96 



PROCEEDINGS OF THE ACADEMY OF 



[March, 



On the west slope of the Black Range there are two forms: (1) 

 in the south, 0. m. concentrica, broadly umbilicate, with low, wide 

 spiral cords on the base, and (2) further north, 0. m. radiata, with 

 strong radial sculpture, remarkably like 0. eirodi. On the eastern 

 slope we have (3), southward, 0. m. acutidiscus, broadly umbilicate, 

 with fine spiral and coarser radial sculpture, and (4) further north, 

 0. hermosensis, nearly smooth, angular only in front. Still further 

 north a few "bones" of typical metcalfei were found, acutely keeled 

 throughout and nearly smooth. Northeast of here was found 

 0. m. cuchillensis, which is so weakly angular that we at first thought 

 it a form of 0. strigosa depressa. Further west 0. pilshryi was found. 

 Further north, in Socorra County, there is 0. socorroensis, an angular, 

 roughly sculptured shell, as yet known only by perfectly bleached 

 "bones." 



The metcalfei group therefore comprises, besides the original type,, 

 forms resembling 0. haydetii, 0. eirodi and 0. strigosa depressa; each 

 being alone in its district. The distribution may be represented 

 diagrammatically thus : 



pilsbryi i^ 



cuchillensis -^ 



■^ metcalfei 



if hermosensis 



radinta ir 

 concentrica ir 



if acutidiscus 



Diagram to show localities of the races of Oreohelix metcaljei relative to one 

 another and to the crest of the Black Range from Sawyer to Diamond Peak. 

 Scale about 16 miles to an inch. 



