Subgenera of t/ie Sc'iavoptenii Group. 3 



Trogopterus xanthipes is a character of generic rank, while in 

 addition tliat species is to a certain extent hypsodont, which 

 is not the case in Belomys. 



With less complicated teeth than Belomgs, though still 

 much more so than in Sciuropterus, is 



Pteromyscus, gen. 



nov. 



Molars agreeing with those of Belomys in their general 

 structure, but the degree of complication is less. Thus, 

 among other details, there is no notching off of an anterior 

 portion of the inner longitudinal boundary-wall, and the spout- 

 like projection in the middle of the outer edge is less 

 developed. 



;/ a little smaller than in Belomys, barely or not equalling 

 m} in area, p^ minute, closely crushed against the antero- 

 internal side of p'*, and often hardly visible from above. It 

 is present in all the skulls available, but looks as if it could 

 hardly be of any functional value. 



Ears quite small, untufted. 



Type — Pteromrjscus pulverulentus [Sciuropterus pulveru- 

 lentus, Giinth.). 



A second species described below. 



Petaurillus, gen. nov. 



Molars with very low, rounded, and almost obsolete ridges, 

 quite different from the high and well-defined ridges present 

 in Sciurop)terus, although their relative positions are much 

 the same. The ridges not wrinkled or notched. 



/>* distinctly smaller than m^ ; not of the usual triangular 

 shape, but nearly symmetrical, its outer scarcely longer than 

 its inner border, p^ well developed, standing in front of the 

 centre of />'*, not overlapped by it. The three anterior teeth 

 of the row, therefore, evenly and symmetrically diminish in 

 size forwards, a condition not found in any of the other 

 groups. 



ISkuU in general form short, broad, and low, with a short 

 nmzzle. Bull^B well swollen, the mastoid portion also slightly 

 inflated. 



Mammre 4. 



Type — Petaurillus /losei {Sciuropterus hosci, Thos.), 



A second species described below. 



The two species of retaurillus are the pigmies of the 

 grouj), being decidedly smaller than the smallest species of 

 Sciuropterus. They are readily distinguishable by the straight 



1* 



