204 



Sepia. A free, cretaceous, spongy and opaque bone, inclosed in the in- 

 terior of the body, towards the back. 



S. officinalis, S. tuberculata. 



ORDER V. HETEROPODA.— Three Genera. 



Carinaria. Shell univalve, conical, flattened at the sides, unilocular, 

 very thin, hyaline; the summit spirally turned, and the back sometimes fur- 

 nished with an indented keel; aperture oblong, entire. 



C. citrea, C. fragilis, C. cymbium. 



Pterotrachea. This genus has no shell. 

 A molluscous animal, — four species. 



Phylliroe. This genus has no shell. 

 A molluscous animal, — one species. 



