MUSEUM OF COMPAllATIVE ZOOLOGY. 393 



above and below. Umbilicus deep, scalar, not very wide, with vertical walls, 

 vertically striate, and sonietinies with a few spiral grooves; aperture trans- 

 versely ovate, margins simple, sharp; epidermis thin, yellowish, conspicuous 

 only on the carinic. Max. diam., 3.0; alt., 1.5 mm. 



Habitat. Off Ilatteras, in 15 fms., U. S. Fish Commission. Florida, Stimp- 

 son and Jcwett. 



This species differs from V. gemma Holmes, in being more depressed and 

 having more keels. It is also smaller. 



Genus CYCLOSTREMA Marryat. 



Several species of this group are found in the western part of the Atlantic, 

 though for the most part in the cooler area. Among them are C. trochoides 

 Jeffreys, which has received the name of C. affine from Prof. Verrill. A care- 

 ful comparison of types leaves no doubt as to the identity of these two forms, 

 for which Jeffreys's name has precedence. 



Of the identity of Cyclostrema diaphanum Verrill (1884) with C. {Trochus) 

 fulgidus Jeffreys (1883), as claimed by Dr. Jeffreys, I am not at all satisfied. 

 All these small shells are very similar, but so far as they have any characters 

 these two would appear to differ. On the other hand, C. Dalli Verrill (de- 

 scribed in 1880) is extremely close to and probably identical with C. fulgidus. 

 C. Dalli var. ornatum Verrill would appear to be a good species, and possibly 

 may be a Mollei-ia, as a specimen I have from near Cape Fear shows a shelf, 

 as if for the thick operculum, inside the extreme margin. 



A few interesting species can be added to the list, though some doubt at- 

 taches to the generic reference in the absence of the soft parts and operculum. 



Cyclostrema turbinum n. s. 



Plate XXXIII. Fig. 5. 



Shell small, thin, subconic, with four rounded whorls and a minute glassy 

 nucleus; radiating sculpture of fine oblique incremental lines, which on the 

 early whorls rise into very fine threads, visible crossing the interspaces of the 

 spiral sculpture; spiral sculpture of (on the last whorl) about seven strong 

 smooth even cinguli on the top of the whorl, and fourteen or fifteen more 

 rather smaller fr(jm the periphery to the brink of the umbilicus; there are 

 also a few finer ones, especially three near the suture, and occasionally some 

 spiral striation faintly indicated; on the top of the whorl the interspaces are 

 about twice as wide as the threads, but not so wide on the base. The whorls, 

 periphery, and base are evenly rounded, the suture distinct, not channelled; 

 the umbilicus perforate, with smoothish walls; aperture half as high as the 

 shell, oblique, nearly circular, with sharp, simple, slightly expanded edges. 

 Max. diam., 3.25; alt., 2.75 mm. 



Habitat. Off Havana, in 80 fms., Sigsbee. 



