8tt 



MUSEUM OF ANIMATED NATURE. 



[Stomapom. 



intt-nnae and the peduncltH of th« internal one» iio 

 lonit, anil wlio«e feet are all monodacfylous ; and, 

 finally, it cannot he referred to the crawfishes or 

 lobster* (Aslai-us), whose shell is differently formed, 

 BO'lVhicli have the external natatory blades of the 

 tail composed of two pieces; but Denmarest thinks 

 that it is to the last-named genus that Kryon most 

 upproximalCK. taking into consideration its general 

 chniacler. He regrets that he has not been able to 

 •atisiy himself whether the four anteniur are in- 

 •erted on the same horizontal line or not, a fact 

 which would have assisted him in his comparison 

 with other genera. 



Vtg. 322;) represents the Eiyon Cuvieri. It is 

 from the lithographic limestone of rappenheim and 

 Aichstedt in the Margmvial of Anspach. The ca- 

 rapace is finely granulated above, marked by two 

 deep and narrow notches along the two latero-anterior 

 boidei-s, and finely crenulaled on the posterior part 

 of the lateral bordeis. Jt measures about five 

 inches in length. 



The fossil I'orms of Decapod crustaceans, it may 

 be remarked, are very numerous, and have been 

 loiind in nn extensive series of fossililerous beds, 

 below an<l iiUhe chalk, up tostiiita of comparatively 

 recent formution. Their lemains are olten in a 

 •ingulaily perfect slate of preservation, even to the 

 eyes, antennas, and bianchiie. 

 ' We here close our sketch of the Decapod crusta- 

 ceans, and advance to the next order, which we 

 khall find to contain some curious and grotesque 

 forms, differing in many structural points of great 

 consequence from any of the Decapods, and more 

 particularly in the arrangement of tlie branchial or 

 respiratory apparatus, which is in the form of plu- 

 mose appendages to the limbs. 



ORDER STOMAPODA. 



N this order of crustaceans the general form is 

 elongated, and well adapted for aquatic provision. 

 They have always a thomcic section, but in most 

 the ophthalmic and antennular rings are not con- 

 founded with the rest of the head ; and the carapace 

 itself exhibits many variations of structure, and is 

 generally composed of segments moveable on each 

 other. "Sometimes, however, all the rings are con- 

 solidated into a single piece. The conformation of 

 the abdomen is even more variable still ; but in 

 general consists of segments, and terminates in a 

 • caud.^1 tin, composed of the seventh segment and 

 appendages of the sixth. The eyes are carried on 

 a jtair of moveable peduncles, olten of great length. 

 The internal anteniuE are rather long, and termi- 

 nate in two or three multiarliculate filaments; the 

 external antenme are very variable, and the ba>al 

 joint of their peduncle mostly carries a laige ciliated 

 blade. The month is far more simple than in the 

 Decapods ; it is composed of an upper lip, a pair of 

 mandibles, a lower lip, two pair of jaws, and a 

 single pair of jaw-feet; the latter indeed are some- 

 times wanting, but where present are transformed 

 into swimming feet; and the seven following paii-s 

 of limbs are so constructed as to form either swim- 

 ming or prehensile organs. 



With respect to the limbs, indeed, of the Stoma- 

 jHvis, they usually amount to the luimber of seven 

 or eight pairs, often presenting the same details of 

 conlormation. They are mostly provided with an 

 appendage or palp, and some have at the base a ve- 

 sicular appendage, which is oilen flat and rounded ; 

 the three last |>«irs, and sometimes more, are always 

 natatory, and the first pair, and oOen the tii'st four 

 pairs, prehensile, but never terminate in a true pin- 

 cer, being only subcheliform, a moveable claw falling 

 on the preceding joint. The greater part of these 

 limb* are approximated to the mouth, or even 

 closely applied to it, and it is to this circumstance 

 that the appellation stomapods refei-s (arofta, a 

 mouth, »»« »•*•», a fool). 



The alxlominal or false feet are generally found 

 to amount to six pairs; and it is to the.se that the ! 

 branchis, in the form of tufts or plumes, are at- 

 tached, at least where such organs can be detected, 

 for in some no tufts, fringes, or other special organs 

 of respiration can be detected, the necessary puri- 

 fication of the blood being effected, as is sup- 

 posed, over the general surface of the body. These 

 branchial firinKes, though ordinarily attached to the 

 base of the false or alxlominal feet, are nevertheless |i 

 in tome instances affixed to the base of the thoracic < 

 ftet, and consequently suspended under the thorax ; 

 btit this plan is not according to the general rule. ^ 

 Fig. 3230 will serve to convey a clear idea of the 

 api>earance of the branchial tufts or fringes in the 

 present group. A, one of the branchiic of Thy- 

 aanopoda: n.base of the posterior limb ; r, the palp; 

 A, branchial fringe : B, one of the branchiip of 

 Squilla ; a, ba<e of the false foot ; b, branchial 

 fringe ; c and d, the two terminal blanches of the 

 W»e foot : C, one of the portions of which the 

 branchial fringe of the preceding is composed : a, 

 the base; 6. the filaments into which it ramiiios: 

 D, one of the abdominal false feet of Cynthia ; a, 



the basal joint ; b, the branchial apparatus ; c, 

 lamellar appendages. 



With a modification of the branchial organs, we 

 shall not be surprised to find a modification also 

 of the apparatus of circulation. The heait, instead 

 of being situated in the centre of the thorax, extends 

 through the abdomen, in the form of a long cylin- 

 drical tube, giving off arteries, and receiving blood 

 from abdominal venous reservoirs. The stomach is 

 unarmed with teeth. M. Milne Edwards divides 

 the Stomapods into three tribes ; viz., the Caridoi'ds, 

 the Uicuirassed, and the Unicuirassed. 



The Caridoid stomapods bear in their general 

 form a close proximity to the shrimps ; the body is 

 thick and slightly compressed at the sides; the 

 head is confounded with the thorax, and all the 

 rings of the latter, with the exception sometimes of 

 (he last one or two, are united together. The 

 abdomen is considerably developed, and consists 

 ordinarily of seven rings, the first five of which 

 carry false natatory feet; the terminal fin con- 

 sists of five fan-shaped blades. Sometimes no 

 bianchiiE are present, sometimes vestiges of them 

 are found attached to the abdominal feet; and 

 sometimes, on the contniiy, they are grea'ly de- 

 veloped and suspended under the Ihoiiix. The ca- 

 rapace is very ample, and descends low on each 

 siile; it presents only a rudimentary rostrum in 

 front. 



To this group or tribe belongs the genus Mysis, 

 containing the opossum shrimps, so called from 

 having a pouch lor the reception of the eggs and 

 young, analogous to that of the Marsupial quadru- 

 peds. This pouch is formed by a flabelliform ap- 

 pendage or scale, of considerable size in the females, 

 and attached to the base of the two last paii-s of 

 thoracic feet; these appendages are bent under 

 the sternum, and, overlapping each other, constitute 

 a receptacle for the e^gs, and also of the young 

 during the early part of their life. According to 

 Mr. Thompson, the eggs, enveloped in a gelatinous 

 fluid, when received into the pouch are consider- 

 ably moie advanced than those of shrimps, crabs, 

 ice, but by no means so numerous, "a circumstance 

 more than compensated by the rapidity with which 

 one brood succeeds another during the whole of the 

 spring and summer months. The number of broods 

 produced by one individual, as well as the time oc- 

 cupied in their evolution, have not been determined ; 

 but the changes which the embryo undergoes in con- 

 figuration are sufficiently obvious. In the present in- 

 stance these cannot be considered as metamorpho- 

 ses, but simply a gradual development of parts. 

 The first change perceptible in the eggs after their 

 reception into the pouch is a slight elongation at 

 one end, and the appearance of two short membei-s 

 on each side ; this elongation, which proves to be the 

 tail, increasing in length, shortly after becomes 

 forked at the end, accompanied by a proportional 

 growth of the four lateral members, and which are 

 the rudiments of two paire of antennae in the per- 

 fect animal. The embryo going on thus with a 

 progressional development from day to day, begins 

 to assume a more complete form, and an approxi- 

 mation to that of the parent, in which stages 

 the divisions of the abdomen, the tail, the pedun- 

 culate eyes, and the various members are suffi- 

 ciently distinct. A still more close resemblance 

 to the perfect animal is attained before the young 

 are finally excluded, which is effected by the 

 parent spreading open the valves of its pouch, 

 when the whole brood emerge at once into the 

 ambient element, and in most of the species con- 

 tinue associated with the community from which 

 they sprang." 



Ihe opossum shrimps abound in the northern 

 seas; the Arctic ocean teems with myriads forming, 

 not troops, but vast clouds, spreading over leagues 

 of water, and affording sufficient and most nutritive 

 food to the whale, and to the prodigious shoals of 

 salmon which visit the shores of Boothia and Ihe 

 mouths of rivers, in July and August, and upon 

 which the inhabitants of that dreary region depend 

 in a great measure for their store of winter provisions. 

 During summer the opossum shrimps absolutely 

 crowd the mouths of the rivers, and there their 

 destroyers revel in a perpetual feast. 



Fig. 3231 represents the Mysis Fabricii, Leach, 

 magnified ; a, ttic last ring of Ihe bmly or terminal 

 fin ; ft, the base of one of the lateral antennae ; c, the 

 base of one of the inner antennte ; <i, one of Ihe se- 

 cond pair of jaw-feet ; e, one of the first pair of jaw- 

 feet. 



Another example of the genus is the Mysis vul- 

 garis. Fig. 8232, magnified. 



This species is common on the Irish coast, where 

 in some parts it is very abundant, associated myriads 

 forming a wide belt along the margin of the water. 

 Like the shrimp these crustaceans swim in a horiion- 

 tal manner, and when pursued by fish, often spring 

 out to a considerable height alwve the surface. 



To the caridoid section may be relerreil that sin- 

 gular genus termed Lucifer — remarkable for the ex- 



cessive length of the anterior portion of the head- 

 the extreme brevity of the thoracic section, where 

 the mouth is seated; and the great length of Ihe 

 abdomen and of its several segments. The eves are 

 I carried at the end of long and somewhat club-shaped 

 I peduncles. There are no thoracic or abdominal 

 branchiae. 



Fig. 32.'J3 represents the Lucifer typus, magnified 

 and of the natural size. It swarms in the troju 

 cal latitudes of the Atlantic, and is luminous, con- 

 tributing, with other minute phosphorescent' crea- 

 tures, to the nocturnal effulgence of the ocean. A 

 distinct species, Lucifer lieynaudii, exists in the In- 

 dian seas. 



The Bicuirassed Stomapods present us with 

 forms of strange aspect, remarkable for their 

 rounded shape and the transparency of their in- 

 teguments. The carapace forms a lamellar leaf- 

 like shield above, covering the dorsal aspect of the 

 thorax, and the thorax is equally flat and resem- 

 bles a thin plate placed horizontally, and it is to 

 these two bucklers that the term Uicuirassed or 

 double-cuirassed refers. The abdomen is small, 

 sometimes rudimentary ; the false leet are but little' 

 developed. The true limbs are from seven to eight 

 pairs, of which the first pair are very short, and some- 

 times also the last, whilst the others are long and 

 slender, and formed for spreading out over the sur- 

 face of the water, on which they can rest. The ex- 

 ternal antennae are long and stout; the eyes are at 

 the end of long peduncles. There are lio organs 

 which can be considered as branchiaj. To this sec- 

 tion belongs the genus Phyllosoma, of which one 

 species, the P. Mediterranea, is found in the warmer 

 seas of Europe, and another, P. Sarniense, Liikis, 

 has been taken at Guernsey ; the seas of Africa, 

 India, and New Holland furnish the rest. 



So transparent are these crustaceans, that as they 

 float on the clear surface of the water they would 

 escape observation, were it not for the beautiful 

 blue colour of their eyes, by which their presence 

 is betrayed. 



Fig. 3234 is the Phyllosoma commune, a native 

 of the seas of Africa and India ; and Fig. 3235, the 

 Phyllosoma clavicorne, found also in the same loca- 

 lities. Fig. 3236 represents the eyes and antennae 

 of two short-tailed species : n, those of Ph. laticoine, 

 from the Indian seas ; ft, of Ph. brevicorne, from the 

 seas of Africa and Asia. 



The Unicuiiassed Stomapods have the thoracic 

 integument in the form of a single buckler, elongated 

 and quadri'ateral, generally enlarged and free behind, 

 and covering the head, with the exception of Ihe 

 eyes and antennae, which are based upon a distinct 

 anterior segment. All the jaw-feet, of which the 

 second are very large, and the four anterior true 

 limbs are close to the mouth, on two converging 

 lines. The first pair of thoracic limbs are largely 

 developed, and constitute great raptorial organs; 

 the last joint bends back like a long claw along the 

 internal border of the preceding joint, so as to form 

 a sort of pincer by which the animal seizes its prey. 

 The three succeeding pairs of feet are much smaller, 

 and terminate in an oval hand armed with a move- 

 able claw, disposed so as to bend back and consti- 

 tute an organ of prehension. At the base of the 

 limbs externally is a small flattened vesicular ap- 

 pendage, supposed by some to be a respiratory 

 organ, but distinct plumose branchiae, in most, are 

 affixed to the base of the false abdominal feet. The 

 abdomen is well developed, and consists of seven 

 segments, of which the last is modified into a broad 

 caudal blade. As examples of this group, we select 

 the genera Elrichthus, Alima, and Squilla. 



In the genus Eriehthus the carapace is very large 

 and convex, armed anteriorly with a spiny rostrum, 

 and posteriorly with strong >pines ; the abdomen is 

 broad, and the caudal plate large. The eyes are 

 well developed and pear-shaped. The internal an- 

 tenna? have three filaments. The limbs are small, 

 and even the raptorial claws are but moderate. 



The Erichlhus vitreus. Fig. 8237, will serve to 

 convey a clear idea of the general form and charac- 

 ters of the genus : it is a native of the South Atlantic 

 Ocean. Fig. S238 represents another species, Erich* 

 thus Duvancellii, from the Gulf of Bengal. 



The genus Alima differs t'rom Eriehthus in the 

 length and narrowness of the carapace, and the slen- 

 derness of the abdomen, which terminates in a large 

 leaf-like paddle. The eyes are carried on slender 

 peduncles directed outwards. The posterior border 

 of the carapace is generally notched, so as to leave 

 exposed the two last thoracic segments. The tho- 

 racic feet are formed as in Eriehthus ; the abdominal 

 flilse feet arc large, but are in general destitute of 

 branchiae, though sometimes rudimentary branchiae 

 exist on the first pair. Some species have the claw 

 of the raptorial feet armed with spines, in others it 

 is unarmed. Among the latter is the .\lima hyalina, 

 a native of the seas of New Guinea, represented at 

 Fig. 3:339. The Erichthiaos, it may here be observed, 

 have as }'«t been obserred oaly in tropical latitudes, 

 and s«neraliy at a distaiK* bom shore, out in the 



