202 UROCOPTIS, S. G. GONGYLOSTOMA. 



axial lamellae, the upper one widest. It is also related to 

 Callonia, from which the weak external sculpture alone sepa- 

 rates it. The typical group of Gongylostoma (U. elegans, 

 etc.) also is allied, but here the median lamella when present 

 is short and low, and the upper one is thickened, and scarcely 

 larger than the lower lamella. The species of Liocallonia are 

 only feebly differentiated and very difficult to distinguish. 



Key to Species of Liocallonia. 

 I. Shell sculptured with thread-like rib-striae. 



1. Length 16-18 mm., with 15 whorls in truncate, 20 in 

 entire specimens; axial lamellae strong and subequal 

 in penult, whorl. U. guirensis, no. 71. 



2. Length 17, diam. 3 mm., whorls 13; obliquely costu- 

 late-striate ; 3 lamellae in median, 2 in last whorl. 



U. stearnsi, no. 72. 



3. Smaller, having spaced riblets like U. ~blainiana, but 

 riblets the color of the shell; axis 3-lamellate, the 

 upper lamella larger. U. palmce, no. 73. 



4. Length 12-13 mm., with 12-13 whorls remaining in 

 the truncate shell ; median lamella smaller in penult, 

 whorl. U. infortunata, no. 74, 



II. Shell finely striate or nearly smooth. 



1. Three subequal lamellae in the penult, whorl, viewed 

 from behind, 



a. Entire with 17-19 whorls, or narrowly truncate 

 with 13-15; length 12-14 mm.; brownish cor- 

 neous. U. brunnescens, no. 80. 



b. Truncate, with 15-17 whorls, length 14y 2 -16% 

 mm. ; pale corneous ; nearly smooth, but with 

 strong striae below the sutures. U. clara, no. 81. 



c. Truncate, with 9y 2 -ll whorls, length ll-12i/ 2 

 mm. ; very finely striate. U. propinqua, no. 82. 



2. Median lamella reduced or obsolete in penult, whorl. 



a. Lower lamella enlarged and stout in the back 

 of last whorl, and weakly emerging at the lip-, 

 shell rather widely truncate, with 12-14 whorls ; 

 length 11%-lG mm. U. vincta, no. 83. 



