254 TORN ATELL ARIA. 



Key to species of Tornatellaria. 



a. In adult specimens the diameter less than 60% of the length. 

 b. Adult shells with more than 7 nearly flat whorls, 

 c. Parietal lamella more than 0.3 mm. in height. 

 d. Parietal lamella not eroded in front, out- 

 lines of spire scarcely convex. 



e. Base somewhat flattened, shell 

 glossy. T. umbilicata, no. 6. 



e 1 . Base tapering, shell not glossy. 



T. cincta, no. 8. 



d 1 . Parietal lamella eroded in front, outlines 

 of spire slightly convex. 

 e. Wider, 4.4 x 2.6 mm. 



T. sykesii, no. 11. 

 e 1 . Narrower, 4.4x2.4 mm. 



T. convexior, no. 12. 

 c 1 . Parietal lamella less than 0.3 mm. in height. 



d. Parietal lamella more than 0.2 mm. in 

 height. 



e. Umbilicus very minute, less than 

 1/15 diam. of the shell. 



T. henshawi, no. 10. 

 e 1 . Umbilicus %-l/10 diam. of the 

 shell. 



/. Periphery encircled by a 

 broad light zone. 



T. s. illibuta, no. lla. 

 7 1 . Periphery not encircled by a 

 broad light zone. 



T. trochoides, no. 7. 



d 1 . Parietal lamella less than 0.2 mm. in 

 height. 



e. Base slightly flattened, outlines of 

 spire slightly convex. 



/. Only the upper columellar 

 lamella emerges ; umbilicus 

 contained about 6% times in 



