Henderson and Cockerell — Notes on the Pikas of Colorado. 121 



dark ochraceous mixed with the gray. This difference, however, 

 is not uniform. One of the figginsi has rather more of the gray 

 than one of thf saxatilis, and these two, with another somewhat 

 darker figginsi, form an almost complete series grading from one 

 form to the other. Below, the saxatilis lot is nearly white, with a 

 very light wash of huff, while figginsi has a stronger wash of 

 ochraceous hull', especially well defined along the medial ventral 

 surface, somewhat lighter in two specimens, these two being the 

 same ones that are lighter above than the other three. In the 

 ventral colors, as in the dorsal, we find an almost complete 

 gradation between the two forms. It is notable that the dif- 

 ference in the ventral surface of the two forms is the exact 

 reverse of that noted by Dr. Allen in the winter pelage. He 

 says saxatilis is "pale huff, with the pectoral hand approaching 

 ochraceous huff; in figginsi it is white with a pale yellowish 

 wash, a little stronger and more huffy on the pectoral hand, hut 

 not of the deep huff seen in saxatilis." In other words, if our 

 specimens are true figginsi and saxatilis, then the difference in 

 the ventral surface in wilder pelage is the exact reverse of the 

 difference in summer pelage. The crowns of all our figginsi are 

 much darker than in our saxatilis, and with a distinct vinaceous 

 cast. In this respect the tendency to intergrade is much less 

 than in any other respect. The following are the measurements 

 in the flesh, in millimeters, which do not help us much: 



Jenny Lake, < iilpin ( lounty, 



Jenny Lake, ' iilpin ( !ormty, 



( !orona, < iilpin County, 



( lamp Albion, Boulder ( Jounty, 



Trappers' Luke, 



Trappers' Lake, 



Trappers' Lake, 



Trappers' Lake, 



Trappers' Lake, 



We have in Colorado clearly two races. Whether they should 

 he deemed distinct species may be less certain. From the 

 evidence at hand we should call them subspecies, in which 

 event the new form should he called Ochotona saxatilis figginsi 

 (Allen). 



The chief point of interest in these two forms is that they 



