PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 67 



and one-half turns we again have ribs appearing, but these ribs are 

 hirge, broad, rough, and rather ill-defined. Suture moderately 

 impressed. Periphery of the last turn, which is rather high, marked 

 by a very strong carina with a pinched-in area immediately above 

 and below it. The basal wall sloping to the umbilical chink is marked 

 by numerous, rough, slightly lamellar ribs. There are here also 

 some indications of spu'al sculpture. Aperture moderately large, 

 more or less triangular, with a broad, expanded and reflected, wide 

 peristome which is free. The summit of the free portion of the last 

 whorl forms a strong carina. The outside of the free portion of the 

 parietal wall is marked by the continuation of the axial ribs. 



The type. Cat. No. 361964, U.S.N.M., was collected east of Mon- 

 clova, Coahuila, Mexico. It has 17 whorls and measures: Length 

 22.1 mm.; diameter, 5.3 mm. 



Twenty-four additional specimens, Cat. No. 361965, U.S.N.M., 

 yield the following measurements: 



•Type. 



Another lot, Cat. No. 361966, U.S.N. M., taken at an altitude of 

 3,000 feet, about halfway between Nueva Leon and Monclova, 

 Coahuila, Mexico, appears to belong to this species. Twenty-four 

 specimens of this lot yield the following measurements: 



