CERITHIUM. 



TESTA plerumque turrita, attenuata, spira an- 

 fractibus plurimis composita, plerumque extus 

 plus minus rugosa, tuberculosa vel spinosa, 

 rar5 laevigata vel spiraliter sulcata ; apertura 

 subquadrata, vel elliptica, peritremate plerum- 

 que subincrassato, nonnunquam late reflexo ; 

 intus posticfe ultimo anfractu modificato : 

 columella arcuata, plica spirali antica marginem 

 superiorem canalis saepe reflexi efFormante. 



The Lamarckian Cerithia consist of shells of various 

 characters, belonging even to different families. Linne 

 appears to have been right (accidentally) in placing the 

 Cerithiuni Telescopium of Lamarck among his Trochi ; for 

 we think this does not belong to the Genus Cerithium;* 

 certain others also, which inhabit sestuaries and rivers, 

 appear to be distinguished from Cerithiuni in several 

 particulars, these which consist of Lamarck's Cerithia 

 muricatum, echinatum, Radula, lapidum, petricolum, &c. 

 have been named by Brongniart " Potamides'' in French 



* Since this was written an opportunity has been afforded of examining the 

 Moliuscum by which the Cerithium Telescopium is formed. The Rev. M. J. 

 Berkeley who has dissected it, seems to entertain the opinion that it may be 

 considered characteristic of the Genus Cerithium, and that it is very nearly 

 allied to Trochus. It appears also that it does not belong to the family of 

 predaceous Trachelipodes, since its stomach would indicate that its food is 

 either vegetable, or if animal, from its complicated structure and the thickness 

 of its coat in parts, something most probably of a crustaceous nature. See his 

 account of it in the XXth part of the Zoological Journal, 



