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Show 94 CRUSTACEA. ConoPHIUM, Lat. C. longicornis; Cancer grossipes, L.; Gammarus longicornia Fab.; Oniscus volutator, Pall., Spic. Zool., Fascic. IX, iv, 9: Desmar., Consid., XLVI, 1, called Pernys, on the coast of Ro: chelle, lives in holes, which it forms in the mud, that is covered with hurdles, called bouclwts, by the inhabitants. The animal does not. make its ap?earance till t.he beginning of May. It wages everlastmg war agamst the Neretdes, Amphinomre, Arenicolre, and other marine Annelides, which inhabit the same locality. A curious spectacle is presented by these Crustacea, when the tide is. co~ing in; ~yriads of the~ may then be seen moving in every directton, beatmg the mud with their great arms, and dilutin 1• t .m ord er to dI' scover the.i r prey-is it one of the above meng. tioned Annelides they have discovered, which is ten or twent times larger than themselves? they unite to attack, and devou~ it. The carnage never ceases until the mud has been thorough· ly turned up and its inequalities levelled. They do not even spare Mollusca::, Fishes, or dead bodies on the shore. They mount upon the hurdles which contain Muscles, and fishermen assert that they will cut the threads that keep them there, in order to pr~cipi_tate them into the mud, where they may devour them at their leisure. They appear to breed during the whole summer, as females carrying their ova are to be met with at various pe:iods. .Waders and different Fishes prey upon them. For these mterestmg observations we are indebted to M. D'Orbigny, Senior, conservator of the Rochelle Museum and cor· responding member of that of Paris( I). The second section-HETEROPA, Lat.-is com posed of those with f?urteen feet, the last four of which, at least, are unarmed and destined for natation only. It comprises two subgenera(2). PTERYGOOERA, Latr. . The thorax divided into several segments; four antenna:: furnished With sete or hairs in bunches; all the feet natatory and the last large (1) See Eocyclop. Method., article PodocerB. (2) This and the following section, in the first edition of the Regne Animal, form th7 sec~nd of the Isopoda, that of the PltytibranclLiata. But independently of our havmg dtscovered mandibular palpi in some of these Crustacea, the form of the su~caudal appendages appears to us to approximate them much nearer to the A~phtpoda, than to the Isopoda. We may also observe that these animals, of whtch we have seen but very few, have not yet been well studied. AMPHIPODA. 95 and pinnated( 1 ); cylindrical, articulated appendages to the posterior extremity of the body. APsEUDEs, Leach.-Eupheus, Risso. The thorax also divided into several segments, but the two ante~ rior feet terminated by a didactyle forceps; the two following ones cJaviform, ending in a point aud dentated on the edges; the next six slender and unguiculated at the extremity; the last four natatory. The antenna:: are simple. The body is narrow, elongated, and has two long setaceous appendages at its posterior extremity(2). The third and last section-DEcEMPEDES, Lat.-is composed of Amphipoda, which present but six distinct feet. TYPHis, Risso. But two very small antenna::, the head large and eyes not promi· nent; each pair of feet annexed to its peculiar segment, and the four anterior terminated by a didactyle forceps. On each side of the thorax are two movable plates, forming a sort of lids or valves, which when joined, the animal folding up its feet and tail beneath, enclose the body inferiorly and give it a spheroidal appearance. The posterior extremity of the tail has no appendage(3). ANoEus, Risso.-Gnathia, Leach. The thorax divided into as many segments as there are pairs of feet, but all the latter simple and monodactyle; four setaceous an~ tenn:£; a stout square l}ead with two large projections in the form of mandibles; extremity of the tail furnished with foliaceous fin·like appendages( 4 ). (1) According to the figure of Slabber-Oniscus arenarius, Encyclop. Method., Atl. d'Hist. Nat, CCCXXX, 3, 4,-the number of feet is but eight; reasoning from analogy, I presume it to be fourteen; besides, if the figure be exact, this genus would belong to the next section . (2) Eupheua ligioidea, Risso, Crust., III, 37; Desmar., Consid., 285;-Apseuclu talpa, Leac?;-Cancer gammarua talpa, Montag., Trans. Lin. Soc., IX, iv, 61 Des· mar.: Cons1d.; XLVI, 9. See the Gammarus heteroclitua, Viviani, Phosphor. '&IarJs, II, ii, 12. N.D. The genus Rnaa, M. Edwards, Ann. des Sc. Nat. XIII, xiii, A, 292, dif. fers from the preceding in the superior antenna:, which are stouter longer and bifid. ' ' (3) Typhis ovoides, Risso, Crust., H, 9; Desmar., Consid., p. 281, XLVI, 5. (4) .B.nceusforjicularia, Risso, Crust., IT, 10; Desmar., Consid., XLVI, 6;~n· etU& ma:xillaris,· Cancer maxillaria, Montag., Trans. Lin. Soc., VII, vi, 2; Desmar. lb., XLVI, 7. |
