MAMMALS OK TIIK MKXIOAN BOUNDARY. 



423 



bered hills, rising above the general level of the desert basins which 

 make up this 1 racl . 



Description. This is the palest subspecies of Peromyscus boylii, 

 and differs from the more western forms in having the soles of the 

 hind feet naked to the heel. The upper surface is drab-gray, tinged 

 on sides and rump with ochraceous hull'. Bars nearly naked, with a 

 scant hoary pubescence. Tail dusky drab above, pure white below, 

 penicillate, and rather hairy throughout. Feel and under parts pure 

 white. The coloration is almost identical with that of Peromyscus 

 eremicus arenarius. Length, 202 mm.; tail vertebrae, 115; ear from 

 crown, 14; ear from notch, IS; length of head (nose to occiput), 31; 

 length of hind fool and claw, 22. Skull, 28 by 1 1. 



Cranial an<! dental characters. -The skull (fig. ( .)1) is elongated, with 

 the lengthened and depressed rostrum of typical 

 P. boylii and P. boylii pinalis-, but differs from 

 them in having the nasal hones truncate poste- 

 riorly and ending considerably in front of the 

 posterior extremities of the nasal branches of the 

 premaxillaries instead of terminating in a point 

 well behind them. The dentition (fig. 92) is very 

 different from thai of the /\ eremicus group, and 

 agrees withthe members of the /'. /< ucopus group 

 in having a subsidiary loop or fold of enamel 

 between the two principal loops at the outer side 

 of the first and second upper molars. 



Remarks. — The type was taken in a thicket 

 at the base of a cliff beside the Rio Grande. I saw a similar mouse 

 in Cataract Creek Canyon, Arizona. 



PEROMYSCUS BOYLII ATTWATERI (Allen). 

 ATTWATER BRUSH MOUSE. 



Peromyscus attwateri Allen, Bull. Am. Mas. Nat. Hist., VII, Art. X, Nov. 8, L895, pp. 

 330,331 (original description); VIII, Art. V,Apr. 22, L896, p. 65 (Lacey's Ranch, 

 Kerr County, Texas). — Mtller and Rehn, Proc. Bost. Soc. Nat. Hist., XXX, 

 No. 1, I)c.'. 27. 1901, p. 68 (Syst. Results Study N. Am. Mam. to close of HXX)).— 

 Elliot, Field Col. Mas., Zool. Ser., II, 1901, p. 135 (Synop. Mam. N.Am.); IV, 

 1904, p, 192 (.Mam. Mid. Am.). 



Type-locality. — Turtle Creek, Kerr County, Texas. (Type, skin and 

 skull, in the American Museum n\' Natural History.) 



Geographical range. — Elevated portions of Middle Texas, in the So- 

 noran /.one. Hills of Kerr and Kinney counties. 



This dark-colored form of Peromyscus boylii was described by Dr. 

 J. A. Allen from a series of specimens from round about San Antonio, 



Fig. 92.— Peromyscus 

 boylii penicillatus. 

 Crowns of molak teeth 

 oftype. a, lower series; 



h, I PPEB SERIES. 



