94 MUREX. 



The very peculiar form of the aperture in this 

 genus is a strong and never-faihng distinctive fea- 

 ture. This is oblong-oval, or perfectly oval, seldom 

 ovate, and does not gradually contract into a canal, 

 but abruptly opens into it at the same or nearly the 

 same width which it continues to retain through- 

 out the whole length of the beak. Even in the 

 division which is destitute of an exserted beak, the 

 same contour is no less observable. The straight- 

 ness of the rostrum is a much more questionable 

 mark, than the outline of the aperture, which when 

 once understood cannot easily be mistaken. 



The last section which has been added to those 

 in the Linnaean arrangement of this genus, appears 

 to be absolutely indispensable. A plaited columella 

 having been assumed as the generic character of 

 Voluta, it can only be with some strong reason 

 that shells so furnished are admitted into other 

 genera : such a reason is however found for the 

 plaited Murices in the structure of the mouth, 

 which at once identifies them, notwithstanding any 

 other claim. But they surely deserve to be set 

 apart as a distinct branch of the family : for generic 

 characters, when they lose their validity as such, 



