ON THE CLASSIFICATION OF THE SCIURIDiE. 209 



17. The Classification o£ the Sciurida.*. 

 By R. I. PococK, F.U.S. 



[Received February 5, 1923 : Read March 20, 1923.J 



(Text-figures 18-29.) 



Contents. 



Pag-e 



Introduction 209 



Description of the Penis and Baculum 212 



1. The Paltearctic aud American Species 212 



2. The Oriental Species 215 



3. The Ethiopian Species 226 



4. The African Ground-Squirrels 230 



5. The Sousliks and Marmots 233 



6. The Subfamilies of Sciuridse 236 



7. The Flying- Squirrels 240 



Introduction. 



In the following brief review * of the more important attempts 

 to classify the Sciuridse, it is unnecessary to do more than quote 

 Gray's papers, published in 1867 (Ann. Mag. Nat. Hist. (3) xx. 

 pp. 270-286, 323-334, 415-436). The results he achieved were 

 of no great moment from my present point of view, but he 

 introduced a number of new sectional names which have to be 

 borne in mind. In 1880, Trouessart (Le ISTaturaliste, i. pp. 290- 

 293, 315) made a similar but moi-e successful and useful efibrt, 

 proposing several new names but ignoring those of Gray as 

 connoting groups composed of unrelated elements. He divided 

 Sciurus into seventeen subgenera, amongst which appear such 

 well-defined forms as Rheithrosciurus and JTerMS, which he regarded 

 as equivalent to N^eoscmrus, Parasciurus, Echinoschirus, and 

 Tamiasciurus, dismembered from Sciurus on certain comparatively 

 trivial characters presented by some of the American species. 



The most important contribution to the subject was made in 

 1893 by Forsyth Major (Proc. Zool. Soc. 1893, pp. 186-190) from 

 a study of the teeth and skulls. He recognised the three sub- 

 families Sciui'inae, Pteromyinfe, and Nannosciurinse. The Sciurinse 



* I have not here taken into account the numerous papers on American Sciuridaj 

 which belong to four well-marked and universally admitted types — namely Sciurus, 

 Tamias, Citellus, Cynomys, and Marmota. As compared with the true arboreal 

 Squirrels of the Old World, the American species oi Sciurus are singularly uniform 

 in essential chai-acters, although a large number of subgenera are admitted. Citellus 

 has been similarly broken up into subgenera, and Eutamias has been dismembered 

 from Tamias. 



