50 HELIX. 



H. PRESSULA, Morelet. PI. 5, figs. 4, 5. 



Openly umbilicated, thin, translucent, minutely granulose, 

 corneous, with a dark brown band; suture deep; whorls 4^, 

 the last deflected in front, base convex ; aperture obliquely 

 lunar, margins approaching. Diam. 10 mill. 



Pacific Shore of Guatemala. 



H. OAJACENSIS, Koch. PL 5, figs. 6, 7. 



Rather widely umbilicated, obliquely roughly striate, lightly, 

 very minutely granular, obtusely carinate, brownish corneous, 

 with two yellowish bands, one superior, the other at the carina ; 

 whorls 4J, scarcely convex ; aperture Innately subcircular, 

 brownish within, with two white bands. Diam. 15 mill. 



Oajaca, Mexico. 



H. OBSITA, Pfr. (unfigurecl). Mexico. 



Subsection THYSANOPHORA, Strebel and Pfeffer. 

 H. IMPURA, Pfr. PL 5, figs. 8-10. 



Moderately umbilicated, rather thin, rugosely costulate, 

 slightty spirally striate, corneous, suture deep; whorls 5, the last 

 one subdepressed, not descending, base costulately striate. 



Diam. 4 mill. 



Mirador, Vera Cruz, Mexico. 



H. PALEOSA, Strebel. PL 5, figs. 11-13. 



Shell umbilicated, rather solid, shining, reddish brown, ru- 

 gosely costulate, with microscopic spiral lines ; whorls 5, the 

 last spread out, with flattened base, so that the periphery 

 appears indistinctly angulated, and the umbilicus is narrower, 

 with steeper walls than in H. impura. Diam. 4'5 mill. 



Forest of Pacho, Mexico. 



H. CONSPURCATELLA, Morelet. PL 5, figs. 14-16. 



Widely umbilicated, scarcely convex above, turgid below, 

 membranously striulate, corneous, suture deep ; whorls 3-4, the 

 last subdilated in front, angulate above the periphery. 



Diam. 3*5 mill. 



Merida, Yucatan; Guatemala. 



