Bulla, teita oblonga fuba^quali obtufa Isevi, apertura ad api- Denticulata. 

 cem denticula acutiflima. Lw.Tnu2S.v.tA.f.3A.5.(Adains) 



Mr. Adams's obfervations are, "Shell pellucid white, 

 nd at the WaHi not common;" 



10. 

 Bulla Hydatis. Lin. Syji. p. 1 1S3. —Gmel. Syji. p. 3424. 9. Hydatis, 



C/ie)n. CoJich. ix. t. 118. f. 1019. 



Vult. Cat. Dorfet. p. 40.—Gua!t. t. 13. D. D. 



T7/ri. Lin. iv. p. 350. 

 Bulla Navicula.Dj Cojia. p. 23. t. 1. f. 10. - 



B. with an oval, fub-pellucid, thin, fragile fliell, of a 

 greenifn or yellowifh horn-colour, fometimes covered 

 with a thin, ferruginous epidermis : the body is tumid, 

 no external volution, but in its place an umbilicus : aper- 

 ture large at the bafe, contrafting more at the top, and 

 extending rather beyond it ; outer lip very thin ; inner, 

 or pillar lip a little thickened, and whitifli. Young (hells 

 are fometimes very gloffy and pellucid ; older ones gene- 

 rally fomewhat opaque, a little wrinkled longitudinally, 

 and very finely flriated iranfverfely, only obfervable by 

 the aid of a glafs ; the Columella is not vifible to the end. 

 Length one inch ; breadth three-quarters of an inch. 



Da Costa mentions this fpecies as being found at Wey. 

 mouth, but rare, and has quoted the B. Ampulla of Pen- 

 nant for his (hell; probably for no other reafon than 

 that the Ampulla was not known to him as EngliJIt. 



Ff It 



