90 CYCLOSTREMA. 



C. EXCAVATA, Carpenter. PI. 31, figs. 36, 37. 



Flatly convex above, flattened below, the wide umbilicus defined 

 by an angle, minutely spirally striated, last whorl angulated at the 

 base, peristome thin. Diam. 6 mill. 



China Sea. 



C. ATOMUS, Issel. PI. 31, figs. 38, 39. 



Narrowly umbilicated, somewhat solid, greenish, a little shining, 

 obliquely longitudinally striate; whorls 4^, rapidly enlarging, 

 slightly convex, the l^st subangulated at the base, umbilical area 

 longitudinally crispate; peristome thickened, continuous. 



Diam. I'o mill. Suez. 



C. Nevilli, H. Adams. PI. 31, fig. 40. 



Narrowly umbilicated, disk-like, subpellucid, shining, thin, spirally 

 lirate and radiately striate, smooth at the periphery, spire subplane, 

 suture scarcely impressed; whorls 4, moderately increasing, flattened, 

 the periphery angulated, base more convex; peristome simple, um- 

 bilicus with callous margin. Diam. 4'5 mill. 



Ceylon. 

 C. MiLiTARis, Jousseaume. PL 31, figs. 41, 42. 



Widely umbilicated, depressed, thin, pellucid, slightly convex 

 and faintly, finely, irregularly striate above, base nearly plane, 

 equally striate, the strise becoming stronger upon the walls of the 

 umbilicus, with a spiral thread-like carina near the periphery of the 

 base, and another close to the umbilicus. Diam. 2'75 mill. 



Prmce's Isl., W. Africa. 

 C. AREOLATA, Sars. PI. 31, figs. 43-45. 



"Widely, perspectively umbilicated, solid, semipellucid, white, 

 finely spirally lirate, crossed by close incremental stripe; whorls 3, 

 convex, moderately increasing; aperture orbicular, peristome thin. 



Diam. 1*4 mill. Arctic Norway. 



C. Verrilli, Tryon. PI. 31, fig. 46. 



Widely umbilicated, depressed, with low spire, white, finely, longi- 

 tudinally, obliquely striate, with several spiral lines on the body 

 whorl above the periphery, more numerous and closer on the base; 

 whorls 3=1, the last large, very convex, base oblique; aperture large, 

 very obliquely ovate, periphery thin and sharp. 



Diam. 2*2 mill. Off Xew Engla.nd; 545 fms. 



Described by Verrill as C. cingidatum, a specific name twice pre- 

 occupied. 



