GASTEROPODA. 



103 



Adeorbis. Wood. — Shell semi-globular, deeply um 

 bilicated, and furnished with few rapidly in- 

 creasing whorls ; the aperture large, oblique 

 in reference to the axis of the shell, oval or 

 semi-globular, the lips slightly separated. 

 Forbes says the operculum is testaceous and 

 multispiral. Several species ; also fossil. 



Brought from the W. Indies and China, 

 and one small species, A. subcarinata, found on 

 the British shores. 



Adeorbis 

 subcarinatus. 



Skenea. Flem. — Shell very small, spiral, flat, and 

 of few whorls, deeply umbilicated ; mouth entire, 

 circular, not quite connected with the body 

 whorl ; operculum rather spiral. Animal nearly 

 like that of Bissoa; it has large eyes. — Few 

 species ; also fossil. 



Found on the shores of Britain and other 



Sk-enea 



northern states, generally on the roots of P lanorhis - 

 Corallina officinalis. Forbes remarks that the shells may 

 be called discoid Bissoa. 



Orbis. Lea. — Shell discoidal, with flat quadrate whorls, 

 aperture square ; in other respects resembling Solarium. 

 Animal unknown. (A minute fossil, Sow.) 



Philippi mentions one small species, O. foliaceus, found 

 in the Sicilian seas, which resembles one of the Fora- 

 minifera. 



Assiminea. Leach. — Shell rather oval, light, thin, 

 covered with a horny epidermis, spire produced into an 

 acute pyramid ; whorls slightly angulated in the centre, 

 rounded beneath ; aperture elliptical, slightly modified by 

 the last whorl ; inner lip flattened ; outer thin ; operculum 

 horny, sub-spiral. Animal, having the eves at the tips of 



B 4 



