34 Bulletin American Museum of Natural History. [Vol. XX-, 



brown color of the whole dorsal area, with the tips of the hairs 

 dark reddish brown instead of blackish, small ears, very large 

 audit al bullae, and the narrowness of the skull, as shown by 

 the interorbital measurement. In coloration L. aztecus is 

 not so dark brown on the middle dorsal region, and the cheeks 

 and sides of the body are gray instead of like the back, and 

 the under surface is broadly white instead of narrowly yellow- 

 ish white; the pelage is also much finer and softer. The 

 skulls are distinguishable at a glance by the large size of the 

 bullae in L. russatus, the much narrower basioccipital, and by 

 other less obvious differences. Although represented by a 

 single specimen (fortunately in excellent pelage), the differ- 

 ences which distinguish it from the nearest known allied 

 species are too strongly marked to be easily overlooked. 



I take this opportunity also to record a previously unde- 

 scribed very small Sylvilagus from the arid tablelands of 

 southern Hidalgo, collected at Apam, by Mr. Frank M. Chap- 

 man in March, 1897. 



Lepus (Sylvilagus) parvulus, sp. nov. 

 FIGURES 3, 6, AND 9. 



Type, No. |ff|f , Apam (altitude about 8000 feet), southern Hidalgo, 

 Mexico, March 19, 1897; Frank M. Chapman. 



General color above pale buff, strongly varied with black, the hairs 

 being subapically buff, with conspicuously long black tips, the pre- 

 vailing color over the posterior half of the dorsal surface being black- 

 ish, indistinctly lighter and slightly grayish on the rump; chin, throat, 

 and middle ventral surface yellowish white, the color of the sides ex- 

 tending well down upon the sides of the abdomen; prepectoral area 

 very broad, pale rusty brown; nape patch pale f errugineous ; upper 

 surface of fore feet pale rusty, of the hind feet still lighter or deep buff ; 

 eyering deep buff; sides of head buffy brown, varied with black- tipped 

 hairs;* ears externally buffy gray brown, darker, almost black on the 

 outer edge and at the tip ; ears internally pale yellowish brown with a 

 deep buffy edging; upper surface of tail blackish, the extreme tips of 

 the hairs buffy gray. 



Total length, 390; tail vertebras, ; hind foot, 75; ear, 65. Skull, 

 occipito-nasal length, 65; basal length, 54.5; greatest zygomatic 

 breadth, 33; interorbital breadth, 18.4; mastoid breadth, 27; width 



