new South- American Mammals. 151 



white. Arms and legs like back ; wrists and ankles rufous ; 

 hands and feet blackish. Under surface dark brown, the 

 chest and middle line of bellj prominently grizzled with 

 whitish. Tail, as usual, broadly washed with white. 



Dimensions of the type (measured in skin) : — 



Head and body 270 millim. ; tail 310 ; hind foot (wet) 57 ; 

 ear (wet) 26. 



Hab. of type, Balzar Mountains, on the Upper Palenque 

 River, W. Ecuador. Another specimen from Chongon 

 {Simons). 



Type (male). B.M. no. 80. 5. 6. 81. Collected by 

 Mr. Ulingworth. 



The three races now recognized may be briefly distin- 

 guished as follows : — 



S. stramineus typicus. — General colour dark ; no nuchal 

 patch. Under surface dark brown. 



S. s. JSehouxii. — General colour light; a nuchal patch. 

 Under surface pale grey. 



S. s. guoyinus. — General colour pale; no nuchal patch. 

 Under surface brown, grey mesially. 



Phyllotis gerhillus, sp. n. 



A small species, not unlike a Peromyscus in general pro- 

 portions, with typical desert-coloration, such as is found in 

 many Gerbilles ; quite unlike any Neotropical species hitherto 

 described. 



Size rather larger than in Mas musculus. Fur soft, sleek 

 and shiny, the hairs about 5-6 millim. long on the back. 

 General colour of head and back clear sandy fawn, rather 

 variable in tone, but on the whole very similar to that of the 

 Egyptian Gerhillus gerhilhis. Individually the hairs are 

 slaty at their bases, then whitish, with their visible ends 

 fawn, finely tipped with blackish. Ears proportionally large, 

 pale grey. Under surface wholly pure white, the line of 

 demarcation fairly well marked, and so high that the white 

 includes the whole of the limbs, fore and hind, from the 

 shoulders and hips downwards, the fawn not extending on 

 to the limbs at all. Tail fairly well haired, faintly pencilled, 

 wholly white, or the median line above slightly darker. 



Skull practically a miniature of that of Ph. llaggardi^ but 

 the zygomata rather more widely expanded. 



Dimensions of the type (measured in the flesh by col- 

 lector) : — 



Head and body 82 millim.; tail 90; hind foot (s. u.) 20; 

 ear 17. 



Skull: greatest length 24; basilar length 18 ;* zygomatic 



