98 SCIURUS. 
a.” Top of head paler than back. 
a.’ All of back blackish brown; 
feet, legs, lower flanks, and 
belly dull chestnut rufous..... S. adolphet 
b.’ Middle of back blackish or 
dark yellowish brown or gray- 
ish yellow; rest of body rufous. S.a.dorsalis 
b.° Top of head not paler than back. 
a.’ Back heavily washed with black. 
a. Belly rusty. nulous =5.) see S. b. belti 
b.° Belly rich dark ferrugineous.S. thomast 
b.' Back not washed with black. 
a. Back pale gray or sooty 
blackish. 
a.” Back pale gray. 
a.” Feet dark gray or 
blackish; rufous of 
belly sometimes ex- 
tending up on ribs. ..S. aureigaster 
b.” Feet pale gray; rufous 
of belly not extending 
ONVEISS {oth eee S. g. chiapensis 
b.” Back sooty blackish with 
thin wash of vellowish 
gray. 
a.) back tinihonnn pre S. nelson 
bs.) Back” wath! jareas sor 
bluish gray across the 
micelle), Arian tne peencmente S.n. hirtus 
b.* Back not pale gray or sooty 
blackish. 
a.’ Back yellowish brown, 
sometimes thinly washed 
with gray ..........%.S. graseqfiaums 
b.” Back blackish, grizzled 
with gray or yellowish; 
under parts and costal 
area rufous. 225. S. a. hypopyrrhus 
A. Microsciurus, Allen. 
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“Size small; ear short, rounded; tail shorter than body, slender, 
2 
rounded. Premolars, =. Skull short, broad, and deep at base; 
nasals narrow and shorter than interorbital breadth, upper end of 
