422 



Div. 3. ARTICULATA.— CRUSTACEA. 



Class 1. 



British species, having the frontal rostrum not extending beyond the peduncle of the superior antennae, and 

 nearly straight. 



[Other genera have been proposed by Risso, Leach, P. Roux, and M. Edwards, founded upon variations iu the 

 form and proportions of the lei;s.] 



Pasiphcea, Savigny, is a vei7 interesting genus, allied to the preceding in the upper antennae, terminated by 

 two filaments ; the four fore-legs terminated by a didactyle claw, but [diftering from all the other Carides] in 

 having the external base of the legs furnished with a thread-like appendage; the claw-legs are larger, nearly equal 

 in size, very slender, and filiform ; the body is very long, very compressed, and very soft. Type, P. Sivado, Risso. 

 Found in the Mediterranean, especially in the Bay of Nice, where it is very abundant.* 



The fifth and last section of the Macroura — that of the Schizopoda — appears to unite them with 

 the subsequent order. The legs are very slender, like flattened threads, and not furnished with claws, 

 but having a longer or shorter lateral appendage arising on their outside near the base, and [the legs 

 are] fitted only for swimming. The eggs are borne between them, and not under the tail. The ocular 

 peduncles are very short. As in the majority of the Macroura, the front is prolonged into a kind of 

 rostrum. The carapax is very slender. The tail terminated, as is customary, in a svvimmeret. These 

 Crustacea are minute and marine. 



In some, the eyes are very apparent ; the lateral antennae furnished with a scale ; the intermediate 

 ones terminated by two filaments, and composed of many minute joints, as in the preceding.f 

 Mysis, Latr., has the antennae and legs uncovered ; the carapax long, nearly square, or cylindrical ; the eyes 



close together ; and the legs capillary, and formed of two thread-like fila- 

 ments. Type, M. Fabricii, Leach ; Cancer sciitatus, O. Fabricius. 



[The species of Mysis are termed Opossum Shrimps, from their singular 

 economy of carrying their eggs and young in a large pouch, with membranous 

 envelopes, beneath the thorax and between the thoracic legs. Their structure 

 has been fully investigated by Thompson in his Zoological Researches. In 

 the Encyclopedie Methodique are also some figures communicated by Dr. 

 Leach to Latreille, and evidently intended for the Malacosiraca Britanmca 

 of the former author, but which were never published by him. 



Two other genera, nearly allied to Mysis, have been proposed by Thompson, 

 founded upon oceanic species, namely : — 



Ci/nt/iia, having branchiae attached to the subabdominal fins ; and Nociiluca, 

 founded upon a luminous species, but not described with sufficient precision, 

 and omitted by M. Edwards. 

 Thysanopoda (Edwards), in which there are also eight pairs of bifid natatory feet, but the branchiae are in the 

 form of many-branched, membranous appendages, at the base of the true legs. 



The genera Pfiasmatocarcinus, Tilesius (in the Nene Annalen Weiierausch Gesellsc/iaft, vol. i.), considered by 

 Thompson and Edwards as undescribed, and named by the former Ltici/er (Leuci/er, Edwards), and that of Podop- 

 sis by Thompson, are amongst the most singular of known Crustacea, having a filiform body, with very large 

 globular eyes placed at the extremity of very long and laterally extended foot-stalks; and the legs are exceedingly 

 slender and short. According to Slabber, whose figure of one of the species has been overlooked by all Crustace- 

 ologists, there are eight pairs of legs of equal size.] 



Crypt opus, Latr., has the carapax subovoid, swollen, bent under at the sides, enveloping the body, as well 

 as the antenna and legs, having only on the under side a longitudinal slit. The eyes are wide apart. The 

 legs are like flattened threads, with a lateral appendage. Type, C. Vcfrancii, Latr. Mediterranean. 



In others, the eyes are hidden. The intermediate antennae conical, exarticulated, and very short. The lateral 

 antenna; composed of a peduncle and a filament, without distinct articulations : their base is not protected by a 

 porrected scale. 

 Mulcio, Latr., has the body very soft ; thorax ovoid ; legs like flattened threads, the majority v. ith an ap- 



Fig. 8. — Mysis vuljarii, about twice the 



natural length. 



a, one of the bihd legs. 



* [Many n(liiitii)nnl Kinera have been added to the Carides by Toly- 

 dure Roux in his Mtmnirc ,„r In Crusijicalwu ilet Criatmd de la 

 Tribu det Siiliiii^ne), Marseilles, lS:il ; and by Milne Kdwards in the 

 Aiiualcs dr> Siirnrri Niitiirrllrt, anil Jlitt. Nat. des Cruitiictl. Of 

 these it will he necessary only to notice those of Slcyunia, nearly 

 allied to PenlEus, but riilTeriiig from it and all the other genera in 

 having no appendages to th( (a!se suhnbdominiil legs, and in the modi- 

 fieations of its respiratory apparatus, there being only eleven pairs of 

 branchiiE instead of eighteen. Srrgrilri and j^cites—in which the 

 posterior pair of true legs is almost rudinienlal, or entirely obsolete, 

 the outer pair of foot jaws being immensely developed, so as to consti- 

 tute an anterior pair of legs to supply their place. These genera are 

 founded upon exotic species.] 



[Here terminates, in the system of M. Edwards, the irrcat order of 

 Decapod Crustacea, which, in his Ilhl. yal. dri Crustactt, is »ut- 

 ceeiled by an appendix consisting of " Decapodes douteux," cnmpris- 

 in|{ the genera Zoca, Cerataspis, Mulcio, and Posydon. With respect 

 •n Zoea, I have clearly proved in my Memoir, published iu the P/iilo- 



anpkical Trntisaitions, that it is a Decapod ; and therefore the observa- 

 tions of Latreille, at the end of the Decapods, cannot be adopteu.] 



t [The Schizopoda having, since tile publication of tiie secoud edi- 

 tion of this wurii, been well investigated by Kdwards and 'I'houipson, 

 have been found to be more nearly allied to (he order Stomapoda, 

 although presenting so near a resemblance to the ('arides. Tliis intiu- 

 vation was adopted by Latreille himself in his t'unrs d' Eutumuln^ir, 

 in whicli this author has proposed to give those I'uduptlialiuoui 

 Crustacea which are destitute of thoracic internal bruncliiie, bur 

 otherwise resembling the Carides, the sectional name oi Cariuioides, 

 indicative of their analogy with the last-nanietl group. The typical 

 genus Mysis is especially interesting, on account of the complete 

 transformation of all the three pairs ot foot-jaws into legs, so that, to. 

 gether with the five pairs of true legs, there are eight pairs ot loco- 

 motive organs; and as each of these is divided from the base by the 

 addition of a lateral appendage, these animals may be said tu have itot 

 fewer than thirty-two legs.] 



