62 



NOETH AMERICAN FAUNA. 



[No. 36. 



the north. The low country on the Isthmus of Tehuantepec appar- 

 ently is an effective barrier separating the ranges of these two moun- 

 tain-loving species. 



The species exhibits considerable individual and seasonal variation 

 in color. Specimens in worn pelage very much resemble similar speci- 

 mens of rufescenSj but the ears and tail are paler. 



Specimens examined. — Total number, 154, from the following 

 localities: 



Guatemala: Calel, 23; Hacienda Chancol, 29; Jacaltenango, 1; Todoa Santos, 



10; Volcan Santa Maria, 4; Zunil, 3. 

 Chiapas: Canjob, 2; Comitan, 27; Pinabete, 8; San Cristobal, 5; Tenejapa, 3; 



Teopisca, 6; Tumbala, 33. 



REITHRODONTOMYS AUSTRALIS AUSTRALIS Allen. 

 Irazu Harvest Mouse. 

 (PI. II, fig. 3; PI. V, fig. 3.) 



Reithrodontomys australis Allen, Bull. Am. Mus. Nat. Hist., VII, 1895, p. 328. 

 Eeithrodontomys australis vulcanius Bangs, Bull. Mus. Comp. Zool., XXXIX, 1902, 

 p. 38 (Volcan de Chiriqui, Panama). 



Type locality, — Volcan de Irazu, Costa Rica. 



Distribution. — ^IMountains of Costa Rica and western Panama. 



Characters. — Similar to R. dorsalis, but shghtly smaller, with 

 smaller ears; tail less sharply bicolor; ochraceous colors slightly 

 deeper and black dorsal band less clearly defined. 



Color. — ^Upperparts ochraceous-buff, varying to pale orange- 

 cinnamon, rather heavily mixed on back with black; median dorsal 

 band usually very indistinct; underparts washed with light pinkish 

 cinnamon; ears pale fuscous to fuscous-black; tail fuscous above, 

 grayish white beneath; feet buffy white, shaded with hair-brown; 

 wrists and ankles hair-brown. 



SliuU. — Slightly smaller than that of dorsalis, with flatter brain- 

 case; bullse rather flat, averaging smaller than in dorsalis; ascend- 

 ing arms of premaxillse projecting a little beyond end of nasals; 

 upper molars simple, without accessory tubercles. 



Measurements. — Type: Total length, 169 (160-179); tail verte- 

 bra, 84.5 (82-92;) ; hind foot, 18.5 (18-19). Skull: (See table, p. 81). 



Remarlcs. — This species belongs in the rufescens group, being 

 apparently the most southerly ranging member of the group and of 

 the subgenus. It closely resembles dorsalis both in color and cranial 

 characters, and additional material from Central America may make 

 it necessary to unite the two as a single species. 



The type of vulcanius'^ from Panarna has been examined and 

 found to agree closely with topotypes of australis in the Biological 

 Survey Collection. 



