# Library of the University of Toronto •r*yiriA-{ S-r-C 'fy-tr C > jf*£T ' RAY SOCIETY. INSTITUTED MDCCCXLIV. LONDON. MDCCCL, THE NATURAL HISTORY OF THE BRITISH ENTOMOSTRACA. BY W. BAIRD, M.D. F.L.S. ETC. LONDON : PRINTED FOR THE RAY SOCIETY. MDCCCL. “ NiMl enim, quod ad Dei immensam gloriam augendum, et ad Naturae miracula aperiuuda faciat, reconditum et absconditum domesticis lustrationibus sepelire debemus.”—- Schceeeer, Apus Pisciformis, 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 — Summer. C. AND J. ADLARD, PRINTERS, BARTHOLOMEW CLOSE. PEEEACE. 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 Homo- 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 Lerneadae 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 v: PREFACE. in bearing testimony, and to whom iny 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. Bayswater ; December 1849. TABLE OF CONTENTS. Introduction Systematic Arrangement Tabular View of Arrangement PAGE . 1 . 9 . 14 Entomostraca , Synonyms and Character Branchiopoda „ „ Phyttopoda ,, „ Apodidce, Bibliographical History „ Anatomy and Physiology Nebaliadae, Bibliographical History „ Anatomy and Physiology Branchipodidce, Synonyms and Character Chirocephalus, Bibliographical History „ Anatomy and Physiology Artemia , Bibliographical History . „ Anatomy and Physiology Cladocera, Synonyms and Character Daphniadte, Bibliographical History „ Anatomy and Physiology Polypliemidce , Synonyms and Character Lynceidae, Bibliographical History „ Anatomy and Physiology Lophyropoda, Synonyms and Character Ostracoda „ >, Cyprididce , Bibliographical History ,, Anatomy and Physiology Cytheridce, Synonyms and Character Cy there, Bibliographical History „ Anatomy and Physiology Cypridinadee, Character Copepoda, Synonyms and Character Cyclopidce , Bibliographical History „ Anatomy and Physiology Diaptomida, Character Cetochilidce, Synonyms and Character . Pcecilopoda „ „ . 16 . 17 . ib. . 18 . 20 . 31 . 33 . 38 . 39 . 42 . 55 . 57 . 62 . ib. . 69 . Ill . 115 . 117 . 138 . ib. . 139 . 143 . 162 . 163 . 164 . 176 . 182 . 183 . 186 . 218 . 233 . 240 vill CONTENTS. PAGE Siphonostoma, Synonyms and Character . . . 240 Peltocephala, Character . . . . 241 Argulidae, Bibliographical History .... 242 „ Anatomy and Physiology . . . 246 Caligida , Bibliographical History . . . .257 ,, Anatomy and Physiology . . . 260 Pandaridce , Synonyms and Character . . . .281 Dinemoura, Bibliographical History . . . .282 „ Anatomy . . . . .283 Pandarus, Bibliographical History . . . .286 „ Anatomy ..... 287 Cecropida , Synonyms and Character . . . .289 Cecrops, Bibliographical History . . . . ib. „ Anatomy and Physiology . . . 290 Lcemargus , Bibliographical History . . . .293 „ Anatomy, &c. . . . . 294 Pachycephala , Character . . . . .295 Anthosomada, Synonyms and Character . . . . 296 Anthosoma, Bibliographical History . . . . ib. „ Anatomy and Physiology . . . . 297 Ergasilidae, Synonyms and Character .... 299 Nicothoe, Bibliographical History . . . 300 „ Anatomy and Physiology .... 301 Lerneada, Bibliographical History and Systematic Arrangement . . 307 „ Anatomy and Physiology . . . .316 Anchor astomacea, Character . . . . . 323 Chondracanthida , Bibliographical History . . . ib. „ Anatomy, &c. . . . . . 324 Anchoracarpacea, Character . . . . .331 Lerneopodidte , Character, &c. . . . . 332 Anchor ellada. Character . . . . .336 Anchorella , Character, &c. . . . . ib. Anchoraceracea , Character . . . . .338 Penelladce, Character . . . . . 339 Lerneonema, History . . . . . ib. Lerneoceradce, Character . . . . 342 Lerneocera, Character, &c. . . . . ib. Lernea „ . . . . 344 Appendix . . . . . . 346 Index ...... 349 Description of Plates . . . . 355 Erratum.— For Cypridse read Cyprididfe, p. 139 et passim. NATURAL HISTORY OP THE BRITISH ENTOMOSTRACA. INTRODUCTION. In this monograph I have retained the name Entomo- straca, using it to comprehend all those minute Crustaceans described by Muller 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, 1 2 BRITISH ENTOMOSTRACA. that a person ignorant of the inhabitants would 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 Muller the name of Entomostracon , a term derived from two Greek words signifying “an insect with a shell.” * Previous to the appearance of Muller’s work, the few 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. Schoeffer proposed the name Branchvpodes for them, from their feet possessing branchial appendages; and Muller says he would have pre- ferred this name to that of Monoculus, were it not that several genera wanted these organs. The genera, however, which he mentions, are the Nauplius and Amymone, and the Gythere. 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 JEntomosiraca ; 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, Redi, Leeuwenhoek, Trembley, Baker, Frisch, and J oblot 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 Geoffroy, Strom, Goeze, Herbst, and De Geer soon afterwards added to the number. It is to the celebrated Danish naturalist, Otho Fredericus Muller, however, that we are most indebted. To him we owe the collecting the various species already made known into one * Miiller, Entomost., p. 2. 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 waiters, is still one of the most interesting memoirs in natural history that we are acquainted with. Since the time of Muller 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 Muller, 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 * Entomostraca, seu insecta testacea, quse in aquis Daniae et Norvegise reperit, descripsit, et Iconibus illustravit Otho Ereaericus Miiller. Lipsiae et Havnise, 1785. 4 BRITISH ENTOMOSTRACA. 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 Fulex aquaticus ? 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 Muller 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 Muller 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 the common opinion that it is the Caligi which force the salmon from the sea, up rivers towards the waterfalls.” INTRODUCTION. 5 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 Muller and Straus, the greater number of the Entomostraca, not parasitical, live upon vegetable matter, and not upon animals ; and the former, in an experiment he instituted, says,t that in keeping a number of species, such as the Baphnia pennata and longispina , Cypris strigcita and pilosa , Lynceus sphericus and Cyclops quadricornis , in the same water from the 24th of July to the 2 2d 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. f 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. Jurine asserts that the Cyclops quadricornis is carnivorous from taste, and only herbivorous from necessity ; while the Daphnia pulex, he distinctly affirms, lives upon ani- malcules. Place a few Entomostraca, such, for example, as theDaphnise, 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 their dead bodies, we see 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, which no doubt serve their purposes also in the economy of nature. The fresh-water Gammari seem to prey upon them, and the Hydrachnse are their decided enemies ; INTRODUCTION. 7 “ for,” says Muller, “ they seize hold of them while swimming, by their feet, and daintily suck the life’s blood out of then’ captives with their sharp beaks.”* * * § “ The Hydreef also, and not a few aquatic larvae, lay snares for them, and many Vorticellae 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.”J The larva of the Corethra plwnicornis , known to microscopical observers as the skeleton larva , is exceedingly rapacious, more especially of the Daphniae. 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 Lurco , and which de- vours them in great numbers. || The Chydorus sphericus 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 glutton. Those in the first and second stomachs were still ali ve, while those contained in the in- * Entomost. p. 8. f “It would appear that there is something eminently poisonous to animals in the fresh- water Hydrse. ‘I have sometimes,’ says Baker, f 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 and Daphnise, entangled in the tentacula 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. % Loc. cit., p. 8. They are frequently covered completely with a small polype, called by M. Ileamur “Polypes a boucjuet;” for an account of which see Trembley’s ‘ Memoire sur l'es Polypes a bouquet, a la suite des decouvertes de Needham,’ 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 1747, previously to Mr. Trembley’s work being published. § Brightwell, Zool. Journ., v, 396 ; and t. xix, f. 1. || Microscop. Cabinet, p. 81. 8 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 Heroes. “ The fact of Beroes feeding upon small Crustacea,” says Mr. Paterson, “ has been recorded by Pabricius, and at present appears to rest upon his authority. It was interesting to observe the fad , 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 tlieir 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 Daphnise and Cyclops, &c. * Letter from Mr. Paterson to Mr. Templeton, in the Memoir on Ano- malocera, in Trans. Ent. Soc., ii, part 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. Linnaeus 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 vm, Polygonata, and the genus Limulus in the ixth, Kleistognatha.f Muller, following his predecessors in arranging the Crustacea amongst the Insecta, places of course the Ento- mostraca in that class also.J 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^ and Cuvier, || in their first published Methods, also placed the Crustacea amongst the Insecta, the former adopting the arrangement of Muller with regard to the Entomostraca, and dividing them into two families, the * Consid. gen. sur les Crustaces, 1825. f Systema Entomologise, 1775 ; Entomologia Systematica, 1793. X Entomostraca, 1785. § Precis des Caracteres gen. des Insectes, 1796. || Tableau element, de l’Hist. Nat. des Animaux, 1798. 10 BRITISH ENTOMOSTRACA. Monoculi and Binoculi. Brisson, however, in his ‘ Regne Animal/ * as early as 1756, 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. He forms four orders : 1st, Paecilopoda, 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 antennae, terminated by long- setae, and the others formed for swimming ; 3d, Lophy- ropoda ; and, 4th, Branchiopoda, in which all the feet are formed for swimming. * Lc Iteg’nc Animal, divis. cn 9 Classes, &c. SYSTEMATIC ARRANGEMENT. 11 Lamarck, in his e 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 Mtlller’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, Paecilopoda, 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 Paecilopoda, on the other hand, is composed of rather heterogeneous materials, and is divided into two families, the Xiphosura and Siphonostoma.* * Latreille appears to have been struck with the resemblance which the Lernese 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 Lernese undergo a metamorphosis like that of the Cyclopidse and Caligidse, and that 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 between them and the Entomostraca. 12 BRITISH ENT0M0STRACA. M. Milne Edwards, in his excellent work on the Crus- tacea,* adopts the organization of the mouth as the basis of his arrangement also. He divides the great class Crustacea into three sub-classes. 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 Sugeurs, or those whose mouth is furnished with an apparatus for sucking ; and the third is that of the Xyphosuriens, 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- mapodes; 2d, Edriophthalmes, containing the orders Amphipodes, Isopodes, and Lsemipodes ; 3d, Branchio- podes, containing the orders Cladoceres and Phyllopodes; and, 4th, Entomostraces, containing the orders Ostrapodes and Copepodes. In this arrangement, the last twro 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 Sugeurs, he divides into two legions, the Parasites nageurs, containing the orders Siphonostomes and Ler- neens ; and the Parasites marcheurs, containing the order Araneiformes. The last sub-class, the Xyphosuriens, con- tains the single order Xyphosures. In this method we see the Lernese constitute a portion of Latreille’s Peecilo- poda, into which they were refused admittance by him. They were placed by Cuvier, in his ‘ Regne Animal/ amongst the Zoophyta, and in general, till within a few years, they were classed by naturalists amongst the Vermes. Desmarest showed the relations they had with * Hist. Nat. des Crustaces ; suites a Buffon, 1834-40. 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 Cyclopidae, und 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 wrhich formerly wTere 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 Annulosa, in the Synopsis of the British Museum, 1842. The following table will give a connected view of the arrangement of the British Entomostraca which I propose to adopt. 14 BRITISH ENTOMOSTRACA. Sub-Kingdom ANNULOSA. Class CRUSTACEA— Division ENTOMOSTRACA. /// // 5 ' Legion First— BRANCHIOPODA. // Order I.— PHYLLOPODA. /J Family 1 — APODIDiE, containing one Genns . . Apus. Family 2 — NEBALIADAE, containing one Genus . . Neb alia. Family 3 — BRAN CHIPODIDjE, containing two Genera { A « £> * f' Order II — CL ADO CERA. jo’.Sz f Daphnia. £ Moina. Family 1—DAPHNIAD^ containing six Genera . . ®0SMINA Family 2 — POLYPHEMIDiE, containing two Genera . j" Macrothrix. SlDA. ^Daphnella./^ Polyphemus. Eyadne. Family 3 — LYNCEIDiE, containing seven Genera "Eurycercus* Chydorus. Camptocercus. .<{ Acroperus. Alona. Pleuroxus. JPeracantha. Legion Second — LOPHYROPODA. Oedee I— OSTRACODA. /if Family 1 — CYPRIDIDiE, containing five Genera ''Cypris. Candona. Cythere. Cythereis. ^Cypridina. Order II — COPEPODA. />■:,. Family 1 — CYCLOPIDiE, containing four Genera . . Cyclops. Canthocamptus. Arpacticus. Alteutha. (Diaptomus. Family 2 — DIAPTOMIDiE, containing three Genera . < Temora. (. Anomalocera. Family 3 — CETOCHILIDiE, containing one Genus . Cetochilus. * * * * Placed here provisionally, Genus Notodelphys. SYSTEMATIC ARRANGEMENT. 15 Legion Thied — PiECILOPODA. o Oedee I-SIPHONOSTOMA. 2#0 Tribe 1— PELTOCEPHALA. Family 1 — ARGULIDiE, containing one Genus . . Aegultts. Family 2 — CALIGIDiE, containing four Genera Family 3 — PANLARIDiE, containing two Genera . . { Pandaeus A Family 4 — CECROPIDiE., containing two Genera . . LmtAEGUS Tribe 2— PACHYCEPHALA. Family 1 — ANTHOSOMADiE, containing one Genus . Anthosoma. Family 2 — ERGASILID2E, containing one Genus . Nicothoe. Oedee II— LERNEADA3. 36J Tribe 1 — AN CHORASTOM ACEA. Family 1— CHONDRACANTHIDiE, containing two J Chondeacanthus, Genera I Leenentoma. Tribe 2— ANCHORACARPACEA. Family 1 — LERNEOPODADJE, containing one Genus... Leeneopoda, Family 2 — AN CHORELL AD JE, containing one Genus... Anchoeella. Tribe 3— ANCHORACERACEA. Family 1 — PENELLADJE, containing one Genus . . Leeneonema. Family 2-LERNEOCERAD.E, containing two Genera { ENTOMOSTRACA.* Syn. Entomostraca, Muller , Entomostraca, 1785. — latreille , Precis des Caracteres gener. ; Hist. Nat. gen. et part, des Crustac. ; Genera Crustac. et Insectornm ; Cnv. Begne Animal. — Leach, Edinburgh Encyclop. ; Encyclop. Britann. ; Diet, des Sc. Nat., xiv. — Dumeril, Zoologie analytique. — Risso, Hist. Nat. des Crust, des Envir. de Nice. ; Hist. Nat. de l’Eur. merid. — Desmarest, Consid. gen. sur les Crust’ — J. F. Gray, Synops. of Cont. of Brit. Mus., 1812. Aspidostraca or Entomostraca, and Siphonostoma, Burmeister, Organization of Trilobites (Bay Society’s edit.), p. 31. Monoculus, Limans , Syst. Nat., 1st edit., 1735 ; et edit, subseq. ; Eaun. Suec., 1st edit., 1716. — Fabricius, System. Entomolog. ; Entomolog. Systemat. — Cuvier , Tab. element. — Cuvier et Dumeril , Anatomie comparee. — Geoffroy, Hist, abreg. des Ins. des Envir. de Paris. — Manuel, Encyclop. method. BranchiopteRES and Entomostraces, Blainville, Princ. d’Anat. comp. Les Monocles, Jurine, Hist. Nat. des Monoc. des Envir. de Geneve. Crustaces sessiliocles, Lamarck, Syst. Anim. s. Yert., 1801. Branchiopodes, Lamarck, Hist. An. s. Yert., 1st edit., 1818. — Bose, Man. de l’Hist. Nat. des Crust. Character . — The Entomostraca may be characterised by their being all aquatic ; by their being covered with 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 envelopes the body of the animal ; by their having- branchiae attached either to the feet or organs of masti- cation ; by their feet being jointed, and all more or less * From f vrofioQ, an insect ; and oorpaxov, a shell. PH1LL0P0DA. 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 — BRAN CHIOPOD A. * Branchiopoda {pars), Lamarck, Hist. An. s. Yert., 1818. — Latreille, Cuv. Hegne Anim., 1829. — M. Edwards, Hist. Nat. Crust., 1840. Monoctjltjs, Linnaeus ; Fabricius ; Latreille (minus Lynceus), Prec. des Car. gen. Character . — Mouth furnished with organs fitted for mastication ; branchiae 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.f 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. — Eesmarest, Consid. gen. Crust., 357. — J. E. Gray, Synops. Brit. Mus., 1842. — Burmeister, Organiz. of Trilobites, 34. — Lucas , Explor. Sc. de l’Algerie, Crust., 81. Phyllopa, Latreille, Cuv. Hegne Anim., iv, 171. Branchiopodes Lamellipedes and Branchiopodes Geans (in part), Lamarck , Hist. An. s. Yert., v. Character. — Body either naked or having only the head and thorax covered by the carapace ; feet numerous, * B payxta, branchise or gills ; and ttovq, a foot, f $v\\ov, a leaf ; and novg, 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 — APODIDiE. Apus, M. Edwards, Hist. Nat. Crust., iii, 356, et auctorum. Phyllopoda, Leach , Edin. Encyelop., vii, art. Crustaceology. ApoDiDiE, Burmeister, Organization of Trilobites, 34. Character. — Antennae 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/ tom. x, published at Berlin, in 1732. He there gives a figure and description of an insect, which he calls “ vom Floss-fussigen seewurm mit dem 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 Scolopendra aquatica scutata. <£ As long as the insect lives,” he says, “ so long does it continue APODIDJE. 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/5 (p. 152.) About the same time a number of specimens of the same animal were found in Kent by theRev. Mr. Littleton Brown, F.R.S., who, in August 1 7 36, 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 Transactions5 for 1738, No. 447. “ I brought it,55 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 25tli, within two days the pond was observed to swarm with them, by a farmer watering his cows there.55 (p. 153.) Linnaeus, in his ‘Fauna Suecica,5 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 Schoefier, who in his monograph ‘Der Krebsartige Kiefenfuss,5 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,5 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 ‘ Naturforscher5 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,5 1816. Bose, Latreille, Desmarest, and Milne Edwards have repeated Schoeffer’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 Gaede* and Berthold.f For the fullest account, however, of the anatomy and physiology of the Apus, since Schoeffer’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 history of this curious animal. 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. h), we see a number of well-marked lines running obliquely, in an arched form, and being reflexed. These, according to Zaddach, are canals, and were pointed out by Gaede and * Beitrage zur Anatomie der Insecten, Wiedemann’s Zoologisclies Ma- gazin, 1817. f Isis, 1830. X Be Apodis cancriformis ; Schceff., Anatome et Historia evolutionis. Bonnse, 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 interiorly. 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 Lynceidse, 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. b , c). 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. b, 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. a, 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 styliform 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 Schoefier 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 Schoefier calls false teeth* (one being round and possessing very short setae, 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 given of this pair of feet, being taken from the organ in situ , these parts are not exhibited. APODIDiE. 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 Schoeffer denominates a false claw (corresponding to the flat claw-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 Schoeffer 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 Schoeffer 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. Schoeffer considers this to be the situation of the organs of generation. The eleventh (t. I, f. g) 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, are 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 APODIDiE. 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 Schoeffer 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 ; Schoeffer 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. Schoeffer, 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, calm weather,” says Schoeffer, “ 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 Cy prides, 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, 1838, 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.* Schoeffer, Berthold, and Zaddach had considered them to be hermaphrodites ; but in all probability the males will be found, as in the case of the Daphnise, to exist at some particular season of the year, and perhaps in small * Isis, 1834, p. C80; Froriep’s Kotizen, 1833, pp. 38, 148; Burmeister, Organ, of Trilobites, Ray Soc. edit., p. 40, 1846. APODIDjE. 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 Daphnise, &c., to be hereafter described, has been ascer- tained. Schoeffer 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.” + 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 extremity. The antennae 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 antennse, with the three setae, are even more largely developed still ; the eye, too, has become larger. After one or two days more the animal 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 may be observed the eyes, of a black colour. The antennae 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 are 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 days they 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 about twenty times in the space of between two and three months, at which time they seem to have attained their full size. Schoeffer 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 Daphnise. Schoeffer 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.* Attovq, Frisch, 1732. Apus, Schaeffer, Latreille, Bose, & c. Monoculus, Linnaeus, Fabricius. Binoculus, Geoffroy, Leach , Diet. Sc. Nat., xiv, 538. Limulus, Muller , Lamarck. Triopes, Schrank. 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 ttovq, a foot. 30 BRITISH ENTOMOSTRACA. 1. Apus oancriformis. Tab. I, figs. 1, 2, 3. Monoculus cauda biseta, Linnaeus, Faun. Suec., 344, No. 1181, 1746. Apus cancrieormis, Schaffer, Mon. d. Krebsart. Kiefenf., 1. 1-5, 1756. — Latreille, Hist. Nat. des Crust., iv, 193, 1. 19-27 ; Gen. Crust, et Ins., ii, 15. — Savigny, Mem. sur les Anim. s. Verteb., part i, p. 63, t. 7, f. 1. — Bose, Hist, des Crustac., ii, 243. — Leach, Edinb. Encyc., vii, 384, No. 4. — Besmarest , Consid. gen. sur les Crust., 360, t. 52, *f. 1. — Guerin, Iconogr. Regn. Anim. Crust., t. 34, f. 3. — M. Edwards, Hist. Nat. des Crust., iii, 360; Icon. Regne Anim., edit. Crochart, Crustac., t. 75, f. 1. — Berthold, Isis, 1830, t. 7, p. 685. — Zaddach, de Ap. Cane. Anat. et Hist. Evolut. — Koch, Deutsch. Crustac. H. xxxv, t. 4. Apus montagui, Leach, Enc. Brit. Supp., i, 405, t. 20, f. 1-3. Monoculus apus, LAnnmus , Syst. Nat., edit. lOtli, 1758, i, 635, No. 3; edit. 12th, 1058, No. 3. — Gmelin , Syst. Nat., edit. 13th, 3006, No. 3. — Scojooli, Entomol. Carniol., 413, No. 1138. — LesTce, Anfang. der Naturges., 493. — Eabricius, Spec. Insector., i. 372, No. 3; Entomol. Systemat., ii, 488, Supp. 305. — Voschge , Der Naturforsch., x, 60, t. 3, f. 1-10. Binoculus cauda biseta, Geoffroy, Hist, abreg. des Ins., ii, 660, t. 21, f. 4. Binoculus palusteis, Muller , Zool. Dan. Prodrom., No. 2407, 1776. Branchipus cancrieormis, Schaeffer, Element. Entomol., t. 29, f. 1-5. Limulus palusteis, Muller, Entomostraca, p. 127. Limulus cancrieormis, Jjamarch , Hist. An. s. Vert., v, 215. Triopes palusteis, Schranlc, Eaun. Boic., p. 251. Triops cancrieormis, Oken, Eehrbuch der Naturg., iii, 398. Floss-eussigen seewurm, Frisch, Insect, in Deutsch., x, t. 1, f. a-g (clttovq). Scolopendra aquatic a scutata, Klein, Phil. Trans, for 1737, p. 150, t. 1, f. 2 a-d. — Brown , Phil. Trans., 1737, p. 153. Kieeeneuss, Sulzer, Die Kennzeich. der Insect., 197, t. 24, f. 153. Description. — This species is about two inches and a half long, and one inch and a half diameter ; of a brownish- NEBALIADiE. 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 — NEBALIADiE. Neb alia, Leach , Desmarest , Latreille , M. Edwards, 8fc. Character. — Antennae two pairs, large and ramiform ; eyes, two, pedunculated ; 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 Pabricius was the first who described any species of this genus. In his ‘ Fauna Groenlandica,5 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 4 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. rostratus , and says it is the largest species of that genus he had ever found in England. Dr. Leach, in his 4 Naturalises 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, 44 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 4 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, Bose, and Desmarest, Latreille, Olivier, and Bisso ; 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 4 Ann. des Sc. Nat., t. xiii, 1828, he shows from its structure, which we shall describe shortly, that it does not belong to the Decapoda Macroura, but in reality must be placed amongst the Branchiopoda ; an opinion which he confirms in the 4 Ann. des Sc. 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. Eabricius, that it carries its eggs under the body during the winter, and NEBALIADtE. 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 d). They are 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 size at the base, becomes much narrower at its inferior half; 2d, a large mem- branous plate, nearly as long as the internal branch, to which it is attached at its upper external part ; and, 3d, another membranous plate, placed between the two preceding, and attached also to the upper and external edge of the internal branch. NEBALIADiE. 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 inferior 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 Cyclopidae. 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 antennae 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'Andrew dredged it from a considerable depth amongst the Shetland Isles. This family contains only one British genus. 36 BRITISH ENTOMOSTRACA. Genus — Neb alia. Nebalia, Leach, Zool. Miscell., i, 99, 1814 ; Trans. Linn. Soc., xi, 351 . — Thompson, Zool. Research., No. 3, 83. — Besmarest, Cons. gen. Crust., 243. — Latreille , Cuv. Regne Anim., iv, 153. — M. Edwards , Hist. Nat. Crust., iii, 353 ; Ann. Sc. Nat., xiii, 297 ; 2d series, iii, 309. — Bisso, Hist. Nat. Eur. merid., v, 84. — Bose, Man. Hist. Nat. Crust., ii. — Lamarck, An. s. Yerteb., vi. Cancer, 0. Fabricius, Eaun. Greenland., 246, No. 223. — Herbst, Krabben, ii, 111. Monoculus, 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, Eaun. Greenland., 246, No. 223, 1780. Cancer (Gammakelltjs) 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. — Besmarest, Cons. gen. Crust., 243. — Thompson, Zool. Research., iii, t. 11, f. 1. Nebalia glabra, Lamarck, An. s. Yert., v, 345. — Bose, Man. Hist. Crust., ii, 83. Nebalia ciliata, Lamarck, An. s. Yert., v. 345. — Bose, Man. Hist. Nat. Crust., ii, 84, t. 13, bis, f. 3. Nebalia Montagui, Thompson, Zool. Research., iii, t. 11, f. 2. Monoculus rostratus, Montagu, 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 setiferous ; beak of carapace sharp-pointed and moveable ; natatorial feet of moderate length, and setiferous; 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 antennae 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 Bose ; but Leach himself, Hesmarest, 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 Entomostraca; 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. Edwrards, for instance, of the species which he describes under the name of N. Geojfroyi , 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 Ronndstone 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 Nebalia bipes. As the name of Iierbstii 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 law of priority, to restore its original designation. Hab. — 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 — BRANCHIPODIDiE. Branchipiens, M. Edwards, Hist. Nat. des Crust., iii, 364. Branchiopoda, Leach , Diet, des Sc. Nat., xiv. Branchiptjsid^e, Baird , Trans. Berw. Nat. Club, 1845. Branchipldje, Burmeister, Organiz. of Trilobites, Ray Soc. 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 . Chirocephalus. — 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. CHIROCEPHALUS. 39 and not divided into two plates. No appendages at the base of cephalic horns. 1 — Chirocephalus.* Chirocephalus, Prevost, 1803 ; Thompson. Branchipus, M. Fdivards, Fischer , Latreille , Desmarest, 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, e.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 c 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, * From xuP, a hand ; and KttyaXov, head. 40 BRITISH ENTOMOSTRACA. I suspect it to be their only one, and that they are merely aquatic, and never turn to flies, as many insects found in water do.” (p. 72.) Linnseus had, long previously to this, in his c 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 4 Element. Entomol.,’ changed to JBranchipus pisciformis. Schoeffer 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 he mentioned in the ‘ Eauna Suecica’ being a larva, was erroneous, described it, in the tenth edition of the ‘ Systema Naturae/ as a Crustacean, under the name of Cancer 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 st agnails, and confounds it with the animal described by Schceffer. This confusion is kept up by Bose 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 de 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 Schoeffer seems to rest. Fischer de Waldheim, however, and Mr. J. Y. 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 Schoeffer, the other by Prevost ; while the latter makes the species described by Schoeffer as the type of the genus Branchipus, and the one by Prevost as the type of the Chirocephalus. If Schoeffer’ 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 , 8fc. — 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 the antennae, eyes, and mouth. The antennae we shall find, in many of the Entomos- traca, differ in the male and female.* In the Chirocephalus the 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 very great number of exceedingly minute articulations, scarcely perceptible even with the aid of a microscope, * Yide description of Cyclops and of Daphnia. 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. Schoeffer, who describes them in the Brancliipus, calls them tentacula, and Latreille a sort of mandible ; while Prevost and Jurine, 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 Iriangular-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. Fa) 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 antennse, and which 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 given by Shaw, though ill proportioned and roughly executed, is a very fair repre- sentation of it. Jurine’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 Burmeister 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. fC 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 “ barbillons” 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 setae, 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 setae 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 setae. Between the first and second segment of the abdomen we see in the male the organs of generation, and in the female the external ovary or oviferous pouch. The male CHIROCEPHALUS. 47 organ appears to be double or bifid, cylindrical, transparent, and, according to Schoeffer, 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 Schceffer 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 Daphniae, 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 them 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 they 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 Chirocephalus 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. Progs, 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 wmdd 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 antennse, 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, according 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, I 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 setae. 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. m., 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 setae 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 antennae had diminished in length in proportion to the body. On the 11th, seven p. m., about 120 hours after birth, 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 further. 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. Chirocephalus diaphanus, Prevost, Journ. de Phys., 1803, lvii, 37, 1. 1, f. 1-3. — Jurine , Hist. Monoc., 201, t. 20-22. Branchipus Prevostii, Fischer, Bull. Soc. Imp. Nat. Moscou, vii, 1834. Chirocephalus Prevostii, Thompson, Zool. Research., fasc. vii, t. 3, f. 4, 5 ; t. 4, f. 1, 1834. Branchipus chirocephalus, Guerin, Icon. Reg. An. Crust., t. 33, f. 3. Branchipus diaphanus, M. Fckoards, Hist. Crust., iii, 368. Branchipus paludosus, Desmarest , Consid. gen. Crust., 389, t. 56, f. 2. — Lamarck, Hist. An. s. Vert., 2d. edit., v, 198. 54 BRITISH ENTOMOSTRACA. Cancer stagnalis (Linn.?), Shaw, Linn. Trans., i, 103, t. 9, f. 4, 5. Cancer paludosus (?), Muller , Zool. Dan., t. 48, f. 1-8. — . Herbst, Krabben, ii, 118, t. 35, f. 3-5. Branchipus stagnalis, M. Edwards, Cuv. Regne Anim., edit. Crochart, Crust., t. 74, f. 2. Ino piscina, SchranJc, Paun. Boic., iii, 249, 1803. Marteau d’eau douce, Duchesne, Manuel du Naturaliste. Remarkable aquatic insect, King , Phil. Trans., lvii, 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. Hab. — 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— Artemi a. Cancer, Linn tens, Rackett. Gammarus, Fabricius, Pennant , Herbst. Artemia, Leach, Desmarest, M. Edwards, Joly. Branchipus, Latreille. Artemisus, 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 Pabricius, 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. 56 BRITISH ENTOMOSTRACA. Hitherto it had been described either as the Cancer salinus or the Gammarus salinus, according as authors chose to adopt the name given to it by Linnaeus or Fabricius. 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 c 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/ 1884, 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. AllTEMI A. 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. 2d). 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 Artemiae 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/5 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,55 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 often attributed to the presence of great numbers of the Artemia salina. Indeed the cause of this red colour, which was well known to take place in the salt marshes and reservoirs of salt water at Montpellier, was made, some years ago, the subject of very great discussion in France, before the Institute. M. Payen first maintained the cause to be the pre- sence of Artemiae; M. Duval, however, declared that it arose from micro- scopic vegetables, species of Haematococcus and Protococcus. 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/5 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,55 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.55 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 ca,nal 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,55 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 savans, 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 Buvallii, 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 theDytiscus, 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, lT ay ant pas, par un tres bon microscope, vu aucun autre chose que 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 the vessel or against any foreign bodies she may meet with ARTEMI A. 61 in the water ; and in spring and summer these moultings 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 sauna. Tab. II, figs. 2-4. Artemia s alina, 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 , RegneAnim., iv, 174. Cancer salinus, Linnaeus, Syst. Nat., 10th edit., i, 634 ; 12th edit., i, 1056. — Gmelin , Syst. Nat., 13th edit., 2993. — Eackett, Trans. Linn. Soc., xi, 205, t. 14, f. 8-10. Gammares salines, Fabricius, Entomol. Syst., ii, 518. — Pennant, Brit. Zool., iv, 22, No. 35. — Herbst, Krabben und Krebse, i, 145. Artemises salines, Lamarck, Hist. An. s. Yert., 2d edit., v, 199. Artemis salines, Thompson, Zool. Research., No. 5, 104, t. 1, f. 1-10, t. 2. Branchipes salines, 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. 62 BRITISH ENTOMOSTRACA. Abdomen bilobed at extremity, each lobe giving off several short setae. Hab. — Salt-pans at Lymington, Hants ; Schlosser, Rackett, S. Stevens, Esq., 1848; British Museum. Order II— CLADOCERA* Cladocera, Latreille, Cuv. Regne Anim., iv, 151. — Burmeister , Beit, zur Naturg. der Rankenfuss. Daphrides, Straus , Mem. Mus. d’Hist. Nat. v. Daphnoides ou Cladoceres, M. Edwards, Hist. Nat. Crust., iii, 372. — — Lucas , Explor. Sc. de l’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. Eeet 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— DAPHNLAOE. Daphnia, Muller * Haphnides, Straus, Mem. Mus. d’Hist. Nat., v. Haphnidiens, M. Edwards, Hist. Nat. Crust., iii, 374 (exclus. 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. j Bibliographical History . — Swammerdam is the first author we know that has taken notice of any of the * KXadog, a branch ; and leepag, a horn. DAPHNIADiE. 63 Daphniadae, though he mentions that a species had been observed before his time by Goedart, and named by him “ pou aquatique.” * In his 4 Historia Insectorum gene- ralis/ published at Utrecht in 1669, he gives a pretty full description of a species of Daphnia, which is evidently the Pulex. He calls it Pule x 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 ‘ Bin ax rerum Britannicarum/ &c. London, 1677, mentions the Haphniae, 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 che si trovano negli animali viventi/ Firenzi, 1684, gives three figures of a species which Muller quotes as the Pulex (his Pennata), but which are so very bad, that it is difficult to make them out. He calls them by the name of “Animaletti aquatici.” 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 stagnanti, e ne* pozzi, osservati col microscopia.” Bradley, in his ‘ Philosophical Account of the Works of Nature/ 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. T Vide Leyden edition, 1737. 64 BRITISH ENTOMOSTRACA. “ 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 l’histoire d’un genre de Polypes d’eau douce/ 1744, takes notice of, and figures, a species of Daphnia under the name of j Vuceron branchu, which seems 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, 1746. Linnaeus, in his ‘ Systema Naturae/ 4th edition, 1744, describes the same species shortly, under the name of Mono cuius pulex arbor escens, and in his ‘ Fauna Suecica/ 1st edit. 1746, and ‘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 D. pulex. He 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 Pou aquatique , which Muller quotes DAPHNIADiE. 65 as his B. sima, but which Straus says is not so, but is his B. macrocopus. The figures which Joblot gives are very indifferent, and it is not easy to say what species they are meant to represent. Schceffer, in his Memoir ‘ Die griinen Arm -Polypen die geschwanzten und ungeschwanzten zackiger Wasserflohe/ 1755, describes at great length two or three species, under the name of Geschwanzten zackiger Wasserjtoh , and Un- geschwanzten zackiger Wasserjtoh , or water-Jlea with a tail , and water-Jlea 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 B. pulex and sima , and gives a sketch of the head only of a third, which, being provided with a tail, has been quoted by Muller and Straus as the B. 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 ‘ leones Insectorum circa Ratisboniam indiginorum/ 1766, the* same author figures the B. 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, Monoculus pulex , andLedermliller, in his ‘Mikroskopischen Gemuths und Augen-ergotzung,’ 1763, gives an in- different figure of a species, which however is easily recognisable as the same. Geoffroy, in his 6 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 Muller quotes as his quadrangula , but which Straus, I think more correctly, considers the pulex. 5 66 BRITISH ENTOMOSTRACA. Goeze, in the ‘ Naturforscher,’ 1775, describes the same species, under the name which Swammerdam had given to it, the Pulex arborescens ; and Sulzer, in his ‘ Abjekiirzte Geschichte der Insecten/ 1776, gives a very indifferent figure of what he calls Monoculus pulex , but which is evidently the Daphnia vetula. Muller, in his paper on the Cypris, in the f Philoso- phical Transactions" for 1771, has enumerated several species of Daphnia as occurring in Norway and Denmark, but under the general name of Monoculus. In 1776, however, he established the genus Daphne, in his ‘Zoologiae 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 THistoire des Insectes/ 1778, gives a good many details concerning this family, pointing out two or three errors into which Swammerdam had fallen, and giving very accurate descriptions of some portions of their anatomy. He describes at length, and figures very nicely and with 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,’ 1779, mentions one species, the pulex ; and Eiehhorn, in his ‘ Beytrage zur Naturgeschichte der kleinsten Wasserthiere,’ 1781, gives a tolerable figure of the same species. Gmelin, in his edition of the c Sy sterna Naturae/ 1788, gives all the nine species of Muller, and adds to them the Monoculus pediculus, which Muller had already formed into a genus by itself, the Polyphemus . Manuel, in the ‘Encyclopedic methodique/ 1792, DAPHNIADiE. 67 gives all Muller’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,’ 1802, gives an indifferent figure of a species taken when in its young state, and which appears to be the Daphnia 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 offer the least opposition.” Latreille, in his ‘ Hist. Nat. gen. et part, des Crustaces et Insectes/ 1802, enumerates all Muller’s species, re- taining his names ; and they are given in the same manner by Bose, 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 1805, published a detailed account of the anatomy of two species, the sima {vetula) and longi - spina of Muller, in his ‘Beyt. zur Naturg. einig. deuts. Monoculus-arten.’ Previous to his time, Schceffer, De Geer, and Muller, were the only authors who had attempted any particular anatomical details, and this 68 BRITISH ENTOMOSTRACA. memoir of Ramdohr added much to what they had done. Lamarck, in his ‘ Hist. Nat. des Anim. sans Verteb.’ first edit. 1818, describes two of Midlers species, and Samouelle, in his ‘History of British Insects/ 1819, gives one. In Rees’s ‘Cyclopaedia/ 1819, we have all Midler’s species ; while Leach, in his article “ Crustaceology,” in the ‘Edinburgh Encyclopaedia/ 1828, only mentions the jpulex. From the time when Midler’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 Ramdohr 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 Envir. de Geneve,’ 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 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 du Museum, d’Hist. Nat.’ 1821. 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 information with regard to their economy, which had escaped all the previous writers. Jurine describes six species, which had not been observed by Muller, and Straus three, though some of them seem to be only varieties. Desmarest, in his work ‘ Consid. gen. sur les Crust./ 1825, 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 ones. DAPHNIADtE. 69 Gruithuisen has published a very interesting memoir upon the Baphnia sima of Midler, in vol. xiv of the ‘Nova acta Physico-Medica Academic Cesarise 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 Muller. In M, Edwards’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, 8fc. — 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 antennse (t. VIII, f. a, b, b ; t. X, f. la, 4 a). 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 “ barbillons55 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 Muller5 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 a). Jurine describes them very particularly in the jpulex, calls them “harpons,55 and says, they occupy the place of the “ barbillons55 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 antennse. They consist each of a single joint at the base (t. VIII, f. a, a), 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 every direction. DAPHNIADiE. 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 pulex , 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 ; unequal , 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 Muller, 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 Muller and De Geer repeat this, — an opinion which has also been adopted, and proved correct by Straus and J urine. 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 ENTOMOSTRACA. 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, g , and f. c) consists of a flattish body, compressed at the sides, and has at its extremity a large lobule, furnished with several setse. It is fixed to the posterior part of the base of the beak, is very moveable upon its antero-superior angle, and by means of powerful muscles (f. ■ . . -tap*** 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. Sida. — 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, Muller , Zool. Dan. Prodrom. Daphnia, Muller , Entomostraca. — Straus , Desmarest , latreille , Lamarck , Bose, Leach , M. Edwards, &c. Monoculus, Linnaeus , JPoda, Blumenbach, Be 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. Ion - gispina ; Tab. XI, figs. 3, 4, 5. Var. magna. Monoculus pulex, Linnaeus , 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. — Muller , Eann. Insect. Eriedrichsdalens. 95. — Blumenbach , Handbuch der Naturg., 399. — Manuel , Enc. meth., vii, 722, No. 15, t. 265, f. 1-4. — Fabricius , Entomol. Syst., ii, 491. 90 BRITISH ENTOMOSTRACA. Monoculus pulex, Leach , Encyc. Brit., art. Entomol. — Jurine , Hist, des Monoc., 85, t. 8, f. 1-2, t. 11, f. 1, 3, 5. — Cuvier , Tab. Element., 455. Daphne pulex, Muller , Zool. Dan. Prod., 199, No. 2400, 1776. Daphnia pulex, Latreille, Gen. Crust, et Ins., i, 17 ; Hist. Nat. gen. et part, des Crust., iv, 223 ; Regne Anim. Cuv., edit. 2d, iv, 171. — Lamarck , Hist. Nat. des An. s. Yert., edit. 2d, v. 181, No. 1. — Samouelle , British Insects, 80. — Straus , Mem. du Mus. d’Hist. Nat., v, t. 29, f. 1-20. — Desmarest , Consid. gen. sur les Crust., 372., t. 54, f. 3, 4. — Baird, Ann. Nat. Hist., i, 254, t. 9, f. 1-12 (for details). — M. Edwards, Hist. Nat. des Crust., iii, 379. — Guerin, Iconograph. Crust., t. 33, f. 1. — O. Fabricius, Eaun. Greenland., 263. — Leach, Edin. Encyc., vii, art. Crustaceol. Daphnia pennat a, Muller, Entomost., t. 12, f. 4-7. — Bose, Man. d’Hist. Nat. des Crust., ii, 280. — Schrank, Faun. Boic., iii, 264. Monoculus pulex aeboeescens, LAnnaus, Syst. Nat., 4th edit., 96; Faun. Suec., 344. Pulex abbokescens, Swammerdam, Hist. Ins. Gen., 76, 1. 1, f. a, b,c; Biblia Naturae, 86, t. 31, f. 1-3. — Goeze, Naturforscher, pt. 7. Monoculus pulex eamosus, De Geer, Mem. pour servir a FHist. Ins., vii, 442, t. 27, f. 1-4. Daphnia eamosa, Koch, Deutsch. Crust., h. xxxv, t. 18. Daphnia media, Koch, Deutsch. Crust, h. xxxvii, 1. 1. Daphnia ephippiata, Koch, Deutsch. Crust., h. xxxv, 1. 16. Pucebon beanchu, Trembley, Mem. pour servir a l’Hist. d’un Gen. de Polypes d’eau douce, 92, t. 6, f. 3jo, & f. 11. Watee-elea with beanched hoens, Baker, Emp. for Micros., 302, t. 12, f. 14. Pou aquatique, Joblot, Observ. d’Hist. Nat., i, pt. 2, 105, t. 13, f. P, Q, R. Le Peeeoquet d’eau, Geoffroy , Hist, abreg. Ins., ii, 655, No. 1. Yeemes minimi eubei, Merrett, Pinax Her. Nat. Brit., 207. Animaletti aquatici, Bedi, Osservazioni, t. 16, f. 5 ; Opere, ii, t. 16, f. 5. DAPHNIA. 91 Monoctjltjs, Bradley, Phil. Account of Works of Nat., 202, t. 25, f. 5. Le Ptjceron verdatre, Ledermuller, Mikroskop. Gemiiths. Augen- ergotz., 146, t. 75, f. 2. Var. a. Daphnia longispina, Muller, Entomost., 88, t. 12, f. 8-10. — Latreille, 1. c., iv, 226. — Bose, 1. c., ii, 283. — Bamdohr , Beyt. zur Naturg. ein. Deutsch. Monoc. arten, 24, t. 7. — Lamarck, 1. c., v. 127. — Straus, 1. c., t. 29, f. 23-4. — Besmarest, 1. c. 372. — M. Edwards, 1. c., iii, 380. — Koch, Deutsch. Crust., h. xxxv, t. 17. Monoculus longispinus, Fabricius, Ent. Syst., ii, 492. — Manuel, 1. c., 718, t. 265, f. 5-7. — Be Geer, 1. e., vii, 442, t. 27, f. 1-4. — Schceffer, Die grim. Arm-Polyp., 5 9, t. 2, f. 1 . Var. /3. Daphnia magna, Straus, 1. c., t. 29, f. 21-2. — Besmarest, 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. Hab. — In almost all pools, and ditches of standing water, round London, &c. ; common from April to ^ J 11 T n 349, 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 serrse of dorsal margin extending to near the commencement of the head. The filaments of the antennae 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 the articulations, their relative size, and the number and distribution of the filaments of these antennae, are the same in all the species of the genus Daphnia. 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. Hab . — Pond on Blackheath ; April, June, Sept. 1848. 3. Daphnia Schcefperi. Tab. VII, figs. 1, 2 ; Tab. VIII, figs, a — i. Gescjtwanzten zackiger Wasserfloh, Schceffer, Die griinen Arm- Polyp., t. 1, f. 8, 1755. Branchipus con chiformis primus, Schaffer , Element. Entomol., t. 29, f. 3-4. Daphnia pulex, Koch , Deutsch. Crust., h. xxxv, t. 15. Daphnia, Eymer Jones, Outlines of Animal Kingdom, 330, f. 155. — Eichhorn, Beytrage zur Naturg., t. 5, f. H (after Sehoeffer). 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 ENTOMOSTRAOA.. part, the carapace is marked with a series of circular, flat- looking canals (t. VII, f. 1 a), which resemble very much the canals described on the carapace of the Apus, 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 the pulex. 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 jpulex; consisting of a short tubercle, which sends off several short setae. 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 sinuation 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 are 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. Hab . — 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, Muller , Zool. Dan. Prod., No. 2399, 1776. Daphnia vetula, Straus, Mem. Mns. Hist. Nat., v, t. 29, f. 25-6. — Baird, Ann. Mag. Nat. Hist., i, 255, t. 9, f. 18. Daphnia sima, Muller, Entomostraca, 91, t. 12, f. 11-12, 1785. — Latreille, Hist. Nat. gen. et part. Crust., iv, 228. — Bose , Hist. Nat. Crust., ii, 280. — Ramdohr, Beytr. zur Naturg., 18, t. 5-6. — Gruithuisen, Nov. Act. Phys. Med. Acad. Csesar. Nat. Cur., xiv, pt. 1, 399, t. 24, f. ]-6. — Desmarest, Consid. gen. Crust., 373. — Lamarck, Hist. An. s. Vert., v, 182. — M. Bdwards, Hist. Nat. Crust., iii, 382. — Koch, Deutsch. Crust., h. xxxv, t. 12. 96 BRITISH ENTOMOSTRACA. Monoculus simus, Gmelin, Syst. Nat., 1 3th edit., i, 3000, No. 25, 1788. — Manuel , Encyc. meth, vii, 723, No. 18. — Jurine, Hist. Nat. Monoc., 129, t. 12, f. 1. Monoculus LiEVis, Fabricius , Ent. Syst., ii, 492, 1793. Monoculus exspinosus, De Geer , Mem. pour servir a PHist. 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, Schaeffer, Die grim. Arm- Polyp, 229, 1. 1, f. 9. Monoculus nasutus (?), Jurine, 1. c, t. 13, f. 1. Monoculus pulex, Sulzer , Abgekurzte Geschichte derlnsecten, 266, t. 30, f. 10 *. 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 in pulex, 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 antennae are jointed and plumose, but not so decidedly as in the preceding. The sixth segment of the body has about three 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. Hab. — 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. quadrangula . Monoculus reticclatus, Jurine , Hist. Nat. Monoc., IB 9, 1. 14, f. 3, 4. Daphnia reticulata, 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, Muller , Entomost., 90, t. 13, f. 4. — Latreille, Hist. Nat. Crust., iv, 227. Monoculus'quadrangula, Gmelin, Liim. Syst. Nat., 2999, No. 24. Monoculus qu adran gularis, Manuel, Enc.meth., vii, 723, No. 15. t. 265, f. 8-9. Monoculus quadrangulus, Fabricius, 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 ephippium in this species differs considerably from that of the pulesc. 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 98 BRITISH ENTOMOSTRACA. The antenna consists of a long, 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 pulex. 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. Hah. — 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 — Fabricius, Entomol. Syst., ii, 493, No. 15. — Manuel , Enc. meth., 723, No. 19, t. 265, f. 10-12. — Jurine , Hist. Monoc., t. 13, f. 3, 4. Pasithea rectirostris, Koch, Deutsch. Crust., h. xxxv, t. 24.* Pasithea gibba (?), Koch , 1. c., h. xxxvi, t. 16. Daphnia macrocopus (P), 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 setee. 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 a), 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 Fasithea, having been used in zoology twice previously, cannot be retained. 102 BRITISH ENTOMOSTRACA. 2. Moina brachiata. Tab. IX, figs. 1, 2. Monoculus brachiatus, 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 setae 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. Hab. — I first found this species in a stagnant pool in old St. Pancras 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. Bdwards, Hist. Nat. Crust,, iii, 384. — Muller (?), Entomost. Lynceus, Besmarest, Cons. gen. et part. Crust,, 370. Monoculus, Jurine , Hist. Monoc. Geneve. Acanthocercus, Schodler, Erichs. Archiv, 1846. <9 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 (?), Muller, Entomost., t. 13, f. 1, 2. Monoculus laticornis, Jurine, Hist. Monoc., t. 15, f. 6. Lynceus laticornis, Besmarest, 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^ fomc't&O n* The inferior antennae or rami are strong and large (t. XV, f. 2 a). The posterior branch has four setae ; three a, rfJuc from the extremity of the last articulation, and one from the extremity of the second. The anterior branch has five setae, 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. * M aKpog, long; and 0pi%, a hair. 104 BRITISH ENTOMOSTRACA. Intestine straight, not convoluted ; but more distinctly curved at its upper extremity than in the other Daphniadse. Hab. — Pond at Southall, Middlesex, June 1841; Sept. 1849. Pond at Highgate, July 1842; Sept. 1849. Belfast, May 1849, W. Thompson, Esq. 2. Macrothrix roseus. Monocultjs eosetjs, Jurine, Hist. Monoc., t. 15, f. 4,5. Lyncetjs eoseus, Desmarest, Cons. gen. et part.,, 376, t. 54, f. 8-9. Daphnia eosea, M. Edwards, Hist. Nat. Crust., iii, 384, No. 14. — Yarrell, British Eishes, ii, 93, vignette. Maceotheix eosetjs, Baird , Trans. Berw. 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 Yen dace ( Corre - gomes Willughbii). 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. 105 Genus 4 — Bosmina.* Daphnia, M. Edwards, Desmarest , Baird. Monoculus, Jurine. 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. 2894 ; Ento- most, 76, t. 10, f. 7, 8. — Latreille, Hist. Nat. Crust., iv, 206. — Eabricius, 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, Deutsch. Crust., h. 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 seventh 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 Eingal. f As the terms Eunice and Eunicae have been already used in zoology, and as this genus is not characterised by Koch, I have preferred retaining the name I applied to it in 1845. 106 BRITISH ENTOMOSTRACA. to make out this articulated structure distinctly. Like the antennules of the Daphniadae and Lynceidae, 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 antennae, 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-water of London supplied from these two sources, SIDINA. Genus 1 — Sid a. Sid a, Straus, Mem. Mus. Hist. Nat., v; M. Edwards, Baird, Dana. Daphnia, Muller, Latreille, Bose , &c. Monoculus, Be Geer, Jurine , &c. Character. — One branch of inferior antennae with three, the other with two articulations, large and powerful. Superior antennae of moderate size. SIDA. 107 1. Sida crystallina. Tab. XII, figs. 3, 4 ; Tab. XIII, fig. 1 a-h. Daphne crystallina, Muller, ZooL Dan. Prod., No. 2405, 1776. Daphnia crystallina, Muller , Entomost., 96, 1. 14, f. 1-4. — Latreille, Hist. Nat. Crust., iv, 230. — Bose, 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, Linn. Syst. Nat. edit. 13th, i, 3000, No. 29. — Manuel, Enc. meth., vii, 724, t. 265, f. 15-18. — Fabricius , Ent. Syst., ii, 493. Monoculus elongatus, Be 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 setae proceeding from it, and terminates in two long, stout daws, 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 BRITISH 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 setae, 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 setae from its upper edge. The mandible (t. XIII, f. c ; t. XII, f. 8 a,/) is similar to that of Daphnia Schcefferi, and has a row of cutting teeth on its edge. The labrum (t. XII, f. 3 a ,g) 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, e). There does not appear to be any organ corresponding to what has been described in Daphnia as the caecum. 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 a main stalk of two articulations, one of which has four setae, 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 with nine or ten short filaments, and one longer and plumose. The four succeeding pairs are more like each other, but differ somewhat from the first pair. They each (t. XIII, f. e,f) possess a small triangular plate fixed upon the edge of the main stalk, and taking the place of the setae which are 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. XIII, f. cj) differs from all the others. Each foot consists of three 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, W. 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. no BRITISH ENTOMOSTRACA. Superior antennae (f. 4 b) long and rather slender, and provided with two setae at their extremity, of con- siderable length. Inferior antennae or rami 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 o ), 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 setae, 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 b) appears to have a supple- mental plate, which covers it, and which is flat, broad, and curved at the lower extremity. The female has very 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 a great distance at each bound. Hab. — Pond on the edge of the Colne, between Twick- enham and Whitton, Middlesex, July 1841 ; ditch near Richmond, opposite Isleworth, July 1841, August 1849. POLYPHEMUS. Ill Family 2— POLYPHEMID^. P olyphemidhs, 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, Muller , Cuvier , Latreille , Straus , Edwards, Sec,. Monoculus, Linnaeus, Geoffroy, Be Geer, Eabricius , Jurine, Sec. Cephaloculus, Lamarck, Bose. Character. — Head distinct from body. Abdomen long, projecting externally from the shell. I. Polyphemus pediculus. Tab. XVII, fig. 1. Monoculus pediculus, Linnaeus, 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. — Eabricius, Ent. Syst., ii, 502 ; Sp. Ins., i, 374, No. 7 ; Mantissa Ins., i, 240, No. 7. — Sulzer, Insecten, t. 30, f. 8 a . — Manuel, Encyclop. meth, vii, 718, t. 263, f. 1. Monoculus pediculus kamosus, Be Geer, Mem. pour serv. a l’Hist. Ins, vii, 467, t. 28, f. 9-13,1778. Polyphemus oculus, Muller, Zool. Dan. Prod, No. 2417, 1776 ; Entomost, t. 20, f. 1-5. — Cuvier, Tab. element, 456. — Latreille, Hist. Nat. Crust, iv, 287 ; Genera Crust, et Ins, ii, 20. — Leach, Edin. 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 , M6m. Mus. d’Hist. Nat., v. — M. Edwards, Hist. Nat. Crust., iii, 389. Monoculus polyphemus, J urine. Hist. Nat. Monoc., 143, 1. 15, f. 1-3. Cephaloculus stagnorum, Lamarck, Hist. An. s. Yert., v, 131. — Bose, Man. d’Hist. Nat. Crust., ii, 247. Le Monocle 1 queue retroussee, Geoffroy , 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 a) 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 setae, 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 Daphniae, and, as Jurine says, seems to serve as a rudder. The heart is situated at the same part of the body as in the Daphniae, 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 Cyclopidce 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 ephippium, or saddle, which serves exactly the same purpose as in them. The number of young is not so great as in the Daphniae, 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 Muller says “ its head is all eye.”* The males have never yet been noticed by any observer. Hab. — Ditch near Richmond, on the banks of the Thames, nearly opposite Isleworth, 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. Journ., 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 Nokdmanni, Loven , Zoologisk. Bidrag,, 1. 1, 2 ; Ho., Kongl. Yetenskaps. Acad. Hadlingar., t. 1, f. 1-8. — M. Edwards, 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) are four pairs, and arise almost immediately below the eye. They are each com- posed of four articulations, which are all furnished with several strong setae. 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.” — Entomost., 118. LYNCEIDiE. 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 Daphnise, 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 — LYNCEIDiE. Lyncetjs, Muller, Latreille, Manuel, 8fc. Daphnides (in part), Straus. Daphnidiens (in part), M. Edwards. Daphnid^e (in part), Baird, Ann. and Mag. Nat. Hist., ii. Lynceid^e, Baird, Trans. Berw. Nat. Club, ii, 150, 1815. 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. — Muller 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. Austrise,’ 1781, p. 536, 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, however, respecting the genus ; and Muller’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 Jurine published his f 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 Muller’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 Muller, by Hesmarest, in his ‘ Consid. gen. sur les Crust.,’ 1825 ; but we have no new infor- Beyt. zur Naturg., p. 37, t. 3, f. d ; 17S1. LVNCEIDiE. 117 mation 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 , 8fc. — 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 Muller 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 antennae, the inferior, or rami, the brain, mouth, and part of the digestive canal. The eye (t. XV, f. 11), as in the Daphniadae, 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 lamellatus, are about twenty in number. The black spot, which Muller 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 “Nomen Lyncei in Zool. Dan. prod, ex punctis binis oceUaribus, quae organa visus absque dubio sunt, indixi.” — Entomost., 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 b), 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 Eurycercus lamellatus the anterior branch sends off from the last joint three long filaments or bristles, and a short one, and one from the extremity of the second and first joints ; while the posterior branch sends off only three long ones and a short one from the last joint. The long setae are each furnished with a joint near the centre, as in Daphnia pulex , and, as in it, are beautifully plumose, while the short setae are neither jointed nor plumose. LYNCEIDiE. 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 Daphniadae. 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 labrum (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 d*). 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 Daphniadae, 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- niadae, 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. 1^) in all the species I have examined is connected to the body by an articulated joint, differing in this very particularly from the Daphniadae. At this joint we see two setae arise, which in some species, as in the JEurycercus 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 macrourus, 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 are five pairs in number (t. XV, f. 1 e-i) ; the first pair are the largest, and consist each of a fleshy sort of body, bent a little, strongly ciliated on its upper edge, and furnished at its extremity with five long and strong setae, which in general project a little beyond the edge of the * The body, as above described, is particularly well seen in the Acroperus harpce. LYNCEIDiE. 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 Daphniadae, con- sisting of branchial plates and finely plumose setae, and have the same functions and uses. These insects are found in stagnant waters and slow- running streams, amongst the Lemnae and Confervae 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 Daphniae, as they pro- duce only a few eggs at a time, generally two or three, with the exception of th zEurycercus lamellatus, which has nearly as many as the Baphnia vetula , and is about the same size. Their mode of reproduction is the same as in the Daphniadae, the intervention of the male more than once not being necessary for fecundating the eggs of the female. In one species, the Chydorus sphcericus , Jurine obtained, by isolating the young successively, fifteen generations ; and in the Alona quadrangular is, f he followed up the moultings and generations for nine successive periods. On the 7th of June he isolated a female, which had eggs ; 8 th June, two young ones born; 9 th, it has moulted, and got two eggs of a clear brown colour; 11th, 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. Entomol./ February 1837, p. 11, M. Audouin communicated the fact of his having had several specimens of a species of Lynceus from the neighbourhood of Warsaw, sent to him by the celebrated Waga, and that he had ascertained tlie 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 hamatus may prove to be the male of an allied species. f Monoculus striatus, J urine. 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; 11th, 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 Jurine to be subject, like the Daphniadae, 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 Daphniadae. The motion of these insects through the water is somewhat different from that belonging to the Daphniadae. 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 the Bosmina longi- rostris , which has also very short rami, situated as in the Lynceidae, has the same kind of motion. f The food of the Lynceidae 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 Pritchard, the Cltydorus sphcericus is the choice food of * Jurine, Hist, des Monoc., pp. 155-6. f Mag. Zool. and Bot., ii, 412. 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. Eurycerctjs. — 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 interiorly 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 antennae 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 — Eurycercus4 Lynceus, Muller , et auctorum . Eurycercus, 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. X From evpvQ, broad ; and KspKog, a tail. 124 BRITISH ENTOMOSTRACA. 1. Eurycercus lamellatus. Tab. XV, figs. 1, 1 a-l. Lynceus lamellatus, Muller, Zool. Dan. Prod., No. 3396, 1776 ; Entomost., 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, Deutsch. Crust., h. xxxvi, t. 9. Monoculus lamellatus, Gtmelin, Linn. Syst. Nat., 3008, No. 62. — Manuel, Encye. 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 Daplinia pulex , and jointed about the middle of their length. Eye large, contained in its funnel-shaped sheath of muscles, areolar ; areolae 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 Daphnia. 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 turned it over two or three times before it has moved. Hab. — Not uncommon in ponds and ditches, during the summer months. Near Isle worth, and elsewhere in the neighbourhood of London. In Yetholm Loch ; and pool on Bowmont Water, near Yetholm, Roxburghshire. Genus 2 — Chydorus. 'JfeO Lynceus, Muller, et auctorum. Chydorus, 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^ericus. Tab. XVI, fig. 8. Lynceus sphjsricus, Muller , Zool. Dan. Prod., No. 2932, 1776; Entomost., 71, t. 9, f. 7-9. — Latreille , Hist. gen. Crust., 207. — Lamarck , An. s. Yert., v, 128, No. 3. — Desmarest , Cons. gen. Crust., 377. — Baird , Trans. Berw. Club, i, 100. — M. Edwards, Hist. Crust., iii, 386. — Pritchard, Micros. Cab., t. 8, f. 3. — Koch, Deutsch. Crust., h. xxxvi, t, 13 {not h. viii, t. 2.) Monoculus sph.®ricus, Gmelin, Linn. Syst. Nat. 3008, No. 60. — Jf^^,Encyc.meth.,vii, 732, t. 268, f. 15-17. — Fabricius, Ent. Syst., ii, 497. — Jurine, Hist. Monoc., t. 16, f. 3. Monoculus inpusorius (Kleinster Schildfloh), Enum. Insect. Aust., 536. — Fichhorn , Beyt. Naturg., t. 3, f. d* Chydorus Mulleri, Leach, Enc. Brit. Supp., art. Annulosa, 1816 ; Diet. Sc. Nat., xiv., 541. Chydorus sph^ricus, Baird, Ann. and Mag. Nat. Hist., ii, 89, t. 2, f. 11-13,1843; 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 setae, 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 half 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 antennae. * Perhaps this may be a new species. Muller quotes this figure of Eichliorn for his L. trigonellus, but it appears to me to be quite distinct. It resembles the sphnericus in shape, except that the inferior extremity of the shell is pointed. Should it prove a new species, we would propose to name it Chydorus Fichhorni. CHYD0RUS. 127 Its motion through the water is more like rolling, as Jurine describes it, than swimming. The mandibles, feet, and superior antennae 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/7* Hab.— Ponds and ditches ; common almost all the year round. __ . 2. Chydorus globosus. Tab. XVI, fig. 7. Chydokus globosus, Baird, Ann. and Mag. Nat. Hist., ii, 90, t. 3, f.1-4, 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 antennae large, with seven teeth, and seven long setae. Inferior antennae or rami (t. XVI, f. 7 b) very short and slender ; anterior branch with four setae, one from the second, and three from the last articulation ; posterior branch has only three from the last joint. Eirst 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. Hob. — 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. - Gems 3 — Camptocercus.* Lynceus, Muller , et auctoruni. Camptocercus, Baird, Ann. and Mag. Nat. Hist., ii ; Trans. Berw. 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. Lyncetjs macrourus, Muller, Zool. Dan. Prod., 2397, 1776 ; Entomost., t. 10, f. 1-3. — Latreille, Hist. Nat. Crust., 207. — M. Bdwards , 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. — Fabricius, Ent. Syst., ii, 499. Camptocercus macrourus, Baird, Ann. and Mag Nat. Hist, ii, 91, t. 3, f. 5, 6, 1843 ; 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 setae 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 * Kafinrog, flexible ; and tctpicog, a tail. ACROPERUS. 129 short, from last ; posterior branch has only three long filaments and one short, from the last joint. Abdomen (t. XYI, f. 9 a) very long and slender, with thirteen well-marked serrae, 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. Hie-hgate ponds. June, July, and Genus 4— Acroperus.* Lynceus, Baird , Trans. Berw. Nat. Club, i. Acroperus, Baird, 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 harpj3. Tab. XVI, fig. 5. Lynceus harp^e, Baird, Trans. Berw. Nat. Club, i, 100, t. 2, f. 17, 1835 . Acroperus harp^e, Baird, Ann. and Mag. Nat. Hist., ii, 91, t. 3, f. 7, 1843 ; Trans. Berw. Nat. Club, ii, 151. Lynceus leucocephalus,Zo^, 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, * Erora aicpog, pointed ; aud 7repag , extremity. 9 130 BRITISH ENTOMOSTRACA. 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 setae from the extremity of last articulation only. The rami and setae 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. Hab. — Pond in Osterly Park ; ditch near Bichmond ; pond on Bowmont Water, Yetholm, Roxburghshire; ™ 1 10 ' T 11 ‘ q. Summer months. 2. Acroperus nanus. Tab. XYI, fig. 6. Acroperus nanus, Baird, Ann. and Mag. Nat. Hist., ii, 92, t. 3, f. 8, 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 harjpce; 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. Hah. — Pond at Norwood Green ; and near Southall, Middlesex, June 1841. Rare. - Genus 5 — Alona. Lynceus, Muller , et auctorum. Alona, Baird, Ann. and 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 quadrangularis. Tab. XYI, fig. 4. Lynceus quadrangularis, Muller, Zool. Dan. Prod., No. 2393, 1776 ; Entomost., t. 9, f. 1-3. Latreille, Hist. Crust., 208. Baird, Trans. Berw. Nat. Club, 100. M. Bdwards, Hist. Crust., iii, 388. Koch, Deutsch. Crust., h. xxxvi, t. 1 5. Monoculus qdadrangulus, Gmelin, Syst. Nat., 3008, No. 61. — Manuel, Enc. metli., viii, 733, t. 268, f. 18-20. Monoculus quadrangularis, Fabricius, Ent. Syst., ii, 498. Monoculus striatus (?), Jurine, Hist. Monoc., t. 16, f. 1, 2. Alona quadrangularis, Baird, Ami. and Mag. Nat. Hist., ii, 92, t.3, f. 9-11,1843; 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 rami (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 harpce l Abdomen (t. XVI, f. 4 c) rather narrow, sinuated near extremity, and serrated for about half its length on the under edge, the serrae 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, 1843 ; 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 Acroperus nanus. Shell of a quadrangular shape, rounded a little poste- riorly, and nearly straight on anterior margin, which * I bad some doubts at first as to this being identical with the Monoculus striatus of Jurine. In his figure the beak is blunter, and the abdomen shorter and rounder-shaped than in my specimens. He gives it the name striatus with a doubt ; and remarks, “ if this species be the truncatus of Muller, 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 have seen the truncatus of Muller, and the quadrangularis 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, I have now little or no hesitation in referring them botli to the 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. Hab. — 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. quadrangular is. 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. Hab. — Pond on Blackheath, April 1848. — 134 BRITISH ENTOMOSTRACA. Genus 6 — Pleuroxus.* Lynceus, Muller , et audorum . 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, Muller, Zool. Dan. Prod., No. 2395, 1776 ; Entomost., t. 10, f. 5, 6. — Latreille, Hist. gen. Crust., 205. — • LamarcJc, 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. — Manuel, Encyc. meth., vii, 733, No. 63, t. 268, f. 24, 25. — Fabricius, Ent. Syst., p. 498. Pleuroxus trigonellus, Baird, Ann. and Mag. Nat. Hist., ii, 93, t. 3, f . 1 3, 1 8 43 ; Trans . Berw. N at. Club, ii, 1 5 1 . 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 setae, one from first articulation, one from second, and two from last. Posterior branch has three setae, all springing from last joint. * Prom TrXtvpov, a side ; and 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 Muller being the first pair of feet. Intestine convoluted, having one turn and nearly half another. Hah. — 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 trigonellus , 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, antennae, 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 Han well and Southall, Middlesex, September 1849. 136 BRITISH ENT0M0STRACA. /> : ■ /’• • ‘A 3. Pleuroxus hamatus. Tab. XVII, fig. 5. Lynceus hamatus, Baird, Trans. Berw. Nat. Club, 100, t. 2, f. 18, 1835. Pleuroxus 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 trigonellm. Inferior antennae or rami with three setae 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.I Lynceus, Muller , et audorum. 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 species. It may perhaps be the male of trigonellus , the cheliform nature of the first pair of feet having a consi- derable resemblance to the structure of that organ in the male Daphnia, and more especially in the male of the Estheria, as represented by Joly in his description of the Isaura cydadoides, ‘Ann. Sc. Nat./ 2d series, xviii, 1843. f Prom 7 rtpag, extremity; and aicavOa , spine. PERACANTHA. 137 1. Peracantha truncata. Tab. XVI, fig. 1. Lynceus truncatus, Muller , Entomost., 75, t. 11, f. 1-6, 1781. — Tatreille , Hist. Crust., 206. — Baird , Trans. Berw. Nat. Club, 100. — M. Edwards, Hist. Crust., iii, 388. — ■ Koch, Deutsch. Crust., h. xxxvi, t. 11. Monoculus truncatus, Gmelin, Linn. Syst. Nat., 3008, No. 64. — Manuel, Enc. meth.,vii,733,t. 268, f. 30-34. — ■ Eabricius, Ent. Syst., 498. Peracantha truncata, 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.ltf), 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. Eirst 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, Besmarest, Cons. gen. Crust. Lophyropoda, Leach , Diet. Sc. Nat., xiv, 524r. — /. E. Gray , Synops. Brit. Mus., 1842. — Burmeister, Beitr. zur Naturg. der Rankenfussen. Branchiopodes erarges {pars), LamarcJc, Hist. An. s. Yert., 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. Beet 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. Regne Anim., iv, 151. — Baird , Mag. Zool. and Bot., i; Trans. Berw. Nat. Club, ii. Ostracins ou Bitestaces, Bumeril, Zoologie Analytique, 1806. Ostrapoda, Straus, Mem. Mus. d’Hist. Nat., vii. Cyproides ou Ostracodes, M. Edwards , Hist. Nat. Crust., iii, 393. Crophyropoda b., Burmeister, Organization of Trilobites (Rav Soc. edit.), 34. Cypridacea vel Ostracoda, Dana, Proc. Amer. Acad. Sc., 1849. Character . — Body inclosed entirely in a covering of two valves, resembling a bivalve shell. Posterior jaws branchiferous. No external ovary. Feet two and three pairs, adapted for progressive motion. This order contains three families, Cypridae, Cytheridae, and Cypridinadae. * Prom \o(pvpog, having stiff hairs ; and novc, foot. ■)■ Prom oarpaKov, a shell. CYPRID.E. 139 Family I — CYPRIDiE. Cypris, Muller , et auctorum . Cyproides (pars), M. Edwards, Hist. Nat. Crust., iii, 393. Cyprid^e (pars), Baird, Trans. Berw. Nat. Club, ii, 153. Character . — Two pairs of antennae ; superior long, with numerous joints, and a pencil of long filaments ; inferior stout and pediform. Eye single. Feet two pairs. Bibliographical History . — 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 Muller. Linnaeus, in his ‘Fauna Suecica,’ 1746, describes a species in a few general terms; and, in the seventh edition of the ‘ Systemae 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 Gemuths- 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 GrBecensis,’ 1761, gives one species, the Monoc. conchaceus of Linnaeus, quoting merely his description. Geoffroy, 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. Muller, 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 Entomologiae,’ 1775, gives Linnaeus’s species, the Monoculus conchaceus; and l)e Geer, in his ‘Memoires pour servir a l’Histoire 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 Muller, with copious details and descriptions, and pretty accurate figures of all the species already shortly noticed in his * Zool. l)an. 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 Muller undertook the working out cyprim;. 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 Muller, 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 conchaceus of Linnaeus, with the description which that author gives in his 'Fauna Suecica,’ “Antennis 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 wrell as from his description, it appears to me that it bears a much closer resemblance to Muller’s Can- dida ; and the reference to He Geer is equally faulty, as it is evident that fig. 5, and figs. 6, 7, both of which are quoted by Muller as th spubera, are in reality two distinct species ! In determining the species, therefore, we must consider the researches of the various authors previous to Muller as of little or no use whatever. Indeed, after Muller’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 Muller’s species, but gives his erroneous references also, adding one or two of his own. He gives, however, two additional species, which Muller 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 eEnt. Syst.,’ 1793, gives the eleven species, which Muller describes, retaining, in addition to this, Gmelin’s erroneous synonyms. 142 BRITISH ENTOMOSTRACA. Bose, in his * Hist. Nat. cles 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. Button, par Sonnini, 1802 ; but they only mention Muller’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 Cypris strigata of Muller; 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 c 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 , anatomical description of the genus, with a notice, and figures of three new species, not described by Muller. About the same period as Straus read his paper before the Academy, appeared Jurine’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. * Beyt. zur Naturg. Deuts. Monoc. Arten, 1805. CYPRIDiE. 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 1 835 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 Philadelphia5 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. Muller has taken notice of them in the pub era, 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. la) 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 antennae, 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. 1$). In general they consist of seven articulations,* from the * Jurine says eight. CYPRIM1. 145 three or four terminating ones of which arise several 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 theim to and fro with great rapidity. They are thus considered by Muller 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 antennae : 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 antennae of the (Jydopidae, 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 * Jurine 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 which they live, 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 antennae, and is fixed to the body by four long apophyses. The inferior lip is elongated, triangular, and moveable ; 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 setae. The first joint has near its base a very small branchial plate terminated by five digitations. This palpiform part of the mandible is the second pair of feet of Jurine, the barbillon of Muller ; the use of which, 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 e) 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. 1 e*), which gives off from the superior crescentic-shaped edge a row of nineteen long spines, arranged like the teeth of CYPRIDJE. 147 a 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. 1 /). 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. Muller 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 h) 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 Muller 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 Muller, Ramdohr, and Straus, Jurine considers the organs which Muller 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. X Straus says five. 148 BRITISH ENTOMOSTRACA. They are 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 hooks, 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 by an anus between the two stylets which form the tail. The ovaries are two large, simple, conical vessels, 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 by the tail or abdomen. There is another 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 exactly 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 family are all inhabitants * Jurine considers them as somewhat connected with the matrix, but says he is ignorant of their use. The figure which he gives of them is very incorrect. CYPHIDiE. 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 Cyclopidse, 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 Ledermuller, 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 Ledermuller, but it did not appear to me that they were at the time engaged in copulation ; and as neither Muller , De Geer, Jurine, nor Straus have ever witnessed them in the act, Ledermuller 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 theDaphniadse, too, appear only at particular seasons of the year, and in small numbers, it is probable that the males of the Cypridse 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 BRITISH ENTOMOSTRACA. 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 Jurine they undergo several moultings before they are 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 branchiae, and the minutest hairs clothing the setae of the antennae, &c. The food of these little creatures consists of dead animal matter, Confervae, &c. Straus says he never saw them attack living animals when they were well 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 I have often observed indivi- duals of one species devouring eagerly the dead carcases of species different 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 when the rain falls and again overflows their habita- tions. After long-continued drought, however, 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 seem 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, “they” to use the words of Muller, “ 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 antennae provided with a pencil of long hairs or filaments. Animal swim- ming freely in the water. 2. Candona. — Inferior or pediform antennae destitute of the pencil of long hairs or filaments. Animal creeping on the ground or upon plants. Genus 1 — Cypris. ^ < Cypkis, Muller , Latreille, M. Edwards , Dana, fyc. Monoctjltjs, Linnceus, 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 ENTOMOSTRACA. 1. Cypris tristriata. Tab. XVIII, figs. 1, 1 a-i; 2, 3. Cypeis teisteiata, Baird, Trans. Berw. Nat. Club, i, 99, t. 3, f. 13, 1835 ; and ii, 152. Cypeis pubeea, Baird, Mag. Zool. and Bot., i, 524, t. 16, 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. Hab . — Berwickshire ; near London, &c. ; not un- common, all the summer months. - 2. Cypris vidua. Tab. XIX, figs. 10, 11. Cypeis vidua, Muller, Zool. Dan. Prod., No. 2384, 1776 ; Entomos- traca, 55, t. 4. f. 7-9. Latreille, Hist. Nat. Crust., iv, 245. Bose, Man. d’Hist. Nat. Crust., ii, 297. JDesmarest, 385, t. 55, f. 4. Baird, Mag. Zool. and Bot., i, 133, t. 5, f. 1 ; Trans. Berw. Nat. Club, ii, 152. M. Edwards, Hist. Nat. Crust., iii, 399, t. 36, f. 4. Monoculus viduus, Gmelin, Linn. Syst. Nat., 3002, No. 42. Manuel, Enc. meth., vii, 726, No. 36, t. 264, f. 24-26. Jurine, Hist. Nat. Monoc., 175, 1. 19, f. 5, 6. Bees , Cyclopaedia, art. Monoculus. Monoculus viduatus, Fabricius , Ent. Syst., ii, 496. Shell of an oval form, a little sinuated on under margin, CYPRIS. 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 fasciae, 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.* Hob. — Neighbourhood of London, Rugby, &c. &c. ; common during the summer months. — 3. Cypris monacha. Tab. XVIII, fig. 6. Cypris monacha, Muller , Zool. Dan. Prod., No. 2390, 1776; Ento- mostraca, 60, t. 5, f. 6-8. latreille , Hist. Nat. Crust., iv, 247. Bose , 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. M. Edwards, iii, 397. Koch, Deutsch. Crustac., h. ii, t. 1. Monoculus monachus, Gmelin, Linn. Syst. Nat., 3003, No. 44. Manuel, Enc. meth., vii, 727, No. 41, t. 266, f. 34-36. Fabricius, Ent. Syst., ii, 497. Bees, Cyclopsed., art. Monoc. Jurine, Hist. Nat. Monoc., 173, t. 18,f.l3, 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 Muller 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 Jurine. Muller’s figure represents the anterior extremity as the narrower. ft/ - . 154 BRITISH ENTOMOSTRACA. Hab . — Neighbourhood of London, July, August, and September. Old canal at Rugby ; Newnham Loch, Northumberland, Dr. Johnston.— 4. Cypris eusca. Tab. XIX, fig. 7. Cypkis ftjsca, Straus , Mem. Mus. Hist. Nat., vii, t. 1, f. 16, 1821. — Desmarest, Consid. gen. et part. Crust., 381. — M. Edwards, Hist. Nat. Crust., iii, 101, t. 36, f. 3. — Baird, Mag. Zool. and Bot., i, 1 31, t. 5, f. 1 ; Trans. Berw. Nat. Club, ii, 152. — Guerin, Iconog. Regne An. Crust., t. 32, f. 1. 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- tennae only three in number, and rather short. Hab . — Neighbourhood of London; Hampstead, &c., June, July, and August.- / Cyclops, Muller , Ramdohr, Latreille , Desmarest , &c. Cyclopsina {pars), M. Fdwards. Canthocampus, Westwood, Partington’s Cyclop. Nat. Hist. art. Cyclops ; The Entomologist’s Text-Book, 115. Canthocarptjs ( wrongly quoted), Baird, Trans. Berw. Nat. Club, i, 97, and ii, 154; Mag. Zool. and Bot., i, 326. Harpactictjs {pars), Dana, Proc. Amer. Acad. Arts and Sc., 1847. Nauplius, Fhilippi, Ann. Mag. Nat. Hist., 1840 ; Wiegm. Archiv, 1843. Character . — Foot-jaws small, simple. Antennules simple. Ovary single, f 1. Canthocamptus minutus. Tab. XXV, figs. 4-8; XXX, fig. 3. Cyclops minutus, Muller , Zool. Dan. Prod., No. 2409, 1776; Entomostraca, 101, t. 17, f. 1-7. — Ramdohr, Beyt. zur Naturg., 10-13, t. 3, f. 1-9. — Latreille, Hist. Nat. Crust., iv. 265. — Bose, Mem. Hist. Nat. Crust., ii, 25 7. — Lamarck, Hist. An. s. Yert., v, 189. * Erom aicavQa, a spine ; and KafnrroQ, flexible. f M. Edwards includes the Cyclops minutus of Muller in his genus Cyclopsina. The antennules, however, are not branched (biramees) as they are in Cyclops Castor , which is the character upon which the genus Cyclop- sina is founded ; and therefore it must form a separate genus. The name Canthocamptus was proposed for it by Mr. Westwood, some years ago, from the flexible, horny appendage attached to the abdomen of the female. In Partington’s Cyclopaedia, art. Cyclops, and in the ‘Entomologist’s Text- Book,’ this genus is indicated by Mr. Westwood, but misprinted Cantho- campus ; and it was farther misnamed by myself (quoting it from memory) in the ‘Trans. Berw. Nat. Club,’ i, Canthocarpus ; reproduced again in the ‘ Mag. Zool. and Botany,’ and in the second vol. of the ‘ Berw. Club Trans/ Philippi, in the Archiv, of Wiegmann and Erich sen for 1843, confirms my observations upon the structure of the antennules, and the propriety of separating the species from the genus Cyclopsina of Edwards. He forms of it, and some other species allied to it, the genus Nauplius. As that name was used by Muller for the young of the genus Cyclops, and as the genus Canthocamptus was shortly characterised by Mr. Westwood in the work quoted above as early as 1836, I have given the preference to Mr. West- wood’s appellation, as having the priority in date. Philippi, moreover, in- cludes the genus Harpadicus in his Nauplius. CANTHOCAMPTTJS. 205 Cyclops minutus, j Baird, Trans. 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, Gmelin, Linn. Syst. Nat., edit. 13th, i, 2997, No. 11. — Fabricius , Ent. Syst., ii, 499, No. 45. — Manuel , Encyc. meth., vii, 719, t. 267, f. 2-6. Monoculus staphylinus, Jurme, Hist. Nat. Monoc., 74-84, t. 7, f. 1-19, 1820. Cyclops staphylinus, Desmarest, 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. Fichhorn, Beyt. zur Naturg., 53, t. 5, f. k, l (adult) ; t. 3, f. p (young). Philos. Trans., No. 288. Naturforscher, Stuck vii, 101. Amymone satyra and baccha, &c., Muller , Entomost.,42, t. 2 (young) . Deb Satyr, Kohlers, Naturforscher, x, 103, t. 2, f. 10 (young). — Pritchard, Micros. Cab., t. 8, f. 2. Cyclopsina staphylinus, M.Fdwards, Hist. Nat. Crust., iii, 428. Canthocarpus staphylinus, Baird, Trans. Berw. Nat. Club, ii, 154, 1843. Nauplius minutus, Philippi, Wiegra. and Erichs. Archiv, 1843, p. 69. Doris minuta, Koch, 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 staphylinus from this circum- stance, objecting to the name of minutus , by which Muller originally designated it, as, he says, we may possibly find still smaller species. I have, however, retained the name which Muller 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 ENTOMOSTRACA. 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 antennae have the swelling and hinge- joint, the swelling existing chiefly about 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 3), and com- posed of two articulations. Upon the first is placed a small shoot, terminated by four setae, while the second is furnished with seven short spines on its upper edge, and terminated by four larger ones. Jurine 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 Cyclops quadricornis ; the palpiform branch springing from the centre, and consisting of three articulations, terminated by several setae. The anterior or first pair of foot-jaws (f. 5 e ) 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 setae. The posterior or second pair of foot-jaws (f. 5 d) are of very simple organization. They are formed of three articulations, the last of whieh 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 five pairs in number, and are much longer in proportion than in the preceding genus, and differ 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 g, Ji) 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 setae 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 antennae 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 BRITISH ENTOMOSTRACA. 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. Hah. — Ponds and ditches of fresh w^ater, all the year round ; common. 2. Canthocamptus Stromii. Tab. XXVII, fig. 3, 3 a. Cyclops Stromii, Baird, Zool. and Bot., i, 330, t. 9, f. 23-25, 1837. Cyclops brevicornis, Baird, Trans. Berw. Nat. Club, i, 97, 1835. Canthocarpus Stromii, Baird, Trans. Berw. Nat. Club, ii, 154, 1815. Nauplius Stromii, Philippi, Wiegm. and Erichs. Archiv,1843, p. 69. 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 two 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 are as in the preceding species. Each of the articulations of the antennae throws forward one or two short setae. The antennules are formed of two articulations, the second being 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 two 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. minutus. 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 setae; 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 Midler, wTho professes to take the species from Strom, in the ‘ Acta Hafniae,’ * 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 caudae lonyissimis” I gave it the name of Cyclops Strornii, f 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. * Yol. ix, p. 590. f Mag. Zool. and Botany, i, 330. 14 210 BRITISH ENTOMOSTRACA. 3. Canthocamptus 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. Edwards , Hist. Nat. Crust., iii, 429. Cantho carpus furcatus, Baird, Trans. Berw. Nat. Club, ii, 154, 1845. Nauplius furcatus, Philippi, Wiegm. and Erichs. Arcliiv, 1843, 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 antennae 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 antennules 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. minutus. 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 and terminated by two tolerably long and straight setae and five or six curved ones, each gradually be- coming shorter than the others. The three succeeding pairs of legs resemble those of the two preceding species. The fifth pair (t. XXX, f. 5 b) 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. 1844, Henry Hyde Salter, Esq.*~ 4. Canthocamptus minuticoenxs. Tab. XXV, fig. 3. — Cyclops minuticoenis, Muller , Entoraost., 117, 1. 19, f. 11, 15, 1781. — latreille , Hist. Nat. Crust., iv, 267. — Bose , Man. Hist. Nat. Crust., ii, 267. — Baird , Trans. Berw. Nat. Club, i, 97. Monoculus minuticoenis, Manuel, Enc. meth., vii, 720, t. 264, f. 21, 22. — Gmelin, Linn. Syst. Nat., edit. 13th, i, 2998, No. 17. Cyclops ineemis, Tilesius, Mem. de l’Acad. de St. Petersb.,v.t.8,f.9. Ca.nthocae.ptjs minuticoenis, 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 antennse 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 ENTOMOSTRACA. into eight very short articulations, having between the fourth and fifth a very small lateral joint, as in most of the other species. Each articulation sends off one or more setae. The antennules are similar to these organs in the other species, as are also the posterior foot-jaws, which consist of two rounded joints, terminated by a slightly- curved hook. The first pair of feet does 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 setae, as in the preceding species. Hab. — Berwick Bay, 1835. Dover, North Foreland, September 1849. Genus 3 — Arpacticus.* Cyclops, Muller, Tilesius, Baird, fyc. Monoculus, Manuel, Gmelin, fyc. Arpacticus, M. Edwards , Baird, Dana (in part). Nauplius (pars), Philippi. Character — Foot-jaws forming strong cheliform hands. Antennules simple. Ovary single. 1 . Arpacticus chelifer. Tab. XXIX, figs. 2, 3, 3 a-g . Cyclops chelifer, Muller, Zool. Dan. Prod., No. 2413, 1776; Entomost., 114, t. 19, f. 1-3. — Latreille, Hist. Nat. Crust., iv, 269. — Bose, Man, Hist. Nat. Crust., ii, 259. — Baird, Mag. Zool. and Bot., i, 328, t. 9, f. 15-22. Monoctjlus chelieer, Manuel, Enc. meth., vii, 721, t. 264, f. 32-34. — Gmelin, Linn. Syst. Nat., edit. 13th, i, 2998, No. 21. Cyclops Johnstoni, Baird, Trans. Berw. Nat. Club, i. 97, t. 2, f. 4, 1835. Cyclops armatus, Tilesius, Mem. Acad. Imp. St. Petersb., v, 366, t. 8, f. 7, 8. Arpacticus chelieer, Baird, Trans. Berw. Nat. Club, ii, 154, 1845. Nauplius chelifer, Philippi, Wiegm . and Erichs. Archiv, 1843, p.69. * From ap7ra%, rapacious. 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, having a short conical elongation in the centre. The antennae (f. 3 a) 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 ring, 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 setae, 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 Canthocamptus 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 clielifer of Muller, 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 c Transactions/ I was induced to make a distinct species of it, and named it Cyclops Johnstoni . Upon more minute examination, however, I have become satisfied that, notwithstanding these discrepancies, it approaches sufficiently near the C. clielifer to be identified with it. In describing this species, Muller says there are no articulations in the body, but that in form it is “ farciminis facie/’* He figures, too, only three articulations to the antennse. 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 of feet, 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 chelifer of Muller. Hab. — Sea-shore of Berwickshire, Cockburnspath, Ber- wick Bay, &c. ; common. Hover, North Foreland, Sep- tember 1849. v, 2. Arpacticus nobilis. Tab. XXVIII, figs. 2, 2 a-e. Arpacticus nobilis, Baird, Trans. Berw. Nat. Club, ii, 155, 1845 ; Ann. and Mag. Nat. Hist., xvii, 416, t. 9, f. 5, 5 a , b, c, d. The thoracic and abdominal portions of the body are * TilesiuS describes his C. armatus as having the articulations of the body very indistinct, and uses the same expression, “farciminis facie/’ He alludes to the C. chelifer of Muller as 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. The4, 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 setae with which they and the fulcra are provided being all 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. Hab. — Along with preceding in Berwick Bay, 1835. Dover, North Foreland, September 1849. 216 BRITISH ENTOMOSTRACA. Genus 4 — Alteutha.* Cyclops, Baird, Mag. Zool. and Bot., i, 1837. Alteutha, Baird, Trans. Berw. Nat. Club, ii, 155, 1815 ; Ann. and Mag. Nat. Hist., xvii, 416. Character . — Foot- jaws small, simple ; body flat. Two strong falciform appendages from the fifth segment of the body. Cyclops depressus, Baird, Mag. Zool. and Bot., 331, t. 10, f. 9-12, 1837. Alteutha depressa, Baird, Trans. Berw. Nat. Club, ii, 155, 1845 ; 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 body ; the terminating seg- ment 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 antennae are short, strong, subcylindrical, setiferous, and divided into six or seven articulations ; the first three of which are the largest, the last four 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,” the Town of the Tweed. 1. Alteutha depressa. Tab. XXX, figs. I, 2 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 Canthocamptus. 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. \b), 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/br- ward 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 surface of the 218 BRITISH ENTOMOSTRACA. water. For this purpose it curls its body into the form of a ball, and then suddenly returning to the straight position, springs with a sudden bound from the bottom to the surface, falling gradually down again to the same place from which it had sprung. Hah. — Berwick Bay, 1885, not common. — /^c^rr Family 2— DIAPTOMIM. Character. — Head in general distinguishable from the body, though firmly articulated with the first ring of the thorax. Foot-jaws, three pairs, well developed. Legs, five pairs ; the last pair differing in structure from the others, and differing also from each other in the two sexes. One eye; sometimes in male sex pedunculated. Bight antennae alone, in the male, furnished with the swollen hinge-joint. The habits and manners of the animals of this family are very similar to those of the Cyclopidse. Some are inhabitants of the fresh water, and others are marine. The manner of hatching their young, and the changes 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 with her, till the young are hatched, whilst, in the Cyclopidae, the eggs may be hatched, after they are removed from the mother. This family contains three British genera. 1. Diaptomus. — Flead distinguishable from body. Thorax and abdomen each composed of five segments. Antennules two-branched. 2. Temora. — Head consolidated with first ring of thorax. Thorax composed of five, and abdomen of three segments. Antennules two-branched. 3. Anomalocera. — Head distinguishable from body. Thorax composed of six, abdomen of four segments. Antennules not two-branched. DIAPTOMUS. 219 Gems 1 — Diaptomus. * Monoculus, Linnaeus , Fabricius, Jurine , 8fc. Cyclops, Muller , Lesmarest, Manuel, Sfc. Diaptomus, J. 0. Westwood, Partington’s Cyclopsed. Nat. Hist., art. Cyclops, 1836 ; Entomologist’s Text-Book, 1838. Omethia, Templeton, Trans. Ent. Soc., ii, 118, 1838. Cyclopsina,! M. Fdwards, 1840. — Philippi, Wiegm. and Erichs. Arckiv, 1843. — Baird, Zoologist, i, 56 ; Trans. Berw. Nat. Club, ii, 154. — Lana, 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. Diaptomus Castor. Tab. XXVI, figs. 1, 2, 2 a-j. Monoculus Castor, Jurine, Hist. Nat. Monoc., 50-73, t. 4-6, 1820. Cyclops Castor, Lesmarest, Cons, gen., 363, t. 53, f. 5, 1825. — Baird, Mag. Zool. and Bot., 324, t. 10, f. 1-8. Cyclops c^ruleus, Muller, Zool. Dan. Prod., No. 2411, 1776; Entomost., 102, t. 15, f. 1-9. — Latreille, Hist. Nat. Crust., iv, 265. — Bose, Man. Hist. Nat. Crust., ii, 257. Monoculus casruleus, Fabricius, System. Entomolog., 295. — Manuel, Enc. meth., t. 264, f. 1-9. — Gmelin, Linn. Syst. Nat., 2997, No. 12, edit. 13th. * Erom dia, through ; and nTrapai , to fly. f Though the genus Cyclopsina 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 ENTOMOSTRACA. Cyclops lacinulatus, Muller , Zool. Dan. Prod., No. 2410, 1776 ; Entomost. 105, t. 16, f. 4-6. — Ramdohr , Beyt. zur Naturg., 7-9, t. 2, f. 4-12. — latreille , Hist. Nat. Crust., iv, 266. — Bose, Man. Hist. Nat. Crust., ii, 258. — Baird, Trans. Berw. Nat. Club, i, 97. Monoculus lacinulatus, Manuel, Enc. meth., t. 264, f. 15-17. — Gmelin, Linn. Syst. Nat., 2997, No. 14. Cyclops rubens, Muller, Entomost., 104, t. 16, f. 1-3, 1781. — Latreille, Hist. Nat. Crust., iv, 266. — Bose, Man, Hist. Nat. Crust., ii, 258. — Baird, Trans. Berw. Nat. Club, i, 97, t. 2, f. 2 (the young). Monoculus rubens, Fabricius, op. cit. — Manuel, Enc. meth., t. 264, f. 10, 11. — Gmelin , Linn. Syst. Nat., i, 2997, No. 13. Diaptomus Castor, Westwood, Partington’s Cyclop. Nat. Hist., art. Cyclops, 1836. Disptomus Castor Baird {misprint'), Trans. Berw. Nat. Club, i, 97, 1835 ; Philosophical Transactions, No. 288, 1703, f. 6 of accompanying plate. — Baker, Microsc. made Easy, 93, t. 9, f. 2. Cyclopsina Castor, M. Fdwards, Hist. Nat. Crust., iii, 427,1840. — Baird, Trans. Berw. Nat. Club, ii, 154, 1845. Glaucea rubens, Koch, Deutsch. Crust., h. xxxv, t. 4 (male), t. 5 (female). Glaucea c^erulea, Koch, 1. c., xxxv, t. 6. Description. — The 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, the last being divided at extremity into two lobes, each of which gives origin to five plumose setae. 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 antennae are large organs, of great length, and strong. They are formed of about twenty-six articulations, each furnished with one or more setae, 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 Cyclopidse. The antennules (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 b) 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 BRITISH ENTOMOSTRACA. the upper edge of the centre plate. The second pair (f. 2 e) is flat and stout, composed each of a body which is indistinctly divided into three segments. The anterior edge is prominently marked with several eminences, from each of which spring two rather long setae, directed towards the mouth. 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 five. The legs are five pairs in number, and the first four, as in the Cyclopidae, are double. The basal portion consists of two articulations. In the first pair (f. 2 g) the external branch consists of three joints, and the internal of two. In the three succeeding pairs (f. 2 h) each of the branches is composed of three segments, and all are furnished with plumose setae. The fifth pair is differently formed from the others, and is strong and well-developed compared with that of the Cyclopidae. 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 j) the right branch is very much the larger of the two, 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 are called, by Jurine, the “ fulcra, or supports of the external ovary.” The dorsal vessel, or heart, is very distinctly to be seen under the second and third segment of the body. It is oval, and gives origin to two vessels of equal size, one going to the head, and the other to the abdomen, and has another organ attached to it, which is called by Jurine DIAPTOMUS. 228 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 operculum vulva. 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 vulvse, 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 Muller, and are called by him the lacinice. 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 lacinulatus. 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 Midler, 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. 224 BRITISH ENTOMOSTRACA. M. Siebold,* however, has had opportunities of studying them carefully, and the results of his observations, with his 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 fifth 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 is accomplished we see one fastened to her, near the vulva. If a male be examined, when in heat and before copulation take * Mem. de la Soc. des Scrutateurs de la Nature, de Dantzig, iii, part ii, 1839 ; Ann. des Sc. Nat., 2d ser., xiv, 20-38, 1840. f Ann. des Sc. Nat., xiv, 28. 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 zoosperms 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 15 226 BRITISH ENTOMOSTRACA. 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 the second substance, or the zoosperms, also. As soon as the glutinous matter touches the water, it coagulates, and as it continues to flow out, it leaves a canal in the centre of the 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 appears — 1st. That the male does not accomplish a true coition. 2dly. He attaches to the female, during copulation, a tube filled with spermatic liquor. 3d. This spermatic tube contains, be- side the zoosperms, two substances, of which one (the 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 the water, leaving in the middle of the mass a canal, by which the zoosperms arrive at the vulva. 4th. The zoosperms, situated in the neighbourhood of the vulva, penetrate in a manner as yet unknown beneath the operculum vulvse, and pro- bably in this manner fecundate the eggs, which some time later quit the sexual opening of the female. 5th. One and the same female is often covered with spermatic tubes at short intervals by different males. 6th. One and the same male appears able to furnish more than one single tube from its single sexual organ.” These observations of M. Siebold are very curious and highly interesting ; they appear to have been made with much care : but I am not aware of their having ever been confirmed by any succeeding naturalist. Jurine distinctly and with truth asserts, that the three species which Muller makes, the Cyclops caruleus , rubens , * Loc. cit., p. 37. TEMORA. 227 and lacinulatus , 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 Monocuius Castor . The cceruleus and rubens 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 blue 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 : “ Son port,” writes Jurine, “ est elegant ; sa maniere de s’elancer dans la liquide est noble et hardie ; ses mouvements sont libres et faciles ; tout enfin annonce chez lui une superiorite qui caracterise la grandeur de Tespece 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.- Gems 2 — Temora. f Monoculus, Gunner, Fabricius, Manuel, Gmelin. Cyclops, Muller , Latreille, Lamarck, Bose, Leach, Edin. Enc. Calanus, 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. Antennules 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. 228 BRITISH ENTOMOSTRACA. 1. Temora Tinmarchica. Tab. XXVIII, figs. 1, 1 a-g . Monocultjs Einmarchicus, Gunner , Act. Hafn., x, 175, f. 20-23, 17 65. Cyclops Finmarchicus, Muller, Zool. Dan. Prod., No. 2415. Cyclops longicornis, Muller, Entomost., 115, t. 19, f. 7-9. — Lamarck, An. s. Yert., v, 189. — Latreille, Hist. Nat. Crust., iii, 266 ; Gen. Crust, et Insect., ii, 26. — Bose, Man. d’Hist. Nat. Crust., ii, 259. — Leach, Edinb. Enc., art. Crustaceology. Monoculus longicornis, Fabricius, Ent. Syst., ii, 501, No. 52. — Gmelin, Linn. Syst. Nat., 2997, No. 15. — Manuel, Enc. meth., 720, t. 264, f. 11-14. Calanus Einmarchianus, Leach, Diet. Sc. Nat., xiv, art. Entomost. — Desmarest, Cons. gen. Crust., 364. — • Krusensterri? s Yoyage, Atlas, t. 22, f. 14. Description. — The body is of a dark brown colour (preserved 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 sefse, serrated on the edges. The antennae or rami (t. XXVIII, f. 1 /) 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 antennules (f. 1 b) 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 six articulations, the first and last of which are of equal length, and the four intervening ones are very short. The first joint gives off from its inner edge four long setae, 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 palpiform branch (f. 1 a) are ANOMALOCERA. 229 well developed, and, as well as the three pairs of foot-jaws (f. 1 c, d , e), exactly resemble those of Diaptomus. The four anterior pairs of feet (f. 1 g) 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. Genus 3 — Anomalocera.* Anomalocera, Templeton , Trans. Ent. Soc., ii, 35, 1837. Iren.etts, Goodsir , Edin. New Phil. Journ., xxxv, 339, 1843. Pontia, Baird , Trans. 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 Patersonii, Templeton, Trans. Ent. Soc., ii, 35, t. 5, f. 1-3. Pontia Patersonii, Baird , Trans. Berw. Nat. Club, ii, 156. Iren^eus splendidus, Goodsir , Edin. New Phil. Journ., xxxv, 339, t. 6, f. 12-17, t. 4, 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, * Prom avMjiaXoc, dissimilar; and Ktpag, a horn. 230 BRITISH ENTOMOSTRACA. sharp-pointed beak (t. XXVII, f. f. 2 a, b ) 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. Antennae long, 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 setae. 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 antennules (f. 1 ci) consist of a single branch, which is divided into three joints, the terminal joint being broad, and furnished with several long setae. The basal joint sends off from its internal side a small, slender twig, which is provided at the extremity with three or four setae. 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 b) is in form of a strong plate, fur- nished with five stout teeth on its internal extremity, and having a rather large, palpiform branch from its upper edge, divided into two smaller branches. Each of these is formed of two articulations, the terminal one giving off at its extremity several long, plumose setse. The jaws are only rudimentary organs. The foot-jaws are three pairs in number. The first * Goodsir, loc. cit., 339. “The peduncle of the eye is of a dark blue.” — Paterson, quoted by Templeton, loc. cit. t Ibid, ibid. ANOMALOCERA. 231 pair (f. 1 c) is of moderate size, each composed of a stout basilar joint or plate, which at its extremity gives off 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, which 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 setae of considerable length. The third pair (f. 1 e) 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 h) 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. I i) is large, composed of two stalks, both of which 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, each provided with five rather short and plumose setae. These bodies seem adapted for assisting the animal in swimming. Length of animal about three lines. 232 BRITISH ENTOMOSTRACA. From a careful examination of specimens sent me by Mr. Thompson, of Anomalocera Patersonii from Ireland, and Irenceus splendidus from Scotland, from an exami- nation of the specimens of Irenceus 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 are identically the same. The tubular organ in which the eye is situated in Irenseus, 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 Irenaeus seems to have been taken from a male specimen. He describes the little animal, when alive, as of a very 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 sapphirine and emerald.” “ The colour of the animal,” says Mr. Paterson, as quoted by Mr. Templeton, “ is a bright green, mottled with darker shadings ; the green colour is very fugacious, and observable only in recent specimens .... The first time,” he continues, “ on which I took any of these, was in crossing the ferry at the mouth of Larne 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 lively and constant motion, and jerk themselves out of the way when pursued. They form a portion of the food of a tentaculated Beroe.” (pp. 39, 40.) Hab. — Mouth of Larne Lough, county of Antrim, Mr. Templeton, W. Thompson, Esq. (Anomalocera) ; Frith of Forth, Mr. Goodsir; Kyles of Bute, W. Thompson, Esq. {Irenceus) ; Brit. Mus. CETOCHILUS. 233 Family 3— CETOCHILIDA3 * Pontiens, M. Edwards, Hist. Nat. Crust., iii, 412. Pontiadae, Baird, Trans. Berw. Nat. Club, ii, 155. Character . — Head 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 genus Cetochilus. Genus Cetochilus. f Roussel de Vauzeme , Ann. des Sc. Nat., 2d series, i, 333. M. Edwards, Hist. Nat. Crust., iii, 421. Goodsir, Edin. New Phil. Journ., xxxv, 339. Baird, Trans. Berw. Nat. Club, ii, 156. Character . — Head furnished with two small, styliform prolongations. Antennules 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 Cetochilida 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 ktjtoq , a whale ; and xiXoe, food. 234 BRITISH ENTOMOSTRACA. Tristan d’Acunha, in the South Atlantic, without his ever having been able to observe what formed the food of the whales. Leaving that quarter, however, at the end of that time, and steering for Cape Horn, he one morning, in the month of February, observed the surface 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 pasture 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, Yauzeme 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 wThole 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 wdiales swallowed them in myriads, and they served for food not only to them, but to the Cirrhopodes (the Coronulse and Tubicinellse), wjhich live as parasites upon their skin. The American fishers on that station informed him that these little creatures, in the fine weather of October and November, remain concealed deep under the water, but that after that time, they come to the surface to 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 Frith of Forth, Mr. Goodsir 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. Upon examining this matter, in the neighbourhood of the Isle of May, he found it to consist of Cirrhopodes, Crustaceans, and Acalepha ; but that of all these, the Entomostracous Crustaceans abounded in the greatest quantity, “ or rather masses,” he observes, * Edin. New Phil. Journ., xxxv, S8. 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 Cetacea 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-g. Goodsir, Edin. New Phil. Journ., xxxv, 339, t. 6, f. 1-11. Baird, Trans. Berw. Nat. Club, ii, 156. Description , — This 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. 236 BRITISH ENTOMOSTRACA. 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 setae; 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 palpiform branch arising from its upper surface, which is composed of two branches, 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 two other articulations, the last being very deeply notched, or lunate, instead of being cleft to the base, but all armed with long setae. The second (f. 1 e) is composed of two articu- lations, each of which is knobbed on its inner edge, and armed with twelve long, finely-plumose setae, those * Loc. cit. IsOTODELPHYS. 237 of lower joint arising in pairs. The third pair of foot- jaws (f. 1 /) 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 setae on the inner edge. The legs are five pairs, all formed alike. They con- sist (f. 1 g) 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. Hab. — Frith of Fortin IT. 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 Cyclopidae and Cetochilidae, 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 antennae 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 vojtoq, tergum, back ; and 8t\/, head. 296 BRITISH BN TO M 0 ST R A C A . We have only one British family belonging to this tribe. Family AN THO SOM AD.A3 . .Dichelestldje (pars), if. Edwards. CaligidyE, race i (pars), Leach, Diet. Sc. Nat. — Desmarest, Cons. 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 with strong hooks. Thorax furnished with elytraform appen- dages. Feet, three pairs ; all foliaceous. Genus Anthosoma. Anthosoma, Leach , Desmarest, Kroyer , if. Edwards, Burmeister, Latreille, 8fc. Caligus, Abildgaard, Risso, Lamarck. Otropresa, Risso, Hist. Nat. Eur. merid. 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 Caligus 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 genus a specimen taken from a shark on the coast of England. He first described it in the ‘ Encyclopsedia 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, Bisso described shortty, 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 Caligus imbricatus , 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 Otrojohesa 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 , 8fc. — 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 very indistinct. On 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 antennse, 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. ERGASILJDiE. 299 1. AnthosOxMa Smithii. Tab. XXXIII, fig. 9. Anthosoma Smithii, Leach , Enc. Brit. Supp., i, 406, t. 20, f. 1-6 ; Edirib. Encyclopsed., t. 181 ; Diet. Sc. Nat., xiv. 533. — Desmarest , Cons. gen. Crust., 335, t. 50, f. 3. — Latreille , Cuv. Begne Anim., iv, 198 ; Enc. meth., t. 335, f. 11-16. — Guerin . Icon. Cuv. Begne Anim., t. 35, f. 9. — Griffith , An. Kingd. Crust., t. 21, f. 2. — Kroner, Tidsskrift, ii. 295, t. 2, f. 2. — AT.i^imrflfc,Hist.Nat. Crust. ,iii, 483, t. 39,f.5; Cuv. Begne Anim., edit. Cro chart. Crust., t. 79, f. 3. Caligus Smithii, Lamarck , An. s. Vert., v. 210. Caligus imbricatus, Risso, Hist. Nat. Crust. Nice, 162, t. 3, f. 13. Otrophesa imbricata, Risso, Hist. Nat. Eur. merid., 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. Hab. — Discovered sticking to a shark (the Lamna cor- nubica) thrown ashore at Exmouth, Devonshire, by T. Smith, Esq., of the Temple, who sent it to Dr. Leach. British Museum. Eamily EBGASILID^. Ergasiliens, M. Edwards , Hist. Nat. Crust., iii, 476. NicothoidxE, 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. Eeet very small, and branched. Abdomen well developed. 300 BRITISH ENTOMOSTRACA. Genus Nicothoe.* Nicothoe, M. Edwards and Audouin, Ann. Sc. Nat., ix, 345. — M. Edwards , Hist. Nat. Crust., iii, 480. — latreille , Cuv. Regne Anim., 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. Toot-jaws very small. Thorax enlarged laterally into the form of two large, wing-shaped lobes. Eeet four pairs, two-branched, and jointed. Body articulated. Bibliographical History . — MM. Audouin and M. Edwards were the first who noticed the Nicothoe, and in their memoir, published in 1826 in the 4 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 Lerneadae. When reversed, and exhibiting their jointed antennae and articulated feet, they had a close resemblance to the Cyclopidae. “ 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 Lerneiformes, as coming next to the Lerneae. 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 c Nova Acta,' he has given us many details of the development of the young, * Nicothoa, one of the Harpies. NICOTHOE. 301 from the egg up towards maturity, of a highly interesting nature. Anatomy and Physiology , 8fc. — 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 articulation s^ 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 Cyclopidae, 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 sturionis, and Lernceojpoda stellata , 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 setae. 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, 1843. 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 no 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, aud the posterior, foot-jaws. A very curious circumstance has been observed by Rathke, with regard to the further development of these * Ann. Sc. Nat., ix. N1C0TH0E. 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 antennae 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, antennae, 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 Ergasilidse appear to connect the Cyclopidae with the Lerneadae ; but in habits and mode lerneaile. 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 Anim., 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. RathJce, 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. Hah. — On the gills of the common lobster. London market, March and April, 1849 ; W. B. Falmouth, Sept. 1849 ; W. P. Cocks, Esq. British Museum. Okdeb. II — LERNEADiE. 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 Lernese 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 cams exortu, habent enim utrique per id tempus sub pinna ceu vermiculum, quem asilum vocant, effigie scor- pionis, magnitudine aranei ; infestat hoc tanto dolore, ut non minus interdum gladius quam delphinus exiliat, unde fit, ut vel in navigia ssepenumero 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. f Athenseus 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 Athenseus.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 off 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, scorpionis effigie, aranei magnitudine. Hoc se, et thynno, et ei qui gladius vocatur, crebro delphini magnitudine excedenti, sub pinna affigit aculeo, tantique infestat dolore, ut in naves ssepenumero exiliant. Quod et alias faciunt aliorum vim timentes, mugiles maxime, tarn prsecipuse velocitatis, ut transversa navigia interim superjactent.” — Hist. Nat., lib. ix, cap. 16. f “ Dum canis ardenti turbatur sydere cadum Et thynni et gladii diro vexantur asilo : Qui fixus madidis illos contundit in alis. Non arcere queunt, non banc propellere pestem, Incutit hoc celeres vires, stimulosque feroces Concitat ; armantur rabie, furuentque dolore : Invitosque agitat pestis furibunda natantes : Exhorret vulnus, bacchantur in aequore lata. Hi torti stimulis incursant navibus altis : Et ssepe in terram saliunt e gurgite vasto. In tanto volvunt luctantu membra dolore, Et vitam in tanto mutant cum morte furore.” Alieuticon, traduct. Laurent. Lippio, liber xi, p. 24. § P. 249. \ Pp. 126-8. LERNEADiE. 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 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.! The speci- men he describes as having examined himself was, he says, of a white colour, and was found adhering “ ad piscem 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 olarrpog, or Asilus marinus of Aristotle, Pliny, Rondeletius, and Gesner, and nearly identical with the animal figured by Pernetty. Boccone, a Sicilian gentleman, in his ‘ 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 marinus 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 nihil est quod hoste careat” (p. 112), a remark well illustrated by the little fact just mentioned by Boccone. J Muraltus, in the e Miscellanea curiosa siveEphemeridum Medico Physicarum Germanicarum Academise Naturae Curiosorum/ published at Nuremberg in 1,682, mentions that while dissecting a specimen of the Mustela Jluviatilis , 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 * Pecherches et Observations, p. 284, et sequent, tab., p. 287. f This animal is a species of Penella, or Pennatula, Linn. 1 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 ad infinitum ! LERNEADiE. 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 Pediculus salmonis.\ In the ‘Syst. Nat.,* 12tli 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 Lerneae, 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 Hr. 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. f The Lerneonema monillaris, M. Edwards. X Act. Holmens., 1751, p. 181, t. 6, f. 1-5. § Loudon’s Magazine of Natural History, viii, 565. 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 Linnaeus, 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 cephales. Bose 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 Planariae 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 c Lehrbuch der Naturgeschichte/ following Linnaeus in placing the Lerneae amongst the Mollusca, was the first who commenced dividing them LERNEADA3. 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 RegneAnim.,’ without at the time being aware what Oken had previously done. In 1817 Cuvier adopted the view taken by Bose, 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 bizarre- looking 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 Erench 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 Caligidae, and traced the almost insensible gra- 314 BRITISH ENTOMOSTRACA. dations by which we are carried from that genus to the Caligns 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 Nicothoe,f and in the course of their observations upon the history of this curious Siphonostome they came to the conclusion, reasoning from analogy, that the Lerneee 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 Nit sch, 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 crustaceous. 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, c Mikrographische Beitrage zurNaturgeschichtederWirbellosenThiere/ 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 des Crustaces, p. 343, note. f See above, p. 300. ✓ LERNEADiE. 315 Burmeister ; * an Austrian naturalist, Vincenz Kollar ; f and the acute observer Rathke. \ 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 Lerneae would not have re- mained, as they now do, amongst his intestinal worms. In 1837 Kroyer published, in his 4 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 4 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 Lerneae after the time of Linnaeus; however, their number is considerable. Strom, in the ‘Phvsiske og Oeconomisk,’ 1762; Ellis, in the ‘ Philosoph. Trans.,’ liii; Eabricius, in the ‘ Fauna Groen- landica,’ 1780; Miiller, in the 4 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 4 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. Caesar. Nat. Cur., xvii, tli. i. f Annal. der Wiener Museums, i, abth. i. | Nov. Act. Nat. Cur., xx. 316 BRITISH EN TOM 0 STR A 0 A . f 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 Loudon’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, 8fc. — The form of the animals belonging to the Lerneadse is very variable. “ Respecting this,” says Kroyer,* £C 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. 174. LERNEADiE. 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 Lerneadse, 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 Siphonostoma 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- nostoma. The mouth, according toKroyer, 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 out 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, wThere 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 wduch 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 branchiae 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 — how 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 LEKNEADiE. 819 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 Lerneadse 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 Lerneadm 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 Cyclopidae. 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 Cyclopidse, 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~jawrs, 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 Lerneadse show, with the exception of taking food and laying eggs, very few and feeble signs of life, whether attached to the nourishing animal or when 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. branchialis ), 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.” LERNEAlUE. 321 That part of the history of the Lerneadse 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 Lerneadse, Nordmann discovered, in several instances, small bodies adhering to the generative organs of the females, which, on closer im 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, 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 Lerneadse 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 Anchorastomacea. CHONDRACANTHIDiE. 323 Tribe 1 — AN CHORASTOMA CEA. * Chondracanthiens, M. 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 antennae ; generally very distinct. Thoracic feet nearly rudimentary, or represented by appen- dages of considerable size, but differing in form from ordinary feet. Males. Tree and unattached ; very small and differing totally in appearance from the females. Family CHONDRACANTHIDiE. 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 f Wastogota Resa,’ or tour through Westrogotha in 1747, describes a species of Lernea, which he afterwards named Lerncea asellina , that evidently belongs to the family of Chondro- canthidae. 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. Muller, 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 - phcena rupestris. Delaroche, in the ‘ Nouv. Bull, des Sc. de la Soc. Philom./ 1811, describes another species, and * Ayicvpa, anchor ; and 7. Lern^ea, Cuvier, Begne An., iii, t. 15, f. 4. Character. — Female . Body somewhat square -shaped. * Not Lerneomyzon trigla, 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 Chondr acanthus (Lernentoma) cornutus. Hab. — It is found attached to the branchiae of the Triglce. Ealmouth, J. Crouch, Esq. British Museum. 3. Lernentoma Lophii. Tab. XXXV, fig. 3. Chondeacanthus Lophii, Johnston, , London’s Mag. Nat. Hist., ix, 81, 82, f. 1 Qa-c, 1836. — Rathke ,* Nov. Act. Nat. Cur., xx, 116, t. 5, f. 11-18, 1843. Chondbacanthus gibbosus, Kroyer , Tidsskrift, i, 252, t. 2, f. 4. Chondeacanthus Delaeochiana {pars), M. Edwards , Hist. Nat. Crust., iii. Character . — Femate. 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 used. ANCHORACARPACEA. 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. Hah. — Found on the Lophius piscatorius, 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. Tribe 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. * Ay/cvpa, anchor; and Kapnoc, arm. 332 BRITISH ENTOMOSTRACA. Males in general differ very much in appearance from the females, being greatly smaller and unattached. Family LERNEOPODADJE. 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. Phys., xcv, 442, 1822. — Kroyer, Tidsskrift, i, 207. — M. Edwards, Hist. Nat. Crust., iii, 514. — W. Thompson, Ann. Mag. Nat. Hist., xx, 248. — Rathke, Nov. Act., xix. Lernea, Gisler, Linnaeus, Grant, Retzius, 8fc. 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 “ Fedi - cuius salmonis or lax-lusen.” f Linnaeus, in his ‘Fauna Suecica/ 1761, describes this species as the Lerncea salmonea , and repeats it in his * Aepvaiog, belonging to Lernea ; and ttovq, foot, f “ Salmon louse.55 LERNEOPODA. 333 ' Syst. Nat./ 1766. The same little animal was a few years afterwards described as British ; the Rev. Charles 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 1827, under the name of Lerncea elongata . 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. XXXY, fig .5. Lerncea elongata. Grant , Brewster’s Edinburgh Journ. of Sc., vii, 147, t. 2, f. 5, 1827. Lerneopoda elongata, Kroyer , Tidsskrift, i, t. 2, f. 12, t. 3, f. 3 a. — M. Edwards, Hist. Nat. Crust., iii, 515. The Eye of the Greenland Shark, Scoresby, Arctic Regions, i, 538, t. 15, f. 5. Description . — The 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 the body 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. Hab. — A specimen of this arctic species was found at- tached to the eye of a shark caught on the English coast, and brought to London in the winter of 1848. Mr. Yarrell, to whom 1 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. Lerneopoda 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. Pedicultjs salmonis, OUler, Kongl. Svensk. Vetensk. Acad.Hadling., xii, 171, t. 8, f. 1-5, 1751. Lern.®a salmonea, Linnceus , Faun. Suec., edit. 2d, 509, No. 2102, 1761; Syst. Nat., edit. 12th, 293; Lernsea,No.3. — Cor diner, Antiq. and Seen, of the N. of Scotland, 7, 8, t. 6, f. 2. — 0. Fabricius , Faun. Grcenl., 337. — Muller , Zool. Dan. Prod., 2711. Entomoda salmonea, Lamarck, Hist. An. s. Vert., edit. 2d, iii, 686, Lerneopoda salmonea, Blainville, Journ. Phys., 1822, 127. — Mayor, Bull, des Sc. Soc. Philom., 1821, 21. Lerneopoda carpionis (?), Kroyer, Tidsskrift, i, t. 2, f. 6. — M. Fdwards, Hist. Nat. Crust., iii, 515, Linnaeus’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 pyriform 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. ^^<5. — -Gills of the salmon, London market, W. B. Family 2-ANCHORELLAD M. 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. Lernasa, Strom , Sondmoer ; Lamarck, Muller, Johnston. Anchorella, Cuvier, Regne An., 1817 ; Nordmann, Burmeister , Kroyer, M. Edwards. Clavella (pars), Oken, Lehrbuch, 1815 (not Cuvier, R egne An., nor Kroyer) . Lerneomyzon, Blainville , 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. Antennae 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 Lerneadae 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 Anchorella 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. XXXY, fig. 9. Lern^ea uncinata, Muller , Zool. Dan., i, t. 33, f. 2; Enc. meth., Yers, t. 78, f. 7 (copied from Muller). — Lamarck , An. s. Yert., edit. 1st, iii, 231. — Johnston, Loudon’s Mag. Nat. Hist., viii, 565, f. 53. — Thompson , Report on Fauna of Ireland, div. In- vertebrata, in Report of Brit. Ass., 1813, 270. — Fabricius , Faun. Greenland., 338, No. 328. — Turtords Gmelin, iv, 111. — Bose, Hist. Yers, i, 59, t. 1, f. 1. Schisturus uncinatus, Oken, Lehrbuch der Naturg., B, iii, p. 183. Clavella uncinata, Oken, 1. c. Lerneomyzon 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. Fdwards, Hist. Nat. Crust., iii, 519. Anchorella lagenula, Enc. Brit., edit. 7th, xxi, t. 502, f. 11. 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. Hab. — 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 1837; W. Thompson, Esq. In the latter specimen the ovaries are considerably longer than the thorax. 2. Anchorella rtjgosa. Tab. XXXV, fig. 8. Anchorella rtjgosa, Kroyer, Tidsskrift, i, 284, t. 2, f. 7. — M. Edwards, 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. Hab. — From the mouth of a Gadus cellarius , taken at Larne ; W. Thompson, Esq. Tribe III — ANCH ORA CERA CEA* Lerneoceriens (pars), M. Edivards , 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 antennae. Only one pair of foot-jaws, which is simple and hooked. Eeet either very small or often wanting altogether. * Ay Kvpa, anchor, and Kipag, 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 — PENELLADiE. 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, Turton’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 Lerneadae, 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 ENTOMOSTRACA. the Lerneae 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 Lerneonema spratta, 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 necJc 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 sawT 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 f 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 cyclojohora , 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. 341 1. Lerneonema spratta. Tab. XXXV, fig. 10. Lern^ea spratta, Sowerby, British Miscellany, t. 68, 1806. Lern.ea cyclophora, Blainville, Journ. de Phys.,xcv, t. 26, f. 7 ; 1822. Lerneide articulee, Blainville, 1. c., f. 17- Lerneonema monillaris, M. Edwards, Hist. Nat. Crust., iii, 525, t. 41, f. 5, 1840. — Thompson, Report Brit. Assoc, for Advance. Sc. 1843, 270. The Eye-sucker, Baker, Phil. Trans., xliii, 35, t. 1, f. 2, 3, 1744. 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. 2. Lerneonema encrasicoli. Tab. XXXV, fig. 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. Hab. — -Attached to the body of a sprat, from Youghal ; R. Ball, W. Thompson, Esq. “ Found attached to the bodies of the Clupea encrasicolus and spraitus frequently, in Swansea Bay W. Turton, M.D.. Attached to the body of a sprat ; Mr. J. Doubleday. British Museum. Family 2— LERNEOCERAE'iE. Lerneoceriens (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, Linnaeus, Barbut, Hermann, Lamarck . Lerneocera, Blainville, Journ. Phys., 1822. — Desmarest, Nordmann, Burmeister, 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 * Aepvnwg, belonging to Lernea, and ictpag, horn. LERNEOCERA. 343 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. Lern^ia cyprinacea, Linneeus, Faun. Suec., No. 2100, t. 2, f. 2100 ; Syst. Nat., edit. 12th. — Barbut , Gen. Vermium, t. 7, f. 3. — Turton, Brit. Faun., 137, No. 105. — Lamarck, An.-s. Vert., iii, 230; Enc. meth., Vers, t. 78, f. 6. Lerneocera cyprinacea, Blainville , Journ, de Phys., xcv, 3 77. — Desmarest , Cons. gen. Crust., 346. — Burmeister , Nov. Act. Nat. Cur., xvii, 309, t. 14 a, 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. Hah. — “ 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, Linnaeus, Muller, 0. Fabricius, Olcen , Cuvier , Lamarclc , Burmeister, Kroyer, M. Fdwards. Lerneocera, Blainville , Nordmann. 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 the 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 cyclojphora (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. Lernea branchialis, Linnaeus , Syst. Nat., edit. 12th. — Lamarck , An. s. Vert, iii, 240. — Cuvier , Regne An., iii, 256. — Burmeister , Nov. Act., xvii. — Guerin , Icon. "Regne An. Zooph., t. 9, f. 1 ; Encyc. Britann., edit. 7th, xxi, t. 502, f. 13. LERNEA. 345 Lernea branchialis, Kroner, Tidsskrift, i, t. 3, f. 10 (?). — Oken, Lebrbucli der Naturg., t. 7. — M. Edwards , Hist. Nat. Crust., iii, 528. — Thompson, Report Brit. Assoc, for Advanc. Sc, 1843, 270. Lernea gadina, Muller , Zool. Dan., iv, 65, t. 118, f. 4. — 0. Fabricius , Paun. Grcenl., 339. Lerneocera branchialis, Blainville , Journ. de Phys., xcv, 376, tab. 26, f. 1, 1 a. — Nordmann, Mikr. Beitr., ii, 130. IiERNiEA, Strom , Phys. og Oecon. 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. Hah. — 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 QUADRICORNIS. 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 setae 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 ce’ 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 in 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. Salter 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 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. I > Acanthocercus, 103. curvirostris, 103. Acroperus, 14, 123, 129. harpse, 129. nanus, 130. Alona, 14, 123, 131. ovata, 133. quadrangularis, 131. reticulata, 132. Alteutha, 14, 198, 216. depressa, 216. Amymone Baccha , 205. satyra , 205. Anclioracarpacea, 15, 331. Anchoraceracea, 15, 338. Anchorastomacea, 15, 323. Anchorella, 15, 336. lagenula , 337. rugosa, 338. uncinata, 337- Anchorelladse, 15, 336. Animaletti aquatici, 90. Anomalocera, 14, 218, 229. Patersonii, 229. Anops, 327. cor nut a, 328. Anthosoma, 15, 296. Smithii, 299. Anthosomadse, 15, 296. Apodidse, 14, 18. A n O Y S, 29. Apus, 14, 18, 29. cancriformis, 30. Montagui, 30. Argulidse, 15, 242. Arguliens, 242. Argulina , 242, Argulus, 15, 242. argulus , 255. charon, 255. delphinus, 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, 1 76. Bairdia , 163. siliqua, 171. Binoculus , 29, 242, 269. cauda biseta, 30. g aster ostei, 256. palustris , 30. piscinas, 276. Bitestaces , 138. - Bopyridce , 289. Bosmina, 14, 89, 105. cornuta , 105. longirostris, 105. Branchiopoda, 14, 17. Branchiopodes , 16. franges , 138. Geans, 17. Lamellipedes, 17. parasites , 240. Branchiopteres , 16. Branchipidce , 38. Branchipiens, 38. Branchipodidse, 14, 38. Branchipus, 39, 54. cancriformis , 30. chirocephalus , 53. conchiformis primus , 93. diaphanus, 53. paludosus, 53. Prevostii , 53. salinus , 61. stagnalis, 54. Branchipusidee, 38. Brine-worm , 61. 350 INDEX. Calanus , 227. Finmarchianus , 228. Caligacea, 240. Caligidee, 15, 256, 281, 289, 296. Caligina, 256. Caligus, 15, 268-9, 273, 286, 296. bicolor , 288. bicolor , var. 289. centrodonti, 272. diaphanus, 269. hippoglossi, 276. imbricates, 299. Mulleri, 271. Nordmannii , 275. peel oralis, 275. t rapax, 270. Smithii, 299. Stromii, 274. vespa, 274. Camptocercus, 14, 123, 128. macrourus, 128. Cancer, 36, 39, 54. bipes, 36. {Gammarellus) bipes, 36. paludosus, 54. salinus, 61. stagnalis, 54. Candona, 14, 151, 159. Candida, 160. detecta, 161. hispida, 161 . lucens, 160. v/- reptans, 160. similis, 162. CantJiocampus, 204. Canthocamptus, 14, 204. furcatus, 210. minutus, 204. minuticornis, 211. Stromii, 208. Canthocarpus, 204. furcatus, 210. minuticornis, 211. staphylinus, 205. Stromii, 208. Carcinoida, 182. Cecropidse, 15, 289. Cecropina, 289. Cecrops, 15, 289. Latreilleii, 293. Cephaloculus, 111. stag norum, 112. Cetochilidm, 14, 233. Cetochilus, 14, 233. Cetochilus septentrionalis, 235. Chalimus, 15, 268, 278. Scombri, 279. Chirocephalus, 14, 39. diaphanus, 53. Frevostii, 53. Chondracanthidse, 15, 323. Chondracanthiens, 323. Chondr acanthus, 15, 326-7. cornutus, 328. Delarochiana, 330. gibbosus, 330. Lophii, 330. triglae, 329. Zei, 327. Chydorus, 14, 123, 125. globosns, 127. Mulleri, 126. sphsericus, 126. Cladocera, 14, 62. Cladoceres, 62. Clavella , 336. uncinata, 33 7. Copepoda, 14, 182. Cormostomata , 240. Crophyropoda, 138, 182. Crust aces sessiliocles , 16. suceurs, 240. Cyclopace a, 182. Cyclopidse, 14, 183. Cyclopidees, 183. Cyclops, 14, 198, 204, 212, 216, 219, 227. Cyclops agilis, 202. armatus, 212. bistriatus , 203. brevicornis, 208. castor, 219. chelifer, 212. caruleus, 219. depressus, 216. Finmarchicus , 228. furcatus, 210. Geojfroyi, 199. mermis, 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. staphylinus, 205. Stromii , 208. vulgaris, 199-203. Cyclopsma , 201, 219. castor, 220. furcatus, 210. staphylinus, 205. Cyprella, 176. Cypridacea, 138. Cypridae, 139. Cyprididse, 14. Cypridina, 14, 163, 174, 176. Brenda, 181. Mac Andrei, 179. Cypridinadae, 176. Cypris, 14, 139, 151. aurantia, 159. Candida, 160. clavata, 157. compressa, 154. detecta, 161. elliptica, 158. elcmgata, 156. fusca, 154. gibbosa, 156. hispida, 161. Joanna, 155. lucens, 160. lucid a, 160. ininuta, 155. monacha, 153. nubilosa , 153. pellucida, 160. pubera , 152. punctata, 154. reptans , 160. sella, 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. aurantia, 171. convexa, 174. flavida, 168. Cytliere 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. Cytheridae, 162. Cytlierina, 163-74. Cytherinen, 162. Daphne, 89. crystallina, 107. mucronata, 99. pulex, 90. rectirostris, 101. vetula, 95. Daphnella, 14, 89, 109. Wingii, 109. Daphnia, 14, 62, 88, 89, 103, 105, 106. angulosa , 98. bispinosa, 99. brachiata, 102. crystallina, 107. curvirostris, 103. cornuta , 105. congener , 96. ephippiata, 90. exspinosa, 96. longispina, 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. rosea, 104. rotunda, 98. Schoefferi, 93. sima, 95. ventricosa, 97. INDEX. 352 Daphnia vetula, 95. Daphniadae, 14. Baphnina, 88, 89. Baphnidce, 115. Baphnides, 62, 115. Daphnidiens, 62, 115. Daphnoides , 62. Der Satyr, 205. Diaptomidae, 14, 218. Diaptomus, 14, 218, 219. Castor, 219. Bichelestidce, 296. Dinematura, 282. alata, 285. Dinemoura, 15, 281, 282. alata, 285. lamnae, 286. Binemura , 282. Bisptomus Castor, 220. Boris minuta, 205. Entomoda, 327, cor nut a, 328. salmonea, 335. Entomostraca, 14, 16. Ergasilidse, 15, 299. Ergasiliens, 299. Ergasilina, 296. Eunica, 105. longirostris, 105. Eurycercns, 14, 123. lamellatus, 124. Evadne, 14, 114. Nordmanni, 114. Eye of the Greenland Shari;, 333. Eye-sucker, 341. Fisch-laus, 256. Floss-fussigen seewurm, 30. Four-horned Cyclops, or small Water- flea, 199. Gammarus, 54. salinus , 61. Geschwanzten zaclciger Wasserfloh, 93. Glaucea carulea, 220. rubens, 220. Harpacticus, 204. Horned Lerncea, 328. Ino, 39. piscina, 54. Irenrsus, 229. splendidus, 229. Kiefenfuss, 30. Laxe-luus, 274. Laemargus, 15, 293. muricatus, 295. Le Monocle a quatre comes, 199. a queue fourchue, 198. a queue retroussee, 112. Le Per roquet d’eau, 90. Le Puceron verdatre, 91 . Lepeoptlieirus, 15, 268, 273. hippoglossi, 276. N ordmannii, 275. obscurus, 277. pectoralis, 275. Stromii, 274. Thompsoni, 278. Lernacantha, 326. Belarochiana, 327. Lernaa, 327, 329, 332, 336, 339, 342, 344. asellina, 329. cauda duplici tereti, 329. cor nut a, 328. cyclophora, 341. cyprinacea, 343. elongata , 333. encrasicoli, 341. gadina, 345. pectoralis , 275. salmonea, 335. spratta, 341. uncinata, 337, Lernea, 15, 344. branchialis, 344. LerneadaB, 15, 307. Lerneide articulee, 341. Lernentoma, 15, 327. asellina, 329. cornuta, 328. Lopliii, 330. trigla, 329. Lerneocera, 15, 339, 342, 344. branchialis, 345. cyprinacea, 343. Lerneoceradae, 15, 342. Lerneoceriens, 338, 339, 342. Lerneomyzon, 336. uncinata, 337. Lerneonema, 15, 339. encrasicoli, 341. monillaris , 341. spratta, 341. Lerneopenna, 339. INDEX. 353 Lerneopoda, 15, 332. carpionis, 335. elongata, 333. galei, 334. salmonea, 335. Lerneopodadae, 15, 332. Lerneopodiens , 331, 332, 336. Les Monocles , 16. Limulus, 29. cancriformis, 30. palustris , 30. Lophyropa , 138. Lophyropoda, 14, 138. Louse of the banstickle , 256. carp , 256. Lynceidse, 14, 115. Lynceus , 103, 105, 115, 123, 125, 128, 129, 131, 134, 136. hamatus, 136. harpce , 129. lamellatus , 124. laticornis, 103. leucocephalus , 129. longirostris, 105. macrourus, 128. quadrangularis, 131. roseus, 104. sphvericus, 126. trigonellus, 134. truncatus, 137. Macrothrix, 14, 88, 103. laticornis, 103. roseus, 104. Marteau d'eau douce, 54. Moina, 14, 88, 100. brachiata, 102. rectirostris, 101. Monocles a coquille bivalve, 151. Monoculus , 16, 17, 29, 30, 36, 89, 103, 105, 106, 111, 151, 183, 198, 204, 212, 219, 227, 242, 269. apus, 30, 198. argulus, 255. bispinosus , 99. bistrigatus, 157. brachiatus, 102. cceruleus , 219. castor , 219. cauda biseta, 30. cauda foliacea plana, 256. chelifer, 212. conchaceus, 96. j Monoculus cornutus, 105. crystallinus, 107. cyprinaceus, 256. delphinus, 255. detectus, 161. elongatus , 107. exspinosus , 96. Finmarchicus, 228. flavidus, 168. foliaceus, 255. gyrini, 255. infusorius, 126. lacinulatus , 220. Ivevis, 96. lamellatus, 124. laticornis, 103. longicornis, 228. longispinus, 91. macrourus, 128. minuticornis, 211. minutus, 205. monachus, 153. 'mucronatus, 99. nasutus, 96. oculus, 112. ovum, 155. pediculus, 111. pediculus ramosus. 111. polyphemus, 112. pulex, 89, 96. pulex arborescens , 90. pulex ramosus, 90. quadrangularis, 97, 131. quadrangulus, 131. quadricornis, 198. rectirostris, 101. reticulatus , 97. roseus, 104. rostratus, 96. rubens, 220. simus, 96. spluericus , 126. staphylinus, 205. striatus, 131. stngatus, 157. trigonellus , 134. truncatus, 137. viduatus, 152. viduus , 152. My sis, 36. Nauplius, 204, 212. chelifer, 212. furcatus , 210. 23 INDEX. 354 Nauplius minutus, 205. saltatorius, 199. Stromii, 208. Nebalia, 14, 31, 36. bipes, 36. ciliata, 36. glabra , 36. Herbstii , 36. Montagui , 36. Nebaliadae, 14, 31. Nicothoe, 15, 300. astaci, 307. Nicothoida , 299. Notodelphys, 14, 237. ascidicola, 238. Omethia , 219. Oniscus, 269. Ostracins , 138. Ostracoda, 14, 138. Ostracodes , 138. Ostrapoda, 138. Otrophesa, 296. imbricata , 299. Ozolus , 242. g aster ostei , 256. Pachycephala, 15, 295. Pandaridse, 15, 281. Pandariens , 281, 289. Pandarince, 281. Pandarus, 15, 281, 282, 286. alatus , 285. bicolor, 288. Boscii, 289. lamnce , 286. Parasita , 240. Pasithea , 101. gibba, 101. rectirostris, 101. Pectoral Lerncea , 275. Pediculus , 269. aquations, 199. salmonis , 335. Peltocephala, 15, 241. Penelladse, 15, 339. Peracantha, 14, 123, 136. truncata, 137. Ptf&Y insect e aquatique, 256. Phyllopa , 17. Phyllopoda, 14, 17, 18. Pleuroxus, 14, 123, 134. hamatus, 136. trigonellus, 134. uncinatus, 135. Pneumonura, 240. Peecilopoda, 15, 240. Polyphemidse, 14, 111. Polyphemus, 14, 111. oculus. 111. pediculus. 111, 112. stagnorum, 112. Pontia , 229. Pater sonii, 229. Pontiadce, 233. Pontiens, 233. P &> 9 4 . . TOT*- . TaMLI. CHIRQ CEPHALU S DIAPHANUS Tab. IV.. M A^a : ' v 4 A ,/V^/sAAA^^aa£»^- CHIHO CETHALU S EIAPHANUS Tab.V. CHIAOCEPHALUS DIAPHANUS. Tat. VI. D APHtTIA TULEI. II A TO lab. VIII TaT . IX . MOIUA BILAN CHI AT A, 3 . D. P S IT TACEA . . . . D ? . . . JUTS' I1 T .... D ? JUNR . D . PULEX JUTU 6 D. BOTTJNDA. TUNT ILb.X. r/\ DAMIi YE TULA 2 H. D. ITUGLONTATA . 4. D. ROTUNDA . ;i x'tbi 1. & 2 . MO IN A MCTIROSTBIS. 4*. 5. & 6. DAP UN I A PULEX . ’b & ? var. Tab . XII. CRY ^TALLIN A JUYT TakXIII. f £ i 1 pq I SIDA C EY S T ALL IN A . Tab. XI Y. Uee-re 5 ei3ia.nL feUeeve^ii Tai.XV. EURYCERCUS LAMELLATUS . 2. MACRO IHKIX LATICORNIS 3 . B 0 SMIEA L OR GIR 0 S TR1S . IAY'qXL Tab .XVII. & & <* W I P§ CO p c n a P Ph PH ? m O d O - -H P « (A H 5 P p p ft o c 4 pq •CO P P P pq ft o d> (A &H CO p H o PH p p P p-i PH PH cO ^ »o CQ P P P o P P ft PH co p % pq. W Ph p o p ft pq ft H cq 4 a l f % lab .XVIII. D? Baird clel.WWmg li£h_ Reeve BeiCham. & Reeve, imp. 1. CYPRIS TRISTRIATA. 5. C. JOANNA. 2.3. D? JUN* 6. C. MON AC HA. 4 C. CLAYATA. 7. 8. C. MINUTA. Tat. XIX. 1. CARDONA LUCEU 2. C. S1MILIS . 3. C. RHP TAN S . 4. C. H1SPIDA. 5. CYPR1S SELLA. 1 6. C. ELOUGATA. 7. C. EUSCA . 8. C. G-LBB 0 SA. 9. C. WESTWOOD11 . .11. C. VIDUA. 12. C.ELLIPTICA. 13. C. AUR.A1I TIA. 14. C. COMPRESSA. DT Baira lel.'W.WiTig.lit'K . "Reeve Benham to Reeve Ta33.ll . 1. CYTHEREIS JONESII. 2. C. ANTIQUAIA. 3. C. WHIT Eli. 4. CYTHERE MINNA . 5. C. RENIFORMLS . 6. C . ALBA. 7. C. ALBOMACULATA D r B lira, lei ."W.Wmf.lifh- Reeve BeiOxam 8> Reeve imf Tab . XXI. 1. CYTHERE INOPINATA 2. C. QUADRIDENTATA 3. C. COUVEXA 4*. C. NIGRESCENS. 12 a. /. 5. C. ACUTA. 9. C . 6. C. ANG-USTATA 10.11. 7. C PELLUCID A 12. C. 8. C AURANTIA . IMPRESSA C. VARIAB ILIS . ELAVIDA . ‘W7Wirtg\ acLiuit ~hth- Heeve BerOxam& Reeve imj Tai .XXII. CYPILIDIKA TVT AC'— ANDREI. C YPMDTNA WR2.WDA. Tal.XXIV. DT B airl Eel . WWmglith_ . CYCLOP S QUADRIC ORU IS Reeve BenRam & Reeve imj> Tab. XXV. D* Bairl del . 'W.Wing. litK. . UeeyB Eenham fcHeeve,in)£ 1 &2 CANTHO CAMP T US ITJUCATUS . 3 „ „ MINUTIGOMIS. A, 2-C 4* & 8 . MITTUTUS. Sjf. 1>*' l-.Hivt 'i.'i Vv Wnij^ hth ■1. 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