MAMMALS OF THE MKXK AN BOUNDARY. 457 



From fcopotypes of Baird's Reithrodontomys longicauda, his /.'. pallidus 

 t lnis becoming a complete synonym of A', longicauda, it is equally plain 

 thai Allen's pallidus is thoroughly composite, his table of 157 speci- 

 mens embracing series of true longicauda and typical deserti, which I 

 myself examined and measured in the field, from several localities on 

 the Colorado Desert and the Pacific slope, wot of the Coasl Range, 

 as well as specimens from the San Bernardino Valley and othei locali- 

 ties, which perhaps represented intergrades between the form of the 

 interior desert region (R. m. deserti) and that of the Pacific Coasl -trip 

 ( /,'. longicauda). I regard»i1 as probable that the four forms of the 

 R. megalotis group, named above, will eventually he proved to he 

 conspecific, in which ease the latter three (arizonensis, deserti, and 

 longicauda) will have to stand as subspecies of Reithrodontomys mega- 

 lotis (Baird), which was the first one named. 



The several forms of this genus known from t he region of the Bound- 

 ary may, perhaps, be identified by reference to the following 



KEY TO REITHRODONTOMYS FOUND OX THE MEXICAN BOl NDARY. 



a. Total length more than 150 mm. 



b. Total length less than 170 mm. Above yellowish brown mixed with black, but with- 

 out a darker vertebral area; sides faintly fulvous. .Reithrodontomys laceyi (p. 158 

 bb. Total length more than 170 mm. 



c. Length, 178 mm.; tail vertebrae, !•'■•: ear. 12. Above grayish brown with a yellow- 

 ish wash; sides strong yellowish fulvous; below dull whitish. 



Reithrodontomys mexicanus intermedins 1 p. 457). 

 cc. Length, 172 mm; tail vertebrae, 99; ear, 14. Above pale yellowish brown, lined 

 with black, with a blackish median area; sides light yellowish: below white. 



Reithrodontomys fulvescens (p. 159 . 

 an. Total length less than 150 mm. 



(I. Coloration pale, above yellowish gray, lined with darker, and mure fulvous on 

 sides. 

 «. Tail one-half the total length; color above yellowish gray, considerably mixed 

 with blackish; pelage full and soft. .... .Reithrodontomys megalotis (p. 160). 



a. Tail more than half the total length; color above yellowish, hut little mixed 

 with darker: pelage short and somewhal harsh. 



Reithrodontomys megalotis deserti (p. 162 . 

 </</. Coloration dark: above yellowish brown, lined with blackish, with a darker 

 median dorsal area. 

 f. Length, lis mm.: tail vertebrae, 77: hind foot. 17. Top of bead grayish 



brown Rt ithrodontomys longicauda I p. Hit . 



ff. Length, 149; tail vertebrae, 78; hind foot , 17. Top of head reddish brown. 



Reithrodontomys arizonensis (p. 159 . 



REITHRODONTOMYS MEXICANUS INTERMEDIUS Allen. 



TAMAULIPAS HARVEST-MOUSE. 



Reithrodontomys mexicanus intermedins Allen , Bull.Am.Mus. Nat. Hist.,VII,p. 136, 

 May 21, 1895 (original description): VIII, 1896, p. 236 (in text). Mn.i.ia: and 

 Ki'.iin. 1'roe. Bost. Soe. \:,t lli~ i . XXX, No. I. Dec. 27, 1901, p. 99 Sysl 

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



