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Show 388 MOLLUSC:A.. nature of their hermaphroditism; for, like the preceding ge. nus, they have no copulating organ, but fecundate them. selves. Their heart does not embrace the rectum, but varies as to situation. But two genera of this order are known, in both of which the shell never approaches in the least to the turbinated form. PATELLA, Lin. The entire body covered with a shell, formed of a single piece, in the form of a broad-based cone; a cordon of little branchiallamellre under the margin of the mantle; the anus and genital orifices somewhat to the right and above the head, .which is furnished with a thick and short snout, and two pointed tentacula, on the external base of which are the eyes; the mouth is fleshy, and containing a spiny tongue, which inclines backwards, and is reflected deeply in the interior of the body. The stomach is membranous, and the intestine long, thin, and greatly flexed; the heart is forwards, above the neck, and a little to the left( 1 ). Some species abound on the coast of France. CHITON, Lin. A range of testaceous and symmetrical scales along the back of the mantle, but not occupying its whole breadth; edges of the mantle coriaceous, and furnished either with a naked skin or little scales, which give it the appearance of shagreen, or with spines, hairs, or setaceous fasciculi. Under these edges, on each side, is a range of lamellar, pyramidal branchice; and before, a membranous veil on the mouth supplies the want of tentacula. The anus is under the posterior extremity. The heart is situated behind, on the rectum; the stomach is membranous, and the intestine very long and gt·eatly (1) I separate from the PAT:ELLJE and an·ange among the TnocnornA, all the animals comprised in the genera, CnEPIDULA, NAVICELL.A, C.ALYl'TR.iEA of :M. de Lamarck, to which I add the CAPULI; and his genera Fxssun:ELLA, E:nunonruu, and PAnMoraon.A, or Patella ambigua, Chemn., XI, 197, 1918, I place amongthe s.cUTID~ANCHI.AT.A. The UMBRELLA, Scutm, Montf.l-Patella umbrella, Martini,JI, VI, 18, IS one of the TECTIBRANCHI.ATA. The Pat. anornala, Miill., belongs to the B:aAcmoPOD.A and is my genus OmHcuLus. The other species quoted by Gm. remain in the genus Patella. GASTEROPODA CYCLOBRANCHIAT A. 389 contorted. The ovary is situated over the other viscera, and appears to open on the sides by two oviducts. A few small species are found on the coast of France; very large ones abound in the seas of hot climates( 1 ). (1) The CBITONELLI of Lamarck, and all the species of CHITON of authors, should be left in this genus, of which M. de Blainville has thought proper to make a. separate class, called Por.YPL.AXIPHonA, supposing that it leads to the Articulated Animals. |
