162 GAZA-BEMBIX. 



Until a larger number of the myriad of species shall have been ex- 

 amined, it is evident that the characters of the dentition in their 

 classification cannot be formulated except in a provisional manner. 



Genus BEMBIX Watson, 1878. 



Bembix WATSON, Journ. Linn. Soc. London, xiv, p. 603 ; Chal- 

 lenger Gasteropoda, p. 95. 



A remarkable feature of this genus is its being covered with a 

 thin extremely persistent smooth fibrous epidermis, like that of 

 some of the Helices. This epidermis swells up and becomes pustu- 

 lated in water. In form the shell recalls some of the Cantharidus 

 group, but is thinner and on the base more tumid ; the axis is per- 

 forated, and the pillar is thin, reverted and merely angulated in 

 front. The operculum is membranaceous and multispiral. ( Watson.) 



B. ^OLA Watson. PL 40, figs. 10, 11. 



Shell high, concavely conical, cariuated, sculptured on the upper 

 whorls, smooth or wrinkled below, thin, with a tumid lirated base, 

 narrowly umbilicated, with a smooth epidermis, thin, but especially 

 so on the base, more or less nacreous all over under a thin porcel- 

 lanous upper layer. Sculpture: The first three whorls (after the 

 embryonic apex) are reticulated by three sharp remote spirals, and 

 rather stronger, slightly oblique longitudinals, which rise at their in- 

 tersections into small sharp pyramidal tubercles ; the interstices are 

 a little broader than high. This system gradually dies out and 

 leaves the surface smooth, only the row of infra-sutural tubercles 

 survives in an enlarged but depressed form, and springing from 

 these some sinuous, oblique, and slightly irregular longitudinal 

 puckerings appear on the last whorl, which is nearly bisected by 

 the sharpish, slightly expressed, finely tubercled carina. This bisec- 

 tion of the last whorl arises from the great prolongation and 

 tumidity of the base, on which, below the carina, are five narrow, 

 equally parted, spiral threads, and two intra-umbilical ones, which 

 are more continuous. Besides this larger system of sculpture, the 

 whole surface is covered with minute, oblique, irregular, and inter- 

 rupted puckerings of the epidermis. Color a brownish yellow, but 

 below the epidermis there is a thin pure white porcellanous layer, 

 through which and the epidermis the sheen of the nacreous layer 

 gleams. The base is whiter, the epidermis there being very thin. 

 Inside the mouth is an exquisite roseate nacre, spire high, with a 



