122 Psyche [August 
haps it should be regarded merely as a subspecies of aldrichi, but 
its exact status can be determined only with the aid of additional 
material and with specimens of the males and females of both forms. 
Further researches in the mountains of the northwest will prob- 
ably bring to light additional species of Oreomyrma. The number 
and distribution of those at present known indicate that the 
Rocky Mountains are the center of distribution of the subgenus 
and that M. rubida may have reached the Old World during the 
Tertiary by way of the Behring Strait land-bridge. 
ine.e*: 
ae 
Fig. 1. a, Thorax and pedicel of Myrmica (Oreomyrma) rubida Latr. in profile; 
b, of M. (0O.) aldrichi sp. nov.; c, of M. (O.) hunteri sp. nov.; d, of M. (O.) mutica 
Emery; e, of M. (O.) bradleyi Wheeler. 
