MACROCERAMUS, CUBA. 135 



corneous-brown, sometimes defined by a slightly darker band. 

 Surface slightly or not glossy, very finely and closely sculp- 

 tured with thread-like oblique stria, which usually crenulate 

 the sutures a little. Whorls convex, the last having a very 

 low basal keel, sometimes wanting, defining the very convex 

 base. Aperture subcircular, slightly oblique, built forward 

 to the anterior outline of the shell. Peristome slightly ex- 

 panded and thickened, whitish, dark-bordered within, the 

 margins approaching; columellar margin arcuate, dilated, 

 generally concave between the columellar fold and the mar- 

 gin. Axis slender, distinctly twisted spirally within. 



Length 15, diam. 4.5, apert. 3.6 mm. ; whorls 11. 



Length 15, diam. 4, apert. 3.3 mm.; whorls 12%. 



Length 11, diam. 4, apert. 3.3 mm. ; whorls 9%. 



Santo Domingo (Gabb) ; near the Amina river (Robert 

 Swift coll.). 



? M. cyrtopleurus and M. gundlachi, specimens from ' ' pres 

 du Rio Amina, sur un gazon court (Hjalmarson)," CROSSE, 

 Journ. de Conchy!., 1891, p. 132. 



Very much more finely striated "than the smaller M. her- 

 manni, which agrees in having a convex base and very weak 

 or obsolete keel. About 30 specimens before me, collected by 

 Gabb and others, agree closely in sculpture, except that in a 

 few shells the thread-like striae are more spaced on the last 

 whorl or two. The size of the shell and the length of the ter- 

 minal cone vary somewhat widely. 



Gabb also collected a very small form apparently referable 

 to M. subcylindricus, measuring 9 to 10 mm. long, 3 wide, 

 with about 10% whorls; but unfortunately he gave no local- 

 ity but Santo Domingo. The axis is distinctly spiral, as in 

 the type form. 



EAST AND CENTRAL CUBAN SPECIES. 

 I. Base of shell rounded, not carinate. 



1. Periphery bordered below with a dark band, another 

 at or around the umbilicus; outer lip more or less 

 expanded. Group of M. pazi, sp. no. 18 to 22. 



2. Obliquely streaked on an opaque whitish ground, or 



