254 VniversUy of ('aJifornia Publications in Zoology. [Vol.7 



Ears and face of infernicditts are very much paler. In pauper- 

 rimus these parts are brown. The majority of our series have 

 silvery white coloration ventrally, while the two topotypes of 

 pauperrimus have the underparts pale huffy (suffused in no. 

 78535; suggested in no. 7853-4). Two females of intermedins 

 (nos. 7968, 7972) have a very slight wash ventrallj^ of the palest 

 possible buft'y. 



Although external measurements are much the same, the 

 advantage in the matter of average size lies with intermedins. 

 The type specimen (no. 7973) is the only one of our series having 

 a hind foot measuring 18 millimeters. The measurement in the 

 dry skin is 16.8, and I am inclined to think the recorded measure- 

 ment a little too large. 



The skulls of intermcdius, with the exception of that of no. 

 7973, which is flat-topped, present a slight concavity postorbitally 

 very similar to pauperrimus. With the exception of the zygo- 

 matic breadth the skulls of iniermedius are slightly larger than 

 that of an adult female pauperrimus figured by Bailey (1900, p. 

 70). On the same page of his Revision, Bailey calls attention 

 to the fact that a single specimen of supposed pauperrimus from 

 the top of Steen Mountain, Harney County, Oregon, is not typi- 

 cal. This specimen is now before me. It is a female (no. 79917) 

 taken July 24, 1896, by C. H. Merriam and Bailey. It measures, 

 total length, 121 mm.; tail vertebrae, 24; hind foot, 18. Thus in 

 dimensions this specimen is almost identical with the average for 

 intermedins. It has the lower x>arts white, with a slight wash of 

 buffy, more as in pauperrimus. It also exhibits the brownish 

 doi'sal coloration which at once distinguishes pauperrimus from 

 intermeelius. The face and ears are distinctly brownish, unlike 

 the Nevada specimens. The Steen jMountain animal is also some- 

 what paler than the two examples of pauperrimus from Antelope; 

 but whether this is significant of an intermediate condition may 

 be doubted, for no. 79!)17 has evidently assumed the post-breeding 

 pelage, which is lull and long. The topotypes are still in the 

 breeding dress, wliicli is woi-n so that the plumbeous bases of the 

 hairs show through both dorsally and ventrally. However, this 

 aberrant specimen (no. 79917), although nearer pauperrimus, 

 does very clearly show characters somewhat intermediate between 



