THE QUADRUPEDS OF ARIZONA. 355 
less prominent and conspicuous than that of the large 
carnivores or ruminants, it is not on that account the less 
interesting. And even in an economic point of view, it 
is scarcely less important; for the commercial value of 
the fur of some species, and the destructive agency of 
others, in field or in warehouse, gives them a consequence 
to a degree surpassed by no oiher animals. Aside from 
these practical considerations, the naturalist finds in this 
extensive group large room for study and investigation ; 
and the diversity in form and structure and variety in 
habit exhibited, cannot fail both to please and instruct. 
e transition from the graceful, vivacious, arboreal 
squirrels to the clumsy, inactive, terrestrial marmots is 
great; but no intermediate links in the chain are wanting, 
and each one is curiously wrought and chased, with a 
story of its own to tell. Space will allow me to notice in 
detail only some of the more prominent rodents; and of 
the others I must perforce “make mere mention.” 
Family Sciuride, the Squirrels, ete. The most char- 
acteristic, as well as most abundant species of Squirrel, is 
the Tuft-eared ( Sciurus Abertii), discovered by Dr. Wood- 
house in the San Francisco Mountains. It is one of the 
largest, and certainly the very handsomest of all our 
North American species. Besides very beautiful and 
harmonious colors, it rejoices in the possession of long 
pointed ear-tufts, extending an inch or more from the 
edge of the conch of the ear, which give it a peculiarly 
Sprightly and truly elegant appearance. But it is not | 
the case, as generally believed, that these ornaments are 
constantly present. Ido not know what regulates their 
_ growth or fall; but certain it is, that under some circum- 
stances, or at certain seasons, they are wanting, either 
wholly or in part. I have eyen shot specimens on the 
