98 SCIURUS. 



a." Top of head paler than back. 



a. 7 All of back blackish brown; PAGE 



feet, legs, lower flanks, and 



belly dull chestnut rufous S. adolphei 126 



b. 7 Middle of back blackish or 

 dark yellowish brown or gray- 

 ish yellow ; rest of body rufous . 5. a.dorsalis 127 

 b." Top of head not paler than back. 

 a. 7 Back heavily washed with black. 



a. 8 Belly rusty rufous 5. b. belli 128 



b. 8 Belly rich dark ferrugineous . 5. thomasi 126 

 b. 7 Back not washed with black. 

 a. 8 Back pale gray or sooty 



blackish. 

 a. 9 Back pale gray. 



a. 10 Feet dark gray or 

 blackish ; rufous of 

 belly sometimes ex- 

 tending up on ribs . . .5. aureigaster 115 

 b. 10 Feet pale gray ; rufous 

 of belly not extending 



on ribs S. g. chiapensis 125 



b. 9 Back sooty blackish with 

 thin wash of yellowish 

 gray. 



a. 10 Back uniform S. nelsoni 1 20 



b. 10 Back with area of 

 bluish gray across the 



middle 5. n. hirtus 121 



b. 8 Back not pale gray or sooty 



blackish. 



a. 9 Back yellowish brown, 

 sometimes thinly washed 



with gray 5. griseiftavus 1 24 



b." Back blackish, grizzled 

 with gray or yellowish; 

 under parts and costal 

 area rufous 5. a. hypopyrrhus 116 



A. Microsciurus, Allen. 



"Size small; ear short, rounded; tail shorter than body, slender, 

 rounded. Premolars, ^7. Skull short, broad, and deep at base; 

 nasals narrow and shorter than interorbital breadth, upper end of 



