddenly
appear in a particular spot, and this belt may be seen
rapidly changing its position, and in a very short tune

1 Physico-Theologj;, p. 364,notea; Glasgow, edit. i;r>.

f MCMVII |i<Tliap> is an c\cc|.iii.n to tins remark. tScc above, p. 63.

DAPHNIADJS. 79

wheel completely round the pond. Should the mass come
near enough the edge to allow the shadow of the observer
to fall upon them, or should a dark cloud suddenly
obscure the sun, the whole body immediately disappear,
rising to the surface again when they have reached beyond
the shadow, or as soon as the cloud has passed over.
They are very prolific, giving birth to their young a great
many times during their lives, and some of the larger
species having as many as forty or fifty eggs and upwards
in their matrix at once. According to J urine, in June
the young ones begin to have eggs, about ten days after
their birth, and it is probable they continue to produce
all the summer through at frequent intervals. The males
are very few in number, compared with the females, and
are only to be met with at certain seasons, generally, as far
as my observation goes, in autumn. From this circum-
stance, Schceffer and others have considered them as her-
maphrodites ; and Sulzer (as quoted by Straus), though
he oppugns this opinion, gives a more singular one still,
believing that a copulation might take place with the
young before they see the light of day ! These authors
had never seen the males, nor ever witnessed the act of
copulation. Miiller and others, however, detected the
male, and witnessed the act ; and it is now clearly ascer-
tained that one single copulation is sufficient not only to
fecundate the mother for her life, but all her female de-
scendants for several successive generations. This was
observed by SchoefTer, who followed them up to the fourth,
by Straus to the fifth, and by Jurine to the sixth ; the hitter
observing that he thinks it probable it might extend in
some species to the fifteenth generation. Extraordinary
as this may appear, I have further found that the young-
produced from the ephippial eggs are also fecundated by
this one copulation, and have progeny ; and that their
young again also produce eggs without the intervention of
the male. I have followed up the successive generations,
as far as the fourth, in the Daphnia? born in the usual
manner, and as far as the third, in those born from ephip-

ENTOMOSTUA< \.

])i;il eggs ; and have found, from repeated experiments,
that those Daphniae which had ephippia became loaded
with eggs soon after they had thrown off these organs,
and had progeny again, without the intervention of males ;
and that the young so born from these Daplmia-, which
had tin-own oil' their ephippia and become pregnant, were
also independent of the access of the male, and became
mothers in the same manner as the young of oth'T
Daphniae.

November 29th, I isolated a I), pnlr.r with an ephip-
])inm ; 30th, ephippinm is thrown on"; December 4th,
Daphnia has eggs ; 8th, young ones are born ; Uth, the
mother, having been removed from the young imme-
diately after their birth, was found to ha\e eggs again :
1 (ith. young ones born ; 20th, lias eggs again ; .0 Ith, young
ones born; 25th, has eggs again; .January (ith, young
born — mother has esrcrs in ovarv again ; Mth, vounu: born

• " »- o *

— mother again has eggs ; 22d, young born ; February 1 st ,
has eggs again ; 8th, young born.

On the N!I December isolated one of the young born
from the subject of last series of observations on the 30th
November. On the 21st Decembei she was found to
Ii;i\e e..-gs ; 28th, young born; 2!)th, has again eggs;
January (.)th, young born — mother has eggs again ; 2 1th,
young born ; 25th, has eggs again ; I'Ybruary 1st. young
horn — mother has eggs again; 9th, young born ; •J'/th.
has eggs again ; .March sth, young born.

In both of these experiments the young were always
removed from the vessel in which the mother was kept as
soon as born.

On the 2d November I placed several ephippia in a
glass of clear water. On the Kith two young l)aphni;e
were born — -isolated one of them; December 12th, this
Daphnia has given birth to several young, and has eggs
again ; 1 sth, has again gi\en birth to several young ; 1 Dili,
has eggs again ; 2 I th, \oimg born ; 25lh, has again eggs :
Januan (ith, young born ; 25th, alter two several moult -

DAPHNIADJE. 81

ings without producing eggs, has again become pregnant ;
February 1st, young born.

On the 5th December isolated a young Daphnia born
from an ephippium; January 18th, it has given birth to
young; 19th, isolated two of these, both females; February
8th, both of these have given birth to young ; isolated two
of them.

I was at this period obliged, from circumstances, to
suspend my observations ; but the above experiment is
sufficient to prove the fact, that the young born from an
ephippial egg produce young, which in their turn become
mothers without the intervention of the male. According
to Jurine, who has watched the act with great care, the
following is the manner in which copulation is effected.
When the male attacks the female for this purpose, he
springs upon her back, and gradually descends, till he
reaches the inferior edge of her shell, and finds himself in
a position where the open edges of the shell are opposed
to each other. He then introduces the antenna? and first
paii- of feet into the interior of her shell, and with them
embraces her feet. Thus fixed, he curves up his tail so
as to touch the female, who at first is much agitated, but
after a little time pushes out her tail also. They touch
each other, and then they separate, the male at the time
of touching having been agitated with convulsive motions.
The eggs are first to be seen in the shape of small, round,
pellucid globules, which mark the situation of the ovaries
placed along the sides of the intestine. These soon lose
their transparency, become enlarged and continuous, and
form a dark mass on the outer edge of the intestine,
partly globular and partly elongated. The creature now
changes its covering, and shortly afterwards the eggs quit
the ovary, and take their place in a spherical form in the
open space on the back of the animal, where they remain
till the time of expulsion, quite free and unattached . At
first they are quite round, and appear to consist internally
of little globules, like air-globules. The shape then alters
a little, becoming oval, and the globules augment in

6

BRITISH EXTOMOSTRAC A.

mini her, but as yet no trace of any part of the body is
recognisable. A little afterwards we see a black spot in
the centre, which is the eye, and is the first organ visible.
The other organs then begin to show themselves, but it is
not till near the end of the fourth dav, or ninety hours

t/ ' V

after laying, that motion is perceptible. At the end of
the fifth day the young arc launched into open day. They
are from the first exactly like the parent, undergoing no
metamorphosis, but merely differing in the less complete
development of parts. In the case of the I). /Wr,r, the
young are born with the prolonged spine at the extremity
of the valves curled up within the shell ; and very shortly
after birth, a few seconds after they have begun to move
about in the water, this tail may be seen to spring forth
with a sudden jerk, and assume its natural position. The
setae of the large antennae or rami may also be seen to
spring out in the same sudden manner, having been appa-
rently folded up along the stem. During tlie time this
process is going on, the little creature may be seen fre-
quently stopping in its career through the water, bending
up its body within the shell, and pushing it quickly out
again beyond its edges, while the large antennae are bent
downwards, so as to enter the interior of the shell, where
they are embraced by the feet, and quickly drawn through
them, so as to catch the ends of the setae, and raise them
up. At this time the motions of the animal are exactly
like those of the common house-fly, when it stops to clean
its wings and feet. This sudden evolution of these parts
is attempted to be accounted for by Straus, from the in-
stantaneous flow of blood into these organs. In a verv
short tune afterbirth the young animal is exactly like the
parent, and gradually increases in size, till the shell be-
comes too small to hold it, when it throws it off, and
comes forth with a ne\v and a larger one.

This process of moulting is very curious, and all-im-
portant for the life of the animal. The intervals bet ween
them vary according to the season of the vear, being
shorter in summer than in cold weather. Schccffer says

DAPHNJAD^. 83

it takes place in the young every two days, which agrees
very nearly with Jurinc's experiments, performed in the
month of June. In winter the intervals are somewhat
greater. In the month of December I found, when kept
in a vessel in my room, the intervals thus : December 8th,
young one born ; 12th, moulted for the first time; 14th,
moulted a second time; 17th, moulted a third time;
21st, moulted a fourth time, and has eggs ; 29th, moulted
a fifth time; January 9th, moulted a sixth time; 19th,
moulted for the seventh time. In a young D. pulex, born
from an ephippial egg, the intervals were as follow :
December 5th, young one born ; 13th, moulted for the
first time; 17th, moulted a second time ; 24th, moulted
a third time ; January 3d, moulted a fourth time, and has
eggs ; llth, moulted a fifth time ; 18th, moulted a sixth
time.

Each time it moults it increases in size, the moulting
being evidently necessary for the gradual growth of the
animal. The process does not seem to stop, however,
when it has acquired its full growth, but, as far as I am
able to judge, continues during its whole life, even long
after it has gained its full size. The shell of the adult
Daphnise, when in very stagnant waters, soon becomes
overgrown with moss or parasitic infusoria, and thus
the animal's motions become much impeded, and at
last entirely destroyed ; the moulting, therefore, seems to
be necessary in the full-grown animal for the preservation
of its life, for weak or sickly individuals may be seen
frequently so overgrown with Confervse, &c., that motion
and life are both soon arrested, the little creature appa-
rently not having strength enough to throw off its exuviae.
At the fourth moulting* the young insect has eggs, which
are deposited in the open space on the back, almost im-
mediately after the old shell has been cast off. The time
that the eggs remain there varies according to the season
of the year. In summer, according to Jurine, three days ;

* Straus says after the third ; Jurine, generally between the third and
fourth. I have invariably found it to be immediately after the fourth.

84 BRITISH ENTOMOSTRACA.

according to Straus, from four to six. In winter I have
found the interval between the eggs being deposited in the
open space and the young being born to be eight days, as
may be seen in the experiment detailed above. Moulting
takes place every time after the young are born ; and
generally within a very short period after the change has
taken place, eggs are again deposited. Occasionally, how-
ever, this does not take place, and then the animal remains
without eggs for a space of time equal to that of carrying
the eggs, when she moults again, and then has eggs.
Straus says, that the young of the same laying are, gene-
rally speaking, all of one sex, the two sexes being seldom
found together in the same birth. He also says that the
Daphnia3 cease to produce at the approach of winter, and
to change their skin, and that they die before the com-
mencement of frost. This does not accord with my ex-
perience, having found them in considerable numbers,
producing young and moulting as late as the month of
December, after both frost and snow had taken place.
Indeed, I have found them as late in the season as Feb-
ruary, though not in great numbers ; but about that time
they seem to disappear, and perhaps in a severe winter
they perish earlier, as young individuals only are generally
to be met with in the spring.*

At particular seasons the Daphnise may be found with
a dark opaque substance on the back of the shell. This
is what I have so frequently mentioned above as the
ephippium, so called by Miiller, from the resemblance
it bears to a saddle. This author was the first who
took notice of this curious appearance ; but though he
describes it well, and lias given an accurate representation
of it, he does not give any opinion upon the cause or use
of the formation. Juriiu- next noticed it; he describes
it carefully, traces its gradual formation from matter con-
tained in the ovary, and states it as his opinion, that it

* Tn a mikl season they may lie found all the winter through ; and even in
the lieginnmg <>f March I have found the D. }>//le.r in great abundance and
of large size, many also with ephippia.

DAPHNIAD.E. 85

is a disease these little creatures are subject to, the effect
of which is to arrest their future fecundity. Straus,
however, has been more fortunate in his observations
upon this anomalous production, and has proved it to
be a substance containing two eggs, destined, he says, for
the future generations of the species in the spring, these
eggs resisting the cold of the winter, which proves fatal to
the perfect animal. He says they are generally to be met
with in the months of July and August. Jurine men-
tions them as occurring as early as May, and I have found
them in abundance upon the animals as late as the month
of November. The description of its formation, given
by Jurine, is very accurate, though he is wrong as to its
physiology.

After the third moulting has taken place, we may see a
green matter in the ovaries, which differs both in colour
and appearance from that of the eggs. After the fourth
moulting this green matter passes from the ovaries into
the matrix or open space on the back, and there spreading,
forms the ephippium. At first it is of a grayish colour,
and some hours after becomes of a black hue. When
examined by the microscope, it appears of a dense texture,
composed of a sort of network of hexagonal cells. In the
centre of this opaque mass we see one or two round or
rather oval bodies, called ampullae by Straus, who says
they are capsules, opening like a bivalve shell. In each
of these bodies is contained an ovum, covered with a horny
shell, by which means they are protected from the severity
of winter, and enabled to resist an intensity of cold which
kills the parent.

At the fifth moulting the animal abandons the ephip-
pium, which floats on the surface of the water, and re-
mains, with the two eggs inclosed, till next spring, when
the young are hatched by the returning warmth of the
season. " These two kinds of eggs," says Straus, " pro-
duced by the same animal, offer a very singular example
in the history of animals, and show with what wisdom
nature provides for the preservation of her smallest crea-

86 BRITISH ENTOMOSTRACA.

tures." Straus says he lias frequently hatched the young
from these ova by suddenly bringing them into a warm
temperature. I have, by repeated experiments, ascer-
tained the truth of Straus's statement, and frequently
witnessed the young hatched from these ephippial eggs,
by keeping them in my room in a genial temperature.

On the 2d of November I took several ephippia, which
I found floating on the surface of a saucer full of water,
containing numbers of D. pulex, many of which had
ephippia attached to them, and placed them by themselves
in a glass of clear water. On the 10th, two young ones
were born ; 16th, one more born ; 29th, two more born ;
21st, one more ; and 23d, two more born.

November 29th, I took several ephippia from the same
saucer as the last, and isolated them in the same manner.
December 5th, three young ones are born ; 6th, two more ;
8th, two more ; 10th, two more; and on the 16th, one
more, were born.

On the 19th of November I isolated a Daphnia, with
the ephippium attached ; 21st, it has thrown off the
ephippium ; December 5th, one young one is born from
the ephippial eggs. I have repeatedly performed the
same experiment, and have always found similar results.
The young from these ephippial eggs do not differ from
those born naturally, unless that they are perhaps a little
longer in coming to maturity.

In a young D. pulex, born naturally on the 8th of
December, it moulted the first time on the 12th, or four
clays after birth ; on the 21st, or thirteen days after birth,
it moulted for the fourth time, and had eggs ; whilst in a
young one of the same species, born from an ephippial
egg on the 5th December, the first moulting took place
on the 13th, or not till eight days after birth; and the
fourth, when she had eggs, not till the 3d January, or
twenty-nine days after birth. Tho periods between each
moulting are also longer than in the others.

It has been asserted, as I have mentioned above, by
Jurine, that these ephippia are the consequences of a

DAPHNIAD^E.

87

disease these animals are subject to, and that they have the
effect of arresting their future fecundity. From the ex-
periments I have detailed above, and from similar ones
made previously by Straus, it is evident that they are not
a disease, and that instead of being so, they contain ova
of a particular nature, destined to outlive the severity of
the winter, and to perpetuate the species, which would
otherwise perish altogether. From some experiments
which I instituted upon this subject, I also found that
Jurine is wrong in asserting that they arrest the future
fecundity of these little creatures.

On the 29th December I isolated two specimens of
D. pulex, with their ephippia attached. On the 30th
both had thrown off their ephippia, and both had moulted.
Upon close examination, I found that on the shell where
the ephippia were situated, there was left a mark corre-
sponding to its figure, and a scar or deeper mark was
visible where the ampulla containing the ova had been.
In the ovaries were to be seen the transparent globules or
first appearance of the ova. On the 4th December both
had eggs lodged in the matrix, and on the 8th the first
family were born.

I watched the further progress of one of these Daphniae.
On the 16th December she had given birth to a second
family, but did not moult till the 20th, when she again
had eggs in her matrix ; and on the 24th she gave birth
to a third family. On the 6th of January she had given
birth to a fourth family ; January 14th she has given birth
to a fifth progeny ; January 22d she has had a sixth family.
One or two other experiments, with similar results, prove
satisfactorily that the assertion of Jurine is incorrect.

The motion of most of the species belonging to this
family is chiefly by short bounds through the water, the
most important organ producing the motion being the
large antennae. Such, in particular, is the manner of
swimming of the D. pulex and rotunda, &c.

Many of the Entomostraca have the faculty of returnin
to life after having been completely dried. Sc~

88 BRITISH ENTOMOSTRACA.

instituted a series of experiments upon this subject, with
regard to the Daphniae, and his results are, that after
having exposed the insect with eggs in the matrix for a
considerable time to a dry atmosphere, and then replacing
it in water, the eggs did not lose their vitality, but were
after a time hatched as usual. Sulzer, as quoted by
Straus, says the parents return to life also ; but in the
experiments reported by Straus, he never found either the
mother or the eggs recover their vitality. The food of
these animals, according to Straus, consists of vegetable
matter, and not animal ; but I have no doubt that they
are carnivorous, as I have invariably found, that of two
groups placed in separate vessels of clear water, the one
having only particles of vegetable matter placed beside
them, while with the other there were also introduced in-
fusorial animalcules, the latter were much stronger and
more active, and throve better than the former. (Vide
supra, p. 6.)

I have divided the animals belonging to the family
Daphniadae into two sub-families, according to the number
of their feet and the construction of their large antennae
or rami.

DAPHN1NA.

Five pairs of feet. Inferior antennae, two-branched ;
one branch divided into four, the other into three articu-
lations.

1. DAPHNIA. — Head produced downwards into a more
or less prominent beak. Superior antennae exceedingly
small, one-jointed, and situated under the beak.

2. MOINA. — Head rounded and obtuse. Superior
antenna; of considerable length, one-jointed, arising from
the front of the head, near the centre.

3. MACROTHRIX. — Head terminating anteriorly in a
sharp beak, directed straight forwards. Superior an-
tennae of considerable size, one-jointed, and hanging
pendulous from the beak.

DAPHNIA. 89

4. BOSMINA. — Head terminating anteriorly in a sharp
beak, directed straight forwards. Superior antennae long,
many-jointed, and projecting from the extremity of the
beak.

SIDINA.

Six pairs of feet. Inferior antennae two-branched ; a
row of spinous filaments springing from the edge of larger
branch. Superior antennae of moderate size.

1. SID A. — One branch of inferior antennae with three,
the other with two articulations.

2. DAPHNELLA. — Both branches of inferior antennae,
consisting each of only two joints.

DAPHNINA.

Genus 1 — DAPHNIA.

DAPHNE, Mutter, Zool. Dan. Prodrom.
DAPHNIA, Mutter, Entomostraca.

Straus, Desmarest, Latreille, Lamarck, Bosc, Leach, M. Edwards,&c.
MONOCULUS, Lmnteus, Poda, Blumenbach, De Geer, Jurine, Manuel, &c. &c.

Character. — Head produced downwards into a more or
less prominent beak. Superior antennae exceedingly
small, one-jointed, and situated under the beak ; inferior
antennae large and powerful.

1. DAPHNIA PULEX. Tab. VI, figs. 1-3, male and female ;
Tab. IX, fig. 5, jun. ; Tab. VII, figs. 3, 4, Var. lon-
gispina; Tab. XI, figs. 3, 4, 5. Var. magna.

MONOCUIATS PULEX, Linnaus, Syst. Nat., 10th edit., i, 635, No. 4,

1758 ; 12th edit., i, 1058, No. 4.
Gmelin, Syst. Nat., 13th edit., i, 2999, No. 4.
Poda, Ins. Mus. Grsecens., 124.

— Mutter, Faun. Insect. Friedrichsdalens. 95.

— Blumenbach, Haudbuch der Naturg., 399.
Manuel, Enc. meth., vii, 722, No. 15, t. 265,

f. 1-4.

— Fabriciris, Entomol. Syst., ii, 491.

90 BRITISH ENTOMOSTRACA.

MONOCULUS PULEX, Leac/i, Encyc. Brit., art. Entomol.

Ji/i-iiif, Hist, des Monoc., 85, t. 8, f. 1-2, t. 11,

f. 1, 3, 5.

( Busier, Tab. Klcmeut., 455.

DAPHNE PULEX, MSller, Zool. Dan. Prod., 199, No. 2400, 1776.
DAPIINIA PULEX, Latreille, Gen. Crust, et Ins., i, 17; Hist. IN. d.
gen. et part, des Crust., iv, 223 ; Rcgne Aniin.
Cuv., edit. 2d, iv, 171.
Lamarck, Hist. Nat. des An. s. Vert., edit. 2d, v.

181, No. 1.

Samoitelle, British Insects, 80.
Straus, Menu du Mas. d'Hist. Nat., v, t. 29,

f. 1-20.
Desmarest, Consid. gen. sur les Crust., 372, t. 54,

f. 3, 4.
Jiaifd, Ann. Nat. Hist., i, 254, t. 9, f. 1-12 (for

details).

M. l'.'lir(i,-,1s, Hist. Nat. des Crust., iii, 37'J.
Guerin, Icouograpli. Crust., t. 33, f. 1.
0. Fi/ltrii-h/n, Faun. Greenland., 203.
Leach, Edin. Encyc., vii, art. Crustaceol.
DAPHNIA PENNATA, MiiHcf, Eutomost., t. 12, f. 4-7.

Bosc, Man. d'Hist. Nat. des Crust., ii, 280.
Schrank, Faun. Boic., iii, 264.
MOSOCULUS PULEX ARBORESCENT, L'nntrrus, Syst. Nat., 4th edit., 96;

Faun. Suec., 344.

PULEX ARBORESCENS, Sifniiimri-iltim, Hist. Ins. Gen., 76, 1. 1, f. «, b, c;

Biblia Naturae, 86, t. 31, f. 1-3.
Goczc, Naturforscher, pt. 7.
M<JNOCULUS PULEX RAMOSUS, l)e Gcer, Mnii. pour servir a 1'Hist.

Ins., vii, 442, t. 27, f. 1-4.

D.VPIINIA RAMOSA, Koch, Dcutsch. Crust., h. xxxv, t. IS.
DAIMIXIA MKHIA, Knrli, Dcutsch. Crust, h. xxxvii, t. 1.
DAPHNIA i:riiirn \i \, A'-/f//, Dcutsch. Crust., h. xxxv, t. 16.
PUCERON BRANCUU, Tri'ml,!,-;/, Mnii. pour servir a 1'Hist. d'uu Geu.

de Polypes d'cau douce, 92, t. 6, f. :'. p, k I'. 1 1.
WATER- i u: v WITH URANC IIEU HUHNS />///>•/•, Knip. fur Micros., 302,

t. 12, f. 14.
Pou AUI \THii i:, ./<>/,/i>(, Oliscrv. d'11 1st. Nat., i, pt. 2, 105, t. 13,

f. l',U, U.

LE l'i:i;iiiMii !•.•!• D'KAI:, G«,/r;i/, Ilisl. alin'.i,'. Ins., ii, 655, No. 1.
\ i I;MI;S MINIMI i;i r.i;i. ,!/-/•/>//, 1'inax Her. Nat. I'.rit., 207.
\MMAI.I: in AQUATICI, Rtidi, Ossorvax.ioiii, t. Hi, I". 5;

i i|KTP, ii, (. 16, f. 5.

DAPIINIA. 91

MONOCULUS, Bradley, Phil. Account of Works of Nat., 202, t. 25, f. 5.
LE FUCERON VEKDATRE, Ledermiiller, Mikroskop. Gemiiths. Augen-

ergotz., 146, t, 75, f. 2.

Tar. «. DAPHNIA LONGISPINA, Mullet; Eiitomost., 88, t. 12, f. 8-10.

Latreille, 1. c., iv, 226.
Bosc, 1. c., ii, 283.
Ramdohr, Beyt. zur Naturg. ein. Deutsch.

Mouoc. arten, 24, t. 7.
Lamarck, 1. c., v. 127.
Straus, 1. c., t. 29, f. 23-4.
Desmarest, 1. c. 372.
If. Edwards, 1. c., iii, 380.
Koch, Deutsch. Crust., h. xxxv, t. 1 7.
MONOCULUS LONGISPINUS, Fabricius, Ent. Syst., ii, 492.

Manuel, 1. c., 718, t. 265, f. 5-7.
De Geer, 1. c., vii, 442, t. 27, f. 1-4.
Schceffer, Die griin. Arm-Polyp., 59, t. 2, f.l.

Far. /3. DAPHNIA MAGNA, Straus, 1. c., t. 29, f. 21-2.

Desmarest, 1. c., 373.
M. Edwards, 1. c., iii, 380.

The shell or carapace is oval, quite transparent in
general, and very finely striated on the anterior and
middle portions of the valves, the striae crossing and inter-
lacing with each other. Sometimes it is of a red colour.
The lower extremity of the valves terminates in a sharp
spine, which is serrated on its edges. This spine varies
in length ; in general, in the adult, being short and
straight ; in some it is a prolongation of the dorsal
margin, in others it is directly in the centre, but in the
young, and in var. a, it is long, and slightly bent back-
wards. The head is large, rounded on the upper and
anterior portion, and produced lower down into a sharp,
pointed beak. The superior antennae are exceedingly
small, consisting of only a slight protuberance, and five
or six short setae. The inferior antennae are very large.
The anterior branch consists of four articulations, the first
of which is very short. From the extremity of the third,
issues a long filament ; and from the apex of the fourth,
three others arise, of equal length. The posterior branch

92 BRITISH ENTOMOSTRACA.

has only three articulations, all of nearly equal length.
From the first and second a long filament is sent forth,
and three others spring from the extremity of the third.
These filaments are all beautifully plumose, and have a
joint at about the middle of their length.* The sixth
segment of the body has four projections issuing from it,
the first being prolonged, and bent upwards.

The male is much smaller than the female. The su-
perior antennae are much larger, and spring from under
the beak, instead of from the beak itself. The inferior
extremities of the valves are more densely serrated than
in the female. It is comparatively rarely to be met with.

Hob. — In almost all pools, and ditches of standing
water, round London, &c. ; common from April to
January. Belfast, May 1849, W. Thompson, Esq.

2. DAPHNIA PSITTACEA. Tab. IX. figs. 3, 4.

Valves of shell, or carapace, oval, transparent, nearly
colourless. The head is large, somewhat square-shaped,
and the anterior part is beaked like the beak of a parrot.
The superior antennae are short, but larger than in pre-
ceding species, and rise from the under surface of the
beak. The posterior angle of the shell terminates in a
long, sharp point, which is closely serrated on both sides.
The margins of the valves are also closely serrated over
the greater part of their length, the seme of dorsal margin
extending to near the commencement of the head. The
filaments of the antenna? and abdominal lobe are finely
plumose. The eye is large.

This species bears considerable resemblance to the
D. pulex, and at first sight may be easily confounded
with it. Upon close examination, however, the form of
the head, and the serrated dorsal margin, distinguish it

* The number of (he artieiilatioiis, their relative si/.e, and the number and
distribution of the filaments of these antenna', are the same in till the species
of (he genus Daplmin.

DAPHNIA. 93

very readily. I procured a few specimens in the begin-
ning of April, along with the pulex. All those I detected
had the ephippium upon them, and, two or three which
I isolated, died very soon after throwing it off. I re-
moved, however, these ephippial ova, placing them in a
glass of water by themselves. In about twelve or fourteen
days, I had the satisfaction to find the young born from
one of these exuviae ; and upon careful examination, I
was perfectly satisfied of this being a distinct species, as
these young animals resembled, in every respect, their
parent. Later in the season, I had opportunities of ob-
taining adult females with ova, and witnessed the young
hatched. These perfectly resembled the adults, in the
shape of the head, &c.

Hob. — Pond on Blackheath ; April, June, Sept. 1848.
3. DAPHNIA SCHCEFFERI. Tab. VII, figs. 1, 2 ; Tab. VIII,

figS. A 1.

GESCHWANZTEN ZACKIGER WASSERFLOH, Schceffer, Die grtinen Arm-
Polyp., t. 1, f. 8, 1755.
BRANCHIPTJS CONCHIFORMIS PRIMUS, Sckaffer, Element. Eutomol.,

t. 29, f. 3-4.

DAPHNIA PULEX, Koch, Deutsch. Crust., h. xxxv, t. 15.
DAPHNIA, Rymer Jones, Outlines of Animal Kingdom, 330, f. 155.
Eichhorn, Beytragezur Naturg., t. 5, f. H (after Schoeffer).

Carapace nearly circular, prominently convex in the
centre, and sharply keeled round the circumference pos-
teriorly. Inferior extremity terminated by a long and
sharp spine, directed backwards, and finely and closely
serrated ; the serrations extending upwards along the
back, for more than two thirds of its extent posteriorly,
and throughout the whole anterior margin. It is quite
transparent, of a whitish colour, and shows the body dis-
tinctly through it, which in some specimens, in particular
localities, is of a fine, light-red colour. The whole surface
is finely reticulated, the reticulations being small, and
closely set. Near the anterior margin, and at the upper

94 BRITISH ENTOMOSTRACA.

part, the carapace is marked with a series of circular, flat-
looking canals (t. VII, f. 1 «), which resemble very much
the canals described on the carapace of the A pus, and
which probably serve the same purpose.

The head is very small, compared with the size of the
animal, flattened on the summit, and straight on its front
margin, which terminates in a short, projecting beak.
On its posterior surface it is marked near the edge with
a strong ridge, which appears to commence just above the
eye, and runs down to immediately above the heart ;
while a similar elevated ridge seems to encircle the root
of the antennae.

The eye is of a moderate size, but smaller in propor-
tion than in fos> puleae.

The inferior antennae are small, compared with the size
of the animal, the filaments being finely and densely plu-
mose, but the antennules are well developed, compared
with the 2^Jex; consisting of a short tubercle, which sends
off several short seta?.

The sixth segment of the body sends off five projec-
tions ; the two posterior being in the form of long spurs,
and curved, the points reaching backwards and upwards,
the other three being short and obtuse, all finely serrated.
The fifth sends off two filaments, which are much shorter,
proportionally, than in the two preceding species, but
finely plumose.

The abdomen is rather long, broad at the upper part,
rather deeply sinuated at about half its length, and narrow
towards the extremity. It is beset on the under edge
with about fifteen teeth, the siniiation being free from
them, and is terminated by two long, curved spines.

The young are very numerous, and I have sometimes
counted upwards of thirty born at one accouchement.
When the ova arc in the ovarium, and even when the
young are considerably developed, they present a beautiful,
green-coloured mass, showing through the transparent
carapace.

This is by far the largest species of the family I have

DAPHNIA. 95

yet seen, being about the fifth of an inch in length, and
two lines broad. Their motion through the water is pe-
culiar, being a tumbling, heavy sort of movement, and,
when seen in their native ponds, they seem to keep near
the bottom. When at the bottom of the vessel in which
I kept them, I have frequently seen them turn head-
over-heels, throwing a regular summersault, ten or a
dozen times in succession. The males I have never yet
seen.

The specimens I first procured from Bexley were mostly
all grievously infested with the wheel polypi, which had
settled in numbers upon all parts of the shell. I placed
them, however, when I reached home, in clear fresh water,
and shortly afterwards they moulted, or changed their
carapace, and thus got rid of their tormenting guests,
which afterwards, I have no doubt, became their food.
Previous to this change of carapace, the terminal spine
was very long, but I observed that in the new shell it
became shorter, and more obtuse.

Hob. — Pond on Bexley Heath, Kent, August and
September, 1849. Pond at Norwood Green, Middlesex,
September 1849.

4, DAPHNIA VETULA. Tab. X, figs. 1, la.

DAPHNE VETULA, Midler, Zool. Dan. Prod., No. 2399, 1776.
DAPHNIA VETULA, Straus, Mem. Mus. Hist. Nat., v, t. 29, f. 25-6.
Baird, Ami. Mag. Nat. Hist., i, 255, t. 9,f.l3.
DAPHNIA SIMA, Mutter, Eutomostraca, 91, t. 12, f. 11-12, 1785.

Latreille, Hist. Nat. gen. et part. Crust., iv, 228.

Bosc, Hist. Nat. Crust., ii, 280.

Ramdohr, Beytr. zur Naturg., 18, t. 5-6.

Gruitlmisen, Nov. Act. Pliys. Med. Acad. Caesar. Na
Cur., xiv, pt. 1, 399, t. 24, f. 1-6.

Desmarest, Cousid. gen. Crust., 373.

Lamarck, Hist. An. s. Vert., v, 182.

M. Edwards, Hist. Nat. Crust., iii, 382.

Koch, Deutsch. Crust., h. xxxv, t. 12.

4I &

96 BRITISH ENTOMOSTRACA.

MONOCULUS SIMUS, Gmelin, Syst. Nat., 13th edit., i, 3000, No. 25,

1788.

Manuel, Eiicyc. meth., vii, 723, No. 18.
Jurine, Hist. Nat. Monoc., 129, t. 12, f. 1.
MONOCULUS LJEVIS, Fabriciiis, Ent. Syst., ii, 492, 1793.
MONOCULUS EXSPINOSUS, De Geer, Mem. pour servir ;\ 1'IIist. Ins.,

vii, 457, t. 27, f. 9-11, 1778.

MONOCULUS CONCHACEUS, Donovan, Nat. Hist. Brit. Ins., i, 15, t. 5,f. 1.
UNGESCHWANZTER-ZACKIGER WASSERFLOH, Schaffer, Die griiu. Arrn-

Polyp., 229, 1. 1, f. 9.

MONOCULUS NASUTUS (?), Jurine, 1. c., t. 13, f. 1.
MONOCULUS PULEX, Sulzer, Abgekurzte Geschickte der Insecten, 266,

t. 30, f. 10 e.

DAPHNIA CONGENER, Koch, Deutsch. Crust., h. xxxv, t. 13.
DAPHNIA EXSPINOSA, Koch, 1. c., h. xxxv, 1. 11.

The shell or carapace is ovate, transparent, and smaller
than in any of the preceding species. It is striated; the
striae being deep, and sometimes crossing, so as to pro-
duce a reticulated appearance, especially on the anterior
margin, which is furnished with numerous long cilia. The
posterior extremity is rounded, slightly serrated, destitute
of the spine which marks the preceding species, and is
obliquely truncate anteriorly.

The head is obtuse, much smaller than \\\pulc,v, and
the beak less projecting. The superior antennae are
larger than in any of the preceding species, consisting of
a stout joint, arising from under the beak, and five short
setae. The filaments of the large antenna? are jointed
and plumose, but not so decidedly as in the preceding.
The sixth segment of the body has about throe small pro-
jections from the posterior portion ; and near its upper
part one longer, like a spur, slightly curved upwards,
which serves to hold up, or keep back the ova from falling
down beyond a certain distance.

Jlalj. — Ponds and ditches round London, &c. ; common
throughout the summer and autumn. Belfast, May 1849,
W. Thompson, Esq.

DAPHNIA. 97

5. DAPHNIA RETICULATA. Tab. VII, fig. 5; Tab. XII,
fig. 1, male, and fig. 2, var. guadrangida.

MONOCULTJS RETICULATUS, Juriiw, Hist.Nat. Monoc.,139, t.14, f.3, 4.
DAPHNIA RETICTJLATA, Desmarest, Cons. gen. Crust., 374.

M. Edwards, Hist. Nat. Crust., iii, 381.
Baird, Trans. Berw. Nat. Club, ii, 148 (not

Ann. Mag. Nat. Hist.)

DAPHNIA VENTRICOSA (?), Koch, Deutsch. Crust., h. xxxv, t. 21.
DAPHNIA QUADRANGULA, Mutter, Entomost., 90, t. 13, f. 4.

Latreille, Hist. Nat. Crust., iv, 227.

MONOCTJLUS'Q,UADRANGULA, Gmelin. Linn. Syst. Nat., 2999, No. 24.
MONOCULTJS QUADRANGULARIS, Manuel, Enc. meth., vii, 723, No. 15.

t. 265, f. 8-9.
MONOCULUS QUADRANGULTJS, Fabricim, Ent. Syst., ii, 492.

The shell or carapace in this species is of a rounded
oval shape ; the dorsal edge being slightly round, and the
anterior bulging out a little inferiorly. The surface is
covered with a complete meshwork of small hexagonal
cells ; and the inferior extremity is provided with a short
spine, a little turned backwards.

The head is rather small, and has no beak. It is
deeply sinuated at its junction with the body, rising
rather erect from that with a projection, and terminating
in a blunt, rounded extremity, nearly filled with the eye,
which is large and areolar. The filaments of the inferior
antennae are not plumose. The sixth segment of the body
is furnished with two projections, and a rather long spur.
Ova about four in number. The colour of the shell is
slightly greenish.

The ephippimn in this species differs considerably from
that of the puleoc. It is more rounded, white in the centre,
with a large round ampulla, containing only one ovum
(t. XII, f. 2). When the animal has the ephippium on, it
possesses a square appearance, and is then the Daphnia
quadrangula of Muller.

In the month of September 1846 I found many spe-
cimens of the male of this species at Highgate and Batter-
sea ; and since then I have again found them at Highgate.

7

08 BRITISH ENTOMOSTUACA.

The antenna consists of along, round body, formed of two
joints (t. XII, f. 1 a) \ the first, the smaller of the two ; the
second, much larger, cylindrical, and furnished with a
short seta on each side. This joint is terminated by a
long, sharp spine, which, at about the half of its length,
appears jointed. The first pair of feet (t. XII, f. 1 b]
are exactly the same as in pulecc. The shape of the shell
differs considerably from that of the female, being more
oval, less rounded on the dorsal edge, and having the
anterior margin straighter.

The head, also, is rather longer, and even more erect
than in the female.

Ilab. — Ponds and ditches in the neighbourhood of
London, Berwick, &c., and commonly met with during
all the summer and autumnal months.

6. DAPHNIA ROTUNDA. Tab. X, figs. 4, 4<2; Tab. IX,
fig. 6, jun.

DAPHNIA ROTUNDA, Straus, Mem. Mus. Hist. Nat,, v, t. 29, f. 27, 28.
M. 'Edwards, Hist. Nat. Crust., iii, 381.
Baird, Trails. Berw. Nat. Club, ii, 1 IV

DAPIINIA RKTIC i J.ATA, Iitiii-il, Ann. Mag. Nat. Hist., i, 257, t. 9, t'. 1 1 .
Du'iiMA <ji \i»i; \\GULA (?), J\<><-/t, Dciitsch. Crust., h. xxxv, t. 19.
DATUM A MUCRONATA (?), Koch, 1. c., h. xxxv, t, 20.
(Young) DATIIMA ANM i.<>s\ (P), Koch, 1. c., h. xxxv, t. 22.

The shell or carapace in this species is nearly quite
round, and the inferior extremity is provided with a short,
blnut spine, projecting backwards.

The head is small, depressed, and notched a little
above its junction with the bod\.

The superior antennae are of moderate size, of a flattened
-hape, square at the tip, and sending off from its upper
edge a short, square branch (t. X, f. 4 a), both branches
being terminated by se\eral short srt;e. The filaments
of the large antenna1 are not plumose. The surface of the
\alves i> densrh retieiiliited, being e«\eivd \\\\\\ a regular

DAPHNIA. 99

network, of small, irregular pentagonal cells. The colour
is generally somewhat red. The sixth segment of the
body is destitute of the spur which is found in the reticu-
lata. The ova are more numerous. The whole animal
is larger, and it possesses a greater density of structure.

Hob. — Ponds and ditches in the neighbourhood of
London, during summer and autumn.

7. DAPHNIA MUCRONATA. Tab. X, figs. 2, 3.

DAPHNE MUCRONATA, Miiller, Zool. Dan. Prod., No. 2404, 1776.
DAPHNIA MUCRONATA, Miiller, Eutomost, 94, t. 13, f. 5, 6.

Desmarest, Cons. gen. Crust., 374.
Latreille, Hist. Nat. Crust., iv, 229.
Bosc, Man. d'Hist. Nat. Crust, ii, 281.
M. Edwards, Hist. Nat. Crust., iii, 382.
Baird, Trans. Berw. Nat. Club, ii, 148.
MONOCULUS MUCRONATUS, Gmelin, Linn. Syst. Nat., edit. 13th, i, 3000,

No. 28.

Manuel, Enc. meth., t. 265, f. 19.
Jurine, Hist. Nat. Mouoc.,137,t.l4,f.l, 2.
MONOCULUS BISPINOSUS, De Geer, Mem. servir Hist. Ins., vii, 463,

t. 28, f. 3-8, 1778.
Falricius, Ent. Syst., ii, 493.
DAPHNIA BISPINOSA, Koch, Deutsch. Crust., h. viii, t. 1.

This species is readily distinguished by the anterior
edge of the shell being quite straight, and terminating
inferiorly by a spinous point of considerable length.

The head is of a triangular shape, and the eye is large.

Superior antennae short.

Filaments of inferior antennae not plumose.

The back is impressed with a deep indentation at the
root of the head ; and the anterior margin is marked with
brownish coloured bands, and densely ciliated.

The colour of the whole animal is of a dark gray.

The form of the head varies in this species, being
sometimes rounded, and at others terminated by a sharp,
somewhat curved point directed upwards.

100 BRITISH ENTOMOSTRACA.

The figure which Miiller gives of this species repre-
sents the head rounded ; that of De Geer, with a sharp
point.

Miiller says, " variat fronte cornuta, cornu perpendicu-
lariter erecto."

Jurine figures it with the rounded head, and finds fault
with De Geer's figure, which, he says, " does not appear
to me to be correct, since it presents the nasal prolonga-
tion of the shell curved forwards, in place of it being
downwards. That of Miiller is better in this respect,
although it is not perfect."

In the month of August 1841 I found, in the neigh-
bourhood of Isleworth, this species very frequently with
the sharp-pointed head; and I observed, that all those
which came under my notice having the ephippium upon
them, possessed the rounded head. Among them, how-
ever, I found several with this form that had young in
the ovary, and no ephippium. As in the same pond there
occurred many individuals, both with the sharp and the
rounded head, and as at the same time they did not vary
in any other respect, I can only consider them as varieties.

Var. a. Acute rostrata. Head terminating in a sharp
point directed upwards (t. X, f. 3).

Var. /3. Obtuse rostrata. Head rounded superiorly
(t. X, f. 2).

Hob.- — Ponds about Isleworth, &c. ; from June to
October.

Genus 2 — MOINA.

Head rounded and obtuse. Superior antennae of con-
siderable length, one-jointed, arising from the front of the
head, near the centre. Inferior antennae very large, and
at the base.

MOINA. 101

1. MOINA RECTIROSTRIS. Tab. XI, figs. 1, 2.

DAPHNE RECTIROSTRIS, Midler, Zool. Dan. Prod., 199, No. 2402, 1776.
DAPIINIA RECTIROSTRIS, Mailer, Entoraost., t. 12, f. 1-2.

Latreille, Hist. Nat. Crust., iv, 228.
Bosc, Mem. d'Hist. Nat. Crust., ii, 281.
Demarest, Cons. gen. sur les Crust., 373.
Scfirank, Eaun. Boic., iiii, 266.

MONOCULUS RECTIROSTRIS, Gmelin, Linn. Syst. Nat., 3000, No. 26.

Fabricius, Eutomol. Syst., ii, 493, No. 15.
Manuel, Enc. meth., 723, No. 19, t. 2G5,

f. 10-12.

Jurine, Hist. Monoc., t. 13, f. 3, 4.

PASITHEA RECTIROSTRIS, Koch, Deutscb. Crust., h. xxxv, t. 24.*
PASITHEA GIBBA (?), Koch, 1. c., h. xxxvi, t. 16.
DAPHNIA MACROCOPUS (?), Straus, Mem.Mus. Hist. Nat.,v,t. 29,f.30.

The shell or carapace of this species is oval, transparent,
rounded at the back, and ciliated along the anterior margin.

The head is erect, of considerable size, the inferior
extremity rounded, and furnished posteriorly with a very
slight spine, or tail.

The antennules are of considerable size, of one joint,
flattened, and furnished at the extremity with three or
four short setae. The inferior antennae are very large,
the basal joint stout and fleshy, the branches long and
powerful, and the setae all finely plumose.

The abdomen is emarginated at about half its length,
and terminates in two stout, curved spines.

The male is smaller than the female, and is more slender
in form. The superior antennae are very long (t. XI, f. 1 «),
and apparently consist of two long, flat joints, the terminal
one having at the extremity a series of very small hooks.
When very young, the male has a long spine at the in-
ferior extremity of the carapace, and the head is much
more rounded. As moulting takes place, however, he
loses the spine, and the head becomes more elongated,

Hob. — Pond upon Blackheath, October 1849.

* The genus Pasithea, having been used in zoology twice previously, cannot
be retained.

102 BRITISH ENTOMOSTRACA.

2. MOINA BRACHIATA. Tab. IX, figs. 1, 2.

MONOCULUS BKACHIATUS, Jurine, Hist. Monoc., 131, t. 12, f. 3, 4.
DAPHNIA BRACHIATA, Desmarest, Cons. gen. Crust., 373.

M. Edwards, Hist. Nat. Crust., iii, 383.

Baird, Zoologist, i, 196, fig. at p. 193; Trans.
Berw. Nat. Club, ii, 148.

The length of this little creature is about half a line.
The shell or covering is of an olive colour, transparent,
showing the stomach and intestine very plainly. It bulges
out very much posteriorly, giving the animal a very jolly
appearance, and is ciliated anteriorly.

The superior antennae are large and long, projecting
straight out from the beak, somewhat cylindrical in shape,
giving off from their upper margin one or two small
spines, and terminated by several short setae. The main
stalk, or basilar joint of the inferior antennae, is very
large, and fleshy-looking ; the under edge, for about
half its length from the base, being crenated, and having
two short setae springing from one of the crenations, or
small lobes, at about the middle of its length ; the upper
edge also is crenated. The articulations of the branches are
somewhat serrated on the edges, and the long setae with
which they are furnished are all finely plumose, and jointed
about the middle of their length.

The abdomen has at its extremity eight short spines
on the inner edge, and two long, stout claws. The two
seta? on the seventh joint of body are long, plumose, and
jointed.

This species is not so active as some others of this
genus, owing perhaps partly to the form. It has a great
many ova.

Halt. — I first found this species in a stagnant pool in
old St. Panrras road, London, nearly opposite old St.
Pancras Church, in the summer of 1844. Since then,
the pool in which it occurred has been built over. Pond
on Blackheath, June 1848.

MACROTHRIX. 103

Genus 3 — MACROTHRIX.*

MACROTHRIX, Baird, Ann. Mag. Nat. Hist., xi, 87, 1843, and xvii, 412 ;

Trans. Berw. Nat. Club, ii, 149.
DAPHNIA, M. Edwards, Hist. Nat. Crust,, iii, 384.

Nulhr (?), Eutomost.

LYNCEUS, Desmarest, Cons. gen. et part. Crust., 370.
MONOCITLUS, Jurine, Hist. Monoc. Geneve.
ACANTHOCERCUS, Schodler, Erichs. Archiv, 1846.

Character. — Superior antennae flat, one-jointed, pen-
dulous from the beak. Filament from extremity of first
joint of anterior branch of inferior antennae much longer
than any of the others. Eye accompanied with a black
spot.

1. MACROTHRIX LATICORNIS. Tab. XV, fig. 2.

DAPHNIA CURVIROSTRIS (?), Mutter, Entomost., t. 13, f. 1, 2.
MONOCULUS LATICORNIS, Jurine, Hist. Monoc., t. 15, f. G.
LYNCEUS LATICORNIS, Desmarest, Cons. gen. part. Crust., 376.
MACROTHRIX LATICORNIS, Baird, Ann. Mag. Nat. Hist., xi, 87, t. 2,

f. 9, 10; Trans. Berw. Nat. Club,ii, 149.
ACANTHOCERCUS CURVIROSTRIS (?), Schodler, Erichs. Archiv, 1846.

The shell or carapace is of an oval shape, transparent,
colourless, smooth, strongly ciliated on anterior margin.

The inferior antennae or rami are strong and large
(t. XV, f. 2 a). The posterior branch has four setae ; three
from the extremity of the last articulation, and one from the
extremity of the second. The anterior branch has five seta?,
four disposed as in the posterior branch, and one very long,
from the extremity of first articulation. Superior an-
tennae pendulous from the extremity of the beak, rather
broad, becoming narrower at their base, and furnished
with three short setae at their extremities.

Eye large, distinctly areolar, and having an accom-
panying black spot near the root of the superior antennae.

* MaKpoj, long ; and QpiK, a hair.

104 BRITISH ENTOMOSTRACA.

Intestine straight, not convoluted ; but more distinctly
curved at its upper extremity than in the other Daphniadae.

Hob. — Pond at Southall, Middlesex, June 1841;
Sept. 1849. Pond at Highgate, July 1842; Sept. 1849.
Belfast, May 1849, W. Thompson, Esq.

2. MACROTHRIX ROSEUS.

MONOCULUS ROSEUS, Jurine, Hist. Monoc., t. 15, f. 4, 5.
LYNCEUS ROSEUS, Desmarest, Cons. gen. et part., 376, t. 54, f. 8-9.
DAPHNIA KOSEA, M. Edwards, Hist. Nat. Crust., iii, 384, No. 14.

Yarrell, British Fishes, ii, 93, vignette.
MACROTHRIX ROSETJS, Bairfl, Trans. Benv. Nat. Club, ii, 149.

This species differs very little from the preceding. The
shell or carapace is smooth, and very transparent ; an-
teriorly it is ciliated. The superior antennae are longer
and narrower than in laticornis, and are furnished with
three very short setae at their extremity. The eye is con-
siderably smaller, and has no areola round it. The colour
of the whole animal is of a rosy hue. Eggs two.

It swims horizontally ; and when it bounds through
the water, the motions of its arms are soft and graceful.
It forms great part of the food of the Vendace (Corre-
ffonus Willuglibii}.

M. Edwards considers this and the preceding to be
the same species.

Hab. — Lochmaben Loch, Dumfriesshire, Sir W.
Jardine, Bart., W. Yarrell, Esq.

As I have not seen this species, I have not figured it.
It may turn out to be only a variety of the preceding, if
not exactly the same.

BOSMINA.

Genus 4 — BOSMINA.*

DAPHNIA, H. Edwards, Desmarest, Baird.
MONOCULUS, J urine.
LYNCEUS, Muller, Latreille.

BOSMINA, Baird, Trans. Berw. Nat. Club, 1845 ; Ann. Mag. Nat.
Hist.,xi, 412.

Character. — Superior antennae long, curved, cylindrical,
consisting of many small articulations, and projecting
from the extremity of the beak. Inferior antennae small
compared with preceding genera.

1. BOSMINA LONGIROSTRIS. Tab, XV, fig. 3.

LYNCEUS LONGIROSTRIS, Muller, Zool. Dan. Prod., No. 2394 ; Eiito-

most., 76, t. 10, f. 7,8.
Latreille, Hist. Nat. Crust., iv, 206.
Fabricius, Ent. Syst., ii, 499.

MONOCULUS CORNUTUS, Jurine, Hist. Nat. Monoc., 142, 1. 14, f. 8-10.
DAPHNIA CORNUTA, Desmarest, Cons. gen. Crust., 375.

Baird, Ann. Mag. Nat. Hist., ii, 257, t. 9, f. 15.
M. Edwards,~Hist. Nat. Crust., iii, 382.
BOSMINA CORNUTA, Baird, Trans. Berw. Nat. Club, ii, 149.
BOSMINA LONGIROSTRIS, Baird, Ann. Mag. Nat. Hist., xvii, 412.
EuNiCAf LONGIROSTRIS, Koch, Deutscb. Crust., b. xxxv, t. 23.

This animal is very small. The shell or carapace is
rounded on the posterior margin, bulging out anteriorly,
and terminating at the inferior angle in a sharp point or
spine, which projects straight downwards. The superior
antennae consist of twenty articulations ; the first seven
are short and close to each other ; at the beventh two or
three setae spring, projecting forwards and upwards;
then follow thirteen articulations, each one longer than
the preceding. It requires a strong magnifying power

* " Bosmina," a daughter of Fingal.

f As tbe terms EUNICE and EUNICAE bave been already used in zoology,
and as tbis genus is not characterised by Koch, I have preferred retaining
the name I applied to it in 1845.

100 BRITISH ENTOMOSTRACA.

to make out this articulated structure distinctly. Like
the antennules of the Daphniadae and Lynceida?, they
appear to be almost destitute of motion, and thus when
seen close to each other, they certainly bear a close re-
semblance to a prolongation of the beak. The inferior
antenna, though strong bodies, are much shorter than in
most of the Daphniadae. The anterior branch has four
articulations ; the posterior only three. They are furnished
with long filaments, which are not plumose. The ova are
few in number.

The motion of this curious little creature through the
water is caused by numerous and very rapid strokes of
its inferior antennae or rami, being in that respect very
similar to the Lyncei. The males I have never met
with.

Hab. — New River, London ; Highgate ponds. I have
every summer for several years past met with it abundantly
in the common drinking-Avater of London supplied from
these two sources.

SIDINA.
Genus 1 — SID A.

SIDA, Straws, Mem. Mus. Hist. Nat., v ; M. I-','/ wards, Bnird, Dftna.
DAPHNIA, J//-/A /-, /,,//,>•/'//<", Bosr, A
MONOCULUS, De Geer, «////•///<•, &c.

Character. — One branch of Inferior antennae \\ith three,
the other with two articulations, lavL-v and powerful.
Superior antennae of moderate size.

SIDA.

107

1. SIDA CRYSTALLINA. Tab. XII, figs. 3,4; Tab. XIII,
fig. 1 a-li.

DAPHNE CRYSTALLINA, Midler, Zool. Dan. Prod., No. 2405, 1776.
DAPHNIA CRYSTALLINA, Milller, Entornost., 96, 1. 14, f. 1-4.

Latreille, Hist. Nat. Crust., iv, 230.
Bosc, Mem. d'Hist. Nat. Crust., ii, 281.
SIDA CRYSTALLINA, Straus, Mem.Mus. Hist. Nat., v.

M. -Edwards, Hist. Nat. Crust., iii, 385.
MONOCULUS CRYSTALLINUS, Gmelin, Liim. Syst. Nat. edit. 13th, i,

3000, No. 29.
Manuel, Enc. meth., vii, 724, t. 265,

f. 15-18.

Fabncius, Ent. Syst., ii, 493.

MONOCULUS ELONGATUS, De Geer, Mem. servir Hist. Ins., vii, 470,

t. 29, f. 1-4, 1778.

Carapace or shell elongate-ovate, very transparent,
truncate at inferior extremity. Head (t. XII, f. 3 A) large,
with a projecting plate at the posterior part (f. 3 A, q).
Eye large and round (t. XII, f. 3 b, 3 A, c}. Body within
the carapace very narrow, nearly straight.

Abdomen has at the bend a projecting knob, with two
long seta? proceeding from it, and terminates in two long,
stout claws, each of which has three spines on its inner
edge (t. XIII, f. Ji). Between the knob and the termina-
ting claws the inferior edge is beset with two rows of about
twenty short spines.

The superior antennae (t. XIII, f. a) are rather large and
long, and armed at extremity with four short spines. They
spring from a knob or eminence projecting a little out
from the edge of the shell. The inferior antennae or rami
are large (f. b}. The basal joint is very stout and rounded,
more than a third the length of the whole organ, and
furnished with three short spines on anterior extremity.
The two branches are rather short, compared with the
size of the basal joint and the size of the animal. The
external branch is divided into three articulations. The
first, or lowest, is very short, and has a small spine at
the outer angle ; the two others are nearly of equal length.

108 HUTTISII ENTOMOSTRACA.

The second has three plumose setae springing from its
inner edge, each arising from a small projection, and
furnished with a joint about the middle of their length ;
and one short simple spine from outer angle at the an-
terior extremity. The third has seven similar seta:, four
on the inner edge, and three at the extremity, besides
one short simple spine at the outer angle. The inner
branch has only two joints, the first much the longer of
the two, and having at its extremity or inner edge one
short simple spine, and one long seta, the second or
terminal very short, and having four long plumose seta?
from its upper edge.

The mandible (t. XIII, f. c; t. XII, f. 3 A,/) is similar
to that of Daplnria Schwfferi, and has a row of cutting teeth
on its edge. The labrum (t. XII, f. 3 A,y) is like that of
Daphnia, and is provided with a strong muscle. The
intestinal canal is large. The oesophagus is in form of a
narrow, slightly-curved canal, which terminates a little
below the eye in a large cul-de-sac, the commencement
of the stomach (t. XII, f. 3 A, c). There docs not appear
to be any organ corresponding to what has been described
in Daphnia as the c&cvm. The feet are six pairs in
number, and differ from those in the Daphnina, and also
from each other. The first pair (t. XIII, f. d] consists of \\
main stalk of two articulations, one of which has four
seta?, the other seven. From the inner edge springs a
large branchial plate provided with about thirty filaments,
and from its upper part a smaller plate arises furnished
witli nine or ten short filaments, and one longer and
plumose. The four succeeding pairs are more like each
other, but diller somewhat- from (lie first pair. They
each it. XIII, Le,f) possess a small triangular plate fixed
upon the edge of the main stalk, and taking the place of
the seta? which arc found in the preceding. The smaller
branchial plate is shorter, broader, and square-shaped,
and the branchial filaments of both plates are shorter.
The sixth pair (t. Mil, f. //) differs from all the others.
Kadi foot consists of (hive articulations, each furnished

DAPHNELLA. 109

with several strong setae, and the whole organ presents a
curved appearance. In full-grown females (t. XII, f. 3)
the ovary contains upwards of twenty young, and the ani-
mals then present a different appearance from those which
have no ova (t. XIII, f. 1). The young resemble the
parent from their birth. Twenty-four hours after being
born they appear as represented in t. XII, f. 4.

The motion of the Sida through the water is a sort of
rapid running movement. They are generally inactive,
and adhere in a peculiar manner by the back of their head
to the side of the vessel in which they are contained,
remaining there for hours. They adhere most probably
in the same way to the weeds in the water where they
are found, as it is by skimming the stems of the weeds
that they are detached and caught. They do not appear
to be numerous in the localities in which I have found
them, and indeed are of rare occurrence.

Hab, — Back fishpond at Overstone Park, Northamp-
tonshire, July and August, 1849 ; ditch near Richmond,
opposite Isleworth, August, 1849 ; found near Dublin,
by Professor Allman, VV. Thompson, Esq., July 1848.

Genus 2 — DAPHNELLA.

Inferior antennae very large ; both branches consisting
each of only two articulations.

1. DAPHNELLA WINGII. Tab. XIV, figs. 1-4.

Carapace elongated, rounded at the back, slightly curved
at inferior extremity, and having a small mucronation,
somewhat truncated in front, and of a beautiful, clear,
crystalline transparency.

The head is long and narrow.

Eye (t. XIV, f. 4 c] large, round, composed of upwards
of forty crystallines, and nearly filling the upper part of
the head.

110 BRITISH ENTOMOSTUACA.

Superior antennae (f. 4 It) long and rather slender,
and provided with two setae at their extremity, of con-
siderable length. Inferior antennae or raini very large
and powerful ; the basal joint is particularly so, and fleshy-
looking ; the two branches are also large, and each divided
into two articulations. Both articulations of posterior
branch are nearly of equal size, the inferior having three
and the upper eight long filaments springing from their
inner edge. These filaments are not plumose, but are
jointed at the middle of their length. The joints of the
anterior branch are of unequal length, the first being long,
and furnished with only one filament ; the second being
very short, and sending off three long setae from its upper
edge.

The mandible (f. 4/), labrum (f. 4 g), oesophagus
(f. 4 0), and stomach (f. 4 a) are almost exactly the same
as in Sida.

The abdomen consists of a broad plate, with large knob
and two long setas, and has two rows of short spines on
its edge, as described in preceding genus.

The feet also resemble those of Sida, and are six pairs
in number.

The male (t. XIV, f. 2) is smaller than the female, and
is beautifully transparent. The antennules (f. 2 a] are
long, with a tooth on the upper edge, about the middle
of their length, and three long setae at their extremity.
The abdominal plate (f. 2 fj) appears to have a supple-
mental plate, which covers it, and which is flat, broad,
and curved at the lower extremity.

•

The female has verj few young, only two or three.

The motion of this beautiful little animal is by sudden
bounds, darting forwards, by means of its large rami, for
i great distance at each bound.

Unit. — Pond on the edge of the Colnc, between Twick-
enham and \Yhitton, Middlesex, July 1s II ; ditch near
Richmond, opposite [sleworth, July ISM, August lvh>.

POLYPHEMUS. Ill

Family 2— POLYPHEMID^l.

.s, Baird, Trans. Berw. Nat. Club, ii, 149, 1845.
Dana, Proc. Amer. Acad. Arts and Sc., 1849.

Character. — Four pairs of feet, not contained within
the shell. Eye very large. Inferior antennae two-branched,
one branch having four, the other three articulations.
Lower part of shell forming a large vacant space, for con-
taining the ova and young.

This family contains two British genera, Polyphemus
and Evadne.

Genus 1 — POLYPHEMUS.

POLYPHEMUS, Midler, Cuvier, Latreille, Straus, Edwards, &c.
MONOCULUS, Linnaeus, Geoffrey, De Geer, Faliricms, J-tirine,
CEPHALOCULUS, Lamarck, Bosc.

Character. — Head distinct from body. Abdomen long,
projecting externally from the shell.

I. POLYPHEMUS PEDICULUS. Tab. XVII, fig. 1.

MONOCULUS PEDICULUS, Linnceus, Faun. Suec., No. 2048, 1746; Syst.

Nat., edit. 10th, i, 635, No. 5 ; edit.
12th, i, 1058, No. 5.
Gmelin, Linn. Syst. Nat,, edit. 13th, i, 3001,

No. 5.

Fabricms, Ent. Syst., ii, 502; Sp. Ins., i, 374,
No. 7 ; Mantissa Ins., i, 240, No. 7.
Sulzer, Insecten, t. 30, f. 8 a.
Manuel, Eucyclop. meth., vii, 718, t. 263, f. 1.

MONOCULUS PEDICULUS RAMOSUS, De Geer, Mem. pour serv. a 1'Hist.

Ins., vii, 467, t. 28, f. 9-13, 1778.
POLYPHEMUS OCULUS, Midler, Zool. Dan. Prod., No. 2417, 1776 ;

Entomost., t. 20, f. 1-5.
Cuvier, Tab. element., 456.
Lati-eille, Hist. Nat. Crust., iv, 287 ; Genera
Crust, et Ins., ii, 20.
?, Ediu. Encyc., art. Crustaceology.

112 BRITISH ENTOMOSTRACA.

POLYPHEMUS STAGNORUM, Leach, Diet. Sc. Nat., xiv, 540.

Latreille, Cuv. Reg. An., iv, 165.
Desmarest, Cons. gen. Crust., 365, t. 54,

f. 1.
POLYPHEMUS PEDICULUS, Straus, Me"m. Mus. d'Hist. Nat., v.

M. Edwards, Hist. Nat. Crust., iii, 389.

MONOCULUS POLYPHEMUS, Jurine, Hist. Nat. Monoc., 143, 1. 15, f. 1-3.
CEPHALOCULUS STAGNORUM, Lamarck, Hist. An. s. Vert., v, 131.

Bosc, Man. d'Hist. Nat. Crust., ii, 247.

LE MONOCLE 1 QUEUE RETROUSSEE, Geoffrey, Ins. Par., ii, 656, No. 2.
MONOCULUS OCULUS, Gmelin, Linn. Syst. Nat., edit. 13th, i, 2996,

No. 10.
SCALICERUS PEDICULUS, Koch, Deutsch. Crust., h. xxxvii, t. 2.

The body is oval-shaped, separated from the head by a
deep indentation.

The upper part of the head is almost entirely occupied
with the eye, which is provided with its rotatory muscles,
as in the Daphniadae, and is beset, all round the upper and
outer edges, with numerous lucid areolae, about twenty in
number. The lower part is quite transparent, the black
mass filling only about three fourths of the whole.

The mandibles are almost exactly the same as in the
Daphnia.

The inferior antennae or rami (t. XVII, f. 1 ci] are large,
and divided each into two branches. The anterior branch
has three articulations : the first the largest ; the second
is the shortest ; and the third is the longest and the most
slender. The first joint has one seta, the second one also,
and the third has two from the side, at equal distances from
each other, and three from the apex. The posterior branch
has four articulations, one very short and three longer. The
second joint has one seta at its extremity ; the third has
one springing from the middle of the articulation, and one
from the extremity. The last joint has one seta on its
edge, and three at its extremity. The setae are jointed at
about half the length.

The superior antennae are small, arising from the edge
of the head below the eye ; they are sharp-pointed, and
terminate in two or three fine seta-, directed upwards.

POLYPHEMUS.

113

The intestine is curved, but not convoluted.

The body of the animal is only partially inclosed
within the shell. It is fleshy, and after descending in it
about two thirds of its length, turns upon itself from be-
hind forwards, and folds itself suddenly backwards, to
form a long and slender tail, which projects from the shell,
and protrudes externally, extending fully the length of the
carapace. It is serrated on the outer edge, and terminates
in two long setae. This organ differs very much from that
of the Daphnia3, and, as J urine says, seems to serve as a
rudder.

The heart is situated at the same part of the body as
in the Daphnise, near the junction of the head and body.

The lower part of the shell seems to be the matrix or
receptacle for containing the ova, which are generally
about six in number.

The legs (t. XVII, f. 1 b] are four pairs, always pro-
jecting from the shell externally. They are four-jointed,
and provided at the extremity of the last joint with
several plumose setae. The fourth pair are shorter than
the others, and want these setae. These organs resemble
more the legs of the Ci/dojrid<% than the other animals of
this family, and are, in accordance with their structure,
used by the Polyphemus for swimming. It always swims
upon its back, and generally horizontally, with quick re-
peated motions of the antennae and legs, which carry it
rapidly through the water.

Like the Daphniae, the Polyphemus has, at particular
seasons, the ephippiimi, or saddle, which serves exactly
the same purpose as in them. The number of young is
not so great as in the Daphnias, seldom reaching, at the
most, to the number of ten, but more frequently about six.
It is very difficult to make accurate observations on the
manners and habits of living and propagating their species
in this genus, as the little animals are very difficult to be
kept in captivity. In the young, even when in the matrix,
it is particularly observable, that the eye very soon makes

8

114 BRITISH ENTOMOSTRACA.

its appearance, an organ so large in the adult, that Miiller
says " its head is all eye."*

The males have never yet been noticed by any observer.

Hob. — Ditch near Richmond, on the banks of the
Thames, nearly opposite Tsleworth, July. It seems to be
very limited in its range of habitat, for though this ditch
is frequently filled by the tide from the river, and is fully
a mile in length, I have only found it in one spot, not
much above twenty yards in extent.

Genus 2 — EVADNE.

EVADNE, Loven, Zoologisk. Bidrag., p. 1.

M. Edwards, Hist. Nat. Crust., iii, 390.
Goodsir, Edin. Phil. Jouru., xxxiii, 366.

Character. — Head not distinct from the body. Abdo-
men short, scarcely projecting from the shell.

1. EVADNE NORDMANNI. Tab. XVII, fig. 2.

EVADNE NORDMANNI, Loven, Zoologisk. Bidrag., t. ], 2 ; Do., Kougl.

Vctcuskaps. Acad. Hadliugar., t. 1, f. 1-8.
H. iV«wd*,Hist. Nat. Crust., iii, 390, t. 36, f. 7.
Goodsir, Edin. Phil. Journ., xxxiii, t. 6, f. 15, 16.

The whole animal is almost colourless, except the poste-
rior part of the eye, which is black. The anterior portion
is much the larger, and deeply ribbed longitudinally.

Antennae composed of two branches. A number of
long setae spring from the extremity of each.

The legs (t. XVII, f. 2 a) arc four pairs, and arise
almost immediately below the eye. They are each com-
posed of four articulations, which arc all furnished with
several strong sctaj. A powerful muscle extends from the
legs, and passing upwards immediately behind the eye, is
attached to the dorsal portion of the shell. The whole

* "Caput totum oculus."— Entomosl.. 1 1v

LYNCEID.E. 115

of the internal cavity of the shell immediately behind
the muscle is apparently empty, except at the season of
spawning, when it is full of ova or young.

The posterior part of the body is produced in the
middle into a strong, pointed spine.

The feet are much thicker than those of the Daphniae,
and the construction of these organs appears to establish
a passage from the Cladocera to the Copepoda.

The habits of this animal are extremely active, and very
similar to those of the Daphniae. They form part of the
food of the herring.

Hab.— Firth of Forth; H. Goodsir.

Family 3— LYNCEIDJ5.

LYNCEUS, Midler, Latreille, Manuel, 8fc.
DAPHNIDES (in part), Straus.
DAPHNIDIENS (in part), M. Edwards.

(in part), Baird, Ann. and Mag. Nat. Hist., ii.
, Baird, Trans. Berw. Nat. Club, ii, 150, 1845.

Character. — Two pairs of antennae ; superior, very
short ; inferior, of moderate size, branched ; each branch
divided into three articulations. Feet five pairs. Eye
single, but accompanied with a black spot in front of it.
Intestine convoluted, having one complete turn and a
half. Abdominal portion of the body jointed.

Bibliographical History. — Miiller established the genus
Lynceus in his ' Zool. Dan. Prod.,' in 1776, and so named
it, from its having, according to his idea, two eyes.
Previous to this time no author had ever taken notice of
any species belonging to it. In 1781 he confirmed the
genus, in his work on the ' Entomostraca ;' described nine
species, and gave a few particulars regarding them.

About the same time Schrank and Eichhorn simul-
taneously mention an insect which evidently belongs to
this genus, and which may probably be only one and the

116 BRITISH ENTOMOSTRACA.

same species. The first of these two authors, in his
'Enum. Insect. Austria)/ 1781, p. 530, No. 1119, de-
scribes it briefly as " Monoc. infusorius, testa bivalvi,
rostratus, oculis duobus in rostro sitis," and says it is
very abundant in stagnant waters, and is perhaps the
smallest of its congeners. Eichhorn gives a figure of his
insect, says it is distinguished from that " Wasserfloh"
described by Schceffer (Daphnia), inasmuch as it has
a pointed beak which lies close upon the mouth ; that
it differs from it in its motion through the water, not by
bounds, but swimming like other insects, and that it is
exceedingly common.* These authors give little satis-
factory information j however, respecting the gen as ; and
Miiller's characters are very indifferent, as will be shown
more clearly hereafter. His species, without any original
matter, are given by Gmelin, in his ' Syst. Natur. Linn./
1778 ; Manuel, in the ' Encyc. meth./ 1792 ; Eabricius,
in his ' Entom. Syst./ 1793 ; Latreille, in his ' Hist. gen.
et part, des Crust, et Ins.' 1802 ; and Lamarck, in his
'Hist. Nat. des Anim. s. Verteb.' 1818: but no new
species are added.

Leach is the only British naturalist that has particularly
noticed the genus Lynceus. In the Supplement to the
'Encyc. Britann./ art. Annulosa, 1816, and in the
'Diet, des Scien. Nat.' xiv, 541, 1819, he appears to
have been sensible that it was ill formed, and splits it
into two ; but with the exception of this, we have; nothing
new written upon the genus until Jnrine published his
' Hist, des Monoc./ in 1820. In this work he has given
us a few particulars with regard to the question of their
having two eyes, the mode of reproduction, &c. He
notices several of Mailer's species, describes three or four
new ones, and hints at the necessity of reforming the
genus altogether. These additional species are given,
along with those of Miiller, by Desmarest, in his ' Consul,
gen. sur Irs Crust./ 1825; but we have no new inlor-

- Beyt. /in- N:itnrg., p. 37, t 3, f. n : US1.

LYNCEID;E. 117

ination till Milne Edwards published his work on the
Crustacea in 1840.* In this work the author shows
the necessity for breaking down this heterogeneous genus,
and reforming it ; but he does not make the attempt
himself, nor do I know of any attempt having been made
before I published my paper on the Lynceus, in the
' Annals and Magazine of Natural History/

Anatomy and Physiology^ Sfc. — In general formation
the animals of this family are very much like the
Daphniadae; the most remarkable points of difference
being the shape of the head and beak, and a small black
spot a little distance from the eye, much smaller than it,
which is considered by Miiller as a second organ of vision,
and from which he has given the name to the genus. f
The shell or covering which incloses the body does not
consist of two distinct and separate valves, but is open
only on the anterior margin, and for a portion of the
posterior extremity. The part which we may call the
head is harder than the other portion of the shell, and is
prolonged in most of the species into a sharp and very
distinct beak. Belonging to it we find, besides the beak,
the eye with its accompanying black spot, the superior
antenna, the inferior, or rami, the brain, mouth, and
part of the digestive canal.

The eye (t. XV, f. 1 /), as in the Daphniadse, is a
spherical body contained in a somewhat funnel-shaped
sheath of muscles, having a semirotatory motion, and
consisting of a series of crystalline bodies ; which, in the
Eurycercus lameUatus, are about twenty in number.

The black spot, which Miiller considers as a second eye,
is situate before, and at a little distance from, the real
eye, generally near the end of the beak, almost at the
extremity of the body of the animal, and near the root
of the antennae. It is much smaller than the eye, has no

* Hist. Nat. des Crust., vol. iii.

f "Nomeu Lyncei in Zool, Dan. prod, ex punctis binis ocellaribus, qua;,
organa visas absque d'ubio sunt, indixi." — Eutomost., p. 67.

118 BRITISH ENTOMOSTRACA.

communication with it, and is immoveable. It is not
composed of crystallines, and its situation is not exactly
the same in all the species.

Jurine says he has only examined it in small indi-
viduals, and that in consequence he has not been able to
discover its utility. He does not appear to have met
with the larger individuals of this family, such as the
Eurycercus lamellatus, in which I have examined this
spot, but without being able to ascertain any use to
which it is applied. I quite agree with him, however, in
considering it to be not an organ of vision.

Straus considers the upper larger spot the only one
deserving the name of eye, and this small black spot
to be similar to that existing in the Daphniadae ad-
jacent to the brain, the relative situation of which is
also nearly the same as this black spot in the Lynceidae.
We find it in the young before birth exactly as in the
adult.

The antennae are four in number, two superior and two
inferior, and are situate as in the Daphniadae. The su-
perior antennae (t. XV, f. 1 a) consist each of a solid body,
of a somewhat conical shape, and slightly curved, which
terminates in six short spines, each of which again gives
out a fine seta or bristle. They are not possessed of much
motion. The inferior antennae, or rami as they are some-
times called (t. XV, f. 1 6), are situate on each side of the
base of the head, rather lower than in the Daphniadae,
and consist, as in them, of a single joint at the base, which
divides into two branches, each having three joints ; they
are much shorter in all the species than in the Daphniadae.
In the AV/v/rv/Yv/.v /Wr//W//.v (he anterior branch sends oft'

t/

from the last joint three Ion*; filaments or bristles, and a
short one, and one from the extremity of the second and
iirst joints ; while the posterior branch sends off only
three long ones and a short one from the last joint. The
long seta^ are each furnished with a joint near the centre,
as in Dii/ili/iiu /Wr/ •, and, as in it, are beautifully plumose,
while the short set;e are neither jointed nor plumose.

LYNCEID.E. 119

The use of these organs is the same as in the Daphniadae,
being chiefly organs of locomotion.

The brain is apparently the same in situation and in
shape as in the Daphniadas. The mouth also is nearly of
the same construction.

The mandible (t. XV, f. 1 c) is a strong organ, articula-
ting superiorly with the body by a sharp and pointed
extremity, whilst the inferior extremity is free and unat-
tached, curved a little inwards, and rounded somewhat at
the tip, which is furnished with several strong teeth.

The labrurn (t XV, f. 1 d] consists of a large, strong
plate, articulating wiih the body by the narrow end, to
which are attached the muscles which move it. About the
centre of its length it takes a sudden curve, and descends
in the form of a broad plate, which is slightly lunated at
the extremity, the edges terminating in sharp points.
To the lower edge of its superior extremity is attached a
flat, rather square plate, which moves simultaneously with
the other part, and to which it seems firmly fixed. These
organs may be seen almost constantly in motion when the
animal is stationary, the motion of the mandibles being
pretty quick and oscillatory, whilst that of the labrum is
slow, upwards and downwards.

The jaws consist of a flat body, armed at the extremity
with several stout spines (t. XV, f. 1 </:*).

Part of the digestive canal may be seen also in the upper
part of the animal, commencing, as in the Daphniadae,
immediately behind the mouth, in the form of an
oesophagus, and terminating in the stomach, which is
situate in the lower portion of the shell.

The stomach (t. XVI, f . 1 b} differs somewhat from that
organ as seen in the Daplmiaclae, being curved or twisted
into one or two complete convolutions near the centre.

The body of the animal is not jointed, as in the Daph-
niada?, and is quite free and unattached within the valves
of the shell, except at the superior portion, where we see
it attached to the posterior edge of the shell by about
three rather broad muscles. It terminates superiorly in

120 BRITISH ENTOMOSTRACA.

a point near the root of the antennae, and almost upon the
extremity of this point is situate the black spot in front of
the eye. A short distance from this the body has an in-
dentation, in which, or rather on its edge, is situate the
eye, already described. It then takes a round turn, the
edge of which is more or less crenated, and from it the
muscles attaching the body to the shell arise. It now
turns inwards for a short distance, and then bulges out-
wards again towards the posterior edge, terminating by a
joint in the abdomen.* The space left where the body
turns inwards, between it and the shell, is the matrix,
or place where the animal deposits its ova, and where the
young remain till ready to be extruded ; and immediately
above this is situate the heart.

The abdomen (t. XV, f. l/£) in all the species I have
examined is connected to the body by an articulated joint,
differing in this very particularly from the Daplmiadag.
At this joint we see two setae arise, which in some species,
as in the Euryccrcus lamellatus, are beautifully plumose,
and of considerable length. The abdomen is then pro-
jected upwards, being always within the shell when the
animal is at rest. It terminates in two or more hooks,
the use of which seems to be to assist in cleaning the in-
terior of the shell, as the abdomen is flexible, and can be
extended at pleasure to a considerable extent beyond the
carapace. In one or two species it is remarkably long, as
in the Camptocercus n/(icroi/r/>x, and is extremely flexible,
the motion of this organ being evidently of great use to
the animal in assisting and regulating its movements. A
little beyond this joint is placed the anus, or termination
of the alimentary canal.

The feet arc five pairs in number (t. XV, f. 1 <"-/) ; the
first pair arc the largest, and consist each of a fleshy sort of
body, bent a little, strongly ciliated on its upper edge, and
furnished ;il its extremity with five long and strong seta',
\\hich in general project a little beyond the edge of the

' lir body, ;is a!in\e described, j.., particularly \\vll seen in the

LYNCEID/E. 121

valves. The other feet, from their extreme delicacy of
structure and transparency, are difficult to be made out ;
but they closely resemble those of the Daphniadse, con-
sisting of branchial plates and finely plumose setse, and
have the same functions and uses.

These insects are found in stagnant waters and slow-
running streams, amongst the Lemnae and Con fervae which
collect in those situations. The males have not been met
with or described, though two, three, and even four may
often be seen fixed to each other, and swimming about in
that state.* Several species are very abundant through-
out the spring, summer, and autumn, and may be met
with in almost every pond and ditch. They are not, indi-
vidually, however, so prolific as the Daphnise, as they pro-
duce only a few eggs at a time, generally two or three, with
the exception of \k&Eur ycercus laiucUatus, which has nearly
as many as the Daphnia vetula, and is about the same
size. Their mode of reproduction is the same as in the
Daphniada?, the intervention of the male more than once
not being necessary for fecundating the eggs of the female.
In one species, the Chi/dor us splttericus, Jurine obtained,
by isolating the young successively, fifteen generations ;
and in the Alona quadrangula,ris,\ he followed up the
moultings and generations for nine successive periods.
On the 7th of June he isolated a female, which had eggs ;
8th June, two young ones born ; 9th, it has moulted, and
got two eggs of a clear brown colour ; 1 1 th, eggs are
elongated, eye visible; 13th, a second accouchement has
taken place ; 14th, has moulted, and has two eggs ; 17th,
a third accouchement ; 19th, has moulted, and has three

* In the Bulletin of the 'Ann. de la Soc. Entoraol.,' February 1837, p. 11,
M. Audouiu communicated the fact of his having had several specimens of a
species of Lyuceus from the neighbourhood of Warsaw, sent to him by the
celebrated Waga, and that he had ascertained the existence of male speci-
mens amongst them. He contemplated publishing a memoir on the subject,
but his premature death prevented the accomplishment of his object. 1 am
not aware of the male having ever been noticed by any author since that
time ; but perhaps the species described by me as Pleuroxus hamatits may
prove to be the male of an allied species.

f Monoculits striatm, Jurine.

122 BRITISH ENTOMOSTRACA.

eggs ; 20th, a fourth accouchement ; 21st, moulted, and
has two eggs ; 22d, a fifth accouchement; 23d, moulted,
and has two eggs ; 25th, a sixth accouchement; 26th,
moulted, and has two eggs; 28th, a seventh accouche-
ment; July 3d, moulted, and has two eggs; 8th, an eighth
accouchement ; 9th, moulted, cannot exactly determine
whether it has eggs, the insect is yellow; llth, moulted,
cannot see eggs ; 14th, ninth accouchement, young ones
dead; 15th, mother herself is dead.* The young are
born perfect ; and even before they are ushered into the
world, whilst still in the matrix, we discover the eye and
its accompanying black spot. These insects are said by
J urine to be subject, like the Daplmiadae, to the saddle or
ephippium, and he asserts that in each ephippium there
is only one egg, which is placed in the middle of the
saddle, and makes a projection from it. 1 have never
myself met with an individual having the saddle ; and
in general I have found those which I have kept very
short-lived as compared with the Daphniadu1. The
motion of these insects through the water is somewhat
different from that belonging to the Daplmiadae. Instead
of swimming by short irregular bounds, as these latter
do, they direct themselves by a rapid motion of their in-
ferior antennae, or rami, and legs, straight towards the
point to which they wish to go. This was noticed by
Eichhorn, as already mentioned, who seems to be the only
person who remarks it till the time of Jurine ; and it ap-
pears chiefly perhaps to depend upon the comparative
shortness and position of the rami, for theJJosmina lonyi-
rostris, which has also very short rami, situated as in the
Lynceidse, has the same kind of motion, f The food of
the Lynceidse consists of both animal and vegetable
matter, and while they prey upon animalcules smaller
than themselves, they, in their turn, are devoured in great
numbers by insects larger than they are. According to
Priteliard, (he f 'liydorm sj>//« r/Vv/.v is the choice food of

* .luriiir. HIM. des Muiinc., pp. 153-0.

f M. •!'_'. /'•(>!. .111(1 Hot., ii. H2.

EURYCERCUS. 123

a species of fresh-water Nais, which he calls the Lurco.
"So great is the voracity," he says,* "of this creature, that
I have seen a middle-sized one devour seven Lyncei in
half an hour. Five of these were moving about in the
first cavity, at the end of that time the other two, having
passed into the second, had become exhausted, "f

This family contains seven British genera.

1. EURYCERCUS. — Subquadrangular ; abdomen very
broad, in form of a flat plate, densely serrated.

2. CHYDORUS.— Nearly spherical in shape ; beak very
long and sharp, curved almost into the shape of a crescent;
inferior antennae very short.

3. CAMPTOCERUS.' — Ovoid-shaped ; abdomen long,
slender, and extremely flexible ; serrated.

4. ACROPERUS. — Shell somewhat harp-shaped, termi-
nating inferiorly on the anterior margin in a more or less
blunt point projecting forwards ; inferior antennae rather
long.

5. ALONA. — Shell quadrangular, striated or grooved
longitudinally ; inferior antennse short.

6. PLEUROXUS. — Anterior margin prominent on the
upper portion ; the lower part being truncated, or, as it
were, cut sharp and straight ; first pair of feet very large.

7. PERACANTHA. — Oval-shaped ; lower extremity of
shell slightly curved backwards, and, as well as upper
extremity of the anterior margin, beset with strong,
hooked spines.

Genus 1 — EURYCERCUS. J

LYNCETJS, Miiller, et auctorum.

ETJRYCEKCUS, Baird, Ann. Mag. Nat. Hist, ii ; Trans. Berw. Nat. Club, ii.

Character. — Subquadrangular. Abdomen very broad,
in form of a flat plate, densely serrated. Beak blunt,
slightly curved downwards.

* Pritchard's Micros. Cab , p. 81.

f Vide supra, p. 9.

% From tvpvg, broad ; and KtpKog, a tail.

124 BRITISH ENTOMOSTRACA.

1. EURYCERCUS LAMELLATUS. Tab. XV, figS. 1, 1 a-l.

LYNCEUS LAMELLATUS, Mutter, Zool. Dan. Prod., No. 3396, 1776 ;

Entoinost., 73, t. 9, f. 4-6.
Latreille, Hist. Nat. Crust., 208.
Baird, Trans. Berw. Nat. Club, i, 100.
M. Edwards, Hist. Nat. Crust., iii, 388.
Koch, Deutsck. Crust., h. xxxvi, t. 9.
MONOCULUS LAMELLATUS, Gmelin, Linn. Syst. Nat., 3008, No. 62.

Ma/niel, Eucyc. meth., vii, 733, No. 62,

t. 268, f. 21-3.
Fabricius, Ent. Syst., ii, 498.

EURYCERCUS LAMELLATUS, Baird, Ann. Mag. Nat. Hist., ii, 88, t.2, f .1-8.

1843 ; Trans. Berw. Nat. Club, ii, 150.

This is the largest of all the known species of this
family, being in old specimens fully as large as the
Daphnia vetula.

Shell of an olive colour ; rather square-shaped, ciliated
on anterior margin ; ventricose in centre, and arched on
posterior edge. Beak rather blunt and short.

Superior antennae are stout, solid bodies, somewhat
conical in shape, slightly curved, and terminating in
six short spines, each of which gives out a fine seta or
bristle. They are not possessed of much motion. In-
ferior antennae or rami very short, compared with the
size of the insect, and two-branched ; both branches of
about equal length. The anterior branch has five long
filaments, one from the extremity of first and second
joints, and three from the third ; this joint has also a
short spine. The posterior branch has three long fila-
ments, all springing from the extremity of last joint, and
the first and second have each only a short spine. These
filaments are finely plumose, like those of the Dnphnia
pulcx, and jointed about the middle of their length.

Eye large, contained in its funnel-shaped sheath of
muscles, areolar ; arcola? about twenty in number. The
accompanying black spot is remarkably small, situated
almost directly under the eye instead of in front, and is
somewhat of a square shape.

CHYDORUS. 125

Intestine convoluted (t. XVII, f. A), having one incom-
plete convolution and half another. Lower part of the body
of the animal has a lobe springing out from its edge like
a spur. Setae at the joint of the abdomen finely plumose,
and jointed at about half their length.

Abdomen very broad, lamellar, densely and strongly
serrated on lower edge; sinuated deeply on anterior
margin, and terminating in two stout claws and two
small ones.

The mandibles are strong, rounded towards the ex-
tremity, which is armed with sharp teeth. The first pair
of feet consists of a strong fleshy sort of body, ciliated on
the upper edge, and terminating in five long and strong
filaments, which generally project outside of the shell.
The other feet consist of broad plates, with the branchial
apparatus attached, and resemble a good deal those of
the Daplmia.

The motion of this insect is peculiar ; it generally lives
at the bottom of the vessel in which it is kept, and when
disturbed, it bounds up by rapid short motions in a curved
sort of line, and then returns in the same manner to the
place from where it rose. It is very heavy and slothful
compared with the other genera, and I have frequently
tinned it over two or three times before it has moved.

Hob. — Not uncommon in ponds and ditches, during
the summer months. Near Isleworth, and elsewhere in
the neighbourhood of London. In Yetholm Loch ; and
pool on Bowmont Water, near Yetholm, Roxburghshire.

Genus 2— CHYDORUS.

LYNCEUS, Miiller, et auctorum.
CHYDOKUS, Leach, Supp. Encyc. Brit.

Baird, Ann. Mag. Nat. Hist., ii ; Trans. Berw. Nat. Club, ii.

Character. — Nearly spherical in shape. Beak very
long and sharp, curved downwards almost into the shape
of a crescent. Inferior antennae very short.

126 BRITISH ENTOMOSTRACA.

1. CHYDORUS SPH^RICUS. Tab. XVI, fig. 8.

LYNCEUS SPH^ERICUS, Mutter, Zool. Dau. Prod., No. 2932, 1776;

Entomost., 71, t. 9, f. 7-9.
Latreille, Hist. gen. Crust., 207.
Lamarck, An. s. Vert., v, 128, No. 3.
Desmarest, Cous. gen. Crust., 377.
Baird, Traus. Berw. Club, i, 100.
M. Edwards, Hist. Crust., iii, 386.
PritcJiard, Micros. Cab., t. 8, f. 3.
Koch, Dcutsch. Crust., h. xxxvi, t. 13 (not

h. viii, t. 2.)
MONOCULUS SPH^ERICUS, Gmelin, Linn. Syst. Nat. 3008, No. 60.

Manuel, Encyc.meth.,vii, 732, t. 268, f. 15-17.
Fabricius, Eut. Syst, ii, 497.
Jurine, Hist. Monoc., t. 16, f. 3.
MoNOCULUSiNFUSORius(KleuisterScbildfloh),/S'^r««/-,Eiaim. Insect.

Aust., 536.

EiMorn, Beyt. Naturg., t. 3, f. d*
CHYDORUS MUXLEKI, Leach, Euc. Brit. Supp., art. Aunulosa, 1816 ;

Diet. Sc. Nat., xiv., 541.

CHYDORUS SPH^RICUS, Baird, Ann. and Mag. Nat. Hist., ii, 89, t. 2,

f. 1 1-13,1843 ; Trans. Berw. Nat. Club, ii, 150.

Shell round, smooth, slightly ciliated on anterior
margin, of an olive green colour. Inferior antennae or
rami very short ; anterior branch has four set<r, three
springing from the extremity of the last articulation,
and one from the extremity of the second ; poste-
rior branch has only three from the last joint. Intestine
convoluted, having one complete convolution and halt'
another.

Abdomen jointed, and having two stout claws at its
end; the intestine passing through the joint, and termi-
nating in the anus near the claws.

Eye areolar ; its accompanying black spot pretty large,
and situated just above the root of the superior antenna'.

* Perhaps this may be a new species. MiilliT quotes Iliis figure <>!'
Eichhnni lor his A. (i-i</<j,/fll/ix, but. il .-ippcars to me to lie quite distinct. It
resembles the K/ilm wV/'.v in shape, except that the inferior extremity of the
slu II is pointed. Should it prove a uc\v species, \vc would propose to name it

l-'.x-llhurili.

CHYDORUS. 127

Its motion through the water is more like rolling, as
Jurine describes it, than swimming.

The mandibles, feet, and superior antenna? are very
similar to those of the preceding genus.

According to Pritchard, " the young play near their
parent, and at the approach of danger swim for protection,
within the shell of the mother, which she, conscious of
their feebleness, immediately closes."*

Hab. — Ponds and ditches ; common almost all the
year round.

2. CHYDORUS GLOBOSUS. Tab. XVI, fig. 7.

CHYDORUS GLOBOSTJS, Baird, Aim. and Mag. Nat. Hist., ii, 90, t. 3,

f. 14, 1843; Trans.Berw. Nat. Club,ii, 150.

Shell quite globular, a good deal resembling in form
the preceding species, but more completely rounded, and
nearly six times larger ; striated circularly on exterior
and upper margin, and spotted with small black spots ;
the anterior portion of the shell is of a red hue, with a
large, irregular-shaped, dark band running across the
centre of the shell, and occupying about half its extent.
The beak is extremely long, and at times appears to lie
close to the body.

Abdomen (t. XVI, f. 7 c) elbowed at the joint, and
hollowed out immediately before it, terminating in two
long claws.

Eye large, areolar. Superior antenna large, with seven
teeth, and seven long seta3. Inferior antennse or rami
(t. XVI, f. 7 b) very short and slender ; anterior branch
with four seta?, one from the second, and three from the
last articulation ; posterior branch has only three from
the last joint. First pair of feet large. Intestine con-
voluted (t. XVII, f. B), having one turn and a half.

The motion of this species is very much like that of a
Cypris.

* Micros. Cab., p. 90.

128 BRITISH ENTOMOSTRACA.

Hab. — Pond near Isleworth ; ditch near Richmond ;
June, July, August, and September, but rare, and confined
apparently to small patches. Pond near Bexley Heath,
July. Ornamental water in Regent's Park, July;
T. Rupert Jones, Esq.

Genus 3 — CAMPTOCERCUS.*

LYNCEUS, Muller, ct auctorum.

CAMPTOCERCUS, Baird, Ann. and Mag. Nat. Hist., ii; Trans. Benv. Nat.
Club, ii.

Character. — Ovoid-shaped. Abdomen very long,
slender, and extremely flexible ; much serrated. Beak
blunt, slightly curved downwards.

1. CAMPTOCERCUS MACROURUS. Tab. XVI, fig. 9.

LYNCEUS MACROURUS, Mi'dler, Zool. Dan. Prod., 2397, 1776 ;

Entomost., t. 10, f. 1-3.
Latreille, Hist. Nat. Crust., 207-
M. Edwards, Hist. Nat. Crust., iii, 388.
MONOCULUS MACROURUS, Gmelin, Syst. Nat., 3008, No. 65.

Manuel, Enc. meth.,vii, 733, No. 65, t. 268,

f. 26, 27.

Fabricitts, Ent. Syst., ii, 499.

CAMPTOCERCUS MACROURUS, Baird, Aim. and Mag Nat. Hist, ii, 91,t. 3,

f.5, 6,18-13; Trans. Ber. Nat. Cl.,ii, 150.

Of an ovoid shape. Shell pellucid and whitish, finely
striated or ribbed longitudinally, slightly sinuated and
ciliated on anterior margin. Beak rounded, and rather
blunt. Eye small, but areolar, accompanying black spot
nearly as large as the eye.

Superior antennae rather long and slender, termi-
nating setee long also. Inferior antennae or rami short.
Anterior branch with four long filaments and one short ;
one long, from second articulation ; three long and one

* Ko^Trroc, llrxiblr ; and KV^KOI;. a fail.

ACROPERUS. 129

short, from last; posterior branch has only three long
filaments and one short, from the last joint.

Abdomen (t. XVI, f. 9 «) very long and slender, with
thirteen well-marked serrse, or teeth, on lower edge, and
several smaller ones, terminating in two long and slender
claws ; setae short. This organ, and lower part of body,
is extremely flexible, and the animal can twist it com-
pletely round in a circle, and then unbending it, thrust
it far out beyond the shell.

First pair of feet large.

Intestine convoluted, having one complete convolution,
and half another.

Hob. — Ditch near Richmond. Pond near Smallborough
Green, Hounslow. Highgate ponds. June, July, and
August.

Genus 4 — ACROPERUS.*

LYNCEUS, Saird, Trans. Berw. Nat. Club, i.

ACUOPERUS, Saird, Ann. and Mag. Nat. Hist., ii ; Trans. Berw. Nat.
Club, ii.

Character, — Shell somewhat harp-shaped, terminating
inferiorly on anterior margin, in a more or less blunt
point, projecting forwards. Inferior antennae, or rami,
long. Beak blunt, curved downwards.

1. ACROPERUS HARP^E. Tab. XVI, fig. 5.

LYNCETTS HARPJE, Baird, Trans. Berw. Nat. Club, i, 100, t. 2, f. 17, 1835 .
ACROPERTJS HARP.E, Baird, Aim. and Mag. Nat. Hist., ii, 91, t. 3, f. 7,

1843 ; Trans. Berw. Nat. Club, ii, 151.
LYNCEUS LEUCOCEPHALUS,.£O<?//, Deutsch. Crust., h.xxxvi, 1. 10,1841.

Shell rounded posteriorly, sinuated rather deeply, and
ciliated anteriorly ; terminating in an obtuse point, pro-
jecting forwards; strongly striated, or rather ribbed,
longitudinally and somewhat obliquely, giving the shell,

* From nicpoc, pointed ; and ire pas, extremity.

9

130 BRITISH ENTOMOSTRAC'A.

which is quite transparent, a good deal of resemblance
to a harp. Beak rounded and obtuse.

Eye areolar ; accompanying black spot nearly half the
size of the eye, and rather square-shaped.

Superior antennae of considerable length, the termina-
ting setae being much longer than in the other genera-
Inferior antennae or rami slender, and of considerable
length, each branch provided with three long setse from
the extremity of last articulation only.

The rami and setee together extend almost the length
of the shell, reaching nearly to its inferior extremity.

The upper part of the body of the animal is very
rounded, and crenated on the outer edge.

Abdomen slender, not serrated on under margin, but
marked near the edge with a row of indentations, and
terminating in two claws, which are long and slender.

First pair of feet large.

Intestine convoluted, having one turn, and nearly half
another.

Hub. — Pond in Osterly Park ; ditch near Richmond ;
pond on Bowmont Water, Yetholm, Roxburghshire ;
Dunglass Pond, East Lothian. Summer months.

2. ACROPERUS NANUS. Tab. XVI, fig. 6.

ACROPERUS NANUS, Bttird, Ann. and Mag. Nat. Hist., ii, 92, t. 3, f. S,

1843 ; Trans. Berw. Nat. Club, ii, 151.

Somewhat resembles the last in shape, but is very
small, not the seventh part the size ; is less transparent,
less deeply sinuated on anterior margin, and less pro-
jecting at lower extremity.

The striae or ribs are not so large, and are disposed
in a waved form, obliquely transverse ; anterior margin
ciliated.

Beak rather long, sharper than in the preceding species.

Inferior antennae or rami slender, and rather shorter

ALONA. 131

than in harpce; anterior branch has four setae, one spring-
ing from the second, and three from the extremity of last
joint only.

Abdomen has a gibbons projection about the middle of
the lower margin, and is serrated at extremity. Intestine
convoluted, having one turn, and nearly half another.
One ovum.

In size, this species is about the smallest of the family
that I have met with.

Halt. — Pond at Norwood Green ; and near Sonthall,
Middlesex, June 1841. Rare.

Genus 5 — ALONA.

LYNCETJS, Midler, et auctomm.

ALONA, Baird, Ann. aud Mag. Nat. Hist., ii ; Trans. Berw. Nat. Club, ii.

Character. — Shell quadrangular-shaped, grooved or
striated longitudinally. Inferior antennae or rami short.
Beak blunt, and nearly erect.

1. ALONA QUADEANGULARIS. Tab. XVI, fig. 4.

LYNCEUS QUADRANGTJLARIS, Midler, Zool. Dan. Prod., No. 2393, 1776 ;

Entomost., t. 9, f. 1-3.
Latreille, Hist. Crust., 208.
Baird, Trans. Berw. Nat. Club, 100.
M. Edwards, Hist. Crust., iii, 388.
Koch, Deutsch. Crust., h. xxxvi, t. 15.
MONOCTJLTJS QUADRANGULUS, Gmeliii, Syst. Nat., 3008, No. 61.

Manuel, Enc. meth., viii, 733, t. 268,

f. 18-20.

MONOCTJLUS QTJADRANGTJLARIS, Fabricius, Ent. Syst., ii, 498.
MONOCULUS STRIATTJS (?), Jurine, Hist. Monoc., t. 16, f. 1, 2.
ALONA QUADUANGULABIS, Baird, Ann. and Mag. Nat. Hist., ii, 92, t.3,

f.9-ll,1843;Trans.Berw.Nat.Club,ii,151.

Nearly quadrangular-shaped. Shell transparent, of a
deep-brown colour ; strongly ciliated on anterior margin,

132 BRITISH ENTOMOSTRACA.

cilia long ; striated or ribbed longitudinally, the ribs
rather distant. Beak rather blunt. Eye areolar.

Superior antennae conical-shaped ; inferior, or raini
(t. XVI, f. 4 b], short, the setae also being short ; anterior
branch having four, one from second and three from last
articulation; posterior branch has three from last joint only.

Upper part of body rounded, as in Acroperus harpa

Abdomen (t. XVI, f. 4 c] rather narrow, sinuated near
extremity, and serrated for about half its length on the
under edge, the serras or teeth at extremity being the
largest. Terminating claws long.

Intestine convoluted once, and nearly a half, but not
so distinctly visible as in the other genera.*

Hab. — Ditch near Richmond ; pond at Osterly Park ;
and near Hounslow. In the Pease-burn, Cockburnspath.
Pool on Bowmont Water, Yetholm, Roxburghshire.

2. ALONA RETICULATA. Tab. XVI, fig. 3.

ALONA RETICULATA, Baird, Ann. and Mag. Nat. Hist., ii, 93, t. 3, f.12,

1813 ; Trans. Berw. Nat. Club, ii, 151.

In size this is perhaps the smallest of all the species of
this family, being still smaller than the Acrop&rus nanus.

Shell of a quadrangular shape, rounded a little poste-
riorly, and nearly straight on anterior margin, which

* I had some doubts at first as to this being identical with the Nonoculus
strialus of Jurine. In his figure the beak is blunter, and the abdoiueii
shorter and rounder-shaped than in my specimens, lie gives it the mime
xt,-iiitns with a doubt ; and remarks, " if this species be the trnncatus of
Midler, as we may presume it is, it must be confessed that its specific name
is improper; for the shell is not truncated, it is obliquely striated and
strongly ciliated" (1. c., p. 154). It is evident that Jurine could never hu\r
seen the truncatus of Miillcr, and the qwtd/rangularis seems also not to
have been known to him ; for the difference between this species and the
truncatus is so great and evident, that they cannot be mistaken for each
other; while the similarity between it and the quadrangularis is so decided,
that notwithstanding the slight discrepancies mentioned above, 1 have now
little or no hesitation in referring them both to (lie same species.

ALONA. 133

appears free from cilia. The lower margin is obtuse, and
the whole shell is very closely reticulated.

Beak prominent and long, projecting upwards, rather
blunt. Eye large for size of animal, areolar.

Inferior antennae or rami rather slender ; anterior
branch provided with four setae, one short from second,
and three long and stout, from last articulation ; posterior
branch has three from last joint only.

Abdomen rather tapering towards the extremity, and
serrated on inferior margin.

Intestine convoluted, but it is not easily seen from
reticulated surface of shell. One ovum.

Hob. — Pond near Southall, Middlesex, July 1841 ;
September 1849.

3. ALONA OVATA. Tab. XVI, fig. 2.

Ovately globose ; transparent ; shell striated ; striae
waved longitudinally.

Superior antennae short. Beak of carapace or shell
rather short and blunt.

Anterior edge of shell densely ciliated. Eye areolar,
anterior black spot large.

The head is erect, as in A. quadrangularis.

Intestine convoluted.

Tail hollowed out a little, about the centre of its in-
ferior edge, then bulges out, and is armed with short
spines, and finally terminates in two short, curved claws.

In size it is rather larger than the A. quadrangular is.

Pond on Blackheath, April 1848.

134 BRITISH ENTOMOSTRACA.

Genus 6 — PLEUROXUS.*

LYNCEUS, Mi'dler, et auctoru/n.

PLEUROXUS, Baird, Ann. and Mag. Nat. Hist., ii; Trans. Berw. Nat. Club, ii.

Character. — Anterior margin prominent on upper
portion, the lower part being truncated, or, as it were,
cut sharp and straight. First pair of feet very large.
Beak sharp, curved downwards.

1. PLEUROXUS TRIGONELLUS. Tab. XVII, fig. 3.

LYNCEUS TRIGONELLUS, Miiller, Zool. Dan. Prod., No. 2395, 1776 ;

Eutomost., t. 10, f. 5, G.
Latreille, Hist. gen. Crust., 205.
Lamarck, An. sans Yert., 123, No. 2.
Baird, Trans. Berw. Nat. Club, 100.
M. Edwards, Hist. Nat. Crust., iii, 387.
Koch, Deutsch. Crust., h. xxxvi, t. 1 4.

MONOCULUS TRIGONELLUS, Gmelin, Linn. Syst. Nat., 3003, No. 63.

Minntel, Eucyc. meth., vii, 733, No. 63,

t, 268, f. 24, 25.
l-'it/H-iciws, Ent. Syst., p. 498.

PLEUROXUS TRIGONELLUS, Baird, Ann. and Mag. Nat. Hist,, ii, 93, t. 3,

f. 1 3, 1843 ; Trans. Berw. Nat, Club, ii, 151.

Shell somewhat triangular-shaped, and transparent ;
gibbous on upper portion of anterior edge for about a
third of its length, the lower two thirds being truncated,
or, as it were, cut obliquely with a straight, sharp edge,
and ciliated. Posterior margin gibbous also, and sinuated
near lower extremity, which terminates in a square point.

Beak long and curved, sharp-pointed. Eye areolar.

Inferior antennae or rami short and slender. The an-
terior branch has four setas, one from first articulation,
one from second, and two from last. Posterior branch
has three setae, all springing from last joint.

* I'Yum TrXtt'por, a side ; and o£i'c, .sharp.

PLEUROXUS. 135

Abdomen (t. XVII, f. 3 c) gibbous for latter half, and
serrated.

First pair of feet (f. 3 b} very large ; the pediform organ
of Midler being the first pair of feet.

Intestine convoluted, having one turn and nearly half
another.

Hab. — Pond near Copenhagen Fields, Osterly Park,
Norwood Green, and Southall, Middlesex, June to
October. Pond at Fouldean, Berwickshire; and at
Yetholm, Roxburghshire.

2. PLEUROXUS UNCINATUS. Tab. XVII, fig. 4.

Shell slightly triangular in shape, transparent, and
fluted; gibbous on upper portion of anterior edge, and
less straightly cut on lower portion of anterior edge
than in preceding species. At the inferior angle of this
margin there are three sharp spines, and the margin itself
is ciliated. The posterior margin is rounded and sinuated
at the lower part, but not so deeply as in trigondlus,
and the square point at extremity is shorter than in it.

The beak is long and curved ; but the tip, instead of
being curved downwards as in preceding species, is
turned up.

The antennules, antennse, feet, and abdomen, with in-
testine, are similar to those parts in trigonellus, and the
animal is nearly of the same size.

The ova, in all the specimens I have met with, are only
two.

The young exhibit the remarkable turned-up beak and
the spines on inferior extremity of shell as soon as born.

Hab. — Pond between Hanwell and Southall, Middlesex,
September 1849.

136 BRITISH ENTOMOSTRACA.

3. PLEUROXUS HAMATUS. Tab. XVII, fig. 5.

LYNCEUS HAMATUS, £aird,Trans. Berw.Nat.Club,100,t.2,f.l8,1835.
PLEUBOXUS HAMATUS, Baird, Ann. and Mag. Nat. Hist., ii, 94, t. 3,

f. 14, 1843; Trans.Berw. Nat. Club, ii,151.

About half the size of the preceding species.

Shell truncated anteriorly, and ciliated; extremely trans-
parent ; upper part gibbous.

Beak blunter and stronger than in trigonellus.

Inferior antennas or rami with three setee in each
branch.

Abdomen gibbous, not serrated, terminated by two
claws or hooks.

First pair of feet large, each furnished at extremity with
a strong claw or hook turning upwards.

Intestine convoluted.*

Hab. — Yetholm Loch, and pool on Bowmont Water,
near Yetholm Bridge, Roxburghshire, July 1835.

Genus 7 — PERACANTHA.!

LTNCEUS, Midler, et auctorum.

PERACANTHA, Baird, Ann. and Mag. Nat. Hist., ii.

Character. — Oval-shaped ; the lower extremity of shell
slightly curved backwards, and, as well as the upper ex-
tremity of anterior margin, beset with strong, hooked
spines. Beak sharp, curved downwards.

' I have only once met with this speoics. It may perhaps l>e the male
of triijiH/i'ltt/!*, the clicliform nature of the first pair of feet having a consi-
derable resemblance to the structure of that organ in the male Daplmia,
and more especially in tin1 male of the Estheria, as represented by Joly in
his description of the Isaura ci/i-lmloides, 'Ann. Sc. Nat.,' 2d series, xviii, 1843.
t From TTtpac, extremity; and aicai'Oa, spine.

PERACANTHA. 137

1. PERACANTHA TRUNCATA. Tab. XVI, fig. 1.

LYNCEUS TRUNCATUS, Milller, Eutomost., 75, t. 11, f. 4-6, 1781.
Latreille, Hist. Crust., 206.
Baird, Trans. Berw. Nat. Club, 100.
M. Edwards, Hist. Crust., iii, 388.
Koch, Deutsch. Crust., h. xxxvi, t. 11.
MONOCULUS TRUNCATDS, Gmeliti, Linu. Syst. Nat., 3008, No. 64.

Manuel, Euc.metk.,vii,733,t.268, f. 30-34.
Fabricius, Ent. Syst., 498.

PERACANTHA XRUNCATA, Baird, Ann. and Mag. Nat. Hist., ii, 94, t. 3,

f. 15, 1843; Trans.Berw. Nat. Club, ii, 151.

Shell nearly of an oval form, the lower extremity
having a curved projection backwards, and provided with
a number of pretty strong spines, about seventeen in
number, the last three of which are curved backwards.
On the upper extremity of anterior margin there are
about an equal number of spines, the upper ones being
curved upwards. These are partly concealed by the cilia,
which densely cover the anterior margin of the shell.
The shell is striated longitudinally.

Beak rounded and sharp-pointed, rather long.

Eye areolar; accompanying black spot of a square
shape.

Superior antennae conical-shaped ; inferior, or rami
(f.l«), short. Anterior branch furnished with five setae; one
from first, one from second, and three from last articula-
tion. Posterior branch has three setae, all from last joint.

Abdomen rather gibbous on lower edge, and on latter
half has about eight spines, and terminates in two stout
claws. First pair of feet large.

Intestine convoluted (f. 1 6), having one round and a
half. Two ova.

Hab. — Pond at Osterly Park, ditch near Richmond,
pond at Southall, Middlesex ; summer months. Pool on
Bowmont Water, Yetholm, Roxburghshire.

138 BRITISH ENTOMOSTRACA.

LEGION II— LOPHYROPODA.*

LOPHYROPA, Latreille, Cuv. Regne An., iv, 150.

Say, Journ. Acad. Nat. Sc. Philad. i.
LOPHYROPA and OSTRAPODA, Desmarest, Cons. gen. Crust.
LOPHYROPODA, Leach, Diet. Sc. Nat., xiv, 521.

/. K Gray, Synops. Brit. Mus., 1842.

Burmeister, Beitr. zur Naturg. der Raiikenfusseu.
BRANCHIOPODES FRAXGLS (pars), Lamarck, Hist. An. s. Vert., v.

Character. — Mouth furnished with organs fitted for mas-
tication. Branchiae few, attached to the organs of mouth.
Body having an envelope, either in form of a buckler,
inclosing head and thorax, or in shape of a bivalve shell,
inclosing the whole animal. Feet few in number, not
exceeding five pairs. Articulations more or less cylindri-
cal, and serving the animal for the purpose of locomotion.
One eye. Two pairs of antennae ; one pair of which are
used by the animal as organs of motion.

ORDER I— OSTRACODA.f

OSTRACODA, Latreille, Hist. Nat. Crust., 1801 ; Cuv. Regnc Anini..

iv, 151.

Baird, Mag. Zool. and Bot., i; Trans. Berw. Nat. Club, ii.
OSTRACINS ou BiTESTACi's, Dvm&ril, Zoologie Analytiquc, 1S06.
OSTRAPODA, Straus, Mein. Mus. d'Hist. Nat., vii.
CYPROIDES ou OSTRACODES, M. Edwards, Hist. Nat. Crust., iii, 393.
CROPHYROPODA B., Burmeister, Organization of Trilobites (Ray Soc.

edit.), 34.
CYPRIDAI i. \ vel OSTRACODA, Dana, Proc. Amer. Acad. Sc., 1849.

Character. — Hody inclosed entirely in a covering of
two valves, resembling a bivalve shell. Posterior jaws
branchiferous. No external ovary. Firt two and three
pairs, adapted for progressive motion.

Tins order contains three families, Cypridae, Cytheridae,
;ni(l Cypridinadae.

I'Yom \o<j>vpot;, havniL1- •-Mil' hairs, anil n-oi't. foot.
f I'rom nnrpaKoi', ;\ slirll.

CYPRID.E. 1 39

Family I— CYPRIOTE.

CYPRIS, Mi'dler, et auctorum.

CYPROIDES (pars'}, M. Edwards, Hist. Nat. Crust., iii, 393.

CYPRIOTE (pars), Baird, Traus. Berw. Nat. Club, ii, 153.

Character. — Two pairs of antennae ; superior long, with
numerous joints, and a pencil of long filaments ; inferior
stout and pediforai. Eye single. Feet two pairs.

Bi&liograpMcal If is for?/. — Baker is said to be the first
author who has taken any notice of any of the animals of
this family. In his work, ' Employment for the Micro-
scope,' 1753, an anonymous correspondent describes at
some length an insect which has a bivalve shell, somewhat
resembling a small fresh-water mussel, and gives a figure
of it lying on its back, which is barely sufficient to enable
us to discern that it is a Cypris.

Straus complains that he cannot discover any mention
made of the genus by Baker, either in the edition of
1743 or 1744, which are the only editions he has been
able to see ; neither is there, he says, any plate 1 5 in either
of these editions. He quotes the wrong work, however,
having referred to the ' Microscope made Easy,' instead
of Baker's second work, ' Employment for the Micro-
scope', in which he would have found the insect referred
to by Miiller.

Linnaeus, in his 'Fauna Suecica,' 1746, describes a
species in a few general terms ; and, in the seventh
edition of the ' Systemse Natura,' 1748, he mentions a
species under the name of Monoculus concha pedata, but
gives no description. In the tenth edition of the same
work, 1760, he gives the description, as taken from the
' Fauna Suecica,' but names it Monoculus conchaceus.

Joblot. in his ' Observations d'Histoire Naturelle faites
avec le Microscope,' 1754, describes a species, which he
calls poisson nomine Detouche, or Grain de Millet, from
its resemblance in size and colour to that species of seed,
and gives a figure of it.

140 BRITISH ENTOMOSTRACA.

Ledermuller, in his work, ' Microscopischen Gemiiths-
und Augen-ergotzung,' 1760, gives several figures of a
species of Cypris, and says, he has frequently seen them
in copulation.

Poda, in his 'Insecta Mussei Grsecensis,' 1761, gives
one species, the Monoc. conchaceus of Linnaeus, quoting
merely his description.

Geoffrey, in his ' Histoire des Insectes,' 1762, after a
few general remarks upon the Monoculi, describes shortly
two species of the genus, but gives no figures of them.

Miiller, in his ' Fauna Insectorum Fridrichsdalina,'
1764, only mentions one species under the name and
description given by Linnaeus, in his ' Faun. Suec. ;' but
in 1771 he published an admirable paper in the 'Phi-
losophical Transactions' (attributed by M. Straus to
Mr. Bennet, but only communicated by him), in which he
gives an excellent account of two species in particular,
with many details of their anatomy and habits, and con-
cludes by giving a list of nine species, which he had at
that time discovered, including them all, however, under
the name of Monoculus. In his ' Zoologiae Danicse Pro-
dromus,' 1776, he first established the genus Cypris,
as well as the other genera of Entomostraca, all of which
had until then been constantly described under the general
name of Monoculus.

Fabricius, in his ' Systema Entoniologia?/ 1775, gives
Linna3us's species, the Monocuhts conc/taceus ; and De
Geer, in his ' Meinoires pour servir a 1'llistoire des
Insectes,' 1778, describes one or two species, though he
calls them only varieties of the same, and adds a few
details concerning them.

In 1785 appeared the 'Entomostraca' of Miiller, with
copious details and descriptions, and pretty accurate
figures of all the species already shortly noticed in his
' Zool. Dan. Prod.,' and at the end of his paper in the
' Philosophical Transactions,' which paper is also reprinted
in French, at the commencement of this excellent work.
Up to the time that Miiller undertook the working out

CYPRIOTE. 141

the species of this genus, our knowledge of them was,
indeed, scanty. The descriptions found in the authors I
have already quoted previous to him were so superficial,
that even when illustrated by figures, which were also
generally very bad, there was no possibility of distinguish-
ing what species they meant to describe. This difficulty
may be readily seen, upon inspecting the synonyms given
by Miiller, and then referring to the authors quoted by
him, where we can easily observe that he himself has
made several mistakes in such references — neither the
description nor figures of such agreeing with his. For
instance, under the species pub era, he refers to the Mono-
culus concliaceus of Linn gens, with the description which
that author gives in his 'Fauna Suecica,' "An tennis
capillaceis multiplicibus, testa bivalvi ;" a description so
very general, that it answers equally well to any or all of
his eleven species. He also refers to Joblot for the same
species ; but from the representation which that author
gives, as well as from his description, it appears to me
that it bears a much closer resemblance to Midler's Can-
dida ; and the reference to De Geer is equally faulty, as it
is evident that fig. 5, and figs. 6, 7, both of which are
quoted by Miiller as tlaepu&era, are in reality two distinct
species ! In determining the species, therefore, we must
consider the researches of the various authors previous to
Miiller as of little or no use whatever. Indeed, after
Mailer's time, all the authors who have taken notice of
this family have done little else but copy him till the
appearance of Straus's paper, and the work of Jurine. For
instance, Gmelin, in the 13th edition of the ' Syst. Nat.,'
1788, not only quotes Miiller' s species, but gives his
erroneous references also, adding one or two of his own.
He gives, however, two additional species, which Miiller
has not ; and Manuel, in his article Monocle, in the
' Ency. meth. Hist. Nat.,' vii, 1792, after a few general
details, copies the same species that Gmelin gives ; while
Fabricius, in his cEnt. Syst.,' 1793, gives the eleven
species, which Miiller describes, retaining, in addition to
this, Gmelin's erroneous synonyms.

142 BRITISH ENTOMOSTRACA.

Bosc, in his ' Hist. Nat. des Crust,' edit. Buffon, par
Deterville, 1802, gives a very interesting account of this
genus, as does also Latreille, in his ' Hist. Nat. des Crust,
et Ins./ edit. Buffon, par Sonnini, 1802; but they only
mention Midler's species.

Ramdohr in 1805 published his little work on the
Monoculi, * in which he gives some very excellent details
concerning the anatomy of the Cypris, accompanied by
some very good figures ; but his work does not seem to
be known to almost any of the succeeding naturalists
who have written upon the Cypris. He only describes
in this work the Cyjjris striyata of Miiller; but in 1808,
in a paper in the ' Magaz. Gesell. Nat. Berlin,' he de-
scribes at considerable length three additional species
which had not been noticed before.

M. Daudebart de Ferussac fils, in a memoir in the
' Ann. du Mus. d'Hist. Nat.,' vii, 1806, describes one new
species, and Risso, in his ' Hist. Nat. des Crust, des Env.
de Nice,' 1816, two others; but though these additions
were made to the number of known species, and although
Latreille, in Cuvier's ' Regne Animal,' 1817, and Lamarck,
in his ' Hist. Nat. des Anim. sans Vert.,' 1818, give a
variety of details relating to the genus generally, little real
knowledge concerning the anatomy of the inhabitants of
the tiny shells was conveyed to us (for Ramdohr's work
and paper seem to have attracted scarcely any notice),
till M. Straus published his admirable paper on the
genus Cypris, in the seventh volume of the ' Mem. du
Mus. d'Hist. Nat.,' 1821 ; containing a most elaborate
;m;itomieal description of the genus, with a notice, and
figures of three new species, not described by Miiller.

About the same period as Straus read his paper before
the Academy, appeared ,) urine's splendid work on the
Monoculi, replete with interesting details of the genus
generally, and with beautiful figures of eighteen species.
But we find no reference made by either of these authors
to the previous labours of Ramdohr.

"•• P>ryt. /.in- Naturg. Dents. Mouoc. Artcn,

CYPRIDyE. 143

Desmarest, in his ' Consid. gen. sur les Crust./ 1825,
although he gives a very good account of the different
genera, taken chiefly from Straus and Jurine, with an
account of twenty-one species, takes no notice of him
either; but Latreille, in the last edition of the 'Regne
Animal,' 1829, notices his memoir, with all due approba-
tion, and has thus contributed much to disseminate the
knowledge of his researches. Up to that period we know
of no original memoir upon this genus having been pub-
lished in this country ; Leach's article on the Crus-
tacea, in the 'Edinburgh Encyclopaedia,' containing no
details whatever, and only taking notice of one or two
species.

In ] 835 I published a description of nine new species
in the 'Trans. Berw. Nat. Club;' and in 1837, in the
' Magazine of Zoology and Botany/ I gave two additional,
all natives of this country. In the ' Transactions of the
Entomological Society/ vol. i, Mr. Templeton has de-
scribed two new species in the Mauritius ; and Koch, in
the ' Deutschlands Crustaceen/ 1837, 1838, has described
and figured no less than twenty-one new species, though
I am of opinion that several of them had been previously
described, and others are mere varieties. In 1841, Mr.
Haldeman, in the ' Proceedings of the Acad. of Nat. Sc.
at Philadelphia' has shortly described and figured in
outline two others, found in America. M. Lucas describes
another found by him in Algeria.

Anatomy and Physiology. — Ramdohr, Jurine, and
Straus all differ in many respects in describing the ana-
tomy of the genus Cypris, both as regards the nomen-
clature and the use of the parts. The last author who
has described them anatomically is M. Edwards ; and as
his definition of the organs of locomotion, &c. are more
consonant with our knowledge of other Entomostraca,
we shall follow him, taking the details, however, chiefly
from Straus, whose memoir stands pre-eminent amongst
those of his fellow-labourers.

144 BRITISH ENTOMOSTRACA.

The body of the animal is completely inclosed within
a shell of two valves, of a horny-cretaceous substance,
which in general appearance closely resembles that of a
very small mussel, so much so that, as Midler remarks, a
person at first sight of this insect would suppose that it
was a parasite inhabiting the shell of some small mollusc.
The substance of these valves is compact and very brittle,
and seems to be endued externally with a species of
varnish to protect them from the action of the water, as
whenever they rise to the surface the shell becomes per-
fectly dry, and floats there in spite of the animal's struggles
to again immerse itself. The valves are open in their
whole circumference, except in the middle third of the
dorsal surface, where they are united by a ligamentous
hinge and muscles, by which the animal can open and
shut the shell at pleasure. About the middle of each
valve in most species are to be seen a number of small
lucid spots, the use of which I do not know. Miiller
has taken notice of them in the pvbera, and asks " an
ovula?" but there is no connexion between them and the
ova. No other author has mentioned them ; they are to
be met with perhaps in all the species.

The body of the insect (t. XVIII, f. \d] consists of two
rounded portions of unequal size, connected together by
a narrow space, and having on their upper surface a
transparent body, which is the matrix. From the anterior
or thoracic portion spring the two superior antennas, im-
mediately above which is situate the eye, the inferior
antennae, the organs of the mouth, and the first pair of
feet. From the posterior or abdominal portion spring
the second pair of feet and the tail.

The eye is single, fixed, and in the form of a black
sessile tubercle, in which we can discover no traces of
crystallines.

The superior antennae are inserted immediately below the
eye, and have their origin near each other (t. XVII, f. \b}.
In general they consist of seven articulations,* from the

* Jurino says eight.

CYPRIOTE. 145

three or four terminating ones of which arise several

O

pretty long filaments, which vary in number in the dif-
ferent species. Whenever the animal moves, it invariably
puts these organs into rapid motion, dilating and bringing
together again the long filaments, and waving them to
and fro with great rapidity. They are thus considered
by Miiller and Straus to act as true fins, and to be the
principal organs of progressive motion. Jurine, however,
says that, from their position in the anterior part of the
body, and from their motions being thus confined by the
opening of the shell, they cannot be considered as acting
the part of true fins, and that their use in progressive
motion is by no means equal to that of the inferior an-
tennae, called by him the anterior feet. In the larger
species we see these filaments to be beautifully plumose,
a circumstance which has never been pointed out by any
of the various authors who have written upon the genus,
and which strengthens Latreille's suggestion that they
may act as respiratory organs, as well as the branchial
plates of the jaws. The inferior, or second pair of antennae
(t. XVIII, f. 1 c), arise immediately beneath the others;
they are very strong, and resemble in appearance feet as
much as antenna? : indeed, they have almost invariably
been considered and described as the first pair of feet.
Their position, however, in front of the mouth and organs
of mastication, as in the other genera of Entomostraca,
and their resemblance to the inferior antennas of the
Cyclopidae, warrant us, along with M. Edwards, in con-
sidering them as antennae. They consist each of five
articulations:* two belonging to the basilar portion, short,
and directed downwards ; a third, longer, directed for-
wards ; and two terminating joints, the first of which, in
most of the species, gives off at its lower extremity a
bundle of setae, which are frequently plumose ; and the
last being terminated by several tolerably strong hooked
spines or claws. This pair of antennae, therefore, by

* Jurinc says eight.

10

146 BRITISH ENTOMOSTRACA.

this organization is fitted for both swimming and walking,
the filaments assisting in the former, and the hooked claws
at the extremity aiding in this latter purpose, enabling
them to seize hold of the plants, &c. among whieh they
li\e, and thus walk from place to place. Latreille con-
siders these long filaments as acting, along with those of
the superior antennae, the part of respiratory organs.

The mouth is situate in the inferior surface of the an-
terior lobe of the body, and consists of a lip, an inferior
lip, a pair of palpiferous mandibles, and two pairs of jaws.
The lip is composed of a large piece, shaped somewhat
like a hood, forming a projection which advances between
the two inferior antenna:', and is fixed to the body by four
long apophyses. The inferior lip is elongated, triangular,
and movcable; is articulated with the lip, and has at its
extremity two curved apophyses to articulate it with the
second pair of jaws.

The mandible (t. XVIII, f. 1 d} is very large, and is
formed of two pieces. The larger, or mandible properly so
called, is terminated at its superior extremity by a point, and
at the lower or incisive extremity by five pretty strong teeth.
The other piece is in form of a palpus, which issues from
about the middle length of the proper mandible, and
consists of three joints provided with several set;r. The
first joint has near its base a very small branchial plate
terminated by five digitations. This palpiform part of
the inaudible is the second pair of feet of Jurine, the
barbillon of Miillcr; the use of \\hich, both agree, is to
cause a current of water towards the mouth, carrying
with it the particles destined for the animal's food. The
first pair of jaws (t. XVIII, f. 1 f) have for their base a
large square plate, furnished at anterior extremity with four
fingers, the superior of which is of two joints, the other
three having only one each, but all terminated by several
long hairs. From the external edge of this plate, forming
the base, arises a large, elongated, branchial plate (f. lr*),
which gives oil' from the superior crescent ic-shaped edge'
a row of nineteen long spines, arranged like the teeth of

. 147

n comb. The square plate with its fingers must be
Jurine's third pair of feet ; though, if so, the figure which
this author gives of these organs, as well as of his second
pair of feet (the palpi of the mandible of Straus), is de-
cidedly incorrect.* The second pair of jaws is much smaller,
and is articulated on to the posterior angle of sternum,
by means of the two curved apophyses at its extremity
(t. XVIII, f. I/). Each jaw consists of two flattened
joints, the latter of which has several stiff hairs at its
extremity, and from its external edge gives off a rounded
finger, which Straus says he thinks must be considered
as a palpus.

There is much discrepancy amongst the several authors
I have so frequently mentioned as to the number of feet.
Miiller and Ramdohr assert there are four, and the former
remarks upon the singularity of an insect quadruped.
Straus enumerates six ; while Jurine says there are eight, f
M. Edwards however restricts, very properly, the number
to two pairs. The first pair (t. XVIII, f. 1 g) is slender,
cylindrical, and composed of five articulations ; the last
of which is terminated by one long curved hook. The
basilar joints of these organs are directed backwards ; the
succeeding joints downwards, and the terminating ones
forward. The second pair (t. XVIII, f. 1 Ji) arises imme-
diately behind the first, and consists of four articulations,!
the last of which is terminated by two short hooks, and
has a filament thrown back from its extremity like a spur.

* He seems to have been ignorant of the existence of the branchial plate,
as he asks, " If it be true that the branchiae be the first character of the
Crustacea, where shall we place them in these Monoculi ? In the antennae,
feet, or tail ? We cannot give a preference to any one of these parts over
another."

f Miiller was not aware of the existence of the organs which Straus calls
the third pair of feet. Ramdohr was, but considers them as connected with
the male organs of generation ; while Jurine says that they are organs arising
from the matrix, the use of which he does not understand. In addition to
the first and second pairs of Miiller, Ttamdohr, and Straus, Juriue considers
the organs which Miiller calls the " barbillons," attached to the mouth (the
palpi of the mandibles of Straus) and the branchial plate of the upper jaw,
as two additional pairs of feet.

J Straus says five.

148 BRITISH ENTOMOSTRACA.

Tlicy arc curved upwards and backwards, and are always
contained within the shell, never being extended. Their use,
according to Straus, is to support the ovaries." The pos-
terior portion of the body or abdomen (t. XVIII, f. 1 i)
is conical-shaped, terminating in two lengthened stalks,
each of which gives off at the extremity two short hook .
with a third implanted on the upper edge, a little above
them. This abdominal portion of the body is unattached,
and possesses much freedom of motion, the animal ex-
truding it from the shell at pleasure. One great use of
it seems to be to clean the interior part of the shell, which
its length and mobility fit it well for; but Straus asserts
that the object of this organ is for depositing the eggs.
The anatomy of the internal parts of the body is more
difficult to make out distinctly.

The alimentary canal, according to Straus, consists of
a short, narrow oesophagus, a large oblong stomach, occu-
pying the whole of the dorsal region of the body, and a
simple intestine nearly as large as the stomach, becoming
narrower towards the posterior extremity, and opening
bv an anus between the two stylets which form the tail.
The ovaries are two large, simple, conical \essels, placed
externally upon the posterior portion of the body, and
open one at the side of the other into the anterior part of the
extremity of the abdomen, where they communicate with
the canal formed bv the tail or abdomen. There is auot her

«/

organ, the use of which is not so well ascertained. It is
a large and conical mass, situate above the articulation of
the mandibles, of a granulated structure apparently, and
of a light colour. Straus says, that as he could not see
e\actl\ its termination, he is ignorant of its use, but sup-
poses that it must be either the salivary glands, or the
testicle.

The heart and nervous system have as yet escaped
observation. The animals of this lamily are all inhabitants

* Jurinc considers them as somewhat mimn-lril \\illi llic iiuilrix, Iml
says lie is ignorant of llirirusc. Tlir liirmv \\hidi he t;i\rs of Ilirm is \rry
incorri <•'

CYPRID.E. 149

of fresh water, and are to be found in every pond and
ditch where the water remains stagnant, but not putrid.

They are not so prolific as the Cyclopidce, but in some
of the larger species we can count sometimes, according
to Jurine, as many as twenty-four eggs. The males
have never yet been discovered, and the act of copu-
lation has never been witnessed by any author, with
the exception of Ledermiiller, who says he has seen them
in the act, and gives a representation of them in that
state. I have frequently witnessed two individuals in
much the same situation as those figured by Ledermiiller,
but it did not appear to me that they were at the time
engaged in copulation ; and as neither Miiller, De Geer,
Jurine, nor Straus have ever witnessed them in the act,
Ledermiiller must in all probability have mistaken the
nature of their junction. Straus states that every spe-
cimen he has examined has been laden with eggs, which
makes him ask, " Are they hermaphrodites ? or do the
males only appear at some particular season of the year?"

Jurine has collected eggs immediately after they had
been deposited by the parent animal, has isolated them,
and seen them safely hatched. He has then isolated the
young after they were hatched, and found that they
became pregnant without the intervention of the male.
They must either, therefore, be hermaphrodites, or, as in
the Daphniadse, one copulation suffices not only to im-
pregnate the female for life, but the succeeding genera-
tions also ; as the males of the Daphniadse, too, appear only
at particular seasons of the year, and in small numbers,
it is probable that the males of the Cypridae will be found
hereafter by succeeding observers. The eggs are perfectly
spherical, and are deposited by the animal upon some solid
body, such as part of a plant, &c., in a mass, which at
times, says Straus, consists of some hundreds from various
individuals, the mother fixing them to the surface of the
body on which they are deposited, by means of a glutinous
kind of substance, and then leaving them. When the
animal is about to lay, it fixes itself, says Jurine, so firmly

150 HKLTISH ENTOMOSTKAi \.

in a place of security, that it cannot be displaced by any
agitation of the water, and is occupied twelve hours in
the operation. The eggs remain about four days and a
half before they are hatched, and then the young at once
assume the appearance of the perfect animal, though
varying a little in shape of shell. According to J urine
they undergo several moultings before they arc fit to pro-
create their species ; the frequency of these moultings
depending upon the season of the year, and being in
proportion to the gradual development of the animal.
Moulting continues to take place in the adult after each
laying, and as the shells of these little animals get very
frequently covered with dirt and moss, which adhere close
to them, this change of covering becomes a useful act to
disembarrass the animal of a shell now disagreeable to it ;
while in the young, their development can only take place
by getting rid of the shell as soon as it becomes too small
for the body contained within. The renewing of the
shell forms a fine example of the process of exuviation, as
naturalists term it. The change which takes place being
most complete ; for not only does the shell itself fall off,
but the animal even casts off the internal parts of the
body, the fine pectiniform branchhe, and the minutest
hairs clothing the seta; of the antenna1, &c.

The food of these little creatures consists of dead animal
matter, Conferva:', &c. Straus says he never saw them
attack living animals when they werewell and strong, but he
has frequently seen them attack worms, &C., when wounded
and weak. Though dead animal matter was their choice,
they will not, he adds, eat it when putrid. They no doubt
also prey on each other, as 1 have often observed indivi-
duals of one species devouring eagerly the dead carcases
ol'speeies diHerent from themselves. When the ponds and
ditches in which they live, dry up in summer, they bury
themselves in the mud, and thus preserve their lives as
long as the mud retains any moisture, becoming active as
ever \\lien the rain falls and again overllous their habita-
tions. After Long-continued drought, houever, when the

CYPRIS. 151

mud becomes very dry and hard, they perish; but the
eggs do not perish along with the parents, for they can be
hatched in four or five days after being placed in water.

These little creatures seeni to be very lively in their
native element, being almost constantly in motion, either
swimming about rapidly by the action of their antennae,
or walking upon the plants and other solid bodies floating
in the water. Instead of being fixed to one place, and
condemned to live amidst eternal darkness, like the mol-
luscous animals to which they bear such resemblance in
external covering, c:they" to use the words of Miiller,
" by opening their valves, enjoy light, and move at their
will, sometimes burying themselves in the mud, some-
times darting through the water, the humid air of their
sphere. If they meet any unforeseen object, they conceal
themselves all at once in their shells and shut the valves,
so that force and address seek in vain to open them."

This family contains two Genera.

1. CYPRIS. — Inferior or pediform antennas provided
with a pencil of long hairs or filaments. Animal swim-
ming freely in the water.

2. CANDONA. — Inferior or pediform antennas destitute
of the pencil of long hairs or filaments. Animal creeping
on the ground or upon plants.

Genus 1 — CYPRIS.

CYPKIS, Miiller, Latreille, M. Edwards, Dana, fyc.
MONOCULUS, Lintieeus, Manuel, fyc.
MONOCLES A COQUILLE BIVALVE, Jurine.

Character. — One eye. Two pairs of feet ; one pair
always inclosed within the shell. Abdomen terminated
by a long, slender, bifid tail. Posterior or pediform an-
tennae furnished with a bundle of long setae, generally
plumose. Animal swims freely in the water.

152 BRITISH ENTOMOSTllACA.

1. CYPRIS TRISTRIATA. Tab. XVIII, figs. 1, 1 a-i ; 2, 3.

CYPRIS TRISTRIATA, Baird, Trans. Berw. Nat. Club, i, 99, t. 3, f. 13,

1835 ; and ii, 152.
Cyi'Ris PUBERA, Baird, Mag. Zool. aud Bot., i, 524, t. 1C, f. 1-13.

Shell of an oval form, and somewhat reniform ; the
valves convex, and of a green colour, more or less deep.
The anterior portion is of a deep green, immediately
behind which is a portion of a lighter colour ; the pos-
terior part is of a less deep green, and has three narrow
bands or streaks, two of which are of a much deeper hue,
running obliquely across it. The whole shell is covered
with dense, short hairs.

In some specimens, generally the largest, the shell is
of nearly a dirty black colour, from the dirt which adheres
to it obscuring the marks which distinguish the species.
Nearly in the centre of each valve is to be seen a congeries
of about seven small, lucid spots. The filaments of both
pairs of antennae are beautifully plumose.

Halt. — Berwickshire ; near London, &c. ; not un-
common, all the summer months.

2. CYPRIS VIDUA. Tab. XIX, figs. 10, 11.

CYPRIS VIDUA, Miillcr, Zool. Dan. Prod., No. 2384, 1776; Eutomos-

traca, 55, t. 4. f. 7-9.
Latreille, Hist. Nat. Crust,, iv, 245.
Bosc, Man. d'Hist. Nat, Crust., ii, 297.
Desmarest, 385, t. 55, f. I.
Baird, Mag. Zool. and Bot., i, 133, t. 5, f. 1 ; Trans.

Bcrw. Nat. Club, ii, 152.

M. I'jlin, ,-</*, Hist. Nat, Crust., iii, 399, t. 30, f. 4.
MIIXOCULUS VLDUUS, <.:,,trrni, Linn. Syst. Nat., 3002, No. 42.

M,i,/i'i'l, Euc. mrtli., vii, 726, No. 36, t. 264,

f. 24-26.

,1 urine, Hist. Nat. Monoc., 175, t, 19, f. 5, 6.
Ifn's, Cyclopaedia, art. Mouoculus.
MONOCULUS VIDUATUS, Fabricius, Ent. Syst., ii, 496.

Shell of an oval form, a little siimntrd on under margin,

CYPR1S. 153

and beset all round with dense, fine, short hairs. The
colour is a dull white, and the valves are distinctly marked
with three black, somewhat waved fascia?, running trans-
versely across the shell at unequal distances, the most an-
terior of the three being the smallest. Posterior margin
rather narrower than anterior.*

Halt. — Neighbourhood of London, Rugby, &c. &c. ;
common during the summer months.

3. CTPRIS MONACHA. Tab. XVIII, fig. 6.

CYPRIS MONACHA, Midler, Zool. Dan. Prod., No. 2390, 1776; Ento-
inostraca, 60, t. 5, f. 6-8.

— Latreille, Hist. Nat. Crust., iv, 247.

— Bosc, Man. d'Hist. Nat. Crust., ii, 297.

— Desmarest, Consid. gen. et part, des Crust., 384,

t. 55, f. 7.
Baird, Mag. Zool. andBot., i, 133, t. 5, f. 2 ; Trans.

Berw. Nat. Club, ii, 152.
If. Edwards, iii, 397.
Koch, Deutsch. Crustac., h. ii, t. 1.
MONOCULUS MONACHUS, Omelin, Linn. Syst. Nat., 3003, No. 44.

— Manuel, Enc. meth., vii, 727, No. 41, t. 266,

f. 34-36.

Fabricius, Ent. Syst., ii, 497.
Rees, Cyclopsed., art. Mouoc.
Jurine, Hist. Nat. Monoc., 173, 1. 18, f. 13, 14.
CYPRIS NUBILOSA (?), Koch, Deutsch. Crustac., h. xii, t. 4.

Shell of a rhomboidal form, rounded at posterior margin,
and truncated as it were anteriorly ; glabrous, with a few
hairs on posterior margin. The surface of the shell is re-
ticulated, or, as Miiller says, marked with small points
impressed into, or as it were excavated out of, the shell.
The upper part is nearly of a white colour, while the lower
portion of anterior margin, and part of posterior, are very
dark, shaded with a yellow green. The filaments of pos-
terior antennae are long.

A very pretty and well-marked species.

* It is not so narrow at the posterior extremity as is represented by
Juriiie. Muller's figure represents the anterior extremity as the narrower.

154 BRITISH ENTOMOSTRACA.

//^//.—Neighbourhood of London, July, August, and
September. Old canal at Rugby ; Ncwnliam Loch,
Northumberland, Dr. Johnston.

4. CYPRIS FUSCA. Tab. XIX, fig. 7.

CYPRIS ruscA, Sln/us, Mem. Mas. Hist. Nat., vii, t. 1, f. 16, 1821.

— Desmarest, Consid. gen. ct part. Crust., 384.

— M. MM f<l*} 1 1 iM . N at . Crust., iii, 401, t. 36, f. 3.
Baird, Mag. Zool. and Bot., i, 134, t. 5, f. 4; Ti;m>

Berw. Nat. Club, ii, 152.
Guei-in, Icouog. Regne An. Crust., t. 32, f. 4.

Shell oval, of a uniform brown colour, sinuated on
under margin. The anterior extremity is narrower than
the posterior, which is rounded and broad. The valves
are covered with fine hairs. Filaments of posterior an-
tenna' only three in number, and rather short.

. — Neighbourhood of London ; Hampstead, &c.,
June, July, and August.

5. CYPRIS COMPRESSA. Tab. XIX, figs. 14, 14 a-c.

CVPIUS COMPRESSA, Baird, Trans. Bcrw. Nat. Club, i, 100, t. 3, f. I ^.
1835, and ii, 152 ; Mag. Zool. and Bot., i, 13(1,
t. 5, f. 7.

— M. i;<ltr<t,-<l*} Hist. Nat. Crust., iii, 400.

CYPRIS PUNCTATA, A'oc//, Dcutsch. Crustae., h. xxi, t. 23, 183S.

(Not CYPRIS COMPKKSSA, Koch, 1. c. t. 17.)
( 'i i'i( is TI.NKI; \, AW/, I.e., Ii. xii, t. 3.

Shell of a rounded form, but compressed, narrower an-
teriorly than posteriorly, of a brownish-gray colour, more
or less deep, semi-transparent, beset at both extremities
with fine hairs. In general the surface of the shell is
-potted, as if from little pieces being hollowed out of its
substance. Eye large. Filaments of posterior antenna1,
three long and one short. From the thin, compressed
shape of the shell, the motion of the little animal through
the \\aler is\er\ inueli like that of some of the L\nceid;e.

CYPRIS. 155

Hah. — Yetholm Loch ; neighbourhood of London ;
Rugby, &c. ; common from May to January.

0. CYPRIS MINUTA. Tab. XVIII, figs. 7, 8.

Ci'PEis MINUTA, Baird, Trails. Berw. Nat. Club, i, 99, t. 3, f. 9, 1835,
and ii, 152 ; Mag. Zool. and Bot., i, 136, t. 5, f. 11.
M. Edwards, Hist. Nat. Crust., iii, 403.
MONOCULUS OVUM (?), Jurine, Hist. Nat. Monoc., 179, 1. 19, f. 18, 19.

Shell oval, broader posteriorly than anteriorly, elevated
and rounded on upper margin, slightly sinuated on under
edge, of a light-brown colour, with a tinge of green. The
valves are smooth and shining in the centre, and beset all
round with short hairs. This is the smallest of all the
species I have yet met with, and approaches very near to
Monoc. ovum of Jurine, except that he says his species is
perfectly smooth, whereas this is beset all round the shell
with fine hairs.

Hal). — Yetholm ; neighbourhood of London, &c.,
summer months.

7. CYPRIS JOANNA. Tab. XVIII, fig. 5.

CYPRIS JOANNA, Baird, Trails. Berw. Nat. Club, i, 99, t. 3, f. 8, 1835,
and ii, 152 ; Mag. Zool. and Bot., i, 136, t. 5, f. 12.
M. Edwards, Hist. Nat. Crust., iii, 403.

Shell rounded ovate, narrower anteriorly than pos-
teriorly, of a brown colour, with an orange mark across
the back of shell and the lower margin. Shell beset all
round with rigid hairs, and covered with minute black
points or dots. Approaches the C. pilosa of Miiller, but
is smaller, and is otherwise distinguished from it by the
orange mark across the back, and by not being glabrous,
but marked all over with black, roughish-looking points.
It is a little longer than C. minuta.

Had. — Pool of water on one of the Laminermuir hills,
near Abbey St. Bathans, Berwickshire, August 1835.

15G BRITISH ENTOMOSTRACA.

8. CYPRIS ELONGATA. Tab. XIX, fig. G.

C VPRIS ELONGATA, Baird, Trans. Bcrw. Nat . Club, i, 99, t. 3, f . 10, 1835,
and ii,152 ; Mag. Zool. and Bot., i,137, t. 5, f.13.
— M. Ethrards, Hist. Nat. Crust,, iii, -iO-1.

Shell wedge-shaped ; anterior extremity much broader
than posterior, which is narrow and much elongated. The
valves are elevated on the upper margin, towards the an-
terior extremity, and situated on the under edge ; they
are white, transparent, and hairy.

Hob. — At Yetholm, Roxburghshire, July 1835.

9. CYPRIS WESTWOODII. Tab. XIX, fig. 9.

CYPKIS WESTWOODII, Baird, Trans. Benv. Nat. Club, i, 99, t. 3, f. 12,

1835, and ii, 152; Mag. Zool. and Bot.,
i, 137, t. 5, f. 14.
M. Ed/wils, Hist. Nat. Crust., iii, -100.

Shell reniform, much elevated, and rounded on upper
margin, deeply sinuated underneath ; rather broader at
anterior extremity, of a green colour, and semi-transparent.
The valves arc covered all over with rather long hairs, and
the filaments of posterior antenna' are very long.

]Ial. — Yetholm Loch, Roxburghshire, July 1835.

10. CYPRIS GIBBOSA. Tab. XIX, fig. 8.

CYPRIS GIBBOSA, Baird, Mag. Zool. and Bot., i, 137, t. 5, f. 15, 1S37;

Trans. Bcrw. Nat. Club, ii, 152.
M. i'.di'-anla, Hist. Nat. Crust., iii, 401.

Shell ovate, and much elevated on the upper margin,
the centre exhibiting a large gil>bi»ii\ ur hmu|> ; sinuated
underneath. The \alves are smooth, except round the
edges, which are beset with short, tine hairs, are nearly
opaque, and of a light green colour, the anterior extremity
being paler than the other parts of the shell. Filaments
of both pairs of antenna- beautifully plumose.

Huh. — Ditch near the Surrey Zoological (Jardens, -June

CYPRIS. 157

11. CYPRIS CLAVATA. Tab. XVIII, fig. 4.

CYPRIS CLAYATA, liaird, Mag. Zool. aud Bot., i, 137, t. 5, f. 16, 1837;

Trans. Bcrw. Nat. Club, ii, 152.
M. Edwards, Hist. Nat. Crust., iii, 405.

Shell oblong, narrower at posterior extremity than
anterior, which is rather flattened, giving the shell the
appearance of being club-shaped. The valves have the
upper margin elevated, and the lower nearly straight.
They are smooth and shining, but beset round the margin
with short hairs ; their colour is of a light gray, with an
obscure dark-coloured ray running from the centre towards
the posterior extremity, which again is distinctly marked
with an orange-coloured spot.

The antennae and feet are short, compared with the size
of the shell. The filaments of both pairs of antennae are
plumose.

This species approaches near to C. crassa of Miiller, as
described by him ; but differs in toto from the figure
which he gives of it.

. — In a pond near Copenhagen Fields, July 1836.

12. CYPRIS STRIGATA.

CYPRIS STRIGATA, Miiller, Zool. Dan. Prod, 199, 2387, 1776;

Entomostraca, 54, t. 4, f. 4-6.

— Eamdohr, Beyt. zur Naturg, 14-17, t. 4, f. 1-14.

— Latreille, Hist. Nat. Crust., iv, 245.
Desmarest, Cons. gen. et part. Crust, 386.

— Base, Man. d'Hist. Nat. Crust, ii, 297.

— Baird, Trans. Berw. Nat. Club, i, 99, ii, 152 ;

Mag. Zool. and Bot, i, 132.

MONOCULUS STRIGATUS, Gmelin, Linn. Syst. Nat, 3002, 37.

Fabricius, Ent. Syst, ii, 496.

— Manuel, Euc. metli, vii, 726, No. 31.

— Rees, Cyclopaedia, art. Monoc.
MOXOCULTJS BISTRIGATTJS, /«n>e,Hist. Nat. Mon, 177, 1. 19, f.12, 13.

— M. Edwards, Hist. Nat. Crust, iii, 403.

" Shell subovate, glabrous ; ciliated at the margins, sub-
linear at the aperture ; valves rather convex, brown, with
three white fasciae, the posterior one lunated, the middle

158 BRITISH ENTOMOSTRACA.

oblique, and the anterior arched ; or it may be described,
valves white on dorsal margin, bound by a brown belt,
with two oblique brown spots in the disc." —MiHlcr.

Hub. — Pool on seashore, a little above high-water mark,
at Thornton Loch, East Lothian, June 1835.

13. CYPRIS ELLIPTICA. Tab. XIX, fig. 12.

CYPRIS ELLIPTICA, Baird, Trans. Berw. Nat. Club, ii, 152, 1846 ;
Ann. and Mag. Nat. Hist., xvii, 111, t, 9, f. 12.

Shell nearly elliptical, of a light green colour, clouded
with darker patches of the same colour on the sides of the
shell. Valves glabrous, except round the edges, which
are beset with short hairs. Filaments of posterior an-
tennae long.

I lab.— Pond at Highgate ; July 1846.

14. CYPRIS SELLA. Tab. XIX, figs. 5, 5 a.

CYPRIS SELLA, Baird, Trans. Bcrw. Nat. Club, ii, 152, 1846; Ann.
and Mag. Nat. His!., xvii, 114, t. 9, f. .'5.

Shell ovate globose, of a uniform light green colour,
marked on the back and side with a patch of a darker hue.
A dark streak runs along the upper edge of the shell, be-
ginning from immediately behind the eye, and terminating
at about the same distance from the posterior extremity.
It then extends a short way down the side, and then rim^

\l

forward a little way in a somewhat lunated shape. At
the anterior commencement of the dorsal mark a narrower
streak of the same colour runs down the side, stopping
only a short distance from the anterior margin. The
shell is densely beset all round with short hairs.

This specie's resembles a little the ('///iri* riifita in shape,
but is smaller, and ditlers very considerably in the mark-
ings, which are uniformly the same.

llnli.— Pond on Clapham Common, July 1M(>.

CANDONA. 159

15. CYPRIS AURANTIA. Tab. XIX, fig. 13.

MONOCULUS AURANTIUS, Jurim, Hist. Mouoc., 173, t. 18, f. 5-12.
CYPKIS AURANTIA, Desmarest, Cons. gen. Crust., 3S4.

M. Edwards, Hist. Nat. Crust., iii, 402.

Shell oval, rounded on dorsal margin, slightly sinuated
on ventral margin ; beset all round with short hairs.
Anterior extremity rather narrower than posterior. The
shell is of a finely polished appearance, and of an orange
colour. On the posterior half it is marked with a rather
broad band of a lighter hue, running obliquely across ; the
darker portions of the shell, on each side of it, terminating
abruptly in a marked line of a deeper colour than the
general shade of the rest of the shell.

Hab. — Blackheath, June. Windsor Great Park, July.
Dover, September 1849.

Genus 2 — CANDONA.

Character, — Externally resembling Cypris ; but the in-
ferior or pediform antennae are destitute of the pencil of
long hairs which characterise that genus. The animal
creeps at the bottom or upon aquatic plants, instead of
swimming freely through the water.

The genus Cypris, as established by Miiller, had, up to
1845, remained intact. As, however, a number of the
species which have been described possess a set of organs
which many others do not, and which exercise a decided
influence upon their economy and habits, I thought it be-
came incumbent to separate the two sets of species into
distinct genera. In the one series the animals have a much
greater degree of motion and agility than the others, swim-
ming freely and rapidly through the water in all directions,
and apparently possessing a higher degree of enjoyment
in their existence. This arises from the bundle of long
plumose setas which spring from the second articulation of
the posterior or pediform antennae described above (p.
145), and by means of which they can suspend themselves
in the water, or transport themselves through it with
great facility. For this set I have retained the name of

160 BRITISH ENTOMOSTRACA.

Cypris. Tlie others are deficient in this apparatus, and
instead of swimming gaily through the limpid element,
crawl in the mud at the bottom of the pools in which they
are found, or creep along the aquatic plants which grow
there, and if dropped into a glass of water, fall to the
bottom, without being able to suspend themselves for the
shortest time. These constitute the genus Candona, which
I first published in the ' Trans. Bervv. Nat. Club,' ii, p.
152, 1845, and afterwards in the ' Ann. and Mag. Nat.
Hist./ xvii, p. 414.*

1. CANDONA LUCENS. Tab. XIX, fig. 1.

CTPRIS LUCENS, Baird, Trans. Bcnv. Nat. Club, i, 100, t. 3, f. 15, 1835.
CYFKIS CANDIDA, Baird, Mag. Zool. and Bot., ii, 131-, t. 5, f. 3.
CANDONA CANDIDA, Baird, Trans. Bonv. Nat. Club, ii. 353, 18-15.
CYPRIS PELLUCIDA, Koch, Deutsch. Crust., h. xi, t. 5, 1837.
CYPRIS LTJCIDA (?), Koch, Deutsch. Crust., h. xxi, t. 18, 1838.

Shell somewhat reniform, arched on the upper margin,
and sinuated underneath. The valves are ventricose in
the middle, smooth, except round the edges, which are
fringed with fine short hairs, shining, of a pure white
colour, with a pearly lustre, and nearly opaque. The
anterior extremity is narrower and flatter than the pos-
terior, which is prominently arched on the upper angle,
and prolonged interiorly to a short point.

I lab. - - Neighbourhood of London, Cockburnspath,
Yetholm, &c. ; summer and autumn months.

:2. CANDONA RKPTANS. Tab. XIX, figs. 3, 3«.

Cvi'Kis I;I;ITANS, />V//v/, Trans. Berw. Nat. Club, i, 99, t. 3, f. 11,1s:!;, ;

Ma- ZOOL and I'.ot., ii, l.Vi, t.5, f. 5.
.I/. l-:,/ir,i,-'lx, Hist. Nat. Crust., iii, -100.
CANDONA REFTANS, ./>',»',•>/, Trans. Bmv. Nat. Club, ii, 153, IS I.").

Shell ovate elliptical, nearly plane on upper margin,
and slightly sinuated underneath. The valves arc rather

* For further characters of tliis irmus, srr thr (Wiiir < nhM

ofllir ' Kntumostrara c.l' I lie Cretaceous Formation of England,' by T.
Jones, Esq., publishing l>v ilic Patoontotrrajiliical Snciri\.

CANDONA. 161

prominent or gibbous in the centre, and glabrous, the
edges being fringed with rather long hairs. The colour
is of a light whitish-green, variegated with marks on the
anterior and posterior margins ; and on the sides, of the
same colour, but of a deeper hue.

Hab. — Neighbourhood of London, summer months.
Yetholm Loch ; Newnham Loch, Northumberland, Dr.
Johnston.

3. CANDONA HISPIDA. Tab. XIX, fig. 4.

CYPRIS HISPIDA, Baird, Trans. Berw. Nat. Club, i, 99, t. 3, f. 14, 1835 ;

Mag. Zool. and Bot., ii, 135, t. 5, f. 6.
M. Edwards, Hist. Nat. Crust., iii, 405.
CANDONA HISPIDA, Baird, Traus. Berw. Nat. Club, ii, 153, 1845.

Shell oval, rather ventricose, the anterior extremity a
little broader than the posterior. The colour is a uniform
brown, with one or two marks of a deeper hue running
across the centre ; both extremities partaking of the same
dark shade. The valves are very hispid, their surface
being covered with spines rather than hairs.

Hab. — Neighbourhood of London ; Yetholm. Summer
months.

4.- CANDONA DETECTA.

CYPRIS DETECTA, Midler, Zool. Dan. Prod., No. 2386, 1776 ; Euto-

mostraca, 49, t. 3, f. 1-3.
Bosc, Man. d'Hist. Nat. Crust., ii, 295.
Latreille, Hist. Nat. Crust., iv, 211.
Leach, Edinb. Encyc. art. Crust., vii, 388.
Baird, Mag. Zool. and Bot., i, 525.
Lamarck, Hist. An. s. Vert., v, 124.
MONOCULUS DETECTUS, Gmelin, Linn. Syst. Nat., 3001, No. 36.

Manuel, Euc. muth., vii, 725, No. 30, t. 266,

f. 15-17.

Sees, Eucyclop., art. Mouoculus.

SMOOTH WHITE INSECT, Mutter, Phil. Trans,, Ixi, 230, t. 7, f. 1-3.
CANDONA DETECTA, Baird, Trans. Berw. Nat. Club, ii, 153, 1S45.

Shell oblong oval; the anterior extremity rather narrower

11

16:2 BRITISH ENTOMOSTRACA.

than posterior, upper margin slightly arched, ;nid inferior
edge somewhat sinuated. The valves are flatter than in
almost any other speeies, pellucid, and quite smooth.
The colour is of a dull white, without any spots or marks.
The (.'. (fi'/ccfa of Miiller is quite a different species from
the j\fonoc. conchaceus of Jurinc, though that author
quotes them as synonymous, in which, though with hesita-
tion, he is followed by M. Edwards. These synonyms,
therefore, as quoted by me in the ' Mag. Zool. and Bot.,'
must be expunged.

Hal). — Neighbourhood of London ; Pool on Beaumont
Water, &c. ; not common.

5. CANDONA SIMILIS. Tab. XIX, figs. 2,

CANDONA SIMILIS, Baird, Trans. Bcrw. Nat. Club, ii, 153, 18-i5; Ami.
and Mag. Nat, Hist., xvii, 415, t, '.), f. I.

Shell somewhat elliptical in figure, flat, slightly sinu-
ated in the middle of the lower margin, and nearly plain
on dorsal edge. The colour is white, with two dark-
orange spots on the back. The valves arc smooth, except
round the edges, which are fringed with rather stiff hairs ;
these are more numerous on anterior extremity than on
posterior. The shell is narrower posteriorly than ante-
riorly, and is transparent. Its motion is very deliberate,
when it walks along the plants, first putting one foot for-
ward, and then leisurely drawing up the other. It ap-
proaches near to the ( '. i/c/ccfa of Midler ; the posterior
extremity, however, is narrower than anterior, which is
the reverse in the

Huh. — Pond on Clapham Common, July 1S4G.

11—
( vi m.iUNEN, Kwmcf, Jahrbucli, 1838.

/•.- -Two pairs of antenna";; superior not fur-
nished with the pencil of long filaments. Feet, three pairs.

This family eoniains 1 wo British genera — (
and CYTIII 1:1 [8

CYTHERK. 163

Genus 1 — CYTHERE.

CYTHEKE, Mi'dler, Latreille, Desmurest, M. Edwards, Sfc. $-c.
CYTHERINA, Lamarck, Sowerby, Munstcr, Roemer, 8fc. 8fc.
CYPRIDINA, Bosquet (not M. Edwards).
BAIRDIA, M'Coy, Jones*

Character. — One eye. Three pairs of feet; all ex-
ternal, none being inclosed within the shell. Abdomen
short. Inferior or pediform antennae furnished with one
tolerably long, curved and jointed filament. Superior
antennae simple, setiferous, and not provided with any
pencil of long filaments.

Bibliographical History. — Before Miiller's time the
animals of this genus were perfectly unknown, not the
slightest mention of their existence having been made by
any previous writer. As he is the first who has noticed
them, so he is the only author to whom we can refer for
any information respecting them, with the exception of
what I have added in my paper in the ' Mag. of Zool.
and Botany' for August 1837. Upon a slight inspection
the Cytheres might be mistaken for Cyprides ; but their
superior antennae,, being simple and free from the pencil
of long hairs with which these organs in the Cypris are
endowed, their possessing three pairs of feet, all of which
project out of the shell, and the want of the long tail or
abdomen, sufficiently distinguish the two genera. It is in
his ' Entomostraca' that Miiller first established the genus,
and the above marks of distinction between it and the
Cypris constitute almost all the knowledge that he imparts
to us concerning it. Meagre as it is in its details, it has
not been enlarged by any succeeding author.

Gmelin, in the 'Syst. Nat.,' 1788, Eabricius, in his
'Ent. Syst.,' 1793, Manuel, in the 'Encyc. meth.,' 1792,
Latreille, in his 'Hist. Nat. Crust, et Ins./ 1802, either

* The animal, in those recent species which have been referred by Mr. Jones
to the sub-genus BAIRDIA, M'Coy, and which I have had an opportunity of
examining, does not differ in the least from the animal of the Cythere proper.

1 li I HHITTSII EXTOMOSTI! \( A

merely give the species alone, or repeat the few remarks
made by M filler, without making any comment or original
observations of their own. Lamarck, in his 'Anim.
s. Vert./ 1818, changes M filler's name, ami gives the
genus the appellation of Cytheriiui, while Dcsmarest, in
his 'Cons, sur Crust./ 182 5, in repeating the observa-
tions made by Miillcr, and giving merely his species, adds,
that it may turn out that some of the feet may be par-
ticular organs, and that the number may be found to be
the same as in the Cypris, — a conjecture which Latreille
also makes in the last edition of Cuvier's * Rcgne Anim.,
1829. Desmarest moreover says, "reasoning from ana-
logy, we are led to believe that the Cytherc, like the
Cypris, has branchial plates attached to the mandibles and
jaws, and that their feet are solely destined for locomo-
tion." *

Anatomy and Physiology t$c.— The shell in almost every
respect strictly resembles that of the Cypris; but from
its general opacity and minuteness it is exceedingly
difficult to examine with precision the body of the
inclosed animal. After repeated attempts, however, to
break down the horny opaque shell I succeeded so far as
to discover that, like the Cypris, the body is di\ided into
two parts connected with each other by a narrow space ; the
anterior or thoracic portion containing the eye, the supe-
rior and inferior antenna*, organs of mouth, and two pairs
of feet; the posterior or abdominal portion, containing
the third pair of feet, and a short appendix or tail.

The eye resembles in appearance and situation that of
the Cypris, being single, fixed, and in form of a black
sessile point.

The superior antenna- (t. \\: f. 5 /;) are composed
each of seven joints, furnished with one or two short
setae at the base of each of the four last articulations,
;md terminated by several rather longer hairs at the

• i ons •-••' n <•' part., &c , p '-'^1 •

CYTHERK. 165

extremity of the last joint, differing materially in this
respect from the same organs in the Cypris. The inferior
antennae (t. XX, f. 5<?) are inserted immediately beneath
these, and are by far the stronger of the two. They differ
considerably in shape from the superior ones, being
flatter, falcated in appearance, and as in the Cypris and
Candona, more like feet than antennae. They consist of
five articulations ; the first and third being very short.
The last gives off on internal edge, three spines, and is
terminated by a tuft of stout setae, as in the Candona,
while from the base of the second joint there springs a
long, stiff seta, equalling in length the last two joints,
and being divided into three articulations, of which the
middle is the longest. This seta is mentioned by Miiller
as occurring in the Cytkere luiea, and is taken notice of
by him as being peculiar to it, or at best as not having
been seen in any other species. It occurs, however, in all
that I have examined, and seems to take the place of the
pencil of long hairs that is to be found on the penultimate
joint of the corresponding organs in the genus Cypris,
but the precise use of which I do not understand. These
organs are, as in the Cypris and Candona, directed back-
wards.

The feet (t. XX, f.4«/, 5/) are three pairs in number, and
are all exactly like each other, except in length. They
are round and slender, and consist each of five articula-
tions, the second of which is the largest, and gives off a
short spine from its base. The last is the shortest, and
is terminated by one or two long, curved hooks,, or strong
setae. They are all directed forwards. The first of these
three pairs is very short ; the second a little longer ;
whilst the third, or last pair, is the longest of all, being
longer than the inferior antennae, though much more
slender. This last or posterior pair (f. 5/) appears to arise
from near the junction of the two halves of the body, and
may supply, as Miiller says, the want of the tail.

The mouth is situated in the inferior surface of the an-
terior half of the body, as in the Cypris, and appears to

166 BRITISH ENTOMOSTKACA.

consist of exactly the same organs as in the animals of that
genus, though, from their extreme minuteness and want
of lengthened opportunities for examination, I have not
been able to make out all the parts. The palpifcrous
mandibles, and the first pair of jaws with their branchial
plates, arc the only parts I have clearly distinguished,
and they resemble in almost every respect the correspond-
ing organs of the Cyprides.

The mandible (t. XX, f. 5c) is formed of two pieces -. the
larger of the two, or proper mandible, as in the Cypris,
being terminated at the superior extremity by a sharp
point, and at the lower or incisive extremity by about six
or eight pretty strong teeth ; while the other part, the
palpus, consists of three or four joints, plentifully supplied
at the extremities of the articulations with numerous seta?,
and a small branchial plate of one joint attached to the
first articulation. The first pair of jaw^s (t. XX, f. 5 d], as
in the Cypris, consists also of tw^o parts, the square plate,
with the four fingers, the superior of which has two joints,
while the others have only one, and are all terminated by
a tuft of seta? ; and the branchial plate attached, of an
elongated oval form, furnished with fourteen long setae,
which are given off from both sides. As these organs arc-
so very similar to the corresponding organs in the (Vpris.
1 have no doubt that the other parts (the lips and second
pair of jaws) ;ire also alike, and therefore that the suppo-
sition of Desmarest, with respect to some of the inter-
mediate feet being peculiar organs, is incorrect, and that
as their use and situation indicate, they are all true feet,
and used solely for locomotion, the posterior pair perhaps
serving, in addition, one of the uses of the tail of llie
Cypris, that of cleaning the inside of the shell, for which
they are well adapted, from their length and the great
degree of mobility they possess.

The appendix, or short tail, is of such an irregular
figure, that until belter opportunities occur for examina-
tion, I >hall no! attempt a minute description. The in-
(<Tiial anatomy I have not succeeded in making out at all.

CYTHERE. 167

neither have I ever seen any individual with ova, though
this may perhaps be accounted for, from the specimens
which I have examined being chiefly dissected in the
winter months.

These little creatures are chiefly to be found in sea-
water, and may be met with in all the little pools among
the rocks on the seashore. They live among the Fuci and
Confervse, &c., which are to be found in such pools ; and
the naturalist may especially find them in abundance in
those beautiful, clear, little, round wells which are so
frequently to be met with, hollowed out of the rocks of
the seashore, which are within reach of the tide, and the
water of which is kept sweet and wholesome, by being
thus changed twice during every twenty-four hours. In
such delightful pools, clear as crystal, when left undis-
turbed by the receding tide, these interesting animals may
be found, often in great numbers, sporting about amongst
the Confervse and Corallines, which so elegantly and fanci-
fully fringe their edges and decorate their sides, and
which form such a glorious subaqueous forest for myriads
of living creatures to disport themselves in. Sheltered
amongst the "umbrageous multitude" of stems and
branches, and nestling in security in their forest glades,
they are safe from the ravages of the advancing tide, though
lashed up to fury by the opposing rocks which for a
moment check its advance; and weak and powerless though
such pigmies seem to be, they are yet found as numerous
and active in their little wells, after the shores have been
desolated by the mighty force of the tide, which has been
driven in in thunder by the power of a fierce tempest, as
when the waves have rolled gently and calmly to the shore
in their sweetest murmurs. Hitherto they have been
found very sparingly in fresh water, two species only
having been noticed.

These animals have never been seen to swim, invariably
walking among the branches or leaves of the Confervse or
Euci, &c., where they delight to dwell. When shook out
from their hiding-places into a bottle or tumbler of water,

168 BRITISH ENTOMOSTHACA.

they may be seen to fall in gyrations to the bottom, with-
out ever attempting to dart through the watery element,
as is the case with the Cy prides. Upon reaching the
bottom, they open their shells and creep along the surface
of the glass ; but when touched or shook, they immediately
again withdraw themselves within their shell, and remain
motionless. This inability to swim is no doubt owing
to the want of the pencils of long hairs or filaments which
adorn the superior and inferior antennic- of the Cypriotes,
and which we have already seen are the organs "by means
of which they swim. My opportunities for observing
these tiny animals have been so limited, and the difficulty
of keeping them alive, from the rapidity with wliidi sea-
water becomes putrid when kept in a room in a small
vessel, is so great, that I cannot make any additional
statements respecting their economy or habits. The
species, however, are undoubtedly numerous, and the
labours of any inquirer after them would assuredly be
rewarded with much success.

1. CYiiiKKE FLAVIDA. Tab. XXI, figs. 12, 12 a.

CVTHEUE TLAVIDA, Mi'lli'f, Kllt.oiliost ., '•('), t. 7, f. 5, 6, 17S1.

Ltifmllf, Hist. Nat, Crust., iv, 253.
Des»/a/-cxf, Consul, gen. ct part. Crust., 3s v
Bosc, Man. d'Hist. Nat. Crust., ii, 2s I.
Baifl, Mag. Zool. and Bot., ii, 112; Tran.-.

Berw. Nat. Club, ii, 153.
MONOCULUS FLAVIDUS, (luiflhi, Linn. S\s1. Nat., 3001, No. 33.

Fit/H-icittx, Ent. Syst., ii, 49-1.

Manuel, Kuc. m&h., vii, 725, t. 200, f. 10, 11.

Rccs, Cyclojunl. art. Mouoculus.

Shell oblong, narrow, anterior extremity more acute
than posterior; smooth, shining, of a pale u-llmv horn
colour, and transparent. Inferior margin nearly straight;
superior arched.

Unit. — Among Conferva; in pools of sea-water at Cocks-
bimispiitli, Berwickshire, 1885. In sand, from Torquay ;
W '. ('. \Villiamson, Es(j.

CYTHERE. 109

2. CYTHERE RENIFORMIS. Tab. XX, figs. 5, 5 a-f.

Cv Til ERE RENIFORMIS, Baird, Trans. Bcrw. Nat. Club, i, 98, t. 3,

f. 5, 1835 ; and ii, 153 ; Mag. Zool. and
Bot., ii, 142, t. 5, f. 16-22.
M. Edwards, Hist. Nat. Crust., iii, 408.

Shell reniform, rough with hairs ; both extremities of
nearly equal size, anterior a little flatter than posterior.
The centre of the valves is covered with a calcareous-
looking crust, which is rather of a darker colour than the
rest of the shell, and appears studded all over with short
spines. The colour of the shell is of a light brownish
yellow ; and the legs and antennae of the animal are
brightly marked with the same hue.

It approaches the C. lutea, Mull., in shape ; but differs
somewhat in colour, in being roughly hairy, and having
the valves covered with the hard crust.

Hab. — Coast of Berwickshire ; at Cockburnspath, Ber-
wick, &c., 1835. N. Foreland, near Dover, August and
September, 1849.

3. CYTHERE ALBO-MACULATA. Tab. XX, fig. 7.

CYTHERE ALBO-MACULATA, Baird, Mag. Zool. and Bot., ii, 142, t. 5,

f. 23, 1838 ; Trans. Berw. Nat. Club, ii, 153.
M. Edwards, Hist. Nat. Crust., iii, 408.

Shell oblong, a little flatter at the anterior extremity,
gently rounded on the upper margin, and deeply sinuated
on the lower, near the anterior extremity. Both the ex-
tremities and the lower margin are densely hairy. The
central portion of the valves is covered with a calcareous-
looking crust, as in the last species, and is studded all
over with short spines, except where it is marked with two
white, smooth, shining spots of considerable size. The
colour of the shell is altogether of a dull brown.

Hab. — Berwick Bay, 1835 ; not very common ; near
Dover, September 1849.

170 BRITISH ENTOMOSTRACA.

4. CYTHERE ALBA. Tab. XX, fig. 6.

CVTHERE ALBA, Baird, Trans. Berw. Nat. Chib, i, 98, t. 3, f. 6,1835,
and ii, 153 ; Mas*. Zool. and Bot., ii, 1-43, t. 5, f. 21.
— M. Edwards, Hist. Nat. Crust., iii, 409.

Shell obovate, the anterior extremity much broader
than the posterior, fringed round the edges with short
hairs. The colour is white, and a margin extends all
round the outer edge still whiter than the body of the
shell. The valves are transparent, showing the dark body
of the insect shining through.

Had. — Sea-shore at Dunbar, East Lothian, 1835.
"). CYTHERE VARIABILIS. Tab. XXI, figs. 10, 11.

CYTHEB.E VAUIABILIS, Baird, Trans. Benv. Nat. Club, i, 98, t. 3,

f. 7, a, b, 1835, and ii, 153, ; Mag. Zool.
and Bot., ii, 143, t. 5, f. 25, a, b.
M. Edwards, Hist. Nat. Crust., iii, 409.

Shell oval, the anterior extremity considerably narrower
than the posterior, glaucous, without hairs. This species
varies much in colour and markings ; some individuals are
white, with two black fascia:1 running transversely across
the shell, one at the posterior margin, the other across the
centre of the valves, while the posterior extremity is marked
besides by a beautiful reddish or bright bron/e spot.
Others are of a light flesh colour, with the edges of the
shell slightly greenish, and the central portion marked
with dark streaks running across. Some again are alto-
gether of a fine flesh colour, without any marks upon the
valves, while others are of a uniform dark brown or almost
black hue. All these varieties, however, agree in shape
size, &c.

Hal). — Coast of Berwickshire ; common ; Dover, Sept.
L849.

CYTHERE. 171

b'. CYTHERE AURANTIA. Tab. XXI, fig. 8.

CYTIIERE AURANTIA, Baird, Mag. Zool. and Bot., ii, 143, t. 5, f. 26,

1835 ; Trans. Berw. Nat. Club, ii, 153.
M. Edwards, Hist. Nat. Crust., iii, 408.

Shell somewhat reniform, rounded and rather promi-
nent on upper margin ; slightly sinuated underneath, the
posterior extremity rather broader than the anterior. The
valves are smooth, glaucous, and of a bright orange colour.
This species is very minute.

Hob.— Berwick Bay; 1835.

7. CYTHERE NIGRESCENS. Tab. XXI, figs. 4, 4«.

CYTHERE NIGRESCENS, Baird, Mag. Zool. aiid Bot., ii. 143, t. 5, f. 27,

1838 ; Trans. Berw. Nat. Club, ii, 153.
— M, Edwards, Hist. Nat. Crust., iii, 409.

Shell gibbosely ovate, anterior extremity rounded, nar-
rower than posterior, which is marked by a gibbous pro-
jection above and below, and is terminated by a sharp
point. The valves are quite smooth and free from hairs,
of a dirty, black colour, and translucent, showing the
body of the animal, which is of a very dark hue, shining
through.

Hob. — Berwick Bay; not uncommon; 1835. Dover,
September 1849. Arran, Boston, &c., in sand; W. C.
Williamson, Esq.

8. CYTHERE MINNA. Tab. XX, figs. 4, 4 a-d.

BAIRBIA SILIQUA (var. c. ?), T. R. Jones, Eutomost. of the Cretaceous

Formation of England.

Shell elongate ovate, bluntly conical on the dorsal mar-
gin, nearly plain beneath ; obtusely rounded on anterior
extremity ; sharply acute posteriorly, and narrow, the ex-
tremity of the shell being produced into an acute point.
The valves are smooth, glabrous, white, and pellucid.
This is totally different from any yet described, and is a
/ery distinct species ; it is the largest of all I have seen.

\

172 BRITISH ENTOMOSTRACA.

Dredged in from eighty to ninety fathoms of
sand ; twenty miles east of the Noss in the Shetland Isles ;
R. M'Andrew, Esq.

9. CYTHERE INOPINATA. Tab. XX, figs. 1, 1 a-e.

CYTHEKE IXOPINATA, Baird, Zoologist/i, 195, f. a, b ; Trails. Bcrw.

Nat. Club, ii, 153.

Shell oblong ovate, nearly of equal size at each ex-
tremity ; white, with a slightly orange-coloured mark on
the upper edge; transparent, smooth, and shining ; perfectly
free from hairs, but possessing a few short, spinous pro-
jections on the lower margin of the posterior extremity.
Each valve has a gibbous projection about the middle,
which is best seen when the animal is lying on its back,
and is sinuated on the interior margin.

The superior antennae (f. 1 b] are composed of five (?) ar-
ticulations, and furnished with several rather short seta'.
The inferior or pediform antennas (f. 1 c) are provided with
a stout, jointed seta. This species is very small, and from
this circumstance and its always creeping at the bottom,
is easily overlooked.

This is the second species only that has as yet been
found inhabiting fresh water, Mr. Say having previously
described one as occurring in Georgia and Mast Florida.
See ' Journ. Acad. Nat. Sc./ Philad. 1817.

Hab. — The only place I have ever found this species is
in a small pond between llanwell and Soiithall, Middlesex.

10. CYTI-IEUE AN GUST AT A. Tab. XXI, fig. 6.

CYTHEKINA AM.ISTATA, Minister, Julirlmch i'iir Miiirralogie, 1838,

t.G, f. 10.

Shell oval oblong, obtuse at cither extremity, narrower
anteriorly, and slightly sinuated on inferior margin. It
is of a pale yellow colour, and the surface is shining and
polished-looking, but when examined by the microscope,
it is si-i-n to be eo\ered with small asperities The suit-
stance of the shell is lionn -looking and transparent.
Alou<: the ddi-sa! margin, on each side, there is a -cries of

CYTHERE. 173

indentations visible, which give it a kind of wrinkled ap-
pearance at that part.

Hab. — Devonshire, VV. C. Williamson, Esq.* Tenby,
T. Rupert Jones, Esq.

11. CYTHERE ACUTA. Tab. XXI, fig. 5.

Shell oval, convex, acute at both extremities, which are
nearly of equal size, of a pale, horny hue, smooth, glaucous,
transparent ; upper margin considerably arched and
rounded, the inferior one slightly so. In shape it some-
what resembles a grain of oats.

Hab. — Arran, in sand ; W. C, Williamson, Esq.

12. CYTHERE PELLUCID A. Tab. XXI, fig. 7.

Shell oblong, reniform, narrow; both extremities rounded
and nearly of the same size with each other ; pellucid, and
of a white colour. The surface at first appears smooth
and shining, but when examined with the microscope it
is seen to be minutely dotted or punctated.

Hab. — Boston, in sand ; W. C. Williamson, Esq.

13. CYTHERE IMPRESSA. Tab. XXI, fig. 9.

Shell oval, very convex, of much the same size at both
extremities. The surface of the shell is covered with im-
pressed punctations, and the colour is of a dull blackish
hue. The substance is of considerable thickness.

Hab. — Torquay, in sand ; W. C. Williamson, Esq.

14. CYTHERE QUADRIDENTATA. Tab. XXI, fig. 2.

Shell oval oblong, narrower at one extremity than the
other ; the longer extremity (the posterior) rounded and
slightly crenulated or toothed ; the narrower extremity
(anterior) produced and terminating in four distinct

* I am glad of this opportunity of acknowledging the kind and liberal
manner in which Mr. Williamson has placed his specimens of Ostracoda in
my hands for description.

1 ? I BRITISH ENTOMOSTRACA.

prominent teeth. The shell is white, and the surface is
grooved longitudinally, the grooves being marked with
rows of impressed punctures.

Approaches near CYTHEBJNA SCROBICULATA ofMunster,
\ideltoemer's ' Cytherinen,' &c., in Jahrbuch f iir Mineral.,
1838, t, 6, f. 1. '

I fab. — Along witli numerous specimens of C. niyrescens,
marked as coming from Boston, Torquay, and Arran, one
single specimen of this pretty species was sent to me by
\V. C. Williamson, Esq.

15. CYTHERE CONVEXA. Tab. XXI, fig. 3.

Shell rounded, very convex, and presenting very much
the appearance of a small Cypraea, or Cowrie shell. The
surface is covered with numerous small, white, raised dots
or points, which are disposed in radiating rows round the
circumference, and the whole shell is of a white colour,
and translucid. The margin of the shell is somewhat
waved.

Hab. — Torquay, in sand; W. C. Williamson, Esq.
Tenby, in sand, T. R. Jones, Esq.

Genus 2 — CYTIIEREIS.

( YniEREis, T. R. Jones, Entomost. of Crctac. Format .. I M'1
CYTHERE, Minister, Jahrlmrh i'iir Mineralogie: 1s."-1'

Cornwl, Mi'ni. Gcol. Soc. France.
CVTHERIXA, Roemer, Jahrbuch, &c., 1S3S.

/.'. HSS, Verstein. Hulim. Kividrfonn.
— //"////,////.•.•',„, Transact, Manch. Lit. Sor.
CYH;II>IN \, i;<..^ii'i'f, Mt'ni. Soc. Roy. Liege, 1817.

Animal unknown. Carapace valves or shell of an
almost regular oblong shape, the dorsal and \entral mar-
gins lying nearly parallel to each other. Surface of a
\ery irregular appearance, being wrinkled, ridged, and
lux-! with tuberchs, and crenulated or si rough toothed
on the margins.

CYTHEREIS. 175

1. CYTHEREIS WHITEII. Tab. XX, figs. 3, 3 a*

Shell oblong, flat, thin, somewhat narrower at one end
than at the other. Larger extremity rounded ; the nar-
rower extremity somewhat truncated and strongly toothed.
The anterior margin and rounded extremity are crenulated
throughout the whole of their length, and have placed
above them a sort of shelf or pinched-up fold, which runs
parallel with the margin, and which is strongly serrated. A
sharp crest, which is crenulated, runs along the centre of the
valve. The posterior margin is nearly straight and smooth.

This species is remarkably handsome, and approaches
near the Cypridlna serndata of Bosquet (Entomost. de
la Craie de Maestricht, t. iv, f. 2, a, d], but is distin-
guished from it by being shorter and broader, and by the
margin being continued straight to the end, and not in-
terrupted and toothed, as in that species.

Hab. — Torquay, in sand ; W. C. Williamson, Esq.
Tenby, in sand ; T. Rupert Jones, Esq.

2. CYTHEREIS JONESII. Tab. XX, fig. l.f

Shell thick, oblong oval, rather broader at one extre-
mity ; the narrower end flattened, with seven strong teeth
projecting from the edge, the outer teeth on each side
being the strongest ; the broader extremity rounded and
convex. The centre of the shell is plane and smooth, and
round the whole circumference there is a raised border or
narrow plate, which is perforated at frequent intervals by
open loop-holes.

This species approaches the Cytlierina coronata of
Roemer (vide Jahrbuch, 1833, t. vi, f. 30) in structure,
but differs totally in form, and in having the strong teeth
at narrow extremity.

Hab. — Isle of Skye, in sand ; W. C. Williamson, Esq.

* Named after Adam White, Esq., of the British Museum, well known
as the able describer of many new species of Crustacea.

f Named after T. Rupert Jones, Esq., author of the ' Entomostraca of
the Cretaceous Formation,' whose attention in forwarding me specimens of
Ostracoda for examination I thus gladly acknowledge.

170 BRITISH ENTOMOSTRACA.

3. CYTHEREIS ANTIQUATA. Tab. XX, fig. '2.

Shell oblong, very thick, rough with granulations, and
having two or three thick crests or ribs running along tin-
centre of the valves. One extremity is flattened, and has
four short, stout teeth springing from its edge ; the other
is more convex and rounded. The whole circumference
is wrinkled, and the shell presents a very antiquated
appearance.

Jlab. — Isle of Skye, in sand ; W. C. Williamson, Esq.

Family 2— CYPRIDINADJS.

Character. — Eyes two, pcdunculated. Antennae, two
pairs, both peditbrm. Eect two pairs ; one pair always
inclosed within the shell, and of a very peculiar structure.
Abdomen terminated by a broad lamellar plate, armed
with strong claws and hooked spines.

Genus CYPRIDINA.

CYPRIDINA, M. Edwards, Lamarck, Hist. Nat. An. s. "Vert., 2d edit.,

v, 178, note, 1838 ; Hist. Nat. Crust,, iii, 409.
Baird, Ann. and Mag. Nat. Hist., 2d scries, i, 21.
Dana, Conspcct. Crust., 50.
CYPRELLA (not CYPRIDINA), Bosquet, Eutomost. de la Craio dc

Maestricht.
ASTEROPE, PMlippi, Ann. Mag. Nat. Hist, (fide Dana in litcris.)

As there is but one genus, the character given above
for the family will suffice for it also.

The genus Cypridina was founded by M. IMwards in
1838, in a note to the genus Cypris, in the fifth volume
of Lamarck's 'Hist. Nat. An. s. Verteb.,' and was after-
wards more fully detailed in the third volume of his ' Hist.
Nat. Crust.' The animal resembles a good deal in its
general form ami structure that of the Gypris, while the
shell at first sight might easily he mistaken for one of that
uciuis. It has, however, two eyes, distinct from each
other; t\\o pairs of autenn;e, both peditbrm ; one pair of
natatory feet ; and a peculiar organ, apparently for sup-
porting the o\a, similar in purpose to, but differing in

OYPRir>TNA. 177

structure from, the second pair of feet in the Cypris.
Only one species has been described by M. Edwards, a
native of the Indian Ocean ; but in the ' Ann. and Mag.
of Nat. Hist.' for December 1847, I described two addi-
tional, one of which is a native of the Atlantic Ocean, and
the other an inhabitant of the Scottish seas.

Anatomy, 8fc. — The eyes are two in number, situated
nearly in the middle of the body. They are each placed
upon a lengthened conical peduncle, are of an ovoid shape,
and are composed of about twenty crystallines.

The first pair of antennae (t., XXII, f. e) is large, and
consists of five articulations, the last of which is short, and
terminated by several long filaments ; the second pair
(t. XXIII, f. c) is shorter, and is formed of the same
number of joints, each furnished with several setae.

The mandible is a flat plate, arnv.xl at its extremity
with three or four sharp teeth. The first pair of jaws is
composed of a large body with three or four appendages,
like fingers, armed with stout cilia, and having attached
to each a large branchial plate (t. XXIII, f. c/] furnished
with fifty finely plumose setae. The second pair (t. XXIII,
f. d] consists of an oval plate, divided into three articula-
tions, and armed with numerous short setse.

The natatory feet (t.- XXII, f. b] are peculiarly -formed
organs, having as the basilar joint a large fleshy body,
which gives oft' from its upper edge a long, slender branch,
composed of eight articulations, furnished with long plu-
mose filaments, and a small appendage from its anterior
margin, formed of two short articulations. The oviferous
feet (t. XXII, f./) are long and slender bodies, cylindrical,
twisted, divided into very numerous short joints, and
furnished near the upper third of their length with several
sharp, stout, serrated spines.

The abdomen (t. XXII, f. g) is terminated by a large'
caudal plate, which is broad, and armed at its extremity
and inferior edge with several stout serrated hooks or claws.

Very little is known of the habits and manners of these

12

178 BRITISH ENTOMOSTRACA.

curious little creatures. The two species here described
were dredged by Mr. M'Andrew from a considerable
depth, and were preserved dry ; and the species described
by me in the 'Annals and Magazine of Natural History'
as inhabiting the Atlantic Ocean, was brought on hoard
by means of the towing-net by Mr. Adams. Nothing of
their habits, therefore, could be observed by either of
these gentlemen ; neither docs M. Edwards give us any
information with regard to them.

Among the various interesting drawings of Crustacea,
however, made by Mr. Adams, during the voyage of
II. M.S. Samarang, there was one kindly placed in my
hands by him, which appears to represent another species
of this genus. It was brought on board by the towing-
net in the Sooloo Sea. Mr. Adams describes it as very
quick in its motions, darting about with great velocity,
and constantly revolving. He observed it, as well as the
above-mentioned species, to be highly luminous.

M. Godeheu de Riville, in his paper on the luminosity
of the sea, published in 1760, in the third volume of the
'Memoires pour les Savans Etrangers,' describes and
figures a small Entomostracon, which I think must belong
to the genus in question, and of whose luminous pro-
perties he gives a very interesting description. Sailing
along the coast of Malabar, when in 8° 47' north lat.,
and in 73° east long, of Paris, the sea was observed to
be unusually and most brilliantly luminous. Having had
his attention previously directed to this interesting phe-
nomenon, Riville determined to ascertain the cause. The
water all round the vessel, and to a considerable distance
from it, was white as snow ; and, in the wake of the ship,
innumerable star-like bodies of a still brighter lustre
sparkled on the surface of the agitated surf. He had
some water drawn up from alongside, and he then ob-
served numerous, bright, sparkling spots in the bucket in
\\hich it was contained. Pouring it out upon a piece of
linen, numbers of small bodies still giving out light, were
ol»er\ed adhering to the Mil-face of the cloth. They were

CYPRIDINA. 179

alive, and resembled, he says, " those small insects called
in France puces d'cau." The body of the animal was
contained in a little shell, which was transparent, and
resembled in form an almond cleft on one side, and
notched at the superior part. The animal, besides several
organs, which he shortly describes, had, he remarks, " a
large foot, armed with a toothed talon, resembling that of
the puce d'ecm, and destined for the same uses, being a
kind of rudder, which enables the insect to move about
with swiftness." Such appears as yet to be the whole
amount of our knowledge with regard to the habits of this
genus.

1. CYPRIDINA MAC ANDREI. Tab, XXII, fig. 1 a-g.

CYPRIDINA MAC ANDREI, Baird, Ann. and Mag. Nat. Hist., 2d series,

i, 21, t. G B, f. 1-7, 1847.

The shell or covering is of an oval shape, the two ex-
tremities prolonged into sharp points ; that of upper
extremity curved and projecting forwards, and a little
upwards, that of inferior extremity projecting a little back-
wards. The whole surface of the valves is dotted over with
small points, and on their anterior edge, near the upper
extremity, they are deeply notched. The eyes are ovoid-
shaped, and areolar.

The first pair of antennas (t. XXII, f. le) is of con-
siderable length, and consists of five articulations. The
basilar joint is the longest and largest ; the second is of
nearly equal size, and armed on its external edge with
five or six short setae ; the third is the shortest ; the fourth
is about twice the length of the preceding, and like it
sends off two or three short seta? at the extremities ; and
the fifth, or terminal, has at its extremity six or seven long
setae, which are not plumose. The second pair of antennae
(t. XXII, f. lc; t. XXIII, f. U-) is about two thirds
the size of the first pair, and is divided into four articu-
lations. The first, or basilar joint, is stout, and of ronsi-

180 BRITISH ENTOMOSTRACA.

derable size; the second is nearly equally large; the third
is short, about half the size of preceding ; and the fourth
is more slender, but considerably larger than the third.

' Jo

The second is beset on both upper and lower edge with
numerous stout setae, and from the junction of the third
and fourth there issues two or three long, slender iila-
ments ; while the last joint is terminated by several strong
serrated spines.

The natatory foot (t. XXII, f. 1 1} is a remarkable
organ. It is composed of eight articulations. The
first, or basilar joint, is very large, fleshy, and of a
rounded oval form. The second joint is very narrow, com-
pared with the first, and about one third of the length;
while the remaining six are short, the whole scarce 1\
equalling the second in length. From the base of each
of these seven articulations issues a long filament, whilst
from the anterior margin of the basilar joint there springs
an appendage, consisting of two nearly equal, slender
joints, the latter terminating in two blunt, crooked claws.

The first pair of jaws consists each of a square-formed
plate, furnished on the inferior edge with three or four
finger-like appendages, each provided with several short,
but stout setas, and having attached to its upper margin
a large triangular-shaped plate, armed with about fiftv fila-
ments of considerable length. The second pair (t. XXII,
f. 1 d, (1) is composed each of a short, stout body of three
articulations. The first joint is rather broad ; the second
larger, and furnished on its lower edge with three rounded
finger-like bodies, each of which sends oil' several short
setae, while the third is very short and conical, and sends
off about eight stout, somewhat serrated spines from its
extremity and lower margin.

The ovifcrous feet (t. XXII, f. I/) are organs of a very
peculiar appearance and struct lire. They are long, cylin-
drical,slender, and of a twisted form. The\ are each divided
into \ery numerous short articulations, and armed at the
free extremity \\ ith about eight or ten short, sharp-pointed
spines, which again are in their turn provided with several

CYPRIDTNA. 181

sharp setae near their extremities. They are inserted
into the body near the lower third, are first curved
upwards and backwards, and then twisted round and
downwards ; they are always inclosed within the shell,
and appear to supply the place of the second pair of feet
of the Cyprides, and no doubt answer the same purpose
as these do in them.

The abdomen (t. XXII, f. 1 y] is terminated by a broad,
caudal plate, which is large, flattish, and armed with nine
strong hooks and spines ; the six external of which are
powerful-looking talons, and are serrated on their under
edge. The first is much the longest and strongest, and
they gradually become shorter as they descend, the last
three being much smaller than the others, not serrated
on their edges, but terminated by a tuft of short setae.

It is rather remarkable that none of the long filaments
or seta?, with which the different organs are furnished,
are plumose in this species.

Hab. — Dredged in seventy fathoms, between the islands
of Lewis and Skye, R. M'Andrew, Esq. -

2. CYPRIDINA BRENDA. Tab. XXIII, fig. 1 a-g.

The shell or covering is oval, rounded at both extremi-
ties, rather narrower at the anterior, where it is deeply
notched in front, producing a kind of short beak. The
colour is of a dull white, opaque ; the valves are smooth
and tumid.

The eye (t. XXIII, f. 1 a] is large and ovoid, with about
twenty areolae.

The first pair of antennae (t. XXIII, f. 1 e) is divided
into five articulations ; the first being the largest, and
the others gradually becoming shorter as they descend,
the last sending off four long, plumose filaments. The
second pair (t. XXIII, f. 1 c) is curved, and formed of five
joints : the basilar being stout and rather short ; the second,
longer, arched on one side, and provided with tlifcetTor

BRITISH ENTOMOSTKAC v

four long, simple sctaj ; the third is the shortest of all,
with a projection on its under edge, which gives off two
stout, plumose seta.'; the fourth, longer and narrower than
the preceding, is armed on its outer edge with five simple
setae; and the h'fth is very slender, and terminated by
four short, simple spines.

The natatory feet (t. XXIII, f. 1 1} arc large, and like
those of preceding species, except that the long filaments
arc distinctly and beautifully plumose, and that there was
apparently no appendage attached to the basilar joint. The
first (f. \(/) and second pairs (f. 1 d) of jaws are of the
same structure as in C. Mac Andrei. The oviferous feet
(f. I/) are stronger than in the preceding species, and
are armed with a much greater number of spines, being
not less than twenty-four. The caudal plate is exactly
the same as described in Mac Andrei.

Hab. — Dredged in from eighty to ninety fathoms sand,
twenty miles east of the Noss in the Shetland Isles,
R. M'Andrew, Esq.

ORDER II— COPEPODA.*

CARCINOIDA (pars),Latreille, Cuv. Regiic An., iv, 151.
COPEPODES, M. Edwards, Hist. Nat. Crusl., iii, II I.
CopEPom, llnli-tl, Trans. Benv. Nat. Club, ii, 181."..
Citoi-iiYKuPODA A, Ji/'i-i.n'ixfcr, Orgiiiiiz. of Trilob. (Ray Soc. edit.), 15 1.
CKUSTACEA COPEPODA (CYCLOPACEA), Dana, Proc. Amcr. Acail. Arts and

Sciences, IS 17.

Character. — Body divided into several verv distinct
rings. Envelope consisting of a buckler, inclosing head
and thorax. Aloiitli possessed of fool-jaws. |\vt li\e
pairs in number, mostly adapted for swimming. Ovary
external.

* From KWTTI;. oar; and .TITI;, foot.

CYCLOPID^:. 183

Family 1— CYCLOP1D2E.

PSEUDOPODA (pars), Leach, Ediu. Enc., vii, 384, 1814.

Latreitte, Gen. Crust, et Ins., i; Hist. Nat. Crust., iv, 356,

(exclus. gen. Argulus).

MONOCULI (pars), M. Edwards, Hist. Nat. Crust., iii, 423, 1840.
CYCLOPIDEES, Leach, Diet, des Scien. Nat., xiv, 524 (exclus. geu. Poly-
phemus), 1819.

Desmarest, Cons. gen. sur Crust.
CrcLoriD.E, Baird, Trans. Berw. Nat. Club, ii, 1845.

Character. — Head not distinguishable from body, being
consolidated with the first segment of thorax. Foot-jaws
two pairs, generally small. Legs five pairs ; the fifth pair
rudimentary. One eye. Both antennae, in male, fur-
nished with the swollen hinge-joint.

Bibliographical History. — The first notice of any sub-
ject of this family that I am aware of, is to be found in a
little work of Stephanus Blancardus, the i Schou-burg der
Rupsen, Wormen, Ma' den, &c.' published at Amsterdam
in 1688. His notice of it is however very brief, and the
figure which he has given is very bad ; being barely
sufficient to enable us to make out that it is the Cyclops
quadricornis he means to represent.

Leeuwenhoek appears to have been the next to take
particular notice of any individual belonging to the family.
In his c Epistolse ad Societatem Regiam Anglicam,' &c.
(Epistola 12L, written in 1699) he gives numerous details
of an insect which he found in fresh water, and whose
habits he seems to have studied with considerable atten-
tion. He gives a figure of it also, which, though far from
being correct, suffices to show us that his insect is likewise
the Cyclops quadricornis. His observations upon it are
very interesting, and he discovered, among other things
worthy of note, the great difference there is between the
young and the old animals, though he did not carry his
observations so far as to trace the transformations which
take place.

IM BRITISH ENTOMOSTRAt \

In Number '2*3 of the ' Philosophical Transactions' for
January and February, 1703, the same author gi\es a
description of a polype (the Jli/drtt /-/V/V/Y.v of Midler)
growing upon the leinna, or duck-weed, which calls forth
another paper from an anonymous correspondent, in
Number 288, for November and December, 1703, in
which the writer mentions his having frequently observed
the same polype growing upon insects, especially upon
" twro sorts, of the crustaceous kind." Of these two
>pecies of animals, which he states are monoculous he gives
figures, sufficiently correct to show them to be tlaeCyclops
qitadricornis and l)i(i/)lotm'H ('ax/or, the first being a tole-
rable figure, though the second is very indiU'erciit. 'flu-
same writer also takes notice of a third animal of the
same family, which is much smaller, and like a shrimp,
but which he could never figure, evidently the Canllio-

r(H,i/)li/x nil II li I US.

Baker, in his '.Microscope made Easy,' L 74 3, makes
a few remarks upon the same animals, and copies the
figures from the 'Philosophical Transactions;' and in his
'Employment for the Microscope,' 1 7(> t, he publishes a
letter from a correspondent, who gives a variety of details
with regard to the animal which Leeuwenhoek describes,
finds great fault with his figure, but gi\es a much worse
one himself!

L)e (Jeer, in his ' M ('moires pour servir a fllistoire di -s
Insectes/ vol. vii, published in 1778, is the next author,
t believe, who has entered into any details relative to this
family. lie describes at considerable length, and figure-
\\ith tolerable accuracy, the Cyclojix <///(i</r/<-<>rnix, and
i -01 1 linns many of Leeuwenhoek's >tatemcnts respecting it,
particularly the great difference between the young and
the old animal.

Otho I'Yidcrieus M filler* is the next succeeding author
who has particularly noticed the family. Previous to his

* /(K.li.ir. D:iu. IWi-uiii., L/70; Eiitoiuobtiaca, bcu ln>n,;i 1

&c.. 1785.

CYCLOPID^. 185

time,* with the exception of detached notices, such as I
have mentioned above, one species only of this family
seems to have been noticed by authors, which, like all
the other Entomostraca then known, was arranged and
described under the general name Monoculus. He was
the first, as I have already mentioned, to divide the dif-
ferent animals which figured under this name into dis-
tinct genera ; and having discovered in the marshes and
on the shores of Denmark and Norway, a variety of
species, all agreeing in many characters with each other,
he formed them into one distinct genus, and gave the
name of Cyclops to it. He has given a number of inter-
esting particulars of many of these little creatures, but
has fallen into two or three mistakes concerning them,
which will be pointed out hereafter.

Some time after Muller, Ramdohr, in 1805, published,
in his little work on the Monoculi, f a very correct account
of the anatomy, &c. of three species found in fresh water,
accompanied with plates, which possess very considerable
accuracy, and traces their whole transformation from the
egg to the perfect animal.

Louis Jurine j (pere) some years afterwards published
his excellent monograph, and in it has given us the fullest,
most interesting, and most accurate information upon the
fresh- water species belonging to the family, of any author
who has written upon the subject. He declines the name
of Cyclops, which Miiller had given it, and prefers the old
term Monoculus ; but he has rectified the mistakes which
that naturalist had fallen into, and completed, by a series
of wonderf idly careful experiments, the previous discoveries
of Leeuwenhoek and De Geer. This he had done, with-
out even alluding to the labours of Ramdohr, and indeed

* " Uniciuu quidem aute annum 1769, quo in Synopsi Monoculorum quatuor
iiovas Cyclopes Jluviatiles public! juris feci, iiempe Monoculus quadricornis
Eiitomologis imiotuit." — Eutomost., 100.

f Beytrage zur Naturgesckichte eiuiger deutscheu Monoculus-arten. ito,
ilullc, 1S05.

J Histoire dc.-> Monocles qui sc trouvcut aux Environs dc Geneve, 1820.

186 BRITISH ENTOMOSTRACA.

seems to be ignorant of his discoveries, though the work
of Ramdohr preceded his by fifteen years.

Gunner,* Strom, f Tilesius, J Viviani, § &c. had all
noticed or described various species, previous to Jurine's
time, and several new species have been described since ;
but, subsequently to his history, no work has been exclu-
sively devoted to the Entomostraca.

Mr. Templeton, however, has added several new species
belonging to this family, which he discovered within the
tropics, and Koch has described a good many in Germany,
while M. Milne Edwards has bestowed much pains in
elucidating their systematic arrangement.

Lately Mr. Dana has added a great many species, dis-
covered by him during the American voyage of exploration
under Captain Wilkes, and has described them in the
' Proceedings of the American Academy of Arts and
Sciences' for 1847 and 1849.

Anatomy and Physiology, fyc. — The body of the animal,
which is soft and gelatinous, is inclosed within a horny
shell, which covers it like a buckler, but opens interiorly
to give issue to the antenna), organs of the mouth, and
feet. In general the thorax and abdomen are pretty
easily to be distinguished from each other, and are com-
posed of about ten segments, the thorax usually having
four, and the abdomen six. In the upper or cephalo-
thoracic segment, which is usually much the largest of all,
we iii id the eye, the antenna?, mandibles, mouth, a pair
of foot-jaws, and one pair of feet.

The eye is situate near the upper extremity of this first
M Lament, and in the centre. It is tolerably large, and is
Dingle, and in some, as in the /V/V//>/W//,v Castor, we can
perceive the muscles which move it, of which there are
M'\eral. The antenna- are four in number. The superior

:* Skril'tcr sum udi del Kiuhriihaviiskc Sclskab., Drrl x, I/'1 •

t ll.i.l., Drrl ix, [765.
: \lrmoin > ilr I'A.Mil. Imjiri. deS N/iril. ilr IVtri >l)c»liri:. V.

. riiu-.|i||iiiciili;i Minis, A.T., "

CYCLOPID^l. 187

arise from the upper portion of the segment, on each side
of the eye ; they are always larger than the inferior pair,
and are generally composed of numerous articulations,
which are plentifully supplied with short setae.

The male is distinguished by a peculiarity in the an-
tennae which at once marks the sex. Most frequently
they are shorter and thicker than in the female, and either
one (the right one as in Diaptomus Castor) or both (as in
Cyclops quadricornis, &c.) have a swelling near the centre,
or towards the extremity, followed by a moveable joint,
which acts like a hinge, and which serves a very useful
purpose in the act of copulation. The inferior antennae,
or antennules, are situate immediately beneath the pre-
ceding, and are composed of fewer articulations. Both
of these organs are made use of by the animal to assist
itself in progressive motion. Immediately below the an-
tennules is situate the mouth, in which we find a labrum
or lip, and the mandibles : these latter organs may be de-
scribed as consisting of three parts, body, neck,* and
palpiform branch, but differing from each other in several
respects in the various genera. Beneath these, again, are
situate the jaws, which are almost obsolete in this family.

Below the mandibles are situate the foot-jaws, which
Jurine calls hands ; a term which Muller had already ap-
plied to the same organs in one marine species he describes,
the Cyclops chelifer.^ These organs are always situate
in the same place, but all differ from each other in so
many respects that it will be necessary to describe them
in the species of each genus separately. The use of these
organs, according to Jurine, is to push constantly towards
the mouth a current of water, carrvino; along with it the

€/ O O

particles destined for the animal's food. Immediately
beneath the foot-jaws are situate the first pair of feet.
They are double, consisting of two stalks arising from a
common base, each stalk consisting generally of from two
to four articulations, more or less furnished with setae,

* Prolongation of Jurmc. f Entoino.it., p. Hi.

188 BRITISH EXTO-NIOSTRACA.

but varying very much in the different genera. Attached
to the next three segments of the thorax, and arising
from the interstices between each, we find three other
pairs of double feet, in general resembling each other
exactly, and adapted solely for the purpose of swimming.
The fifth pair is very small, nearly rudimentary. It is
attached to the first segment of the abdomen, and is
larger in the female than in the male. It (lifters some-
what in appearance in the different species, and as its
use was supposed by Jurine to be, to give support to the
oviducts which furnish the envelope of the external ovaries,
has been called by him " les supports ou fulcra."

The female organ of generation or vulva is placed in the
abdomen also, at the junction of the second segment with
the third ; this opening forms also the mouth of the
1'iiiKilis dcfrri'i/x, which communicates directly with the
internal ovary, and gives passage to the eggs. In most
of the species the male organs appear to be situate in the
first segment of the abdomen, though in the Ci/clo/w
(//tf/r/rirontix we find them in the second. The external
ovary, or bag of eggs, springs from where the second
segment articulates with the third, and is attached to it
by a very slender pedicle. The internal ovaries consist
of an opaque mass of solid looking matter, composed of
numerous round globules of a dark-brown colour, dis-
posed round the alimentary canal, and occupying a con-
siderable spare of the interior of the body. This, as I
have already stated, has a direct communication with the
opening at the junction of the second with the third
segment of the abdomen, the <-:ni(tl'ix ili-ffrcnx of Jurine;
and it is through this canal that the eggs pass into the
external ovary.

The alimentary canal is very perceptible, beginning
behind at the place which I have mentioned as the situa-
tion of the lips, and terminating at the extremity <>f the
abdomen win-re the tail commences. The tail consists
of a bilid segment, \\ Inch is generally short and terminates
m t\\n or more long sel;e.

OYCLOPID/E. 189

The species belonging to this family are to he found
both in fresh water and in the sea. The fresh-water
species abound in the muddiest, most stagnant pools, and
in the clearest springs, and the ordinary water with which
the inhabitants of London are supplied for domestic
purposes often contains them in great numbers. The
marine species are to be found frequently in immense
quantities in small pools on the sea shore, within high-
water mark, living among the sea-weeds and coral-
lines, which so elegantly fringe the beautiful little wells
and clear round pools which are hollowed out in the rocks
on the coast, and are to be met with in equal profusion
in the open ocean, where, by the curious luminous pro-
perties they possess, they assist in producing that beautiful
phosphorescent appearance of the sea, which formerly
puzzled naturalists to discover the cause of. It is
amazing when we examine the pools of water in our
fields or sea shores, to find such infinite myriads of little
creatures sporting about in all the enjoyment of existence;
and it is exceedingly curious and interesting to know the
extraordinary fertility of such apparently insignificant
creatures. Specimens of the Cyclops quadricornis are
often found carrying thirty or forty eggs on each side ;*
and though the other species, which have only one external
ovary, do not carry so many, still the number is very
considerable. J urine has with great fidelity watched the
hatching and increase of the Cyclops quadricornis in par-
ticular, and has given a calculation which shows the
amazing fertility of the species. He has seen one female
isolated lay ten times successively, but in order to speak
within bounds, he supposes her to lay eight times within
three months, and each time only forty eggs. At the
end of one year this female would have been the progenitor
of 4,442,189,120 young ! ! The first mother lays 40

* Leeuweuhoek says, that in the specimens which occurred to him of the
quadricornis, he counted the eggs iu the ovary and found them arranged
three or four in breadth, and nine or ten in length. — Epist. ad Soc. Reg.
Aug., p. 13S.

190

BRITISH ENTOMOSTRACA.

eggs, which at the end of three months, at eight layings
during that time, would give 320 young. Out of this
number he calculates 80 as males (there being in even
laying a great proportion of females), the remaining 240
are females.

The following table will show the prodigious extent of
of their fecundity :*

No. of

liiyiii.L's.

Time unj'Mu-i] fur
those tvlit hi\ -

TOTAL.

Kuril l.iuii'.' *ll]>-
jMISC'll tO III

young.

Sulitriic-t for

males.

Females
rema

1st mother .

•{

From 1st Jan. to
end of March

} 320

80

240

1 st family of fe-
males 210

H

From 1st April
to end of J uuc

76,800

19,200

57,600

3d family of fe-
males 57,600

W

From 1st July to
cud of Septem.

} 18,432,000

1,608,000

13,821,000

3d fam. of fern.
13,821,000

}•{

From 1st October
to cud of Dec.

}4,423,6SO,000

1,105,920,000

3,317,760,000

i,! !-MS<),U'II

1,110,547,28013,331,641,840

A single copulation suffices to fecundate the female for
life. The male seems very ardent in his amours. By
way of prelude, he seizes hold of the hinder feet of the
female with his antenna*, which being furnished at its ex-
tremity Avith the hinge-joint already described, forms a
fastening round her feet, which she cannot loosen by
any exertion, and thus he is carried about with great
rapidity for some time. The female, however, at length
stops, wearied by her exertions, when the male seizes the
favorable moment, and in the twinkling of an eye; (as
.liiriue expresses it) makes a double copulation, one on
each side. According to M idler, the male organs are
situate in the swellings which we perceive in the antenna1
of that sex, and which are characteristic of it. Carried
away by the analogy of the Arachnidie. and seeing the
male take hold of the lo\\er part of the female with his

' .lunnr, 1 list, <lrs Mmior. \r.. \>.

CYCLOPIDJE. 191

antennae, he immediately conjectured that the organs re-
sided in the swellings which mark the antennas of the
male, and were applied to the vulva, which he correctly
enough states to be situate in the abdomen.* This mis-
take, however, Jurine has cleared up, having demonstrated
the organs in both sexes, and watched the act of copula-
tion itself. When the mother is about to lay, we may
perceive the material of the eggs, which I have described
above under the name of internal ovary, divide into two
columns, one on each side, and pass through the canalis
deferens, covered with a fine pellicle, which forms the sac
in which the eggs are contained when extruded. This
bag of eggs, or external ovary, remains suspended at the
tail of the female for several days, varying from two to
ten, according to temperature of weather, &c.f The eggs
themselves, during their sojourn there, do not increase in
size, but undergo various changes in colour, &c., and at
the proper time the ovary opens, and the young ones are
ushered forth into life, as unlike the parent as can well be
imagined. I have already said that Leeuwenhoek has
noticed this difference between the young and old, and
upon first observing it, he appears to have been much
surprised at the unexpected discovery. He repeated his
experiment, therefore, of separating an insect, with the
ova attached to the tail, and found the same result : "Ex
hisce visis," he concludes, "certa mihi persuasi ea ani-
malcula, quae jam oculis meis observabantur, ex ovis illis
nata esse." j He watched them for seven or eight days,
and found them increased in size ; but here, when just on
the threshold of discovery, he seems to have stopped, and
he makes no further mention of a continuation of his
observations.

De Geer also noticed this curious fact, confirms the
observations of Leeuwenhoek as far as they went, gives

* Entomost., pp. 16, 1 7.

•f Leeuwenhoek says they extrude their ova in the space of one day or
night, and bring them to perfection in the space of three days. — Epist. ad
Soc. Reg. Aug.

£ Epist. ad Soc. l!eg., p. 139.

BRITISH KNTOMOSTIMOA.

figures of the young :it d'.fl'ercnt. stages of their growth ;
but after having watched them for about tifleen days, he
likewise appears to have desisted from further inquiry.

Notwithstanding this, M filler could not persuade him-
self that such dissimilar creatures could be the same
animal, and he has accordingly, without giving sufficient
credit to these illustrious men, or watching the hatching
and progress of the young himself, formed these imperfect
creatures into two distinct genera, which he has called
Ts'auplius and Amymone.* Hamdohr and Jurine, how-
ever, have both rectified this mistake, and fully corrobo-
rated the assertions of Leeuwcnhoek and !)c fJecr, by
following out the transformations in all their extent.

The time occupied in this process varies much accord-
ing to the season of the year and the temperature. This
latter 1 have found produces an amazing difference in the
duration of the period so occupied, and 1 have no doubt
also, from myown experiments, that the process has been re-
tarded or hastened, just as thevessel in which they have been
kept has been placed in a light or dark situation. Jurine
says, in the case of the Ct/clops f/trf///ricor/iix, this process
has always lasted twenty da\ s ; and in a scries of very care-
ful experiments which he made in February and .March,
he found it extend to twenty-eight da\s. For the first
eight days they underwent little or no change ; between
the eighth and thirteenth, the body appeared a little more
elongated : between the thirteenth and nineteenth, the
Hue of demarcation between this increa.se of length and
primitive si/e was traceable by a line of a brown colour,
and the insect had acquired a third pair of feet : between
the nineteenth and twenty-fifth, no great change took

* Entomost., pp. 39-4:8. It is staled 1>\ Ldreille, and echoed l>\ some

other \\riters, Iliat the Amymmir of Mnller is the vnimi: of 1 lie ( '\elops. in
its earliest -lute, \\lien it lias as \et onK fmir leirs, and lliat \\lien it reeeixes
llic additional pair it thru becomes llie Xanplins. This i.s not correct. The

diil'creiit species nf ilic Ain\ nnn'c arc the young of the (7. minutus in differenl

. and of one in- I \\ o marine species; and never assume the form nl the

Nauplius.

e <'i/c/<i/

' Midler. Tlie .\,ntf,liiis 1,,;i,-t,;ilns 1 lia\e ne\er -i'i-|i, and dn ii'il know.

mplins. 'I'he Nanplins (at least ilie Navplius saltatorius) is the young of
i he Cyclops quadricornis, \thich &\ its earliest stage resembles fig. 3 of plate I

CYCLOPIIKE. 103

place, only the third pair of feet were more developed ;
between the twenty-fifth and twenty-eighth, the first
moulting took place ; and thirteen days afterwards they
moulted a second time.

In a, series of experiments which I undertook, upon the
same species, in the end of June and beginning of July,
when the thermometer was frequently above 80° during
the day, I found the time occupied in the process in some
instances very much shortened. In one brood, which
were hatched on the 21st of June, I found some had com-
pleted their first moulting on the 1st of July, or on the
eleventh day. In another brood, hatched on the 22d of
June, I found the same result, several of the young having
completed their first moulting on the 2d of July. On the
4th I could only see one that had not moulted ; and next
day, the 5th, this one had also undergone the change.
The second moulting in many of them took place only a
few days after the first. In another brood, hatched a
little earlier in June, when the weather was not so hot, I
found the changes took place as follows : When hatched,
the insect appeared of an oval shape (t. XXIV, f. 7), having
two thick antenna?, of three articulations each ; two pairs
of feet, bifid at extremity ; in the upper pair, one division
consisting of two and the other of only one articulation ; in
the lower, both divisions having only one articulation.
Extremity of body furnished with two short setae on each
side. On the eighth day (t. XXIV, f. 8), the body was con-
siderably elongated, and a well-defined line now showed
the distinction between this increase and original size.
Some traces of setse also had appeared, where the third
pair of feet afterwards spring ; intestine very distinct. On
the fifteenth day (t. XXIV, f. 9), the third pair of feet had
become visible ; the lower part of the body more elongated,
the elongation marked by another line of demarcation.
The setae on the edges of the antennas were now per-
ceptible, and those of the feet longer and more numerous,
whilst the second pair of feet had the upper division of two
articulations. On the seventeenth day moulting had taken

13

194 BRITISH ENTOMOSTRACA.

place (t. XXIV, f. 10) ; the body was divided into two seg-
ments, abdomen into three, the terminating one cleft at
extremity, each cleft sending oft' ;i long seta; antennae of
about six articulations ; the antennules had become dis-
tinctly visible, and the feet had assumed the appearance
they afterwards bear. At each moulting the number of
segments into which the body and abdomen are divided
increase in number. The number of articulations and
the length of antennae increase, &c. ; but it is not until
after the third moulting that the animal is perfect
(t. XXIV, f. 3), and capable of producing its species.

A question lias been started, whether the Cyclopidae
should be considered oviparous or viviparous ; and it ap-
pears to be one of some difficulty, as they would seem,
from what I have stated, to be both. Geoffroy asserts
that all the Monoculi are oviparous.* De Geer also says
they are oviparous. " However," he immediately adds,
" as the Monoculi never quit their eggs before the young
ones are hatched, we may perhaps regard them as vivi-
parous. "f J urine says it is difficult to decide. Vivi-
parous young, he remarks, increase in size every day, and
have constant need of a mother's care — if she die, all die ;
but as the young of the Cyclopidse do not increase in size
after passing from the internal ovary, and as, from nu-
merous experiments which he details, they were found,
after having passed into the external ovary, to be inde-
pendent of the life of the mother, even if she were killed
by spirits of wine, they must, he concludes, be considered
oviparous.!

The process of moulting, under which the little creature
frequently succumbs, is both interesting and curious.
The new shell or covering having grown under the old
one, when the process of changing it commences, the in-
sect fastens itself to the bottom or side of the vessel in
which it is, or to any solid object near it, so as to give

1 1 1st. alinV- (l('s Tnscctcs, (\~i\.
t Mmi. pour scrv. a 1' I list, dcs Ins., vii, 435.
j: HIM. Mat. »!<•* Mmioc., 17.

CYCLOPID.E. 195

itself support ; it then, by moving its limbs and shaking
the valves of the shell, the new parts at the same time
coming forward, loosens the old covering, and in a short
time frees itself from the exuviae altogether, leaving behind
the sheaths of the limbs, hairs, plumes, and even the minute
setulae, that almost escape the power of the microscope
itself from their fineness, such as the delicate plumose
setce which adorn the filaments of the tail. " How far
beyond all idea this most subtle fineness !" says Miiller,
from whom I have taken this description ; "for they are
sheaths containing other smaller sheaths, which again in-
clude other organs smaller still."*

The number of times they moult during life is not
known ; but Jurine says, they ordinarily, though not
always, moult before each time of laying eggs. They cer-
tainly do not always do so ; and perhaps the frequency of
their moulting may depend much upon the temperature,
the season, &c.

Having the experiments of Spallanzani and others,
upon the reproduction of mutilated members in various
animals, in his eye, M. Jurine instituted a series of expe-
riments upon the Cyclop* quadricornis, to see how far this
power existed in this family. In his first attempts he
failed, the animals having died before they moulted, and
without showing any evident change in the mutilated
members. At length, however, he succeeded. He cut
off about two thirds of an antenna in a female, which
lived and moulted, reappearing after moulting, with
beautiful, perfect, new antennae, the old one of the cast
shell not having shown the least indication of a change, f

Some authors have asserted that these insects possess a
wonderful power of resisting drought, and that when, by
reason of the summer heats, the marshes become dried up,
the little creatures do not die, but as soon as the mud is
again moistened by the rain, they recover entirely. Jurine
doubted this, and commenced a course of observations to

* Entomost., p. 9. f Hist, des Morioc.,

'

<fr~ -*-'

19G BRITISH EXTOMOSTRAf \.

prove that they have not this faculty. He selected twelve
of the ('//r/n/jx /ii't/dricorti/s, removed them out of the
uater, and allowed them to remain fifteen minutes dry;
seven of them he found to be irrecoverably dead ; the re-
maining five revived. Again, he selected t\\rl\v others,
and allowed them to remain twenty minutes dry; eleven
out of the twelve died. A third time he selected twelve,
and after exposing them to the air in a dry state for twenty-
live minutes, he found that all had perished.*

These experiments, notwithstanding, are not quite con-
clusive, for the mud in which they are enveloped, and in
which they are very gradually dried, while in their native
habitats, might retain a certain degree of moisture suf-
ficient to prevent life being utterly extinguished; and
I have accordingly found, upon examining ponds which
had been filled again by the rain after remaining two
months dry, numerous specimens of the Ci/do/)* qitadri-
coruis in all stages of growth. Their power of resisting
the action of cold, however, according to Miiller, is much
greater than their power of defying drought. In an
experiment which he details, he says that he exposed
some individuals of the Cyclops guachricornis, in a glass
vessel, to a freezing air, and that when fully frozen, he
continued the exposure for twenty-four hour-;. At the
end of that time he placed the vessel containing their
frozen bodies in a warm bath, watching the effect of this
upon them frequently during the succeeding twenty-four
hours, but without seeing any motion. Next morning,
ho\\e\er, upon looking into the vessel, he observed, not
without wonder, the insects alive, and swimming about as
before congelation, the females with their bags of eggs
adhering to them as usual ;f but although they did not all
recover, the greater par! were restored to life.

In some other similar experiments upon these little
creatures, throwing them into a stale of asphyxia by

• us of .-spirits of wine, and then restoring them to life

* P. 39, f l. pp

CYCLOPID.B. 197

again, Jurine found that the first part of the body to
show irritability and a return of motion was not the heart,
as perhaps might be expected, but the alimentary canal ;
the heart seems to be the next, then the antennae, and last
the feet.

De Gcer asserts, that the Cyclopidae, along with the
other Monoculi, are nourished by animalcules. Leeuwen-
hoek, in addition to this, asserts, that when deprived of
other food, they devour their own young. De Geer also
says that he has seen this frequently to be the case.
Jurine has repeatedly witnessed the same ; but says, in
vindication of his beloved insects, that it would appear
from what he has noticed, that they do not do so from
taste, but that the helpless young cannot resist the action
of the whirlpool the mother causes around her, and are
carried unconsciously into her mouth.* I have also ob-
served the sudden disappearance of the young when no
other animals were in the vessel but their mother, and
who, it is most probable, must have devoured them ; and
from what I have noticed, I think the variety albidus of
the species guadricornis, is the one which possesses this
carnivorous propensity in the greatest degree. Miiller,
however, maintains that the Cyclops quadricornis, as well as
others of the Entomostraca, live upon vegetable food ; and
I have mentioned above (p. 5) the experiment he insti-
tuted upon the subject. f But notwithstanding this, it is
evident he labours under a mistake • and there is every
reason to presume, that their being carnivorous serves a
most useful purpose in the economy of nature. The
adults, in their turn, fall victims to and are devoured by
other insects, the chief of which are the Hydrachnae,
Hydras, and larvae of aquatic insects, which destroy them
in such vast numbers, as in some measure to counter-
balance the most extraordinary fertility which they
possess.

* Vide the observations of M. July upon the Artemia saliva, supra, p. 59.
f Geoffrey also says that all the Monoculi live upon vegetable matter
alone. — Hist, abreg. des Ins., ii, 651.

198 BRITISH ENTOMOSTR.U \

This family contains the following genera: —

1. CYCLOPS. — Foot-jaws large and strong-branched;
antennules simple; ovaries double.

2. CANTHOCAMPTUS. — Foot-jaws small, simple; anten-
nnles simple ; ovary single.

3. ARPACTICUS. — Foot-jaws forming strong cheliform
hands; antennules simple; ovary single.

4. ALTEUTHA. — Foot-jaws small, simple ; body flat ;
two strong falciform appendages from fifth segment of
body.

Genus 1 — CYCLOPS.*

CYCLOPS, MitHer, Lati-eillc, .Desman1*!, M . l-Iifirards, Koch, &c.
MOXOCULUS, Linnteus, Fubficius, J urine, &c. &c.

Character. — Foot-jaws large and strong, branched.
Antennules simple. Ovaries double. Both antennae in the
male possessed of the swelling and hinge-joint.

1. CYCLOPS QUADRICORNIS. Tab. XXIV, figs. 1-10.

MONOCULUS QUADiucoRNis, Linnaus, Faun. Suec., No. 2049, 17 Hi:

Syst. Nat., edit. 10th, i, 035, No. G ;

edit. 12th, 1058, No. 0.
Gmelin, Liuii. Syst. Nat., edit. 13th, i,

2996, No. 6.
Scopoli, Eutomologia Cariiiolica, 413,

No. 1139.

Fabricius, Syst. Entomol., 295.
Jm-uii; llisl. .Nat. .Monoc., 149, 1. 1,2,3.
Sulze.r, Iiisectcu, t. 30, f. 9 b.
Donovan, Ilist. of Brit. Ins., i, 7, t. 2,

r. 1-5.

lilHuii'ii/iiifli, Haiulb. der Naturg., 399,

No. !.

Ma,//', 'I, Ki 10. iiu'tli., vii, 718.
^//•/////,(icn.Iusect.Liiiii.,ial).xx,gcu.xi.
Mime, Nal. Misccll., xxi, t. 904.

MM^OCULUSAPVS, /VA/, Insect. M UN. (Jni-cciis., 125, t. l,f. 11, 12,1761.
LE MONOCLE A QUEUE nu i;< in i:, Cn'«(f,-i>>i, lli^t. abn't,'. Ins. 1'ar.,

ii, 656, No. 3, t. 21, f. 5,1761.

l\ri.\Mi// — from k-i'K\<i<;, orliis ; anil

CYCLOPS. 199

LE MONOCLE 1 QUATRE CORNES, De Geer, Mem. serv. a 1'Hist. Ins.,

vii, -483, t. 29, f. 11, 12 (adult) ;
t. 30, f. 5-9 (egg and young).
CYCLOPS QUADRICORNIS, Midler, Zool. Dan. Prod., 2416, 1776;

Entomostraca, 109, t. 18, f. 1-4.
Ramdolir,¥>cyi. zurNaturg. einig. Deutsch.
Mouoc. art., 1-6, 1. 1, f. 1-10, t. 2, f. 1-3.
Latreille, Cuv. Regne Aiiim., iv, 158; Hist.
Nat. gen. et part. Crust., iv, 262; Genera
Crust, et Ins., i, 19.

Base, Mem. d'Hist. Nat. Crust., ii, 258.
Lamarck, Hist. An. s. Vert., v, 188.
Baird, Mag. Zool. andBot.,i, 321, t.S,f.l-14;

Trans. Berw. Nat. Club, ii, 154.
Leach, Ediu. Eucyc., vii, 383, art. Crustac.
Koch, Deutsch. Crustac., ii, t. 21.
CYCLOPS GEOFFROYI, Samouelle, British Insects, 81.
CYCLOPS VULGARIS, Desmarest, Cons. gen. Crust., 362,t.53,f.l-4,1825.
M. Edwards, Hist. Nat. Crust., iii, 425, t. 37, f. 19.
— Leach, Diet. Sc. Nat., xiv, 539.

Baird, Trans. Berw. Nat. Club, i, 97, t. 2, f. 3, 21

(the young.)

Garner, Nat. Hist, of Staffordshire.

PEDICULUS AQUATICUS, Baker, Employm. for Micros., 383, 1. 15, f. 1-4.
SATYR, Baker, 1. c., 1. 12, f. 23-26 (the young).
NAUPLIUS SALTATORIUS, Miiller, Zool. Dan. Prod., No. 2378 ; Ento-

most., 40, t. 1, f. 3-7 (the young.)

FOTJR-HORNED CYCLOPS, OR SMALL WATER-FLEA, Pritchard, Mid'OSCOp.

Cab., 91, t. 9, f. 1, 2.

De Geer, Kougl. Svensk. Vetensk. Acad. Hand., viii, f. 2, 3.
Eichhorn, Beyt. zur Naturg. der kleinst. Wasser., 54, t. 5, f. m, n.
Roesel, Der Insecteu Belust., iii. 606, t. 98, f. 1, 2, 4.*
Baker, Microscope made Easy, 93, t. 9, f. 1, 2.
Leeuwenhoek, Epist. ad Soc. Reg. Augl., 142, f. 1, 2, 3.
Blancardm, Schou-burg der Rups. Worm. Ma' den., 151, t. 13, f. B.
Joblot, Observat. d'Hist. Nat., t. 14, f. c.
Der Naturforscher, Stuck v, 247.
Neue Maunigfaltig., i, 640, f. 3.
Philos. Trans. No. 288, f. 5.

The figure of the Cyclops is given in this plate by Roesel, chiefly as
being the resting-place for a species of polype wliich he describes, and with
which, as often happens, the body of the little creature is almost completely
covered.

200 BRITISH ENTOMOSTHACA.

The thorax and abdomen are very distinct from each
other ; the former being twice the size of the latter. The
thorax is composed of four segments, the abdomen of six ;
but, in the female, the second and third are so united as
to appear only one. The last segment terminates in two
lobes. The first segment of the thorax, to Avhich the
head is imiuoveably fixed, and with which it is perfectly
consolidated, is much larger than any of the others,
being equal in si/c to all the other three ; the second
and third are nearly equal in size, and the fourth is the
smallest.

The antennae consist of numerous articulations, amount-
ing to twenty-six ; each articulation throws forward a seta,
sometimes two. In the male (t. XXIV, f. 1) they are shorter
than in the female*, and they each possess a peculiar swelling
about the middle of their length, followed by a sudden
contraction, the first articulation of which forms a hinge-
joint. If we throw the animal into a state of semi-
asphyxia by placing it in a mixture of spirits of wine and
water, we perceive these antenna1 turn round in a con-
trary direction to what they ordinarily do when in their
native element, and curving their extremities at this
hinge-joint, they bend back the part beyond it upon the
swollen portion. The anteiiniiles are divided into four
articulations (t. XXIV, f. a), each furnished with several
seiie ; the terminating one having six of unequal length.

The mandibles (t. XXIV, f. tj) are composed of three
parts, body, neck, and palpiform branch.

The body is of an ovoid shape, convex on the upper,
and concave on the under surface, in which concavity is
lodged its motor muscle. The neck is a sort of petiole,
turned upon itself, and dilated at its extremity, in which
are implanted six tolerably strong teeth. The palpiform
branch consists of one ring, and two long filaments.

A little bi hind the mandibles we see the anterior, or
first pair of foot-jaws (t. XXIV, f.r), which are strong organ*.
e;ich composed of a pretty large body, convex externally,
:iud conca\c internally. giving origin to two processes, the

CYCLOPS. 201

e»

largest of which is terminated by two or three strong
horny teeth. The posterior or second pair of foot-jaws
(t. XXIV, f . d, e) are divided to the base into two parts ; the
internal (f. e), which J urine (who calls these organs hands)
compares to a thumb, is much smaller than the other, and
is formed of three articulations ; the first of which, much
the longest, has on the inner edge several rather strong,
plumose spines, or setae ; the second, very short, sends off
one long spine ; while the third, which is the smallest, is
terminated by three spines. The external division (f. d)
is also composed of three articulations, at the base of
the first of which is attached the thumb ; this joint is
much the longest, and has on internal side two tubercles,
from each of which issues a plumose spine, while a third,
longer, springs from near its articulation with the second
joint. This second joint is in form of a strong claw, and
has attached to its upper edge the third joint, in form of
a claw also, but much smaller than preceding. These
claws are called fingers by Jurine.

The feet are ten in number, or five pairs. Four pairs
spring from the four thoracic rings, and are all alike.
Each foot is double, or composed of two branches, arising
from a common base (t.XXIV,f./) ; each branch consists of
three articulations, and each articulation is furnished with
plumose setae, the terminating one having six or seven.
The first segment of the abdomen is very small, and has
the fifth pair of feet (t. XXIV, f. y] attached to it. These
are quite rudimentary, and differ in the two sexes. In the
female it consists of a short body, of two segments ; the
first broader, and giving off from its outer edge a sharp
spine ; the second narrower, giving off from its internal
edge a short spine, and terminating inferiorly in a long,
slightly-curved spine. These organs are what Jurine
describes as the "fulcra, or supports." In the male they
consist of an oval body, composed of three segments,
diminishing each in size as they descend, and terminating
in a sharp, prolonged point. These were considered the
male organs by Jurine. The second is the largest.

202 BRITISH ENTOMOSTRACA.

In the female, as I have already mentioned, the second
niid third arc united; and running across its centre, we
may see a small canal which opens on each side where
the external ovary is given off, and in all probability fur-
uislies the envelope which contains the ova. This canal
has a direct communication with the internal ovary.

The tail consists of two long lobes, making it appear
bifurcated, each lobe giving origin to four plumose setae,
the two intermediate of which are much the longest, and
have near the upper extremity a small joint, which adds
much to the suppleness of these fine organs.

The internal ovaries are tolerably large, and divaricate.
The external ovaries, of the same colour as the adult, con-
tain in old females thirty or forty eggs on each side. The
length of this species is from f^th to fUh of an inch.

The Cyclops quadricornis differs very much according
to age, locality, &c.* J urine enumerates seven distinct
varieties in the neighbourhood of Geneva. I have met
with several in the vicinity of London, which I have been
sometimes almost tempted to consider as distinct species.

Var. a, elonyatus. — Ramdohr's figure corresponds
exactly to this variety. It is of a dull gray colour, and is
of an elongate and narrow form. The thorax, abdomen,
and caudal segments, as well as the long filaments attached
to the tail, all partake of the same general elongate figure.
The antennae, however, are a little shorter than in the
other varieties. The segments of the thorax and abdomen
arc more distinct (t. XXIV, f. 3.)

CYCLOPS QUADRICOUMS, luiniifuhr, Bcitragc, t. 1, f. 1.

— /\ «<-/i, Dcutsch. Crust., h. xxi, t. 11.

CYCLOPS AGILIS, Koch, 1. c., b. xxi, t. 3.

Var. h.— Jurine's figures of the vars. yv//;o/\,
and /-//vV//\ ji^rce with this variety. It may lie considered
the type <.!' the species. The thorax is more or less com-

* " \ ,in:il Oolore albida, fuKr.srriiir, \iridi i1) rulim." — Mull., 1. c., p. 112.

CYCLOPS. 203

pletely oval in form, and more rounded than in preceding
varieties. The caudal segments and filaments are rather
shorter and thicker, and the antennas longer. It varies in
colour according to locality, &c. Sometimes it is of a red
colour, sometimes of a dull white; and at others of a green,
more or less deep. The external ovaries are carried
diverging out from the abdomen more or less at a right
angle with it (t. XXIV, f. 4.)

CYCLOPS QTJADRICORNIS, vars. RUBENS, ALBIDUS, and VIRIDIS, Jurine,
Hist. Monoc., 1. 1, f. 1-11 ; t. 2, f. 1-9 ; t. 2, f. 10, 11;
t. 3, f. 1-3.

CYCLOPS PICTTJS, Koch, 1. c., li. xxi, t.l.

CYCLOPS PULCHELLUS, Koch, 1. c., h. xxi, t. 2.

CYCLOPS VULGARIS, Koch, 1. c., h. xxi, t. 4.

CYCLOPS OBSOLETUS, KocJi, 1. c., h. xxi, t. 5.

CYCLOPS BISTRIATUS, Koch, 1. c., h. xxi, t. 7.

CYCLOPS LUCIDULUS, Koch, 1. c., h. xxi, t. 10.

Var. c. — The figures given by Jurine of his varieties
fiiscus and prasinus agree with this variety. It differs
from the last, chiefly in its carrying the external ovaries
close upon and covering part of the abdomen. They do
not appear ever to divaricate, either when the animal is at
rest, or swimming. The inner edge of the caudal seg-
ments are beset with short, stout setae ; the antennae are
somewhat longer, and the last two joints of the antennules
are considerably longer than in either of the two preceding
varieties (t. XXIV, f. 5.)

CYCLOPS QTJADRICORNIS, vars. FUSCUS and PRASINTJS, Jurine, Hist.

Monoc., t. iii, f. 5.
CYCLOPS PHALERATUS, Koch, Deutsch. Crust., h. xxi, t. 9.

Hab. — In ponds and ditches; common everywhere,
almost all the year round.

BRITISH EXTOMOSTRACA.

Genus 2— CANTHOCAMPTUS.*

HoNOCULUS, Linnieus, Fabricius, J urine, &c>

CYCLOPS, Mi'Ui'f, Rumilnkr, Lati-fillc, Desmarest, &c.

CYCLOPSIXA (pan], .'/. /;''///v//v/\.

CANTIKXAMHS, n~rxtir<,0(J, Partington's Cyclop. Nat. Hist. art. Cyclops;

The Entomologist's Text-Book, 115.

CANTHOCARPUS (icrongly quoted}, Baird, Trans. Berw. Nat. Club, i, 97,

and ii, 15 1 ; .Mag. /ool. and Bot., i, 326.

HARPACTICUS (pars), Dana, Proc. Aoicr. Acad. Arts and Sc., 1S-17.
N AUPLIUS, riiilipiii, Ann. Mag. Nat. Hist., 1810 ; Wiegin. Archiv, 18-i3.

Character. — Foot-jaws small, simple. Antennules
simple. Ovary single, f

1. CANTHOCAMPTUS MINUTUS. Tab. XXV, figs. 4-8;

XXX, fig. 3.

CYCLOPS MINUTUS, Miille,; Zool. Dan. Prod., No. 24-09, 1776;

Eutomostraca, 101, t. 17, f. 1-7.
Ramdohr, Bcyt. zur Naturg., 10-13, t. 3, f. 1-9.
LntrrUlc, Hist. Nat. Crust., iv. 265.
Base, Mem. Hist. Nat. Crust., ii, 257.
— l.,n,iii,-i-k, Hist. An. s. Vert., v, ISO.

* From ciKavQa, a spine ; and K«/< --or, flexible.

f M. Eduanls includes the Cyclops •m/iii'inx of Midler in his genus
Cyclopsina. The anteimules, however, are not branelicd ibinmu'rs) as they
arc in Ci/rlnps Citxtor, which is the character upon which the genus C\rl<ip-
sina is i'oiinded ; and ihcn-tnrc it nnijst I'orm a separate gi'iius. The name
CiiittliiK-tiin/ittix was proposed fur it \>\ .Mr. Westwoodj MHIIC \iars a^o, from
Hie llexilile. Imrnv appeiidatre attaehed to the abdomen of the female. In
I'artinglon's Cyeli.pa'dia, art. Cvelops, and in the 'Entomologist's Text-
Book,' this genus is indicated by Mr. \\YM\vood, but misprinted Caiitho-
runijiu* ; and it was farther misnamed by myself (ipiotin^ it from memory)
in the 'Trans. Ber\v. Nat. Club,' i, r,//,///,»Y//y^/\ .• re|iriHlneed au'ain in liie
'Mat;, '/oul. and Hotaiiy,' and in the second vol. of the ' Uervv. ( 'lub Trans.'
riiili])pi, in the Arehi\, uf \\ie-inannand Kriehsen for Is 13, eoiiiirm.s my
\alinns upon the structure of the auteiiiiules, and the propriety of
separating the species from the u'enus ('i/r!<, /,.•</,/,> of Edwards. Jle forms nf
it, and some other species allied In it, the L'vnns .\,//i/lli/ifi. As that name
was used b\ Midler for the young uf the Lrenus ( '\eliips, and as the genus
din/In,,;!,,!!,/!"* \\as shortly characterised by .Mr. \\cM\\ood in the work
quoted above as eai'K as 1 ^'.\l\, I ha\ei;i\eu the preference to Mr. \\cst-
w I's appellation, as having the jiriority in date. 1'liilippi, monover, in-
cludes the veniis Harpacticus vn his Navplivt.

CANTIIOCAMPTUS. 205

CYCLOPS MINUTUS, Baird, Traus. Berw. Nat. Club, i, 97, t. 2, f. 1,

19, 20, and ii, 154 ; Mag. Zool. and Bot., i,
326, t. 9, f. 1-14.
MONOCULUS MINUTUS, Gmeliti, Linn. Syst. Nat., edit. 13th, i, 2997,

No. 11.

Fdbricius, Ent. Syst., ii, 499, No. 45.
Manuel, Encyc. meth., vii, 719, t. 267, f. 2-6.
MONOCULUS STAPHYLINUS, Jurine, Hist. Nat. Mouoc., 74-84, t. 7,

f. 1-19, 1820.

CTCLOPS STAPHYLINUS. Dcsmarest, Cons. gen. Crust., 363, t. 53, f. 6.

Baird, Trans. Berw. Nat. Club, i. 97, t. 2, f. 1

(adult) ; t. 2, f. 19, 20 (young).

SMALL CYCLOPS or VAULTER, Pritchard, Microscop. Cab., t. 9, f. 5.
Eichhoni, Beyt. zur Naturg., 53, t. 5, f. K, L (adult) ; t. 3, f. p (young).
Philos. Trans., No. 288.
Naturforseher, Stuck vii, 101.

AMYMONE SATYRA and BACCHA, &c., Midler, Entoniost.,42, t. 2 (young) .
DER SATYR, Kohlers, Naturforseher, x, 103, t. 2, f. 10 (young).

Pritchard, Micros. Cab., t. 8, f. 2.

CYCLOPSINA STAPHYLINUS, M.Edwards, Hist. Nat. Crust., iii, 428.
CANTHOCARPUS STAPHYLINUS, Baird, Trans. Berw. Nat. Club, ii,

154, 1843.

NAUPLIUS MINUTUS, P//ilipp'i,Wicgm. and Erichs. Arcliiv, 1843, p. 69.
DORIS MINUTA, Kocli, Deutsch. Crust., h. xxxv, t. 3, 1841.

The thorax and abdomen are not distinctly separated
from each other. They are composed of ten segments,
which gradually diminish in size as they descend. The
first consolidated with the head, is the largest, and the
last one terminates in two short lobes, from which issue
two long filaments, slightly serrated on their edges. At
the junction of the fifth with the fourth articulation, the
body is very moveable, and the animal frequently turns
up the posterior extremity upon the anterior, in the man-
ner of the kind of beetle called Staphylinus. Jurine has
taken the trivial name of stapltylinm from this circum-
stance, objecting to the name of minutus, by which Miiller
originally designated it, as, he says, we may possibly find
still smaller species. I have, however, retained the name
which Miiller bestowed, as he was the first author who
gave any detailed description of it. The males (t. XXV,
f. 4) are smaller than the females.

206 BRITISH ENTOMOSTRAOA.

The antennae are very short, compared with those of
the two preceding genera. In the female (f. 5 a) they
are composed of nine articulations ; in the male (f. 4 a}
of only seven. Between the fourth and fifth articulations
in both sexes, we see a small lateral ring of one short
joint, and two or three setae.

In the male, both antennas have the swelling and hinge-
joint, the swelling existing chiefly abont the fifth articu-
lation ; all the first five, however, being of greater size
than the corresponding ones in the female. The hinge-
joint is situated near the extremity.

The antennules are simple (t. XXV, f. 5 b], and com-
posed of two articulations. Upon the first is placed a
small shoot, terminated by four setas, while the second is
furnished with seven short spines on its upper edge, and
terminated by four larger ones.

. I urine represents the antennules as of six articulations,
and his figure of these organs differs entirely from mine,
which after frequent and repeated examinations never
varied in their appearance in the least.

The mandibles (f. 5 c] in figure resemble very much
those organs in the C[//cl<i/i* ///"/dr/i-or/iix ; the palpiform
branch springing from the centre, and consisting of three
articulations, terminated by several seta?.

The anterior or first pair of foot -jaws (f. "> r] are com-
posed each of a pretty large, oval body, dividing at the
extremity into four short digitations, of equal length, each
furnished with three seta3. The posterior or second pair
of foot-jaws (f. 5 d) are of very simple organi/ation.
They are formed of three articulations, the last of which
appears to be a very fine hook, forming, with the other
two, an angle always directed forwards towards the mouth.
These hooks appear to stop all molecules of food in their
passage, and, by their constant motion, carry them to the
mandibles.

The feet are live pairs in number, and are much longer
in proportion than in the preceding genus, and dittcr in
some respects from each other. The first pair (f. 5 /')

CANTHOCAMPTUS. 207

has both stalks divided into three articulations, the ex-
ternal having all three of nearly an equal length, whilst
the internal has the first articulation nearly as long as all
the three of the external put together, but the last two
short, and inclined outwards. The three succeeding pairs
(f. 5 y, li) have the internal stalk shorter than the external,
both consisting of three joints, though Jurine says the
external has five. The fourth pair are the longest of all.
The fifth pair (f. 5 i) are small, and rudimentary. They
are situated under the fifth segment, and consist each of
a flat body, from each side of which issues an appendage
furnished with several hairs, the external being the longer,
and giving off" a number of setse also from its external edge.
In the male they have been considered as the organs of
generation.

At the base of the sixth ring in the female are the
openings of the canalis deferens, and under the sixth and
seventh segments the adults of the same sex carry a very
singular, horny-looking, club-shaped organ, which is
fastened to the body by a narrow, elongated stalk. It is
somewhat curved, and directed backwards; its colour
being almost always more or less of a red hue. This organ
is not found in the young female, nor till after she has
several times laid eggs. Its hardness is greater than that
of the shell or carapace of the animal. Jurine has seen
two in one female, one red, the other black. Its use is
unknown.

M. Siebold has conjectured its use to be the same as
that of the elongated tubes occasionally seen in the females
of Diaptomus (see the description of that genus) ; and
asserts that he has seen these bodies suspended over the
genital region of the female, and still inclosed in the
deferent canals of certain males, which by their antennas
were attached to the tail of the female. He never saw
the male, however, fasten this body to the female.

Jurine says that this body is never seen in the female
till after she has several times laid eggs. In my own ex-
perience, I have never seen more than one body attached

208 imiTisn I:\TOMOSTRACA.

to a female, and have never seen an adult without it, as
the female has it constantly attached, though the young
in the ova are ready to be hatched. It is so hard and
horny too, and differs so much in texture and appearance
from the spermatic tubes found in Diaptomus, being too
solid to contain any soft matter, or to form a hollow tube,
that I am much inclined to doubt the accuracy of Siebold's
conjecture, and to believe that the true use of these organs
is still unknown.

In copulation, the male of this species lays hold of the
terminating segment of the abdomen of the female, just
above the commencement of the long filaments which
issue from it.

Hal. — Ponds and ditches of fresh water, all the year
round; common.

2. CANTHOCAMPTUS STROMII. Tab. XXVII, fig. 3, 3 a.

CYCLOPS STROMII, 7_>v;,v/, Mag.Zool.and Bot., i,330,t. 9, f. 23-25, 1837.
CYCLOPS BREVICORNIS, J'xiiril, Trans. Bunv. Xat. Club, i, 97, 1835.
CANTHOCARPUS STROMII, Buird, Trans. BCT\Y. Nat. Club, ii, 15 I, 1 s I ."> .

NAI 1'i.irs STKOMII, /'/////'/-///, \\ ic^iu. and Erichs. Arckiv, 1 sl,'5, p. (\\\.

The thorax and abdomen consist of ten segments,
gradually tapering to the extremity, without any decided
difference between them. The first segment, consolidated
with the head, is the largest, and is furnished with a
conical beak ; the last segment terminates in two lobes,
which give issue to tAvo setae. These are much shorter
than those of the preceding species, being scarcely half
the length of the body.

The antennae are composed of eight short articulations,
and at the junction of the fifth with the sixth they have
a lateral joint. In the male, the swelling and hinge-joint
arc as in the preceding species. Each of the articulations
of the antenna' throws forward one or two short seta'.
The anteunules are formed of two articulations, the
>eeoii(| heing terminated by about four somewhat long
filaments. The mandibles were not seen. The posterior

CANTHOCAMPTUS. 209

foot-jaws consist, as in the preceding species, of two
articulations, and a tolerably strong hook, which points
upwards.

The first pair of feet (t. XXVII, f. 3 a) has the ex-
ternal or superior stalk much smaller and shorter than
the other, and is divided into three joints, the last "of
which is terminated by three rather strong setae, or small
hooks. The internal or inferior stalk is much the longer
of the two, and is composed of tAvo articulations, the first
being very long in proportion to the second, which is ex-
ceedingly short, and terminated by a curved hook. The
three succeeding pairs of feet are precisely similar to
those of C. minntm. The fifth pair is rather larger than
in preceding species, and is formed of a broad, flat body,
which is rounded at one side, and furnished with several
rather long and finely-serrated setse; the opposite side
giving off an appendage, provided likewise with setae
serrated on their edges.

When I first noticed this species, I considered it as the
Cyclops brevicornis of Miiller, who professes to take the
species from Strom, in the ' Acta Hafnise/ * and who,
among other characters, describes it as " setis caudae
brevissimis" Upon referring afterwards, however, to
Strom's paper, and finding his description of it as " setis
caucUe longissimis" I gave it the name of Cyclops Stromii,^
and having since that seen the figure he gives of the
species he describes, I have no doubt of this being quite
distinct.

Hab. — Sea-shore at Cockburnspath, Berwick, &c.,
amongst corallines and seaweeds, 1835. Dover, North
Foreland, September 1849.

* Vol. ix, p. 590.

f Mag. Zool. and Botany, i, 330.

14

210 BRITISH ENTOMOSTRACA.

3. CANTIIOCAMPTUS FURCATUS. Tab. XXV, figs. 1, 2 ;
Tab. XXX, figs. 4, 5, 6.

CYCLOPS FURCATUS, Baird, Mag. Zool. and Bot., i, 330, t. 9, f. 26-28,

1837.

CYCLOPSINA FURCATUS, M. ]-I>l>rt,,-tls, Hist. Nat. Crust., iii, 429.
CANTJIOCARPUS FURCATUS, Baird, Trans. Berw. Nat. Club, ii, 154, 1845.
NAUPLIUS FURCATUS, P/u'lippi, Wiegm.audEricbs. Arcbiv, 1S43, p.69.

The thorax and abdomen are more distinctly separate
from each other than the two preceding species, especially
when viewed in a prone position. They are composed of
ten segments, the first being the largest ; the last termi-
nating in two short lobes, from which issue two long
setae, more than half the length of the body, and two
others, about half the length of the former. The first
segment, with which the head is consolidated, is furnished
with a short beak. The eye is of a bright ruby colour.

The antennas consist of seven or eight articulations, and
at the fourth joint are very distinctly forked. The upper
division is not articulated, and is longer than the lower
limb, which is divided into three or four joints, each of
which throws upwards and forwards a tuft of short setae.
The antenuules are formed of two articulations, the latter
terminating in three or four rather long setae. The man-
dibles were not seen. The posterior foot-jaws consist of
two segments, the latter terminating in a curved hook,
pointing upwards, as in C. mi/niliis.

The first pair of feet (f. 2 a) has the superior or ex-
ternal stalk the longer of the two. It, is composed of two
joints, the first of which is short, and the second longer,
having a strong tooth or process on its inferior edge, and
terminating in three or four short, curved setae or hooks.
The inferior or internal stalk has three articulations; the
first short and thick, the second longer and broad, and
the third short :md terminated by two tolerably long and
st iMi^ht set;e and live or six curved ones, each gradually lie-
coming shorter than the others. The three succeeding pairs
of leii> resemble those of the two preeeding species. The
fifth pair ft. \\\, I'. ') ft] has an appendage in the form of

CANTHOCAMPTUS. 211

a long, slender, slightly-curved stalk, toothed or serrated
on the upper edge, and terminating in three or four hairs.
The external ovary (t. XXX, f. 4 a) is single, large, oval-
shaped, and generally lying across the abdomen, in con-
sequence perhaps of which the animal generally swims
prone or supine, seldom swimming on its lateral surface,
as the other species do. I have met with but few specimens
of this species, all of which were females ; and in two or
three of these there was attached to the dorsal surface of
the fourth segment of the body a substance very much
resembling a polype, consisting of a pedicle and three
branches, each branch terminated by four short fingers.

Hah. — Berwick Bay, 1835 ; not common. Dover,
North Foreland, September 1849 ; rare. Poole, Sept.
1S44, Henry Hyde Salter, Esq.*

4. CANTHOCAMPTUS MINUTICORNIS. Tab. XXV, fig. 3.

CYCLOPS MiNUTicoKNivS, Midler, Entomost., 117, 1. 19, f. 14, 15, 1781.

Latreille, Hist. Nat. Crust., iv, 267.

Bosc, Man. Hist. Nat. Crust., ii, 267.

Saird, Trans. Berw. Nat. Club, i, 97.

MONOCULUS MINUTICOBNIS, Manuel, Enc. rueth., vii, 720, t. 264,

f. 21, 22.

Gmelin, Linn. Syst. Nat., edit. 13th, i,

2998, No. 17.

CYCLOPS INEKMIS, Tilesius, Mem. de 1'Acad. de St. Petersb.,v.t. 8,f.9.
CANTHOCAKPUS MINUTICORNIS, Baird, Trans. Berw. Nat. Club, ii, 154.

The thorax is composed of four segments, each termi-
nating at the back in a sharp spine. The first segment,
comprising, like the other species, the head, is the largest,
and is strongly marked with a large black spot, covering
half of it, and very discernible to the naked eye.

The abdomen consists of five segments, the terminating
one being bilobed, and furnished with a stout seta of about
half the length of the animal. The antennae are divided

* The figures in tab. XXX, of this pretty little species, are from sketches
made by Mr. Salter, at Poole, in September 1844, for which, with some in-
teresting notes, I am indebted to the courtesy of Professor T. Bell, whose
kindness, during the time I have been preparing this monograph, I feel real
pleasure in acknowledging.

'212 BRITISH ENTOMORTRACA.

into cio;ht verv short articulations, having between the

o » o

fourth and fifth a very small lateral joint, as in most of the
other species. Each articulation sends off one or more
seta?. The antennules are similar to these organs in the
other species, as arc also the posterior foot-jaws, which
consist of two rounded joints, terminated by a slightly-
curved book.

The first pah1 of feet docs not differ in structure from the
others, and consists of two stalks, of nearly equal length,
each composed of three articulations, and each articulation
giving off two or three setae. The outer branch is more
slender than the inner. The fulcra or supports consist of
a broad, flat plate, with several tolerably long seta?, as in
the preceding species.

Hah. — Berwick Bay, 1835. Dover, North Foreland,
September 1849.

Genus 3 — ARPACTICUS.*

CYCLOPS, Mi'dlci; Tilesuis, Jiaird, fyc.
MONOCULUS, Manuel, Gmrli/i, $r.
ARPACTICUS, M. AV///Y//V/.V, .Ihiinl, Dana (iu part).
NATJFLIUS (pars), Philippi.

Character. — Foot-jaws forming strong cheliform. hands.
Antennules simple. Ovary single.

]. ARPACTICUS CHELIFER. Tab. XXIX, figs. 2, 3, %a-g.

CYCLOPS CHELIFER, Mirlli-r, 7,ool. Dan. Prod., No. 2-il3, 1776;

KM Inmost., 114, t. 19, f. 1-3.
latreille, Hist. Nat. Crust., iv, 209.
Hose, }lan Hist. .\at. Crust., ii, 259.
Jiairrt. Mag. Zool. and I'-oi, i, 328, t. !>, f. 15-22.

MOHOCI I.I S CHELIFER, Mitilllfl, Kllf. llirtll., \ ii, 721, t. 201, f. 32-3-1.

Omelin, Linn. S\>1. Nat, nlit. 13th, i, 2998,
No. 21.

CYCLOPS Jon s SIMM. /.V//W, Trans. r,rr\v. Nat . Club, i. 97, t. 2, f. 4, 1 VS.', .
CYCLOPS ARM ATI s, '/V/V.svV'.v, .Mi'iii. Acail. Iniji. Si. IVtrrsl)., v, 3(iG,

I. s, f. 7, 8.

ARPACTICI s < nu.n i n. ///'//v/. Trans. Bcnv. Nai. Clul', ii, 15 I. L845.
NA.TTMI s t m.i.m i;, /'////////</, \Vii'i:iii. ami KnVlis. Arcln\ , 18-13, p. 69.

* 1 -•'.,

ARPACTICUS.

213

The thorax consists of four, the abdomen of six seg-
ments, the terminating one giving issue to two long, linear,
finely-serrated setae, fully the length of the body. The
upper or cephalo-thoracic segment, comprising the head,
consolidated with it, is beaked, ha\ing a short conical
elongation in the centre.

The antennae (f. 3 «) are short, of about ten articula-
tions in the female, and at the junction of the fourth with
the fifth there is a small lateral joint in both sexes. At
the fifth ling, in the male, is situated the swelling and
hinge-joint. The antennules (f. 3 b) consist of two arti-
culations, the first having a shoot sent off from about its
centre, divided into two joints, which are furnished with
several hairs ; the second being terminated by five setse,
the three internal of which are the longest, and have a
joint near the middle of their length.

The mandibles (f. 3 c) resemble very much these organs
in the Canthocamptns minutus, the teeth, however, being
more distinctly seen. The posterior foot -jaws (f. 3 e) are
composed of three articulations, the first being long, the
second short and curved, and the third forming a strong
curved hook, the two terminal combined having the ap-
pearance of a strong claw.

The first pair of feet (f. 3/) consists of two unequal
stalks, arising from a common base of considerable length.
The superior is the longer of the two, and is composed of
two nearly equal stalks, serrated on their upper edge, the
second terminating in three short hooks. The inferior
stalk is also formed of two articulations, the first of which
is much the longer of the two, and is serrated, the second
being very short, and terminating in two curved hooks.
The three other pairs of feet (f. 3 g) consist, each stalk, of
three articulations, furnished with long hairs, one or two
of the long terminating ones being finely serrated. The
external stalk is larger and longer than the internal. All
three pairs of feet resemble each other.

The supports or fulcra (f. 3 d] are composed each of a

214 BRITISH ENTOMOSTRACA.

broad, flat body, rounded at one side, and furnished with
several rather long, finely-serrated setae.

The specimens of this species, which I have now referred
to the Cyclops chelifer of M filler, differ in so many points
from his figures and description, that in a paper upon the
Berwickshire Entomostraca, read before the Berwick. Nat.
Club, and since that published in their ' Transactions,'
1 was induced to make a distinct species of it, and named
it Ct/clojJS Johnstoni. Upon more minute examination,
however, I have become satisfied that, notwithstanding
these discrepancies, it approaches sufficiently near the
C. clit'lifcr to be identified with it. In describing this
species, Miiller says there are no articulations in the body,
but that in form it is " farciminis facie." He figures,
too, only three articulations to the antennae. These charac-
ters are so much at variance with the analogous portions
of the body in all the other species of this family, that, as
he mentions it as of rare occurrence, it is most probable
he must have made some mistake with regard to them.
Some differences also exist in his description of the first
pair effect, and the length of the caudal setae ; but they
agree so well in the characteristic foot-jaws, in the beaked
head, and in the general form of the animal, that I have
now no hesitation in referring it to the Cyclops clidifcr of
Miiller.

Hal). — Sea-shore of Berwickshire, Cockburnspath, Ber-
wick Bay, &c. ; common. Dover, North Foreland, Sep-
tember 1849.

2. ARPACTICUS NOBILIS. Tab. XXVIII, figs. 2, 2 a-e.

ARPACTICUS NOIULIS, />,//,->/, Trans. Bcnv. Nat. Club, ii, 155, 1815;

Ann. and Mai;. Nat. Hist., xvii, 410, t. 9,
f. 5, 5 ft, b, c, il.

The thoracic and abdominal portions of the body are

* Tiloius describes his C. armnhix as liavint: Ilir articulations of tin- body
vcr\ iinlMiiirl, ami uses the .same cxpi rssi,,n, "faiviniinis facie;." lit; alludes
to tl\c <'. flulif'-r of Miillcr Jis being a fresh-water species!

ARPACTICUS. 215

distinct from each other. The thorax is composed of four
segments, and is large and rounded. The abdomen con-
sists of six slender segments, the last being bilobed, and
giving off two long setae and two short ones. The whole
animal is beautifully coloured with green, red, and purple.
The eye is large, of a ruby colour.

The antennae (t. XXVIII, f. 2 a) are short, divided into
seven articulations, all of which are setiferous. The first two
are short and stout ; the third is much longer, toothed on
its upper edge, and giving off at its extremity several long
setae. The last four are small and short.

The antennules (f. 2 b) are composed of two seg-
ments, the first giving off a shoot from about the middle
of its length, and the second terminating in several stout
setae.

The mandibles and anterior or first pair of foot-jaws
are strong, and resemble the same organs in Cyclops
quadricornis. The posterior foot-jaws (f. 2 d] are shorter,
but much stouter than those of the preceding species,
and consist, as in them, of the two joints and strong
terminal hooked claw. The thoracic pair of feet (f. 2 e)
differs in structure from the others. It consists of two
stalks, rising from a common base ; the anterior or upper
stalk composed of one long joint and a very short one,
which terminates in a strong claw, the posterior or in-
ferior stalk being very short, toothed on its edge, and
giving off several stout setae. The abdominal feet re-
semble those of preceding species, the setse with which
they and the fulcra are provided being ah1 plumose. The
fulcra (f. 2 c] resemble those of chelifer. The setae of the
caudal segment, however, are not plumose.

This species is at least three times larger than the pre-
ceding, and the body is stouter and more rounded.

Hob. — Along with preceding in Berwick Bay, 1835.
Dover, North Foreland, September 1849.

216 BRITISH l.\T()MOSTKA( A.

4 — ALTEI TII \. :

CYCLOPS, Eaird, Mag. Zool. and Bot., i, 1837.
ALTEVTHA, Baird, Trans. Bcnv. Nat. Club, ii, 155, 1845 ;
Ann. and Mag. Nat. Hist., xvii, 416.

Character. — Foot-jaws small, simple ; body flat. Two
strong falciform appendages from the tifth segment of the
body.

1. ALTEUTHA DEPRESSA. Tab. XXX, figs. 1, 2.

CYCLOPS DEPRESSES, Buii-il, Mag. Zool. and Bot., 331, t. 10, f. 9-12,

1837.

ALTECTHA DEPRESSA, JJainI, Trans. Bcrw. Nat. Chili, ii, 155, 1S45 ;

Ann. and Mag. Nat, Hist., xvii, 416.

The body is depressed, flat, and broad, differing in this
respect very much from all the other genera described.

The thorax is composed of four segments, the first of
which contains the head consolidated with it, and is much
the largest, being more than equal to the three succeeding,
and having the upper part projecting in a short obtuse
point.

The abdomen consists of five segments, and is about
one third the length of the bodv : the terminating seg-

O «/ ' O O

nient having on each side a small lobe, from each of which
issues a moderately long seta.

The eye is situated rather lower down than usual in the
other species of this family, and is of a fine ruby colour.

The antenn;e are short, strong, subcylindrical, setiferous,
and divided into six or se\en articulations; the first three
of which an; the largest, the last lour being smaller and
shorter. In the female we find a lateral ring at the junc-
tion of the fourth and fifth joints. The swelling, in the
male, is situated in the fourth, followed by the hinge-joint,
and terminated by a hook. The antennules are of two
articulations, the latter being terminated by four short

* "Alteutha/1 tl»- Tovm of the Tweed

ALTEUTHA. 217

setae. From the opaqueness of the body, and the flatness
of its form, I could not distinctly perceive the mandibles
or foot-jaws ; except that the latter were like the corre-
sponding organs in the Canthocaniptus. The first pair of
feet (t. XXX, f. 1 a) is composed of two stalks rising from
one common base, each stalk consisting of three joints.
The superior or external stalk is longer than the inferior,
the last joint terminating in four short hooks. The in-
ferior stalk terminates in several short setae, and has a long
filament at each joint. The other legs are of the same
form and structure as in the preceding genera, and pro-
vided with numerous long hairs.

At the junction of the first with the second segment of
the abdomen, there issues on each side an organ (f. 1 <5), very
much resembling the fulcra or supports we find occurring
at the same part of the body in the other genera already
described, only that in this little creature we observe the
same sort of organ in the male as well as in the female.
It consists of a broad, falciform plate, which terminates in
a tolerably long, bluntish, hollow spine, having four short
teeth or hollow spines (in the male) on the outer edge,
the whole organ being nearly equal in length to the
abdomen. In the female these organs are not quite so
large as in the male, and have only two short teeth on the
outer edge, both of which are situated near the base. In
the female also, the second segment of the abdomen is
much larger than in the male. The posterior two thirds
of the thoracic segment is marked with a broad fascia of
a very dark colour, with a ruby tinge in it. The two
upper segments of the abdomen are marked in the same
manner, but not of so deep a hue.

The ovary is single, large, round, lying right across the
abdomen.

The motion of this little creature is very peculiar. It
generally swims on its back, and instead of darting/or-
ivard through the water, as the other species of this family
do, it springs with a bound from the bottom of the vessel,
where it rests when undisturbed, up to the surf ace of the

218 BRITISH ENTOMOSTRACA.

Avater. For this purpose it curls its body into the form
of a ball, and then suddenly returning to the straight
position, springs Avith a sudden bound from the bottom
to the surface, falling gradually doAvn again to the same
place from which it had sprung.

Hab. — Berwick Bay, 1835, not common.

Family 2— DIAPTOMIM.

'. — Head in general distinguishable from the
body, though firmly articulated with the first ring of the
thorax. Eoot-jaAvs, three pairs, Avcll developed. Legs,
five pairs ; the last pair differing in structure from the
others, and differing also from each other in the tAA'o sexes.
One eye; sometimes in male sex pedunculated. Right
antennae alone, in the male, furnished Avith the SAVollen
hinge-joint.

The habits and manners of the animals of this family
are very similar to those of the Cyclopidae. Some are
inhabitants of the fresh water, and others arc marine.
The manner of hatching their young, and the changes

O «/ O7 O

these undergo in their progress to maturity, are very
similar; only it would appear, from Jurine's observations,
that the mother must carry the ova along Avith her, till the
young arc hatched, whilst, in the Cyclopida3, the eggs may
be hatched, after they are removed from the mother.

This family contains three British genera.

1. DIAPTOMIS. — Head distinguishable from body.
Thorax and abdomen each composed of five segments.
Antcnnules two-branched.

2. TI.MOKA. — Head consolidated Avith first ring of
thorax. Thorax composed of five, and abdomen of three
segments. Antenuulcs two-branched.

3. ANOMALOCKKA. — Head distinguishable from body.
Thorax composed of six, abdomen of four segments.
Antcnnules not two-branched.

DIAPTOMUS. 219

Genus I — DIAPTOMUS. *

MONOCULUS, LitttHKMs, Fabwiits, Jurine, fyc.
CYCLOPS, MiUler, Desmarcst, Manuel, $-c.

DIAPTOMCS, /. 0. Westwood, Partingtou's Cyclopsed. Nat. Hist.,
art. Cyclops, 183G ; Entomologist's Text-Book, 183 8.
OMETHIA. Templeton, Trans. Ent. Soc., ii, 118, 1838.
CYCLOPSINA,! M. Edtcards, 1840.

Pliilifpi, Wiegm. and Erichs. Archiv, 1843.
— Baird, Zoologist, i, 56 ; Trans. Berw. Nat. Club, ii,154.
Dana, Proc. Amer. Acad. Sc., 1847.

Character. — Head distinguishable from body, though
firmly articulated with the first ring of thorax. Thorax
and abdomen, each of five segments. Antennules com-
posed of two branches. Foot-jaws not branched. Legs
five pairs ; the first pair having one branch of three arti-
culations, and the other of two ; the three succeeding
pairs having each a branch of three joints. External ovary
large, single, and lying across the abdomen.

1. DJAPTOMUS CASTOR. Tab. XXVI, figs. 1, 2, 2 a-j.

MONOCULUS CASTOK, Jurine, Hist. Nat. Monoc., 50-73, t. 4-6, 1820.
CYCLOPS CASTOK, Desmarest, Cons, gen., 363, t. 53, f. 5, 1825.

Baird, Mag. Zool. and Bot., 324, t. 10, f. 1-8.
CYCLOPS OEBULEUS, Matter, Zool. Dan. Prod., No. 2411, 1776 ;

Entomost., 102, t. 15, f. 1-9.
Latreille, Hist. Nat. Crust., iv, 265.
Bosc, Man. Hist. Nat. Crust., ii, 257.

MONOCULUS C^RULEUS, Fubricius, System. Eutomolog., 295.

Manuel, Enc. meth., t. 264, f. 1-9.
Gmel'm, Linn. Syst. Nat., 2997, No. 12,
edit. 13th.

* From f t«, through ; and nrra^ai, to fly.

+ Though the genus Cyclopsinn has been adopted from M. Edwards by
Philippi, and heretofore by myself, yet as its founder includes other species
belonging to the family in it which, as I have shown above (p. 204), cannot
be received, and as Mr. Westwood, four years previous to the publication
of M. Edwards's work, distinctly defined the genus Diaptomus, I now, obeying
the law of priority, assume his name ; and, indeed, while Mr. Westwood's
paper in which he founded the genus was still in MS. I had already indicated
his name for it in the 'Trans. Berw. Nat. Club' for 1835.

220 BRITISH ENTO.MOSTRACA.

CYCLOPS L.UIM/LAITS, Mn/lcf, Zool. Dau. Trod., No. 2410, 17/6;

Kutomost. 105, t. 16, f. 4-6.
AV/W,,//,-, Brvt. zurNaturg., 7-9, t. 2, f. 4-12.
J,<'/,rilf?, Hist. Nat. Crust., iv, 266.
Bosc, Mail. Hist. Nut. Crust., ii, 258.
AV//Y/, Trans. Berw. Nat. Club, i, 97.

MONOCVLI'S LAC1M I.VM 8, Manuel, EuC. llli'tll., (. 2l.i !•, I'. 15-17.

i;Hielia, Liuu. Syst. Nat., 29<J7, No. 14.
CYCLOPS KVBEXS, .l//'V/,v, Entomost., 104, t. 16, f. 1-3, 1781.
Latreille, Hist. Nat. Crust,, iv, 266.
Bote, Man. Hist. Nat. Crust., ii, 25S.
/.W/v/, Trans. Berw. Nat. Club, i, 97, t. 2, f. 2 (the
young).

MHM.K.I l.t s Kl BENS, /','//, 7, vV'.v, Op. Clt.

/, Hue. mi'th., t. L'GI, f. 10, 11.
lui, Liuii. Syst. Nat., i, 2'.»'.i7, No. 13.
CASTOK, 11'i-x/riMJ, Partington's Cyclop. Nat, Hist., art.

Cyclops, 1836.

CASTOR Baird (////^///Vi, Trans. IVnv. Nat. Club, i, 97,
1835; Philosophical Transactions, No. 288j
1703, f. G of accompanying plate.
Bukt',; Microsc. made Easy, 93, t. 9, f. 2.

CYCLOPSIXA CASTOK, M. Eilc-ards, Hist. Nat. Crust., iii, i27, 1S40.
/;,///•'/, Trans. Bcrw. Nat, Club, ii, 154, lMr>.
(ii..\r< EA KCBKNS, Koc//, Dcutsch. Crust., h. xxxv, t. 4 (male), t. 5

(female).
GLAUCEA C.ERULEA, Koch, 1. c., xxxv, t. 6.

Tlic head may be easily distinguished
from the body, though it is firmly articulated with the
first segment of the thorax.

The thorax consists of five rings, the first being consi-
derably the largest.

The abdomen is composed of five articulations also, tin-
last being divided at extremity into two lobes, each of
which gives origin to five plumose seta-.

The eye is large, of a fine ruby colour ; and we can
distinctly see the muscles which move it, and of which
there are several.

The antenna- are large organs, of great length, and
strong. They an- formed of aliout twenty-six articulations,
each furnished with one or more set;e, the last terminated

DIAPTOMUS. 221

by five of different lengths. In the male, the right an-
tenna alone has the swelling and hinge-joint, which cha-
racterise the sex. This joint is formed in the same manner
as that in the Cyclopidae.

'Hie antennnles (t. XXVI, f. 2 a) are of considerable size,
and bifid ; two branches of unequal length, arising from a
common footstalk. The shorter of the two can be moved
backwards or forwards at the pleasure of the animal, and
consists of six articulations, the first of which is stout, and
inserted into the common footstalk, and has four stout
setae springing from its edge. The second, third, fourth,
and fifth are very short, and each is furnished on its edge
with a stout seta ; while the last is of considerable length
and is provided at its extremity with three long setae.
The longer branch is composed of three joints. The first
is articulated with the body of the animal, and the third
terminates in several long filaments, which have a joint in
the middle of their length, adding much to their supple-
ness. These organs the little creature puts into rapid
action, and so causes a regular whirlpool in the water,
which attracts every object into its centre, and guides
them into its mouth.

The labrum or lips consist of two small, somewhat
foliated-looking bodies, almost transparent, which, when
any object fit for food passes into the mouth, are seen to
separate from each other and open a passage for it.

The mandibles (f. 2 5} resemble those of the Cyclops
(already described), but have the palpiform branch much
larger and bifid.

The neck terminates in a horny acute point, under
which are six small teeth on the same plane.

The foot-jaws are three pairs in number. The anterior
or first pair (f. 2 c, d] consists of a broad, heart-shaped
plate, with a smaller one of the same form attached to its
upper edge, both having numerous setae springing from
them, in the larger consisting of four on one side, and
eight on the other ; while a third, or smaller plate, bifid,
and equally beset with a number of hairs, springs from

222 MKIT1SH I.NTOMOSTRACA.

(lie upper edge of the centre plate. The second pair
(f. 2 c) is flat and stout, composed each of a body which is
indistinctly divided into three segments. The anterior
edge is prominently marked \vitli several eminences,
from each of which spring two rather long setae, directed
towards the month. The posterior or third pair of foot-
jaws (f. 2/) is much larger than the preceding, and is
formed of seven rings, the first two of which are large in
proportion to the other live.

The legs are five pairs in number, and the first four, as
in the Cyclopidie, are double. The basal portion consists
of two articulations. In the first pair (f. 2y) the external
branch consists of three joints, and the internal of two.
In the three succeeding pairs (f. 2 //) each of the branches
is composed of three segments, and all are furnished with
plumose seta?. The fifth pair is differently formed from
the others, and is strong and well-developed compared
with that of the Cydopidse. They differ also from
each other in the two sexes. Those of the male (f. 2 i)
are almost cylindrical, and consist of two unequal branches
arising from a common footstalk. The right branch is
much the larger of the two, and is formed of three articu-
lations, the last of which is terminated by a long and
strong hook. The left has four rings, and is terminated
by two short spines. This pair of legs is erroneously con-
sidered by Jurine to be the sexual organs; the shorter of
the two branches containing, he believes, the organ itself.
In the female (f. 2 /') the right branch is very much the
larger of the t\vo, and consists of three joints, the last of
which is terminated by a strong curved claw. The left
branch is very slender, composed of only one joint, and a
terminal spine. These organs in the female arc called.
by Jurine, the "fulcra, or supports of the external ovary."

The dorsal vessel, or heart, is verv distinctly to be seen
under the second and third segment of the body. It is
oval, and gi\es origin to two vessels of equal si/e, one
going to the head, and the other to the abdomen, and has
another organ attached to it, which is called by Jurine

DIAPTOMUS. 223

the auricle. The pulsations of the heart are very frequent,
from 112 to 120 in the minute. Underneath the first
segment of the abdomen in the female, is the vulva, or
external organ. It forms also the opening of the canalis
deferens, and through it the ova pass into the external
ovaries. Above this opening we see a triangular, reddish
body, which Jurine calls the opercidum vulvte.

In some specimens of this species, we occasionally see
on each side of the abdomen two, four, or six elongated
bodies, the direction of which is invariably backwards.
In the females, to which sex they are principally confined,
they are found adhering round the operculum vulvas, and
when they have been noticed in the male, they have been
seen adhering to the base of the posterior feet. These
bodies were noticed by Miiller, and are called by him the
lacinifs. He regarded them as some particular organs
belonging to the animal, and they were considered by him
as sufficient to constitute the individual possessing them
into a distinct species, which he describes under the name
of Cyclops latimdatus. The use of these organs, how-
ever, he was totally ignorant of. Jurine also observed
them, and says, that at first he was disposed, like Miiller,
to regard them as peculiar organs, and that from their
presence he was led to infer that the individuals charged
with them were a distinct species. After very attentive
observation, however, he found the number to be irre-
gular ; he found them also occasionally in males, and he
observed that they would separate spontaneously from the
body of the animal. Not being able to discover any use
for them, he conjectured them to be infusory animalcules.
Jurine states, that it is in the months of March and April
that these bodies are to be met with ; but the only time I
have ever seen a specimen of Diaptomus with them at-
tached, was in the month of October. It was taken from
Yetholm Loch, in Roxburghshire ; but an accident occur-
ring to the vessel in which it was placed, I was prevented
from making any lengthened observations upon them.

I'.KI I IMl KNTOMOSTHACA.

M. Siebold, : however, has liad opportunities of studying
them caivfullv, and the results of his observations, with

\j *

bis remarks on the method of copulation of Diaptomus,
are so interesting and striking, that I will give them here
at some length. The male having only the right antenna
provided with the swelling and hinge-joint, seizes hold of
the tail of the female with it, and grasping it tightly,
curves himself up to her ventral surface. He then sur-
rounds the base of her tail with the large hook of his lil'th
pair of feet. The female is at first restless, but she soon
becomes more tranquil, and in this position they both fall
to the bottom of the water, remaining fixed sometimes for
hours together. The act of copulation itself, however,
lasts only for a short time; but what takes place during
that short interval is very remarkable. " A cylindrical
tube, filled with a spermatic liquor, escapes from the sexual
organ of the male, immediately after the connection takes
place ; the male seizes this tube as soon as it has made its
exit, and fastens it against the abdomen of the female, be-
neath the vulva. "f The fifth pair of feet is most probably
the organ by which the male seizes the tube ; but Siebold
did not distinctly ascertain the fact. When it escapes
from the male organ, it is by its rounded extremity ; and
it would appear, that when the animal lays hold of it, he
presses the neck of the tube with the tip of his foot against
the first joint of the tail of the female, and as the neck of
the tube contains a glutinous substance, it immediately
adheres.

Such is the operation, as described by Siebold from
personal observation, and from which he concludes, that it
is with the matter in these tubes that the female is fe-
cundated. No female, he says, possesses a tube before
copulation ; but immediately after the act i< accomplished
\\e sec; one fastened to her, near the vulva. If a male
lie examined, when in heat and before copulation take

M-'in. dc 1:> 800. ilr- Si nilainir.s do l;i Nature, tie Dam/ii:. iii, purl ii,
L839; Ann V,l . .',1 SI r., UV, 26-38, IS tO.

r \nii. dea s''. Vii . \i\. JV

DIAPTOMUS. 225

place, a body like one of these tubes may always be seen
concealed in the sexual parts ; but immediately after
copulation has taken place, nothing of the kind can be
observed in a state of development. Jurine, as I have
observed above, had occasionally seen them in the male,
attached to the base of the posterior feet ; and Siebold
states, that once, upon separating a pair in the act of
copulation, he found a seminal tube attached to the end
of the last pair of feet of the male, " apparently," he says,
"before he had had time to rid himself of the body."

It has been observed, that the males of this species are
very lustful, and they have been seen to attack in succes-
sion several females, some of them even such as had had
connection immediately previous with other males, or that
had external ovaries suspended from their abdomen, so
that it is not uncommon to find two, three, four, and even
five of these tubes in the same female. These tubes are
all similar in size, form, and contents. They are straight,
and scarce extend in length beyond the point of the tail.
They are composed of a colourless, solid envelope, which
is rounded at its inferior free extremity, and terminates at
its upper end in a short, narrow neck, provided with an
opening. Each tube contains three different kinds of
matter : one is white and thick, of a glutinous nature, ex-
tending the whole length of the tube, and is coagulable in
water ; the second consists of a great number of very small,
oval, well-formed bodies, which Siebold considers the real
zoosperins of the animal ; while the third is composed of
a mass of oval bodies of a similar size, and composed of
very fine granules. This latter granular portion of matter
occupies the inferior half of the capsule ; the second portion
lies in the upper half, while the neck only is filled with the
first kind, or the glutinous substance. As soon as the
tube quits the sexual organ of the male, the relative situa-
tion of these substances changes. Immediately it comes
in contact with the water, the third or granular mass
swells, the little oval, granular bodies become round, swell
more and more, till at last they expel the first or .glutinous

15

15151 I IMI 1ATOMOSTK U \

mass which is lodged in the neck, and take its place.
When the glutinous mass is expelled, this granular sub-
stance continues to swell still more, till at last it expels till-
second substance, or the zoosperms, also. As soon as the
glutinous matter touches the water, it coagulates, and a>
it continues to flow out, it leaves a canal in the centre of
tlu; part already expelled and coagulated, which gradually
becomes lengthened and somewhat undulated. When all
the glutinous matter has escaped, the zoosperms follow im-
mediately, and pass through the canal in the coagulated
part, so that by the time they reach the end of this sort of
canal, they are close to the vulva.

"From all this," says Siebold,* "it appear.-, — 1st. Thai
the male does not accomplish a true coition. 2 dry. Me
attaches to the female, during copulation, a tube tilled with
spermatic liquor. 3d. This spermatic tube contains, be-
side the zoosperms, two substances, of which one (tli.
expulsive matter) swells by the influence of the water, and
chases out the whole contents of the tube. The other
substance (the glutinous matter) coagulates in tin- water,
leaving in the middle of the mass a canal, by which the
/oosperms arrive at the vulva. 4th. The zoosperms, situated
in tin- neighbourhood of the vulva, penetrate in a manner
as yet unknown beneath the operculum vulva4, and pro-
bably in this manner fecundate the eggs, which some time
later quit the sexual opening of the female. r>th. One
and the same female is often covered with spermatic tubes
at short intervals by diH'ereut males. (Hit. One and the
same male appears able to furnish more than one single1
tube from its single sexual organ."

These observations of M . Siebold are \ery curious and
highlv interesting; they appear to ha\e been made with
much care : but I am not aware of their having ever been
confirmed by any succeeding naturalist.

.lurinc distinctly and with truth asserts, thai the tlnv<
\\hicli Muller makes, the ('//<•/(>/>* candeua, /•///"•//*.

l,u. :;/"

TEMORA. 227

and ladnulatus, are mere varieties of one species. This,
from the resemblance he fancied he saw in the abdomen
of the female, when loaded with eggs, to the tail of a
beaver, he has named Monoculus Castor. The caruleus
and rubc/is only differ in colour, and the lacinulatus, as
shown above, is merely a female charged with spermatic
tubes. I have not met with any individuals of a bine
colour, all that I have ever examined in this country being
either of a transparent hue or of a delicate red. It is a
very beautiful species, and is the most elegant of any of
this section : cc Son port," writes Jurine, " est elegant ;
sa maniere de s'elancer dans la liquide est noble et harclie ;
ses mouvements sont libres et faciles ; tout enfin annonce
chez lui une superiorite qui caracterise la grandeur de
1'espece a laquelle il appartient."*
This animal is about 1^ line long.

Hab. — In ponds and slow-running water. Common
in the neighbourhood of London, &c., especially in spring
and autumn.

Genus 2

MONOCULUS, Gunner, Fabricius, Manuel, Gnielin.

CYCLOPS, Mutter, Latreille, Lamarck, Bosc, Leach, Edin. Euc.

CALANTJS, Leach, Diet. Sc. Nat.

Templeton, Trans. Ent. Soc., ii.

Character. — Head consolidated with first segment of
thorax. Thorax composed of five, abdomen of three seg-
ments. Antenuules two-branched. Legs five pairs, the
first four having each a branch of two articulations only.

; Hist. Monoc.
f "Temora," the palace of the ancient kings of Ireland.

00 x 1M! I'll Ml F.XTOAlOSTRAi \

1. TKMOUA FI\M MKIIICA. Tab. XXVIII, tigs. 1, 1 «-</.

MUM >( TI.IV FINM LBCHICUS, Gunner, Act. Hafh.,x, 175, f. 20-23, 1765.

('•u I.- IPS FINMAKI :m i >. Mi'ller, Zool. Dun. Prod., No. 2-il5.
CYCLOPS LOXGICOKNIS, .I//'///-/-, Entomost., 115, t. 19, f. 7-'1
• — i l.ciiHii-rl,-. An. B. Vert., v, 189.

l.,itr,-ill<>, Hist. Nat. Crust,, iii, 20<J •. '

Crust, ct Insect., ii, 26.
Bosc, Man. .HIM. Nat. Crust., ii, 259.
Leurli, Kdiub. Enc., art. CrustaceoloL.
MM\,K i i.i > LONGICOENISj Kilti-ii-inx, Ellt. Sjst., ii, 501, No. 52.

Q I'll,,, Linn. Syst. Nat., 2997, No. !•>
Nanm-1, Kuc. nu'lli., 7-'i', fc. 264, f. 11-H

('\i.\\i v |''INM\|{( EHANUSj I.Kti'Ji, Diet. Sc. \;i(., xiv, art. Entoim^t

Desmarest, Cons. gen. Crust.. .'Id I.

i's Voyage, Atlas, t. -J-J. I'. 1 1.

). — The body is of a dark brown colour
(|>IVMT\('<| in spirits).

Thorax consists of five segments ; the first, with which
the head is consolidated, is the largest, the other four
gradually becoming smaller as they descend.

The abdomen has only three segments, and has a long,
bifid, caudal joint, terminated by two short, stout sehe,
serrated on the edges.

The antennae or rami (t. \\V1II, f. I/) are very long.
exceeding the body in length, though not quite equal to
the body and abdomen together, and are composed of
twenty-four short articulations.

The antenmiles (f. 1 //) are two-branched. The
first branch consists of two joints, the latter of which
is deeply notched at the extremity, and is terminated by
seven or eight long hairs. The second branch has .xj\
articulations, the first and last of which are of equal length.
and the four interxening ones are very short. The tirst
joint irivcs oil' from its inner edge four long set;e, each of
the short ones gives off One, and the last is terminated by
two or three of still greater length.

The mandible and its palpilbrm branch (f. 1 a] arc1

AXO.MAIAM'KKA. ~i

\\ell developed, and, as well as the three pairs of foot-jaws
({'. 1 6, (/, c), exactly resemble those of Diaptomus.

The four anterior pairs of %feet' (f. 1 y) are all alike,
and consist of a basal stalk of two articulations, and two
branches of unequal size. The inner branch is much
the smaller, but both are divided into two joints. The
posterior or fifth pair is almost exactly similar to the
corresponding pair in Diaptomus.

I have never found this species alive, having only seen
it preserved in spirits.

Hab. — Coast of Ireland, W. Thompson, Esq.

Genus 3 — ANOMALOCERA.*

ANOMALOCERA, Templeton, Trans. Eut. Soc., ii, 35, 1837.
JEEN.EUS, Goodsir, Edin. New Phil. Jourii., xxxv, 339, 1843.
PONTIA, Bainl, Traus. Berw. Nat. Club, ii, 156.

Character. — Head distinguishable from body; furnished
with a beak, which is divided at apex into two sharp
points, and at the base terminates on either side in a sharp
hooked spine. Thorax divided into six, abdomen into
four segments. Antennules not two-branched. Foot-
jaws strongly developed. Eye in male pedunculated.

1. ANOMALOCERA PATERSONII. Tab. XXVII, figs. 1 a-i ;
2 a-c.

ANOMALOCERA PATERSOHII, Templeton, Traus. Eut. Soc., ii, 35, t. 5,

f. 1-3.

PONTIA PATERSONII, Baird, Trans. Benv. Nat. Club, ii, 156.
IKEN.EUS SPLENDIDUS, Goodsir, Ediu. New Phil. Journ., xxxv, 339,

t. 6, f. 12-17, t. 1, f. 1-9.

Description. — The head is distinguishable from the
body, but firmly articulated with the first segment of the
thorax. It is of a sub -triangular shape, with a curved,

* From ai/w|u«Xoi', dissimilar; and Ktpa^, a horn.

I.HITISI1 KNTOMOSTK M \.

sharp-pointed beak (t. XXVII, f. \gj; f. :2 «, 0) and has

near its junction with the first thoracic ring, on each side,
a short, curved, sharp spine.

The eye is single, in the male fixed upon a short peduncle
(f. 1 g\ and projecting forwards and slightly downwards ;
in the female sessile. " It is of a beautiful dark-brown
colour, with a shade of purple; a circular space at the
extremity is colourless, and sparkles brilliantly."

The thorax is elongated, and consists of six segments,
the last of which is narrower than the others, truncated,
and terminates on each side in a point. Antenna.' King,
about two thirds the length of the whole body. They
are composed of numerous articulations, about twenty-five
in number, each provided with one or more short seta\
In the male the right antenna alone is provided with the
swelling and hinge-joint. The swollen part is particularly
large, and club-shaped, " and running up through the
centre of the swelling may be seen a muscle, which goes
to be attached to the hinge -joint, "f

The antemmlcs (f. 1 a) consist of a single branch,
which is divided into three joints, the terminal joint
1 icing broad, and furnished with several long seta'.
The basal joint sends off from its internal side a small,
slender twig, which is provided at the extremity with three
or four set;e. The labrum or lip is well developed, and
consists of a projecting semi-oval plate, and two lateral
lobes of considerable size.

The mandible (f. 1 li) is in form of a strong plate, fur-
nished with live stout teeth on its internal extremity, and
having a rather large, pal pi form branch from its upper
edge, divided into two smaller branches. Each of these
is formed of t\vo articulations, the terminal one giving off
at its extremity several long, plumose seta-. The jaws
an- only rudimentary organs.

The' foot-jaws are three pairs in number. The first

* ( loc. <-it., ".:'.'.' "Tin' pr.limrlc "I'tlir eye i> «')';> <l;irk blue."—

n, (jinili'il li\ Trm|>lr!on. Inc. cit.

ANOMALOCEKA. 231

pair (f. 1 f) is of moderate si/e, each composed of a
sloul basilar joint or plate, which at its extremity gives
oif two or three other flat joints or plates, all of which
are provided with several long setae. The second pair
(f. 1 d] is larger, formed of a tolerably strong basilar
joint, wliich is lobed at its extremity, and a slender branch
of five articulations. The lobes of the basilar joint, and
the articulations of the slender branch, are all provided
with several plumose seta? of considerable length. The
third pair (f. 1 c) is large, and strongly developed, and
consists of two stout joints, which have on the inner edge
several lobes, furnished with very long, plumose setae,
directed forwards and upwards, so as to meet with the
plumose setae of the antennules.

The feet are five pairs in number. The first four
pairs (f. 1 Jt} are all alike, and formed for swimming.
They consist of a common joint at the base, divided into
two articulations, and two longer stalks. The internal
stalk is divided into two joints, and the external, which
is the larger of the two, into three, all furnished with
numerous setae. The fifth pair is different from the
others, and from each other in the different sexes. In
the female (f. 2 c] it is small, formed of a basilar joint
of two articulations, and a smaller and more slender
joint, of three articulations. At the base of the second
basilar joint, on the inner side, a small, short branch
springs, formed of one articulation. In the male, this
pair of feet (f. 1 i] is large, composed of two stalks, both
of wliich appear to spring from the body without a com-
mon foot-stalk. The one is simple, consisting of three
large joints, which terminate in two or three slender,
styliform setae, while the other is terminated by a strong
claw, or prehensile hand.

The abdomen consists of four segments, the last of
which gives off two caudal lamellae of considerable length,
rach provided with five rather short and plumose setae.
These bodies seem adapted for assisting the animal in
H- Length of animal about three lines.

:J:5:2 KIUTIMI KNTOMOSTHAC \.

From a careful examination of specimen> sent me by
Mr. Thompson, <& Anomcdocera Pafcrxwiii from Ireland.
and fri'i/fi't'x *j)/r,nH<l//x from Scotland, from an exami-
nation of the specimens of Irenes m sent by Mr. Goodsir
himself to the British Museum, and from the figures of
the two given by Mr. Templeton and Mr. Goodsir, I have
no doubt they arc identically the same. The tubular
organ in which the eye is situated in Irena?us, and which
forms, according to Mr. Goodsir, the chief generic cha-
racter, is merely the peduncle upon which the eye is
placed, and which is well described in Anomalocera, by
Mr. Templeton. Mr. Goodsir's description of Irenaens
seems to have been taken from a male specimen. He
describes the little animal, when alive, as of a \rry bril-
liant appearance. "The whole animal," he says, " gives
forth a kind of luminous appearance, which is apparently
caused by the splendid metallic colours with which it is
adorned. The prevailing colours are sapphirinc and
emerald."

" The colour of the animal," says Mr. Paterson, as
quoted by Mr. Templeton, " is a bright green, mottled
with darker shading* ; the green colour is very fugacious,
and observable only in recent specimens .... The tir>i
time," he continues, " on which 1 took any of these, was
in crossing the ferry at the mouth of Lame Lough,
county Antrim, in the evening of the 2d of May. They
were so numerous, that in the space of fifteen minutes
above three hundred were taken. Though kept in a
glass jar of sea-water they all died during the night, and
were almost colourless next morning .... They swim
with a livelv and constant motion, and jerk themselves

i/ «i

out of the way when pursued. They form a portion of
the food of a tentaculated Beroc." (pp. 39, 40.)

j. — Mouth of Larnc Lough, county of Antrim,
Mr. Templeton, \V. Thompson, Ks<j. (.l/inm/i/urcrtt} ;
l;rithof Forth, Mr. d.udsir: l\v les of Bute, AV. Thompson,
Ks<|. (lrf,t,rnx} ; llrit. Mus.

CETOCHILUS.

233

Family :i— CETOCHILIDJE*

PONTIENS, J/. Edwards, Hist. Nat. Crust., iii, '112.
PONTIAD/E, Baird, Trans. Berw. Nat. Club, ii, 155.

Character. — Plead distinguishable from body, but firmly
articulated with the first ring of thorax. Foot-jaws three
pairs, strongly developed. Legs five pairs. Eyes two
in number. Right antennae alone, in male, furnished
with the swollen hinge-joint.

The individuals hitherto discovered belonging to this
family are not numerous. The only British genus yet
noticed is the enus Cetochilus.

Genus CETOCHILUS. f

Roussel de Vauzeme, Ann. des Sc. Nat., 2d series, i, 333.
J/. Edwards, Hist. Nat. Crust., iii, 421.
Goodsir, Ediri. New Phil. Jouru., xxxv, 339.
, Trans. Berw. Nat. Club, ii, 150.

Character. — Head furnished with two small, styliform
prolongations. Anteunules of two branches, of nearly
equal size. Foot-jaws not branched. Thorax of six,
abdomen of four segments. Last pair of feet of the same
formation as the others.

This genus was established by Roussel de Vauzeme,
in the ' Ann. des Sc. Nat.,' second series, i, 1834 ; and he
there gives a very interesting account of its use, as con-
stituting, in a great measure, the food of the whale.
Vauzeme was attached to a vessel employed in the whale
fishery in the Southern Ocean ; and for four months the
crew were engaged in the neighbourhood of the island of

* The term Pontia having been preoccupied by a genus of Lepidoptera,
it may become necessary to alter the name of M. Edwards's genus of this
family. Mr. Dana, indeed, has done so, changing it to Pontella. I have
therefore used the term Cetochilid/e as not liable to any objection, and the
more especially as the genus Cetochilus is the only one of the family found
in Britain as yet.

f From (fj/roc, a whale ; and xiXoc, food.

HK1TIMI l.NTo.Mo.sTU.U'A.

Tristan d'Acunha, in the South Atlantic, without his CUT

ha\ing been able to observe what formed the food of the
whale-. Leaving that quarter, ho\vever, at the end of
that time, and steering for Cape Horn, he one morning,
in the month of February, observed the surfaee of the sea
streaked with red lines, of several miles in extent, and
giving the appearance of blood to the water. The ex-
perienced sailors on board immediately announced that
they had now reached the yjW/>/r of the whales.
Accordingly, they very soon afterwards saw them sport-
ing about in the midst of these ruddy banks. Upon
examining the water thus coloured, Vauzeme found it
caused by an immense number of small Crustaceans,
which were of a red hue. They swarmed in myriads
on the surface of the sea, and, when the wind was bois-
terous, a whole bank of them would be taken up by a
wave, and carried on board the vessel, covering the deck,
and the clothes of the sailors. The whales swallowed
them in myriads, and they served for food not only
to them, but to the Cirrhopodes (the Coronulee and
Tubicinelhe), which live as parasites upon their skin.
The American Ushers on that station informed him that
these little creatures, in the tine weather of October and
November, remain concealed deep under the water, but
that after that time, they come to the surface io lay their
eggs. In our own seas, this same kind of Crustacean has
also been observed to be the food of cetaceous animals.

In the IVith of Forth, Mr. Goods ir informs us,* that
during the summer months, great masses of animal matter
abound on the surface of the sea, and that this had long
been noticed by the fishermen on the coast, and was called
by them maidre. I'pon examining this matter, in the
neighbourhood of the Isle of May, lie found it to consist
of Cirrhopodes, Crustaceans, and Acalcpha ; but thai of

all these, I he Kntoinosl racoiis Crustaceans abounded in
the greatest quantity, " or rather masses," he observes

c\\ i ' 1 1 1 1

CETOCHILUS. 235

" for it gives a faint idea, to speak of numbers .... On
looking into the water," he continues, " it was found to
be quite obscured by the moving masses of Entomostraca,
which rendered it impossible to see anything even a few
inches below the surface. But if a clear spot is obtained,
so as to allow the observer to get a view of the bottom,
immense shoals of cod-fish are seen swimming lazily
about, and devouring their minute prey in great quan-
tities. Occasionally small shoals of herrings are seen,
pursuing them with greater agility .... Great numbers
of Cctacea often frequent the neighbourhood of the island
at this time, droves of dolphins and porpoises swimming
about with great activity ; and occasionally an immense
rorqual may be seen, raising his enormous back at in-
tervals from the water, and is to be observed coursing
round and round the island."

On one of his visits to the Isle of May, he observed
that at a considerable distance from the land, the sea had
assumed a slightly red colour, and that this became
deeper and deeper, the nearer he approached the island.
The water too, he noticed, presented a very curious ap-
pearance on the surface, as if a quantity of fine sand were
constantly falling upon it. At first he thought this
might proceed from light rain, but, upon more attentive
examination, he found both the red hue of the water and
the motion on its surface proceeded from an immense
number of small Entomostraca. Some of these he col-
lected, and found them to be a species of the genus
Cetochilus.

1. CETOCHILUS SEPTENTRIONALIS. Tab. XXIX, fig. 1 a-y.

Goodsir, Edin. New Phil. Jouru., xxxv, 339, t. 6, f. 1-11.
Baird, Trans. Berw. Nat. Club, ii, 156.

animal is about one and a half, or
two lines long, of a bright red colour, and slightly trans-
lucent. The thoracic and abdominal portions of the body
are distinct, each portion being divided into six segments.

:W i ; urn MI KNTO.MOSTKAI \.

The cephalo-thoracic segment is furnished with two sty-
liform appendages (t. XXIX, f. 1 a), instead of having
the moveable beak of Anomalocera ; these very much re-
semble antennae in appearance, and are described as such
by Goodsir.*

The antennae are very long and slender, being longer
than the body of the animal, and composed of twenty-four
articulations, the twenty-second and twenty-third are
each provided with a long seta, pointed downwards and
inwards.

The antennules (f. 1 c] consist of two branches, arising
from a common footstalk, and are of nearly equal
length. The one is divided into two articulations, the
first of which is the longest, and is furnished with a long-
seta at its extremity, the second having its extremity
armed with a number of very long seta'; the other consists
of two articulations also, the first, of which is considerably
bent, flattened, and armed with eight long spines on its
inner edge ; the second much shorter, and having two
long setae on its inner edge, and three from the extremity.
The eyes are two in number, but are exceedingly small.

The mandibles (f. 1 b] consist, as in Anomalocera,
of a strong plate, having a good many teeth on its inner
extremity, the most external one being strong, and
slightly curved ; and a palpiforin branch arising from its
upper surface, which is composed of two brandies, rising
from a common footstalk, one branch being divided into
two articulations, and the other having only one.

The first pair of foot-jaws (f. 1 d) resembles much
the same organs in Anomalocera, consisting of a basilar
joint, not so heart-shaped, with t\\o other articulations,
the last being very deeply notched, or lunate, instead
of being cleft to the base, but all armed witli long
seta-. The second (f. 1 c) is composed of two articu-
lations, each of which is knobbed on its inner edge,
and armed with twelve long, finely-plumose seta1, those

I HC Clt.

NOTODELPHYS. 237

of lower joint arising in pairs. The third pair of foot-
jaws (f. I/) is composed of seven articulations, the
basal being the largest, the others diminishing in size as
they succeed, and all armed with a number of long seta?
on the inner edge.

The legs are five pairs, all formed alike. They con-
sist (f. 1 ff) of a common footstalk, of two joints, and
two branches, each of which is divided into three articu-
lations. The external branch is much the larger of the
two, and has the last articulation the longest, and armed
with several rather long setae. The internal branch is
about as long as the first two segments of the external
portion, and the articulations are short and setiferous.
The fifth pair is formed like the others.

The abdominal portion of the body is small and slender,
the animal generally carrying it curved upwards. The
last segment is bilobed, and each lobe gives off five
tolerably strong setae or spines. The alimentary canal
consists of a simple straight tube.

Hob. — Frith of Forth, H.Goodsir, W. Thompson, Esqrs.

••.

Genus — NOTODELPHYS.*

The genus Notodelphys of Allman must form the type
of a new family. Till we are better acquainted with it, we
must place it here provisionally, as it has many things in
common with both the Cyclopidse and Cetouhilidse, though
it differs materially from both.

Character. — One eye. Head and first ring of thorax
consolidated together. Thoracic portion of body consists
of four, and abdominal also of four segments. Superior
antennas many-jointed; inferior prehensile. Foot-jaws,
four pairs. Ovary consists of a large sac, placed behind the
last thoracic ring, and within the parietes of the body.

* From j'wrof. tcrfmm, back ; and diXtivt;. matrix or womb.

23s

ISIIITISII i;vro.MosTii.\< A.

Only one species has as yet been observed, which Mr.
Allman has described at length in the ' Annals and Maga-
/.ine of Natural History' for July 1847. It is found
swimming fively in the branchial sac of the Axcnlia rom-
munis, and has been collected in various parts of Ireland.
It was first publicly noticed by Mr. Paterson of Belfast,
who briefly mentioned it at the meeting of the British
Association in 1843. The species has been named by
Allman —

1. NOTODELPHTS ASCIDICOLA. Tab. XXX, figs. 7, 8.
Allman, Ann. Mag. Nat. Hist., xx, 1-9, t. 1, 2, f. 1-22.

The cephalo-thoracic segment is prolonged anteriorly
into a kind of beak, which is not moveable. Attached to
this segment we find the eye, two pairs of antenna?, the
organs of the mouth, and one pair of natatory feet.

The eye is situated, as in the Cyclopidae, in the centre
of the superior and anterior portion of this segment. It
is tolerably large, and is single.

The superior antennae consist of about twelve short
articulations, each provided with one or more setae. The
inferior antennae (f. 7 a] are not branched, and arc formed
of four joints, the last of which is in shape of a curved
prehensile claw.

The labrum is well developed, and the mandibles (f. 7 b)
are strong organs, furnished with several stout teeth on
their cutting edge.

The first pair of foot-jaws (f.7c) consists each of a flattened
peduncle and two brandies; one having six, the other
three articulations, and bearing se\eral long, stout, and
finely plumose scta\ The second pair of foot-jaws (f. Id) is
very similar to the first, but their two branches have fewer
joints; one having three, and the other only one, but both
terminated by plumose sel;e. The third pair (f. 7 f) is
composed oi'ti\e articulations, the basal being UTV large,
and the succeeding small, and furnished with stiff, not
plumose seta'. The fourth pair (f. If) is smaller, formed

NOTODELPHYS. 239

of three joints, and having the seta? which spring from
them partially plumose.

The feet are four pairs in number, and are all alike (f. 1 y}.
They consist, each of two branches, springing from a basal
lamina of two joints, and each branch composed of three
articulations, copiously furnished on their inner edge with
plumose seta3. Each of these feet is attached to a cor-
responding segment of the thorax.

The abdomen is somewhat cylindrical, and terminates
in two caudal appendages, each carrying at the extremity
four short, plumose setas. The fourth segment of the body
is of a peculiar formation, having in its dorsal portion a
large hollow receptacle for receiving and containing the
ova. In the angle between this sac and the upper surface
of the ring, of which it forms a part, there is an opening
by which the eggs escape when they have arrived at
maturity. At first emerging from the ovum the young
animal is very like in form to the young of the Cyclops ;
but its changes have not been traced from this larva state
to its full growth.

Halt. — Belfast Bay ; Strangford Lough, county Down ;
W. Thompson and G. C. Hyndman, Esqrs. Killery
Bay, county Galway ; R. Ball and W. Thompson, Esqrs.
Bangor, county Down ; R. Paterson, Esq. Glandore
Harbour, county Cork, Dublin Bay, and Southampton
Water; George J. Allnian, Esq. In the branchial sac of
the Ascidia communis.

~1<) BRITISH KNTO.MOSTUAf'A.

LEGION III— P/ECILOPOD A.

I'ITILOPODA. I., i faille, Cuv. Regne An., iv.
— Desmarcst, Cons. gen. Crust.

Z«w//, Diet. Sc. Nat., \i\. .rJI.

ROH.I-. Crust, dc la Mcditerr.

Buif<l, Trims. Berw. Nat. Club, ii.
TIIKCATA, Lnf,riltr, Hist. Nat. Crust., iv; Gen. Crust, et Insect., ii.

— Leach, Edin. Encyclop., art. Crustaceology.
BHANCHIOPODES PARASITES, Lamafck, An. s. Vert., edit. 2d, v. 200.
CRUSTACKS SUCEURS (_/*//-.v i, I/. 1'jlicanh, Hist. Nat. Crust., iii.
PAKASITA, iV/,w/.v/V/-, licit, zur Naturg. der Raukenfusscn, p. 54.
CoBMOSTOMATAj />/',.»>, Proc. Am. Acud. Arts and Sc., IS ID, p. 53.

. — Mouth not possessed of organs fitted for
mastication, having instead an apparatus adapted for
sucking. I'Vt't, parti}' formed for walking or prehension,
and part branchiferous, and fitted for swimming. Body,
in the greater number, inclosed almost totally within a
buckler, consisting generally of one piece, occasionally of
two. Parasitical upon fishes, &c.

ORDER SIPHONOSTOMA.f

SIPIIONOSTOMA, ].<ili-«'illi', Cm. Hogne Aniin., iv.

M. Edicni-tk, 1 1 ist . Nat. Crust., iii.

l\<ni.r, Crust, dc la ^1 edit err.

/!</>',•</, Trans. Benv. Nat. Chili, ii.
PKKCMOM I;A, latreilie, Ilisi. Xat. Crust., iv; Gen. Crust. et Ins., ii.

Lear//, Kdin. Kneu-ln])., art. Crustaceolog v .
CALIGACEA, /),/,/>/, Proc. Am. Acad. Arts and Sc., 1M'.), p. 53.

Character. — Moiilli furnished with a siphon, which
possesses stylifonn m;mdil»les. Thorax composed of
sc\iTiil distinct rings, and having three or four pairs of
feet. Knot-jaws Avrll developed.

M. Edwards divides the order Siphonostoma into two
families, the I'dtdci-pliiilcs, and the Pachyvjiluilcs.

The Peltocephalea are distinguished by their having

I'Vdin -IIIKI\OC, varion.s; ami trove, Foot.

' I rODl TI,;,,.,,.. a lulio: and aro/m, a inmitll.

PELTOCEPHALA. 241

their head, in the form of a buckler, furnished anteriorly
with frontal plates and short antennae consisting of two
flattened joints. In the Pachycephales, on the contrary,
the head is not shield-shaped ; there are no frontal plates,
and the antennae are of considerable length, composed of
five or six articulations.

TRIBE 1—PELTOCEPHAL4* M. Edwards.

In all the genera belonging to this section we distin-
guish a head, a thorax, and an abdomen.

The head is generally larger than both thorax and
abdomen together, is of a rounded form, somewhat trun-
cated posteriorly, and having in the front part two small
plates stretching across transversely.

The thorax varies in the different families, sometimes
consisting of only two articulations, at others of three ;
and, in some instances, even of four. In some it is com-
posed of articulations, which present nothing remarkable
in their structure, whilst in others these are covered with
plates, or broad flat scales, which resemble very much
the parts of some insects called the Elytra.

The abdomen is always very small, and is terminated
either by two small ciliated plates, or by a body consisting
of three leaflets.

The antennae are small, and are only one pair, com-
posed of two or three short, simple articulations.

The mouth-apparatus consists of a large well-developed
sucking-tube and appendages, adapted for puncturing
the skin of the animals upon which they live as parasites,
and for sucking the juices of their bodies ; and three pairs
of foot-jaws, constructed for enabling them to fix them-
selves upon their prey.f

Their feet are four pairs, the greater number in general
being adapted for swimming.

* From Trt\Tr), a short shield ; and /c^aXov, head.

f Vide the more full description of these parts in Caligida.

16

242 BRITISH ENTOMOSTRACA.

Thov arc all parasitic upon fishes and other aquatic
animals; and, when young, undergo a series of meta-
morphoses like what takes place in the Cyclopidse.

Family— ARGULIDJ3.

ARGULIENS, M. Edwards, Hist. Nat. Crust., iii.
AKGTJLID^:, Leach, Diet. Sc. Nat., xiv.

Desmarest, Cons. gen. sur les Crust., 329.

Baird, Trans. Berw. Nat. Club, ii, 157.
ARGVLINA, Kroycr, Tidsskrift, i, 202.

Burmeister, Beit, zur Naturg. der Raukeufuss.

Character. — Head in form of a large circular-shaped
shield. Antennae short, thick, two-jointed ; second pair
of foot-jaws absent, being replaced by a pair of large
suckers.

Genus — ARGULUS .

ARGULUS, MiUler, Entomostraca.

,1i' fine Jils, Laninrrk, Latreill?, Cuv. Regne Anim., iv.

Leach, Desmarest, Burmeister, Ilerrick and Dana, M. Edwards, fyc.
MONOCULUS, Linnaim, Fnlif'x-it'x, Ouvier, Manuel, fyc.
OZOLUS, iMtreille, Hist. Nat. Crust., &c.
BINOCULUS, Geoffrey, Latrcille, Genera.

Character. — As there is only one genus yet known, the
characters given to the family will suffice also for the
genus.

Bibliographical History. — Baker is the first author in
this country who seems to have taken notice of the
Argulus. In his ' Employment for the Microscope,' 1753,
he gives a figure of one which he tells us " was found
sticking to a large carp just taken out of the canal in
Saint James's Park." In size it was about .'.tliof an inch
long, and nearly as broad. I le figmes another, consi-
derably smaller, taken from the banstickle or prickleback ;
and as it differed from the former slightly in shape as

ARGULUS. 243

well as size, he concludes that they were distinct species.
The one he calls the " Louse of the Carp," the other, the
"Louse of the Banstickle or Prickleback." Long previous
to this, however, Leonard Baldner, an intelligent fisher-
man belonging to Strasbourg, had noticed a species of
Argulus infesting the fishes in the neighbourhood of that
town.

In a manuscript, which bears the date of 1666, entitled
" a description of the birds, fishes, and insects, found in
the neighbourhood of Strasbourg," written in German, a
copy of which is now in the Library of the University
there, he speaks of this little creature under the name of
" Pou de poissons." Hermann informs us that his father
had consulted the original manuscript written by Baldner
himself ; and which appears, from the account given of it
by Herissant, in the ' Bibliotheque physique de la France,'
No. 1180, to have been presented to M. Spielmann, Pro-
fessor of Medicine in Strasbourg, by the relatives of Baldner,
citizens of that town. It was very difficult to be read,
but it contained many excellent observations. Several
copies, written by different and more legible hands, seem
to have existed, for Mr. Willughby must have had one,
as he quotes from it repeatedly in his works on Birds and
Fishes ; and another copy exists at Mayence. M. Her-
mann thought so highly of it, that it was at one time his
intention to have published it, but his death prevented
this design being carried into execution. Frisch, in his
'Insecten in Deutschland,' torn, vi, published in 1740,
gives a very imperfect figure of an Argulus, and describes
it shortly under the name of " Fisch-laus." Loefling, in
the 'Act. Soc. reg. Scient. Upsal,' 1751, describes the
same animal at greater length, under the name of " Mo-
noculus cauda foliacea plana;" but though he has entered
more minutely into the details of its organization than his
predecessors, his accompanying figures are very indif-
ferent. "It is found," he says, "upon the Pike and
Perch, and is called by the natives of Sweden, where his
specimens were taken, the Abbor-lus and Gadd-lus."

0 I I BRITISH ENTOMOSTRACA.

Linna-us, in the tenth edition of his ' Systema Naturae,'
1758, and again in his 'Fauna Suecica,' 2d edit. 1761.
notices the Argulus under the name of J\Io)iocult(sfo/i<ic<>//x,
In the 12th edition of the 'Systema/ 1707, he unfor-
tunately, however, confounds it with the Caligus, under the
name of Monocuhis piscinus. Under this name he refers
to the Argulus, as described by himself, in his two last-
mentioned works, and by Loefling ; to the Caligus, as
described by Master, in his ' Opuscula Subseciva / and to
the Prosopistoma, figured by Geoffrey, in his ' Insectes de
Paris.' Fabricius, in his ' Systema Entomologist/ 1775,
and Gmelin, in the 13th edition of the ' Systema Natune.'
repeat this error, giving the species ~M<>,i<><-tilitx /y/.vr/'/^/.v,
with all the faulty svnonvma. Geoffrov, in his ' Insectes

»/•'*/ */ '

de Paris/ 1702, observing that this, and some other
species of Entomostraca, had two eyes, formed the genus
Binoculus to receive them. This little parasite he had
once found upon the stickleback ; but not having time to
examine it attentively, he has given no lengthened de-
scription, merely noticing it under the name of Binocnln*
yastcrostei."*

Ledermiiller, in his 'Amusements microscopiques/
])art i, 1764, has given a figure of the Argulus, and de-
scribes it as "a small aquatic insect," which he thought
worthy of attentive consideration. His figure is enor-
mously magnified, and very indifferent. Midler is the
first author who has given it the name of Argulus. In
his ' Entomostraca/ 1785, he established the genus
Argulus, and described two species, indicating, besides, a
third. The last is a very doubtful species, while the two
first are the same, the only diflerencc being in age,
Miiller erroneously considering the young animal as dis-
tinct from the adult.

' The second species of his genus jlinor-iilus lie calls 7>Y//wW//.v 1m mi-
K)ilii/-i-i<-tts, .-mil i.'-ixo ;ts Mmnmns (lie rd'crciiccs of Frisoh, Loefling, and
LiniKms i loth edit.), to the ijriiiis Arjrulus. Aii examination <>f the liirmv

arromjiain MILT Ilir description distinctly shou-.. lin\\c\cr, that this i., a totally

different animal, lu-injj the1 Prosopistoma of Lai rrille.

ARGULUS. 245

Fabricius, in his ' Entomologia Systematical 1793, in-
troduces a species amongst his Monoculi, under the name
of 3Iotioc. Argulus ; but though he quotes the Argulus
delj)hini of Milller as being the animal he alludes to, his
description of the species, which he gives at considerable
length, is totally different from that of Miiller, or any
other author.

Cuvier, in his ' Tableau element. del'Hist. Nat./ 1798,
mentions the Argnlus under the name of Monoculus
gi/rini, or " Pou de tetard," having found it upon the tad-
pole of the common frog. The same celebrated author
read, at one of the early meetings of the Philomathic
Society, a paper containing a number of excellent observa-
tions upon the anatomy and physiology of the same
creature, under Geoffrey's name of " le binocle de gaste-
roste." For the contents of this paper we are indebted
to M. Latreille, who, in his ' Hist, Nat. Crust.,' 1802,
describes the species of insect mentioned by Cuvier under
the name of Ozolus gasterostei, retaining the generic name
of Argulus for the species erroneously described by Miiller
from the young individual. In his later publications, how-
ever, he cancels the genus ; in the ' Genera Crust, et Ins.,'
1806, referring it to the genus Binoculus of Geoffrey, and
in the ' Regne Animal,' 1829, adopting Miiller's name of
Argulus.

Hermann fils, in his 'Memoire apterologique,' 1804,
has made a good many observations upon this little
creature, and given two tolerably good figures of it. The
most elaborate description, however, that has been given
is by Jurine fils, in the ' Ann. Mus. d'Hist. Nat.' 1806.
In a very lengthened memoir he has given a complete
history of what had been known previous to his time, and
followed that up by most careful dissections and patient
observations as to its habits and nature. The memoir is
accompanied with excellent figures, and indeed leaves
little to be done by future labourers in the field but to
corroborate his statements. Hitherto all the descriptions
of and observations made by different naturalists upon

246 BRITISH ENTOMOSTRACA.

the Argulus referred to one species, which seems pretty
generally diffused over Europe.

In 1837 [Messrs. Herrick and Dana described another
species in the ' American -Journal of Science and Arts' for
that year. It was found in Mill River, AVhitneyville, prey-
ing upon the fish called the Sucker, a species of Cato-
st 01 n us. The description of this species was accompanied
with most elaborate anatomical details, and illustrated
with numerous good figures. They gave a very accurate
description also of the young or imperfect animal. Various
other notices of the Argulus have been published since
that. A short account of the common species was inserted
by Mr. Thompson, of Belfast, in the ' Annals and Maga-
zine of Natural History' for 1839, vol. v, with a very in-
teresting account of the habits of the little creature, as

observed by himself in an individual taken alive at Belfast.

"
and kept by him for some time ; and in the ' Memoirs of

the Helvetic Society' for 1845, M. Vogt has given some
very interesting details of the same species, with good
figures, illustrative of some parts of its anatomy. A third
species has been described by Mr. Gould, in his ' Inverte-
brataof New York,' under the name ol\ //Y//////.V <7/Wr, and
more recently, a fourth species has been added to the list
by M. Lucas. It was found by him in Algeria, and is
figured in the recent 'Exploration scientiiiqiie del'Algerie/

Anatomy and Physiology, $'c. — The body of the Argulus
is covered by a carapace of a greenish hue, and nearly
transparent. It is slightly convex, obtusely rounded in
front, and deeply notched behind. This deep notch is
occupied by the thorax, which at first sigh I almost escapes
observation, the animal apparently having the cephalo-
thoracic portion of the body covered altogether by the
broad carapace. This may be divided into three parts. The
lir-t. or anterior, is rounded in front, and prolonged behind,
terminating in a blunt point. The other two, the posterior
portions, ;irc of mi oval form, and cover the lateral parts
of the animal. They arise towards the middle of tin

ARGULUS. 247

body, and extend downwards, covering a portion of the
thorax. The line of separation between these lateral
lobes and the anterior division is very distinctly to be
seen, forming a mark like the letter V. In the anterior
portion we see the eyes and the brain shining distinctly
through the shell, and in the latero-posterior portions we
trace a highly-coloured series of ramifications, springing
from a trunk which conies direct from the stomach.

The eyes are lodged in the thickness of the shell, and
appear as two dark spots placed at a little distance from
each other. They are situated on the upper part of the
anterior portion of the carapace, are immoveable, of a
spherical form, and of a very deep violet colour. Each
eye is inclosed in a membranous sac, and, like the eyes of
the Branchiopodse, are areolar.

The brain appears in form of a small black point, situate
behind the eyes, and consists of three lobes, of about equal
size. Nerves are given off from this mass, which may be
seen running clown, to supply the abdomen and natatory
legs.

The antennae (t. XXXI, f. ci) are situated in front of
the eyes, and are completely concealed under the anterior
edge of the carapace. They are short and stout, consist-
ing of two joints. The basilar joint is broad ; the terminal
equally broad at the base, gradually tapers to a point,
and terminates in a curved horn-like point. This joint
has, on its external edge, a slender appendage, three-
jointed, directed outwards, and extending beyond the
branch from which it springs. Arising close to the base
of these antennae we find a pair of organs (t. XXXI, f. b),
which have been described by Jurine, and Dana and
Herrick, as a second pair of antennae. They are smaller
than the antennae, and consist of four articulations. The
basilar joint is large, and the other three gradually become
smaller and smaller, the apical one terminating in three
or four very small spines. The anterior pair of these
organs is described by Cuvier as the mandibles. Jurine
considers them as organs by means of which they assist

248 BRITISH ENTOMOSTRACA.

the animal to fix itself to its prey. Ledermiillcr describes
them as antennae, and since his time, Dana and Herrick,
and M. Kdwards, have shown them to be the true antennae
of the animal ; while, according to the latter author, the
posterior pair of organs are the first pair of foot-jaws.

The organs of the month are of a complex nature. The
most prominent part is a long, sharp-pointed siphonal
tube (t. XXXI, f. d, c). It arises at a considerable distance
behind the antenna*, and is formed of a very fine tube, in-
closed in a flexible sheath. The extremity terminates in
a very sharp point, at the top of which we see the orifice
of a canal, hollowed out of the interior, which is prolonged
to the commencement of the oesophagus. It is moveable,
the animal being able to thrust it out rapidly from its
sheath, carry it right or left, and project it far enough to
reach the anterior edge of its shell. It can also cause it
to enter into its sheath with the same rapidity by means
of a slender muscle, which at one part is attached to the
base of the sheath, and at the other to the middle of the
trunk. The sheath is nothing but a prolongation of the lip,
while the sharp-pointed portion constitutes the analogue
of the mandible. Below the insertion of this siphon we
see a convex, oval mass (f. d], containing the rest of the
apparatus of the mouth. According to Dana and Herrick,
who have described this part with great care, these con-
sist of what is perhaps the inferior lip, and t\vo pairs of
maxilla; in a rudimentary state. These authors consider
that J urine, who describes the convex, oval mass men-
tioned above as the heart, is quite mistaken; and that the
motion which he considered the palpitation of the heart,
is nothing but the rapid motion of the maxilla:.

The feet of the Argulus are generally described as of two
dillercnt kinds : one used either for walking with or
fixing itself upon its prey ; the other adapted for swimming
when the animal is at large. What have been called the
ambulatory legs are two pairs in number. They are the
M-cond and third pairs of foot-jaws. The anterior pair, or
second pair of foot-jaws, (t. XXXI, f. c,/) is of a very

ARGULUS. 249

peculiar construction. They are in the form of short,
hollow, flexible cylinders ; the pedicle by which they are
attached to the animal being thick and muscular, and the
extremity terminating in a broad, circular, horizontal rim,
almost cartilaginous, having a membranous margin, fringed
all round with numerous rays, which, according to Dana
and Herrick, are many-jointed. Four muscles are attached
to the base of each of these organs, and extend up the
sides. By this organization the animal can make use of
them as real suckers, or cupping-glasses, to fasten itself
to the fish upon which it lives, and also to walk with,
when it wishes to change its position. By contracting
these muscles, it can exhaust the cavity of the sucking-
disc, producing a vacuum, and thus enabling it to adhere
firmly to the surface upon which it is placed. When it
wishes to change its place, it relaxes the muscles first of
one sucker, carrying it forwards, and then the other, alter-
nately, as was long ago observed by Loefling. The second
pair of ambulatory legs, or third pair of foot-jaws (t. XXXI,
f. </), arises immediately below these suckers, and is very
different in conformation. They are somewhat cylin-
drical, and are composed of five articulations. The first
two are much larger than the others, have their surface
roughened with small spines ; and at the base of the first
joint, we see three strong teeth. The last joint gives off
at its extremity two small hooks. These organs are called
the prehensile feet by Dana and Herrick, and no doubt
they do assist the animal to secure itself more firmly in
its position. The natatory feet are four pairs, arising in
a series on each side of the thorax, and partly covered by
the lateral portions of the carapace. The first three pairs
(t. XXXI, f. h, i,} consist each of a large fleshy peduncle, or
basilar portion, which is obscurely divided into two joints,
and gives off at its extremity two long branches, beauti-
fully fringed, with transparent and delicately plumose
cilia ; while a third shorter branch, equally plumose,
arises from the base of the two preceding, and is curved
backwards and inwards. The fourth pair (t. XXXI, f. £,/)

250 BRITISH ENTOMOSTRACA.

is destitute of this recurved branch ; but it is otherwise
formed like the three preceding.

The thorax has been described above as occupying the
deep notch observable in the carapace. Immediately
behind the suckers it becomes distinct from the head. It
consists of four separate joints, from each of which arises
a pair of the feet just described, and traces of a fifth are
indistinctly visible.

The abdomen, as in all the Siphonostoma, is very small.
Most authors have described it under the name of tail,
considering the thorax to be the abdomen. It consists of
a broad plate, which at the base is bilobed, and carries,
close to where the separation commences, a pair of rudi-
mentary organs of an oval form, and ciliated on the mar-
gins.

In the female we see, at the base of each of these lobes,
a small black, spherical body, which does not occur in the
male.

The intestinal canal commences at the base of the si-
phonal tube, and extends to the bifurcation of the ab-
domen, where it terminates by the anus.

Upon viewing the little animal from above, we observe
very distinctly, as has been already mentioned, a ramifica-
tion of opaque tubes running through the lateral portions
of the carapace (t. XXXI, f. 2). They arise from a single
branch which springs from the stomach, and extends on
each side to near the edge of the shell.

The stomach, or commencement of the alimentary canal,
is of considerable size, and of an oval form ; and these
ramifications are considered by Jurine as the intestines.
Inferiorly the stomach narrows into a pyloric termination,
which opens into a kind of crccum, having two appendages
springing from its anterior part. This again contracts
into the rectum, which descends to the bifurcation of the
abdomen, and there opens by an oval orifice situated in
the centre of the bifurcation.

The female Argulus differs from all the other Siphono-
stoina in not having like them external ovifcrous sacs. The

ARGULUS. 251

matrix is contained in the thoracic portion of the body,
and in a gravid female the whole cavity of the thorax is
occupied with the eggs. These escape by a very short
oviduct, whose orifice is placed between the two natatory
feet.

The male organs have been described by Jurine, and
he appears to have been the first to detect them ; indeed
they have not been described by any other individual.
According to this author, they are situate on the last two
pairs of feet. On the anterior edge of the first joint of the
fourth pair, and close to its extremity, there is a brown
conical tubercle of a horny nature, the base of which is
armed with a small hook directed backwards. Corre-
sponding to this, we find on the posterior edge of the first
ring of the preceding, or third pair of feet, a vesicle filled
with transparent liquid ; apparently, says Jurine, destined
for fecundation. The male organs are thus double. The
circulation of the blood can be distinctly seen in several
parts of the body. The blood is a transparent fluid, com-
posed of small, round, diaphanous globules, and is pro-
pelled to the different parts of the body by distinct pulsa-
tions, which occur about once every second.

The Argulus in this country is found upon various fresh-
water fishes. In the neighbourhood of London it is most
commonly to be met with upon the stickleback ; but it has
been taken also upon the carp and the roach ; and in other
places it has been found upon the trout, the pike, the
perch, and even upon the tadpole of the common frog.

An individual taken from the salmon trout at Belfast,
by Mr. W. Thompson, was placed by him in water in
which salt was dissolved, till it became to the taste like
sea- water, and it remained for four or five hours active and
lively.

The species which has been described by Dana and
Herrick, in North America, was taken from the fish
called the Sucker, in the water of Mill River, near Whit-
neyville, into which the tide from Newhaven Harbour

252 BRITISH ENTOMOSTRACA.

enters, and renders, consequently, brackish, so that it
would appear this little animal, though in reality a fresh-
water species, is not injured by an admixture of salt.

The Aryulm foliaceiis is an exceedingly pretty and
graceful little animal ; and as it can leave the fish upon
which it feeds, and swim freely in the water, there are
many opportunities for watching its gambols through its
native element. It generally swims in a straight line, but
it frequently suddenly changes its direction, and often
turns over and over several times in succession.

Lederm idler says he has seen an individual turn over
thus a hundred times in a minute, and that it swam after-
wards with such velocity, sometimes skimming the sur-
face, at others plunging deeper in the water, that he could
scarce follow its motions with his eye. Sometimes it will
attach itself to the side of the vessel in which it is kept;
and we may then observe that though, as far as progres-
sive motion is concerned, the little creature is at rest, the
natatory feet are in constant motion. Like those of the
Branchiopoda, they serve the animal not only for swimming
with, but also for respiration. Their structure is pre-
cisely similar, and their use the same. \Vhcn swimming
free in the water, and wishing again to fasten itself to its
prey, the little animal approaches a fish, quietly allows
itself to be hurried along in the current caused by its
motion through the water, till it touches it, when it im-
mediately fastens itself to it, choosing, according to
Jurine, as its place of residence the under part of the pec-
toral fins.

Loefling states that the part where the Aryulus foliacens
is chiefly found is within the gills, or immediately out-
side ; and Dana and llerrick inform us that their An/aliix
('(iluN/niiii was always found within the branchial cavities;
but when the fish itself was immersed in fresh water the
parasite forsook the gills, and, after swimming about for
some time, would often attach itself to the anterior part
of the body.

.) urine observed that the fishes seemed to be afraid of

ARGULUS. 253

the little intruder, and that however eager after food they
might be, they would never willingly touch an Argulus ;
and that if by chance a fish should swallow one, it would
nlmost immediately afterwards be rejected.

The males are always considerably smaller than the
females ; and appear, especially in summer, very ardent in
pursuit of them. They course up and down over the whole
surface of the fish in search of a mate, and should they
not succeed in meeting any, they leave their habitation,
and go elsewhere seeking for one. When they succeed,
the male mounts upon the female's back, and carrying his
body laterally he crosses that of the female, embracing her
at the same time with his natatory feet. This copulation
frequently endures for several hours, and during that
time they adhere so closely, that they cannot be separated
without considerable difficulty. In the unimpregnated
female the matrix is very small ; but soon after fecunda-
tion it begins to increase in size, and in a short time it
occupies almost the whole cavity of the thorax. The
number of eggs is very considerable, in the Argulus folia-
ecus amounting sometimes to 400 ; in the Argulus Cato-
stomi upwards of 1500 have been seen deposited by one
female. They carry their eggs for a period between thir-
teen and nineteen days ; and then, when the female is
ready to spawn, she detaches herself from the fish, upon
which she has been living, and seeks a suitable place to
deposit them. This is either upon a stone or some solid
body, and as she lays them, she glues them together, so
that they might be all taken up in a mass. They are laid
side by side in rows, and are at first of an oval form and
of a white colour. They soon after become of a dirty
yellow, and thirty-five days after being laid, the young are
hatched. In form they resemble a good deal the adult,
but differ considerably in construction and development
of their organs. Deceived by this, Miiller forms of the
imperfect young a distinct species, — an error which Jurine
has pointed out. The shape is oval, or somewhat
form, and the eyes and siphon are perfectly formed.

254 BRITISH ENTOMOSTRACA.

The natatory feet are very imperfectly developed ; their
function being supplied by two pairs of organs in form of
mini, placed on the anterior part of the body. The first pair
corresponds with the antenna in the perfect animal ; the
antenna itself being well developed, and the appendage
which projects from its posterior edge being enlarged into
this long ramns, constituting the chief part of the organ.
The second pair corresponds with the first pair of foot-jaws
in the adult. These organs are large, consisting of several
articulations, the terminal one of which gives off several
long setae. By means of these rarni the little creature
moves with ease by bounds, like the Daphnia. The
sucking-discs are not yet formed, their place being sup-
plied by a pair of large feet, broad at then- base, and ter-
minating in a prehensile hook, by means of which the
animal can fix itself upon its prey. The organs imme-
diately following these are only slightly developed, and
correspond with the third pair of foot-jaws, and the nata-
tory feet are little more than rudimentary. In this state
the young animal continues for about six days, when it
casts its shell. Three days after the first moult, it changes
its shell again ; and two days after that a third moult
takes place. By this time we find the rami have dis-
appeared, the natatory legs have become developed, and
the sucking-discs have assumed somewhat of their shape
and appearance.

Two days after this the fourth change of shell takes
place, when the sucking-disc has become perfect. Six
days later, the fifth moult occurs, when the sexual organs
make their appearance ; and after the sixth change, which
takes place six days subsequently, or twenty-five days
from their being hatched, the animals commence to breed.
They have now, however, only attained half their full
gnmth, but gradually augment in size after successive
moults, which take place every six or seven days.

An experiment conducted by Jurine, and fully detailed
by him, tends to prove that the Arguli do not, like some
of the Branchiopoda, become pregnant without the inter-

ARGULUS. 255

vention of males. He isolated six young females imme-
diately after birth. They underwent their usual changes
of shell, till the time when the sexual organs became fully
developed ; but though kept for some time, no appearance
of impregnation took place. To one of these he gave a
male ; copulation took place, and the animal became preg-
nant. The other five remained unimpregnated, and all
died of a peculiar disease, without having shown even the
slightest appearance of ova.

1. ARGULUS FOLTACEUS. Tab. XXXI, figs. 1, 2.

MONOCULUS FOLIACEUS, Lmtueus, Syst. Nat., edit. lOtb, i, 634, No. 2,

175 8; Faun. Suec., edit. 2d.
ARGULUS FOLIACEUS, Jurine fils, Ann. Mus. d'Hist. Nat., vii, 431,

t. 26, 1806.

Leach, Diet, des Sc. Nat., xiv, 529.
Lamarck, Hist. Aiiim. s. Vert., v, 207-
Latreille, Regne Animal, iv, 195.
Desmarest, Consid. gen. sur les Crust., 331,

t. 50, f. 1.

Guerin, Iconog. Regne Anim. Crust., t. 35, f. 1.
Burmeister, Nov. Act., xvii, 332.
M. Edwards, Hist. Nat. Crust., iii, 444 ; Regne

Auim., edit. Crochart, t. 78, f. 1.
Thompson, Ann. Nat. Hist., v, 221.
Garner, Nat. Hist, of Staffordshire.
Bosc, Man. d'Hist. Nat. Crust., ii, 220.
— Kroyer, Tidsskrift, vol. i, pp. 190-203.

Vogt, Nouv. Mem. Soc. Helvet., vii, t. 1, f. 2.
ARGULUS DELPHINUS, Midler, Entomost., 123, 1785.

Hermann,M.em. Apterol., t. 5, f. 3, and t. 6, f.ll.
Latreille, Enc. meth., t. 334, f. 1-22, art. Ar-

gulus, p. 100.
ARGULUS CHARON, Mutter, Entomost., t, 20, f. 1, 2.

Latreille, Eiicycl. method , 1. c.
ARGULUS ARGULUS, Leach, Edin. Eucyclop., 1814, vii, p. 388, art.

Crustaceology.
MONOCULUS DELPHINUS, Gmelin, Syst. Nat., edit. 13th, 1788.

Manuel, Encyc. meth., vii, 730.

MONOCULUS ARGULUS, Fabricius, Ent. Syst., ii, 489, 1793.
MONOCULUS GYRINI, Cuvier, Tab. element., 454, 1798.

256 BRITISH ENTOMOSTRACA.

BINOCULUS GASTEKOSTEI, Geoffroy, Ins. de Paris, ii, 661, 1762.

l.<it,-i-iU?, Gen. Crustac. ct lus., i, 14.
OZOLUS GASTEEOSTEI, Lutfe'iH?, Hist. Nat. Crust, ct Ins., iv, 128,

t. 29, f. 4, 1802 ; Diet. d'Hist, Nat.

LOUSE OF THE CARP, Baker, Employm. for Microsc., 371, t. 11, f. 1 i.
LOUSE or TUE BAXSTICKLE, Baker, 1. c., 37f>, t. \\, f. 15.
PETIT INSECTS AQJJATIQ.UE, Ledcnm>llcr, Amus. Micros., part i, 76,

t. 37.

MONOCTJLUS CATJDA FOL1ACEA PIANA, Loefliliy, Act. SoC. Reg. Scicut.

Upsal, t. 2, f. A-D.

FISCIT-LAUS, Friscli, Insect, in Dcutsch., vi, t. 10, f. a.
MOXOCULUS CYPKINACEUS, Shaw, Naturalist's Miscellany, xviii, t.736.

Descrijtfidi). — The Argulus foliaceus is of a rounded,
oval shape, the front of the carapace notched on cither
side, and bluntly projecting in the centre. It is nearly
transparent, of a slightly greenish hue, and elegantly
marked on both sides by a series of ramifications of a
darker colour. The female is larger than the male, and
is distinguished, in addition to the ovaries, by a black
mark on each lobe of the abdomen. The last pair of feet
is not concealed by the carapace.

I fab. — On the carp and banstickle, St. James's Park,
Hnker. Trout (Salmo ffirio) and pike (J&o.r //"•///*),
W. Yarrell, Esq., J. Doubleday, Esq. Salmon-trout,
Belfast, AY. Thompson, Esq. Stickleback, llighgate Ponds,
Hammersmith, &c., W. 13.

Family— CALI6ID2B.
I.E, M. i:<l>>-, >>•</*, Hist. Nat. Crust., iii.
Baird, Trans. Berw. Nat. Club, ii.
(/////•/>•>, Isacli, Diet. tSc. Nat., \i\.
-, Ilisi. Nat. Eur. Merid., v, KH.

t, Cons. ^'11. Crust., o.'Jk
CALIGIX.V (/«//••••), A'/v/y/-, Tidsskrift, i, 200 (?).

— Bufu«'ixtt>ft Boitr. zur Naturg. dcr Kankcnfuss., p. 54, 55(?).
Dana, Proc. Amcr. Acad. Arts and Sc., IS 11), p. ."i I.

r. — Head in form of a large buckler, having
anteriorU large frontal plates. Four pairs of feet, \\hieh
are furnished \vith long j)lumose hairs. Antenna- small,

CALIGID7E. 257

flat, and two-jointed. Second pair of foot-jaws of two
articulations, and not in form of a sucking disc. Thoracic
segments uncovered.

Bibliographical His 1 'on/. — Linnaeus seems to be the
first author who takes notice of any animal belonging to
the genus Caligus. In his ' Fauna Suecica/ second edition,
1761, he shortly describes a species which lives upon the
salmon and haddock, inhabiting the Norwegian seas. He
designates it "Monoculuspiscinus," and quotes Martin as
his authority for the habitat. In the same work he de-
scribes a species of Pediculus, which is found upon the
salmon also, calling it the " Pediculus Farionis.'' From
the general description of this little creature, and more
especially from its possessing two long ovarian tubes, it is
evident that it is a species of Caligus, and from its being
found upon the same species of fish, it would appear to be
closely allied to the Monoculuspiscinus. In his ' Systema
Naturae/ 12th edition, 1767, he, indeed, distinctly affirms
this, and says it is " allied to the Monocidus piscinus from
its having two cylindrical bodies placed above the tail /'
and Gmelin, in his edition of 1788, under the species
" Pediculus Farionis," remarks, " that it scarcely belongs
to this genus." Strom, in his ' Physiske og Oeconomisk
Beskrivelse over Fogderiet Sondmor/ 1762, describes and
figures what may be two species of Caligus, but which are
perhaps only the male and female, under the name of
Fiske luus, or Pediculi marini; and Baster, in his
' Opuscnla Subseciva/ 1765, describes and figures also
two or three different species of this genus, accompanied
with considerable details. Both of these authors repre-
sent the animal with its head downwards, and considered
the two long ovarian tubes as antennae, mistaking the tail
for the head. These figures and descriptions appear to
have misled Linnaeus ; for, notwithstanding his having
already described the animal correctly in his ' Fauna
Suecica/ he subsequently, in the 12th edition of his
' Systema Naturae/ 1767, describes the Monoculuspiscinus

17

258 BRITISH ENTOMOSTRACA.

as consisting of two kinds, differing either in sex or
species, the one having two antennae longer than Hie body,
and the other having none. Strom again, in the ' Skrifter
Kiobenhavnske Selskab,' 1770, describes and figures an-
other species, and evidently a second time mistakes the
tail for the head.

In describing the Argulus, I have mentioned that
Linnaeus, in his twelfth edition of the ' Syst. Nat.,' con-
founded that animal with the Caligus. In the 'Fauna
Suecica' he described them as separate species ; but in
this latter work he not only quotes his own previous de-
scription of the Argulus as a synonym for the Caligus,
but he even refers to Loefling's figure of that animal as

O O

further evidence of their identity. This erroneous syno-
nymy is repeated by Fabricius, in his ' Sy sterna Entomo-
logiae,' 1775, and by Gmelin, in his edition of the ' Systema
Nature,' 1788. Slabber, however, previous to Gmelin's
edition, in his ' Naturkundige vciiustigingen,' 1778, had
given a figure, under the name of Oniscns lutosus, of a
species belonging to this family, and delineated the true
antenna? and some other parts very correctly.

0. Fabricius and Herbst seem also to have better
understood the anatomy of the animals belonging to this
group. The species which they have described, the former
in the ' Fauna Grcenlandica,' 1780, and the latter in the
'Berlin Gesellschaft Skrifter,' 1780 and 1782, are accom-
panied, especially the latter, with a number of details, and
arc pretty accurately described by both. Miiller, in his
' Prodrom. Zoologia? Danicre,' 1776, introduces the genus
under the name of " Binoculus," adopting that name
from Geoffrey ; but in his ' Entomostraca/ 1 785, he founds
the genus Caligus. Hitherto no zoologist had clearly
ascertained the situation of the eyes, and it was from this
apparent blindness that the generic name \\as suggested
to him. With regard to their exact situation, however
e\en lie Avas decei\ed, for though he really saw the true
eyes, he. yet did not consider them to be such, but
absolutely mistook a dill'erent. part altogether \ot\vith-

CALIGID.E. 259

standing this, his description of the genus and the two
species which he gives is better than any that had as yet
appeared.

Geoffroy described and figured, in his 'Insectes de Paris,'
1764, a small crustacean, under the name of Binoculus
hamisphaericus. It bears some resemblance to a Caligus,
and Linnaeus, in the 'Syst. Nat.,' twelfth edition, quotes
it as a synonym for his Monoc. piscinus. This is repeated
by Fabricius, in his work already quoted, ' Entomologia
Systematica,' 1793, and in the Supplement to the work,
1798. It is not, however, a Caligus, but a different
genus altogether, to which Latreille has given the name
of Prosopistoma. Manuel, in the ' Encyclopedic method.,'
1792, avoids this faulty reference, but falls into the error
of his predecessors with regard to the Argulus.

Cuvier mentions the Calygus in his ' Tableau ele-
mentaire,' 1798; and Latreille, in his 'Hist. Nat. Crust.
et Ins./ 18023 presents us with a lengthened account of
the genus, giving all the details made known to us pre-
viously by Muller and others. Risso, in his ' Hist. Nat.
des Crust, des Envir. de Nice,' 1816, and in his 'Hist.
Nat. de 1'Europe rnerid.,' 1826, mentions several species
belonging to the Caligidse ; Tilesius, in a paper in the
' Mem. de 1'Acad. Imp. des Scien. de St. Petersbourg,'
1815, details at some length Muller' s two species, and
adds some interesting notices of a number of creatures
allied to this family, as connected with the luminosity of
the sea ; and Lamarck, in the first edition of his ' Hist.
Nat. des Anim. sans Verteb.,' 1818, describes shortly the
few species previously made known to us. Amidst this
host of continental authors, no British zoologist appears,
with the exception of Dr. Leach. In his article " Crus-
taceology," in the 'Edinburgh Encyclopaedia,' 1814; in
his article " Annulosa," in the Supplement to the ' Encyc.
Britann.,' 1816 ; and still later, in the article " Entomos-
traca," in the 'Diet, des Scien. Nat.,' 1819, he describes
the genus, and introduces, apparently for the first time,
a British species.

.060 BRITISH ENTOMOSTRACA.

Of late years, much more has been done by the con-
tinental zoologists to extend our knowledge of these
curious little creatures. Otto, in the ' Nova Acta Natur.
Curios./ 1828, Burmeistcr, in the same work for 1831,
Kroyer, in his ' Tidsskrift,' 1838-9, and M. Edwards, in
the 'Ann. des Scien. Nat.,' 1833, and in his 'Hist. Nat.
dcs Crust.,' 1840, have given us a great deal of extremely
interesting information with regard to their habits, ex-
truded our knowledge as to the number of species, and
brought forward a variety of startling facts respecting the
young, and the curious changes of form they undergo in
i heir advance to maturity. In America, Pickering and
Dana have studied carefully a species found abundantly on
the com 111011 cod-fish of their coast ; and in a lengthened
memoir in the ' American Journal of Science' for J 838,
have given a most minute description of it, with abundant
anatomical details. They do not appear to have followed
up the hatching of the young animals ; but Mr. II.
Goodsir, in a paper in the 'Edin. Plrilos. Journal' for 1842,
has contributed somewhat to our knowledge concerning
the young of the common species found in Scotland.

si mi I null/ and Physiology, Sfc. — The Caligi are generally
of a more or less oval shape, and depressed. The body
of the animal consists of two principal portions. The
anterior, frequently much the larger, consists of an oval,
shield-shaped carapace or buckler, which includes the
head and greater portion of the thorax. The posterior,
sometimes not a fourth part the size of the other, com-
prises the remainder of the thorax and abdomen.

The anterior or cephalo-thoracic portion is formed of a
flexible coriaceous substance, usually transparent, and
composed, according to Pickering and Dana, of two coats.
On its fore part, which is obtusely rounded, we perceive a
narrow plate, notched in the centre, and its posterior por-
ti'tn has generally a deep sinus on each margin. The
dorsal Mirl'ace is marked by several lines or furrows, which
divide it into four distinct portions. These furrows arc

CALTGID.E. 201

considered by some authors* as imperfect articulations.
One on each side extends from the notch at the termina-
tion of the narrow frontal plate to the sinus at the posterior
part of the carapace, dividing it into two lateral segments,
while a third runs across the centre of the body, connect-
ing the other two, and forming an upper and a lower
central segment. The upper, or anterior, may be called
the cephalic, and the lower the thoracic region of the
carapace. The former contains, attached to it, the an-
tennae, eyes, organs of mouth, and foot-jaws ; the latter
the first three pairs of natatory feet.

The narrow plate, mentioned above as visible on the
anterior edge of the carapace, is sometimes very distinct,
and is prolonged laterally to a somewhat sharp point,
which is detached from the margin of the carapace, and
covers the insertion of the antennae. In tracing the parts
of these little creatures analogous to the parts belonging
to the higher Crustacea, we might consider this plate,
with its lateral prolongations, as the representative of the
first pair of antennae, here reduced to a single joint, and
inimoveably fixed to the carapace.

The real antennas, (t. XXXIV, f. 5 b], corresponding to
the second pair in the higher orders, are very short, and
composed of two joints. The basal joint is inserted upon
the edge of the carapace, immediately beneath the ter-
minal point of the frontal plate. It is flattened in shape,
and the upper edge is beset with short setae. The apical
joint is narrow, nearly cylindrical in form, about two thirds
of the length of the preceding, and is terminated by
several short hairs. In many of the species we perceive,
on the frontal plate, near its free extremity on each side,
and on the inferior surface, a remarkable organ (t. XXXIV,
f. 5 a], consisting of a thin, nearly circular membrane,
attached by its central portions, and in form of a cup,
approaching somewhat in appearance to the sucking-disc
of the Argulus. These were considered by Midler as the

* Pickering uiul Dana, loc. cit.

'2(\°2 NKITISII ENTOMOSTKACA.

rves of the animal. Later authors have proved this
opinion to be erroneous, and Pickering and Dana consider
them as true sucking-discs, by which the Caligi attach
tin 'iiiM-lvcs to the fishes upon which they live. 'They
assert, in proof of the correctness of this opinion, that they
have frequently tested the use of these organs by apply-
ing the blade of a knife to the inferior surface of the front
margin, while the animal was on its back, and that in
numerous instances it adhered so firmly to the knife, that
it was lifted up and carried to some distance. It exists,
however, only in some of the species, and its presence
or absence has been used by Nordmann as a generic
character.

The eyes are two in number, and are situated nearly in
the centre of the cephalic segment. They are small,
simple in structure, of an oval shape, and placed close to
each other. In the living animal they are of a red colour,
and are slightly projecting.

The mouth (t. XXXIV, f. 5/) is situated in the median
portion of this segment, the eyes being placed directly
over part of it. As in the Argulus, this organ consists
of a siphon, or conical sucking-tube, composed of two
long, slender, styliform organs, curved inwards, and armed
on their points with about twelve teeth. These represent
the mandibles, and they are inclosed in a sort of sheath,
formed from the union of the parts corresponding to the
upper and lower lip. Situated upon the sides of the
sucking-tube we perceive two pairs of rudimentary ap-
pendages (t. XXXIV, f. 5 d). The one, rising in front of
the other, consists of a small basilar joint, terminated by
a short, curved apex ; the other is more developed, and
is divided into two stout, terminating claws, directed
downwards. These constitute the analogues of the two
pairs of jaws in the other orders of Crustacea.*

l''"i- ;i Culler exposition of !his MihjrH, MT Ilic \cr\ infcmsfiiiLr mnnnir
n|' M Kil\\,-mls ii|H.ii the Or^ani/alinu of llir Month of (lie SijihonoMomu,
as r\rici|i!ilir(| li\ him in tlic r,/,,il,i,-its uliihix, in the 'Ann. do Sc. Nat.,'
xxviii, 1 "

CALIGID/E. 263

The parts corresponding to the foot-jaws are well de-
veloped. They are three pairs. The first pair (t. XXXIV,
f. 5 c) — the posterior antennae of Kroyer — is situate be-
tween the siphon and antenna}, and consists of two articu-
lations ; the basal broad and fleshy, the terminal tapering
to the extremity, which is in form of a strong hook.
At a little distance from, and external to, the extremity
of this joint, we see a stout, horny-looking, hooked spine,
springing from it. The second pair (t. XXXIV, f. 5 //)
is longer than the preceding, and consists of two articu-
lations ; the basal more slender than that of the first pair,
and the terminal still more so, of considerable length, and
ending in two or three falciform claws, the edges of which
are armed with small teeth. The third pair (t. XXXIV,
f. 5 i) is longer than the two preceding, though not
so long as the second. It is cheliform, and differs a
little in the two sexes. In the male, it consists of a
large, fleshy, basal joint, which has articulated to it a
stout claw, curved inwards, and having a small seta near
its apex. In the female, the basal joint is smaller, and
less fleshy, and the terminal is longer and larger than in
the male. These foot-jaws constitute real organs of pre-
hension, and it is by means of them that the animal
fastens itself upon its prey.

The true feet, or natatory feet, consist of four pairs,
three of which are attached to the thoracic segment of the
carapace, while the fourth springs from the penultimate
ring of the thorax. The first pan- (t. XXXIV, f. 5 ft) has
three articulations. The basal joint is of a cylindrical
form, and the second is similar in size and form, but with
numerous very short setae on under margin. The third,
or terminal, is about one half the size of the others, and
has on its inferior edge three long, finely-ciliated setae,
nearly as long as the preceding joint of the leg, and at
the apex four short, stout, naked setae. The second pair
(t. XXXIV, f. 5 /) is composed of two basilar joints, the
first short, and provided with a long ciliated seta on its
under surface ; the second very large, becoming broader

264 BRITISH ENTOMOSTRACA.

from l)ase to apex, and giving off two branches or rami,
each of three joints, provided with rather long, plumose
Betas. The first and second of these joints have each one
very long seta springing from their base, and the terminal
giving off at its apex six of nearly equal length. The
third pair (t. XXXIV, f. 5 m) is not unlike the preceding.
The basilar portion, however, seems to consist of only one
joint, which appears to constitute a lamellar appendage to
the lower part of the cephalo-thoracic portion of the body.
It gives off' two short rami, each single-jointed, and fur-
nished with plumose setse. On the edge of the lower
part of this portion of the body there is a short spine or
hook, similar to that observed near the first pair of foot-
jaws The fourth pair (t. XXXIV, f. 5w) springs from the
posterior thoracic segment of the body, and is very dif-
ferent from the preceding pairs, being more adapted for
the purpose of walking than swimming. It is slender,
elongated, and directed outwards ; consists of four joints,
and is simple, and not branched. The joints diminish
in size as they approach the apex, which is either in form
of a long, curved seta, with a row of short spines on its
inner edge, or a short joint terminating in three short seise.
On the median line of the body, between the last pair of
foot-jaws and first pair of feet, we observe a broadish
appendage (t. XXXIV, f. 5j?'), of a horny nature, generally
bifurcated, directed backwards, and capable of being
elevated or depressed. It is a sort of sternum. On the me-
dian line of last thoracic segment of the body, and toward
the posterior extremity, we see two somewhat similar
smaller horny tubercles, which M. Edwards considers
may be regarded as the vestiges of a fifth pair of feet.
I'Yom the external portion of the posterior part of this
segment also, on each side, in the female, we see the
e\i( Tiial ovaries, two long cylindrical tubes, sometimes
two or three times the length of the whole animal.

According to Pickering and Dana, the internal organs
of reproduction consist of a large pvrilbrm organ, of a
glandular appearance, situate just anterior to the stomach,

CALIGID/E. 265

and provided with a duct which extends through the
whole length of the thorax, and terminates, in the female,
in the ovarian tubes ; and in the male, in the genital
organs, situated in the same place as the external ovaries
in the female. They are thus analogous to the spermatic
glands in the one, and the internal ovaries in the other
sex.

The abdomen is generally very small, in proportion to
the rest of the body. It consists of only one joint, and
sends off from its posterior edge two plates, each furnished
with several pretty long plumose hairs or filaments.

The intestinal canal may be easily traced through the
parietes of the body, extending from the mouth through
the length of the thorax and abdomen to the anus, which
opens between the caudal appendages. It consists of
an oesophagus, stomach, and intestine. The muscular
system is well developed, and the muscles moving the
different members may be easily traced through the pel-
lucid skin.

The circulation of the blood is fully described by
Pickering and Dana. It seems to be wholly lacunal,
and consists of broad, irregular streams, passing through
the spaces left among the internal organs. No distinct
vessels have been discovered. The number of pulsations
has been found to vary from thirty to forty in a minute.

The Caligi are only found upon marine fishes. They
adhere to the body among the scales, by means of their
foot-jaws, and can quit the place they have chosen, and
move to another part of the fish. They are most fre-
quently, perhaps, found on the parietes of the mouth and
branchial cavities, but occur also indiscriminately on dif-
ferent portions of the body. Sometimes they occur in
great numbers, on the same fish. Pickering and Dana
tell us that they are found most numerous on half-grown
fishes, and that they have taken as many as forty specimens
from one individual. On the salmon I have observed
them in considerable numbers, and on various parts of
the fish. We notice both sexes on the same fish, though

266 BRITISH ENTOMOSTRAflA.

the females are the most abundant. Their habits arc
rather difficult to observe, as they generally die soon after
the fish upon which they live are taken out of the water.

Pickering and Dana introduced several individuals into
a glass of salt water, soon after the fish was caught, and
remarked that the greater portion of them sought the
surface, where they attached themselves to the sides of
the glass. Many quitted the water entirely, and crept
up the glass for an inch or two above the surface. In
doing so, they carry a portion of water with them, confined
under their broad carapace, the margin of which is closely
attached to the side of the vessel, and thus are enabled
to exist for some little time. They did not seem, however,
to make any attempt to return to the element they had
left, and died soon afterwards.

\Vhen living attached to the fish, should they be
touched or disturbed, they move with considerable ra-
pidity, and travel over the body of their host, moving
along with equal facility either backwards or forwards.
By means of their natatory or branchial feet, they swim
also with considerable rapidity, and no doubt occasionally
change from one fish to another, as Strom had long ago
observed. Their food does not seem to be exactly ascer-
tained. Strom asserts that they live by sucking the blood
from the fish, and says that he has seen that fluid flow
into the mouth of the Caligus, and thence through the
neck and whole body.

As Miiller justly remarks, however, with regard to
Strom's observations, they carry little weight with them,
for as he mistook the tail for the head, he must have
misunderstood the nature of what lie saw, and perhaps
taken the genital organs for the mouth. "I cannot
believe," he says, "that they suck the fishes, but it is
more probable, from their moving their branchial feet, as
all the rest of the Entomostraca, that they cause the water
In carry to their mouth the molecules floating in it, and
the mucus from the fish." O. Fabricius also says, that
(lie >peries lie describes nouiT>he> itself \\illl the mucous

CAL1G1DYE. 267

juices of the fish it lives upon. This opinion receives
continuation from the observations of Pickering and Dana
upon the species described by them, as they have never
detected any blood in the stomachs of those they have
dissected, though they have frequently opened them im-
mediately after taking them from the fish. The fluids in
the intestines were always of a light colour, and they
conclude that their food must consist of the mucus which
covers the body of the fish, a secretion which is natural
to it, and always abundant.

The Argulus and the Caligi are generally found most
abundant on weak and diseased fishes. It does not
follow however, from this, that the fish is rendered weak
or diseased by the attacks of these parasites, but that
being previously weakened by wounds or disease, it is
less able to avoid them, and more incapable of clearing
itself of them.

The Caligi change their skin, as well as the other
Entomostraca, but respecting the process little as yet is
known. Pickering and Dana, to whom I have so fre-
quently referred, inform us, that as the time for throwing
off" the old skin approaches, the internal membrane, which
is destined to form the new envelope, and which may in
some species be seen through the outer shell, is observed
to be folded variously into small ridges, over the whole
body of the animal, which ridges or folds continue to in-
crease in size as the time for moulting approaches. These
folds, they remark, evidently result from the animal in-
creasing in size, within a shell which has become too small
to admit of its expansion. Nothing seems known with
regard to their method of copulating. Tilesius, indeed,
asserts that he has witnessed the act. He says he has
seen two individuals adhering for days together, the thorax
of the one fixed to the abdomen of the other. But that
what he had seen was a true act of copulation is doubtful,
for he attempts to prove that the Caligus productus, Mull,
(which is now ascertained to belong to a different genus
even), and the curtus, Mull., are the same species, the

208 BRITISH ENTOMOSTRACA.

former being the female and the latter the male ; and it
was these two different species that he had observed, as
he imagined, in the act of copulation.

Tilesius and others have doubted whether the long
filaments attached to the posterior extremity of the thorax
were really ovaries. This is now clearly ascertained to
be the fact. They contain a great number of eggs, which
are round, and disposed in one single row, and even
young females are found, as is the case with other Ento-
mostraca, to possess external ovaries filled with eggs.
The young, when first hatched, are very different in ap-
pearance to the adult. In form they resemble closely the
young of the Cyclopidae, and, like them, undergo a series
of changes of skin, or moultings, before they assume the
completely-developed form of the parent animal.

This family contains four British genera — Caligus,
Lepeoptheirus, Chalimus, and Trebius.

1. CALIGUS. — Fourth pair of feet slender, of only one
branch, and serving the animal for walking. A pair of
small Innnles or sucking-discs on the lower surface of the
frontal plates.

2. LEPEOPTHEIRUS. — Fourth pair of feet as in Caligus.
Frontal plates destitute of the kmules or small sucking-
discs.

3. CHALIMUS. — Feet as in two preceding genera.
Frontal plate provided with a long and slender appendage
adapted for prehension, arising from the centre of its an-
terior surface.

4. TREBIUS. — Fourth pair of feet slender, and divided
into two branches, adapted for swimming. No lunules
or sucking-discs on frontal plates.

CALIGUS. 209

Genus 1 — CALIGUS.

CALIGUS, Wilier, Entomostraca.

— Latreille, Cuvier, Lamarck, Leach, Desmarest, Nordmann, ,^ ^^'^

M. Edwards, Pickering and Dana, Kroyer, 8fc.
MONOCULUS, Linnmis, Fabricins, Manuel.
BINOCULUS, 0. Fabricius, Faun. Green.
Miiller, Zool. Dan. Prod.
PEDICULUS, Easier, Opusc. Subscciv.

Strom, Phys. og Oeconom. Besk.
ONISCUS, Slabber.

Character. — Fourth pair of feet slender, of only one
branch, and serving the insect for walking. Thorax ex-
hibiting only two distinct articulations. Frontal plates
possessing a small sucking-disc or lunule on the under
surface of each lateral portion.

1. CALIGUS DIAPHANUS. Tab. XXXII, fig. 1.

CALIGUS DIAPHANUS, Nordmann, Microgr. Beitr., ii, 26.
Kroyer, Tidsskrift, i, 623, t. 6, f. 5.
M. Edwards, Hist. Nat. Crust., iii, 452, No. 5.
Thompson, Ann. Nat. Hist., xx, 247.
Baster, Op. Subsec., ii, t. 8, f. 9 B (?).

Description. — Male. Carapace large, and nearly round;
frontal plate of considerable size ; lunules distinct but
not large. Antennae of moderate size ; basal joint large,
and setiferous on external edge. Thorax very much
smaller than carapace. Penultimate segment very small
and narrow ; the last somewhat lunulate, the external
posterior angles terminating in a projecting lobe, which
is shortly bifurcated, the external fork giving off one,
and the internal two, short plumose setae.

Abdomen nearly as long, but narrower than the last
joint of thorax, and terminating in two pretty large caudal

270 BRITISH ENTOMOSTRACA.

plates, each sending off three long and one short plumose
setae. Third pair of foot-jaws very large. Sternal fork
small, with simple branches. Fourth pair of feet termi-
nating in one long curved spine or claw, serrated on its
inner edge, and one or two short ones at its base. Ap-
pendages at inferior portion of last articulation of the
thorax slender, simple.

1 1 all. — Belfast Bay, W. Thompson, Esq. Taken from
the turbot in March, July, and December ; from the 7 V/V//V/
pini (gurnard), the mackerel, and Lota molva in March
and October ; from the Merlangus carbon arius in March ;
the Pat/i'll a* centrodontus in October ; and the plaice in
March, October, and December; the codfish in January;
and the halibut in March. British Museum.

2. CALIGUS RAPAX. Tab. XXXII, figs. 2, 3.

CALIGUS HAPAX, M. Edwards, Hist. Nat. Crust., iii, 453, No. (>,
t. 38, f. 9.

Description. — Female. Carapace oval, considerably
longer than broad, narrower at upper extremity, and broad
posteriorly. Frontal plates prominent, and very large for
the size of the animal, nearly straight in centre, or but
very slightly notched. Lunulcs large. Antenna* also
exceedingly large for the size of the animal, the basal
joint broad, and armed with ten plumose hairs or seta?
on its upper edge ; the terminal joint long, nearly the
length of the basal joint, and furnished at its extremity
with five or six sharp setae.

Thorax not quite so long as carapace, and much
narrower; last joint obovate or pyriform, and slightly
lobed at the posterior extremity on each side. Abdo-
men about two thirds the size of the thorax; longer than
broad.

Caudal plates of considerable size, and terminated by
three stout, long, and one short, plumose seta?. Sternal
fork with simple, sharp-pointed branches. l;oiirlh pair

CALIGUS. 271

of feet long and slender ; the last joint terminating in a
long curved claw, serrated on its inner edge, and two or
three short spines at its base. Oviferous tubes nearly
the length of the body.

Male. In the male, the last joint of the thorax is
considerably smaller, and more of an ovoid shape, than
in the female; while the abdomen is longer, narrower,
and divided into two articulations, the first being the
shorter. The terminating setae are long, and densely
plumose.

Third pair of foot-jaws large. In other respects much
the same as female, but rather smaller.

This species strongly resembles the C. minimus of
Otto ; but there is no notch on frontal plates ; the sides
of the carapace are not hairy, and the antennae are diffe-
rent, being much larger.

Hah. — Belfast Bay, W. Thompson, Esq. Taken from
the gurnard (Trigla kirundo etpini), November 1839 ; the
Zeusfaber, in February; Trigla gurnardus, June; Platessa
limanda, December ; Lough Neagh trout, March ; Corre-
gonus pollan, Lough Neagh, November and December ;
the brett, Rhombus vulgaris, March, November, and De-
cember ; Merlangus vulgaris, March and December.

2. CALIGUS MULLEBI. Tab. XXXII, figs. 4, 5.

CALIGUS MULLEKI, Leach, Enc. Brit. Supp., \, t. 20, f. 1-8.

Desmarest, Coiis. gen. Crust., t. 50, f. 4;a-e.

Description. — Female. Carapace oval, rather longer
than broad, narrower at upper extremity. Frontal plates
of considerable size, notched in the centre. Lunules well
developed. Antennae of considerable size; basal joint
large. Thorax shorter than the carapace, about half the
size ; penultimate joint very small, of an elongate
diamond shape ; last joint nearly quadrilateral, and lobed
at posterior extremity. On each lobe there are two very
small tubercles, each of which gives off two short setae.

272 BRITISH ENTOMOSTRACA.

Abdomen very short and rounded, broader than long.
Caudal plates terminated by three tolerably long, plu-
mose setae. Sternal fork with simple, short, obtuse
branches. Second pair of foot-jaws very long ; the last
joint being narrow, long, and terminated by two curved
claws, one longer than the other. Fourth pair of legs
stout ; the first joint broad and thick, the last ending in
one long, stout, curved claw, which is serrated on its
inner edge, and two short ones. Ovifcrous tubes of
considerable length.

Male. In the male the last joint of thorax is consider-
ably smaller than in the female, and more rounded ; the
lobes much sharper, and terminated by the same tubercles,
but of a larger size. Abdomen about two thirds the
size of the last joint of thorax. Second pair of foot-jaws
large.

Hal). — Belfast Bay, W. Thompson, Esq. Taken from
the cod and brill, February, March, November, and De-
cember; Merlangus poll add us, March 1840; the brett
(Rhombus vnlyaris}, March, November, December, 1837 ;
Mrr/a/if/us vulyaris, Flem., March, December, 1837 ;
Corregomts jpollan, Lough Neagh, November and Decem-
ber 1837 ; Gad us cegelfinw, December 1837 ; the plaice,
Belfast, February 1844; Mngil chelo, Belfast, April
1840.

4. CALIGUS CENTRODONTI. Tab. XXXII, figs. G, 7.

Female. Carapace obovate ; very much narrower in
front than posteriorly. Frontal plates well developed,
deeply notched in the centre. Lunules large, and nearly
round. Basal joint of antennrc large.

Thorax much smaller than carapace ; last joint quadran-
gular-shaped, narrow superiorly where it articulates with
penultimate joint, and crescentic at inferior edge ; nearly
as brojul as long; at each angle inferior ly giving ofi' a
small tubercle, ;inned with two seta1.

LEPEOPTHEIRUS. 273

Abdomen exceedingly small ; completely concealed by
the ovarian tubes when filled with ova ; of a somewhat
square shape, and terminating in two rounded caudal
lobes, each of which gives off four short, plumose setse.
Sternal fork well developed, with simple, stout, and sharp-
pointed branches. Fourth pair of feet short and stout.
Ovarian tubes nearly of the length of the whole body.

Male. Carapace as in female, but much larger in pro-
portion to the size of the whole animal. Thorax much
smaller; more completely quadrangular in shape, and
more deeply crescentic on lower margin ; broader than
long ; the inferior angles more acute, and giving off three
short, stout setae at a little distance from each other.

Abdomen very small, in shape of a half circle, the
lower margin straight. Caudal segments large in pro-
portion, oval, curved inwards, and giving off five stout,
plumose setse, the three internal ones the longest. The
second pair of foot-jaws is very large.

Hab. — Taken from the tail and fins of the Pagcttus
centrodonti, October 29th, 1837; Dublin, Dr. Bellingham,
W. Thompson, Esq.

Genus 2 — LEPEOPTHEIRUS.*

LEPEOPTHEIETJS, Nordmann, Microgr. Beit., ii, 28.
CALIGUS ( pars), Kroyer, M. Edwards, Elainville, Cuvier.

Character. — Fourth pair of feet slender, of only one
branch, and serving the animal for walking. Thorax
exhibiting only two distinct articulations. Frontal plates
destitute of the small sucking-discs or lunules, on their
under surface.

* From XtTTot-, a scab; and <t>0np, a louse.

18

274 BRITISH ENTOMOSTRACA.

1. LEPEOPTHEIRUS STROMII. Tab. XXXII, figs. 8, 9.

CALIGTJS STROMII, Baird, Trans. Bcrw. Nat. Club, 1847.

LAXE LUUS, Strom, Kiobeuhavn. Selsk. Skrift., x, 23, t. 7, f. 1-7.

CALIGUS VESPA, Ecltr. Thompson, Ann. and Mag. Nat. Hist., xx, 248.

Description. — Fanalc. Carapace oval. The frontal
plates not very prominent. Thorax about the same length
as carapace ; last articulation narrower at upper extremity,
broad posteriorly, and terminating in two rounded lobes.
Abdomen long and narrow, nearly as long as the last joint
of thorax. Caudal plates of moderate size, and giving off
several stout, short, plumose setae. Sternal fork short,
with simple branches. The horny tubercles on the median
line of posterior portion of thorax large, and simple.
Oviferous tubes long, three or four times the length of the
animal. Length of body (exclusive of tubes) about half
an inch.

Mah. The male is much smaller than the female. The
carapace is oval, and much longer in proportion to the
thorax than in the female ; thorax oval-shaped, narrow,
and notched rather than lobed posteriorly ; the outer
angles in form of a small protuberance, and armed with
two or three short setae. Abdomen much shorter than in
female ; terminal setae of caudal appendages longer and
finely plumose.

This species approaches very nearly the description of
the Cnti(/»x vespa of M. Edwards. The vespa, however,
is only three lines in length, and has the carapace narrow
in front, and very broad posteriorly, and is as broad as
long, while in this species the carapace is almost an exact
oval, and the animal is half an inch in length. In rrxpa,
the horny tubercle at the base of the thorax is small and
-i lif'erous; and in this species it is simple, and of consi-
derable si/r.

i. — Henvick -Bay; taken oft' the salmon, August
\, \V. B. Salmon at Henvick, Dr. Johnston. County
Down, ofT the Mi/iim 1rvtt<i, August; Salwo salar, July;

LEPEOPTHEIRUS. 275

Salmo criocV, December. Off a salmon, at a salmon-
leap on the river Bush, near Giant's Causeway, June
1837; and at Cushendale, April.* From the sea-trout,
Donaghadee, April ; f W. Thompson, Esq.

2. LEPEOPTHEIRUS PECTORALIS. Tab. XXXII, fig. 10.

LERN^EA PECTORALIS, Miiller, Zool. Dan. i, 41, t. 33, f. 7 ; En-
cyclop, method., Vers, t. 78, f. 12.
CALIGUS PECTOEALIS, Kroyer, Tidsskrift, ii, 8, t. 6, f. 4.

M. Edwards, Hist. Nat. Crust., iii, 454, No. 9.

Thompson, Ann. and Mag. Nat. Hist., xx, 247-
LEPEOPTHEIRTJS PECTORAXIS, Nordmann, Mikr. Beitr., ii, 30.
PECTORAL LERN^EA, Shaw, Nat. Miscell., viii, t. 295.

Description. — Female. Carapace oval. Frontal plates
small, notched in centre. Antennae small. Thorax fully
as long as carapace. Penultimate joint very narrow ; last
joint nearly as large as carapace ; almost quadrilateral,
and slightly lobed at posterior extremity. Abdomen short.
Caudal plates small ; terminal setae short. Sternal fork,
with simple, sharp-pointed branches. Third pair of foot-
jaws large. Fourth pair of feet small.

Hab. — Belfast Bay, W. Thompson, Esq. Off the floun-
der, John-dory, mackerel, dab, and sole, in March. The
gemmous dragonet (Cattionymus tyro), W. Yarrell, Esq.

3. LEPEOPTHEIRUS NORDMANNII. Tab. XXXIII, fig. 1.

CALIGUS NORDMANNII, M. Edwards, Hist. Nat. Crust., iii, 455, No. 10;

Atlas Regne An. de Cuv., edit. Crochart,
Crustac., t. 77, f. 1.
Thompson, Ann. Mag. Nat. Hist., xx, 248.

Description.— -Female. Carapace rounded oval, nearly
as broad as long, diaphanous. Frontal plates of consi-

* Amongst these specimens were two or three males, and in oiie instance
the male was firmly attached to the female by his strong third pair of foot-
jaws.

f Some of these specimens were of a reddish hue, and shone with a metallic
lustre.

•21 (') BRITISH ENTOMOSTKACA.

del-able size, rather prominent in centre, and not notched.
Antennae of moderate size. Thorax much shorter than
carapace, narrow. Penultimate joint small ; last joint
rather longer than broad, obcordate, and deeply lobed
at posterior extremity. Abdomen short. Caudal plates
small; terminal setae of moderate length and plumose.
Sternal fork well developed, with long, simple, slender,
sharp-pointed branches. Oviferous tubes long and slender.
.Males not seen.

Hah. — Found on Orthagoriscm molce ; taken on County
Antrim coast, September 1848, W. Thompson, Esq.

4. LEPEOPTIIEIRUS HIPPOGLOSSI. Tab. XXXII, fig. 1 2.

CALIGUS HIPPOGLOSSI, Kroycr, Tidsskrift, i, 625, t. 6, f. 3.

3L EJtcafds, Hist. Nat. Crust, iii, 456, No. H.
BINOCULUS pisrixrs, 0. Fabricius, Faun. Greenland., 239.

Description. — Female. Carapace large and rounded,
deeply lobed on each side. Frontal plates of moderate
size. Antennae of considerable size, setiferous on edge
and at extremity. Thorax about two thirds the length of

O

the carapace, and much narrower ; last joint elongate,
quadrilateral, slightly lobed at each terminal angle. Ab-
domen very short. Caudal plates very small, and giving
off four short, plumose setae from each. Sternal fork
twice bipartite; the branches of second fork short and
truncate. Oviferous tubes rather longer than the body.
The whole animal is beautifully marked with pink or red
spots, distributed in an irregular pattern over the whole
carapace, thorax, abdomen, and outer surface of fourth pair
of legs. It is the most beautiful species I ha\e seen ; but
the colours fade and disappear in spirits. Specimens
of this elegant creature were sent several years ago by
Dr. Johnston of Berwick to Mr. Westwood, who at that
time \\as engaged upon the Crustacea, but they were not
dexTiI.ed. Since then the species has been described by
KIOMT.

LEPEOPTI1EIRUS. 277

lla /A- -Taken from flic halibut, in Berwick Bay;
Dr. Johnston.*

5. LEPEOPTHEIRUS OBSCUKUS. Tab. XXXII, fig. 11.

Carapace large, rounded oval. Frontal plates well-
developed. Antennae of considerable size, terminal arti-
culation giving off at the apex eight or ten short setae.
Thorax very much smaller than carapace. Last articula-
tion rounded on upper portion, and square at inferior
part ; laterally giving off, on each side, two sharp lobes,
one situated immediately above the other, and armed with
three rather long, plumose setae.

Abdomen small ; not more than one third the size of
last ring of thorax, square-shaped ; the centre of lower
margin a little produced, and forming two very small
lobes. Caudal plates stout, and giving off four long,
finely-plumose setae, the outer of which is the shortest.
Sternal fork well developed, each branch being bifurcated ;
the inner branch being much smaller than the outer. The
fourth pair of feet is very long and stout, extending,
when stretched out, to fully the length of the thorax and
abdomen together. The first joint is large, and the last
terminates in three curved spines, the penultimate joint
giving off one also.

Hab. — The brill, taken in Belfast Bay, February and
March 1844 ; W. Thompson, Esq.

* I am indebted to my much-valued friend Dr. Johnstou, for very fine
specimens of this pretty species, and for many other proofs of kindness
during the time I have been preparing this monograph. I am glad of the
opportunity thus afforded me of bearing testimony to his uniform attention
and unvarying friendship.

278 BRITISH KNTOMOSTRACA.

G. LEPEOPTHEIRUS THOMPSONI. Tab. XXXIII, fig. ~.

Female. Carapace round. Frontal plates small. An-
tenna) well developed. Thorax about the fourth part the
size of the carapace. Penultimate segment very small. The
last nearly quadrilateral ; the posterior edge deeply lobed.

Abdomen long ; the length of the thorax ; upper por-
tion narrow, and bulging out as it approaches the tail.
Caudal plates short, rather broad, and giving off three
long, plumose seta?, and two shorter ones. Sternal fork
with sharp, simple branches.

Male. — Carapace round, but rather broader than in
female. Thorax and abdomen both considerably shorter
than in female.

7/«#.- -Taken from the turbot, March 1837, along with
Call ff us Miillcri and C. diaplianus ; W. Thompson, Esq.

Genus 3 — CHALIMUS.

CHALIMUS, Bvrmeister, Nov. Act. Acad. Nat. Cur. Bonn., xvii.
M. fidicards, Hist. Nat. Crust., iii.
Kroi/er, Tidsskrift, ii.

C/itn-acter. — Feet, as in preceding genera. Thorax
exhibiting four distinct segments. Frontal plates without
lunules, or sucking-discs, but provided with a long and
slender appendage adapted for prehension, arising from
the centre of its anterior surface.

The genus Chalimus was first established by Burmeister
in the 'Nov. Act. Acad. Nat. Cur. Bonn.,' in 1835, to
receive a small animal, closely allied to, and nearly
resembling the Caligi, but possessing a long and slender
appendage arising from the centre ul' the frontal plates, by
which it fixes itself to its prey, lie found it attached to
a mackerel; but Kroyer afterwards discovered the same
^pccies adhering to a Caligus ; and the only specimen I
have yet met with, I found also parasitic upon an indivi-
dual of that

CHALIMU8. 279

Kroyer seems disposed to consider it merely as the
young of a Caligus, but farther observations are necessary
to confirm this. The general appearance is that of a
Lepeoptheirus ; but we can trace four distinct articulations
in the thorax, and three in the abdomen.

The frontal plates are well developed, and want the
small lunules or sucking- discs on the lateral portions ;
but instead of these, have arising from the central part of
its anterior margin a long and slender organ, rather in-
distinctly articulated at its base, and terminated by a
round expansion like a sucker, by which it fastens itself
to the body to which it is found attached. The presence
of this organ would lead us to suppose that this animal
must lead a much more sedentary life than the rest of the
Caligida3 ; and it would appear in this respect to connect
it with some of the Lerneada3, which we shall find to
possess a somewhat similar organ of prehension.

1. CHALIMUS SCOMBRI. Tab. XXXIII, figs. 5, 5 «, b.

CHALIMUS SCOMBRI, Burmeister, Nov. Act. Acad. Nat. Cur. Bonn.,

xvii, 294, t. 23, f. 13.
Kroyer, Tidsskrift, ii, t. 1, f. 1.
M. Edwards, Hist. Nat. Crust., iii, 457.

Description. — Carapace elongated oval, somewhat nar-
rower at the anterior extremity, and then gradually
becoming broader posteriorly. Frontal plates large, well-
developed, and prominent. Thorax composed of four
distinct segments. Abdomen large, and consisting of
three joints ; the last terminated by two tolerably-sized
caudal plates, each sending off three or four short seta3.

Hab. — Belfast Bay, attached to a Caligus Mutteri,
W. Thompson, Esq.

280 BRITISH ENTOMOSTRACA.

Genus 4 — TREBIUS.

TREBIUS, /\"/w//w, Tidsskrift.

M. Edwards, Hist. Nat. Crust.

muit, Ann. aud Mag. Nat. Hist.

Character. — Fourth pair of feet slender, and divided
into two branches, adapted for swimming. Thorax pos-
sessed of three distinct articulations. Frontal plates
destitute of small sucking-discs or lunules.

1. TREBIUS CAUDATUS. Tab. XXXIII, figs. 3, 4.

TREBIUS CAUDATUS, Kroyer, Tidsskrift, ii, 30, t. 1, f. 4.

.]/. /V///V//Y/.S, Hist. Nat. Crust., iii, 458.
Thompson, Ann. and Mag. Nat. Hist., xx, 248.

Description. — Female. Carapace nearly oval, rather
longer than broad. Frontal plates of considerable size.

Antenna? well developed ; setae on external edge of basal
joint plumose.

Thorax narrow on first two joints, especially on second ;
last nearly quadrilateral, a little narrower at upper extre-
mity than lower, which is nearly straight on the edge.

Abdomen long and narrow, nearly as long as the thorax,
slightly narrowed towards the centre, and terminated by
two small caudal appendages, which give off three long and
one short plumose setae. Sternal fork with simple branches.

First pair of foot-jaws larger than in any of the Caligi,
and strongly hooked at their apex. Third pair much
-mailer. Fourth pair of feet short, with basal joint broad,
and the two terminating articulations short, oval, and fur-
nished with several rather stout setae. Ovifcrous tubes
short, and rather broad.

Male. The male is much smaller than the female. Cara-
pace broader.

Thorax, two first segments of much the same form as
in the female : last joint somewhat hexagonal.

PANDARID.E. 281

Abdomen shorter and broader than in the female, and
divided into two articulations, the last of which gives off
two caudal appendages, considerably larger than those of
the female, and armed at their extremity with the same
number of, but longer, plumose setae.

Antennas, foot-jaws, and feet as in female.

Hob.— Belfast Bay ; W. Thompson, Esq. Taken off
the Raia bat is, or skate, September 1838.

Family PANDABIM.

PANDABIENS (pars'}, M. Edwards, Hist. Nat. Crust., iii, 461.
CALIGID^E, RACE in (pars), ZeacA,Dict. Sc. Nat., xiv.
PANCAKING, Dana, Proc. Amer. Acad.

Character. — Head in form of a small buckler, provided
with frontal plates. A series of one or more pairs of
lamellar appendages, like the elytra of many insects, ex-
tend along the dorsal surface of the thorax. Oviferous
tubes straight, external.

This family contains only two British genera.

1. DTNEMOURA. — Elytraform appendages, one pair.
Three first pairs of feet setiferous ; the posterior foliaceous
and membranous.

2. PANDARUS. — Elytraform appendages, several pairs.
All the feet fitted to a certain extent for walking, and
armed near their extremities with short, thick hooks.

282 BRITISH ENTOMOSTRACA.

Genus 1 — DINEMOURA.*

DINEMOTTRA, Latreille, Cuv. Kegnc Anira., iv, 197.

M. Edteards, Hist. Nat. Crust., iii.
DINEMTRA, Nordmann, Mikrog. Beitr.
DINEMATURA, Burmeister, Nov. Act. Acad. Nat. Cur., xvii.

Dana, Proc. Am. Acad. Arts and Sc. 1849, p. 60.
PANDARUS, M. Edwards, Arm. Sc. Nat., xxviii.

Johnston, Loudou's Mag. Nat. Hist., viii.

Character. — Lamellar elytraform appendages covering
the thorax, only one pair. Three first pairs of feet seti-
ferous ; the posterior foliaceous and membranous.

Bibliographical History. — A species of this genus is
figured by Herbst, in the Berlin ' Gesellach. Skrift./ 1780,
and described under the name of " See-laus vom Hemor-
fisch ;" but the genus was first established by M. Latreille
(Cuv. Regne An., iv, 1829), to receive the species of
Caligus described by Miiller under the name of Caligus
productus. It was not remarkably well characterised or
defined, being taken from the figure merely of that species,
as given by Miiller • but it has been adopted by succeed-
ing naturalists to a greater or less extent, and latterly
more distinctly defined and limited by M. Edwards, in his
' Hist. Nat. Crust.' Burmeister, in the ' Nov. Act. Acad.
Nat. Cur.,' xvii, objected to the name, and proposed that
of Dinematura, as being more euphonious and more
grammatically constructed. .Judging, however, from his
figures and descriptions, it is evident that his genus
Dinematura is quite different from the Dincmoura of
Latreille, taking the CaHytt* /)r»<//trl//s as the type ; and
as M. Edwards very properly points out (1. c. iii, 4G3,
note), it is synonymous with the genus Nogaus of Leach,
already well defined by that author several years previously.
M. Edwards, in adopting this genus, as distinct from
Pandarus of Leach, points out distinct generic characters,
and sets it upon a better foundation than had heretofore

i two; • »//««, n tin ta.l, and oi//9o, a tail.

D1NEMOURA. 283

been done. Dr. Johnston has described two species be-
longing to this restricted genus, but under the name of
Paiidarus, both of which species were taken at Berwick-
upon-Tweed.

Anatomy. — The body of the animals belonging to this
genus is of an oblong shape, resembling considerably that
of the Caligidae, and divisible, as in them, into head,
thorax, and abdomen.

The cephalo- thorax, including the head and the first
ring of the thorax, is in form of a shield or buckler, and
somewhat of the same form and sculpture as in the
Caligida?, being divided into several distinct portions, as
in them, by deep furrows. The thorax is longer and
narrower than the carapace.

The articulations are very indistinct ; but M. Edwards
enumerates five. The first is confounded with the head,
and the second and third are small, and so united to-
gether as to appear only one. It is of a quadrilateral
form, and occupies the space left by the deep notch in the
posterior part of the carapace. The fourth segment is
about the size of the two preceding, but has attached to
it two large moveable plates, which cover the whole arti-
culation, and extend, like the elytra of insects, over part
of the succeeding joint also. The fifth or last ring is the
largest of all, and extends beyond the abdomen, nearly
concealing it altogether. It terminates posteriorly in two
rounded lobes, which have a deep notch between them, in
which is seen the abdomen. This part of the body is
small, of a square shape, and has appended to its ex-
tremity two caudal appendages, slightly ciliated on the
lower margin, and varying in size in the two sexes. In
the female they are much smaller than in the male, and
she has tAvo long oviferous tubes, such as the Caligi pos-
sess, much longer than the whole body of the animal, and
arising near the posterior edge of the last segment of the
thorax. The anterior portion of the carapace possesses,
like the Caligidae, the small, narrow, transverse frontal

BRITISH ENTOMOSTRACA.

plates, and springing immediately from beneath their
terminal point, we see the antennas. These are very
small, and consist of two short, simple articulations.

The structure of the mouth is also very similar to that
of the Caligidae, consisting of a sucking-tube, inclosed
within a sheath, and one pair of rudimentary organs at-
tached to its sides, equivalent to the jaws. The slyl.e of
the sucking-tube is longer and more slender than in
Caligus, and there is only one pair of rudimentary organs,
representing the first pair of jaws, the smaller and more
external pair being wanting. The foot-jaws are three
pairs. The first differ from the corresponding pair of the
Caligidae, in having at their base a large fleshy-looking
lobe, and in wanting the horny-looking, hooked spine
which springs from near its base. The second and third
are similar in structure to the corresponding pairs of the
Caligi ; but we see no trace of what has been described in
them as the sternum.

The feet are four pairs, and are attached to the different
segments of the thorax. The three first pairs are short,
divided into two stalks, each consisting of two or three
flat joints, which are beset with short cilia. The basilar
joint in each foot, from which the two stalks spring, shows
much the same form as that in the Caligi. The fourth
pair of feet differs from the others considerably. Instead
of the two stalks being small, jointed, and armed with
setae, they are each of only one joint, and that large, mem-
branous, of an oval shape, and not possessing any setae or
hairs on their margin at all.

On the under surface of the last segment of the thorax,
very near where it articulates with the abdomen, there is
a small forked, horny body, which M. Kdwards considers
as a rudimentary fifth pair of feet.

DINEMOURA. 285

1. DINEMOUIIA ALATA. Tab. XXXIII, figs. G, 7.

PANDAKUS ALATUS, M. Edtcards, Ann. Sc. Nat., xxviii, t. 8.

Johnston, London's Mag. Nat. Hist., viii, 203,

f. M a, b.

DINEMATURA ALATA, Burmeister, Nov. Act. Acad. Nat. Cur., xviii, 331 .
DINEMOURA ALATA, M. Edwards, Hist. Nat. Crust , iii, 464.

Description. — Body oblong, about half an inch in length
and two tenths of an inch broad.

Cephalo-thorax squarely rounded ; slightly notched in
front. Dorsal plates, or elytra, convex and smooth, about
the same breadth behind as in front, and occupying about
a third of the length of the whole body. Their posterior
margin is cut even, but obliquely. They are of a ches-
nut colour, very faintly scored, and marked with pale,
scattered dots. The under surface of the body is of a
dead white.

The last segment of the thorax is nearly of the same
length as the elytra, and has at its extremity a small,
horny tooth.

The caudal appendages of abdomen scarcely project be-
yond the last segment of the thorax. They are broad and
somewhat square-shaped in the male ; longer and narrow
in the female, and have at their extremities several short
setae.

This species was taken by Dr. Johnston from a Beau-
maris shark, in Berwick Bay, in 1834 ; and he observes,
that it " appears parasitical on several species of fish. It
generally attaches itself to the sides of the branchial covers,
adhering tenaciously, by thrusting the claws of the first
and third pairs of feet* through the skin."

Hab. — Beaumaris shark, Berwick Bay; Dr. Johnston.

* Foot-jaws.

286 BRITISH ENTOMOSTRACA.

2. DINEMOURA LAMN^E. Tab. XXXIII, fig. 8.

PANDARUS LAMN^E, Johnston, Loudou's Mag. Nat. Hist., viii, 204,

f. 22 a, b.

SEELAUS VOM HEMOKFISCH, Herbst, Berlin Gesellsch. Skrift., i, t. 3,

f. 1-8.

Description. — Body linear oblong. Cephalo- thorax
round, slightly notched in front, convex dorsally, and of
a pale colour, with a brown blotch in front.

Do^zrJ plates, or elytra, much smaller in proportion than
in preceding species ; narrower, and occupying only about
a fifth of the length of the body ; oval, smooth, rounded
at their posterior margin, and of a uniform pale colour.

The last segment of thorax is long and narrow, about
twice the length of the elytra, and rounded at the posterior
extremity. The centre of the upper part is marked with
a long, black spot.

Caudal appendages of abdomen large, oblong, and
giving off four stout, plumose spines. Oviferous tubes
long, more than twice the length of the whole body.

Hob. — Taken from a Beaumaris shark (Lamna Mo-
nensis], in Berwick Bay, September 1834 ; Dr. Johnston.

Genus 2 —PANDARUS.

PANDARUS, Leach, Latreille, Desmarest, Say, Bwmeister, Kroyer,

M. Edwards, Dana.
CALIGUS (sp.), Lamarck.

Character. — Lamellar elytraform appendages, several
pairs in number. All the feet fitted, to a certain extent,
for walking, and armed near their extremities with short,
thick hooks.

Bibliographical History. — This genus was first esta-
blished by Dr. Leach, in the Supplement to the ' Ency-
clopedia Britannica/ in 1816, and afterwards in the
' Diet, des Sc. Nat.,' 1819. He described several species

PANDARUS. 287

belonging to the genus, two of which are British. Since
then the genus has been adopted by Latreille, Desrnarest,
Kroyer, M. Edwards, &c., and several new species added
to it.

Anatomy. — The body of the animals belonging to this
genus is of an irregular oval form. The head is much
narrower than in the preceding genus, and we see none
of the furrows in the cephalo-thorax which are so well
marked in the Dinemoura? and Caligidse. The frontal
plates, however, are more largely developed, especially
laterally, where they are of considerable breadth, though
contracted in the centre.

The thorax is divided into four distinct segments, though
the first is concealed under the head, and is so closely
articulated with the second as to be confounded with it.
Each of these segments has attached to it one or two
lamellar appendages, extending downwards, and mutually
covering each other. Those of the first segment are a
pair, and are situated at the sides of the thorax, leaving a
space between them, which is occupied by the second joint.
This joint gives origin to another elytraforui appendage,
which is single, but deeply notched in the middle. The
third segment has a similar appendage, but much larger,
extending across the body, and deeply notched in the
centre also. The last ring has no appendage attached to
it, but it is of considerable size.

The abdomen consists of two segments. The first is
concealed under the second, and has attached to it on each
side a small appendage, toothed on the inner edge. These
are considered by M. Edwards as equivalent to the caudal
appendages. The second is the larger of the two.

The antennae are very small, as in the last genus, but
have near their base a small, fleshy, projecting lobe ; and
the mouth-apparatus resembles closely that of Dinemoura
also. The foot-jaws are short, and do not differ in struc-
ture from those of Dinemoura. There is no sternum.

The feet are four pairs ; they are all composed of two

288 BRITISH ENTOMOSTRACA.

branches. The first three pairs are each composed of two
joints, all of which are armed at their extremities with a
series of short sharp hooks. The last pair has only one
joint to each branch, and the outer branch alone has the
hooks. These hooks are evidently useful to the animal in
moving or walking, by enabling it to attach itself to the
bodies upon which it creeps. The oviferous tubes take
their origin from the last thoracic segment, though at first
sight they appear to spring from the last abdominal ring.

1. PANDARUS BICOLOR. Tab. XXXIII, fig. 10.

PANDARUS BICOLOR, Leach, Encyc. Brit. Supp., i, 405, t. 20, f. 1, 2 ;

Diet, des Sc. Nat., siv, 535.

Desmarest, Cons. geii. Crust., 339. t. 5, f. 5.

M. Edicards, Hist. Nat. Crust., iii, 470.

Bitrmeister, Nov. Act. Acad. Nat. Cur., xviii,331.

Kroyer, Tidsskrift, ii, t, 1, f. 6 (?).
CALIGUS BICOLOR, Lamarck, An. s. Vert., edit. 2d, v, 210.

Description. — The body is much elongated and oval.
Frontal plates large, and separated from each other by a
deep notch. Hinder edge of the carapace almost smooth.

Elytraform appendage of the second thoracic segment
scarcely extending beyond the appendages of the first
ring ; that of the third segment is narrowed towards the
extremity. The last thoracic segment is of a somewhat

^ o

oval form, and surrounded by a small pale border. The
last abdominal ring is somewhat rounded, and the lateral
caudal appendages are short and obtuse. The cephalo-
thoracic segment and the second and third thoracic elyl.ra-
forin appendages are marked in the centre with patches of
black.

Hal. — Taken from the Squahis golem, Linn., at Tor-
cross, Devonshire ; Dr. Leach. British Museum. From
the Carcharius glancus, captured a few miles from the har-
bour of Falmouth, 1849 ; W. P. Cocks, Esq.

CECROPS. 289

2. PANDARUS Boscn.

PANDARUS Boscn, Leach, Encyc. Brit. Supp., i, 406, t. -20, f, 1-10

Diet, des Sc. Nat., xiv, 535.
Desmarest, Cous. geu Crust., 339.
CALIGUS BICOLOR (var.), Lamarck, An. s. Vert., v, 210.

Description. — This species is extremely similar to the
preceding. It is smaller, and the whole body is of a pale
colour, without any of the black marks which characterise
the bicolor. Most probably only a variety.

Had.- -Taken from the Squahis initstclttx, Linn., at
Torcross, Devonshire ; Dr. Leach. British Museum.

Family 4— CECROPID^.

PANDARIENS (pars), M. ]•'.// "-ni-ih, Hist. Nat. Crust., iii, Mil.
CALIGID/E, RACE n, Leach, Diet. Sc. Nat., xiv.
BOPYRIDJE (pars), Risso, Hist. Nat. Eur. nn'rid.
CECROPIN^E, Dana, Proc. Am. Acad. Arts and Sc., IS I-'.), ."> I .

Character. — Head as in Pandaridee. One single.
lamellar, elytraform appendage on the dorsal surf;i<v ul' 1 lie
thorax. Oviferous tubes, concealed under a shield-shaped
plate, and twisted in many convolutions.

Genus 1 — CECROPS.

CECROPS, Leach, Enc. Brit. Supp., i, 1816 ; Diet. Sc. Nat., xiv, 1819.

Lamarck, Latrdllc, Uesniarest, Nor<l,,itnti>, Bttrmeis/t',; M. l\>l wards.

Character. — Elytraform appendage small, and rounded.
First three pairs of feet in the female, and all in the male,
fitted more or less for walking, and armed at the tips with
short, stout spines.

Bibliographiccd History. — Lamartiniere, who was na-
turalist in the expedition sent out under the command of
La Perouse, discovered a small parasitic animal adhering

19

290 BRITISH ENTOMOSTRACA.

to the gills of a species of Diodon, or sun-fish, taken on the
coast to the north-east of Nootka Sound. This unfortunate
fish seems to have been in a diseased state, and had three
other species of parasites adhering to different parts of its
body. The one taken from the gills he describes as a
species of Oniscus, and figures it in the atlas to ' La
Perouse's Voyage/ and also in the ' Journal de Physique'
for September 1787. His description and figure show
it to be a species of the genus Cecrops. It was Leach,
however, who first established the genus in the ' Enc.
Brit. Supp./ i, 1816, and afterwards in the 'Diet, de
Sc. Nat.' xiv, 1819. He there pointed out the difference
in the situation of the oviferous tubes ; and the genus
thus established was afterwards adopted by Lamarck,
Latreille, Desmarest, Nordmann, Burmeister, Kroyer,
Edwards,

Anatomy, Sj'c.— The body is oval, thick, and of a light
horny colour and substance. The cephalo-thoracic portion
is of a square shape ; in the male two thirds the size of
the whole body, and in the female about one third.

«/ *

The frontal margin has two projecting plates of con-
siderable size, rounded, and separated from each other by
a deep notch.

The dorsal surface is marked by a rather deep furrow
on each side, which divides this portion of the body into
three parts, the middle of a somewhat quadrilateral shape,
the lower side being the narrower, and the two lateral
parts of a triangular form. The inferior angles of these
project downwards on each side, considerably lower than
the middle portion, and have the first free segment of the
thorax lying between them. This portion is small, and
quadrilateral ; but the succeeding ring is of considerable
size, and has attached to its upper surface a lamellar plate,
like the elytraform appendages found in Dinemoura, only
it is single, and smaller than in that genus, of a rounded
form, and notched at the middle of its posterior margin.

The last segment of the thorax is very small in the

CECROPS.

male, and is covered by this lamellar plate entirely, but
in the female it is very large, nearly half the size of the
whole body. It resembles a large buckler, swollen out
laterally, and covers the whole abdomen. The pos-
terior margin is lobed at the corners, and notched in the
middle.

The abdomen is very small in the male, but in the
female it is of considerable size, two-lobed, and notched
posteriorly. The caudal appendages are very small, of
an oval form, and have three or four short hairs springing
from their inferior margin.

The antennae are very small, and consist of two shorl
articulations. The mouth-apparatus resembles closely
that of the preceding genus.

The foot -jaws are three pairs. The first pair is of
considerable size, consisting of two stout joints, and a
terminal, strong, sharp claw, deeply tinged with black.
The second pair is much smaller ; consisting also of two
joints, and two terminating claws, one much smaller tlia.ii
the other, and both of the same colour as the rest of tin1
body. The third pair is much the largest, and exactly
resembles in form and structure the first pair.

The feet are four pairs. In the male they are all small.
The first pair consists of two branches, of unequal length,
arising from a common basal joint, of moderate size.
Each branch is composed of two short joints, the last of
which gives off three terminal setae. The internal branch
is considerably the smaller of the two. The second and
third pairs have the same structure, only the basal joint
is in the form of a plate, extending across to each side,
while the fourth pair, in addition to its having this
plate larger, has the two branches composed of only one
articulation each, and this one broader and larger than in
the preceding. In the female, the first three pairs of feet
are formed as in the male, the first having a moderate-
sized basal joint, while the two others have the same
plate, of which the basal joint is composed, much broad* v
and larger. The fourth pair is very large in proportion,

292 BRITISH ENTOMOSTKACA.

and consists each of a broad, foliaceous, elongated plate,
as a basal joint, and one small single branch springing
from its side. The inferior edge of this plate is sharply
notched, and on its upper surface, covered by the last
segment of the thorax, there is a thick, waved, projecting
fold.

The oviferous tubes spring, as is usual in the animals
of this order, from the inferior surface of the last thoracic
segment of the bodv, where it articulates with the abdomen.

^j */

They are very long and slender, but instead of projecting
externally, as in the other families already described, they
are twisted upon each other in numerous loops, and lie
concealed in the hollow space between the abdomen and
the large, buckler-shaped, last segment of the thorax.
This peculiar structure was pointed out by Lamartiniere,
but he fancied these tubes to be the intestines. In the
specimen he describes, he says, " son veutre etait rempli
par un paquet d'intestins de forme ventriculaire, de la
grosseur d'un cheveu." (Loc. cit., p. 207.)

Little has been observed of the habits and manners of
the animals of this genus. Lamartiniere found them fixed
upon the gills of the Diodon, or sun-fish of the coasts of
California. In the specimens from the Irish coast and
from the English shores, they were taken from the Ortka-
goriscus mola, or short snn-fish. They have been taken
off the same fish on the French coast. Risso says, that
those in the Mediterranean " float in thousands upon the
surface of the sea, far away from the coast, and serve as
food for the wandering fishes, especially the Cepliale lune,
whose stomach is always filled with an astonishing quan-
tity of these animals." —Hist. Nat. Eur. mer., v7 141.

L.EM ARGUS. 298

1. CECROPS LATREILLII. Tab. XXXIV, figs. 1, 2.

CECROPS LATREILLII, Leach, Euc. Brit. Supp., i, t. 20, f. 1-5.
l.irmnri'J,-, An. s. Vert., edit. 1st, v, 138.
Latreille, Enc. ineth., t. 335, f. 3-9.
Desmarest, Cons, sur les Crust., 338, t. 50, f. 2.
Gnerin, Icon. Regue An. Crust., t. 35, f. 8.
M, Edwards, Hist. Nat. Crust., iii, 474.

Description. — This animal is about an inch long (the
female), and is of a pale horny colour. The frontal edge
of the carapace is deeply notched, as is also, in a less
degree, the lower margin of the elytraform appendage,
and the last thoracic segment of the body. The termi-
nating strong hooks of the foot-jaws are of a deep black
colour, contrasting strongly with the light horny colour
of the rest of the body. The male is not above one third
the size of the female.

Had. — On the Orihagoriscus nwlte, Kinsale, G. J.
Allman, Esq., August 1848. Dublin coast, R. Ball, Esq.,
W. Thompson, Esq. Selsey Bill, near Bognor, Sussex,
August 1835-6 (?), G. Newport, Esq., British Museum.
Weymouth, Professor E. Forbes, and R. M'Andrew, Esq.
In all these instances they were taken from the sun-fish,
and adhering to the gills.

Genus 2 — L.EM ARGUS.

L.EMARGUS, Ki-oyer, i, 500.

J/. Edwards, Hist. Nat. Crust, iii, 471.

C/Htrarfrr. — Elytraform appendage of considerable size.
The feet are foliaceous and branchial. The upper seg-
ments of the thorax are distinct and small.

Bibliographical History. — Kroyer established the genus
in his ' Tidsskrift,' in 1838. Finding all the feet folia-
ceous and branchial, he considered it a sufficient character
to separate the species from Cecrops, to which it is so
nearly allied, and form it into a distinct genus. M.

294 KltlTISH ENTOMOSTHACA.

Edwards afterwards adopted the genus, in his ' History
of the Crustacea.'

Anatomy, $Y?.— -The body is of an ovoid shape, and of
a light horny colour and substance. The cephalo-thorax,
which includes the head and the first ring of the thorax,
is somewhat swollen, and of a round figure in front, and
cut square at its posterior margin. It is smooth on its
dorsal surface, and does not appear divided into different
regions, as in Cecrops. The second and third segments
of the thorax are distinct, small, and narrow. The fourth
is considerably larger, and has attached to its upper edge
a large elytraform plate, which covers a great part of the
last segment. This segment is much the largest of all,
and in the female is dilated into the form of a broad and
rounded elytraform plate, which covers the abdomen
entirely. In the male it is not so large, and is simply
two-lobed.

The abdomen, in the female, is large, oval, and deeply
notched posteriorly, and rounded at the sides into two
lobes ; whilst in the male it is short and narrow. The
caudal appendages are small, and of an oval shape, with
four short, stout setae or spines, springing from their pos-
terior edge. The antennae are small, composed of three
short articulations ; the month-apparatus is of moderate
size, and the structure of these parts and the foot-jaws
is the same as in Cecrops.

The males are much smaller than the females. The
young, from the figure of Kroyer, appear to resemble a
good deal the form of the Cyclopidae. The cephalo-
thoracic portion is large, and quadrilateral in shape, and
there are five distinct segments to be seen in the body,
gradually diminishing in size as they descend, without
any appearance of the elytraform appendages. It appears
to have two large round eyes, situated in the front of the
carapace. The antennae and the feet are more largely
developed than in the adult.

PACHYCEPHALA. -95

1. L^Eivi ARGUS MURICATUS. Tab. XXXIV, figs. 3, 4.

L^MARGTJS MTJBICATTJS, Kroyer, Tidsskrift, i, 487, t. 5, f. A, B, c, D.

M. Edwards, Hist. Nat. Crust., iii, 475,
t. 39, f. 2.

Description. — The female of this little animal is about
ten lines, or nearly an inch in length, and of a light horny
colour. The carapace or cephalo-thorax is considerably
smaller than the rest of the body, and is studded all over
with numerous small prickly tubercles. The elytraform
plate and last thoracic segment arc finely serrated round
the lower margins, and are both deeply notched. The
male is about half an inch in length.

Hob. — On the Orthagoriscm moles, or short sun -fish,
W. Yarrell, Esq.

TIUBE 2— PACHYCEPHALA*

In the animals belonging to this tribe, the head is
generally much smaller than in those of tlu- preceding,
and has not the broad, flat, shield-shaped form that these
have, nor the lamellar plates on the front part, but is
generally rather thick and obtuse.

The antennae are much longer than those in the
Peltocephala, and are composed of five and six, and even
more, articulations. The thorax varies in the different
genera, in form and in the number of articulations of
which it is composed. The mouth-apparatus is generally
less strongly developed in these genera than in the others,
and the conformation of the foot-jaws is much less regular.
The feet of the animals belonging to the Pachycephala
differ also from those organs in the Peltocephala. They
are not, as in these latter, attached to a basal joint, which
extends across the under surface of the thorax in the
shape of a broad plate, but have their basal joints detached
from each other. They are all parasitic, and when young
undergo a metamorphosis like the Cyclopidae.

c, thick, and Kf^aXtj. head.

296 BRITISH ENTOMOSTRACA.

We have only one British family belonging to this
tribe.

Family ANTHOSOMAM.

DICHELESTID.E (pars), M. Edwards.
CALIGID.E, RACE i (pars), Leach, Diet. Sc. Nat.

Desmarest, Cous. gen. Crust.
ERGASILINA (pars), Kroyer, Burmeister.

Character. — Head of considerable size, in form of a
narrow, ovoid, convex buckler, and having attached to it
near the mouth a pair of large foot-jaws, armed Avith
strong hooks. Thorax furnished with elytraform appen-
dages. Feet, three pairs ; all foliaceous.

Genus ANTHOSOMA.

ANTHOSOMA, Lettc/i, Desmanst, Kroyer, M. Edwards, Durmeisler, Latretlli-.
CALIGUS, Abildgaard, Risso, Lamarck.
OTROPHESA, Risso, Hist. Nat. Eur. nicrid.

Bibliographical History.-- Abildgaard was the first
person who noticed any of the species of this genus. In
the Mem. de Copenhagen, 'Act. Soc. Nat. Havn./ 1794,
he describes a species under the name of Caliytis crassus,
with considerable details, pointing out its peculiar confor-
mation.

Leach, however, was the first to form the genus ; per-
haps without knowing Abildgaard's description or figure,
as he took as the type of his new gemis a specimen taken
from a shark on the coast of England. He first described
it in the 'Encyclopaedia Britannica,' 1816, and after-
wards in the 'Diet. Sc. Nat./ 1819.

About the same time as Leach described the individual
from which he formed the genus, Risso described shortly,
and figured very badly, the same species from the Medi-
terranean. In his 'Crustac. des Envir. de Nice/ 1816,
he describes a species of Caligus, under the name of
Califfus imbricates, which Leach ascertained from Risso's

ANTHOSOMA. 297

own specimens to be identical with his Anthosoma, though
the figure given in the work quoted above was so bad as
to make it almost impossible to identify it from that alone.
In 1826 Risso described it again in his 'Hist. Nat. Eur.
merid.,' under the name of OtropUesa imbricata, giving
Leach as his authority for the generic name !

Lamarck retains the name of Caligus, but Latreille,
Kroyer, M. Edwards, and other authors, have adopted the
genus, though only one species has as yet apparently been
described, unless the species described by Abildgaard
may be considered different.

Anatomy and Physiology, fyc. — The general form of
the animal is oval ; and we distinguish as usual the head,
thorax, and abdomen.

The head is of tolerable size, and distinct, consisting
of a stout, rather narrow, and strongly convex, horny
buckler of an ovoid shape. It is very narrow, thick, and
obtuse in front, where it has a furrow running across its
dorsal surface, and a deep notch on each side, which thus
forms a beak, and almost divides it into a separate seg-
ment. It extends backwards for some length, and becomes
considerably broader, covering a portion of the thorax.

The segments of the thorax are verv indistinct. On

O B _ i

the dorsal aspect we perceive two foliaceous elytraform
appendages of an oval shape, and of a light horny and
somewhat granulated texture. Beneath these the remain-
ing portion of the thorax is seen, of a fleshy structure,
and apparently without any divisions.

The abdomen is very small, consisting of one short
segment, which gives off two small caudal appendages,
in form of short, flat, blunt filaments of the same texture
as the elytraform appendages. Immediately beneath the
notch, on each side of the blunt beak, we see a small,
flat body, and from near the base of each of these we
find the origin of the antennae. These organs are rather
long and slender, and consist of six articulations, tapering
from the base to the extremity.

298 BRITISH ENTOMOSTRACA.

The most remarkable organs attached to the head,
however, are the first pair of foot-jaws. These arise from
between the base of the antennae, are very large and strong,
and project forwards beyond the head. They consist of
three stout joints, of considerable length, and of a cylin-
drical shape ; the second joint, near its apex, having a
tooth or spine, and the last being terminated by a curved
hook ; the hook pointed upwards and backwards. The
second pair, of three joints also, is of nearly equal
length, but much more slender, and has the terminal
joint ovate, compressed, and bifid. The third pair is
short, very thick, stout, of two joints, and terminates in a
strong claw-shaped extremity.

The mouth-apparatus resembles much that of the other
genera already described belonging to the Peltocephala ;
but the sucking-tube is not so conical or sharp-pointed.

The feet are three pairs, and are all foliaceous. The
structure of these members is very simple ; being merely
foliaceous lamellae, which lap over each other, and surround
the thorax as with a shield. They are of a light horny
texture, and somewhat granulated like the dorsal elytra-
form appendages. The oviferous tubes are straight and
very long.

From the form of the feet, and the large development
and prehensile structure of the foot-jaws, it is evident
that the animals belonging to this genus are incapable of
much motion, and are more adapted than any of the
others we have yet described, for living strictly as para-
sites. They seem, from Leach's figure of the species he
describes (in situ}, to bury their beak in the flesh of their
prey, and no doubt cause much irritation to their un-
willing host. The gill-covers to which they were found
adhering, showed the marks of inflammation of long
standing, as they were much thickened.

ERGASILJD.E. 299

1. ANTHOSOMA SMITHII. Tab. XXXIII, fig. 9.

ANTHOSOMA SMITHII, Leach, Enc. Brit. Supp., i, 406, t. 20, f. 1-6 ;

Ediub. EncyclopEed., t. 181 ; Diet. Sc. Nat.,
xiv. 533.

Desmarest, Cons. gen. Crust., 335, t. 50, f. 3.
Latreille, Cuv. Regne Auim., iv, 198 ; Enc.

metk.,t. 335, f. 11-16.
Gnerin. Icon. Cuv. Regne Anim., t. 35, f. 9.
(MffitA, An. Kingd. Crust., t. 21, f. 2.
Kroyer, Tidsskrift, ii. 295, t. 2, f. 2.
M. Edwards, Hist. Nat. Crust., iii, 483, t. 39, f. 5 ;
Cuv. Regue Auira., edit. Crocliart, Crust.,
t. 79, f. 3.

CALIGUS SMITHII, J^iuinn-k, An. s. Vert., v. 210.
CALIGUS IMBRICATUS, Risso, Hist. Nat. Crust. Nice, 162, t. 3, f. 13.
OTROPHESA iMBRiCATA,.Km0,Hist. Nat. Eur. mend., v, 136, No. 190.

Description. — Animal of an elongated oval form, about
ten lines in length ; and of a ferruginous white colour,
bordering upon yellow. When alive it has a black spot
upon the middle of the head, which disappears after
death. The dorsal elytraform appendages and the folia-
ceous feet are sprinkled over with semitransparent spots.

Hob. — Discovered sticking to a shark (the Lamna cor-
it.iiMcci) thrown ashore at Exmouth, Devonshire, by T.
Smith, Esq., of the Temple, who sent it to Dr. Leach.
British Museum.

Family ERGASILIDA

ERGASILIENS, M. Edwards, Hist. Nat. Crust., iii, 476.
NICOTHOID.E, Dana, Proc. Am. Acad. Arts and Sc., 1849.

Character. — Head of moderate size, and rounded.
Body of an ovoid or pyriform shape, the thorax being
sometimes much enlarged laterally. Feet very small, and
branched. Abdomen well developed.

300 BRITISH ENTOMOSTRACA.

Genus NICOTHOE.*

NICOTIIOE, M. Edwards and Audouin, Aim. Sc. Nat., ix, 3J-5.
M. Edwards, Hist. Nat. Crust., iii, 480.
Lati-cille, Cuv. Regne Auim., iv, 201.
Burmeister, Nov. Act. Nat. Cur., xvii, 327.
Kroyer, Tidsskrift, i.
Rathke, Nov. Act. Nat. Cur., xx, 102.

Character. — Two eyes. Antennae slender, many-
jointed. Foot-jaws very small. Thorax enlarged laterally
into the form of two large, wing-shaped lobes. Feet four
pairs, two-branched, and jointed. Body articulated.

Bibliographical History. — MM. Audouin and M.
Kd wards were the first who noticed the Nicothoe, and in
their memoir, published in 18.26 in the 'Ann. Sc. Nat.,'
they give a lengthened account of the genus. They seem
to have been struck with the peculiar appearance of these
singular creatures, and evidently had some difficulty in
ascertaining their true position. Seen from above, with
their large, wing-shaped, lateral expansions, they appeared
to them to belong to the Lerneadse. When reversed, and
exhibiting their jointed antennae and articulated feet, they
had a close resemblance to the Cyclopidte. " Except
that they have two eyes," they say, " we would not think
of separating them from these animals."

Latreille, in his " History of the Crustacea," in Cuvier's
' Regne Animal,' in 1829, places them at the end of the
Siphonostoma in his second division, the Lerneiform.es,
as coming next to the Lernese.

M. Edwards afterwards adopted the same position for
the genus, in his ' Hist. Nat. Crust ,' and this arrange-
ment has, in like manner, been followed by later authors.

Rathke is the latest writer who has noticed the Nicothoe,
and in his memoir in vol. xx of the ' Nova Acta,' he has
given us many details of the development of the young,

* Nicothoa, one of the Mnrj>K>.

NICOTHOE. 301

from the egg up towards maturity, of a highly interesting
nature.

Anatomy and Physiology, fyc. — The figure of the body
is conical, with two enormous lateral expansions, and we
can distinguish three distinct parts ; the head, thorax,
and abdomen.

The head is moderately small, rounded, and obtuse.
The eyes are two ; simple, circular, and situated on the
frontal edge. The antennae arise from under this frontal
margin, and are very slender, consisting of ten or eleven
small articulations,* each of which is furnished with a
very small seta. The mouth and the organs belonging
to it are very small. These consist of a short, truncated,
cylindrical tube, of a tolerably thick substance, and a
horny texture, and within its cavity what Rathke believes
to be two mandibles. These latter organs, however, are
so minute, that he could not state positively what they
were, nor could he figure them.

The foot-jaws are three pairs in number. The first
pair is nearly rudimentary, and appears to be fringed
with several short bristles. The second pair is somewhat
larger, conical, and consists of two joints, the terminal
joint having at its extremity two moderately strong teeth.
The third pair is considerably larger than the preceding,
and consists each of three articulations,, the first and second
of which are rather long, and moderately thick, and the
terminal one is in form of a sharp-pointed claw, which
is somewhat prolonged, and furnished on the concave
side with two teeth.

The thorax is very large compared with the size of the
head, and consists of five segments. It extends laterally,
in the form of two wing-like lobes, or wallet-shaped ap-
pendages, which diverge at first nearly at right angles,
and then curve downwards. On the upper surface we
see three narrow bands running across the central portion,

* Kroyer says ten ; M. Edwards, eleven.

302 BRITISH ENTOMOSTRACA.

which represent so many articulations, but no trace of
which is visible on the under surface. These articulations
are comparatively small, with the exception of the fourth,
which composes the enormous lateral expansion, these, in
fact, being nothing more nor less than an excessive de-
velopment of this division of the body. The last joint is
much smaller than this, but is considerably larger than
those which precede it.

The first four segments give off an equal number of
pairs of feet, and the fifth gives attachment to a rudimen-
tary pair, similar in structure to those described in the
Cyclopidse as the fulcra or supports of the ovaries. The
extraordinary enlarged lateral bags, or expansions, com-
posing the fourth ring, inclose the intestines, and as
Latreille first suggested, in all probability contain a bran-
chial apparatus, similar to that described in the large
carapace of the Apus. The chief part of its contents,
however, according to Rathke, who has paid such par-
ticular attention to this little animal, is the internal ovary.
In fact, according to this author, " these appendages are
originated by the female organs of generation, which, as
they considerably increase in volume, cause the sides of
the body to project right and left, like a sac. In each of
these lie two organs, differing in size and colour, which
may easily be recognised through the integuments, as they
shine through them very distinctly. The larger organ is
of a rose or crimson colour, and appears, under a low
microscopic power, to consist of a pulpy mass. Under a
higher power, we become aware that it is formed of an
infinite number of roundish, rose-coloured eggs, held to-
gether by a colourless, glutinous matter, which forms, no
doubt, the envelope of the organs. This rose-coloured
organ, then, is the ovary. The other, and much smaller
organ, lies under this, on the abdominal wall of the body,
is distinguished from the former by a milk-white colour,
and presents in general a winding, serpentine canal, of
uniform width, which runs along almost to the further
blunt extremity of the wing-like appendage, and from

NICOTHOE. 303

thence proceeds in a curve round that part where the
appendage proceeds from the body, into the middle por-
tion of the same, and where it evidently has its issue on
the same side where the sexual aperture occurs. The latter
organ, which is wont to contain a somewhat thickish fluid, is
not, apparently, an exudation of the ovary, but something
similar to those organs in the Lerneadse and Cyclopidse,
which, in the formation of these clusters of eggs, give
forth a glairish fluid, soluble in water, which I have more
minutely described in a treatise on Dechelesthium stiirionis,
and Lern&opoda stettaia, and have called it the cementing

organ."

The intestine is a simple canal, which does not show
any appearance of an enlargement indicating a stomach.
In the fifth segment we find the two openings of the
sexual apparatus.

The feet are very small, and the first four pairs are all
alike, consisting of a basal joint of comparatively large
size, and two branches, each composed of three short
articulations, furnished with tolerably long setse. The
fifth, or rudimentary pair of feet, is extremely small. It
is formed of two somewhat compressed joints, of nearly
equal length, the terminal one being provided with five
pretty long bristles.

The abdomen is slender, and is divided into five joints,
which become gradually smaller as they succeed each
other. The last is slightly lobed at the extremity, and
sends off two long, thick, simple setae or bristles, and
several very much thinner and shorter ones.

The external ovaries are very large, of an oval shape,
of a rosy colour, and contain a very great number of ova.
They take their origin from the fifth ring of the thorax,
where the opening of the sexual organs has been already
described to exist.

The Nicothoe is found attached, often in considerable
numbers, to the gills of the common lobster. The animals

* Nov. Act. Ces. Acad. Nat. Cur., xx, 102, 1813.

304 BRITISH ENTOMOSTRACA.

plunge themselves deeply amongst the filaments of which
these organs are composed, and remain so firmly fixed to
the spot where they attach themselves, that iro efforts can
make them move. " They allowed themselves," says
M. Edwards, " to be torn to pieces, without making the
least movement, or quitting their hold. Plunged into
fresh-distilled water they were soon killed, but did not
fall off, and when the piece of gill putrefied, they putrefied
along with it, without their ever making any motion.
When plunged into spirits of wine, they made no move-
ment of contraction visible, even when examined by means
of the microscope. Taken carefully off, with all possible
precautions not to injure the animals, and placed in a
glass of sea-water, though watched for several hours, and
though they lived during that period, as might be seen
from the peristaltic movement of the intestine, they made
no attempts themselves at locomotion."

The males have never yet been observed, but in all
probability, as the animals of this genus approach so
much in their habits to those of the Lerneadse, they are,
as in them, very small, unattached, and capable of moving
freely about in the gill-cavity, or attaching themselves to
the females.

All the specimens yet observed have had the wing-
shaped appendages, and invariably, when of a large size,
have had the external ovaries suspended from the body,
and full of eggs. These are spherical in shape, and of a
very pretty rose colour. After the egg has made some
progress, it assumes the appearance of a somewhat irre-
gular oval, a little flattened on its sides, on each of which
a pair of limb-like knobs or excrescences are visible,
situated at a little distance from each other. The front
pair most probably become antennae, and the posterior,
foot-jaws.

A very curious circumstance has been observed by
Rathke, with regard to the further development of these

* Ann. So. Nat., ix.

N1COTHOE. 305

ova into the larva state. In such creatures it is extremely
difficult to trace their full development up to maturity ;
but Rathke has observed that the young of the Nicothoe
are considerably advanced in development before they
leave the ovary, and that while there, some of these em-
bryos attain a considerably larger size than others, and
pursue a somewhat different progress. The one, the
larger kind, Rathke considers may be the female, and the
smaller the male, though he confesses that the smaller
form is the most abundant in the ovaries. The larger
embryo has a flat appearance, and consists of a very large
and broad upper portion or cephalo-thorax, and a narrow
posterior portion, nearly of the same length as the upper.
The upper part, or cephalo-thorax, is rounded and nar-
rower in front, much expanded laterally, and contracts
again posteriorly. On the upper part of the dorsal sur-
face, situated near the edges, we see two light, reddish-
brown points, one on each side, which are no doubt the
eyes ; while it is equally clear, the large lateral expansions
become the wing-shaped appendages in the adult.

On the ventral surface we see, at the upper part, two
antennae of considerable size, consisting of three stout
articulations ; and a little below these organs we see a pair
of short members, of one joint, forming pretty strong
hooks or curved claws, which are no doubt the first pair
of foot-jaws. Between these organs we find, exactly in
the centre, a small protuberance, representing the organs
of the mouth ; and at some distance below this we see two
other pairs of members, the first of which consists of two
joints, the basal, stout and of considerable size, the ter-
minal much smaller, and ending in a strong hook-shaped
claw. The second pair is much larger, and is formed of
three articulations, the middle one the longest, and the
terminal armed at the extremity with a stout claw. These
two pairs of organs are the second and third pairs of foot-
jaws in the adult. A little lower still, close to the posterior
margin of the cephalo-thorax, we see another pair of mem-
bers, flat and of considerable length. They consist of

20

306 BRITISH ENTOMOSTRACA.

three joints, the terminal one being provided at its ex-
tremity with several short setae.

The inferior half of the body of the animal is composed
of four segments, the first of which is the largest, and has
on its ventral surface a pair of members exactly similar to
the last pair described, belonging to the cephalo-thorax.
The other segments decrease in size as they descend, and
the last is slightly lobed at the extremity, and furnished
with several setae.

The smaller of the two forms of embryo differs in the
shape as well as the size of the cephalo- thoracic por-
tion, being ovate, the superior portion broader than the
inferior, and not expanded laterally. The lower half of
the body is narrower than the corresponding portion of
the first form, but consists of the same number of seg-
ments.

The eyes and antennas are similar, but the latter organs
are proportionally larger.

The foot-jaws are either wanting or so rudimentary 'as
not to have been observed, while the last two pairs of
members are narrower and shorter than those in the first
form.

In general conformation we thus find the young of the
Nicothoe very similar to the young of the Cyclops, and
we can trace the gradual transformation of the different
parts of which the animal is composed. The eyes, mouth,
antenna?, and three pairs of foot-jaws already exist, though
in their progress towards maturity they undergo consider-
able changes. We find, however, only two pairs of
swimming-feet, while in the adult there are five. The
two upper pairs become smaller, but assume a branched
form, and the three others are added during the animal's
progress towards maturity. The whole body consists, in
the young, of five segments, in the adult of ten ; five rings
are thus added during its growth, before it reaches the
full-grown state.

In general form, the Ergasilidae appear to connect the
Cyclopidae with the Lerneadae ; but in habits and mode

LERNEAD^E. 307

of life they approach more closely to this latter order than
any other family of the Siphonostoma.

1. NICOTHOE ASTACI. Tab. XXXIII, fig. 11.

NICOTHOE ASTACI, Audouin and M. Edwards, Ann. Sc. Nat., 1st series,

ix, t. 49, f. 1-9.

Latreille, Cuv. Regne Aniin., iv, 202.
Burmeister, Nov. Act. Nat. Cur., xvii, 327.
Guerin, Icon. Regne An. Crust., t. 35, f. 12.
Kroyer, Tidsskrift, ii, t. 3, f. 7.
M. Edwards, Hist. Nat, Crust., iii, 481, t. 40, f. 23.
Rathke, Nov. Act. Nat. Cur., xx, 102, t. 5, f. 1-10.

Character. — The length of this species is about two
lines, and the colour is of a rosy hue. It is as yet the
only known species of the genus.

Hab. — On the gills of the common lobster. London
market, March and April, 1849 ; W. B. Falmouth, Sept.
1849 ; W. P. Cocks, Esq. British Museum.

ORDER II— LERNEADJE.

Mouth suctorial. Thorax not articulated. Feet and
other organs belonging to thoracic segment nearly rudi-
mentary. No eyes. Body very outre in appearance.

Bibliographical History and Systematic Arrangement.—

The existence of the Lerneae seems to have been known
to the ancients. Aristotle informs us, in his ' Historia
Animalium,' that the tunny and sword-fish are tormented
by a sort of worm, which fastens itself under the fin, and
causes such irritation to the animal, that it often leaps out
of the water, and falls on board of ships.* Pliny repeats

* "Thunni et gladii agitantur asilo cauis exortu, habent euira utrique
per id tempus sub pinna ceu vermiculum, quein asilum vocant, effigie scor-
pionis, magnitudine aranei ; infestat hoc tanto dolore, ut uon minus interdum
gladius quam delphinus exiliat, nude fit, ut vel in navigia saepenumero in-
cidat." — Lib. viii, cap. 19.

308 BRITISH ENTOMOSTRACA.

the assertion almost in the words of Aristotle.* Oppianus,
in his poem ' Alieuticon,' describes the sufFerings of the
poor tunny and sword-fish in moving language, and
asserts that the fish are frequently killed by their pigmy
assailants. t Athenaeus repeats what his predecessors have
written before him ; and Salvianus, in his ' Aquatilium
Animalium Historia,' 1554, quotes at length the passages
bearing upon the subject from Aristotle, Pliny, Oppianus,
and Athenaeus.j Rondeletius, in his 'Libri de Piscibus
marinis/ 1554, repeats, for the sixth time, Aristotle's and
Pliny's accounts of this parasite of the tunny and sword-
fish, and to prove his personal knowledge of the little
animal in question, gives a figure of a tunny, with the
parasite attached, near the pectoral fin.§ He says it ad-
heres so tenaciously, that it cannot be shook oft' by any
agitation of the body of its host.

Conrad Gesner, in his 'Historia Animalium — De Aqua-
tilibus,' 1558, enters largely into the history of this para-
site. He describes its structure and appearance, " be-
cause," he says, " few people know what this parasite is, as
it is very small, seldom to be seen, except at the time of
the rising of the dog-star, and then not on many fishes,
but only on the tunny, sword-fish, and occasionally the

* "Animal est parvum. scorpiouis effigie, aranei magnitudine. Hoc se,
et thyuno, et ei qui glaclius vocatur, crebro delphini magnitudine excedenti,
sub pinna affigit aculeo, tantique infestat dolore, ut in naves seepeuumero
exiliant. Quod et alias faciunt aliorum vim timeutes, mugiles maxime, tarn
pnEcipuae velocitatis, ut trausversa navigia interim superjactent." — Hist.
Nat., lib. ix, cap. 16.

f " Dum canis ardenti turbatur sydere cailum

Et tlivnni et gladii diro vexantur asilo :
Qui n'xus madidis illos contundit in alis,
Non arcere queunt, non lianc propellerc pestcm,
lucutit hoc celeres vires, stimulosque feroces
Concitat ; armantur rabie, furuentque dolore :
Invitosque agitat pestis t'uribunda uatautes :
Exhorret vuinus, bacchautnr in aequore lata.
Hi torti stimulis incursant navibus altis :
Et ssepe in terram saliunt e gurgite vasto,
In tanto volvuut luctantu membra dolore,
Et vitam in tanto mutant cum morte furore."

Alieuticon, traduct. Laurent. Lippio, liber xi, p. 24.
J Pp. 126-8. § P. 249.

LEKNEAD^E. 309

dolphin (and not even on every individual)." He gives
a figure of it slightly magnified,* and repeats the repre-
sentation of it in situ on the tunny, f as previously given
by Rondeletius. " It adheres so firmly," he remarks,
" that it cannot be removed without tearing it. It sucks

O

the blood of the fish, like as the leech does, till it falls off
through very fulness, and then dies." On this account
these fishes (the tunny especially is mentioned) are poor
and bad during the height of summer, though, owing to
their being so sadly tormented by these plagues, they are
more easily caught at that time than they are in winter,
at which time they are in better condition.! Tne speci-
men he describes as having examined himself was, he says,
of a white colour, and was found adhering " ad pisceni
Pagrum."

Pernetty, in his ' Histoire d'un Voyage aux lies
Malouines, fait en 1763-4,' published at Paris in 1770,
found apparently the same species adhering to a tunny,
and gives a figure of it, which seems to represent pretty
nearly the animal delineated by Gesner.

More recently, M. de Blainville, in the 'Journal de
Physique,' xcv, 1822, has figured, from a MS drawing of
M. Marion de Proce, a similar species, which he has called
Lerneomyzon incisa, and which I have no doubt is the
ottrrpoc, or Asilus marinm of Aristotle, Pliny, Rondeletius,
and Gesner, and nearly identical with the animal figured
by Pernetty.

Boccone, a Sicilian gentleman, in his c Recherches et
Observations naturelles,' published at Amsterdam in 1674,
informs us, that at Messina his attention was called by
M. Scilla, a famous painter and antiquary of that town, to
the fact that the Xiphias, or sword-fish, was well known
to the fishermen on the coast to be tormented by a parasite
which they called Sanguisuca. The only information he re-
ceived was that the motion of the creature was like that of a

* P. 112, figure annexed,
f P. 1152, figure annexed.
% Pp. 112,113.

310 BRITISH ENTOMOSTRACA.

gimlet in plunging itself into the flesh of the fish. He
succeeded, however, in obtaining a specimen, which he
describes and figures.* They bury, he says, their whole
head or trunk in the flesh of the sword-fish. They are
not generally confined to one part of the body, but always
on such places as that the fin of the animal cannot reach
them. Boccone refers this species to the Oistros, or Asilus
marimis of Gesner, &c., and says that no figure is given
of it by Gesner, or any of the authors who take notice of
it. In this, however, as I have shown above, he was
mistaken ; and had he observed the figures given by
Gesner and Rondeletius, he would not have made the
mistake of asserting the two species to be identical. t Its
being found upon the Xiphias, or sword-fish, no doubt
was the cause of the mistake. He makes, however, a very
curious observation in connexion with this parasite. " This
sangsue," he says, " appears to be tormented by a louse
which I have never seen on any other animal. It is of the
size of a pea, and attaches itself firmly to the animal,"
p. 292.

Gesner, in quoting Aristotle's description of the Asilus,
had already observed, " adeo uihil est quod hoste careat"
(p. 112), a remark well illustrated by the little fact just
mentioned by Boccone. ;£

Muraltus, in the ' Miscellanea curiosa siveEphemeridum
Medico Physicarum Germanicarum Academise Naturae
Curiosorum,' published at Nuremberg in 1682, mentions
that while dissecting a specimen of the Mustelafuviatilis,
he found an insect inserted into the eye of the fish, and
hanging out from it. It was so firmly fixed in the eye by
the arms, that no doubt, he says, these animals caused the
humours of the eye to escape, and thus rendered the fish

f Recherches et Observations, p. 284, et sequent, tab., p. 287.
f This animal is a species of Penella, or Peuuatula, Linn.

Some fleas there are that live on men,

And these have fleas on them again ;

Large fleas have lesser ones that bite 'em,

Thus fleas eat fleas n<l /'«/////////// .'

LERNEA D;E. 311

blind.* Baker, in the ' Philosophical Transactions' for
1744, vol. xliii, describes a somewhat similar " new dis-
covered sea-insect," which he calls " the eye-sucker," and
which he found " fixed by the snout'' to the eyes of sprats.
The figure is very poorly executed, so much so, that it is
not possible exactly to make out the species ; but a Lernea
does infest the common sprat of this country, and has been
figured by Mr. J. Sowerby in the ' British Miscellany.' f

In 1746 Linnaeus, in his ' Fauna Suecica,' first edition,
described a parasitic animal found upon the Cyprinus
Carassius, " whose blood it sucks." He established from
this species the genus Lernea. In his ' Iter Wast Gotha,'
1747, he notices another species found on the gills of a
species of Gadus ; and in his second edition of the ' Fauna
Suec.,' 1761, he adds a third, as inhabiting the gills of
the salmon, which had been figured and described by
Gisler, in the 'Act. Holmens.' (Kongl.Vetensk. Handling.)
for 1751, under the name of Pedicidus salmonis.\ In
the 'Syst. Nat.,' 12th edition, 1766, he adds a fourth
species to the list, and up to that time these four consti-
tuted all that Linnaeus admitted into the genus Lernea —
a genus which, since his time, notwithstanding the diffi-
culties attending its investigation, has increased a hundred-
fold, and now constitutes a large family. So bizarre in
appearance are these Lernese, that Linnaeus had no idea
that they belonged to the Crustacea ; on the contrary, he
places them amongst the worms.

" Of all the curious creatures which the naturalist meets
with in his researches," says Dr. Johnston, " there are
none more paradoxical than the Lerneae ; none which are
more at variance with our notions of animal conformation,
and which exhibit less of that decent proportion between
a body and its members which constitutes what we choose
to call symmetry or beauty."^ It is no wonder, then,

* Decuria, ii, p. 126.

•(• The Lerneonema monillaris, M. Edwards.

;!; Act. Holmens., 1751, p. 181, t. 6, f. 1-5.

§ London's Magazine of Natural History, viii, olio.

312 BRITISH ENTOMOSTRACA.

that with the scanty knowledge he had of their habits and
history, Linnaeus should have considered their proper
place in the system of nature to be amongst his Mollusca ;
animals belonging to his class Vermes, and characterised
by him, from the softness of their body and the want of a
shell. The various editors and continuators of Linnasus,
and most systematic writers, up to a late date, have more
or less strictly followed his arrangement. Both Bruguiere,
in the ' Encyc. method.,' 1792, and Blumenbach, in his
' Handbuch,' 1779, have adopted his place for them in
their systematic arrangement. Cuvier, in his ' Tableau
elementaire,' 1798, arranges them amongst the Mollusca
gasteropoda, placing them along with those which have
free motion in the water. Lamarck, in his ' Systeme des
Anim. sans Verteb./ 1801, likewise fixes them amongst
the Mollusca, arranging them with the naked Mollusques
cepliaUs. Bosc also admits them among the Mollusca ;
but observes that they approach the intestinal worms.
Lamarck, dissatisfied with his first arrangement, after-
wards, in his ' Philosophic Zoologique/ 1809, removes
them to the Annelides, placing them along with the
Planariac and Leeches. Still later, in his ' Extrait du
Cours de Zoologie,' 1812, he indicates the necessity of
forming a distinct class to receive them, which he calls
Epizoaires, a series of animals which he could not refer
exactly to any of the already determined classes of the
animal kingdom ; and in the ' Hist. Nat. Anim. sans
Verteb.,' first edition, 1816, in placing them amongst
the Epizoaria, he says, " these animals approach near to
worms and to insects, without belonging to either. They
indicate the existence of a particular series, which may
probably form a new class, and which may properly fill up
the great void which exists between insects and worms."
Of this little group he adds, " I only at present make a
simple provisional indication."

Oken, in 1815, in his 'Lehrbuch der Naturgeschichte,'
following Linnaeus in placing the Lernese amongst the
Mollusca, was the first who commenced dividing them

313

into different generic groups. De Blainville informs us,
that a year or two before that, in 1814, during a journey
to England, he had been led to see the necessity of sepa-
rating them into different genera also ; but that he was
induced to assign them a place amongst the Entomozoa,
or articulated animals, viewing them, he says, " as an ano-
malous group of worms." He acknowledged, as Oken
had done, the relations which evidently existed between
them and the Caligidse, but still did not incline to refer
them to the Crustacea. This view of these curious animals
he published in 1816, in his ' Prodromus de Classification
nouv. du Regne Anim.,' without at the time being aware
what Oken had previously done.

In 1817 Cuvier adopted the view taken by Bosc, and
in his ' Regne Animal' placed the Lernese amongst the
intestinal worms. There is nothing very instructive in
this detail of the difficulties felt by systematic writers in
knowing or determining where these curious, and at first
sight bharre-\oo\i\\\g animals should be placed. Little
was known of their habits, manners, or mode of propa-
gation, and though as we have seen, their near relations
with the Caligi had been observed by several authors,
they had not sought to resolve the question by deeper
anatomical researches, or investigations into their mode
of life and habits. Their true position, however, was soon
about to be ascertained. Soon after Cuvier had published
the first edition of his celebrated work, the ' Regne
Animal,' a French physician at Havre, M. Surriray, made
the important discovery that the ova were contained in
the long filaments suspended from the abdomen, and that
the young, when born, bore no resemblance to their
parent, but on the contrary were extremely similar to the
young of the Cyclops. De Blainville recorded the fact
in the 'Journal de Physique,' 1822, in his excellent
article, " Lernea," and fully admitted the truth of
Surriray's statement. In this article he remarks the near
approach of his last genus among the Lerneadse to the
last of the Caligidse, and traced the almost insensible gra-

314 BRITISH ENTOMOSTRACA.

dations by which we are carried from that genus to the
Caligus itself, thence to Argulus, and through it to the
Apus and other Branchiopods. He still retained them,
however, amongst the Epizoa; and Desmarest, in his ' Cons,
gen. sur la Classe des Crust.,' 1825, appears to have
been the first to distinctly refer them, as a group, to the
class Crustacea.*

In 1826, MM. Audouin and Milne Edwards discovered
a parasite upon the Astacus, or lobster, the Nicothoe5f
and in the course of their observations upon the history
of this curious Siphonostome they came to the conclusion,
reasoning from analogy, that the Lerneae were real
Crustacea, that " became monstrous after they had fixed
themselves" upon the animal which was to serve them
with nourishment.

Kroyer informs us that several German zoologists, as
Nitsch, Leuckart, and Schwegger, had advanced similar
opinions, though, it would appear from his references
to their observations, upon very insufficient grounds.
Zoologists, however, were gradually coming to the con-
clusion that these fantastically-formed creatures were in
reality cmstaceous. But it is to Alexander von Nordmann,
an eminent Prussian naturalist, that we are indebted for
a complete and satisfactory solution of our doubts upon
the subject. In his work, ' Mikrographische Beitrage
zurNaturgeschichte derWirbellosen Thiere,' Berlin 1832,
he has confirmed the observations of Surriray upon the
young when first hatched from the ova, shown the dis-
similarity which exists between the male and female, and
thrown much light upon the anatomy of this interesting
group of animals, especially with regard to the structure
of their mouth and feet. Since the publication of his
excellent work, his observations have received still further
confirmation, additions and corrections, by three zoologists
of considerable reputation, the well-known entomologist

'* Cons. gen. sur la Classe ties Crust: ;X.TS. p. 31o, note.
f See above, p. 300.

LERNEAU^:. 315

Burmeister ; * an Austrian naturalist, Vincenz Kollar;f
and the acute observer Rathke. j

Cuvier, in a note in the second edition of his ' Regne
Animal,' 1830, p. 256, seems to have been somewhat
staggered in his opinion as to the proper place in the
system in which the Lernese should be placed. The
difficulty with him, as to referring them to the Crustacea,
seems, from this note, to have depended upon the males
not having as yet been observed. Speaking of MM.
Audouin and Milne Edwards's opinion as to their being
crustaceous, he says, "pour conserver cette opinion, il
faudrait pouvoir retrouver ces males." Had Nordmann's
discovery of the existence of the males been known to
Cuvier, in all probability the Lernese would not have re-
mained, as they now do, amongst his intestinal worms.

In 1837 Kroyer published, in his ' Tidsskrift,' vol. i,
a very excellent paper upon the Natural History of
Parasitical Crustacea., to which I am much indebted
for many particulars with regard to their economy and
habits. And since then, M. Rathke, in vol. xx of the
' Nov. Act. Acad. Caes.' 1843, has still further illustrated
many points of the anatomy, habits, and manners, of
some of the animals belonging to this group.

In this short bibliographical sketch I have not enume-
rated many original observers of Lernese after the time of
Linnaeus; however, then' number is considerable. Strom,
in the 'Physiske og Oeconomisk,' 1762; Ellis, in the
'Philosoph. Trans.,' liii; Fabricius, in the 'Fauna Grcen-
landica,' 1780; Mliller, in the ' Zoologia Danica,' 1781;
Hermann, in the ' Naturforscher,' xix, 1783 ; Schrank,
in his 'Voyage en Boheme,' 1786; Lamartiniere, in
the 'Journal de Physique,' 1787, and in the Atlas of
the ' Voyage of La Perouse ; ' Holten, in the ' Acta
Danica,' v, 1799; De la Roche, in the ' Bulletin de la Soc.
Philomath.,' 1811 ; Chamisso and Eysenhardt, in the

* Nov. Act. Acad. Csesar. Nat. Cur., xvii, th. i.
f Annal. der Wiener Museums, i, abth. i.
% Nov. Act. Nat. Cur., xx.

316 BRITISH ENTOMOSTRACA.

' Nov. Act. Acad. Nat. Cur./ 1821 ; Mayor, in the
'Nouv.Bull.de la Soc. Philomath.,' 1824; Lesueur, in
the 'Journal of the Acad. of Nat. Sc. of Philadelphia,'
1824; Scoresby, in his 'Arctic Regions, 1820;' Grant,
in Brewster's 'Edin. Journal of Science,' 1827 ; Retzius,
in the 'Kongl.Vitensk. Acad. Handling., 1829; Johnston,
in London's 'Mag. of Nat. Hist.,' 1836, and various
other naturalists, have all added more or less to our in-
formation, and extended our knowledge of the species of
these animals ; while M. Edwards, in his ' Hist. Nat.
Crust.,' has collected all the species together, and arranged
them in their respective families and genera.

Anatomy and Physiology, &fc. — The form of the animals
belonging to the Lerneadse is very variable. " Respecting
this," says Kroyer,* " it is not easy to say anything
general. The remark only forces itself upon every ob-
server, that the exterior of these animals is often so highly
fantastical, that we are disposed to admire the freaks of
nature in bringing forth such forms. But it is evident,
that when continued observations and investigations have
put us in possession of the condition of these forms, we
shall see here, as everywhere else, that singularity resolves
itself into regularity."

Eor the most part the skin, or external envelope, is soft
and flexible, but there are many species in which it is
somewhat of a cartilaginous consistence. Nordmann has
discovered that it consists of a threefold structure ; an
external layer, tolerably firm and elastic ; next, a very
loose and soft cellular tissue ; and finally, a third layer,
composed of a number of muscular fibres crossing each
other in length and breadth, and having, in consequence,
a reticulated appearance.

We can generally trace, more or less distinctly, a
division of the body into two parts ; the first of which,
the smaller of the two, forms the head, and the other the

* Tidsskrift, p. 171.

LERNEAD.E. 317

thorax. This latter is generally of considerable size, whilst
the abdomen, in almost all the species, has become very
nearly rudimentary. Attached to the head, in the greater
number of the Lerneadae, we find one pair of antennae,
and two pairs of foot-jaws, by means of which they attach
themselves to their prey. In a few we find no antennae,
and only one pair of foot-jaws. We find no appearance
of eyes. The organs corresponding to the thoracic feet
of the Siphonostoina are variable in form, but in general
are almost rudimentary, sometimes, indeed, altogether
wanting. It is this very rudimentary state of the organs
of motion and other appendages that forms the principal
mark of distinction between the Lerneadae and the Sipho-
nostorna. The mouth, according to Kroyer, has generally
the shape of a blunt, spherical snout, placed on the most
advanced portion of the head, and terminating in a
roundish opening, though in some of the genera it is in
the form of a slight elevation merely, and is placed at
a considerable distance from the anterior part of the
head.

The manner in which these animals fasten themselves
to the fishes upon which they live varies much. In some,
it is by means of the foot-jaws alone, which in these
species are strong, and of a hooked form. In others, it
is by means of two long appendages springing from the
upper part of the thorax, one on each side, and uniting
at the tip, forming at their junction a sort of round
button. In a third set, again, the organs of attachment
are a series of horns or appendages proceeding from the
side of the head.

The females are generally furnished with large external
ovaries, containing numerous ova. The intestinal canal
is very distinct, extending through the whole body. It
is cylindrical, and widens towards the middle of its length
into a stomach. The motion in the living individuals
may be plainly seen, a series of rhythmical movements to
both sides, occurring to the number of from about sixty
to sixty -five in the minute ; besides a sort of peristaltic

318 BRITISH ENTOMOSTRACA.

motion, or an alternate contracting and lengthening itself
upwards and downwards.

Nordmann has described what he considers may be
the liver and brain, and has pointed ont the heart. This
latter organ contracts and expands regularly, but no blood-
vessels are to be seen, the blood flowing freely about in
the hollow of the body and arms. The blood is a clear,
watery-like fluid, composed of three kinds of globules,
differing in form and dimensions. The internal ovaries
lie on each side of the intestinal canal, and open by means
of a canalis deferens on each side of the inferior por-
tion of the thorax, where the external ovaries take their

origin.

In general, it is only the adult female of the Lerneadae
that we are in the habit of observing, and in an animal
whose organs of motion and perception for the most part
are merely rudimentary, and whose existence is strictly
stationary, the manner of life must be very simple. Im-
moveably fixed upon the fish which serves it for food, its
existence depending upon the life of its host, it requires
neither feet to transport it from place to place, nor eyes
to guide it in its search for fresh abodes. In fact, the
whole of its active existence consists in the two operations
of taking food, and propagating its species. We find
them in all instances more or less deeply fixed in the
tissue of the parts upon which they have taken up their
habitation, and often so deeply lodged, that little else but
the oviferous tubes are visible externally. There they
remain, living at the expense of their host, those that
inhabit the branchia3 or are deeply fixed in the soft tissue
of the bodies, drinking up the blood ; and the others
which are fixed less deeply, and take up their abode
under the fins and such places, sucking the slimy juices
of the skin. As they are never seen to change their place
of residence, the question naturally occurs — how7 did
they come there originally ? Having no feet to propel
them through the water, and no eyes to guide them, even
if they possessed the faculty of transporting themselves

LERNEAD^E. 319

from one place to another, how is it that we thus find
them fixed upon these fishes, mature and possessing ova?
Blainville answers this question, by saying, " it is difficult
to conceive how these animals, which spring from eggs,
are fixed upon fishes without admitting that in their young
age they possess a little motion." M. Surriray had at
that time demonstrated to Blainville the existence of the
young when just hatched ; but less importance was at-
tached to this discovery than it deserved ; and it was not
till Nordmann corroborated the fact, and followed it up
by his more patient researches, that we were enabled to
answer the question fully.

The circumstance that the Lerneadae soon die after being
taken from the fish that has served them for nourishment
and a habitation, certainly throws great difficulty in our
way of observing the development of the young ; but we
now know that when hatched, and for some time after-
wards, the young Lerneadse are nimble and active, and
possess both the organs of motion and the faculty of
using them. When they first come out of the egg they
are of an oval shape, and very much resemble the young
of the Cyclopidse. They possess a large eye, situated in
the centre of the anterior and upper part of the body, and
are provided with two large pairs of swimming-feet, and
a pair of jointed antennae. As in the Cyclopidae, these
young Lerneadse cast their skin repeatedly before they
arrive at maturity. After the first moulting, the body is
seen plainly divided into two parts, the anterior of which
is furnished with three pairs of hooked feet, and the pos-
terior with two pairs of swimming-feet. No doubt there
are a good many stages of development to go through
before they assume the mature form, but it has not yet
been possible to follow them out. It is not the least
curious part of the history of these singular-looking ani-
mals, that the young should thus stand on a higher stage
of development than the mother ! and that their progress
from youth to maturity should be in the directly opposite
ratio to that of all the other Crustacea. At what period

320 BRITISH ENTOMOSTRACA.

of their existence they fasten themselves upon their prey
is at present unknown ; but no sooner apparently does
this happen than the eye disappears, and the feet either
disappear also, or are transformed into other organs. In
some they are changed into foot-jaws, by means of which
they fix themselves upon the body of the fish they select
for their habitation. In others they are transformed into
long and strong prolongations like arms, which unite
together either at the tips only, or from the roots all the
way up to the point, where they send forth a short horny
stem, that widens into the shape of a round button, and
which, when buried in the skin or flesh of the fish, forms
such a strong attachment, that the Lerneadse cannot be
detached without being torn, or by being carefully dis-
sected out. Most probably the species in which this
development takes place first fasten themselves to their
foster-mother by the foot-jaw- s, as the first-mentioned set
do, and after being buried in the flesh, these organs
assume this peculiar formation, otherwise it is difficult to
conceive how such an instrument could penetrate deeply
into the body of the fish. A third mode of transforma-
tion of the feet appears to be into a series of horny
branchlets developed round the mouth, and which, when
they have penetrated deeply into the soft parts of their
host, serve effectually to retain the parasite in its place.
The adult Lerneadae show, with the exception of taking-
food and laying eggs, very few and feeble signs of life,
whether attached to the nourishing animal or wrhen sepa-
rated from it. Many of the genera show no external
signs of life at all after separation from their foster-mother;
others move their jaws for a short period, or their head
may be seen to move leisurely in different directions for a
little time and then cease. In one species (L. brauchialis),
Kroyer tells us, that he observed a singular phenomenon
that nobody else had before noticed. When he touched
an individual, it squirted, he says, " from the vent, a
transparent stream of fluid to the distance of a foot and
a half, and this it repeated several times one after
another.'

LERNEAD^E. 321

That part of the history of the Lerneadae which is
connected with their sexual relations and propagation is
still involved in much obscurity. But the details we have
received from Nordmann and Kroyer, with regard to the
males, are no less singular than many of the other curious
parts of the history of these animals. By some of the
earlier observers it was supposed that those individuals
which had not oviferous tubes were males, while others
imagined that they were hermaphrodites. Neither of
these opinions, however, will stand the test of inquiry.
The ovaries of the female, after the eggs have attained
maturity, burst and disappear, and thus, as Kroyer ob-
serves, " the Lernea which to-day was considered a female,
to-morrow might be regarded as a male." In the course
of investigating different species of Lerneadas, Nordmann
discovered, in several instances, small bodies adhering to
the generative organs of the females, which, on closer in-
spection, proved to be animals that differed very much in
appearance from the female, and, on the contrary, bore
considerable resemblance to the young ones in the first
stage of their development. These he believed were the
males, and though Burmeister has thrown great doubts
as to the entire accuracv of Nordmann 's observations,

f */

his statements as to the fact of these animals being males
are borne out by Kroyer and others. It is probable, as
Nordmann remarks, "that the males and females are
mixed together when they come out of the eggs, but that
they develope themselves differently at the last change of
skin." They continue to show uniformity in regard to
the form of the head, and the form and situation of the
parts connected with it, but they want the apparatus for
attaching themselves which the females possess, having
instead, two pairs of strong, hooked feet. They differ
constantly in the form of the other parts of the body, and
show a remarkable diversity from the female with respect
to size, being very much smaller. These males bear a
strong resemblance to each other, even in different genera,
in which the females are very unlike. This fact and the

21

322 BRITISH ENTOMOSTRACA.

preceding, viz. the great difference of size, have been
considered by Burmeister as strong objections to the truth
of Nordmann's conclusions. It is true many experiments
and careful anatomical investigations are still wanting to
establish conclusively the facts as stated by Nordmann,
but still the observations made by him upon one or two
genera leave little room to doubt the truth of the opinion
as regards these individuals at least. Kroyer considers
that the Lerneadse are at a very early age capable of
breeding, though it is not yet known at what stage of
development exactly they become so. Certain it is we
see, in small specimens of some of these animals, small
ovaries and a few eggs contained in them, whilst as the
females increase in size the ovaries become larger, and the
eggs more numerous. Burmeister affirms that the Ler-
neadse only propagate once, and the ovary continues to
increase in size, and the eggs to increase in number, till
they become mature, and that then the parent Lernea
has played her part. Kroyer doubts this ; and the op-
posite opinion holds better with the analogy of the other
Entomostracous Crustacea. But upon this point direct
experiments are wanting.

The animals belonging to the Lerneadas have been
divided by M. Edwards into three families, according to the
manner in which they become fixed to their prey. Some,
as I have already mentioned, are attached by means of
the head itself, which is furnished with one or more pairs
of horn -shaped appendages projecting laterally; others by
means of long arm-shaped appendages springing from the
thorax, united to each other at the tip, and terminating in
a horny button in the centre ; a third set again are fixed
by the aid of stout foot-jaws, armed with strong hooks.
These characters afford good marks of distinction, and I
propose naming them accordingly :

The first set are the Anchoraceracea ;

The second are the Anchoracarpacea ;

And the third are the Anchorastornacea.

(JHONDRACANTHID.*;. 323

TKIBE \-ANCHORASTOMACEA*
CHONDRACANTHIENS, If. Edwards, Hist. Nat. Crust., iii, 491.

Character — Females. Attached to their prey by means
of their foot-jaws, which are stout and armed with strong
hooks. One pair of antennas ; generally very distinct.
Thoracic feet nearly rudimentary, or represented by appen-
dages of considerable size, but differing in form from
ordinary feet.

Males. Free and unattached ; very small and differing
totally in appearance from the females.

Family CHONDRACANTHID^.
CHONDRACANTHIENS (pars), M. Edwards.

Character. — Organs representing thoracic feet, in form
of considerable-sized, cartilaginous- looking, not articulated
appendages ; generally three pairs in number. Three
pairs of foot-jaws.

Bibliographical History. — Linnaeus, in his ' Wastogota
Resa,' or tour through Westrogotha in 1747, describes a
species of Lernea, which he aftenvards named Lerntea
asettina, that evidently belongs to the family of Chondro-
canthidse. This is the first notice of any species that we
have met with, but the figure is too indifferently executed
to enable us very distinctly to refer it to any one de-
scribed. Barbut, in his ' Genera Vermium,' 1703, copies
the figure as it is, and mentions it as the Lernea that
infests the gills of the cod and ling of the Northern
Ocean. Miiller, in his ' ZoologiaDanica,' 1781, describes
and figures three other species infesting the fishes of the
Danish seas, two found on soles, and a third on the Cory-
pliaena rupestris. Delaroche, in the ' Nouv. Bull, des Sc.
de la Soc. Philom.,' 1811, describes another species, and

* AyKvpa, anchor; aud cn-ojua, mouth.

324 BRITISH ENTOMOSTKACA.

first gave to it the name of Chondracanthus, from the
cartilaginous sort of spines which cover the body.

Cuvier, in his ' Regne Animal/ figures two distinct
species, but only slightly indicates them in a note ; and
Blainville, in his Monograph of the Lerneadse, in the
' Journ. de Phys.' for 1822, describes nine more, under
the different generic names of Lernacantha, Lernentoma,
and Lernanthropus. None of these authors, however,
enter into any lengthened details with regard to the struc-
ture or habits of these curious little creatures ; but a few
years after the publication of Blainville's memoir, atten-
tion was called to their history by Nordmann, who, in
his ' Mikrog. Beitr.,' 1832, has given us much very in-
teresting and valuable information with regard to them.
He was followed by Burmeister and Kroyer, the latter
of whom has especially devoted his attention to the
anatomy and physiology of several species of the family.
Since then, Rathke has followed up these inquiries with
great diligence, and has added much to our knowledge
of the two sexes, as well as the internal anatomy of the
female.

Anatomy, Sfc. — Female. The body of these animals pre-
sents no trace of articulations, though two or three divisions
may in general be easily recognised, consisting of the head,
which has in many instances a sort of neck, and the
thorax. The abdomen is nearly quite rudimentary. The
head is small, and generally not very distinct from the
body. It is slightly convex and smooth dorsally, and has
a small groove running down the centre. In many of
the species it contracts towards its lower part, forming
a short neck before it joins the thorax.

The eyes are totally wanting. The antennae are only one
pair, rather flattened generally, and very indistinctly jointed.

Immediately beneath the antennae we see the first pair
of foot-jaws ; small, and consisting of a short but stout
basal joint, and a hard, curved claw or hook, by means of
which the animal assists in fastening itself to its prey. At

CHONDRACANTHID.E. 325

some distance from these organs, about the middle of the
head, is situated the mouth.

Rathke and Nordmann describe a pair of mandibles
attached to the mouth, and a pair of small organs, which,
according to M. Edwards, is a second pair of foot-jaws.
The mandibles are very small, and are beset along their
entire length with very fine teeth ; and the foot-jaws are
somewhat larger, and composed of a stout basal joint and
a horny, curved hook. Immediately below these we see
a third pair of foot-jaws, considerably larger than the pre-
ceding, and consisting of two tolerably large joints, and a
moveable, moderately large, and curved claw.

The thorax is connected to the head by means of a sort of
neck, which in some species is of considerable length, and
occasionally gives origin to one or two pairs of processes,
which project laterally. The thorax itself is of consider-
able size, and varies much in form and appearance; it
gives origin to several pairs of cartilaginous-looking pro-
cesses from its sides, and a pair of ovarian tubes of con-
siderable length. Between these ovarian tubes is situated
the abdomen, which is exceedingly small, indeed almost
obsolete.

Male. The males are extremely small, about half a line
long, and do not in the slightest degree resemble the
female. They are of a more or less pyriform shape, with
a very large head, an articulated thorax, and possess very
large foot-jaws. They are always found attached to tke
posterior extremity of the female, between the anus and
the right sexual aperture.

In general only one male is found upon each female,
but in some species there are two. As I have mentioned
above (p. 321), doubts have been thrown upon these little
creatures being males. Burrneister, for instance, supposes
they may be only unformed or youthful specimens. Rathke,
however, agrees with Nordmann and Kroyer, in consider-
ing them to be really males. "The circumstance," he
says, " that those beings which we find in the sexual
apertures of the female Lernese, show always in the same

326 BRITISH ENTOMOSTRACA.

species the same degree of development and structure, and
that in some species, Ckondracanthus Lophii for example,
only a single small specimen is found on each female, and
in other species, on the contrary, two small specimens are
found in the sexual apertures of a female, sufficient reason
may be found to support Nordinann's view, and to esta-
blish its truth."

Genus 1 — CHONDRACANTHUS.*

CHONDRACANTHUS, De la Roche, Nouv. Bull. Soc. Phil., ii, 1811.

Lamarck, Hist. An. s. Vert, edit. 2d, iii, 6S1.
CHONDRACANTHUS (pars}, H. Edwards, Hist. Nat. Crust., iii.
LERNACANTHA, Blainville, Journ. de Pliys., xcv, 442, 1822; Diet. Sc.

Nat., xxvi.
Desmarest, Cous. gen. Crust., 350.

Character. — Two pairs of foot-jaws prehensile, the third
nearly rudimentary. Appendages of thorax representing
the feet, in form of digitated, but not articulated, and not
setiferous lobes or tubercles. Oviferous tubes very short,
broad, and flattened.

The genus Chondracanthus was established by De la
Roche in 1811, in the 'Nouv. Bull, de la Soc. Philom./
upon a species of Lernea which he found attached to the
Zeus fader, and which appears to be characterised by its
exceedingly bizarre appearance, as if it were stuck over
with horny spines or tubercles, and having the oviferous
tubes short, broad, flattened, and nearly concealed be-
tween the elongated, terminating, lateral prolongations.

Blainville, in the 'Journal de Physique,' 1822, in his
monograph of the Lerneada?, established upon the same
species his genus Lernacantha ; but the name of Chon-
dracanthus has by most succeeding authors continued to
be retained.

* Xoj-fipof, cartilage; and nKavOn, .spine.

LERNENTOMA. 327

CHONDRACANTHUS ZEI. Tab. XXXV, fig. 1.

CHONDKACANTIIUS ZEI, De la Roche, Nouv. Bull, des Sc. de la Soc.

Philom., ii, 270, t. 2, f. 2, 3811.
Lamarck., Hist. An. s. Vert., iii, 682.
Burmeister, Nov. Act. Nat. Cur., xvii, 325.
lini'i-'tii, Icon. Regne Anim. Zooph., t. 9, f. 9.
M. Edwards, Hist. Nat. Crust., iii, 504, No. 7.
LEKNACANTHADELAR.ocHiANA,.Z?&M,wz7/e, Journ. Phys.,xcv, tab. xxvi,

f. 13, 1822.
Desmarest, Cons. gen. Crust,, 350.

Body short, and rather thick. Head rounded. Antennae
short, and rather broad. Neck narrow, short. Thorax
carrying on the under surface two pairs of small ap-
pendages, each consisting of three divisions or fingers,
and furnished laterally with three pairs of longer pro-
longations, of many divisions, the terminal one on each
side larger than the others, and embracing the oviferous
sacs. The upper part of the thorax is covered with short,
conical, sharp-pointed spines. Abdomen rudimentary.
Oviferous sacs flattened, containing many small ova.

Hob. — Found adhering to the gills of the Zeus fader,
by J. Crouch, Esq. " Dr. Leach." British Museum.

Genus 2 — LERNENTOMA.

LERNENTOMA, Elaincille, Jouru. Phys., 1822.

Desmarest, Cons. gen. sur les Crust.
ANOPS (pars), Oke>/, Lehrbuch der Naturg., 1815.
ENTOMODA (pars), Lamarck, Hist. An. s. Vrert., iii, 1816.
LEKN^EA, Midler, Zool. Dan.
CHONDKACANTHUS (pars), Ciivier, Ilegue An., 1817.

Nordmann, Mikr. Beitr.

Burmeister, Nov. Act. Nat. Cur., xvii.

Rathlce, Nov. Act., xx.

M. Edwards, Hist. Nat. Crust.

Character. — Foot-jaws and thoracic appendages as in
Chondracanthus. Oviferous tubes long, either club-
shaped and stout, or slender and twisting.

328 BRITISH ENTOMOSTRACA.

The genus Lernentoina was first established by Blain-
ville in his monograph of the Lerneadse, in the ' Journ.
Phys.,' 1822, to contain those Lernese which, as in Chon-
dracanthns, were distinguished by their having processes
or appendages taking the place of the thoracic feet, but
having long, club-shaped, oviferous sacs.

Oken, in his ' Lehrbuch der Naturgeschichte,' 1815,
had placed the several species belonging to Lernentoma
in his genus Anops ; but as that genus is loosely charac-
terised by him, and embraces several species belonging
not only to different genera, but even to different tribes,
I have preferred adopting that of Blainville. Lamarck,
in his 'Hist. Nat. An. sans Vert.,' first edition, iii, 1816,
places them in his genus Entomoda ; but as that genus
embraces also several species belonging to different fami-
lies, though it likewise has the precedence in time, I con-
sider the more restricted and better-defined genus of
Blainville as worthy of preference. Most authors, how-
ever, have described the various individuals belonging to
Lernentoina as Chondracanthi.

1. LERNENTOMA CORNUTA. Tab. XXXV, fig. 2.

LERN^A CORNUTA, Miiller, Zool. Dan., i, t. 33, f. 6 ; Enc. ineth.,

t. 78, f. 1.

ENTOMODA CORNUTA, Lamarck, Hist. Au. s. Vert., iii, 685.
ANOPS CORNUTA, Oken, Lehrbucb der Naturg., iii.
LERNENTOJIA COKNUTA, Blainville, Journ. Phys., xcv, 441, No. 6.
CIIONDRACANTHUS coRNUTUs, Cuvier, Regue An., iv, 258.

Nordmann, Mik. Beitr., ii, t. 9, f . 5, 6 (?) .

M. Edwards, Hist. Nat. Crust., iii,

500, No. 1.
HORNED LERN^EA, Shaw, Naturalist's Miscellany, viii, t. 295.

Character. — Female. Head oval, rather elongated.
Antennas flattened, of considerable size, and projecting.
Thorax elongated, club-shaped. Anterior portion narrow
for about a third of its length ; the other two thirds much
broader, and terminating posteriorly in two sharp lateral
tubercles of moderate length, and a middle one represent-

LERNENTOMA. 329

ing the abdomen, which is nearly quite rudimentary. Two
pairs only of thoracic appendages are visible, occurring
at the upper portion of the narrow part, each divided into
two digitations, and situated at a short distance from each
other. The oviferous sacs are of considerable size, cylin-
drical, and about two thirds the length of the body.
Length nearly three lines.

Male. Somewhat pyriform in shape. Head very large,
swollen. Thorax conical, divided into five segments, and
terminated by a rudimentary abdomen, armed with two
small hooks. Antennae slender, setaceous, projecting
from the anterior extremity of the head, and underneath
them a pair of hook-shaped foot -jaws. Mouth situated
far back, and provided with mandibles ; and behind the
mouth two other pairs of foot-jaws are visible. Following
these we observe two pairs of setiferous tubercles repre-
senting the feet. Length, a quarter of a line.

Hab. — Female. On the branchiae of a sole, May 2d,
1837; Ireland, W. Thompson, Esq.

2. LERNENTOMA ASELLINA. Tab. XXXV, fig. 4.

LERN^A ASELLINA, Linnaeus, Faun. Suec., 2101, 1761 ; Syst. Nat.,

edit. 12th, i, 1093, No. 4.

LERNENTOMA ASELLINA, Blaincille, Journ. Phys., xcv, 411.
LERNENTOMA TRIGLA, Blainmlle* 1. c., xcv, 441, t. 26, f. 12 ; Diet.

Sc. Nat., xxvi, 125.
Desmarest, Ccms. gen. Crust., 349.

CJIONDRACANTHUS TRIGL.E, Nori1i,n(,t,>, Mik. Beitr., ii, 116, t. 9, f. 1-4.

Burmeister, Nov. Act. Nat. Cur., xvii.
Guerht, Icouog. Regne An. Zooph., t. 9,f. 8 .
Kroyer, Tidsskrift, ii, 135, t. 3, f, 3.
M. Edwards, Hist. Nat. Crust., iii, 502.
LERN^A CAUDA DUPLICI TERETI, Linnaeus, Wastogota Resa, 171, t. 33

f. 4 a, b, 1747.
LERN.EA, Cuvier, Regne An., iii, t. 15, f. 4.

Character. — Female. Body somewhat square -shaped.

* Not Lerneomyzoti t riff la, as Kroyer erroneously quotes it (Tidsskrift, ii).

.'330 BRITISH ENTOMOSTRACA.

Head small, and situated at the end of a long and slender
neck. It is rounded at the anterior extremity, and a
little below the antennae exhibits on each side a round
lobe or tubercle. The antennae and foot- jaws are very
small. The neck nearly equals in length the rest of the
body. The thorax is broad, and of a somewhat quadran-
gular shape, with a deep indentation on each side about
the middle of its length. On the upper half we see two
pairs of prolongations or appendages, each divided into
three digitations ; and on the lower half there are three
smaller appendages, but simple, not digitated. The pos-
terior angles of the thorax are prolonged also into short
horns or appendages, which are also simple. The abdo-
men is in form of a short tubercle, with a rounded blunt
point. The oviferous sacs are of about the length of the
whole animal, of considerable size, and cylindrical.

The male is similar, according to M. Edwards, to that
of Chondracantfms (Lernentoma) cornutus.

Hab. — It is found attached to the branchiae of the
Triylce. Falmouth, J. Crouch, Esq. British Museum.

3. LERNENTOMA LOPHII. Tab. XXXV, fig. 3.

CHONDKACANTHUS LOPHII, Johnston, Loudou's Mag. Nat. Hist., ix,

81, 82, f. 16«-c, 1836.
Rathke* Nov. Act. Nat. Cur., xx, 116, t. 5,

f. 11-18, 1813.

CIIONDRACANTHUS GiBBOSus, Kroyer, Tidsskrift, i, 252, t. 2, f. 4.
CHONDRACANTHUS DELAROCHIANA (pars), M. Edwards, Hist. Nat.

Crust., iii.

Character. — Female. Body rather elongate, and some-
what gibbous. Head small, having on each side a small
horn-shaped appendage directed a little obliquely back-
wards. Antennae small, conical, and slightly curved.
Thorax divided into four portions by as many contractions.

' Rathke has described the same species under the same name as Dr.
Johnston has applied to it, but evidently without knowing that the name
had already been vised.

ANCHORACAKPACEA. 331

The first, narrow like a neck, having on the upper portion
a short spine, and on the under surface a pair of appendages
or prolongations of two divisions or digitations. The
second is somewhat quadrilateral, with, on the middle
line of the back, two conical tubercles, and on the sides
two others, the upper pair the longer ; and having on the
under surface a pair of appendages of two digitations.
The third part is larger than the preceding, and has the
same tubercles and prolongations, and in addition, a small
spine on the superior portion, and in the mesial line of
the under surface. The fourth portion is rather the
largest, with two horns or tubercles on the upper surface,
a third on the median line of the under surface, and on
each side a long terminal prolongation, rather blunt.
Abdomen in form of a short tubercle in the centre of the
posterior part of thorax. Oviferous tubes very long,
slender, and twisted. Length, six lines and a half;
breadth, two lines and a half.

The male is very similar to that of the Chondr acanthus
cornutus already described.

Hab. — Found on the Lophius piscatoriiis, in the
pouches; Dublin, December 1839. Belfast, November
1841 ; W. Thompson, Esq. Scotland and coast of
Devon, Leach. British Museum. Falmouth, J. Crouch,
Esq. British Museum.

TKIBE Z—ANCHORACARPACEA*
LERNEOPODIENS, M. Edwards, Hist. Nat. Crust., iii.

Character. —Attached to their prey by means of two
long appendages which arise from the thorax. They
unite together either at the base or near the tip only, and
terminate there in a rounded knob like a button, by
means of which the animal maintains its hold of the part
to which it has attached itself. No thoracic feet, or they
are represented by these arm-shaped appendages.

rr, anchor; and Kapiroc, arm.

332 BRITISH ENTOMOSTRACA.

Males in general differ very much in appearance from
the females, being greatly smaller and unattached.

Family LERNEOPODAD.E.
LERNEOPODIENS (pars), M. Edwards, Hist. Nat. Crust., iii.

Character. — Arm- shaped appendages long, wide apart
from each other at their base, and united only at the tip.

Genus LERNEOPODA.*

LERNEOPODA, Blainville, Journ. Pliys., xcv, 442, 1822.

Kroyer, Tidsskrift, i, 207.

M. Edtcards, Hist. Nat. Crust., iii, 514.

W. Thompson, Ann. Mag. Nat. Hist., xx, 248.

Rathke, Nov. Act., xix.
LERNJJA, Gisler, Linnccas, Grant, Retzius, $-c.

Character. — Female. Body generally elongated, oval.
Head short and thick. Two pairs of foot-jaws, well-
developed, and placed near each other. External ovaries
of moderate length and cylindrical.

Male. Body divided into two nearly equal portions of
an ovoid shape ; one representing the head, the other the
thorax. Much smaller than the female.

The genus Lerneopoda was established by Blainville,
in the 'Journal de Physique/ in 1822; and was after-
wards adopted by Nordmann in 1832, Burmeister in
1835, and Kroyer, in his 'Tidsskrift/ in 1837 ; but the
first notice taken of any species appertaining to the genus
was by Gisler in 1751, who, in the twelfth volume of the
' Acta Suecica,' describes and figures a species of Lernea
found by him on the salmon, and which he called "Pedi-
culus salmoms or Lax-lusen."\

Linnseus, in his 'Fauna Suecica,' 1761, describes this
species as the Lerncea salmonea, and repeats it in his

f Aipmiioc, belonging to Lernea : and TTOVC, foot,
t " Salmon louse."

LERNEOPODA. 333

' Syst. Nat./ 1766. The same little animal was a few
years afterwards described as British : the Rev. Charles

i/

Cordiner having figured it in 1780, in his 'Antiquities
and Scenery of the North of Scotland/ as occurring in
the gills of the salmon in the rivers of that country,
especially when the fish is "foul."

Another species was afterwards mentioned by the arctic
voyager Scoresby, in 1820, adhering to the Greenland
shark. Several specimens were taken by him attached to
the eye of that animal, and brought home for examination.
It buries its arm-shaped appendages in the substance of
the eye to the depth of nearly a fourth part of their length,
and hangs out externally. The sharks thus attacked seem
to be rendered blind by their pigmy assailants. " The
sailors/' says Captain Scoresby, "imagine this shark is
blind, because it pays not the least attention to the pre-
sence of a man, and is indeed so apparently stupid, that
it never draws back when a blow is aimed at it with a
knife or lance." (Arctic Regions, p. 539.) The speci-
mens brought home by Captain Scoresby were ultimately
placed in the hands of Dr. Grant, and the species was
described by him in Dr. Brewster's ' Edinburgh Journal
of Science/ in 18:27, under the name of Lerncea elonyata.

A species was also figured and described by M. Mayor,
in the 'Bulletin de la Societe Philomathique/ in 1824;
and Kroyer, in his ' Tidsskrift/ describes four more new
species, and found the male of one, of which he gives a
figure.

The young have not yet been seen.

1. LERNEOPODA ELONGATA. Tab. XXXV, fig .5.

LERN.EA ELONGATA, Grant, Brewster's Edinburgh Journ. of Sc., vii,

14-7, t. 2, f. 5,1827.
LERNEOPODA ELONGATA, Kroyer, Tidsskrift, i, t. 2, f. 12, t. 3, f. 3 a.

ALEdti'ards,]t:List. Nat. Crust., iii, 515.

THE EYE or THE GREENLAND SHARK, Scoresby, Arctic Regions, i,

538, t. 15, f. 5.

Description.--^^ head is very distinct, of a horny

334 BRITISH ENTOMOSTRACA.

texture, ovate, depressed, broad at the base, and obtusely
pointed in front, resembling very much the shape of thebody
of the common spider-crab. The second pair of foot-jaws
is large and well developed, consisting of a large, rounded,
oval, basal joint, and a more slender, curved, hooked,
terminal one, with a pretty strong tooth on its inner edge.
The head is united to the body by a short, narrow neck.
The thorax is long and narrow, of a somewhat club-shaped
form, and gives origin to two long cylindrical arms, which
considerably exceed the length of the body. At the pos-
terior portion, which is somewhat truncate, we see two
small lobes ; and on each side of these spring the ovaries,
which are about the length of the entire body, thick,
straight, and cylindrical.

Length of whole animal, nearly three inches. Head,
one line and three quarters. Body, seven lines and a half.
Arms, one inch and one line. Ovaries, one inch and one
line and a half.

Hal). — A specimen of this arctic species was found at-
tached to the eye of a shark caught on the English coast,
and brouo;ht to London in the winter of 1848. Mr.

O

Yarrell, to whom I am indebted for the specimen, took it
himself from the eye of the shark, but unfortunately it
was not perfect. Its arm-shaped appendages were inserted
into the cornea, to the depth of nearly a fourth of their
length.

2. LERNEOPODA GALEI. Tab. XXXV, fig. 7.

LEKNEOPODA GALEI, Kroyer, Tidsskrift, i, 272, t. 3, f. 5 a-f.
M. Edwards, Hist. Nat. Crust., iii, 516.

Character. — Female. The head is oval, depressed, and
of a hard, horny substance. The thorax is long, rather
slender, and somewhat cylindrical, narrow where it is at-
tached to the head, and broadest at its posterior extremity.
The arms are slender, and nearly the length of the thorax.
At the posterior extremity of the body are two small lobes,

LERNEOPODA. 335

between which, on the middle line, is a small tubercle,
representing the abdomen. Ovarian tubes of moderate
length, not quite equal to length of thorax.

Length of the whole body, including arms, about three
fourths of an inch.

Male. Body divided into two portions, of an ovoid
form, and nearly of equal size. The upper half represents
the head, and carries a pair of antennae, and two pairs of
foot-jaws of considerable magnitude. The lower half,
representing the thorax, has at its posterior extremity
two sub-globular appendages, a little longer than those
in the female.

Hab. — Female. Attached to the cavity posterior to
the vent of the Squalus galeus, Belfast, December 1839,
W. Thompson, Esq.

3. LERNEOPODA SALMONEA. Tab. XXXV, fig. 6.

PEDICULUS SALMONIS, Gisler, Kongl. Svensk.Vetensk. Acad.Hadliug.,

xii, 171, t. 8, f. 1-5, 1751.

LEEN^EA SALMONEA, Linnaeus, Faun. Suec., edit. 2d, 509, No. 2102,

1761; Syst. Nat., edit. 12th, 293; Lernsea,No.3.

ConJiacr, Antiq. and Seen, of the N. of Scotland,

7, 8, t. 6, f. 2.

0. Fabricius, Faun. Groenl., 337.
Miiller, Zool. Dan. Prod., 2711.

ENTOMODA SALMONEA, Lamarck, Hist. An. s. Vert., edit. 2d, iii, 686.
LERNEOPODA SALMONEA, Blainville, Jouni. Phys., 1822, 127.

Mayor, Bull, des Sc. Soc. Philom., 1824, 24.
LERNEOPODA CARPIONIS (?), Kroyer, Tidsskrift, i, t. 2, f. 6.

M. Edwards, Hist. Nat. Crust., iii, 515.

Linnseus's description of this species, as far as it goes,
is very good. " Body obovate, thorax obcordate, the two
arms linear, approximated." The head is rather small,
somewhat bulging out at the back part, broader there,
and rather sharp-pointed at the anterior extremity. From
the base of the head spring the two arms, which are
rounded, and slightly shorter than the body. The thorax

336 BRITISH ENTOMOSTRACA.

is pyriforra and short, and at its lower extremity we see
two minute eminences. The ovarian tubes are of con-
siderable thickness, cylindrical, and about the same length
as the whole animal.

The colour of the animal is white. Length, about
half an inch.

Hob. — Gills of the salmon, London market, W. B.

Family 2-ANCHORELLADyE.
LERNEOPODIENS (pars), M. Edwards, Hist. Nat,. Crust., iii.

Character. — Arm-shaped appendages very short, and
united to each other from the base, so as to resemble a
single organ.

Genus ANCHORELLA.

LERN.EA, Strom, Soudrnoer ; Lctmarck, Mi'>ll<-r, Johnston.

ANCHORELLA, Carter, Eegue An., 1817 ; Nordmann, Burmeixter, Kroyer,

M. Ei.lwrilx.

CLAVELLA (pars), 0fo>/,Lehrbuch,lS15 (notdwfz^EegneAn.jiior Kroyer}.
LERSEOMYZON, Elainmlle, Desmarest.

Character. — Female. Body in general short, and
somewhat swollen. Head small, and situated at the ex-
tremity of a long neck, which is generally curved back-
wards. Two pairs of foot-jaws well developed, and a
third rudimentary. Antennsc rudimentary. Ovarian
tubes of moderate length, and cylindrical.

The male differs in appearance very much from the
female, and is very small.

The genus Anchorella, as established by Cuvier in 1817,
embraces the Lerneadse of this division, in which the
arms are short, and united to each other from the base.
A species is figured by Strom, in the 'Physiske og
Oeconomisk,' &c., which appears to be the first described,

ANCHORELLA. 337

and which Cuvier has named Anchor etta adunca. The
name of Lerneomyzon was proposed by Blainville, in his
Monograph, but the term Anchorella, as having the
precedence in time, has been generally adopted by suc-
ceeding authors.

1. ANCHORELLA UNCINATA. Tab. XXXV, fig. 9.

LERMA UNCINATA, Miller, Zool. Dan., i, t. 33, f. 2; Enc. meth., Vers,

t. 78, f. 7 (copied from Mailer}.

Lamarck, An. s. Vert., edit. 1st, iii, 231.

/o/m^o», London's Mag. Nat.Hist.,viii, 565, f. 53.

Thompson, Report ou Fauna of Ireland, div. In-
vcrtcbrata, in Report of Brit. Ass., 1843, 270.

— Fabricius, Faun. Graulaud., 338, No. 328.
„, , , ,, ,. . ,, .

— Tin-ion s Gmielm, iv, 114.

Bosc, Hist. Vers, i, 59, t. 1, f. 4.

SCHISTURUS UNCINATUS, Oken, Lehrbucli der Naturg., B, iii, p. 183.
CLAVELLA UNCINATA, Oken, 1. c.

LEIINEOMYZON UNCINATA, Blainville, Diet. Sc. Nat., xxvi, 122.
ANCHORELLA UNCINATA, Nordmann, Mikr. Beitr., ii, 102, t. 8, f. 8, 9,

t. 10, f. 1-5.

Kroyer, Tidsskrift, i, 290, t. 3, f, 8.
M. Edwards, Hist. Nat. Crust., iii, 519.
ANCHORELLA LAGENULA, Enc. Brit., edit. 7th, xxi, t. 502, f. 14.

Character. — Female. The body of the animal is thick,
oblong, of a milk-white colour, smooth, and opaque.
Head very small, situated at the extremity of a long,
slender neck, which has a wrinkled appearance, and is
nearly the length of the thorax. The arms spring from
the upper portion of the thorax, and are rather short,
terminating in a rounded knob or button. At the pos-
terior portion of the thorax there is on the middle line a
small protuberance, representing the abdomen. The
ovarian tubes are cylindrical, straight, smooth, and about
the length of the body. Length, from six to eight lines.

Male. Body globular, terminated in front by a small,
conical eminence, at the extremity of which is the mouth,
and having at its base one pair of rudimentary appen-
dages, and a pair of rudimentary foot-jaws. On the

22

338 BRITISH ENTOMOSTRACA.

middle of the body, on the inferior surface, there are two
pairs of large, hooked, claw-like members. Length, one
fourth of a line.

Hub, — Female. " It fixes itself to the fins and gill-
covers of the cod and haddock, .... and is most probably
the most common species of our seas." (Johnston.) At-
tached to the gills of the cod, Ireland, May 1837 ; to the
gill-covers of a whiting, April ]837; W.Thompson, Esq.
In the latter specimen the ovaries are considerably longer
than the thorax.

2. ANCHORELLA RUGOSA. Tab. XXXV, fig. 8.

ANCHOKELLA KUGOSA, Kroyer, Tidsskrift, i, 284, t. 2, f. 7.

J/. EJirards, Hist. Nat. Crust., iii, 519.

Character. — Body nearly of a square shape, a little
emarginated on each side. Head small, neck slender,
and nearly cylindrical. A rounded tubercle on middle
line represents the abdomen. Ovaries rather larger than
the thorax, nearly cylindrical, or slightly club-shaped.
Length about three lines.

Hob. — From the mouth of a Gadus cellarius, taken at
Larne ; W. Thompson, Esq.

TRIBE Hl—ANCHORACERACEA*
LERNEOCEBIENS (pars), M. Edwards, Hist. Nat. Crust., iii.

Character. — Females. Attached to their prey by the
anterior extremity of their body only, thrusting the en-
tire head into the tissues of the animal to which they
adhere, and being retained there by means of a kind
of horns, which are various in form, and spring from the
posterior part of the head. No antennas. Only one pair
of foot-jaws, which is simple and hooked. Feet either
very small or often wanting altogether.

* Ayicvpa, anchor, ami nepac, horn.

LERNEONEMA. 339

Males. Very small. Body globular, and more imper-
fect than in the preceding tribes, having no distinct thorax,
and no rudiments of feet behind the appendages which
represent the foot-jaws.

Family 1— PENELLAD.E.
LERNEOCERIENS (pars), M. Edwards, Hist. Nat. Crust., iii.

Character. — Several pairs of feet situated on the under
surface of the body near the head, but very small and
rudimentary.

Genus LERNEONEMA.

LERN^EA, Sowerby, British Miscellany.

Blainville, Turtou's British Fauna.
LERNEOCERA, Blainville, Journ. Phys., xcv.
LERNEOPENNA, Lesueur, Journ. Acad. Philad., iii.
LERNEONEMA, M. Edwards, Hist. Nat. Crust., iii, 524.

Character. — Body long, slender, narrowed anteriorly
in the form of a neck, which is terminated by a swollen
head, furnished with two or three simple, curved, horn-
shaped appendages. Abdominal portion of body of in-
considerable length, and simple. Oviferous tubes long
and slender.

History. — The genus Lerneonema was established by
M. Edwards, in his ' Hist. Nat. Crust/ (iii), to receive
some species of Lerneadse, resembling considerably the
Pennatula of Linnaeus (Penella, Oken), but which are
destitute of the peculiar plumose abdomen which charac-
terises distinctly this latter genus.

Baker seems to have known a species belonging to the
genus, and describes it as British, in the ' Philosophical
Transactions' for 1744. He calls it the " Eye-sucker," and
says " it was found fixed by the snout to the eyes of a sprat."
His figure is very bad, and no doubt difficult to be recog-
nised. We must remember, however, that in removing

340 BRITISH KNTOMOSTRACA.

the Lernea? from the animals to which they are attached,
the head is often torn away, and that the ovarian tubes,
which in this genus are long and slender, may easily like-
wise be mutilated, and that one of these may be readily
torn off. If we then examine a species of Lernconema
sprafta, and compare it with the figure given by Baker,
and read his description, we shall see at once that the
animal described by him at p. 35 of vol. xliii, and repre-
sented at t. i, f. 2, 3, is clearly an individual of that
species without the head, and with only one ovarian tube,
which is represented as the body, " somewhat thicker than
a hog's bristle," while the real body is represented as the
head, the neck being the " snout."

In 1806, Mr. Sowerby again described this parasite of
the sprat, in his ' British Miscellany,' and gives a figure
of it, of the natural size in situ, attached to the eye of the
little fish, and part of a magnified sketch, representing the
head and neck, detached. These figures of Mr. Sowerby
have apparently given rise to an amusing mistake on the
part of M. de Blainville. How he saw the original figures
of Sowerby it is difficult to say ; perhaps in the possession
of Dr. Leach. He has, however, in his paper in the
' Journal de Physique,' so often quoted above, reproduced
the two figures, the one in situ of the natural size, the
other the magnified sketch of the upper portion only, and
described them as two distinct species ! The only infor-
mation, he adds, that he has concerning the two species is,
" that they are copied from MS. drawings of the English
voyage to the Congo !" The figure of the one in situ he
names the Lerncea cydopliora, the eye of the sprat of
Sowerby's figure being described as the round head of the
Lernea ! while the magnified figure he merely designates
as a species of " Lerneide articulee" the outline of the
unfinished short portion or commencement of the body of
Sowerby's sketch being taken by him as the oviferous
tubes !

One or two other species have since been described,
but the number known is yet but few.

LERNEONEMA. oil

1. LERNEONEMA SPRATTA. Tab. XXXV, nV 10.

" O

LERN.EA SPRATTA, Sowerby, British Miscellany, t. 68, 1806.

LERN YEA cvcuofHO-R^Blainville, Jouru.de Phys.,xcv, t. 26, f. 7; 1822.

LERNKIDE ARTicuLfiE, Blaitiville, 1. c., f. 17.

LERNEONEMA MONILLARIS, M. Edwards, Hist. Nat. Crust., iii, 525,

t. 41, f. 5, 1840.
T/iompsoH, Report Brit. Assoc. for Advance.

Sc. 1843, 270.
THE EYE-SUCKER, Baker, Phil. Traus., xliii, 35, t. 1, f. 2, 3,

Body slender, considerably larger at the posterior ex-
tremity. Head of tolerable size, rounded, and provided
with two narrow, rather hooked horns at its back part,
directed backwards. The head is connected to the body
by means of a long and very slender cylindrical neck,
which is furnished with about a dozen constrictions, which
make this part of the body appear as if it were beset
with an equal number of rings or knobs.

A short distance beneath the head it is very narrow,
gradually increasing in size as it joins the body. Abdo-
minal portion small, blunt, and obliquely truncate. The
ovarian tubes are very long and slender, about as long
again as the whole body of the animal.

Length of the body about an inch ; ovaries, one inch
and a half.

Hab. — Found attached to the eye of a sprat. London
market, Nov. 1848 ; Mr. W. Wing.

~. LERNEONEMA ENCRASICOLI. Tab. XXXV, tig. 11.

LERN.EA ENCRASICOLI, Turton, British Fauna, i, 137, No. 108, 1807.

Body cylindrical, shorter than the preceding, and of
about the same size at both extremities. The neck is
long and slender, quite smooth, and destitute of the con-
strictions which mark so decidedly the preceding species.
The neck is white, and the body is of a brown, horny
colour.

342 BRITISH ENTOMOSTRACA.

The abdomen is like that of the preceding, and the
ovarian tubes are long and slender, at least twice the length
of the body. Turton describes the ovaries as " clear white."
Perhaps they may be so in the living animal, but in the
specimens preserved in spirits, they are of exactly the
same colour as the body. In one specimen, however, one
of the tubes is broken, and the ova have escaped, and in
this the tube is white.

Length of the body about half an inch ; ovaries, fully
one inch.

Hob. — Attached to the body of a sprat, from Yonghal ;
R. Ball, W. Thompson, Esq. " Found attached to the
bodies of the Clupca encrasicolus and sprattus frequently,
in Swansea Bay ;" W. Turton, M.D. Attached to the
body of a sprat ; Mr. J. Doubleday. British Museum.

Family 2— LERNEOCEKADJB.
LEENEOCEEIENS (pars), M. Edwards, Hist. Nat. Crust.

Character. — No vestiges of feet on under surface of
body, nor any appendages representing them.

Genus 1 — LERNEOCERA.*

LERN.EA, Linneeus, Earbut, Hermann, Lamarck.
LERNEOCEKA, Blainville, Joum. Phys., 1822.

— Desmarest, Nordmann, Birrmeister, Kroyer, Lesueur,

M. Edwards.

Character. — Body long and slender; head furnished
with horn-shaped appendages, which are simple and sym-
metrical in form. Ovarian tubes straight, and of moderate
length. Abdomen very small.

Linnaeus was the first who noticed any of the animals

'* Aepraiog, belonging to Leruea, and Ktpac, horn.

LERNEOCERA. 843

belonging to this genus. In his 'Fauna Suecica,' 1746,
he describes a species found in Sweden on the carp ; a
species which Barbut, in 1783, ascertained to be British.
Hermann also, in 1783, describes and figures another
species, and several have since that time been added to
the list.

Blainville, in his Monograph, so often quoted, formed
the genus Lerneocera to receive several species which had
then been described, and amongst others the species found
by M. Surriray, of Havre, which led to the first notice of
the young of the Lerneadse.

The genus, as established by Blainville, contains two
species, which have been separated from it by Kroyer and
M. Edwards; but still it has been retained in a restricted
sense by all succeeding authors.

LERNEOCERA CYPRINACEA. Tab. XXXV, fig. 13.

LERNJSA CYPRINACEA, LiniKeus, Faun. Suec., No. 2100, t. 2, f. 2100 ;

Syst. Nat., edit. 12th.
Barbut, Geu. Vermium, t. 7, f. 3.
Titrton, Brit. Faun., 137, No. 105.
Lamarck, An. s. Vert., iii, 230; Euc. im'th.,

Vers, t. 78, f. fl.

LERNEOCERA CYPRINACEA, Blainville, Journ. de Phys., xcv, 377.

Desmarcst, Cons. gen. Crust., 346.
Burmeister, Nov. Act. Nat. Cur., xvii,

309,1 HA, f. 1-3.
M. Edwards, Hist. Nat. Crust., iii, 527.

Head furnished with four horn-shaped appendages,
which are somewhat long and slender. The two outer or
posterior are bifurcated ; the anterior simple.

The thorax is very slender anteriorly, forming a long
neck, but becomes much broader posteriorly, and when it
terminates in the small abdomen, appears obliquely trun-
cate. The oviferous tubes are cylindrical, and rather long.
The length of the whole animal is about eight lines.

Hab.— -" Found on the sides of the carp, bream, and

344 BRITISH ENTOMOSTRACA.

roach, in many of our ponds and rivers, in great abund-
ance." (Barbut.) I have not seen any specimens of this
species.

Genus 2 — LERNEA.

LERN^EA, Limueus, Midler, 0. Fabricius, Oken, Citvier, Lamarck, Burmeister,

Kroyer, M. Edwards.
LERNEOCERA, BlainviUe, Norclmann.

Character. — Body more or less twisted, and outre in
appearance. Head furnished with horn-shaped append-
ages, which are irregularly branched. Ovarian tubes
twisted into round masses, and placed under the posterior
portion of the body. Abdomen of considerable size.

The genus Lernea is now restricted within very small
limits. Establishedby Linnaeus upon i\\Q Lernea branchialis,
it is at the present day confined to that species and one or
two others.

Blainville retained the genus Lernea, however, for some
other species, some of which, as Lernea cydopltora (vide
supra, p. 340), are inadmissible altogether, and others, as
Lernea Basteri, founded upon a figure given by Baster,
are very doubtful. The name Lernea was retained by
him, he says, " for those species which have no trace of
appendages to either the head or the body ; those, in fact,
which are most deformed." Burmeister, Kroyer, and
M. Edwards, however, agree in referring the genus to the
species first described by Linnaeus as the type, and have
assigned to it its characters accordingly.

LERNEA BRANCHIALIS. Tab. XXXV, fig. 12.

LEKN.EA BRANCHIALIS, Linnaeus, Syst. Nat., edit. 12th.
Lamarck, An. s. Vert, iii, 2-±0.
Ciicier, Regiie Au., iii, 256.
— Burmeister, Nov. Act., xvii.

Gwerin, Icon. Re.gne An. Zoopli., t. 9, f. 1 ;
Encyc. Britann., edit, ?th, xxi, t. 502, f. 13.

LERNEA. 345

LEENEA BRANCHIALIS, Kroyer, Tidsskrift, i, t. 3, f. 10 (?).

Oken, Lelirbuch der Naturg., t. 7.
M. Edwards, Hist. Nat. Crust., iii, 528.
Thompson, Report Brit. Assoc. for Advanc. Sc,

1843, 270.
LERNJEA GADINA, Miiller, Zool. Dau., iv, 65, t. 118, f. 4.

0. Fabricius, Faun. Gro3iil., 339.
LERNEOCERA BRANCHIALIS, Blainville, Journ. de Phys., xcv, 370,

tab. 26, f. 1, 1 a.
Nordmann, Mikr. Beitr., ii, 130.
LERN^EA, Strom, Phys. og Oecou. Besk., t. 1, f. 18.

«

Head rounded, and furnished with three horn-shaped
appendages, each of which is divided at the tip into three
short branches.

The anterior portion of the thorax is long, cylindrical,
and very slender, like a long narrow neck, while the body
itself is very much swollen in the middle, and abruptly
twisted upon itself in the form of the letter S.

The abdominal portion of the body is long, blunt at ex-
tremity, and of considerable size. The ovarian tubes are
slender, and very much twisted.

The whole animal is about an inch and a half in length,
and is of a very firm consistence, being hard and horny.

Hob. — Gills of the cod. Belfast Bay, January 1844
and 1848 ; W. Thompson, Esq. Dublin ; communicated
to Mr. Thompson by Mr. Glennon, in 1839.

346

BRITISH ENTOMOSTRACA.

APPENDIX.

A.

CYCLOPS QUADR1CORNIS.

THE varieties of this protean species are many, and are
well worthy of being carefully studied. Since the de-
scription of this species and its varieties was in the
hands of the printer, I have been favoured with a letter
from Dr. Beverley R. Morris, of York, containing sketches
of the caudal segments of four different varieties obtained
by him in the neighbourhood of that city. In one, the
two long middle setse of the tail are plumose to the ex-
tent of a little more than half their length, while the
external short ones are not plumose at all. In a second
variety, the two middle setae are plumose for more than
two thirds of their length, while the external are plumose
throughout their whole extent. In a third variety, the
two middle setae are plumose throughout nearly their
whole length, and the external entirely so. While in a
fourth, none of the setae appear plumose in any portion
of their extent. " These setae," writes Dr. Morris, " I
have been very careful to feather accurately. ... I
have been very careful," he adds, " to measure as accu-
rately as I could, the length, &c. of the different parts,
and I think they may be depended upon. They were
also all verified by a friend of mine who is with me ex-
amining the water of this district." Mr. Halliday also
informs me that a variety occurs frequently in Ireland in
which the tail setae are not plumose.

APPENDIX. 347

B.

CAMPTOCERCUS FURCATUS.

The figures of this species, represented in Tab. XXX,
figs. 4, 5, 6, made by Mr. Salter, were accompanied by
some very interesting notes, from which, with Professor
Bell's kind permission, I make the following extracts :
" It is scarcely more than visible to the naked eye. Its
head and shoulders are covered with a single case, which
seems a sort of carapace ; below this are three imbricated
rings with concave edges, looking towards the tail, their
angles projecting and forming sort of teeth. To the last
of these is appended the tail, composed of six pieces,
flexible, capable of lateral and, I think, vertical movement.
In the centre of the front of the head is a reddish-purple
spot, which shines very much in some lights, and looks
like a single eye. The most remarkable thing about this
little creature is its extraordinary power of movement,
which is well provided for by three pairs of strong oar-
like legs, which it casts behind it with great force, throwing
itself forward with surprising velocity, and outstripping
even the little sand-hoppers that hunt it. These legs,
when in a state of rest, are bent up under it, and when
it means to throw itself forward, it bends backward that
part of its leg which pointed forward, keeping the other
part in the same direction ; thus ' a' is brought to ' b',
'c' to 'd,' and 'e' to 'f,'* the oblique direction of the
other part being, as I said, still maintained. As these
legs are webbed with hairs, the three present a broad
surface against the water. When the extension is com-
pleted, I have no doubt that the muscular action which
kept the fixed direction of this last joint is relaxed, and
it is drawn up in such a way as shall present the least
resistance to the water. There are also two little pro-

* This refers to a slight sketch of these organs iu position, made by Mr.
Salter on the margin of the letter.

348 BRITISH ENTOMOSTRACA.

cesses like rudimentary legs, rising from beneath the first
joint of the tail." At this time Mr. S alter had not seen
a specimen with ova. Shortly afterwards, however, he
had an opportunity of examining a female loaded with
eggs, upon which he remarks : " Another use, perhaps
the especial use, of these two little appendages at the
base of the tail seems to be shown ; their position exactly
fits them to become a means of supporting and keeping
in its place the cluster of eggs. Now with regard to the
eggs themselves, the great size of the cluster, and the
unyielding nature of the integuments of the animal, seem
to be the causes of their external position. I think the
cluster consists of two layers, the one continuous, the
other with an intermission down the middle, forming a

O

sort of fossa for the tail. You will see from the figure
(f. 4 a] that it has a more semi-transparent line down the
middle, corresponding in size with the tail, and in the
same position. Doubling then the number of a single
layer, and subtracting for the intermission (40-|-40 — 10),
the number of ova would be about 70. Its abdomen,
for such its tail clearly is, is evidently simple, and merely
bifurcated at the end. It has a canal, the contents of
which had a very singular and regular up-and-down
movement, synchronous with what appeared to be a cir-
culatory or respiratory movement of the viscera near the
head."

INDEX.

Acanthocercus, 103.

curoirostris, 103.
Acroperus, 14, 123, 129.

karpae, 129.

nanus, 130.
Alona, 14, 123, 131.

ovata, 133.

quadraugularis, 131.

reticulata, 132.
Altcutha, 14, 198, 210.

depressa, 216.
Amymone Baccha, 205.

xati/ra, 205.

Anchoracarpacea, 15, 331.
Auchoraceracea, 15, 338.
Anchorastomacea, 15, 323.
Auchorclla, 15, 336.

lagenula, 337.

rugosa, 338.

uucinata, 337.
Aiichorelladse, 15, 336.
Animaletti aquatici, 90.
Auomalocera, 14, 218, 229.

Patersonii, 229.
Anops, 327.

cornuta, 328.
Anthosoma, 15, 296.

Smithii, 299.
Anthosomada3, 15, 296.
Apodidse, 14, 18.
AIIOY2, 29.
Apus, 14, 18, 29.

cancriibrinis, 30.

Montagui, 30.
Argulidre, 15, 242.
Argulicns, 242.
Argn.lina, 242,
Ai-'gulus, 15, 242.

argulus, 255.

char on, 255.

delphimus, 255.

foliaceus, 255.
Arpacticus, 14, 212.

chelifer, 212.

Arpacticus nobilis, 214.
Artemia, 14, 54.

salina, 61.
Artemis, 54.

salinus, 61.
Artemisus, 54.

salinus, 61.
Aspidostraca, 16.
Aster ope, 176.

Bairdia, 163.

siliqua, 171.
Binoculus, 29, 242, 269.

cauda biseta, 30.

g aster ostei, 256.

pal ust r is, 30.

piscimis, 276.
Bitestaces, 138.
]iopyrid<e, 289.
Bosmina, 14, 89, 105.

cornuta, 105.

longirostris, 105.
Brancliiopoda, 14, 17.
Branchiopodes, 16.

y ranges, 138.

e^tfwj, 17.

Lamellipedes, 17.

parasites, 240.
BrancMopteres, 16.
Branchipidcs, 38.*
Branchipiens, 38.
Braiichipodidse, 14, 38.
Branchipus, 39, 54.

cancriformis, 30.

chirocephalus, 53.

conchiformis primus, 93.

diaphamis, 53.

paludosus, 53.

Prevostii, 53.

salinus, 61.

stagnalis, 54.
Branchipusidse, 38.
Brine-worm, 61.

350

INDEX.

Calanus, 227.

FinmarcMaiiws, 228.
Cctif/acea, 240.

Caligidse, 15, 256, 281, 289, 296.
Caligina, 256.
Caligus, 15, 268-9, 273, 286, 296.

bicolor, 288.

bicolor, var. 289.

ceutrodonti, 272.

diaplianus, 269.

hippoglossi, 276.

imbricatus, 299.

Miilleri, 271.

Nordmannii, 275.

pectoralis, 275.

rapax, 270.

Smithii, 299.

Stromii, 274.

vespa, 274.
Camptocercus, 14, 123, 128.

macrourus, 128.
Cancer, 36, 39, 54.

dejn^, 36.

(Gammarellus) bipes, 36.

paludosv.s, 54.

sal in us, 61.

stagnalis, 54.
Caiidona, 14, 151, 159.

Candida, 160.

detecta, 161.

hispida, 161 .

lucens, 160.

reptans, 160.

similis, 162.
Canthocampus, 204.
Caiithocamptus, 14, 204.

furcatus, 210.

minutus, 204.

minuticornis, 211.

Stromii, 208.
Canthocarpus, 204.'

furcatus, 210.

minuticornis, 211.

staphijlinus, 205.

Stromii, 208.
Carcinoida, 182.
Cecropida?, 15, 289.
Cecropina, 289.
Cecrops, 15, 289.

Latreilleii, 293.
Cephaloculus, 111.

stay norum, 112.
Cetochilida3, 14, 233.
Cetochilus, 14, 233.

Cetochilus septeutrioualis, 235.
Ckalimus, 15, 268, 278.

Scombri, 279.
Chirocephalus, 14, 39.

diapbaims, 53.

Prevostii, 53.

Cbondracautbidse, 15, 323.
Chondracanthiens, 323.
Chondracanllius, 15, 326-7.

cor nut us, 328.

Delarochiana, 330.

gibbosus, 330.

Lophii, 330.

^z^fe, 329.

Zei, 327.
Chydorus, 14, 123, 125.

globosus, 127.

Miilleri, 126.

sphsericus, 126.
Cladocera, 14, 62.
Cladoceres, 62.
Clavella, 336.

uncinata, 337.
Copepoda, 14, 182.
Cormostomata, 240.
Croplii/ropoda, 138, 182.
Crustaces sessiliocles, 16.

suceurs, 240.
Cyclopacea, 182.
Cyclopida3, 14, 183.
Cyclopidees, 183.

Cyclops, 14, 198, 204, 212, 216,

219, 227.
Cyclops agilis, 202.

armatus, 212.

bistriatus, 203.

brevicornis, 208.

castor, 219.

e&f/jfw, 212.

ceerulem, 219.

depressus, 216.

Finmarchicus, 228.

furcatus, 210.

Geo/royi, 199.

me r mis, 211.

Johnstoni, 212.

lacinulatus, 220.

longicornis, 228.

lucidulus, 203.

minuticornis, 211.

minutus, 204.

obsoletus, 203.

phaleratus, 203.

pictus, 203.

INDEX.

351

Cyclops pulchellus, 203.

quadricornis, 198, 202, 203.

rubens, 220.

stapfiylinus, 205.

Stromii, 208.

vnlffaris, 199-203.
Cyclopsind, 204, 219.

castor, 220.

fit realm, 210.

sfitpltylinits, 205.
Cyprella, 176.
Gypridacea, 138.
Cyprides, 139.
Cyprididse, 14.
Cypridina, 14, 163, 174, 176.

Brenda, 181.

Mac Andrei, 179.
Cypridinadse, 176.
Cypris, 14, 139, 151.

aurantia, 159.

Candida, 160.

clavata, 157.

compressa, 154.

detecta, 161.

elliptica, 158.

elougata, 156.

fusca, 154.

gibbosa, 156.

hispida, 161.

Joaima, 155.

lucens, 160.

lucida, 160.

minuta, 155.

monacha, 153.

ntibilosa, 153.

pellucida, 160.

pubera, 152.

punctata, 154.

reptans, 160.

seila, 158.

strigata, 157.

tenera, 154.

tristriata, 152.

vidua, 152.

Westwoodii, 156.
Cyproides, 138, 139.
Cy there, 14, 163, 174.

acuta, 173.

alba, 170.

albo-maculata, 169.

angustata, 172.

aurautia, 171.

convexa, 174.

flavida, 168.

Cythere impressa, 173.

inopinata, 172.

Minna, 171.

nigrescens, 171.

pellucida, 173.

quadridentata, 173.

reniformis, 169.

variabilis, 170.
Cythereis, 14, 174.

antiquata, 176.

Jonesii, 175.

Whiteii, 175.
Cytheridse, 162.
Cytherina, 163-74.
Cytherinen, 162.

Daphne, 89.

crystallina, 107.

mucronata, 99.

pulex, 90.

rectirostris, 101.

vetula, 95.
Daphnella, 14, 89, 109.

Wiugii, 109.
Daphnia, 14, 62, 88, 89, 103, 105, 106.

angulosa, 98.

Mspinosa, 99.

brachiata, 102.

crystallina, 107.

curviroslris, 103.

cornuta, 105.

congener, 96.

ephippiata, 90.

eu'spiuosa, 96.

lougispiua, 91.

macrocopus, 101.

magna, 91.

media, 90.

mucronata, 98.

mucronata, 99.

pennata, 90.

psittacea, 92.

pulex, 89.

pulex, 93.

quadrangula, 97, 98.

ramosa, 90.

rectirostris, 101.

reticulata, 97.

reticulata, 98.

rosm, 104.

rotunda, 98.

Schosfferi, 93.

«wtf, 95.

ventricosa, 97.

352

INDEX.

Daphnia vetula, 95.
Daphniadse, 14.
Daphnina, 88, 89.
Daphnidtf, 115.
Daphnides, 62, 115.
Daphnidiens, 62, 115.
Daplinoides, 62.
Der Satyr, 205.
Diaptomida?, 14, 218.
Diaptomus, 14, 218, 219.

Castor, 219.
Dichelestidts, 290.
Dinematura, 282.

alata, 285.
Dinemoura, 15, 281, 282.

alata, 285.

lamnse, 286.
Dinemura, 282.
Disptonms Castor, 220.
Doris min itt a, 205.

Entomoda, 327,

cornuta, 328.

salmonea, 335.
Entomostraca, 14, 16.
Ergasilidse, 15, 299.
Ergasiiiens, 299.
Erffasilina, 296.
Eunica, 105.

longirostris, 105.
Eurycercus, 14, 123.

lainellatus, 124.
Evadne, 14, 114.

Nordmanni, 114.
Eye of the Greenland Shark, 333.
Eye-sucker, 341.

Fisch-laus, 256.

Floss-fussigen seewurm, 30.

Four-horned Cyclops, or small Water-
flea, 199.

Gammarus, 54.

salinus, 61.

Geschicanzten zackiger Wasserfloh, 93.

Glaucea carulea, 220.
rubens, 220.

Harpacticus, 204.
Horned Lerntea, 328.

/wo, 39.

piscina, 54.
Ireneeus, 229.

splendidus, 229.

Kiefenfuss, 30.

Laxe-luus, 274.
Lsemargus, 15, 293.

muricatus, 295.
Ze Monocle a quatre cornes, 199.

a queue four chue, 198.

« ywe?^ retrowsee, 112.
Ze Perroquet d'ean, 90.
Ze Pweeron verdatre, 91 .
Lepeoptheirus, 15, 268, 273.

hippoglossi, 276.

Nordmaimii, 275.

obscurus, 277.

pectoralis, 275.

Stromii, 274.

Thompsoui, 278.
Lernacantha, 326.

Delarochiana, 327.
Zeni^a, 327, 329, 332, 336,
339, 342, 344.

asellhia, 329.

cauda duplici tereti, 329.

cornuta, 328.

cyclophora, 341.

cyprinacea, 343.

elongata, 333.

encrasicoli, 341.

fjadina, 345.

pectoralis, 275.

salmonea, 335.

spratta, 341.

uncinata, 337,
Lernea, 15, 344.

branchialis, 344.
Lerneadse, 15, 307.
Lerneide articulee, 341.
Lerueutoma, 15, 327.

asellina, 329.

cornuta, 328.

Lophii, 330.

^>/^, 329.
Lerneocera, 15, 339, 342, 344.

branchialis, 345.

cyprinacea, 343.
Lerneoceradge, 15, 342.
Lerneocenens, 338, 339, 342.
Lerneomyzon, 336.

•uncinata, 337.
Lerueonema, 15, 339.

encrasicoli, 341.

monillaris, 341.

spratta, 341.
Lerneopenna, 339.

INDEX.

353

Lerneopoda, 15, 332.

carpionis, 335.

elongata, 333.

galei, 334.

salmonea, 335.
Lerneopodadse, 15, 332.
Lerneopodiens, 331, 332, 336.
Les Monocles, 16.
Limulus, 29.

cancriformis, 30.

palustris, 30.
LopJiyropa, 138.
Lophyropoda, 14, 138.
Louse of the bansticJcle, 256.

carp, 256.
Lynceidse, 14, 115.
Jjynceus, 103, 105, 115, 123, 125,
128, 129,131,134,136.

hamatus, 136.

harpa>, 129.

lamellatus, 124.

laticornis, 103.

leucocephalus, 129.

longirostris, 105.

macrourus, 128.

quadrangularis, 131.

roseus, 104.

sp/ieeric?(s, 126.

trigonellus, 134.

truncatus, 137.

Macrothrix, 14, 88, 103.

laticornis, 103.

roseus, 104.

Marteau d'eau douce, 54.
Moina, 14, 88, 100.

bracbiata, 102.

rectirostris, 101.
Monocles a coquille bivalve, 151.
Monoculits, 16, 17, 29, 30, 36, 89,
103, 105, 106, 111, 151,
183, 198, 204, 212, 219,
227, 242, 269.

apus, 30, 198.

argulus, 255.

lispinosus, 99.

bistrigatics, 157-

brachiatus, 102.

cteruleus, 219.

castor, 219.

cauda biseta, 30.

caudafoliaceaplana, 256.

cMy%r, 212.

conchacens, 96.

Monoculus cornntus, 105.

crystallinus, 307.

cyprinaceus, 256.

delphimis, 255.

detectus, 161.

elongatiis, 107.

exspinosm, 96.

Finmarchicus, 228.
flavidus, 168.
foliaceus, 255.

ffyrini, 255.

infusorius, 126.

lacimdatus, 220.

&m's, 96.

lamellatus, 124.

laticornis, 103.

longicornis, 228.

longispinus, 91.

macrourus, 128.

?« iimticornis, 211.

minutus, 205.

monachus, 153.

mucronatus, 99.

nasutus, 96.

oculus, 112.

<?#«#?, 155.

pediculus, 111.

pediculus ramosus, 111.

folyphemus, 112.

js«fer, 89, 96.

yulex arboresccns, 90.

pulex ramosits, 90.

quadrangularis, 97, 131.

quadrangulus, 131.

quadricornis, 198.

rectirostris, 101.

reticulatus, 97.

roseus, 104.

restrains, 96.

rubens, 220.

sinms, 96.

spfuericus, 126.

staphylinm, 205.

striatus, 131.

strlgatus, 157.

trigonellus, 134.

truncatus, 137.

viduatus, 152.

viduus, 152.
My sis, 36.

Nauplius, 204, 212.
e/fe/j/fcr, 212.
-furcatus, 210.

23

354

INDEX.

Naupliws minutits, 205.

saltatorivs, 199.

Stromii, 208.
Nebalia, 14, 31, 36.

bipes, 36.

ciliata, 36.

qlabra, 36.

Herbstii, 36.

Montagui, 36.
Nebaliadse, 14, 31.
Nicothoe, 15, 300.

astaci, 307.
Nicotliaidee,, 299.
Notodelphys, 14, 237.

ascidicola, 238.
Omethia, 219.
Oniscus, 269.
Ostracins, 138.
Ostracoda, 14, 138.
Ostracodes, 138.
Ostrapoda, 138.
Otrophesa, 296.

imbricata, 299.
0«o/*«, 242.

gasterostei, 256.

Pachycephala, 15, 295.
Pandaridge, 15, 281.
Pandariens, 281, 289.
Pandannae, 281.
Pandoras, 15, 281, 282, 286.

0to#s, 285.

bicolor, 288.

Boscii, 289.

lamntp, 286.
Parasite/, 240.
Pasithea, 101.

gibba, 101.

rectirostris, 101.
Pectoral Lernaia, 275.
Pediculus, 269.

aquations, 199.

salmonis, 335.
Peltocephala, 15, 241.
Penelladte, 15, 339.
Peracantha, 14, 123, 136.

truncata, 137.
Pe^V insecte aqitatique, 256.
Phylkpa, 17.
Phyllopoda, 14, 17, 18.

Pleuroxus, 14, 123, 134.

hamatus, 136.

trigonellus, 134.

uncinatus, 135.
Pnemnonura, 240.
Psecilopoda, 15, 240.
Polyphemidse, 14, 111.
Polyphemus, 14, 111.

oculus, 111.

pediculus, 111, 112.

stagnorum, 112.
Pow^'a, 229.

Patersonii, 229.
Pontiadee, 233.
Pontieiis, 233.
Pow aquatique, 90.
Ps&udopoda, 183.
Puceron branchu, 90.
r arborescens, 90.

Remarkable aquatic insect, 54.

-, 199.
Scalicerus, 112.

pediculus, 112.
Schisturus uncinatus, 337.
Scolopendra aquatica scutata, 30.
See-laus vom Hemorfisch, 286.
Sida, 14, 89, 100.

crystallina, 107.
Sidina, 89, 106.
Siphonostoma, 15, 16, 240.
Small Cyclops, or Vaulter, 205.
Smooth white insect, 161.
Sguilla lacustris minima, 54.

Temora, 14, 218, 227.

Finmarchica, 228.
Thecata, 240.
Trebius, 15, 268, 280.

caudatus, 280.
TWopw, 29.

palustris, 30.
Triops cancriformis, 30.

Ungescliwanzter-zacTciger JFasserfloh,

96.
Vermes minimi nibri, 90.

Wetter-flea with branched horns, 90.

EXPLANATION OF PLATES.

TAB. I.
F'ig. 1. Apus cancriformis .

a. Mandible, b. Mouth. c. Aiitenua. d. First pair of feet.
e. Second do. /. Eleventh do. cj. Twelfth do. h. Branchial plate.

2. Young animal. 3. Do. a little older.

TAB. H.
Fig. 1. Nebalia bipes.

a. First pair of jaws. b. One of the branchial feet. c. One of the
natatory feet.

2, 3. Artcmia salina, male and female.

Fig. 2, a. Antenna of male. b. Antennulc. c. One of the branchial feet.

4. Do. young.

TAB. III.

Figs. 1,2. Cfiirocephalus diaphanus, male and female.

TAB. IV.
C/tir o ceph alus diap h an us .

Fig. A. Autennule. B. Prehensile antennae of male. c. Appendages
belonging to them. c*. Profile view of ditto. D. Triangular plate
of ditto. E. Head of female in profile, with antenna;. F. Dorsal
view of ditto, to show the eyes. G. Labrum. H. Mandible.

In Figs. B, c, c*, E, and F — a, represents the autenuules ; b, large

antennae ; c, trunk ; d, flexible appendages ; e, triangular plate ;

f, organ similar to what is seen in Evadue ; y, eyes ; h, remains

of foetal eye ; i, organ similar to what Zaddacu calls in Apus

the glandular processes of stomach ; /-, mandible ; m, labrum.

TAB. V.
Chirocephalus diaphanus.

Fig. A. Jaws. * One of the setae magnified. B. One of the branchial
feet. c. Male organ of generation.

Fig. 1. Ovum.

2. Young, half detached from ovum.

3. Young, while still in internal envelope.

4. Do. two hours old.

5. Do. a little further advanced.

(5. Do. in a more advanced stage of development.
7. Do. still further advanced.

350 EXPLANATION OF PLATES.

TAB. VI.

Figs. 1, 2, 3. Daphnia pidex ; male and female, and
variety.

TAB. VII.

Fig. 1. Daphnia Schcefferi, female.

2. Do. young.

3. Daphnia pule(c ; variety Icmgispina.

4. Do. young.

5. Daphnia reticnlata, female.

TAB. VIII.

Daphnia Schcefferi, details.

Fig. A. Head, principally to show the muscular system, a, u. Basal
joint of large antenna, with its elevator and depressor muscles.
b. Aiiteunules. c. Eye, with its rotatory muscles, optic nerve,
and brain, e, k. Muscles attaching the body of the animal to the
carapace, f. Mandible, with its muscles, y. Muscle of the
labrum. p. Jaws.

Fig. B. Head, principally to show the organs of digestion, b, c,f,p,
represent the same organs as in fig. A. d. Caecum, e. Stomach.
y. Labrum. i. Heart.

Fig. c. Labrum, with a, b, c, its elevator and depressor muscles.
D. Mandible. E. One of the first pair of legs. F. Second do.
<;. Third do. H. Fourth do. I. Fifth do. p. Jaws.

TAB. IX.

Fig. 1. Moina brachiata. Fig. 4. D. psittacea, young.

2. Do. young. 5. D.pulex, young.

3. Daphnia psittacea, 6. D. rotunda, young.

TAB. X.
Fig. 1. Daphnia vetula.

a. Head magnified to show anteunules.

2. D. mucronata; var. obtuse rostrata.

3. D. mucronata; var. acute rostrata.

4. D. rotunda.

((. Head magnified to show anlennules.

EXPLANATION OF PLATES. 357

TAB. XI.

Figs. 1, 2. Moina rectirostris, male and female.

1 a. Autennule of male

3. Daphnia pulex ; var. mayna, female.

4, 5. Male of do.

Fig. 4 represents the male in a very young state, previous to its

final moulting, and before it assumes its perfect form.
5 a. Antennule of male.

TAB. XII.

Fig. 1. Daphnia reticulata, male.

a. Antennule. b. One of the first pair of feet.

2. D. reticulata ; var. quadrangula.

3. Sida cri/stallina, female.

Fig. A. Head magnified, in profile, b. Antennule c. Eye.
e. Stomach, f. Mandible, g. Labrum. q. Organs by
which the animal attaches itself to objects, r. Heart.

Fig. B. Eye magnified, to show the disposition of the crystallines
or facets.

4. Sida cri/stattina, young.

TAB. XIII.
Fig. 1. Sida crystallina.

a. Antennule. b. Large antenna or ram us. c. Mandible. </. One
of the first pair of feet, e, f. Fourth pair of feet. tj. Sixth
pair of feet. h. Abdomen.

TAB. XIV.

Fig. 1. Daphnella Winyii, female.

3. Do. supine.

4. Head of do. highly magnified.

a. Stomach, b. Antennule. c. Eye. f. Mandible, y. Labruiu.
•/. Heart, o. (Esophagus.

'2. D. iringii, male.

a. Autennule. b. Abdomen.

358 EXPLANATION OF PLATES.

TAB. XV.

Fig. 1. Eurycercw lamellatus.

a. Superior auteuua. I. Inferior do. c. Mandible, d. Labrum.
d*. Jaws. e. First pair of feet. / Second do. (/. Third
do. h. Fourth do. i. Fifth do. k. Abdomen. I. Eye.

2. Macrothrix laticornis, female.

a. Inferior antenna.

3. Bosmina longirostris.

a. Inferior antenna.

TAB. XVI.

Fig. 1. Peracantha truncata.

a. Inferior antenna, b. Intestine.

2. Alona ovata. Fig. 3. Alona reticulata.

4. Alona quadrangularis.

a. Labrum. b. Abdomen.

5. Acropems harp a. Fig. 6. Acropenis names.

1 . Cliijdorus globosus.

a. Jaws. b. Inferior antenna, c. Abdomen.

N. Cliijdorus spharicus.

9. Cawptocercus macrourus.

(i. Abdomen.

TAB. XVII.
Fig. 1. Polyphemus pediculns.

ft. Inferior antenna, b. One of the first pair of legs.

2. Evadne Nordmanni.

a. View of the legs (frornLoveu).

3. Pleuroxus trigonellus.

a. Auteunule. b. First pair of feet. c. Abdomen.

4. P. uncinatus. Fig. 5. P. hamatua.

Fi.H1. A. Convoluted intestine of Euryccrcus lamellatus.
Fig. K. Do. of Chydoms globosus.

it. (Esophagus, b, c, d. Convolutions. _/. Anus.

EXPLANATION OF PLATES. 359

TAB. XVIII.

Fig. 1. Cypris tristriata.

o tj-i-

a. Body of the animal, with the shell removed. b. Superior
antenna. c. Inferior do. d. Mandible, e. First pair of
jaws. e*. Branchial plate of do. f. Second pair of jaws.
g. First pair of feet. h. Second pair of do. i. Abdomen.

2. Ovum. Fig. 5. C. Joanna.

3. Young. 6. C. monacha.

4. Cypris clavata. 7, 8. C. minuta.

TAB. XIX.

Fig. 1. Candona lucens. Fig. 7. C.fusca.

2. C. simttis. 8. C. gibbosa.

a. Inferior antenna. 9. C.

3. C. reptans. 10, 11. C. vidua.

a. Inferior antenna. ^2. C. elliptic a.

4. C. hispida. 13. C. aurantia.

5. Cypris sella. 14. C. comprcssa.

^ a. Inferior antenna. (( guperior antenua b In_

6. (7. elongata. ferior do. c. Mandible.

TAB. XX.

Pig. 1. Cythereis Jonesii. Fig. 3, 3 «. (7. Wkiteii.
2. (7. antiquata. 4. Cy there Minna.

4«. Mandible and palpus, i. Superior antenna, e. Inferior do.
^. First pair of legs.

5. Cy there reniformis.

a. Body of animal, with the shell removed, b. Superior antenna.
c. Mandible and palpus, d. First pair of jaws, with the
branchial plate attached, e. Inferior antenna, f. Last pair
of feet.

6. Cy there alba. Fig. 7. C. albo-maculata.

360 EXPLANATION OF PLATES.

TAB. XXI.
Fig. 1 . Cythere inopmata.

a. Ventral view. b. Superior antenna, c. Inferior do. d. First
pair of legs. e. Last pair of do.

2. C. quadridentata. Fig. 8. C. aurantia.

3. C. convexa. 9. C. impressa.

4, 4«. C. nigrescens. 10, 100,11. C. varin-

5, 5 a. C. acuta. bilis.

6, 6«. C, angmtata. 12, 1'2 a. C.favida.

7. C. peUucida.

TAB. XXII.

Fig. 1 . Cypridina Mac Andrei.

a. Animal, with the shell removed. /;. Natatory feet. c. Second
pair of antennae, d, d. Second pair of jaws. e. First pair of
antennae, f. Oviferous foot. g. Abdomen.

TAB. XXIII.
Fig. 1 . Cypridina Brenda.

n. Eye. b. Natatory foot. c,c. Second pair of antennae, d. Second
pair of jaws. e. First pair of antennae. /. Oviferous foot.
g. Branchial plate of first pair of jaws.

TAB. XXIV.

Cyclops quadricornis.
Fig. 1. Male. Fig. 6. Ovum.

2. Female. 7. Young, just born.

3. Var. «, elongatus. 8. Do. 8 days old.

4. Var. b. 9. Do. 15 days old.

5. Var. c. 10. Do. 17 days old.

a. Anteuuule. b. Mandible, c. First pair of foot-jaws, d, e. Se-
cond pair of foot-jaws, (d. Internal division, e. External
do.) /. First pair of thoracic feet. g. Fifth pair of feet ;
fulcra, or "supports."

EXPLANATION OF PLATES. 361

TAB. XXV.

Tigs. 1, 2. Canthocamptm furcatns, prone and in profile.

2 a, First pair of thoracic feet.

3. C. minuticornis.

4, 5. C. mi mdus, male and female.

4#. Antenna of male. 5 a. Do. of female, b. Anteimule.
c. Mandible, d. Second pair of foot-jaws, e. First pair of
do. f. First pair of thoracic feet. y. Second pair of do.
//. Third pair of do. i. Fifth pair of feet.

TAB. XXVI.
Figs. 1, 2. Diaptomus castor, male and female.

2 a. Anteunule. b. Mandible, c, d. First pair of foot-jaws.
(d. Profile view.) e. Second pair of foot-jaws, f. Third
pair of do. y. First pair of thoracic feet. //. Second pair of
do. i. Fifth pair of feet, in the male. j. Do., in the female.

TAB. XXVII.
Figs. 1, 2. Anomalocera Patersonii, male and female.

1 a. Antennule. b. Mandible and palpus, c. First pair of

foot-jaws, d. Second pair of foot-jaws, e. Third pair of
do. /, g. The head in two different positions, to show the
sharp-pointed beak, and the situation of the eye. Ji. First
pair of thoracic feet. i. Fifth pair of feet in the male.

2 a, b. Head of female ; two different views to show the beak, the

eye, and the sharp, curved spine on first ring of thorax.
c. Fifth pair of feet in the female.

3. Canthocamptus Stromii.

a. First pair of thoracic feet.

TAB. XXVIII.

Fig. 1. Temora Finmarchica.

a. Mandible and palpiform branch, b. Antennule. c. First pair
of foot-jaws, d. Second do. e. Third do. /. Antenna.
g. First pair of thoracic feet.

2. Arpacticus nobilis.

a. Antenna, b. Antennule. c. Fifth pair of feet. d. Posterior
foot-jaws, e. First pair of thoracic feet.

24

362 EXPLANATION OF PLATES.

TAB. XXIX.

Fig. 1. Cetochilus septentrionalis.

a. Styliform appendages in front of cephalo-tkoraeic segment,
which take the place of the sharp-pointed beak of Anoinalocera.
b. Mandible and palpus, c. Antennule. d. First pair of
foot-jaws, e. Second do. f. Third do. g. First pair of
thoracic feet.

2, 3. Arpacticus chelifer, male and female.

3 a. Antenna. 1. Anteunule. c. Mandible, d. Fifth pair of feet.
e. Posterior foot-jaws. /. First pair of thoracic feet. g. Se-
cond pair do.

TAB. XXX.

Figs. 1,2. Alteutha depressa, male and female.

a. First pair of thoracic feet. b. Abdominal appendage.

3. Cantliocamptus minutus, to show the club-shaped
organ attached to the abdomen.

4, 5, 6. Cantliocamptus fur catus.

4 a. Ovary.

5 a. Antennule. b. Last pair of feet.

These figures are copied from drawings made by Mr. Salter.

7, 8. Notodelpliys ascidicola.

7 a. Antennule (?). b. Mandible, c. First pair of foot-jaws, d. Se-
cond do. e. Third do. / Fourth do. g. One of the natatory
feet.

TAB. XXXI.

Fig. 1. Argulus foliaceus.

2. View of part of the carapace, to show the ramifi-
cation of opaque tubes or intestines.

a. Antenna, b. First pair of foot-jaws, d. Sheath containing
the siphonal tube, c. Extremity of siphon, with its sharp-
pointed style. e,f. Second pair of foot-jaws, or ^suckers,
g. Third pair of foot-jaws, or prehensile feet. //, i. First pair
of natatory legs, k, I. Fourth pair of do.

EXPLANATION OF PLATES. 363

TAB. XXXII.

Fig. 1. Caligus diaphanus.

2, 3. C. rapax, male and female.

4, 5. C, Mutteri, male and female.

6, 7. C. centrodonti, male and female.

8, 9. Lepeoptheirus Stromii, male and female.

10. L. pectorcdis, female.

11. L. obscurus*

12. L. liippoglossi, female.

TAB. XXXIII.

Fig. 1. LepeoptJieirus Nordmannii.

2. L. Thompsoni.

3, 4. Trebius caudatus, male and female.

5, Chalimus scombri.

a. View of do., adhering to Caligus Mullen, b. Eostrum.

6, 7. Dinemoura alata, male and female.

8. D. lamnce, female.

9. Anthosoma Smithii.

10. Pandams bicolor, female.

11. Nicotkoe astaci.

TAB. XXXIV.

Figs. 1,2. Cecrops Latreilleii, male and female.
3, 4. Lcemargus muricatus.

5. Carapace of Caligus diaphanus ; under surface,
to show the different organs in situ.

a. Lunules or sucking-discs, b. Antenna, c. First pair of foot-
jaws, f. Mouth, g. Organs representing the posterior pair
of jaws. h. Second pair of foot-jaws, i. Third pair of do.
j. Sternal fork. k. First pair of thoracic feet. /. Second
pair of do. m. Third pair of feet. n. Fourth pair of do.

Fig. A. First pair of foot-jaws of Lepeoptheirus Nordmannii. B. Mouth
and posterior jaws of do. c. Sternal fork of do. D. Sternal
fork of L. hippoglossi. E. Fourth pair of feet of Trebius
caudatus.

* This may possibly prove to be the male of L. hippoylossi.

304 EXPLANATION OF PLATES.

TAB. XXXV.

Fig. 1. Chondr acanthus Zei.

2. Lernentoma cornuta.

3. L. JjOjj/iii.

4. L. asellina.

5. Lerneopoda elongata.

6. L. salmon ea.
1. L. galei.

8. Anchor ella rugosa.

9. A. uncinata.

10. Lerneonema spratta.

11. Z. encrasicoli.

12. Lernea branchidlis.

13. Lerneocera cyprinacea.

TAB. XXXVI.

Figs. 1, 2,3. Ovum and young, in different stages, of a
Caligus.

Taken from figures by H. Goodsir in ' Edinb. New Philo-
sophical Journal,' vol. xxxiii, tab. 3.

4, 5. Profile and under-side view of the male of
Anchorella imcinata.

6, 7. Male of Lernentoma cornuta, profile and under-
side.

These two species are taken from figures by Nordmanu,
' Mikr. Beitr.' tab. ix and x.

8. Young of a species closely allied to Lerneocera

cyprinacea.

Prom Nordmann, 1. c. tab. vi.

9. Male of Lerneopoda clongata.

Taken from Kroyer's ' Tidsskrift,' vol. i, tab. iii.

10. Male of Lernentoma Lophii.

Prom Kroyer, 1. c.

11. M.si\eofl>erneopoclafjfalei.

Prom Kroyer, 1. c.

Pig. A. Under surface of head of Anclwrella uncinata, magnified.
a, b. Organs of mouth. c. Styliform appendage to do.
d. Antenna. e,f,(/,h. Poot 'aws.

Prom Nordmauu, 1. c. tab. viii.

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Reeve Beivham &. "Ree-^e,

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5. CYPR1S SELLA 10.11. C.VIDUA.

6. C. ELOlTCiATA. 12 C.ELLIPTICA.
1 C i ' 'A. 13. C AURANT1A.

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4 C. NIGHESCETSTS. 8 C AURANTIA

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Tab .XXVII.

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1—2. ANOMAL 0 CER.A T A T E R S 0 1ST II .
3. CANTHO CAMPTUS STUOMIi.

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Tat. XXIX.

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1. CETOCHILUB SEP TENTRIO^ALI S .
2. AB.PACTIUU8 CHELIFEB .

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4.5.6. C .BURCATUS .

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lab XXXII.

Id1 GALICUS D1APHANUS

39 C.RAPAX.

5 9 C MULLERI

7? C.CENTRODONTl.

^9$ LEPEOPTHEIRUS STB.OMII.
10$ L PECTORALie
11? L OBSCURITS
12 ¥ L HIPPOGLOSSI.

ing.

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Tab. XXXIII.

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19 LEPEOPTHEIRUS NOHDMANKII.
2? L. THOMPSONI
^4? TTIEBITJS CAUDATUS.
5rf CHA.LIMUS SCOMBRI .

69PANDARUS Bl COLOR,
7 ? DINEMOURA LATvlNJE
i.9.9 D ALATA

10? ATsTTHO SOMA SMITHII
11?. TSTICOTHOE ASTAC1

3.

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l.d-2.9 CECROPS LATREILLEII. A.B.C. LEPE OP THEIRUS NORDMAKNI.

3 4.s L&MARCUS MURICATUS + 3). L HIPPOCLO S SI .

+ 5 ¥ CALIG-US DLAPHANUS + E. TREBIUS CAUDATUS.

"W Wiivg alna.tlith B.eeve BenKam fc Reeve.ojr

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10.

11

: CHO]\IDRACANTHUS ZEI 5 LERTTE OPODA EL01TGATA 10. LEB.NEONEMA

2. LERNENTOKA. CORWUTA 6. L SALMONEA SPRATTA

3. L . LOPH1I 7. L GALEI 11. L.ENCRASIGOLI .

4 L ASELLINA 8. ANCHOE.ELLA RUGOSA 12 . LEKNEABTLANCHIALIS.

9 A UNCINATA 13.LEKNEOCEB.A CYPRINACBA.

• D XXXVI

A

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:GUS JUWs 9. LERNEOPODA ELOWCIA^'A <t

' 5 AKCHORELI,/ i \. ; IN ATA cf. 10 LERNE14 TOMA LOPHII d1

6. 7 LEU-REN TO MA CO] . , A .a. 11. LERN.EOPODA G-ALEI .

OCEHA-JUNi A ANCHORELLA i ' bTATA

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