SCIURUS. 95 
B. Size large, total length over 450 mm. 
a. Premolars —. 
a.’ Belly buffy or yellowish. 
a.’ Back gray. PAGE 
a./’’ Median area on back black; belly 
usually ‘deep. Gull 22 2)7 okt eee. S. oculatus 107 
b.’’’ Median area on back washed with 
blackish; belly buffy whitish........... S.toluc@ 107 
b.”” Back yellowish gray. 
a.’”’ Belly rusty yellow; total length over 
Pe AMT es = SS ia aa See eee wy aPaene” TO 
b.’’’ Belly more dingy yellow; total 
fenpea snder FOO MM... eis ieee. a! S. r. texensis 110 
b.’ Belly white. 
a.’’ Back golden buffy or yellowish, overlaid 
with grizzling of black and white..... S. nayaritensis 108 
b.” Back gray. 
a.””” Back uniform gray or grayish brown; 
ears gray; total length under soomm..... S.allent 108 
b.’’”” Back gray washed with yellowish on 
nape and back of shoulders; ears 
rusty. 
a. Total length under 500 mm.......S. arizonensis 109 
b.* Total length over 500 mm........ S.a.huachuca 109 
b. Premolars —. 
a.’ Nape patch strongly marked, rump patch 
present or absent. 
a.” Belly gray, rump patch well marked; 
DAC Garer OTe: o wjiemeik a yank vie Pires S.a.frumentor 117 
b.” Belly white or buffy. 
a.’’”” Rump patch poorly defined or absent. 
a.‘ Back dull whitish; belly white or buffy.S. soctalis 123 
b.* Back pale gray; belly white or buffy .......... 
fe Se Pad Ce eee ee ee S. p. hernandezt 118 
b.’’’ Rump patch well defined. 
a.‘ Middle of back gray; feet gray or 
plackisn: "belly: whites. o:5ccn + S. p.colimensis 119 
b.* Middle of back whitish; feet whitish; 
ete -wihthe ‘On Wulby 0 <ic-2fe dst kt iS? Sc G0c0s, ra 
ce.’ Belly rufous. 
a.’’’ Feet gray or blackish. 
-a.* Ribs, and sometimes shoulders, rufous. 
a.” Back pale gray; top of head iron 
(SE Se ae S. aureigaster 115 
