402 ASTRALIINJi:. 



Genus POMAULAX, Gray. 



Operculum flat, with three convex, radiating ribs, the 

 upper sub-marginal ; axis perforated. 



Shell trochiform ; whorls nodulous, fimbriated at the 

 sutures ; axis imperforate, impressed, umbilical region 

 with a curved, elevated callus ending in a sharp point at 

 the columella ; columella rounded, arched, anteriorly sub- 

 truncate. 



Ex. P. undosus. Wood, pi. 45, fig. 2. Operculum, 

 P. undosus, 2, a, 2, b. 



In this genus, which, on account of its trochus-like 

 form, has often been placed with the TrochinxB, there is a 

 peculiar circular callus round the columella ending in a 

 point, as in the genera Chlorostoma and Oxystele. 



Species of Pomaulax. 

 Japonicus, Dkr. undosus, Wood. 



Genus COOKIA, Lesson. 



Operculum ovate, smooth, flat, with a broad, spiral, 

 sub-marginal rib. 



Shell depressly turbinate ; whorls rugose, scaly, the 

 last with short, scaly spines at the periphery ; axis imper- 

 forate, the umbilical region concavely depressed and 

 surrounded by a spiral callus terminating in a point at 

 the end of the columella. 



Syn. Tubicanthus, Swains. 



