MOLLUSCA OK UNIVALVES. 



221 



that state during the voyage ; but on arriving 

 in England and being placed in sea water, im- 

 mediately recovered from their inanimate state, 

 apparently uninjured. 



The Cerithium giganteum is more than a foot 

 in length, and the only specimen which is in 

 existence is in the cabinet of Lamarck*; it was 

 fished up by an English sailor in the neighbour- 

 hood of New Holland, and is, of course, a recent 

 shell. There are fossil specimens of this species, 

 even larger than the recent giganteum, found at 

 Grignon near Paris. 



The surface of these shells is rarely smooth, 

 being generally covered with spines, prickles, 

 &c, or striped. The regularity of these pro- 

 jecting parts might furnish a sculptor with 

 models for innumerable designs in ornamental 

 architecture. They inhabit the sea ; but such 

 as have the canal straight live in salt marshes, 

 or the mouths of rivers. 



86. Plettkotoma. — Shell turreted or fusi- 

 form ; canal straight and long ; right lip having 

 a slit at the upper part, left lip smooth ; oper- 



* Now that of the Due de Rivoli. 



