COELOCENTRUM. 35 



C. pfefferi BALL, Proc. U. S. Nat. Mus. xix, p. 352, pi. 33, 

 f. 1, 2 (Jan. 27, 1897). v. MART., Biol., p. 634. 



This species is shorter, stouter, and less cylindrical than C. 

 turns, Pfeiffer, which has proportionally more numerous 

 whorls, and is smaller and more fusiform than C. Nelsoni. 

 It is respectfully dedicated to the distinguished naturalist of 

 Hamburg, Dr. G. Pfeffer, well known for his work on Mexican 

 land shells in conjunction with H. Strebel. (Dall) . 



C. NELSONI Dall. PL 11, figs. 8, 9. 



Shell large, strong, decollate, retaining 9 whorls, subcylin- 

 dric, attenuated more rapidly at the upper 2 or 3 whorls, 

 periphery flattish, suture distinct, strong, not deep; trans- 

 verse sculpture of numerous rather asperate concavely arched 

 little raised ridges, stronger near the sutures and usually with 

 wider interspaces; spiral sculpture of somewhat vermicular 

 obscure character like the markings left by a " sand-blast," 

 but occasionally developing sparse distant fine spiral riblets, 

 and stronger on the later whorls ; base rounded except for the 

 obscure peripheral line, the umbilicus almost closed ; aperture 

 rounded below, slightly angular, oblique, free from the body 

 whorl, with the margin continuous and reflected but narrow; 

 axis normal, nearly closed at the decollation where it is small, 

 but large in the latter whorls; color pale straw. Length 53, 

 maximum diameter 18, diameter at decollation 8 mm. (Dall). 



Tuxtla, Mexico. (V. W. Nelson) ; type No. 107368, U. S. N. M. 



C. nelsoni DALL, Proc. U. S. Nat. Mus. xix, p. 352, pi. 33, 

 f. 5, 6 (Jan. 27, 1897). 



" This shell recalls Eucalodium compactum Pilsbry, but is 

 more cylindrical and stouter, besides having a totally different 

 axis. It is the largest known species of the genus, and is dedi- 

 cated to the indefatigable naturalist E. W. Nelson, who has 

 added so largely to our knowledge of the American fauna 

 from Alaska to Guatemala." Dall. 



C. ANOMALUM Strebel. PI. 9, figs. 6, 7. 



Shell rather transparent, almost lustreless, as if breathed 

 upon, and of a violet-chocolate-brown color, changing to more 

 yellowish towards the summit. The lower half of the last 



