2 Mr. 0. Thomas on the Genera and 



a consequence the teeth appear from above to be simply 

 quadricuspidate, and when viewed from their inner aspect 

 show two definite cusps instead of the usual single crest. 



No small upper premolar ( p^) present. 



Usual antero-external cusp of />* situated more mesially on 

 the tooth, so as to function partially as a p^, 



BulltB well inflated. 



Type — lomys horsfieldii^Pteromys {Sci'uropierus) Jiorsfieldi, 

 Waterh.). 



Other species : I. thovisoni^ Thos. ; /. davisoni, Thos. 



This genus is readily distinguishable from any member of 

 tlie group by its peculiar quadricuspidate teeth and by the 

 entire suppression o^ p^. 



Figures of upper and lower molars of /. horsfieldi have 

 been given in Dr. Major's paper *. 



Belomys, gen. nov. 



Upper cheek-teeth brachyodont, but exceedingly compli- 

 cated, as in Trogo'pterus^ masking the essential pattern, which 

 is, however, as in Sciurojderus. The ridges are deeply 

 grooved, wrinkled, and excavated, and not only is the postero- 

 internal cusp of each tooth separated by a deep notch from 

 the main part of the inner longitudinal crest, but the anterior 

 end of the same crest is cut off by another deep notch from 

 the middle part. The inner aspect of m^ and m^ shows there- 

 fore three cusps — a small anterior, a middle larger, and a 

 fairly developed posterior. Externally, where in some species 

 of SciurojJterits there is a small supplementary cusp at the 

 exit of the middle valley, there is a well-marked externally 

 projecting angle, deeply grooved down its centre, so as to 

 form a projecting gutter. ^* not immensely large as in 

 TrogopteruSj but nevertheless larger than m^ ; p^ compara- 

 tively large, internal to the front cusp of p^. 



Ears large, their bases in the known species with tufts of 

 bristles. 



Type — Belomys pearsoni {Sciuropterus pearsom, Gray). 



Other species : B. viUosus^ Blyth, from Upper Assam, 

 which is probably different from the Darjiling B. pearsoni ; 

 B. kaleensis, Swinhoe, from Formosa; and the Manipur 

 species described below. 



This form was included in Trogopterus by Heude on the 

 statement by Forsyth Major that its molars were of similar 

 pattern f ; but it appears to me that the hypertrophy of p* in 



* P. Z. S. 1893, p. 194, pi. Tiii. fig. 21 and pi. ix. fig. 21. 

 t T. c. pi. viii. fig. 20 and pi. ix. fig. 20. 



