140 



K. J. Bush — Marine Gastropods referred to 



Pig. 9. 



One imperfect, live specimen (No. 52504), station 2547, off 



Martha's Vineyard, in 390 fathoms, 1885. 



Owing to the very interesting character of the 

 odontophore I have ventured to make this shell, 

 although imperfect, the type of a new genus which 

 is closely related to Choristes, for which Professor 

 Verrill constituted the family Choristidae and 

 placed it among the Tectibranchiata. Mr. Dall 

 (1889) placed it between family — ? genus Separa- 



tista Gray and Calyptrasidae, genus Mitrularia Schumacher, etc. 



Fig. 10. 



Choristella brychia sp. nov. 



Figure 10. 



This is a larger species of firmer texture than the preceding^ 

 although of the same number of whorls. Sculpture none. Color 

 dirty white tinted with brown. Where not worn, 

 the surface is slightly lustrous. Interior of aper- 

 ture very smooth and lustrous, showing a sutural 

 band of delicate rose color. Greatest width, about 

 4mm . height, about 3™'". 



One dead, imperfect specimen, station 2234, off 

 Martha's Vineyard, in 810 fathoms, 1884. 

 The Cyclostrema pompholyx Dall (Bull. Mus. Comp. Zool., xviii, 

 p. 394, pL xxviii, fig. 9, 1889), may prove to be another species of 

 this genus. 



Cyclostremella gen. nov. 



Shell minute, thin, semi-transparent, when fresh, planorbiform, of 

 few convex whorls, nearly symmetrically coiled, forming a con- 

 cavely depressed spire and large umbilical cavity. Epidermis thin, 

 nearly coloi'less. Nuclear whorl relatively large, smooth, turned 

 downward, seen only in a basal view, leaving a small pit above. 

 Suture deep and channeled. Aperture triangular-ovate, expanded 

 below, angulated above, with a relatively wide deep sinus just below 

 the suture. Peritreme thin, simple, continuous, not modified, slightly 

 attached. 



The dark animal was drawn well into the shell. The operculum 

 is very thin, almost colorless, broad-ovate, with the nucleus below 

 the center and represented by a small smooth space indefinitely 



