256 MAMMALS. 



it up into brigades. After separating from them the jMarraots, Ground Squirrels, and Flying 

 Squirrels, we have a very homogeneous section, the Squirrels proper, which peculiarly require 

 further subdivision, but for which it is scarcely possible to find good sectional characters. One 

 small section may, indeed, without inconvenience be subtracted from it, viz. : — 



Bristly Squirrels. (Xeri.) (Map. 92.) These are Squirrels with bristles or spines in their fur; 

 they are confined to Africa, south of the Sahara. The Map shows their range, but only those 

 places where the genus has been actually taken, and these, it will be seen, extend along the coast 

 almost all round the continent, — Senegal, Fernando Po, Congo, South Africa, Somali-land, 

 Abyssinia, and Senaar. We may, therefore, expect that it will be found all over it, but until it has 

 been ascertained to be so, I have refrained from assuming it. 



SciURUS. (Map 93.) The remaining Squirrels, even thus restricted, are still a numerous genus. 

 There are about one hundred and eighty species, standing described in systematic works, of which, 

 however, at least the half are synonymes ; and I have little doubt that if the remainder were 

 subjected to the same stringent scrutiny' that Audubon and Bachman's North American species* 

 have undergone at the hands of Dr. Baird, and with the same advantages of materials collected by 

 Government exjDlorations, they would be correspondingly reduced. 



The great accumulation of synonymes and doubtfid species is due to the variability of most 

 of the species both in size and colour. Speaking of the Indian species, Sc. jlwimus, Mr. Blyth, who 

 perhaps has had more experience of Indian species than any other naturalist, says, " It exhibits 

 permanent varieties of colouring, each peculiar to a certain range of distribution ; and in some 

 instances the size is more or less reduced, e.g., Sc. hypoleucos and Sc. albipes. It is difiicult to 

 conceive of the whole series as other than permanent varieties of one species ; and the same 

 remark applies to the races of Pteromys, and to at least some of those of Sciuropterus, as also to 

 various named SciURi."t And not to speak of varieties and local races, from time to time indicated 

 by Mr. Blyth, he says of the whole of the group of medium-sized Squirrels with grizzled fur, proper 

 to south-east Asia and its Archipelago : " Extraordinarily developed in the Indo-Chinese countries, 

 and Malayan Peninsula, where the species or permanent races would seem to be almost endless, 

 differing more or less in size and colouring.''^ Dr. Baird makes similar remarks upon the North 

 American species : " The determination of the species of Squirrels of North America has always 

 been a matter of o-reat difiiculty. Owing to many different reasons, the species themselves exhibit an 

 unusual tendency to run into varieties of colours, among which red, grey and black, are the pre- 

 dominating ones with all possible intermediate shades ; these varieties are sometimes more or less 

 constant in particular localities, sometimes changing with every litter. I am not aware that there 

 is any material diiference of colour at different seasons or ages in the same animal."§ Mr. Blyth 

 found the Indian varieties also constant to their localities: "The next four races," says he, "with 

 probably others, are also very closely akin, but inhabit different localities, from which they are 

 respectively true to the details of their colouring."|| Another source of perplexity, noticed by Dr. 

 Baird, is the alteration in the average size with the latitude. " Many of our animals," he says, 

 " become smaller as we proceed southwards, until on the sea-coast of Georgia, Florida, and the Gulf, 



* Sir Charles LycU tells us of the remonstrauce of — Lyell's " Second Visit to the United States," vol. i. 



a subscriber to Audubon and Bachman's Quadrupeds p. 302. 1850. 



of North America on this subject : " If you describe t Blyth, Cat., p. 98. J iBm. p. 101. 



.so many squirrels I cannot go on taking in your book." § Baikd, op. cit. || iBm. p. 101. 



