414 JOURNAL, BOMBAY NATURAL HIST. SOCIETY, Vol. XXVI. 



The following growth table resulted from an examination of 65 

 individuals from Sikkim ; — 



The skull is large, the average condylo-basal length being about 

 41 mm. The temporal ridges traverse the brain-case at a rather 

 low level, but form strong beads on the posterior portions of the 

 frontals. The nasals are considerably longer than in JR. rattus ; 

 the diasteme and the pterygoid region are also longer, while the 

 bullae are smaller. These differences will be appreciated best from 

 the measurements in the tables II (A), part III. In the cheek- 

 teeth, TO. 1 has the antero-external tubercle ( cusp 1 ) greatly 

 reduced — almost indistinguishable from the median tubercle 

 (cusp, x.).^ 



Remarks: — The claim of 11. nitidus to rank as a species distinct 

 from B. rattus is placed bej^ond question by its characteristic 

 external appearance, peculiar skull, and its restricted distribution 

 in India, where it is confined to the Himalayas. The large number 

 of specimens now at hand from many localities in Kumaon and 

 Sikkim agree closely with each other, as well as with Hodgson's 

 type from Nepal. There is, of course, in this long series a good 

 deal of minor individual variation in colour ; but viewed broadly the 

 coloration is remarkably uniform, while the essential characters 

 relating to the quality of the pelage, mammaj, external and cranial 

 proportions appear to be very constant. The statement in Thomas's 

 paper of 1881, repeated in Blanford, to the effect that the fur 

 of this form is frequently spiny, is an error due to the confusion 

 of nitidtts with rattus and other species. This confusion and such 

 errors were unavoidable so long as one had to work with nothing 



C^) For explanation of this cusp, nomenclature, see Barrett Hamiltom and 

 Hinton, British Mammals., Pt- xvi, p. 501, PI. 28 (1911). 



