70 MOLLUSCA. PTEROPODA. 



chiferous wings, connate at their posterior base. Shell gela- 

 tino-cartilaginous, very transparent, crystalline, oblong. 



C. Peronii, Cuv. 2 inches long. Inhabits Mediterranean sea. 

 An. Mus. xv. pi. 3, fig. 10-12. 



Gen. 3. LIMACINA, Lam. 



Body soft, oblong; mouth terminal; two oval branchial fins 

 inserted at the base of the neck ; posterior part of the body 

 spiral, and inclosed in a shell ; shell thin, fragile, papyra- 

 ceous, of a spiral form, with the whorls united in a discoid 

 form. 



L. helicialis, Lam. Inhabits the Northern seas Lam. vi. 1. 291. 

 Gen. 4. CLEODORA, Peron. Clio, Lin. 



Body oblong, gelatinous, contractile, with two wings, a head at 

 the anterior part, and the posterior contained in a shell; 

 head projecting, very distinct, rounded, with two eyes, and a 

 mouth in the form of a small rostrum ; no tentacula ; wings 

 membranous, transparent, notched, at the base of the neck. 

 Shell gelatinoso-cartilaginous, transparent, in the form of are- 

 versed pyramid. 



C. pyramidata, Lam. Shell triquetrous, pyramidal, short ; mouth 

 obliquely truncated. American seas.- .Broww, Jam. pi. 43, fig. 1 . 



Gen. 5. CLIO, Lam. 



Body naked, gelatinous, oblong, turbinated, floating, with a 

 projecting head surmounted by many retractile tentacula, dis- 

 posed in two bundles ; two eyes on the upper part of the 

 head ; mouth terminal ; two oval opposite branchial fins in- 

 serted at the base of the neck ; anus and orifice for genera- 

 tion on the right side near the neck, and under the fin of 

 that side. 



C. Borealis, Lam. Body gelatinous, pellucid ; fins subtriangular ; 

 tail acute. 1| inch long. Northern seas Lam. vi. 1. 288. 

 These animals are found in calm weather at the surface of the sea, and form part 



of the food of the whale. 



Gen. 6. HYAL^SA, Lam. 



Body enveloped in a shell, with two opposite retractile fins in- 

 serted at the sides of the mouth ; head indistinct ; mouth 

 terminal, at the junction of the fin ; no eyes ; branchiae late- 

 ral ; shell horny, transparent, oval-globular, tridentated pos- 

 teriorly, open at the summit and the two posterior sides. 



H. tridentata, Lam. Shell yellowish, pellucid, thin, with very fine 

 transverse striae. Size of a nut. Inhabits Mediterranean sea. 

 An. Mus. iv. pi. 59. 



