ODOSTOMIA. 285 



This shell is extremely thin and semitransparent, a little 

 shining-, of an impure white hue, and a narrow suLoval 

 figure. The surface is smooth, but is curiously marked 

 with scratch-like lines of increase. There are from five to 

 six volutions, that rapidly taper to a small blunt and 

 rather depressed apex ; they are of quick longitudinal 

 increase, convex, not truly scalar, though sometimes having 

 a slight appearance of being so, and divided by a more or 

 less oblique suture, which, although not canaliculated, is very 

 distinctly pronounced owing to the basal swell of the turn 

 above it : the penult whorl is rather high. The periphery 

 of the body, whose length is about equal to that of the 

 spire, is not at all angulated ; its basal declination, though 

 rather abrupt, is well rounded. The moderately large 

 mouth, which usually occupies about three-sevenths of the 

 entire length (sometimes, indeed, even half), is subacutely 

 ovate, being broadly rounded below and slightly contracted 

 above. The outer lip is smooth within, and is more or less 

 projecting and arcuated. The upper or posterior portion 

 of the inner lip is convex ; the pillar lip, which occupies 

 nearly two-thirds of that side of the aperture, is extremely 

 thin, very narrow, scarcely in the least reflected, at first 

 subrectilinear, and then curving into the basal arch. The 

 fold is small and very obscure ; it lies very far back, but 

 considerably above the middle of the mouth. The axis is 

 imperforated. An eighth of an inch is the ordinary length 

 of individuals. 



The following localities are copied from Mr. Jeifreys"' list 

 in the "Annals of Natural History:" Guernsey; Burrow 

 Island in S. Devon ; Whitesand Bay in Cornwall ; Ex- 

 mouth ; Scarborough ; Aberdeen ; Lerwick ; lloundstone 

 and Arran Isle in Galway ; Tenby and the vicinity of 

 Swansea. 



