LAMELLARIA. 353 



LAMELLARIA. Montagu. 



Shell thin, smooth or striated, auriform, spire depressed 

 and very small, body whorl greatly expanded and patu- 

 lous, pillar lip greatly receding, aperture very large, entire. 

 No operculum. 



Animal with the mantle entirely investing the shell, 

 emarginate in front ; head rather broad, with two subu- 

 late tentacles, separated at their bases and bearing the 

 sessile eyes at their origin externally ; proboscis retractile, 

 long. Tongue linear, armed with teeth ; axile denticle 

 with an apical serrated hook, laterals one on each side, 

 yery large, broad, hooked, and serrated. Foot oblong, 

 obtusely quadrate in front, rounded behind. 



The genus Lamellaria as originally constituted by Mon- 

 tagu included very dissimilar mollusks, those which we 

 here retain under it and those to which the appellation 

 PleurohrancJms is applied. The original definition was, 

 " body formed of two fleshy lamellaj ; the vitals protected 

 by a convoluted shell concealed beneath the skin ; foramen 

 on the right side." The two sections of his genus " with, 

 and without plumes," are equivalent to the two genera 

 just mentioned. As the Bulla Haliotoidea had been pre- 

 viously described, Montagu does not repeat the account 

 of it, but simply mentions it first among his species, 

 as belonging to his new genus. In the descriptions ap- 

 pended to the paper (which is contained in the eleventh 

 volume of the " Linnean Transactions "), Lamellaria mem- 

 hranacea^ which is a PleurohrancJms , comes first. For 

 this reason Mr. Searles Wood regards that species as Mon- 

 tagu's type, and rejects the name Lamellaria for the spe- 

 cies here so called. But Montagu does not seem to have 



VOL. III. 7. z 



