434 Dr. J. E. Gray's Synopsis of the Burroiviny Squirrels 



III. Fur rather harsh, abundant ; sides with a narrow reddish 



streak. 



33. Macroxus dimidiatus. 

 Sciurus dimidiatus,Watevhouse, P. Z. S. 1840, p. 21 ; S. Baird, M. N. A. 283. 

 Fur rather harsh, abundant, reddish iron-grey; hairs short,close, 

 black at the base, with a broad pale-brown ring, a dark-brown sub- 

 terminal ring, and a white tip; upper part of head, shoulders, legs, 

 thighs, and feet, and a streak along each side of the body rufous; 

 sides of the head, chin, and beneath yellow : tail reddish, black- 

 varied; hairs reddish brown, with a broad black subterminal 

 ring and reddish end, and grey base. 



Hab. South America ? (Waterhouse's type, not in a good 

 state.) B.M. 



This specimen was purchased at a sale with some South- 

 American squirrels ; but it has much more the appeai-ance of 

 an African squirrel. No other specimen of this squirrel has 

 occurred to me ; so the true habitat is still doubtful. 



LI. — Synopsis of the Species of Burrowing Squirrels (Tamias) in 

 the British Museum. By Dr. J. E. Gray, F.R.S., V.P.Z.S. 



The Ground-Squirrels form a very natural group, and are 

 marked very similarly externally, so much so that it is very 

 difficult to distinguish them from each other. But when you 

 have a series of specimens from the same country, and from 

 different localities, you can have no doubt that they are very 

 distinct species, though it is very difficult to record the differ- 

 ence in words ; for no sooner do you think that you have hit 

 upon a distinctive character that can be written down than you 

 find it in some of the other specimens. 



The different species vary somewhat in size ; but then the 

 specimens from the same country vary a little in this respect ; 

 yet there is an average size that is characteristic of the species. 

 T. striatus of Europe and North Asia is the largest ; and then 

 follow T. Townsendii, T. americanus, then T. Hindsii and T. 

 quadrimaculatus ; and T. quadrivittatus is the smallest. 



A. Tail as long as the body ; back with five longitudinal equidis- 

 tant black streaks, separated by four pale streaks ; face with 

 a white streak extended behind, above, and under the eye. 



a. The pale streaks wide, wider in the middle. Larger. 

 Tamias striatus, Linn. 



Pale ash-grey, yellowish grey in the middle, grey on the sides. 

 Hab. Europe : B.M. Asia, Altai : B.M. 



