ODOSTOMIA. 279 



ventricose, though variable as to the degree of their 

 tumidity ; sometimes they are a little depressed iu the 

 middle, but are never planulate posteriorly. The body, 

 which, in the adult, seems always to be more or less 

 swollen, is about equal in dorsal length to the spire, occu- 

 pying from three-sevenths to four-sevenths of the total 

 length ; its basal declination is gradual and rounded. From 

 two-fifths to three-sevenths of the ventral length is filled 

 by the aperture, which is ovate, projecting, more or less 

 ample, rather broadly rounded, somewhat disposed to 

 expand below, and not very acutely contracted above. 

 The outer lip is acute, simple, and arcuated throughout ; 

 the throat is quite smooth. The posterior portion of the 

 inner lip is rounded ; the pillar lip is elongated, very thin, 

 and usually more or less curved ; even when reflected (and 

 the replication, especially above, is so narrow as scarcely 

 to be apparent) it is so little aj^pressed that the axial 

 subunibilicus is clearly manifested. The fold is so internal 

 as to be almost hidden, but when the outer lip is broken 

 away proves to be of moderate bigness. Length, two 

 lines ; breadth, one line. A variety exists, which is very 

 like duhia in shape, being narrower and less ventricose in 

 all its proportions. 



The animal has not been observed. 



Oxwich Bay near Swansea, and Bantry Bay, in Ireland, 

 are the only localities recorded by Mr. JeiFreys. Some 

 peculiarly squat and scalariform individuals (apparently 

 immature) have been taken by Mr. Barlec in Zetland. 



