32 STROBILOPS, MEXICO, CENTRAL AMERICA. 



Indiana (L. E. Daniels, 1905). Koanoke, Randolph Co., and 

 Lookout Mountain near Valley Head, Alabama (H. H. Smith). 



Species of Mexico and Central America. 



All of the Mexican species except S. huhhardi belong to the 

 group of S. streheli, in which there is a small columellar 

 lameUa and three hasal folds; na folds above- the periphery, 

 such as occur in the lahyrinthica group. Tliis Mexican group 

 includes also the northern 8. conea and all of the South Amer- 

 ican species now known, except perhaps S. helleri. 



In 8. veracruzensis crossei the internal barrier has not been 

 examined ; probably it conforms in this respect to other conic 

 Nootropic species. In 8. csnea there are usually four basal 

 folds, a minute one appearing between the second and third 

 larger folds. 



Key to 8pecies. 



1. Form subdiscoidal, the height about half the diameter; 



umbilicus contained 3 to 4 times in diameter. 



8. huhhardi, No. 15. 

 Form low-conic (2). 

 Form elevated, trochiform, the height 80 to 90 per cent of 



the diameter (3). 



2. Umbilicus contained 5 to Si/o times in diam. 



8. (vnea mexicaim, No. 4c. 

 Umbilicus contained 10 to 12 times in diameter. 



8. streheli, No. 5. 



3. Umbilicus large, contained 3 to 4 times in diameter; shell 



carinate, diam. 3 mm. 8. salvini. No. 7. 



Umbilicus small, about 10 times in diameter; shell smaller, 

 subangular, with rather widely spaced ribs (4). 



4. Diameter about 2 mm. ^S'. veracruzensis. No. 6. 

 Diameter 2.5 to 2.8 mm. 8. v. crossei, No. 6a. 



4:C. 8trohilops cenea mexicana new subsp. PI. 5, figs. 9-13. 



Umbilicus contained 5 to 5i/2 times in the diameter, thus 

 far larger than in 8. streheli, and somewhat larger than in 

 8. ccnea. There are tliree basal folds, a short one and two 



