CONCHOLOGY. 99 



hole ; the exterior surface ribbed longitudinally, slightly stri- 

 ated transversely. 



F. minuta. 



F. nimbosa. The scaly-ribbed Fissurella. 



Species of w^hich the middle part of the edges of the 

 aperture is hollowed in such a manner that, when placed on 

 a level surface, they touch only at the extremities. 



F. rosea. The rosy Fissurella. 



Species more depressed, edges bent up lengthwise, form- 

 ing a kind of canal. 



F. Graca. The Greek Fissurella. PI. 32, fig. 1. 



Conical, ovate oblong; striae cancellated and elevated; 

 sections tuberculated ; exterior yellowish brown or clouded, 

 interior white or light blue. 



4. Pileopsis. The Caphke Limpet. Four species. 



Easily distinguished by its form, which gave rise to the 

 common name. 



Shell oblique, sharp pointed ; cone bent forward, with a re- 

 curved, almost spiral summit, finely striated longitudinally 

 and slightly wrinkled transversely ; aperture a round oval ; 

 the margin at the base nearly round, more or less regularly 

 crenated and indented, interior with a lengthened, arched, 

 transverse muscular impression. 



Pileopsis ungarica. Pileopsis intorta. 



P. mitrula. P. subrufa. 



