IIKLIX. 51 



Section II. AEGISTA, Albers. 1850. 



Shell depressed, widely umbilicated, thin, uniform corneous, 

 roughly sculptured, periphery rounded, or obtusely augulated, 

 peristome slightly expanded, a little thickened within. 

 Eastern Asiatic. H. OCULUS, Pfr. 



Section III, TRACHIA, Albers. 1860. 



Shell small, depressed, moderately or rather widely umbilicated, 

 thin with granular sculpture, last whorl deflected and constricted 

 in front, periphery rounded, peristome a little expanded, thickened 

 within, its margins approaching and connected by a thin parietal 

 callus. Indo-Pacific. H. ASPERELLA, Pfr. 



Subsection ANGASELLA, Adams. 1863. 



Shell small, depressed, widely umbilicated, with strong, rib-like 

 sculpture, periphery rounded, mai'gins of peristome approaching. 

 H. CYRTOPLEURA, Pfr. Australian. 



Ancey has changed the name to Pleuroxia, on the ground that 

 Angasella is preoccupied in marine shells, but Crosse's Angasiella 

 in Nudibranchiata bears date 1864. 



Section I. PLECTOTROPIS, Albers. 1860. 



H. HORIOMPHALA, Pfr. PI. 11, figs. 31-33. 



Widely umbilicated, thin, slightly but closely decussated by 

 oblique stride and concentric lines, suture linear; light corneous, 

 diaphanous, scarcely shining; whorls 6>>, the last not descending in 

 front, acutely carinated, base more convex, the umbilicus bounded 

 by an. angle; peristome simple, acute. Diam. 25 mill. 



Japan. 



H. CATHCART.E, Reeve. PI. 11, fig. 44. 



Widely, excavately umbilicated, arcuately rugosely striated, 

 reddish corneous; whorls 6, flattened above, thinly margined at the 

 suture, periphery compressly carinated, convex below; periphery 

 acute. Diam. 27 mill. 



Typinsan Isl. China Sea. 



