The Chipmunks of the Genus Eutamias. 205 



The summer pelage is of very brief duration, and a reexamina- 

 tion of the original Nevada City specimen (collected in October, 

 1872, by E. W. Nelson) shows that it had already begun to as 

 sume the winter pelage, which is fully developed on the tail and 

 rump, the deep rusty back of the summer pelage remaining in 

 sharp contrast. In August specimens from Nevada City the 

 rusty of the back reaches farther posteriorly. 



All of the original specimens from Blue Canon described by 

 me as macr or hab dotes and also those described later by Doctor 

 Allen were collected in June and October the latter in winter 

 pelage, the former in breeding pelage, which is the winter pelage 

 with the tips of the hairs worn off. Neither of us, as already 

 remarked, had seen the summer pelage, though at that time we 

 believed the October specimens to be in this pelage. 



The original Nevada City specimen had abnormally short ears, 

 and the ear stripes were indistinct and quite different from those 

 of the original Blue Canon specimens, the whole of the dark 

 stripe, covering the anterior two-thirds of the ear, being obscured 

 by rusty. Examination of the additional material now available 

 shows that the full development of the ear stripes is a seasonal 

 character and is only attained in the winter pelage. In this 

 pelage the posterior third of the ear is clear blue-gray, sharply 

 defined by a stripe of blackish which occupies the anterior two- 

 thirds, and is margined with rusty in front only. In summer 

 pelage the rusty spreads over the whole of the dark stripe, ob 

 scuring it and giving the ear a wholly different appearance. The 

 outer pair of pale dorsal stripes is whiter in summer than at any 

 other season. 



The excessive length of the ears, which adds much to the re 

 markable appearance of the animal, is most pronounced in the 

 Blue Canon specimens. The ears are nearly as long in the 

 Michigan Bluff specimens and only slightly shorter in those from 

 Nevada City. 



In some respects Eutamias quadrimaculatus seems to hold an 

 intermediate position between callipeplus of the speciosus group 

 and senex of the townsendi group, but in reality it is not interme 

 diate. The particulars in which it differs from callipeplus have 

 been stated (p. 202). In post-breeding pelage it resembles senex, 

 but it differs from senex in the following points : ear larger and 

 longer ; white face stripe, ear stripe, post-auricular patches, and 

 outer pair of white dorsal stripes whiter ; dark facial stripes 



47 BIOL. Soc. WASH., VOL. XI, 1897 



