40 MOLLUSCA. 



DORIS*, Cuv. 



Have the anus open on the posterior part of the back, the branchiae 

 being arranged in a circle round it, under the form of a little tuft, the 

 whole resembling a sort of flower. The mouth is a small proboscis, 

 situated under the anterior margin of the mantle, and furnished with 

 two little conical tentacula. Two other claviform tentacula arise 

 from the anterior superior part of the mantle. The openings of the 

 genital organs are approximated under its right margin. The sto- 

 mach is membranous. A gland interlaced with the liver excretes a 

 peculiar fluid through a hole near the anus. The species are nu- 

 merous, and some of them large. They are found in every sea, 

 where their ova, resembling gelatinous bands, are diffused over 

 stones, sea- weed, &c.f The 



ONCHIDORA, Elainv. 



Only differ from Doris in the separation of the genital organs, the 

 orifice of which communicates by a furrow running along the right 

 side as in Onchidium.J In the 



I 



PLOCAMOCEROS, Leuck. 



Have all the characters of the Onchidorse, in addition to which the 

 anterior margin of their mantle is ornamented with numerous branched 

 tentacula||. 



POLYCERA, CtlV. 



Have the branchiae, as in Doris, on the hind part of the body, but 

 more simple, and followed by two membranous laminae, which cover 

 them in moments of danger ; anterior to the claviform tentacula, 



* A name first applied by Linnteus to an animal of this genus, which, however, he 

 characterized badly. It was afterwards extended by Muller and Gmelin to almost 

 the whole of the Nudibranchiata, and restored by me to its original signification. 



t Species with an oval mantle projecting beyond the foot : Doris verrucosa, L., 

 Cuv., Ann. du Mus., IV, Ixxiii, 4, 5 : Doris aryo, L., Bohatsch, Anim. Mar. V, 

 4, 5 ; Doris obvelata, Mull., Zool. Dan., XLVIII, 1, 2; Doris fusca , Id., Ib., 

 LXVII, 6, 9 ; Doris stellata, Boram<*, Act. Fless., I, Hi, 4 ; Doris pilosa, Miill., loc. 

 cit. LXXXV, 58 ;D. la>vis, Id., Ib., XLVII, 35 ; D. muricata, Id., LXXXV, 

 2 4; D. tuberculata, Cuv., Ann. du Mus., IV, Ixxiv, 5 ; D. limbata, Ib., Id., 3 ; 

 D. solea, Id., Ib., 1, 2 ; D. scabra, Id., Ib., p. 446 ; D. maculosa, Id., Ib., D. 

 tomentosa, Id., Ib. ; D. nodosa, Montag., Lin. Trans., IX, vii, 2 ; D. marginata, 

 Lin., Trans., VII, vii, p. 84 ; D. nigricans, Otto., Nov. Act. Nat. Cur., XIII, part 

 II, pi. xxvi. f. 1 ; D. gramdiflora, Id., Ib., XXVII, f. 3 ; D. figrina, Sav. Egyp., 

 Gasterop., pi. i. p. 3 ; D. concentrisca, Ib., f. 5 ; D. marmorata, Ib., f. 6, &c. 



Prismatic species, where the mantle is almost as narrow as the foot : Doris laccra, 

 Cuv., Ann. du Mus., IV, Ixxiii, f. 1 and 2; D, atromarginata, Id., Ib., Ixxiv, 6; 

 />. pustitlosa, Id., Ib., p. 473 ; D. gracilis, Rapp., Nov. Act. Nat. Cur. XIII, part 

 II, pi. xxvii, f. 10. See also Van Hassel. Bullet. Univ., 1824, Octob,, Zool., p. 

 235. 



J Onchidora Leachii, Blainv., Malac., pi. xlvi, f. 8. 



j| Plocamoceros ocdlatus> Leuck., App. Ruppel., Invert, pi. 5, f. 3. 



