416 Dr. J. E. Gray^s Synopsis of the American Squirrels 



of the metatarsus, (3) with a small patch of hair only in the 

 centre of the sole." (Mamm. N. A. 247.) 



It has been observed that in the species which have an exten- 

 sive geographical range there is a difference in the average 

 size of the species, agreeing with the latitudes which it inha- 

 bits. Thus several of the North-American Squirrels become 

 smaller as they extend southward, until, on the sea-coast of 

 Georgia, Florida, and the Gulf, they reach the minimum size. 



There are some species and some local varieties that appear 

 constant, and present very little variation in outer appearance; 

 and I have no doubt the difficulties which we experience in 

 studying the specimens in museums would immediately vanish 

 if we could study the animals in their native haunts. 



The colour of the back is very liable to vary, especially in the 

 larger species. In Sc. vulpinus it varies from pale iron-grey to 

 nearly black, and, on the other side, to fulvous brown grey. 

 Sc. carolinensis varies from pale iron-grey to fulvous; and a 

 melanic variety of a nearly uniform black colour is common. 



The colour of the underside is quite as variable in some spe- 

 cies. Sc. vulpinus and Sc. carolinensis, which have the under- 

 side normally of a pure white colour, sometimes have it deep 

 black, and at others reddish or reddish white. Several species, 

 especially of the smaller kind, which have the underside of a 

 reddish colour, have it sometimes much paler, and at others 

 white with a yellow tinge, or nearly white. 



Many species have a tuft of soft hair at the base of the ears : 

 this is usually white or yellow, accox'ding to the species ; but I 

 have seen it white on one side and yellow on the other in the 

 same specimen. 



The colour of the tail is generally characteristic of the spe- 

 cies ; but in some kinds it is variable, though the variations are 

 confined within certain limits in each species. The size of the 

 dark band on the hairs of the tail and the general colour of the 

 hairs constitute a pretty permanent specific character ; but it 

 sometimes varies : the base-colour changes from grey to deep 

 yellow or white ; and the black band is sometimes diffused so as 

 to make the tail almost, and sometimes entirely black, or black 

 with a minute pale tip. 



It is almost impossible to give a definite character for the 

 species in a few words; each individual requires to be described. 



2. SciURUS. 



Gray, Ann. & Mag. Nat. Hist. 1867, xx. pp. 271, 272, 325. 



Ears tufted. Head broad ; muzzle short. Feet hairy at the 

 heels. Front upper molar small or often wanting. 



