NOTES ON SOME RATS OF THE MUS METTADA GROUP. 999 



The indications of a difference in size between the sexes are here 

 strongly marked. 



There is little to distinguish listoni from mettada, except the differ- 

 ence in the size of the molars, but this difference is quite constant and 

 easily appreciable even by the naked eye. 



3. Mus comberi sp. n. 



Outwardly resembling the two last species, but distinctly smaller. 



Unfortunately, all Mr. Comber's specimens are females. 



The following are dimensions of the four individuals : — 



134 



137 



140 



139 



Age and Sex 



Head and body 



Tail 



Hind foot - 



Ear 



Skull : greatest length 



„ basilar length 



„ zygomatic breadth. 



„ diastema 



„ upper molar row.... 



YA 9 



118 

 98 



22-5 

 20 

 32 

 27 

 15 

 9 

 5-7 



Type.— B. M. No. 7. 1. 7.3. An old 9 . Collector's No. E. C. 134. 

 Obtained by Mr. E. Comber at Nasik, and presented to the British 

 Museum by the Bombay Natural History Society. 



Its markedly inferior size, as compared with females, of the two pre- 

 ceding species, both of body and skull, make comberi easily distinguish- 

 able from either. 



I have pointed out that in the mammary formula and the plantar 

 pads these three forms are alike, and this applies also to their colour- 

 ation. The fact that the specimens I identify as Mus mettada and 

 those I name comberi were taken in the same locality and differ in the 

 size of the teeth justifies their specific separation. The specific 

 separation of comberi and listoni, however, must depend on the non- 

 existence of intermediates ; from my knowledge of the country I argue 

 that the discovery of such is most unlikely, and I have not hesitated, 

 therefore, to rank them both as species. 



An interesting point indicated, if not proved, by these two series is 

 the difference in the sexes. In listoni the males are markedly and 



