VOL. XIX, PP. 87-90 JUNE 4, 1906 



PROCEEDINGS 



OK THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



IDENTITY OF EUTAMIAS PALLIDUS ( ALLEN ), WITH 



A DESCRIPTION OF A RELATED FORM FROM 



THE SOUTH DAKOTA BAD LANDS. 



BY MEKRITT GARY. 



A careful study of the chipmunks commonly known as Eu- 

 tamias minimus in the collection of the Biological Survey and 

 the U. S. National Museum has brought to light some interest 

 ing facts in regard to their interrelations and distribution. The 

 above material is rich in specimens from northern Wyoming and 

 southern Montana, and proves conclusively that Tamias quad- 

 rivittatas pallidus Allen is a valid species. A related form from 

 South Dakota Bad Lands is described as new. 



Eutamias pallidus (Allen). 



Tamias quadrivittatus pallidus Allen, Proc. Bost. Soc. Nat. Hist., XVI, p. 



289, 1874. 

 Tamias minimus Allen, Bull. Am. Mus. Nat. Hist., Ill, p. 110, 1890 (part) 



not of Bachman, 1839. 



General characters. Similar in coloration to E. minimus, but much 

 larger ; hind foot about 33 mm. (instead of 30) ; tail nearly 100 mm. 



Color. A specimen from Camp Thorne, Montana (No. 11,656, U. S. N. M., 

 July 18, 1873), agrees very well in color with early August examples of 

 minimus from Green River. Comparable chipmunks (fresh postbreeding 

 pelage) from other localities in the Yellowstone region (Powderville, Al- 

 zada, and Painted Robe Creek) have the sides more heavily washed with 

 ochraceous. 



Cranial characters. Skull relatively much larger and heavier than in E. 

 minimus, the zygomata more abruptly spreading ; anterior portion of nasals 

 broad ; audital bullae larger and more inflated. 



Measurement*. A very large female from Painted Robe Creek, Montana : 



Total length, 220; tail vertebrae, 104; hind foot, 34. Two males from the 



same locality, not fully adult: 204; 92; 32; and 205; 94; 33; respectively. 



A specimen from Powder River Basin, Wyoming, 222 ; 106 ; 34. The hind 



19 PKOC. BIOL. Soc. WASH., VOL. XIX, 1906. (87) 



