SCAPHANDRID^E. 243 



Synopsis of Genera. 



Genus SCAPHANDER Montfort. 



Shell involute, oblong or ovate, the spire concealed by a callus, 

 covered with a thin epidermis, spirally striated. Aperture as long 

 as the shell, narrow above, much dilated below, the columellar lip 

 concave, long ; columella revolving around a hollow axis ; parietal 

 wall smooth. 



Subgenus SABATIA Bellardi. 



Shell like Scaphander, but parietal wall bearing an entering fold 

 of callus. 



Genus SMARAGDINELLA Adams. 



Shell ovate, entirely open from the front and base ; whorls hardly 

 more than one; apex concealed; aperture nearly as large as the 

 shell, ovate ; parietal wall bearing a large spirally entering plate, 

 forming a little cup projecting into the aperture. 



Subgenus NONA H. & A. Ad. 



Shell white, the outer lip rising well above the vertex. 

 Genus ATYS Montfort. 



Shell solid, involute, oval, usually with spiral striae at both ends ; 

 aperture projecting beyond vertex and base, the lip typically folded 

 above the vertex ; columella plicate or concave, generally partly re- 

 flexed over a small umbilicus. See text for subgenera. 



Genus CYLICHNA Loveu. 



Shell rather small and subcylindrical, the spire sunken and um- 

 bilicate or closed by a callus from the inner lip ; rather solid ; aper- 

 ture as long as the shell, narrow above, somewhat dilated below ; 

 columella short, thickened, sometimes sinuous. For subdivisonssee 

 text. ' 



Genus DIAPHANA Brown. 



Shell small, thin, corneous-brown, umbilicated, swollen, the last 

 whorl shouldered or globose; spire low or sunken in an apical um- 

 bilicus. Aperture as long as the shell, rising above the vertex ; 

 peristome thin. For subdivisions see text. 



