MAMMALS OF THE MEXICAN BOUNDARY. 801 



Wiis last seen about 1(» miles west of Jacuniba Hot Sprinus, in lock}- 

 hills bordering)- a canyon near the Hayden ranch. On the phiin called 

 Jacumba Flats the antelope oround-squirrel was very numerous, living- 

 on level ground, dig-gino- its ])urrows under sagelirush, much as Citellus 

 feretlvdiKhis does; but in the canyon at the head of Jacuni])a Creek it 

 lived in the most rugged mountain sides. When running, its tail is 

 always carried vertically; and it continually utters a trilling call that 

 sounded on the ear from vai'ious distances all through the daj's spent 

 in camp at Mountain Spring. The large cheek-pouches of those killed 

 were alw^ays found to contain seeds or green vegetation. Sometimes 

 it is veiy shy and seldom seen, while at other times it appears in 

 abundance and is very tame. Mr. Holzner made the following note: 



At ■Mountain Sjnin-;, California, in May, 1894, 10 small young indivitluals of uni- 

 form yize were caught from one hole. The mother was never seen; and, as the place 

 was very near the rock house (occupied l)y soldiers) and my tent, she could not have 

 l)assed in and out unnoticed. Did she have sufficient food in her nest, or did she 

 forage at night? 



AMMOSPERMOPHILUS LEUCURUS INTERPRES (Merriam). 

 EL PASO GROUND SQUIRREL. 

 Tmni'is inlerpres Merriam, North American Fauna, No. 4, Oct. 8, 1890, p. 21 



( original description ) . 

 Spermopltilus interpret, Bkvant, Zoe, III, Oct., 1892, p. 208. — Miller and Rern, 



Proc. Bost. Soc. Nat. Hist., XXX, No. 1, Dec. 27, 1901, p. 51 (Syst. Results 



Study N. Am. Mam. to close of 1900) . 

 ISperinopliilns] mterpres, Elliot, Field Col. Mus., Zool. 8er., II, Mar., 1901, p. 86 



(yynop. 31am. N. Am.). 

 ]_Oitellus] mlerjires, F.lliot, Field Col. Mus., Zool. Ser., IV, 1904, p. 143. 



Type-lomUty. — El Paso, Texas. (Type, skin and skull, No. H^li? 

 U. S. National Museum, Biological Survey Collection.) 



GeograpltlcaJ range. — Sonoran Zone, in the Eastern Desert Tract of 

 New Mexico and Texas. 



Desci^lption. — Similar to t3"pical Aminosperniophilun leucurus^ but 

 darker and more strongly colored, with the head graver. The pelage 

 is much finer and longer. Tail bush}^ the lateral hairs with two free 

 black bands. The general size and length of tail are almost exactly 

 the same as in typical A. leucurus. Specimens from New Mexico, east 

 of the Painted Desert (the habitat of ArnDiOKperinophUus Ivucurus cin~ 

 jKdiionieii.s)^ in the collection of the American Museum of Natural His- 

 tory. New York, are intermediate between t3^pical leaorrt/.s and intcrpres. 



Rcinarl's. — All of our specimens were adults, taken during Februar}^ 

 and March, when they were in complete winter pelage. 



As our survey proceeded westward from the initial mojmment near 

 El Paso, Texas, no representative of the Ammosp, fiii<>j>lilh(s leucurus 

 group was found tmtil we had crossed all of the Ncm' Mexico section, 

 and a considerable part of the Arizona section of the Boundary, when 

 Aiiiinosper7nophlln!< liarrisii appeared on the western border of the 

 Elevated Central Tract. Ammospefrmoph'dm leucurus was not encoun- 



