No. 2369. NEW MOLLV8KB FROM CUBA— TORRE AND HENDERSON. 255 



Measurements are: Length, 12.5 mm.; major diameter, 11.5 mm.; 

 minor diameter, 8.75 mm.; length of aperture, 5.5 mm.; width of 

 aperture, 4.5 mm. 



This species is found at Camaguey Province, Cuba, on rocks about 

 the entrance of La Cueva del Circulo in the eastern portion of the 

 Cubitas Mountains. 



This very handsome species is easily distinguished by its hard 

 polished old-ivory surface which, to the naked eye, seems to be 

 sculptureless and smooth, by its globose shape and relatively greater 

 proportion of breadth to length, and, finally, by its reddish tip and 

 entire lack of color bands or spots. 



OPISTHOSIPHON (OPISTHOSIPHONA) BIOSCAI, new species. 



Plate 40, figs. 4 and 6. 



The shell is ovate-oblong, rather thin but strong; apex decollated, 

 leaving three and a half to four moderately convex whorls, the last 

 being very slightly solute. The umbilicus is (a) almost wholly closed 

 or (b) partially so by an expansion of the inner peristome. The color 

 is of a very light straw ranging through slightly darker yellowish 

 tints to an amber or wine color. A series of brown spots encircles 

 all the whorls, there being five such series on the last whorl of the 

 holotype, but as many as eight in some specimens. In no instance 

 are there solid color bands. The sculpture consists of axial thread- 

 like riblets somewhat arched forward below the suture and never 

 quite regularly disposed. In the typical subspecies these riblets are 

 coarser (five to the millimeter) and these are partially effaced in the 

 middle portion of the whorls, especially on the last two. In another 

 subspecies the axial threads are finer (ten to the millimeter) and are 

 not effaced. At the sutures, which are deeply impressed, most of 

 the riblets, either singly or in tufts, form hollow white bulbs projecting 

 up to touch the next whorl above, thus irregularly crenulating the 

 sutures. A series of spiral cords are present within the umbilicus. 

 These are crossed by the axial threads forming small projecting 

 lamellar processes at the intersections. The vertical aperture is 

 ovate and obtusely angled above. The peristome is double, having 

 an inner peritreme that hardly projects and an outer peritreme which 

 is but moderately expanded on the outer side but widely so on the 

 inner side, even to covering (a) almost wholly, or (6) partially the 

 umbilical opening above which it spreads over and (a) becomes 

 adnate to the adjacent portion of the contiguous whorl or (b) merely 

 touches it; it then forms above the aperture a delta-shaped expansion, 

 roughly laminated on its face. This expansion supports and partially 

 merges into a recurving siphon which bends down into the space 

 back of the solute portion of the last whorl. This siphon opens into 

 the shell by a small puncture just back of the aperture. 



Measurements are given under the subspecific heads. 



