106 M U REX. 



The very peculiar form of the aperture in this 

 genus is a strong and never -faihng distinctive 

 feature. 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 re- 

 tain throughout the whole length of the beak. 

 Even in the division which is destitute of an ex- 

 serted beak, the same contour is no less obser- 

 vable. The straightness 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 mouthy 

 which at once identifies them, notwithstanding any 

 other claim. But thev surelv deserve to be set 



