ERATO. 189 



tentacles. Mantle with expanded side-lobes covering 

 the shell; siphon elongate, simple at the base. Foot 

 large, truncate in front, produced behind. 



Operculum none. 



Shell porcellanous, polished, with distinct plaits on the 

 columella ; outer lip with the margin thickened, or with a 

 marginal callus. 



The organization of the animals of this family is more 

 in accordance with that of the Volutes than with that of 

 the Cowries, although the form of the shells would seem 

 to justify their having been sometimes associated with the 

 latter. The mantle-margin is developed as in the Cy- 

 pneidce, and produces the porcellanous appearance of the 

 shells, but there are distinct plaits on the columellar lip. 



Genus erato, Risso. 



Shell obovate, polished, or rarely, covered with tuber- 

 cles ; spire short, conical, distinct ; aperture, narrow, 

 linear ; outer lip thickened towards the middle, denticu- 

 late within; columella with distinct plaits at the fore part. 



Ea;. E. laevis, Donovan, pi. 20, fig. 1. Shell, E. lavis, 

 fig. 1, a. 



The pretty little shells comprising this genus have been 

 indifferently referred both to Marginellana and to Cyprcca ; 

 from the former, however, they differ in not having the 

 marginal varix, and from the latter in the plaits on the 

 columella, and in the outer lip. 



