UROCOPTIS, S. G. GONGYLOSTOMA. 231 



Length 16, diam. 3 mm.; whorls 17 (Pfr., type). 



Length 13, diam. 2.66 mm. (Pfr.). 



Western Cuba: Banos de San Diego on stones (Gundlach, 

 Arango) ; Hato Caimeto (Wright). 



Cyl. integra PFR., Malak. BL, iii, 1856, p. 47; Monogr., iv, 

 p. 704 ; vi, 379 ; Conchyl. Cab., p. 31, pi. 4, f . 16-18. GUND- 

 LACH, Malak. BL, iv, p. 47. ARANGO, Contrib., p. 120. 

 SOWERBY, C. Icon., xx, pi. 10, f. 93 (bad). 



Somewhat like U. hidalgoi, though that is a much smoother 

 shell with the neck longer. In one small specimen opened, 

 the sculpture of the pillar is reduced, there being only one 

 weak thread ' revolving above the usual lower one (fig. 74), 

 so delicate and so little twisted that it would hardly be 

 noticed except by careful examination. Perhaps this indi- 

 cates another species, but it may be only an extreme variation 

 of the usual type. 



106. U. IMPARATA (Arango). 



Shell not rimate, fusiforni-cylindric, rather solid, glossy, 

 rather closely, obsoletely striate, whitish. Spire regularly 

 tapering, entire. Suture deep, not crenulate. Whorls 17, 

 flattened, the last subangulate, shortly free. Aperture sub- 

 circular, the peristome a little reflexed. Internal column 

 encircled by two thin lamella?. Length 16, diam. 2.25 nun. 

 (Arango} . 



Cuba. 



Cyl. imparata ARANGO, Proc. A. N. S. Phila, 1882, p. 108. 

 C. imporata Gdlch., PAETEL, Catalog, ii, p. 248 (1889). 



Group of U. capillacea. 



Small, corneous or pale, unicolored, thin species, with the 

 axial armature reduced to a single lamella or spiral thread. 

 These forms were formerly grouped in Tomelasmus, but it 

 is now clear that they are very closely related to the small, 

 thin forms of Gongylostoma. The axial lamella? in this group 

 are variable structures, their proportions evidently less con- 

 stant than external sculpture and coloration in some cases. 

 There is, moreover, variation in the development of the upper 



