CLASSIFICATION OF THE SCIURID-E. 241 



elements, and pointed out that it is divisible by the structure of 

 the teeth into six genera : — Scmropterus, type riissieus, for the 

 Palfearctic species ; TrogojJterus for .vanthipes from China ; 

 BeloviT/s, type pearsoni, Pteromyscus, type jfjitfoent^e^ii^MSy 

 Fetaurillus, type hosei, and lomys, type horsjieldi^ from various 

 parts of the Oriental Region, each containing one or more 

 species besides the type. Furthermore, he divided Scmropterus 

 into four subgenera : Sciuropterus itself ; Glaucomys for the 

 North American volans and the Himalayan^m6rmi;z<.s*; Hylojjetes, 

 containing many species ranging from Nepal to the Malay 

 Islands, with everettii as the type; and Petinomys, ranging 

 from Ceylon into South India and the Malay Islands, with lugens 

 as type. 



Owing to lack of material, I can contribute very little to what 

 has been already established as to the affinities of the genei-a of 

 this family. The outstanding result of my examination of the 

 bacula is the complete severance of Eoglaucomys from Glaucomys. 

 This suggests tliat further surprises may be in store for him who 

 has the time and opportunity to carry on the work. 



The penis and baculum are as variable in the Petauristidse as 

 in the tSciuridse. The penis itself is only known to me in two 

 genera, Eoglaucomys and Ilylopetes, of which one specimen of 

 each, preserved in alcohol, has been available. 



In Eoglauoom-ys fimhriatus the glans is stout and tolerably 

 long, a little stouter just beyond the middle than at the base, 

 and slightly upcurled but not appreciably narrowed at the end. 

 On the left side above, just before the tip, there are three 

 processes in a line, the first and third short and semiconical, 

 the second or middle one much higher and roughly three-sided. 

 Beyond these the apex of the glans forms a lamina hollowed on 

 the left side, and beneath this there is a rounded area with a 

 fleshy flap defined by a groove which passes backwards on to the 

 right side, where the area in question is narrowed and runs 

 bMckwai-ds, being defined above and below by a groove. The 

 orifice appears to be situated towards the posterior end of the 

 upper groove, and from the orifice two more grooves run back- 

 wards to the proximal end of the glans. (^Text-tig. 27, A-C.) 



The baculum, measuring 7*5 mm., is exceedingly short and 

 occupies only the distal half or less of the glans. It is furnished 

 with several processes, and agrees tolerably closely in shape to 

 the shape of the end of the glans. It is indeed the bony processes 

 of the baculum, enveloped in soft tissue, which give shape to 

 the end of the glans ; but the rounded area of the glans below 

 the distal hollow is wholly composed of soft tissue, no portion of 

 the baculum entering it. The proximal end of the baculum 

 forms a short, stout rod, shorter than the terminal toothed por- 

 tion and emarginate below. Considering the former association, 



* This species was subsequentlj' separated from Glaucomys as tlie tj'pe of tlie 

 subgenus JSoglaucomys. 



