MOLLUSCA. 301 



CARINARIA VITREA. 



Our first acquaintance with this extraordinary Heter- 

 opod (which would appear to hold a station intermediate 

 to testaceous and naked molluscs) occurred off Pitcairn's 

 Island, by the capture of two living examples near the 

 surface of the deep blue water which surrounds that 

 coast. We subsequently met with specimens in other 

 parts of the Pacific, from lat. 3 to 39 1 N., and from 

 2 to 26 S. ; and also in the Straits of Timor. 



The average length of the species is two inches. Its 

 structure is gelatinous, sufficiently firm, (being invested 

 in a stout membrane,) and semi-pellucid. The body is 

 smooth, cylindrical, arched, and tapers to a point at 



the tail. It has, in its interior, an opaque oval viscus 

 of an amber-colour. The head is chiefly to be distin- 

 guished by a circular mouth, and a black speck, planted 

 on each of its sides, and which would appear to perform 

 the office of an eye. The mouth has projecting lips, 

 and contains a long, hard, and cylindrical tube, or 

 tongue, provided on its inner margin with short rigid 

 hooks, which are alternately projected and returned by 

 a rapid rotatory motion : the protrusion and retraction 

 of the hooks being attended by similar changes in the 

 tube itself. An erect cylindrical fin arises from the 

 posterior third of the back, and a broader fin occupies 

 the corresponding surface of the abdomen. The dorsal 

 fin is covered by an exceedingly delicate and beautiful 



