OCR Text |
Show 26 CRUSTACEA. of the too great similarity between the latter and the word Portunu1 al1·eady adopted. Here the shell is at least as long as it is broad and almost cordate. All the tarsi of the feet, the claws excepted, terminate in a small, semi-elliptical, elongated and pointed lamina; the index is strongly compressed. This division also comprises but a single species, the Cancer latipes, Plancus,-De Conchis minus notis III, 7, B, C,-and which has also been figured by Leach-Malac. Brit., IV. There are three teeth front, and on each lateral edge five(1). From the swimmers we pass to those whose feet all terminate in a point, or conical and sometimes compressed ta1·sus, but never forming a fin properly so called. Those of them whose shell is tapering, forming the arc of a circle before, and na1·rowed and truncated behind, in which the claws of both sexes are alike, where the number of the caudal segments is the same as in the Portuni, and which, with the exception of the tarsi, almost completely resemble them, will constitute our second section, that of the ARoUATA. In the CANCER, Fabr. Or the Crab properly so called, the third joint of the external foot-jaws is emarginated or marked with a sinus near the internal and almost square extremity. The antennre scarcely extending be· yond the front and composed of but few articulations, are flexed and glabrous, or but slightly hairy. The hands are rounded and have no appearance of a crest on the upper edge. The radical joint of the external antennre is, in some, much larger than the following ones, and resembles a lamina; terminated by a sa· lient and advanced tooth, closing inferiorly the internal corner of the ocular cavities. The fossulre of the middle or internal antennre are nearly longitudinal. Such is the C. pagurus, L.; Crabe poupart, &c.; Herbst., IX, 59. ' Shell reddish, wide, plane, almost smooth above, with nine festoons in each lateral margin, and three teeth in front. Its claws are large, smooth, with black fingers studded internally with blunt tubercles. It is sometimes a foot wide, and weighs five pounds. Common on the Atlantic coast of France, but less abundant in the Mediterranean. Its flesh is esteemed. Dr. Leach separates it generically from the other Crabs: Malac. Brit., XVII, :x.. In the others, the lower joints of the A.ntennre are cylindrical; al· though somewhat larger, the first does not differ from the following ( 1) See the article Platyonique, Encyc. Methodique. DECAPODA. 27 ones in form or proportion, and does not extend beyond the internal canthus of the ocular fossulre; those of the intermediate antennre are prolonged in a direction rather parallel to the breadth of the shell than to its length. There are some of them-C. 11-dentatus, Fab., in which the extremity of the fingers are excavated like the bowl of a spoon: they form the Clorodius, Leach. Several species, where they terminate in a point, are remarkable for the at·cuation of the edges of the shell which terminate posteriorly by a fold and overlapping projection, in the manner of an angle. Those with a tridentated f1·ont, and whose shell only presents that projection or posterior tooth, compose his genus Carpilius. The species of this subdivision,-0. corallinus, F.; C. mauculatus, Icl., are marked with round bloodcoloured spots. They more particularly inhabit the Indian Ocean. Many fossil Crabs appeat• to me to belong to this subdivision. The Xantho, of the same, some of which, Xanth. jloridus, Leach, Malac. Brit., XI;-Cancer poressa, Oliv., Zool. Adriat., II, 3, inhabit the coast ofFrance, have their antennre inserted in the internal canthus of the ocular fossulre, and not in the outer one, as in those just mentioned. Other considerations would authorise us to augment the number of these divisions, but our limits require us merely to indicate the principal ones. The" Crabe vulgaire de nos cutes" of the first edition of this work, has in this one been placed among the Portuni.-P. m::enas. PrRIMELA, Leach. These Crustacea completely resemble Crabs, but their external antennre extend considerably beyond the front, and their stem, longet· than theit· pedicle, consists of numerous joints. The fossulre of the intermediaries, as in the C. pagurus, are rather longitudinal than t1·ansversal. But a single species is known, the P. denticulata, Leach, Malac. Brit., VIII; it is found in the British channel and in the Mediterranean. Perhaps we should refer to this species, the fossil described by Desmarest under the name of .llUUcycle rugueux, in the Hist. Nat. de Crust. Foss., IX, 9. ATELEOYoLus, Leach( 1 ). Fossulre of the intermediate antennre longitudinal; lateral antenn:£ (1) We had, at first, placed this subgenus, as we11 as the following one, among the Orbicularia. |