1893.] DB. C. J. rOESTTH MAJOE Oy MIOCES-E SQUIBIIELS. 187 



systematic Zoology should not take into consideration, more than 

 has been the case hitherto, the characters of the skull and dentition 

 of Sciuromorpha, which characters have been of such excellent 

 service for Myomorpha. 



My arrangement of the >Sciurid89 (see the table, p. 1S9) contains 

 three subfamilies : — 



1. SciuriiKP, including the genera of the subfamily S'chn'iuo' of 



authors (with the exception of the Flying-Squirrels and 

 some pigmy forms), as well as the members of the sub- 

 family Arcfoini/iiur (Ci/HOi»i/-t, Arctonv/s, Spenaophilas). 



2. Pteromi/inoe, including all the Flying-Squirrels (Sduroptems, 



Pteromijs, Eupeinurux). 



3. JVcoinosciuriiuf, the Oriental Pigmy Squirrels Sc. e.rUis, S, 



Miill., Sc. melaaoiis, Miill. & Schleg., Sc. concinmis, Thos. ', 

 <SV. wldti'headi, Thos. -, as well as the Ethiopian Pigmy 

 Squirrel, Sc. nnnvfrn, Du C'haillu. 



I shall say a few words on the Pteromi/iiue when dealing \\ ith 

 the fossil forms. 



As to my subfamily Snnr'nur, the inclusion.of the Arctoini/hue in 

 the subfamily Sclurimi', which appears at first sight to be a radical 

 change, will, 1 am sure, meet with the least opposition. The close 

 relationships of Spermophllus to Tamiax and Sciurus are generally 

 recognized ; and my scheme is further justified by the consideration 

 that several Xorth- American species of the heterogeneous genus 

 SpennopJiUiis show in their skidl and dentition a striking analogy 

 with Xenis, a circumstance which has been generally overlooked. 

 Besides, the dejitition of the Arctoiiii/inre is so decidedly Sciurine 

 that I do not see why we should any longer keep Arc/oim/s and 

 Spermophihm artificially separated from Xems and Sciums, for no 

 other reason than con\enience. 



As to the minor divisions, it results from the preceding remarks 

 on the dentition of Sciurincp that tlie Ethiopian Xerm occupies, 

 with its three species, a much less isolated position than has 

 hitherto been admitted, inasmuch as numerous species of Ethiopian 

 Squirrels, as well as some Oriental forms, included in the genus 

 Sciurus, have close relations to Xerus in characters, which at the 

 same time approach it to the Hystricomorpha. The cliaracters of 

 the skull of Xerus and its congeners point in the same direction, 

 and consist, to express it briefly, in the elongate form of the 

 cranium in general and the froutals particularly, coupled with the 

 shortening of the postorbital processes ; whereas the remnant of 

 Scimince are, on the contrarj^, characteristic for their broad frontals 

 and the long postorbital processes. Moreover, a small group of 

 Ethiopian Squirrels, related to Xerus (Sc. stamjeri, Sc. ehii, Sc. 



' Ann. Mag. Nat. Hist., Nov. 1888, pp. 407, 408. Hah. Isabella, Easilan, 

 Philippines. 



- Ann. Mag. Nat. Hist. (5) 1887, xx. p. 127; P. Z. S. 1889, p. 2^31. Hr,/j. 

 Borneo. 



