1919.] natural sciences of philadelphia. 205 



Explanation of Plates 



(Note: The illustrations on Plate IX are from photographs by the author. 

 The specimen figures on Plate X were prepared by Mr. John Howard Paine.) 



Plate IX. — Fig. 1. — St. Mary Lake and Going-to-the-Sun Mountain from 

 Going-to-the-Sun Chalets. Station V is in the woods above the Lake in the 

 right foreground. 



Fig. 2. — McDermott Lake, Mount Wilbur, Upper Swiftcurrent Valley, and 

 the Continental Divide, from near the lower end of McDermott Lake. Station 

 IX is in the woods beyond the tepees in the right center. Station XII is at 

 the far upper end of the valley around the mountain shoulder at the left of the 

 picture. Station XI is high up at the base of the steep glacial cirque in the 

 distance to the right of Mount Wilbur. 



Fig. 3. — Iceberg Lake. Station XI is a small pool a few rods from where the 

 picture was taken. 



Plate X. — Oreohelix cooperi apiarium n. subsp. Series of nine specimens 

 from the type locality, Station XVI, Cat. 3613 (excepting the type). Berry Col- 

 lection. The type (Cat. 4130) is the shell shown in Fig. 2-2b. AH figures nat- 

 ural size. 



