PRESTON : JIOLLUSCA FROM N.W. CHINA. 15 



and very oblique, and below which is situated a small, twisted, basal 

 plication ; a thin, elongate, revolving lamella is also visible on the 

 outer wall, but situated well within the shell. Alt. 42 mm. ; diam. 

 m;ij. 10, unii. 8-75 ram. Aperture: alt. 8, diam. 5-5 mm. 



Ilab. — From the Loess Plain of the Wei lUver, S. Shen-si, at an 

 altitude of 1,200 feet. 



