CEKION, GROUP XIV. 279 



caused me to identify Guerin's figure with the present species, rather 

 than with C. crassilabris, as some authors have done. There is more 

 or less uncertainty about most of the figures purporting to represent 

 striatellum, on account of our ignorance of the internal structure of 

 the specimens delineated. Guerin's figure is copied on pi. 46, fig. 19, 

 but my artist made the apex too obtuse. 



This species may or may not be the Pupa striatella of Humphrey's 

 Museum Calonnianum, p. 64, as that is undefined, though doubtless a 

 Gerion, 



B. BASISTRIATUM Pils. & Van. PI. 46, figs. 26, 27. 



Shell rather thin, cylindrical, the later three whorls of about equal 

 diameter, those above tapering rapidly, forming a straight-sided cone 

 about one-third the shell's length. Surface rather smooth and glossy^ 

 Two corneous nepionic whorls smooth ; succeeding one or two turns 

 densely and regularly striated ; rest of the shell smooth except for 

 slight irregular growth-wrinkles, down to the last whorl, which is 

 finely costulate. Color white with irregular longitudinal streaks and 

 blotches of brown. Whorls 9, hardly convex, the last ascending 

 slowly in front, rounded below, with a short umbilical rimation. 

 Aperture about four-tenths the shell's length, rounded-ovate, nearly 

 as wide as high, brownish within. Peristome thickened, outer lip 

 expanded but scarcely reflexed, columellar lip reflexed ; the termina- 

 tions connected across the parietal wall by a strong, elevated callous 

 ledge. Axial lamella small as seen from the mouth ; parietal lamella 

 small, often double, moderately long ; a small denticle to the left of, 

 and an elongated lamella behind and to the right of its inner end. 



Length 18, diam. 9 ; apert., alt. 7, width 6^ mill. 



Length 16^, diam. 8 ; apert., alt. 6, width 5^ mill. 



Cabo Cruz, Cuba. 



Cerion basistriatum P. & V., Proc. A. N. S., Phila., 1896, p. 335, 

 pi. 11, f. 28. 



This species differs from C. tridentatum in its round aperture with 

 strong parietal callus, and the costulate basal volution ; from C. stria- 

 tellum it differs in the much smoother surface, thinner substance, etc. 

 In the arrangement of parietal lamellae, it is like the two species 

 mentioned. It may prove to be a variety of C. striatellum, but I have 

 not seen intergrading specimens. 



