SQUIRRELS OF MEXICO AND CENTRAL AMERICA 49 



back ; tail above black, heavily washed with white ; below, with 

 broad median band varying from dingy grizzled yellowish gray to 

 pale rusty, a poorly defined black border and broader edging (and 

 sometimes wash over entire lower surface) white ; chin and throat 

 white; rest of underparts usually white, sometimes varying to pale 

 buffy or rusty buff. Hairs on back black with white tips and yellow- 

 ish basal rings, mixed with others having subterminal and basal rings 

 of dull yellowish, and still others with black subterminal, and yellow- 

 ish median rings. 



Variation. — The yellowish ringed hairs on the back vary somewhat 

 in number but are not sufficiently numerous to appreciably effect the 

 general color. A faint yellowish indication of the rump patch is some- 

 times present, but always indistinct. No melanistic specimens seen. 

 Specimens from the arid Lower Sonoran and upper edge of the Arid 

 Tropical zones in northwestern Oaxaca, southwestern Puebla, and ad- 

 jacent part of Guerrero are closely related to herna?idezi, but are 

 slenderer with backs whiter, nape and rump patches more distinctly 

 yellowish brown ; underparts usually buffy but sometimes white, and 

 median area on underside of tail bright rusty ferruginous. The char- 

 acters presented by these squirrels are almost worthy of subspecific 

 recognition, but the material at hand is too limited to satisfactorily de- 

 termine their value. 



Measurements. — Average of five adults from type locality : total 

 length 539.6; tail vertebrae 268.8; hind foot 68.8. 



Cranial characters. — Premolars \. Skulls average a little smaller 

 (with longer upper molar series) but are not otherwise distinguishable 

 from those of S. poliopus. Five from type locality average : basal 

 length 51.5; palatal length 26.5; interorbital breadth 19.5; zygomatic 

 breadth 34.6; length of molar series 11. 



General notes. — The name first proposed for this squirrel being 

 preoccupied, the subspecies was i"enamed in honor of Francisco Her- 

 nandez, the author of the Historise Animalium Novs Hispaniae. 



Habits. — These squirrels feed upon acorns and pine nuts, and at 

 the time of our visit to the type locality, in September, were found in 

 the huge oak trees growing along certain slopes and ridges in the pine 

 forest at an altitude of 8000-9000 feet. They were shy, and instead 

 of concealing themselves at our approach, usually made off through 

 the tree tops. 



Specimens examined. — Twenty-one : from mountains west of Val- 

 ley of Oaxaca, southwestern Puebla and southeastern Guerrero. 



