1/0 SPECIFIC 



Habitat unknown. 



The general appearance of the shell bespeaks it 

 a Helix, and not a Trochus as it has hitherto been 

 designated. The convexity of the cohunella, and 

 the upright situation and form of the aperture, ir- 

 resistibly confirm the first impression. 



PLATE XXIV. 



This plate is intended to point out to beginners 

 in Conchology the great difference which exists, in 

 certain species, between the shell in its young, un- 

 finished state and the same arrived at its perfec- 

 tion. The examples adduced are among the most 

 conspicuous, but there are many others of which 

 it would be very beneficial to students to acquire 

 an early knowledge. 



The mature specimen of Buccinum Vilex is 

 given in Plate XXI. fig. 3. 



