OJ 



PROCEEDINGS OF THE ACADEMY OF 



[Feb., 



moderately in front, and is well rounded on periphery and base, as 

 usual. The aperture is large, oblique, rounded, nearly as high as wide. 

 Peristome thin, narrowly expanded outwardly, the basal margin a 

 trifle reflexed, columellar margin dilated in a curved triangular plate 

 over about one-third of the umbilicus. Alt. 14, diam. 23 mm.; aper- 

 ture, alt. 12, diam. 13 mm. 



Buck erf C« 



Bio Cmi&ikakt Cn 



TC 



Tail Cn. 



Fig. 2. — Distribution of Sonorella in the Chiricahua Mountains: 1, S. bicipitis; 

 2, S. bounensis (at point of the arrow); 3, »S. optata; 4, >S. micra; 5, S. virilis 

 leucura; 6, S. virilis; 7, »S. binneyi. Large areas between 1 and 2 and between 

 3 and 4 are unexplored. 



