336 PROCEEDINGS OF THE ACADEMY OF [1896. 



wliich 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, coluraellar lip reflexed ; 

 the terminations connected across the parietal wall by a strong, 

 elevated callous ledge. Axial lamina small as seen from the mouth ; 

 parietal lamina small, often double, moderately long; a small denti- 

 cle to the left of, and an elongated lamina behind and to the right 

 of its inner end. 



Alt. 18, diam. 9 ; apert., alt. 7, width Qh mm. 



Alt. 16-2, diam. 8; apert., alt. 6, width 52 mm. 



Cabo Cruz, Cuba. 



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

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

 striatelluyn it differs in the much smoother surface, thinner substance, 

 etc. The arrangement of parietal plicse is of the same type as found 

 in the two species mentioned. 



Cerion tridentatum Pilsbry & Vanatta. PI. XI, fig. 27. 



Shell moderately thick, strong, cylindrical, thelatter three whorls 

 of about equal diameter, those preceding tapering to form a long 

 cone about one-third the total length of shell. Chalky-white, 

 mottled with corneous, especially on the cone, rather polished, the 

 surface smooth except for slight growth-wrinkles, but a few whorls 

 following the two smooth, corneous nepiouic ones are seen under a 

 strong lens to be densely striated, and the base of the last whorl has 

 irregular strite. Whorls 10, with just perceptible convexity, sutures 

 well marked below. Last whorl ascending as usual. 



Aperture ovate, about four-tenths the total length, much higher 

 than wide, light brown in the throat; peristome rather thin, nar- 

 rowly reflexed, white ; columellar margin well reflexed ; parietal 

 callus thin, its edge indistinct, axial lamina small or inconspicuous 

 from front aspect. Parietal lamina small, short, central, with a still 

 smaller accessory denticle to the left of and beyond its inner termi- 

 nation, and another slightly to the right and deeper within ; all 

 visible without cutting the shell. Umbilical rimation short and 

 curved. 



Alt. 272, diam. 10; apert., alt. 11, width 8| mm. 



Alt. 25, diam. 9 ; apert., alt. 10, width 72 mm. 



Cuba (Robert Swift colln., A. N. S. P.). 



