Mammals 53 



one-half in princeps. The fossil Paramys delicatior of Leidy, 

 found in the Eocene of the Huerfano Basin, is referred to the 

 Dipodoidea by Miller and Gidley. 



Our representative of the Hystricoidea is the porcupine, 

 Erethizon epixanthum of Brandt. It is a common animal in our 

 mountains, well protected from most predatory animals by its 

 quills. Swenk in 1916 described a new subspecies, E. e. bruneri, 

 from Scotts Bluff County, Nebraska. Compared with typical 

 (Californian) E. epixanthum, it was found to be slightly larger 

 with the hind feet comparatively shorter, the color paler and 

 duller, the under side of the tail largely or wholly brownish 

 yellow, and the skull showing some peculiarities. It appears 

 that this subspecies occurs also in Kansas, Wyoming, and Mon- 

 tana, but whether in Colorado, is not stated. The skull figured 

 by Warren appears to agree well enough with true epixanthum. 



The Lagomorpha include two very distinct superfamilies, 

 the Leporoidea or rabbits and hares, and the Ochotonoidea or 

 Pikas. The pikas (Ochotona)* occur in North America, northern 

 Asia, and eastern Europe, inhabiting rocky places. There is 

 practically no tail, and the ears have a nearly circular outline. 

 In Colorado we find them at high altitudes, especially above 

 timberline, where their sharp cries seem to come from nowhere 

 in particular, the animals at first not being observed. 0. saxa- 

 tilis of Bangs is distributed through the more eastern ranges of 

 Central Colorado, from Wyoming down to Pike's Peak, and 

 westward to the San Juan Range and even into Utah. It also 

 occurs in the Sangre de Cristo Mountains. 0. s. figginsi of 

 Allen was described from Pagoda Peak. It occupies the moun- 

 tains west of the central and northern part of the range of saxa- 

 tilis, and is isolated from it by valleys. The colonies of saxatilis 

 on the Sangre de Cristo, Pikes Peak, etc., are also isolated, but no 

 distinctive peculiarities have been reported. It is said of figginsi 

 that it is smaller, with the color darker and more vinaceous. 

 Nevertheless, the characters of the two races vary, so that in- 

 dividual specimens are intermediate. Howell refers both to 0. 

 princeps, described from Alberta, as subspecies, but this is per- 

 haps going too far. If we treat 0. saxatilis as a species, the New 

 Mexico (Pecos Baldy) incana will be 0. s. incana, as Howell 



*Howell, Revision of the American Pikas. North American Fauna, No. 47 (1924). 



