6 CH^ENAXIS. 



1. CILENAXIS TUBA (Pilsbry & Ferriss). PL 9, figs. 1, 2, 3. 



The shell is eylindric with a short terminal cone, openly 

 umbilicate, the umbilicus nearly one-third the diameter of the 

 shell, its large cavity penetrating to the first whorl. Pale 

 brown, smooth, marked with light growth-lines. The apex is 

 obtuse. Whorls 5%, convex, the last three forming the cylin- 

 drical part of the shell; last whorl is compressed laterally 

 and obtusely angular around the umbilicus, scarcely straight- 

 ened in front; in basal view it expands broadly at the aper- 

 ture. The aperture is shortly oval, the peristome thin, con- 



Figs. 1-4. Ch&naxis tuba, type. 



tinuous and broadly expanding. The angular and parietal 

 lamellae are concrescent into one long bilobed lamella. The 

 columellar lamella is rather massive, having a sloping callous 

 or a lower rounded tooth on its lower side; becoming a low 

 cord, it continues inward to the back of the last whorl (pi. 9, 

 fig. 3). The upper and lower palatal and basal folds are 



