1915.] NATURAL SCIENCES OF PHILADELPHIA. 345 



PUPILLID^. 



Pupilla sonorana (Sterki). 



Station 11. Abundant on the summit of Big Hachet Mt. 

 Bifidaria pellucida hordeacella (Pils.). 



Stations 3, 5,^8 and 11. 



A peculiar short cylindric form, having less convex whorls, less 

 tapering spire and blunter summit, was taken at Stations 3 and 5. 



Bifidaria pilsbryana Sterki. 



Stations 8 and 11. 



Bifidaria ashmuni Sterki. 



Stations 3, 5, 8 and 11. 



VALLONIID^. 

 Vallonia sonorana n. sp. Fig. 5. 



The shell is very broadly, openly umbilicate, width of umbilicus 

 contained about three times in the diameter of shell ; Avhitish corneous. 

 First 1| whorls smooth, corneous, glossy; following whorls with 

 sculpture of rather delicate riblets about 38-40 on the last whorl, 

 in fresh .specimens bearing irregular cuticular extensions; the spaces 

 between ribs delicately striate, the striae irregularly anastomosing. 

 Whorls 3f , strongly convex, rather'slowly widening, separated by a 



Fig. 5. — Vallonia sonorana. A, type; B, thick-lipped form. 



deep suture; the last whorl deeply descending close to the aperture. 

 Aperture small, nearly circular, very oblique. The peristome is 

 expanded and reflexed, slightly thickened within (in old specimens 

 strongly thickened); the margins converge strongly and are con- 

 nected by a very short parietal callus or are continuous, joined 

 by a thin, slightly raised callus. The ample umbilicus is somewhat 

 oblong. 



