123 



as specifically, from any of the class to which it belongs. It is of an 

 elongated, turreted growth, and may be said to partake in almost equal 

 proportions of the characters of two genera somewhat removed from each 

 other in the system, Turritella and Cerithium. As in TurriteUa, the shell 

 is of a solid, spirally-ribbed structure, without any indication of varices, a 

 condition not to be found in Cerithium, whilst it possesses a character 

 which, excludes it from the family Turbinacea in having a short, umbilicated, 

 twisted canal, different from that of the Cerithium,, for the passage of an 

 elevated fold of the mantle. At the base the shell is not much unlike 

 some species of Baccinum, but it is remarkable for its elongated Turritella- 

 like growth. It is, moreover, to all appearance the production of a carnivo- 

 rous gasteropod, and more strictly referable to the Canaliferous tribe than 

 the Cerithia, which, according to Deshayes, are vegetable-feeders, and 

 partake in many instances of the fresh-water habits of the Melania. 



Unfortunately Mr. Cuming is not in possession of any information re- 

 specting the shell, either touching the aminal or its place of habitation, 

 and it only remains to observe that I have not as yet found a second 

 species. 



Figure. 



Fastigiella carinata. PL 10. Fig. 46. Shell showing its umbilicus, 

 short twisted canal and elongated turreted growth. 



Genus 15. CERITHIUM, Bruguiere. 



Animal ; disk small, nearly orbicular ; head truncated beneath, 

 bordered with a fringe, and furnished with two pointed tentacles 

 bearing the eyes upon a swollen portion of their outer base. 



Shell ; turreted, prominently channelled at the base, mostly rough 

 or tuberculated, composed of numerous whorls forming a regu- 

 spire, often exhibiting an occasional varix, and in fresh- 

 water species, frequently eroded or decollated at the apex ; 

 columella arched with sometimes a reflected fold, constituting 

 the edge of the recurved canal. 



The genus Cerithium is one of rather anomalous character, from the cir- 

 cumstance of some of the species being of marine habit, others of fluviatile; 



i; i 



