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Show 42 CRUSTACEA. selves with the fingers bent, suddenly forming an angle; very short ocular pedicles, projecting but little, if at all, from their cavities; a stony and very uneven or spiny shell, designate the PARTHENOPE, Fab. The lateral antennre of some are very short, not exceeding the length of the eyes; the first joint is entirely situated under the ocular cavities. If there are seven segments in the tail of both sexes, we have the genus Part!Lenope properly so called( 1) of Leach. If that of the males presents but five, it is his genus Lambrus(2). The lateral antennre of the others are sensibly longer than the eyes; their first joint extends to the superior internal extremity of the cavities peculiar to these latter organs, and appears to be confounded with the shell. The post-abdomen is always composed of seven segments. The claws of the females are much shorter than those of the opposite sex. The same naturalist distinguishes these Crustacea generically by the name of Eurynoma. But a single species is known which inhabits the English and French coasts(3). All the other Parthenopes, one excepted( 4) are from the Indian Ocean. In the following ones, the claws always project, and their length, at most, is double that of the body; their fingers are not suddenly bent into an angle( 5). Here the length of the longest feet-the second-barely exceeds that of the shell from the eyes to the origin of the tail. The under part of the tarsi is usually either dentated or spiny, or furnished with a ciliated fringe terminated like a club. We will commence with those whose ocular pedicles are very short, or of a mean length, susteptible of being entirely retracted (1) Partlten.lwrrida, Fab. • Humph., Mus., IX, 1; Seba, III, xix, 16, 17; Herbst., XIV, 88. (2} Pantle. longimana, Fab.; Rumph., Mus., VIII ?-P. giraffa, Fab.; Herbst., XIX, 108, 209;-P. lar, Fab.;-P. rubus, Latr.;-Cancer contrarius, Herbst., lx, 3;-P. macroclleles, Lat., Herbst., XIX, 107;-Cancer longimanus, L., fern., P. trigonomana, Lat.; Cancer prensor, Herbst., xli, 3. (3} Cancer asper, Penn., Brit. Zoo I., IV; Eurynoma asr~era, Leach Malac. Brit XVII. -r ' " ( 4) Partllenop~ a.ngulifrons, Latr., Encyc. Method.; Cancer longimanus, Olivi. ( 5) The ~rst JOmt of the lateral antenna: appearing to form part of the shell, has been m1staken by several naturalists, the second having been considered by them as the first. DECAPODA. 43 within their cavities, and whose claws, at least in the males, are considerably thicker than the other feet. MITitRAX, Leach. Robust claws; ends of the fingers like the bowl of a spoon; stem of the lateral ' antennre sensibly shorter than the pedicle; the tail composed of seven segments in both sexes. All the known species are from the American seas( 1 ). AoANTIIONYX, Latr. A tooth or spiniform projection on the inferior side of the tibre; under part of the tarsi pilose, and as if pectinated; superior surface of the shell smooth. The tale of the males presents, at most, but six: complete segments(2). J>xsA, Leach. Claws of a mean size, with pointed fingers; tibre without any spine beneath, and the tail composed of seven segments in both sexes. As in the preceding subgenera, the lateral antennre are inserted at an equal distance from the fossulre that receive the intermediate ones, and from the ocular cavities, or rather nearer to the latter. These, as in the genus Naxia, Leach, (3) have two ranges of dentations on the under part of the tarsi. Those have but a single row of dentations, or a simple fringe of thick claviform cilia, under the same joint. The latter constitute the genus Lissa of that author( 4). Among those which have a range of dentations, the feet sometimes gradually diminish in length, as happens in his Pisa(s) properly so called, and at others, the third ones, in the males, become abruptly sho1·ter than those which precede them, as in his Chorinus( 6). PERIOERA, Latr. The Pericer<£, though approaching the Pisre in the form and pro- (1) Mithrax spinicinctus, Latr.; Desmar., Consid., p. 150;-Cancer ltispidus, Herbst., XVIII, 100;-Cancer aculeatus, Herbst., XIX, 104·;-C. spinipes, ejusd., XVII, 94. The Iachus ldrcus, Fab., is perhaps a congener. (2) Maia glabra, Collect. du Mus. d'Hist. Nat.; Maia lunulata, Risso, I, 4; Li. binia lunulata, Desmar. (3) Pisa aurita, Latr., Encyc. Method.-P. monoceros, lb. (4) Pisa chiragra, Latr., Encyc. Method.; Desmar., Consid. (5) Pisa xypllias, Latr., lb. ;-ejusd., lb. P. aries,·-P. barbicornis,·-P. cornigera;- P. atyx,·-P. bicornuta,·-P. t1·ispinosa,·-P. armata, Leach, Malac. Brit., XVII; Cancer muscosus .'l, Lin.;-P. tetraodon, Lettch, lb. xx ( 6) Pisa heros, Latr., Encyc. Method. |
