92 SYNTHETOSCIURUS. 
Fig. 12. SYNTHETOSCIURUS BROCHUS. 
No, 10402 Mus. Comp. Zool. Coll. Nat. Size. 
Color. Above mixed olivaceous bistre and dull tawny olive; 
under fur dark mouse gray; under parts orange rufous; tail above like 
back, less olivaceous beneath, fringed with pale rusty. 
Measurements. Total length, 320; tail vertebrae, 150; hind foot, 
46; ear, 17. Skull: basal length, 35.6; occipito-nasal length, 44; 
zygomatic width, 25.2; interorbital width, 12.6; palatal length, 20; 
to end of pterygoid, 27.4; length of nasals, 13; width of nasals, 5.8; 
length of upper molar series, 7.6; length of mandible, 27. 
The next genus Scrurus, with its subgenera, contains the tree 
squirrels whose lives are passed among the branches. It possesses 
the largest members of these animals in North America, and they are 
all remarkable for the long bushy tail, often exceeding the head and 
body in length, and which when elevated over the back, is both a 
beautiful ornament and a protecting shade. The genus is a very 
large one, and has representatives in many parts of the globe, and 
the species differ greatly in size and especially in coloration, in which 
there is almost endless variation; and as if it were not sufficient for 
distinct species to differ from each other, it was evidently deemed 
necessary that individuals of the same species should sometimes be 
totally unlike in the hues of their coats. It is this variation in color 
