CYCLOSTREMA. 91 



C. DiAPHANA, Verrill. PL 31, fig. 47. 



Narrowly umbilicated, depressed trochiform, thin, translucent, 

 white, smooth, shining; whorls 82, very convex, with deep suture, 

 smooth, except twenty to twenty-five close spiral lines around the 

 umbilical perforation. Diam. 3 mill. 



Off New England; 98 fms. 



C. DuNKERi, Tryon. PL 32, figs. 48, 49. 



Widely umbilicated, depressed, with a spiral rib near the suture, 

 another on the periphery, and a third circumscribing the umbilicus. 



Diam. 2'5 mill. Jajyan. 



Described by Duuker as C. clngulata, a name preoccupied by 

 Philippi. 



C. Philippii, Issel. PL 32, figs. 50, 51. 



Widely umbilicated, yellowish white, obsoletely radiately plicate- 

 striate, with three spiral ridges, one near the suture, the other defi- 

 ning a narrow peripheral area; whorls ?)h, rapidly increasing, flat- 

 tened above, a little convex below, umbilicus defined by a granular 

 rib. Diam. 1"5 mill. 



Suez. 



O. ciNGULATA, Philippi. PL 32, figs. 53, 54. 



Narrowly umbilicated, with radiating low, broadly rounded un- 

 dulations above, scolloping the periphery, quadricarinate in the 

 adults, bicarinate in the young, the carime being more acuate, sin- 

 uately dentate, and dotted with brown ; aperture subcircular in the 

 adult. • Red Sea. 



The only figure represents a young shell, Vb mill, in diam. 

 The size of the adult is not given. 



C. Verreauxii, Fischer. PL 32, fig. 52. 



jNIoderately umbilicated, whorls rapidly increasing, the last en- 

 circled by three keels, of which the peripheral one is most prom- 

 inent, and produced at the aperture into a tongue-shaped lobe, 

 umbilical wall flattened, defined by an angle, peristome produced 

 by the peripheral keel. Diam. 4*5 mill. 



California. 



I believe that the indefinite locality given by Fischer thirty 

 years ago remains unverified. 



