Number :o6 February i8, 1922 



OCCASIONAL PAPERS OF THE MUSEUM OF 

 ZOOLOGY 



UNIVERSITY OF MICHIGAN 



Ann Arbor, Michigan • Published by the University 



THE MOLLUSCA COLLECTED BY THE UNIVERSITY 



OF MICHIGAN-WALKER EXPEDITION IN 



SOUTHERN VERA CRUZ, MEXICO. I 



By H. Burrington Baker 



Introduction 



The specimens on which this paper is based were collected 

 by the University of Michigan- Walker Expedition, during six 

 weeks (July 10 to August 20) in the summer of 1910. The 

 expedition consisted of Alexander G. Ruthven and his wife, 

 Florence H. Ruthven, who paid particular attention to the 

 amphibians and reptiles, and the writer, w^ho was primarily 

 interested in mollusca. 



The work of identification and description was made pos- 

 sible by the Academy of Natural Sciences of Philadelphia, 

 which generously put at my disposal its extensive collections 

 and exhaustive library. As a result, any credit that this paper 

 may deserve is largely due to Dr. H. A. Pilsbry, whose con- 



