360 



SHELLS AND SHELL-FISH. PART II. 



any spire ; the base widest : this in the typical species, 

 is covered by the lobes of the mantle ; in others the 

 whole animal is contained in the shell.* 



BullcB Lam. Shell internal, oval, colourless ; inner 

 lip thin ; apex umbilicated ; animal oblong, without 

 tentacula. 

 aperta. Sow. Man. f. 248. ? Guildingii Sw. {See Jig. 46.) 



Bulla. Animal furnished with two connected bony 

 plates ; shell obovate ; contracted above, and effuse 

 at the base. 



B, Lignaria. Sow. Man,, f. 251. 



Vesica Sw. Animal unknown ? probably contained 

 within the shell ; shell oval, solid ; apex umbi- 

 licated ; aperture entire ; contracted above, 

 ampulla. Sow. Man. f. 252. Naucum. Sow. Man. f. 250. 



Aplustra Schum. Animal } shell solid, but thin ; 



furnished with a distinct but depressed spire. 

 A. fascidta. Sow. Man. f. 249. 



Bullinula Beck. General shape of the last ; but the 

 spire is slightly produced and conic : a doubtful 

 type } 



B. lineata. Sow. Man. f. 253. 



Vitrella Sw. Animal ? shell internal, hyaline, 



or sub-transparent ; convolute ; the apex carinated ; 

 the substance elastic. 



V. fragilis. Sow. Man. f. 247. 



DoRiDiuM Mecken. Animal with the lobes dilated into 

 fin-like processes, but without a shell. 

 D. carnosa. Cuv. Mem. 



SuB-FAM. 4. GASTEROPTERID^. 



Gasteropteron Meek. Animal short, ovate, natatorial ; 

 the margins of the foot dilated into broad wing-like 



• The arrangement of this sub-family, founded chiefly upon the shell, 

 is purely artificial, no knowledge having been gained of the greater part of 

 the animals. Such genera as Cryptellay Sec, founded merely upon the 

 branchial covering of some unknown animal, can never be admitted into 

 Malacology. 



