294 PYRAMIDELLID.'E. 



the basal diameter of an iudiviJiial that measured the fifth 

 of an inch in length. 



Portmarnock, in Dublin Bay, was the s^jot from whence 

 Mr. ^Varrcn procured the original type of the species. It 

 is a very rare shell, but is comparatively plentiful dead in 

 shell-sand, from Burrow Island, S. Devon ; and has also 

 been taken at Falmovith ; on the southern and western 

 coast of Ireland ; and the west coast of Scotland, 



0. TRUNCATULA, JeffVcys. 



Turreted-subcylindraceous, transparent, sculptured, though 

 very obscurely : whorls six or seven, high, convex, of slow lon- 

 gitudinal increase. Mouth not more than a third of the entire 

 length : pillar with a pliciform twist. 



Plate XCVI. fig. 8. 

 Odostomia (ru/icatula, J kffr'eys, Ann. Nat. Hist, new ser. 18,50, p. 10i>. 



This very interesting shell combines in its characteristics 

 the features of Odostomia, Chemnitzia, and Truncatella. 

 It is turreted, thpering, subcylindrical, extremely thin, 

 more or less transparent, and of an uniform and somewhat 

 glossy white. At the first glance it appears to be smooth 

 or nearly so, but on careful examination, displays both 

 slanting longitudinal wrinkles and slightly elevated spiral 

 lines. The former are regular, though obscure, and are 

 chiefly evident on the upper portion of the volutions, im- 

 parting to them a kind of subsutnral puckered appearance : 

 the latter do not pervade the entire surface, are more 

 apparent in some examples than in others, and are chiefly 

 visible upon the basal portions of the smaller turns, and 

 occasionally upon that of the final one likewise. The 



