64 FISSURELLA. PILEOPSIS. BULLA. 



Crepidula, | 



Ancylm, \ P"^'^^"' 



Parmorphorufi is found in the seas of New 

 Holland and New Zealand. The margin of the 

 next genus is distinguished by a slit : the shell 

 is conic. (Plate 2.) Fissiirella has the top of 

 the shell perforated ; it is called the key -hole 

 limpet, from the shape of the aperture. Pileopsis 

 is obliquely conic. It was with this division that 

 the curious Hipponyx ranked. 



" Calyptrcea is very thin and brittle, with an 

 internal lip. (See Frontispiece.) 



" Crepidida has the shell partly covered, or 

 arched : it looks like a little slipper. 



" Ancylus spina-rosa is a pretty species from 

 the south of France : the genus is fluviatic. A, 

 lacustris and Jluriat ills are both natives of our 

 fresh-waters. 



" The next family, Bullceana, has 



uicera Bulla. 



Biillcea Bulla. 



Bulla ,...The same. 



" Acera and the following genus have each but 

 one species, Bulla carnosa and B. aperta of 

 Linnseus. The original genus Bulla was com- 

 posed of an assemblage of shells of various cha- 



