MOLLUSCA. 795 



lamellate or cellular organ situated in the respiratory cavity near 

 the gills, and of which the interspaces are filled by a slimy fluid. 

 This organ, however, occurs in the male, although less developed 1 . 



Phalanx I. Capulo'idea. Shell conical or orbicular, scarcely 

 turbinate. Aperture very large, without any sinus or canal. 

 Operculum in some none, in others subinternal. 



Sigaretus ADANS., Cryptostoma BLAINV. Shell orbicular or 

 oblong, auriform, concealed under the foot reflected towards the 

 back. Aperture ample, entire, with labium effuse, dilate, patent. 

 Cavity of branchiae furnished with a semicanal, in connexion with 

 an incisure of mantle, and containing two pectinate branchiae. 

 Head with two tentacles depressed, conical, furnished with a tuber- 

 cle at the base. (Eyes none ?) 



Sp. Sigaretus halioto'ideus LAM., Helix haliotoidea L., RUMPH. Amb. Rari- 

 teitk. Tab. 40, fig. K, ADANSON Coquill. PI. 2, fig. 2, &c. This genus is 

 allied to Natica in the following division. 



Coriocella BLAINV. (Sigaretus Cuv., Lamellaria MONTAGU, 

 LOVEN. Shell with aperture ample, auriform, thin, horny, con- 

 cealed under mantle. Two eyes at the base of tentacles. Tongue 

 armed with barbs, very long, spirally convolute. 



Comp. Cuv. Mem. s. I. Mollusq. No. 18, pp. 26, PL I. figs, i 8. 



Sp. Sigaretus Tonganus QUOT and GAIM., Astrolabe, Zool. n. p. 217, Cuv. 

 R. Ani., ed. ill., Moll. PI. 49, fig. 2, &c. 



Siphonaria Sow. 



Is this its place ? Comp. BLAINV. Diet, des Sc. not. Tom. 32, p. 267, 

 Malacol. p. 475, EEEVE Conchol. syst. n. pp. 19, 20, MICHELIN in GUERIN 

 Magas. de Zool. 1831, 1832. 



Calyptrcea LAM. (and Crepidula ejusd.). Shell with aperture 

 ample, orbicular or oblong, convex on the back. Branchial series 

 single, of filaments often very long. Tentacles triangular ; eyes at 

 the base of tentacles towards the outside. 



Calyptrcea LAM. Shell conoid with base orbicular. A calcareous 



lamina, conical or spiral, in the cavity of shell, and adhering to its 



apex. 



animals proceeded from them, but imagined, according to the notions then prevalent, 

 that these originated from slime and putrefaction. De Hist. Animal, v. c. 15 inttio. 

 1 CUVIEE Mem. sur les Mollusq. 1. 1. p. 5, and fig. 3/. 



