184 UROCOPTIS, S. G. GONGYLOSTOMA. 



somewhat out of proportion, in order to show the number of 

 spiral lamellae. Thus, Pycnoptychia is really as near as 

 Esochara to the elegans group in structure In the concreta- 

 elegans-Liocallonia series there is practically no modification 

 in texture, form or onamentation externally. 



In a number of groups, two parallel series of species, finely 

 striate and spaced rib-striate or costulate, exist. This is espe- 

 cially noticeable in the group of U. elegans and phyla radi- 

 ating therefrom. 



Key to Sections of Gongylostoma. 



I. Lower axial lamella expanding into a broad, flat or cup- 

 shaped plate, in an intermediate whorl. Western Cuba. 



Section Esochara, no. 58-60. 



II. Two subequal axial spirals, the cavity of an intermediate 

 whorl contracted by accessory lamellae upon the parietal, 

 basal and usually the outer walls. Eastern Cuba. 



Section Sectilumen, no. 57. 



III. Intermediate whorls without such special modifications 

 of the lamellae. 



1. Shell small, pale, with nodose suture and fine, inter- 

 lacing striae; truncate, the rejected portion long, 

 attenuate, with costulate apical whorls. Axis with 

 one spinose lamella. Eastern Cuba. 



Section Fibriciitis, no. 56. 



2. Rather large, uniform brown or corneous-brown; 

 axis with 3 to 8 spiral lamellae, increasing in size 

 from the upper to the lowest, which is widest; re- 

 jected portion of spire short, not attenuate, apical 

 whorls smooth; aperture not dark within. 



Section Pycnoptychia, no. 61-66. 



3. Axis with 3 thin spiral lamellae, the upper widest, 

 lower smallest in intermediate whorls ; shell slender. 



a. Shell sculptured with large, hollow ribs, very 

 slender and many-whorled, attenuate above, 

 whorls 30 to 40 in entire shells. 



Section Callonia, no. 69, 70. 



