CER10N, GROUP VIII. 231 



VIII. Group of 0. regina. 



Strophiops DALL, Bull. M. C. Z. xxv, no. 9, p. 121, type C, 

 regium. 



The shell is usually rather large, cylindric or column- shaped, vary- 

 ing from smooth to ribbed. The umbilical rima is usually long, often 

 perforate, and there is a large excavated area behind the columellar 

 lip. The aperture is rather long, peristome expanded and reflexed, 

 but its face is not thickened or built forward. Parietal tooth varies 

 from a third of a whorl long to short. The parietal callus may be 

 heavy, but does not form a raised ledge. The young, in C. regina^ 

 have an open, trapezoidal aperture with no teeth except a small colu- 

 mellar plait. The species are from the southeastern Bahamas. 

 This group is closely allied to the Cuban group of C. mumia. 



1. Species of Turk's Island : C. regina and varieties, C. incanoides. 



2. Species of the Inagua group : C. calcareum, C. sarcostomum, C. 

 columna. . . 



3. Species of the Crooked Island group and Long Island: C. 

 regium. Castle Island. C. weinlandi, Crooked Island. C. inflatum, 

 Acklin Island. C. nudum. Long Island. 



The several forms from each island group are very closely related. 

 The variation in sculpture in C. columna and regina is extraordinary. 

 Species of the third sub-group are smooth or nearly so. 



C. REGINA Pilsbry & Vanatta. PI. 35, figs. 27, 28, 29, 30. 



Shell thick, subcylindrical, gradually tapering above, the long 

 terminal cone passing gradually into the cylindrical portion; lower 3 

 whorls of about equal diameter; apex obtuse; earlier whorls not 

 striate; chalk-white and dull, the smoothness of the surface but little 

 broken by slight growth-lines, the basal whorl irregularly and rather 

 distantly costate, at least on its latter half. Whorls 10 to 10^, flat, 

 with superficial seam-like sutures. Last whorl suddenly ascending in 

 front, much compressed and pinched toward the base. Umbilicus 

 open or perforate, with the usual arcuate rima, below which it is 

 broadly excavated and flattened. Aperture oblong-cordate, slightly 

 less than one-third the length of shell, higher than wide, dark or 

 light brown within, rarely purplish. Peristome expanded and re- 

 flexed, its face convex but not much thickened, whitish, parietal 

 callus moderate, its outer edge not raised. Axial lamina situated 



