1172 



MR. R. I. POCOCK OS THE EXTERNAL CHARACTERS 



Forsyth Major and Miller withheld that rank from them. On 

 the other hand, the Flying Squirrels, which were usually dis- 

 tinguished as the subfamily Fteromyinoi [Petauristince), were 

 granted by Miller the full family rank as Petauristid^e, equiva- 

 lent to the rest of the Squirrels or Sciuridae. A fourth sub- 

 family — Nannosciurince — admitted as valid by some authors, was 

 shown by Thomas in 1915* to be composed of heterogeneous 

 elements, the evidence of affinity between the genera derived 

 from skulls being entirely untrustworthy. 



The question of the generic classification of the Sciuridee need 

 not be discussed at length. All that it is necessary to say is 

 that in 1915 Thomas clearly showed, by his study of the os penis 



Text-fisure ViQ. 





A. Muzzle of Sciurus vulgaris, with i-liinariura exposed and partiallj'' 



concealed by hood. 



B. The same of S. saliuensis, with rhinai-ium exposed and entirelj' hooded. 



C. Ditto of Geosciurus cafensis. 



or haculwm, that previous attempts to affiliate the genera and 

 subgenei'a by their skulls and teeth and other characters had 

 in many instances yielded erroneous results, such as association 

 of GoMosciuri(,s with Sciurus and of NannosciunLS with Myo- 

 soiurus. No living student of the family would claim that we 

 know the relationship of all the groups of genera to each other. 

 The vagueness and diversity of opinions on this point, coupled 

 with the hope of finding unrecorded features of systematic value, 

 induced me to take up the study of the external charactei-s 

 presented by the ears, feet, and other organs which had been for 



* Ann. & Mag. Nat. Hist. (8) xv. p. 386. 



