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Show 72 CRUSTACEA. have but a single tooth i.n place of the index or immovable finger, and that which is movable is bent and hpoked. The superior or intermediate antennce have hut two threads. The second feet are folded up, and are more or less distinctly bifid or didactyle at their extremity; neither of the joints is annulated. The rostrum is very short. We do not separate the EGEON, Risso, or the PoNTOPHILus, Leach from Crangon. In the former, the last joint of the external foot~ jaws is twice the length of the preceding one, while in the latter they are cq ual. The second feet of the Egeones are shorter than the third and the smallest of the whole number, whilst in Crangon their length i the same. Besides, as the number of species is very limited, this generic distinction becomes the less necessary. C. vulgaris, Fab.; Rres., Insect., III, lxiii, 1, 2. (The Shrimp), about two inches long. It is smooth, of a pale glaucous green dotted with grey. That pat·t ofthe thorax which supports th~ third pair of feet, projects in a point. This species is very common on the oceanic coast of France, where it is vulgarly called the Cm·don. It is taken there annually in nets. Its flesh is delicate, and highly esteemed. In the same locality, though rarely, according to M. Brcbisson, is found the C. ponctue de rou,.e of R'I ~so; but I consider it, with him, as a mere variety. Tohe' C. loncatus-~geon loricatus, Risso; Cancer cataphraclus, Oliv., Zool., Adriat., III, 1, has three longitudinal and dentated ridges on the thorax. ~ orthern seas produce a large species, th~ Crangon boreas, Ph1pps., Voy. to the North Pole, pl. xi, 1, Herbst. XXIX, 2. PRooEssA, Leach.-Nilca, Risso. One. of th~ two anterior feet simply terminating in a point, the other m a didactyle claw; the two following are unequal slender and also didactyle. One of these second feet is very long, i~s carpu; and the pr.eceding joint being annulated, a character which on the other foot IS only found in the first of these joints. The fourth pair of fee~ are longer than the preceding and two following ones. The superior antennce have but two threads. P. edulis; Nika edulis, Riss., Crust., III 3 is of a flesh colour d otte d Wi.t ~ yellowish;. a line of small yello'w 's pots in the middle. The anterior extremity of the shell is furnished with three sharp points, the intermediate of which, or the rostrum is the long~st. The two anterior feet are equal in size, the ri~ht one formmg a forceps. This species is found during the whole year 73 in the markets at Nice. · It is also found on the coast of the department of France, called the Bouches-du-Rh'lne( 1 ). . Hn.t:ENOOERA, Latr. The two anterior feet terminated by a long hook with a· bifid extremity, and composed of very short divisious. The t~o following every large;' the hands, immovable finger, and supenor thread of u f . the intermediate antennre are dilated, membranous, and almost oh-aceous. The external foot-jaws are equally foliaceous, and cover the JllllUth. The only species known is in the collection of the Museum d'Htstoire Naturclle, and was captured in the Indian Ocean. We now pass to subgenera, in which the claws present no remark-able or insulated peculiarity. Sometimes the superior or intermediate antennre are only termi-nated by two threads. The rostrum is usually short. GNATHOPHYLLUM, Latr. The Gnathophylla are the only ones which approach the Hymenocerre in the size of their foot-jaws. The four anterior feet form didactyle claws; the second pair is longer and thicker than the first. Neither of the segments of the four is annulated(2). PoNTONIA, Latr. The four anterior feet, as in the two following subgenera, didactyle claw~, but the carpus is not annulated(3). ALPHEus, Fab. The four anterior feet also terminated by a didactyle claw, but the carpus ot' the second is articulated. The latter are shorter than the former( 4). (1) For the remaining species, see Risso, Hist. Nat. des Crust. de Nice; Leach, Malac. Hrit., XLI; and the Nouv. Diet. d'llist. Nat., E.d. II. (2) .Blpheu& elegans, Risso, <.:rust., II, 4; Desmar., Consid., P· 228. (3) .Blpheus thyrenus, Risso, Crust., II, 2; .IJ.stacu& thyrenus, Petag., V, 5; Des· mar., lb., p. 229. (4) .Blpheus malabaricus, Fab., and probably some other species, with which, however, I am not sufficiently acquainted. See Deamar., Consid., P· 222, 223. . VoL. III.---K |
