CERION, GROUP IV. 203 



C. MICRODON (Pilsbry and V a natta). PI. 28, fig. 36. 



Shell varying from cylindric to stout oval, strong and solid ; whit- 

 ish with some inconspicuous gray flecks. Whorls 8-5 to 9^, the first 

 one smooth, next finely and regularly costellate, following whorls 

 with coarser riblets becoming regular, curved and moderately coarse 

 on the cylindrical portion, somewhat narrower than the intervals, 

 and 28 to 30 in number on the penultimate whorl ; on the base of 

 the last whorl the riblets become obsolete or subobsolete. Later 3 

 to 4 whorls of about equal diameter, those above forming rather a 

 long cone with convex outlines and obtuse apex. Aperture rounded, 

 truncate above, white within. Feristome white, narrowly expanded 

 and subreflexed, obtuse ; parietal callus very thin or moderate. 

 Axial fold inconspicuous from in front; parietal tooth extremely 

 small, short. 



Length 21^, diam. 10^, long axis of aperture 9 mill. 



Length 19^, diam. 9^, long axis of aperture 8 mill. 



Length 18^, diam. 10, long axis of aperture 7^ mill. 



Cuba. 



Cerion incrassatum microdon P. and V., Proc. A. N. S. P., 1896, 

 pp. 319, 328, pi. 11, f. 5. 



The convex and obtuse terminal cone, want of color, and more 

 widely spaced and arcuate riblets, separate this species from C. tenui- 

 labre ; but the small, deeply -placed parietal lamella and the style of 

 sculpture show it to belong to the same group, and not near C. in- 

 crassatum or dimidiatum, where it was originally placed. 



C. VENUSTUM (Poey). 



Shell rimate, conic ovate, solid, glossy, elegantly sculptured with 

 close riblets ; apex rather obtuse, flesh-colored ; marbled with irreg- 

 ular oblique stripes. Whorls 9, flattened, narrow, the last ascending 

 in front, compressed at the base. Aperture ovate- oblong, fulvous 

 inside ; plica? obsolete ; peristome thickened, expanded, white, the 

 margins joined by a callus. Length 24, diam. 10 mill.; longest 

 axis of aperture with peristome 11, width 9 mill. (Poey). 



Cuba (Dr. D. Regino Perez). 



Pupa venusta POEY, Memorias, ii, p. 30 (18,56-1858). PFR., 

 Monogr., iv, p. 659. 



There are 56 riblets on the last entire whorl. It resembles the 



