OCR Text |
Show 52 CRUSTACEA. in both sexes; the shell ovoid, widely truncated, without any projection like a rostrum, and flattened. As remarked by Desmarest, we may observe on each side and above the ol'igin of the claws an oblique fissure resembling a buttonhole, longitudinally intersected by a diaphragm, ciliated, like itself, on the max·gin that communicates with the branchire, and affording an issue to the water that bathes them. 'fhree species are found in the Mediterranean( 1 ); the others inhabit Oriental seas, and one of them D. quadridens, Fabr., Herbst., X, 70, is also obtained there in a fossil state. There, the shell is sometimes nearly orbicular, or globular, and sometimes arcuatcd anteriorly and narrowed posteriorly, and dentated or spinous on the sides. The eyes are situated near the middle of the front and placed on short pedicles. DROMIA, Fab. The four posterior feet inserted in the back, and terminated by a double hook; the shell suborbicular or nearly globular, convex and woolly, or very hairy. ~ith their hind feet they seize upon Alcyonii, shells, and other bod1es, beneath which they shelter themselves, transporting them wherever they go. The most common species,-Cance1· dormia, L., Rumph., Mus., XI, 1; Herbst., XVIII, 103, is found in every sea, that of the North excepted. It is covered with a brown down, and has five teeth on each lateral margin and three in front. The fin· gers are stout, deeply dentated on the two edges, and partly rose-coloured. Some authors say that it is venomous. The Death's Head,-Cancer caput mortuum, L.; Dormia clypeat~, Act. Hafn., 1802, is smaller, more convex, almost globular, w1th three teeth on each side in its anterior margin, and has a ~hort front, emarginate in the middle and laterally sinuous. It 1s found on the coast of Barbary(2). DYNOMENE, Lat. The two posterior feet much smaller than the others, alone dorsal, and apparently unarmed; the shell widened, and nearly resembling a reversed heart truncated posteriorly, like that of the last Quadri- (1? Dorippe lanata; Cancer lanatus, L.; Desmar., Consid~r., D an:nzs I,d 1'1' b c XVII, 2;- . w• • ·; 1 er st. • XI,-67 ;-Cancer mrucarone, Herbst., XI, 68. (1236) For the other species see Desmar., Consid. Gen. sur Ia OlaBse des rr... •• t p. , et seq. ...,nov., DECAPOD A. 53 latera, and simply pubescent. The ocular pedicles are longer than those d the Dromire. But a single species, the Dynomene hispide, Desmar., Consid., XVIII, 2, is known; it is found at the Isle of France. · The last N otopoda differ from the preceding in the feet, all of' which except the claws, terminate in a fin, and from all the Brachyura in the extension of their tail. Such is the RANINA, Lam., In which the elongated shell is gradually narrowed from before backwards, and usually resembles a reversed triangle with a dentated base. The ocular pedicles are extended, and the lateral antennre long and projecting. The external foot-jaws are ~imilarly lengthened and narrow, and the extremity of the third joint is compressed into a point. All the feet are closely approximated, or almost contiguous at their origin, and from the fourth pair ascend towards the back; the two last, however, are alone on it. The forceps are compressed, have the figure of a reversed triangle, and are dentated; the fingers are suddenly ilexed. These Crustacea are closely allied to the Albunere of Fabricius, the first sub-genus of the following family, and thus form the passage from the Brachyura to the Macroura. From the approximation of the feet it is even probable that the genital orifices of the female are situated as in the Macroura. According to Rumphius, they not only leave the water, but even climb to the tops of houses; from the form of their feet, however, this appears impossible, or at least.very improbable. · A fossil species was described by Aldrovandus, which the Abbe Ranzani and M. Desmarest have since made better known( I). (1) Ranina JJ.ldrovandi, Ranz., Mem. di Stor. Nat.; Desmar., Hist. Nat. des Crust. Foss., VI, xi, 1. The fig. x, 5, 6, appears to us to belong to a Hippa rather than to a Ramina;-Ramina serrata, Lam.; Cancer raninus, L.; JJ.lbunect scabra, Fab.; Rumph., Mus., VII, T.V.;-Ranina dorsipes, Lam,; Jllbttnea dorsipes, Fab.; Rumph., Mus., X, 3; l)esmar., Consider., XIX, 2. The genus SymetMs, Fab., is unknown to us, but we presume it is 'allied to the Raminre, or to the first subgenera of the subsequent family. |