536 



PROCEEDINGS OF THE ACADEMY OF 



[Dec, 



but yet, except at Galveston, where it may be imported, it seems to be- 

 absent from the very wide and low Gulf border. 



Fig. 1. — Distribution of Polygyra dorfeuiUiana Lea, known localities represented 



bv dots. 



The variety sampsoni Wetherby, by its more uncoiled spiral, is a 

 more evolved or accelerated race than typical dorfeuilliana. It occu- 



