TROCHUS. 13 



Subgenus ENIDA A. Adams, 1860. 



Shell depressed-conical, widely umbilicate, whorls convex, con- 

 centrically granose-lirate, sutures canaliculate, last whorl carinated 

 or angulated ; aperture subquadrate ; outer lip simple, or lirate 

 within ; inner lip reflexed ; umbilicus large, margin crenulated. 

 Type, E. japonica A. Ad. Japan. 



Genus MINOLTA A. Adams, 1860. 



Shell widely umbilicated, delicate, thin, smooth ; whorls rounded; 

 spire depressed; aperture circular, the outer lip and columella thin, 

 simple, acute ; umbilicus without an internal funicle or rib. Type, 

 M. punctata Ad. Oceanica. 



Genus CIRCULUS Jeffreys, 1865. 



Shell minute, widely umbilicated, thin, with spiral striae ; whorls 

 rounded ; spire depressed ; aperture rounded-quadrate, the columella 

 and outer lips thin, simple, acute. Type, C. striatus Phil. 



European Seas. 



Genus TROCHISCUS Sowerby, 1838. 



Shell large, orbicular, umbilicated, solid, depressed, smooth ; spire 

 low-conical, formed of rapidly widening flattened whorls ; aperture 

 subquadrangular, outer lip acute, sinuous, columella simple, some- 

 what sinuous. Type, T. norrisii Sowb. California. 



Genus LIVONA Gray, 1842. 



Shell large, turbinate, thick, solid, umbilicate, whorls rounded ; 

 aperture rounded-quadrangular, smooth and silvery within ; outer 

 lip acute ; columella arcuate, simple, spreading half around and 

 partly over the umbilicus in a white callus which is deeply notched 

 in the middle. Type, L. pica L. 



Genus PHOTINULA H. & A. Adams, 1854 



Shell imperforate, orbicular, depressed, rather thin, whorls round- 

 ed, smooth or spirally striated ; aperture wider than long, outer lip 

 acute, columella spreading in a callus pad at its insertion, simple at 

 base. Type, P. coerulescens King. Southern Seas. 



Genus MARGARITA (Leach) Auct. 



Shell umbilicate, obicular, conoidal or depressed, thin ; not va- 

 riegated ; whorls rounded, smooth or spirally lirate: aperture sub- 



