230 PROCEEDINGS OF THE NATIONAL MUSEUM. 



33. PHYLLOTIS DARWINI POSTICALIS Thomas. 



Twenty-five specimens, as follows: 



Hiiaracondo, 11,000 feet, 9 (Nos. 1945G6-T0, 194713^, 194T16, 

 194777). 



Chospyoc, 10,000 feet, 7 (Nos. 194571^, 194718, 194720, 195099). 



Macliii Picchu, 12,000 feet, 4 (Nos. 194575-6, 194721, 195091). 



Ocobamba Valley, 9,100 feet, 2 (Nos. 194578-9). 



Ollantaytambo, 13,000 feet, 2 (Nos. 194577-194722). 



Puqiiiura, 1 (No. 195110). 



As usual in this group the present series shows a good deal of 

 variation both in size and color, and some of the specimens, notably 

 those from Chospyoc, tend to resemble the paler subspecies limatus, 

 which ranges from near Lima eastward to Arequipa, whence a con- 

 siderable number were sent by Simons. The type locality of posti- 

 calis is Galera, on the heights of the Andes west of Oroya, depart- 

 ment of Junin. 



Owing to the manner in which the collector has pulled out the base 

 of the tail, a tendency to buffy coloration on the hinder rump appears 

 more prominent in these specimens than in Mr. Simons's skins, but. 

 although not mentioned in the descriptions, it is present in a variable 

 degree in most examples of the group. 



34. HESPEROMYS FRIDA Thomas. 



1917. Uesperomys frida Thomas, Smiths. Misc. Coll., vol. 68, No. 4. p. 1. 

 April 10, 1917. 



A large, comparatively long-tailed species, with the supraorbital 

 ridges little divergent. Size about as in the largest species of the 

 restricted genus Hesperojm/s. Fur close and fine ; hairs of back about 

 9 mm. in length. General color of specimens in unbleached pelage 

 grayish drab, becoming more like " wood-brown " posteriorly ; in 

 bleached pelage the posterior back may be nearly cinnamon; sides 

 lighter and more bufFj^ the edge of the belly color with a more or less 

 marked buffy line. Under surface gray, the bases of the hairs slaty, 

 their tips grayish white. Ears rather large for this genus, colored 

 like head. Hands and feet pure white. Tail nearly equaling the 

 head and body in length, inconspicuously grayish brown above, white 

 on sides and below. Mammae 2-2=8. 



Skull (pi. 14, fig. 3) shaped like that of a Phyllotis or of the 

 smaller species of riesperom,yf<., the interorbital region flat, square 

 edged, but without the broadly divergent ridges found in the other 

 Hesperojnys of this size. Zygomatic plate projected forward, its 

 front edge vertical or very faintly concave; never distinctly under- 

 cut. Mesopterygoid fossa narrow. 



jNIolars absolutely brachyodont, and thus different from the semi- 

 hypsodont teeth of PhyllofAs. 



