Hailey — N'orth American Species of Sigmodon. lOV 



Jalisco: Huejuquilla 1, Lagos 2, Atemajac 1, Ameca 1, Chacala 1, 

 Zacoalco 3, Zapotlan 2. 



Remarks. — S. h. berlandieri is a pale desert form of the Inspidus group 

 ranging over a wide extent of extremely arid country in western Texas 

 and northeastern Mexico and intergrading with forms to the east, south 

 and west. 



Prof. Baird described it from specimens "collected between San An- 

 tonio and El Paso by Mr. Clark and in Northern Mexico by Lieut. 

 Couch". The skulls of these two specimens still in the U. S. National 

 Museum show no important subspecif\c characters bu.t are of importance 

 geographically. The one from between San Antonio and El Paso ap- 

 parently, but not positively, (see old museum catalogue) came from 

 Presidio del Norte, and the other. No. 566, from Rio Nazas, southern 

 Coahuila (Baird, Mamm. N. A. p. 505). No type was designated but as 

 Baird gave full measurements of No. 566 this specimen is generally con- 

 sidered the type. Specimens in the Biological Survey collection from 

 Jimulco (about 30 miles south of the short Coahuila section of the Rio 

 Nazas), from near the movith of the Pecos and from El Paso, Texas, are 

 indistinguishable and are all clearly referable to this pale gray form. 

 Typical specimens of berlandieri are no nearer to typical texianus than 

 that species is to Mspidus, so that if texianus is to be recognized, berlan- 

 dieri must also be. 



Sigmodon hispidus eremicus Mearns. 



Sigmodon hispidus eremicus Mearns, Proc. U. S. Nat. Mus. XX, 504, 

 advance sheets, March 15, 1897. 



Type locality. — Cienega Well, Sonora, Mexico, on east bank of Colora- 

 do River, 30 miles south of United States and Mexican boundary line. 



General characters. — Size slightly larger than hispidus; pelage fine and 

 rather lax and soft, colors pale. 



Color. — Upperparts pale yellowish gray; belly whitish; feet light gray; 

 tail brown above, gray below. From berlandieri it differs in slightly 

 more huffy upperparts and less of the mixture of black hairs. 



Skull. — Heavy, rough and much ridged, even in specimens that are 

 not very old; coronoid process of jaw short and wide; bullae short and 

 rounded as in berlandieri. 



Measurements. — Type: total length 280; tail 128; hind foot 34. Skull 

 of type: basal length 30.6; nasals 13.3; zygomatic breadth 20.3; mastoid 

 breadth 14; alveolar length of upper molar series 6.6. 



Distribution. — Along both sides of the lower Colorado River. 



Specimens examined. — Total number 49 from the following localities: 



Sonora: Cienega Well, south of Mexican boundary on east side of Col- 

 orado River 19, Colorado River at mouth of Hardee River 11. 



California: Ft. Yuma 19. 



