Amphipods.] 



MUSEUM OF ANIMATED NATURE. 



open sea; none are of large size; their habits are 

 unknown. Ot another croup, called Squillians, the 

 genus Squilla may be taken as the type. 



The crustaceans of this genus, as at present re- 

 stricted, have the raptorial claw of a CalcuJar shape, 

 and armed on its inner edge with sharp teeth, which 

 are received when it is shut down or lolded into a 

 corre>pondin£r groove of the preceding joint, which 

 is equally compressed, and generally armed with 

 spines on its prehensile border. The carapace is 

 small, and the three last pairs of thoracic limbs 

 carry a slender elongated stylet, which represents 

 the palp. 



Fig. 3240 represents the Squilla Mantis, which is 

 common in the Mediterranean, and is occasionally 

 seen in the British Channel. It is about seven 

 inches in length, and of a pale yellowish grey ; its 

 falcular claws are armed with three teeth ; the ab- 

 dominal segments, the last excepted, have six lon- 

 gitudinal ridges. The last has a strong medial ridge, 

 and terminates in four strong teeth, and a double 

 series of fine serrations. 



The Squillae are active predatory animals, well 

 furnished with instruments of rapine, and are 

 amongst the most carnivorous of their race. They 

 generally keep at a distance from shore, swimming 

 with extreme swiftness, striking the water with their 

 caudle paddle, while their abdominal feet are in- 

 cessantly in motion. These crustaceans are most 

 abundant in the warmer parts of the ocean, and 

 inhabit considerable depths. To the genus Squilla, 

 the genera Gonodactylus and Coronis are closely 

 related. 



ORDER AMPIIIPODA. 



In this order the eyes are sessile and immoveable ; 

 the mandibles, as in the preceding order, are fur- 

 nished with a palp, the abdominal appendages are 

 always apparent and elongated, and in their joints, 

 bifutcalions, &c., resemble false feet, or pieds- 

 nageoires: they are ciliated, the ciliae appearing to 

 fuitil the office of branchiae. Many have vesicular 

 pouches placed either between the limbs or at their 

 external base. In the Stomapods and Loemodipods 

 this structure is also to be found. The tii-st pair of 

 limbs, corresponding to the second jaw-leet, are 

 always annexed to their own segment, viz., the 

 ^;rst alter the head. The anteniiie, ordinarily 

 four in number, are composed of a peduncle 

 and slender filament, sometimes accompanied by a 

 little lateral branch. The body is mostly com- 

 pressed and bent. The appendases of the tail 

 generally resemble little jointed styiets. The crus- 

 taceans of this order are all minute, and swim and 

 leap with great facility, but always on one side. 

 Some are found in streams and iivulets, but most in 

 salt water; their colour is of a uniform pale red or 

 greenish. Latreille divides these crustaceans into 

 such as have fourteen feet, all terminated by a hook 

 or simple point; secondly, such as have more than 

 fourteen feet, but of which the lour first at least are 

 not pointed and natatory'; thirdly, such as fiave only 

 ten apparent feet. 



Among our pictorial specimens of the Amphi- 

 poda, we may first turn to that well-known little 

 species, the Freshwater shrimp, or Crevette des 

 Kuisseatix, common in all our rivulets and shallow 

 water-couises. It belongs to the genus Gamniarus, 

 in which the four anterior pairs of feet are termi- 

 nated in hooks, the four next in simple points. The 

 body is divided into thirteen segments, exclusive of 

 the head, and from the seven first a lateral horny 

 plate IS continued, wliich hides the base of the 

 limbs. 



Kig. 3241 represents this species, the Gapimarus 

 Pulex of I-atreille: it is magnified at a; and at b, 

 the head and antennae are seen still more magnified. 

 This active little creature swims with great lapidity, 

 perlbrniing its movements by a series of jerks, and 

 generally at the bo'tom of the water, on its side, 

 over the soil muddy bed, into which it plunges for 

 safety. It is carnivorous, feeding on dead fishes 

 and other aquatic animals. The male exceeds the 

 lemale in size. The latter keeps her eggs until they 

 are hatched under the shelter of the lateral plates of 

 the abdomen, and the young are retained there for 

 some time alter exclusion. 



Closely related to Gammanis is the genus Atylus, 

 of which a little marine species, Atylus carinatus, 

 is an example. Fig. 3242. The body, including the 

 head, is composed of twelve joints. 



Another allied genus is that termed Melita, in 

 which the second pair of limbs in the male are ter- 

 minated by a large compressed plate, on the inner 

 surface of which the claw is folded. We give as an 

 example the Melita palmata. Fig. 3243, a small 

 crustacean found under stones on the sea-shore. 



Among the Amphipods most commonly to be seen 

 on our shores is the Sand-Hopper, Talitrus Locusta, 

 found under stones, or under the mass of exuviic 

 thrown up by the tide on sandy shores, in troops of 

 thousands, all active and leaping when disturbed in 

 Vol. II. 



! their retreats, and so prompt in gaining a fresh hiding- 

 I place or in burying themselves, that it requires some 

 address to catch them. 



We now turn 1o a singular genus, viz., Cerapus, 

 in which the antennse are very large, the peduncle 

 of the upper consisting of three, that of the lower 

 antennae of four joints. The anterior pair of limbs 

 are small, the next pair large, terminating in a 

 dilated triangular joint, dentilated and armed with 

 a sharp moveable two jointed hook. 



The Cerapus tubularis, Fig. 3244, is found in 

 abundance in the sea near Egg-Harbour, in the 

 United States. It lives in a small cylindrical tube, 

 supposed to be that of a Tubularia (zoophyte), hav- 

 ing the head and claws exposed. It is always found 

 in the midst of Sertulariae, on which no doubt it 

 feeds. It is very minute, and is represented both 

 magnified and of the natural size. 



Latreille places among the Amphipoda the genus 

 lone, regarded as one of the Isopoda by Desmarest, 

 and of which the only known species, lone thoracica, 

 is parasitic, like Bopyrus, and hides itself under the 

 carajjace of the Callianassa subtenanea, forming a 

 tumour on one side. The female is always found 

 accompanied by the male, which is of much inferior 

 size. It appears to be a rare species. Montagu, 

 who detected this crustacean in its retreat, drew it 

 out, and kept it alive for some days ; he describes 

 it under the title of Oniscusthoracicus. in the 'Trans. 

 Linn. Soc' IX. iij. 3, 4. It is represented at Fig. 

 3245 : a, the female ; b, the male. The accompa- 

 nying lines show its natural length. 



ORDER L^MODIPODA. 



The Laemodipods form Latreille's fourth order of 

 Crustaceans. As in the preceding the eyes aie 

 sessile, but the extremity of the body does not pre- 

 sent any distinct branchiae, and there is scarcely any 

 caudal termination, the two last limbs being inserted 

 at that end where the segment serving for their 

 attachment is only followed by one or two minute 

 joints. The anterior limbs, moreover, which re- 

 spond to the second jaw-feef, make a part of the 

 head. Such are their distinctive characters. La- 

 treille adds, that they have four setaceous antennae, 

 based on a three-jointed peduncle; the mandibles 

 are without palps ; a vesicular body is at the base 

 of at least four pairs of limbs, commencing at the 

 second or third pair; the body is almost linear or 

 filiform, and with the head con.sists of eight or nine 

 segments, with some small appendages in the form 

 of tubercles, at its posterior and inferior extremity. 

 The limbs are terminated by a strong hook. The 

 four anterior feetj of which the second are the 

 largest, are always terminated by a monodactylous 

 claw. In many the following four are shortened, 

 less articulated, without a terminal hook; or in a 

 rudimentary and almost useless condition. The 

 females carry their eggs under the second and third 

 segments of the body, in a pouch formed by approx- 

 imated scales (Latreille). According to M. Savigni 

 these crustaceans approximate to the Pychnogonids, 

 and with them form a link between the more typical 

 groups and the Arachnids, or spiders. 



To give an idea of the forms of these Laemodipods, 

 we select two specimens. Of these, one is the Whale- 

 louse, or Pou de la baleine, Cyamus Ceti, Fig. 3246. 

 The figure is magnified so as to show the parts to 

 greater advantage. 



The other specimen is the Leptomera pedata, Fig. 

 3247. It is also magnified. This slender claw- 

 limbed creature, with others allied to it, inhabits the 

 seas of northern and temperate Europe. They re- 

 side among the fronds of sea-weed, and crawl like 

 caterpillars, twisting their bodies about with great 

 rapidity, and vibrating their long antennae. In 

 swimming they resemble shrimps. 



ORDER ISOPODA. , 



Latreillk, who established this order, observes ' 

 that the Isopo<ls approach the Lcemodipods, as re- 

 spects the absence of palpi or mandibles, but are 

 removed from them in other details. The two 

 anterior limbs are not affixed to the head, but, like 

 those which Ibllow, are attached to their own seg- 

 ment. They are always fourteen in number, ungui- 

 culated. and without any vesicular appendage at the 

 base. The under surface is furnished with append- 

 ages which are very apparent, in the form of leaf- 

 lets or vesicular sacculi ; of these the two first, or 

 most exterior, usually cover, either totally or in part, 

 the rest. The body is mostly depressed, or broader 

 than it is thick. The mouth is composed of the 

 same paits as in the preceding crustaceans, but the 

 portions which correspond to the two upper jaw-feet 

 of the Decapods, have still more the appearance of 

 a lower lip, terminated by two palpi. Two of the 

 antennse, viz., the internal, are almost obliterated in 

 the lower forms of this order, which are all terres- 

 trial, and have the respiratory organs accordingly 

 modified. The females carry their eggs under the 



thorax, either between the scales or in a pouch or 

 membranous sac, which opens to afford a passage to 

 the young. The latter are hatched with the form and 

 parts characteristic of the species, and only change 

 the skin according to their growth. The greatest 

 number live in water ; and those which are terrestrial 

 have still the need, like other crustaceans which live 

 remote from the liquid element, of a certain atmos- 

 pheric humidity, in order that respiration may be 

 carried on, and that the branchisE may be preserved 

 in a state propitious to this function. (Latreille.) 



Of this order our pictorial specimens present us 

 with many interesting forms, but into the minutiae 

 of which our limited space prevents us from enter- 

 ing. The first which we shall notice is a curious 

 parasitic creature, which fixes its abode in the 

 branchial chambers of the prawn, indicating its 

 presence by a swelling on the side of the carapace 

 of that crustacean, but which does not appear to be 

 much incommoded by its intruding guest. This 

 little parasite appears to derive its nutriment from 

 the water circulating in the branchial cavity, and 

 which, as we know, is replete with microscopic ani- 

 malcules, and particles of animal matter. This 

 species, the Bopyrus Ciangorum, is represented at 

 Fig. 3248 : n, the upper side ; b, the animal seen in 

 profile ; c, the under side ; d, one of the feet much 

 magnified; e, a small individual considered as the 

 male, upper side ; /, the same, lower side ; g, the 

 carapace of a prawn deformed on the right side by 

 the presence of a Bopyrus. 



We next turn to a genus which reminds us of those 

 strange fossils known as Trilobites, and to which 

 indeed Dr. Buckland conjectures the species are 

 most nearly related. In the Trilobites, it is true, we 

 can discover neither antenna; nor limbs, but these 

 might have been very minute and fragile ; perhaps 

 the antennifi might, as in Bopyrus, have been want- 

 ing, and the limbs even moie rudimentary: inde- 

 pendently, however, of these, the eyes (which in 

 the females of Bopyrus are absent) and the seg- 

 ments of the body approximate the Trilobites to llie 

 genus in question, namely Serolis. Desmarest, in- 

 deed, will not admit of any resemblance or affinity 

 between Serolis and the Trilobites ; but we cannot 

 avoid leaning to the opinion of Dr. Buckland, not 

 that we mean to say that the forms are identical, 

 but they have decided points of relationship. 



The Serolis Fabricii (Cymothoa paradoxa, Fabri- 

 cius). Fig. 3249, is found on the coasts of Tierra 

 del Fuego, and the straits of Magalhaens. Capt. 

 P. P. King, H.N., observed it on the coast of Pata- 

 gonia, and at Poit Famine, where the beach was 

 covered with dead specimens. He observed numbers 

 of them alive also, among sea-weed at the bottom 

 of the water, where they moved about slowly and 

 gradually, their limbs appearing to be adapted for 

 crawling and swimming in a quiet manner, veiy dif- 

 ferent from that of the shrimp. Referring to Fig. 

 3249, a shows the back ; b, the under surface ; c, a 

 magnified view of the branchiae attached to the 

 abdominal limbs. 



Among other forms, we may refer to Cymothoa, 

 of which Cymothoa (Estrum (.Fig. 3250) is an ex- 

 ample : a, the upper side ; 6, the lower side. The last 

 section is broad and paddle-shaped. 



Another allied genus is Canolira of Leach, of 

 which the Canolira Capensis (Fig. 3251) is an ex- 

 ample. 



Related to the preceding is the genus iEga of 

 Leach, represented by the M^a. emarginata, Fig. 

 3252: a, upper side; rf, under side ; 6, anterior foot ; 

 c, posteiior foot. To this succeed several other ge- 

 nera, of which one is termed Neloeira, Leach. It is 

 represented by the Nelociia Swainsonii, Fig. 3253. 



While passing cursorily over the genera of this 

 order, we pause for a moment at Limnoria, of which 

 that formidable species, the Limnoria terebrans, is 

 well known from the ravages it commits. This little 

 Isopod, though only two lines in length, is a formi- 

 dad.e pest. It pierces the timbers of ships, and the 

 pi.es and woodwoii; of piers, with wonderful rapidity 

 and as thousands work together, the extent of mis- 

 chief produced in a short time is very considerable. 

 When disturbed it rolls itself up like a woodlouse- 

 This injurious crustacean is spread through the seas- 

 of Europe. 



To another section of the Isopods belong severa. 

 genera, as Sphaeroma, Naesa, Cilicaea, &c. 



Of the genus Sphieroma, the Sphaeroma dentata 

 (Fig. 3254) is an example. 



Of the genus Nsesa, the Naesa bidentata is repre- 

 sented at Fig. 3255. 



The genus Ciliceea presents us with the C. La- 

 treillii, Fig. 3256 



Closely allied to the preceding is Cymodocea, of 

 which the Cymodocea Lamarc-kii is an example- 

 (Fig. 3257). These genera have a broad and some- 

 what oval form of body and moderately long an- 

 tennae, but in Anthura the body is slender, the an- 

 tennae short, and the caudal fin small, the lateral 

 leaflets being shorter than the central paddle. 



Fig. 2258 represents the Anthura gracilis, magni- 

 " 2 T 2 



