CONCHOLOGY. 87 



this genus are generally very small, Inhabits the British seas. 

 Five species. 



Emarginula Blainvillii. Emarginula fissura. 



E. Cuvierii. E. rubra. 



E. marginata. 



3. Genus Fissurella. PI. IX. 



Animal. With the head truncated in front; two conical ten- 

 tacula, with eyes at their exterior base ; mouth simple, terminal, 

 and destitute of jaws ; two pectinated branchice projecting from 

 the cavity; mantle large, protruding beyond the shell. 



Shell. Shield shaped, conical recurved, summit entire, depress- 

 ed, concave below, perforated at the summit in the form of a key 

 hole, without a spire, the exterior surface ribbed longitudinally. 

 Inhabits the European seas. Twenty species. 



Fissurella Cayenensis. Fissurella Javanicensis. 



F. lilacina. F. fascicularis. 

 F. rosea. F. pustula. 



F. Barbadensis. F. hiantula. 



F. radiata. F. viridula. 



F. nodosa. F. depressa. 



F. nimbosa. F. Peruviana. 



F. crassa. F. gibberula. 



F. Graeca. F. minuta. 



F. picta. F. plicata. 



4. Genus Pileopsis. PI. X. 

 Animal. With two conical tentacula, and the eyes at their 

 base ; branchise formed in a row under the anterior margin of the 

 cavity, near the neck. 



Shell. Obliquely conical, anteriorly recurved, apex bent, 

 almost spiral ; aperture rounded, elliptical, the anterior margin 

 shortest, acute, slightly sinuated ; the posterior largest and rounded. 

 One elongated and arched muscular impression, situated under the 

 posterior margin. Inhabits the seas of Europe. Five species. 

 Pileopsis intorta. Pileopsis ungarica. 



P. subrufa. P. mitula. 



P. depressa. 



