294 SPIROSTEMMA. 



Spirostemma with a good deal of doubt, as the basal keel is 

 not mentioned in the description, though shown in the figure. 

 It is 13 nun. long. 



Group of S. tenella. 



False umbilicus large as seen in the aperture from the base. 



I. Last whorl built forward carrying the aperture free of the 



preceding; length 20-23 mm. 8. elatior, no. 12. 



11. Peristome either adnate above or barely free; basal area 

 very small; shell smaller. 



1. Aperture contracted by a callous nodule on the 

 parietal wall near the columella. 



S. abnormis, no. 14. 



2. No parietal nodule. 



a. Length 10-12 mm*, whorls 9-13. 



8. tenella, no. 13. 



b. Length 7-9 mm. 8. tenera, no 13a. 



c. Length 6 mm. ; whorls 7-8. S. pusilla, no. 15. 



12. S. ELATIOR (C. B. Adams). PL 37, figs. 80, 81, 82 r 83, 94. 

 "This is also a larger shell than C. dunkeri, thicker, and 



strongly striated, with the whorls more planulate; it is much 

 longer and more slender than C. rubra. Length .93 inch, 

 breadth .13 inch [23.2x3.2 mm.] (Adams). 



Jamaica: Westmoreland (Adams). 



Cyl. elatior C.B.A., Contrib. to Conch, no. 9, p. 167 (April, 

 1851). PFR., Monogr., iii, p. 580. BLAND, Ann. Lye. N. H. 

 of N. Y., vi, p. 150, pi. 5, f. 19. 



This is an almost exactly cyUndric shell except that the 

 upper fourth or less of the length tapers. It is roseate, 

 with the whorls barely convex, almost flat, the last one acutely 

 carinate as usual, and shortly built forward. The aperture 

 is decidedly oblique, very shortly or roundly oval, the lip 

 old Isabella tinted. The axis is very strongly spiral through- 

 out the greater part of the shell, "like a spiral stairway con- 

 structed with a conical well-hole instead of a column." 

 This central well may be seen as a large hole by looking into 

 the aperture from below, as in 8. tenella. Specimens meas- 

 ure, 20.7 x 3 mm., whorls 13V 2 ; 19 x 3 mm., whorls 12. 



