COELOCENTRUM. 37 



the last shortly free in front, the pale-colored convex base 

 defined by a low cord, while a stronger, arcuate keel at the 

 base defines the umbilical area. Aperture rounded, oblique, 

 the peristome continuous, white, rather broadly reflexed 

 throughout. Internal column large (6 mm. diam. in a shell 

 of 14 mm. diam.), conspicuously bulging, the greatest con- 

 vexity 'at about the lower third in each whorl; sculptured with 

 rather wide-spaced, obliquely longitudinal, low lamella}, which 

 are highest on the convexity, and mostly do not run below it. 

 These lamellas are somewhat irregularly spaced, and irregular 

 at the free edges, and there are some granules scattered on 

 the polished surface of the pillar. 



Length 55, diam. 14 mm. ; whorls 16. 



Length 68-72, diam. 14 mm. (Pfr.). 



Chiapas, in southeastern Mexico (Ghiesbreght). 



Cylindrella turns PFR., P. Z. S. 1856, p. 380, pi. 36, f. 2; 

 Mai. Bliitt. 1856, p. 217 ; Conchyl. Cab., p. 35, pi. 8, f . 20, 21 ; 

 Monogr. iv, p. 695; vi, 365 BLAND, Ann. Lye. Nat. Hist, of 

 N. Y., viii, p. 160. SOWERBY, Conch. Icon, xx, pi. 13, f. 117. 

 Eucalodium turris CROSSE & FISCH., Journ. de Conchyl. xvi, 

 p. 88 ; xviii, p. 22. Ccclocentrum turris FISCH. & CROSSE, 

 Moll. Mex., i, p. 345, pi. 15, f. 13. STREBEL, Beitrag, iv, p. 

 56, pi. 5, f. 18; pi. 14, f. 2 A, B. v. MARTENS, Biol. Centr. 

 Amer., Moll, p. 270. 



Thin and light for a shell of its size. It differs from other 

 large species by the greater number of whorls preserved in 

 the adult shell. ' ' Varies in the length of the adult shell from 

 59-72 millim., and in the breadth of the penultimate whorl 

 from 12i/o-14 millim. Number of preserved whorls 16-24. 

 The variation in the length of the adult shell does not depend 

 entirely upon the number of preserved whorls; I have before 

 me a specimen measuring 61 millim. with 16 preserved whorls, 

 and another of 60 millim. with 19 preserved whorls. The 

 greater the number of preserved whorls, the more strongly is 

 the shell attenuated upwards. 



" The figures in Reeve's Conchologia Iconica, 77 millim. 

 long, represents a specimen with an unusually large number 

 of preserved whorls, viz., 27." (v. MART.) 



