TRICHOTROPIS. 



numerous sharp-pointed, bristle-like processes on the 

 edges of the carinas outside the shell; very strong, and 

 by its contraction in drying frequently breaking the edge 

 of the lip. Operculum horny, much smaller than the 

 aperture, composed of elliptical laminae, its apex or 

 nucleus lateral. 



This Genus may be distinguished from those with 

 which it has either been confounded or to which it may be 

 nearly related, viz. Turbo, Buccinum and Cancellaria, 

 by the following circunistances. From Turbo it may 

 easily be known by its thin shell, its elliptical and not spiral 

 operculum and by the absence of the ciliated lateral 

 membranes which belong to the Turbines. From Buccinum 

 it is distinguished not only by the discrepancies observable 

 in the soft parts, but also by the want of a notch at the 

 base of the aperture, and by the very indistinct canal. 

 From Cancellaria it may be at once known by its being 

 destitute of the oblique folds near the base of the colu- 

 mella ; it appears however to be the type connecting the 

 true Buccina with the Cancellariae. 



Three species only of this Genus have hitherto been 

 noticed, two of which appear to be confined to the 

 Northern Ocean; we have represented the T. bicarinata 

 from Icy Cape ; the T. borealis was brought from Melville 

 Island and a single specimen of it has occurred at Oban in 

 Argyleshire; we have named the third T. unicarinata, but 

 are not acquainted with its locality. 



