106 SCIURUS. 
D, Arosciurus. 
Premolars, —, Skull broad, depressed between orbits; superior 
outline curved greatly at occipital region; orbital region very broad; 
postorbital process curving downward, and pointed; nasals long, 
extending posteriorly to end of premaxille. 
Fic. 16. SciuRUS (ARAZOSCIURUS) NAYARITENSIS. 
No. 4741 Field Columbian Mus. Coll. Nat. size. 
KEY TO THE SPECIES AND SUBSPECIES OF THE SUBGENGS 
\: I I 
A. Size large. Premolars, ==>, PAGE 
a. Back with longitudinal black band...........S. oculatus 107 
b. Back without longitudinal black band. 
a.’ Under parts white. 
a.’’ Above gray, washed with blackish; tail 
beneath yellowish gray or brown .......S. 0. toluce 107 
b.” Above grizzled yellowish brown; tail 
beneath grizzled yellowish gray ............ S. allent 108 
