200 



PROCEEDINGS OF THE ACADEMY OF 



[Oct., 



darker bands, one on the shoulder, the other just below the periphery, 

 with sometimes a broader Hght band between, and several weaker 

 and narrower bands below extending upon the base of the shell. 

 Entirely bandless specimens seem to occur but rarely. 



Fig. 1. Orcohclix cooperi apiarium new subspecies. Apical and basal views of 

 shells of unborn young, taken from specimen shown in PI. X, Fig. 2- 2b (type). 

 X13. 



The embryonic shell is lenticular in outline and strongly carinate 

 as usual in the genus. It is sculptured with numerous very fine, 

 crowded, wavy, spiral striae, crossed on the neanic portion by coarser, 

 but still narrow, rather irregularly spaced, wrinkle-like, incremental 

 ridges, some of them eventually becoming almost rib-like above, 

 but practically obsolete below the periphery, where, however, the 

 fine spiral striation is in these young specimens beautifully developed. 



Largest from Smallest Adult Largest, 



Station XVI Station XVI Station XV 



Maximum diameter 22.0 mm. 15.6 mm. 23.2 mm. 



Minimum diameter 2L3 mm. 15.1 mm. 20.3 mm. 



Altitude 19.6 mm. 15.4 mm. 18.0 mm. 



Diameter of umbilicus 3.5 mm. 2.5 mm. 3.7 mm. 



Number of whorls 6V3 6 6 



Illustration, Plate X Figs. 2-2b Figs. 7-7b 



Type. — Cat. No. 4130 of the writer's collection; paratypes in The 

 Academy of Natural Sciences of Philadelphia, the University of 

 Colorado Museum, and the California Academy of Sciences. 



Type Locality. — Station XVI, altitude 3550 ft., McDonald Creek 

 Canyon, opposite Glacier Wall, Granite Park Trail, Glacier National 

 Park, Montana; 37 specimens. 



