70 NELSON 



rusty rufous, while the two others are washed with rufous except a 

 grizzled gray band about 4 inches broad across the belly. The median 

 area on the lower surface of tail is sometimes broad, sometimes merely a 

 narrow line (the black border increasing in width as the other de- 

 creases) and varies from rusty ferruginous to yellowish brown. 



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

 length 506.2 ; tail vertebrae 256; hind foot 68.2 



Cranial characters. — Premolai's \. Skull a little shorter than that 

 of griseojlavus but scarcely distinguishable from the latter or from 

 that of S. aurcogaster. Five adult skulls from the type locality aver- 

 age : basal length 50.9 ; palatal length, 26.6 ; interorbital breadth 

 19. 1 ; zygomatic breadth 34.3; length of upper molar series 11.4. 



General notes. — The squirrels taken in the oak forest between 9000 

 and 10,000 feet altitude on the mountains at Todos Santos, Guatemala, 

 are intermediate between chiapensis and true griseojlavus^ Those 

 taken at Calel, Guatemala, are more yellowish brown and much closer to 

 griseojlavus. A specimen from the arid subtropical canyon at Nenton, 

 Guatemala (below 3000 feet) , and two others from similar localities near 

 Tuxtla, Chiapas, seem to indicate a direct gradation, in this intermediate 

 region, between S. griseojlavus chiapensis and 6". socialis. Unfortu- 

 nately our series from intermediate points is too limited to satisfactorily 

 decide this point. Surprising as it may appear, the differences be- 

 tween griseojlavus chiapensis and socialis are not greater than those 

 between the latter and S. socialis cocos. 



Habits. — The Chiapas squirrel feeds upon both acorns and pine 

 seeds, moving from one part of the forest to another with the season. 



Specimens examined. — Twelve : all from the type locality. 



SCIURUS YUCATANENSIS Allen. Yucatan Squirrel. 



Sciurus carolinensis var. yiicataitensis Allen, Mon. N. Am. Rodentia, pp. 



705-706, Aug., 1877 ; Bull. U. S. Gaol. Survey Terr., iv, p. 879, 1878. 

 Sciiirzis caro/inensis Alston, Proc. Zool. Soc. London, 1878, pp. 658-659 ; 



Biol. Cent. -Am., Mamm., pp. 124-125, June, 1880 (part: specimens 



from Yucatan). 

 Scuims vucatanensis Allen, Bull. Am. Mus. Nat. Hist., N. Y., ix, pp. 5-7, 



1897. 



Type locality. — Merida, Yucatan, Mexico. Cotypes nos. 8502- 

 8503. U. S. National Museum. 



Distribution. — Arid tropical forests of peninsula of Yucatan. 



Characters. — Back dingy, coarsely grizzled gray; belly white; 

 pelage coarse and harsh but not bristly; thin ear tufts sometimes pre- 

 sent, yellowish white; tail rather full. 



