588 Bulletin American Museum of Natural History. [Vol. XIX, 



inhabiting the southern border of Arizona, but careful com- 

 parison, with the aid of abundant material, shows that such 

 reference would in most cases fail to express their true 

 relationships. 



I am indebted to the kindness of Dr. A. K. Fisher, Acting 

 Chief of the U. S. Biological Survey, and to Mr. Gerrit S. 

 Miller, Jr., Assistant Curator of Mammals, U. S. National 

 Museum, for the loan of topotypes of various species for use 

 in the present connection. 



[NOTE. The measurements taken by the collector from the fresh 

 specimens are as follows: (i) Head and body; (2) tail vertebras; (3) 

 hind foot, measured to end of longest toe (after the British Museum 

 method), and hence not including the claw; (4) ear, measured from 

 the notch instead of from the crown, except in a few cases, as in the 

 hares, where both are often given. For convenience in comparison 

 the total length is here also given, made up by adding the collector's 

 first two measurements.] 



I. DONNA ANA COUNTY, NEW MEXICO. 



The specimens here recorded, about 150 in number, were all 

 taken during the month of December (Dec. 626), along the 

 southern border of Donna Ana County, a little west of El 

 Paso. 



i. Citellus (Otospermophilus) grammurus (Say). 



One specimen, collected at Chamberino. "Not common." 



2. Peromyscus tornillo M earns. 



Ten specimens: Guadalupe Ranch, i, Dec. 3; La Mesa, 8, 

 Dec. 13-17; Chamberino, i, Dec. 26. 



Seven adults (4 males and 3 females) measure as follows: 

 Total length, 169 (163171); head and body, 93 (9095); tail 

 vertebras, 75.5 (73-76); hind "foot (without claws), 20.6 

 (19-22); ear, 18.1 (18-18.3). 



3. Sigmodon hispidus berlandieri (Baird). 



Nine specimens, collected as follows: Guadalupe Ranch, 4, 

 Dec. 13-16; La Mesa, i, Dec. 19; Chamberino, 4, Dec. 26. 



