52 



NORTH AMEEICAN FAUNA. 



[No. 36. 



men, an adult male, equals toltecus in size and agrees perfectly with it 

 in skull characters. Several other skulls in the series, however, 

 equally old, are very much smaller — as small, indeed, as typical 

 tenuis, while between the two extremes is a nearly perfect series of 

 intergrades. 



Two specimens from Patzcuaro, Michoacan, including the type of 

 "inexspectatus/' do not differ appreciably from toltecus. The topo- 

 type has the underparts strongly suffused with ochraceous and has 

 no white on the tail. This species differs mdely in skull characters 

 from levipeSj with which it was originally associated as a subspecies. 



Specimens examined. — Total number, 30, from the following locali- 

 ties in Mexico : 



Mexico: Tlalpam, 3. 



Hidalgo: Marques, 1 (skull); Zimapan, 1. 



San Luis Potosi: Rio Verde, 6. 



Michoacan: Los Reyes, 13; Patzcuaro, 2;^ Zamora, 4. 



REITHRODONTOMYS FULVESCENS HELVOLUS Merriam. 

 Oaxaca Harvest Mouse. 

 (PI. II, fig. 9; PL V, fig. 9.) 

 Reithrodontomys griseoflavus ^eZvoZits Merriam, Proc. Wash. Acad. Sci,, III, 1901, p. 554. 



Type locality. — Oaxaca City, Oaxaca, Mexico. 



Distribution. — Interior plateau of Oaxaca, Guerrero, and Puebla. 



Characters. — ^About the size of toltecus but differing in paler colors, 

 larger ears, and smaller skull; very similar to tenuis, but color of back 

 and sides more pinkish (less ochraceous) and belly whiter. 



Color. — Upperparts light ochraceous-salmon, sparingly lined with 

 black but without a distinct median band; underparts white, often 

 with a slight yellowish tinge, but never (in type series) with any 

 suffusion of ochraceous. Ears dark hair-brown, clothed on inner sur- 

 face with ochraceous hairs; tail fuscous or hair-brown, soiled whitish 

 below. 



Slcull. — Smaller than that of toltecus and shghtly larger than that 

 of tenuis; braincase rounded and moderately inflated, narrowed pos- 

 teriorly; rostrum rather short; interpterygoid fossa actually and 

 relatively broader than in either toltecus or tenuis. 



Measurements. — Average of 11 adults from type locahty: Total 

 length, 189 (181-200); tail vertebrae, 110 (104-116); hind foot, 20.5 

 (20-21); ear, 13.2 (12.5-13.7). Skull: (See table, p. 81). 



Bemarlcs. — This subspecies agrees in size with toltecus, but most 

 nearly approaches tenuis in color and cranial characters. No inter- 

 mediate specimens between lielvolus and tenuis have been examined, 

 however, and our present knowledge of the distribution indicates a 



1 Including type of 'Hnexspectatus" from Collection Field Mus. Nat. Hist. 



