266 C. A. GOURLAY: The Rats of Dacca. [Vol. I, iQoy.] 



Ears. — The ears, though in actual measurement not appre- 

 ciably shorter than those of M. rattus, are more closely set on the 

 side of the head. These also show gradually diminished propor- 

 tionate measurement as age advances. 



Breasts. — The commonest distribution of breasts was found to 

 be ^. This arrangement was found in 61*5 per cent, of the female 

 specimens with breast development. In only 8*3 per cent, was the 

 arrangement f present. The arrangement is certainly much more 

 variable than in M. rattus. 



Distribution. — Of all specimens of N. hengalensis— 



29 % were captured in " pucca " houses. 

 29-3 „ „ „ " kutcha " „ 



15-5 „ „ ,, grocers' shops. 



2i'2 ,, ,, ,, grain godowns. 



5 „ „ „ streets, etc. 



Most of these observations agree with those of Hossack in 

 Calcutta. They confirm (i) the impossibility of separating varieties 

 of M. rattus by size. 



(2) The size at which maturity is attained, namely 14 cm. in 

 both species. 



(3) The diminution in the proportionate measurement of 

 hind foot and ear in both Mus rattus and Nesokia hengalensis ^ and of 

 the tail in Mus rattus^ as maturity is reached. 



On the other hand, I do not find the distinction between cor- 

 diform median pads in Mus rattus and circular median pads in 

 Nesokia hengalensis holds good. The essential point of difference 

 appears to me to be the rudimentary condition of the proximo- 

 external pad in the hind foot of N . hengalensis. Again, Hossack 

 gives the usual breast arrangement of Nesokia hengalensis as \. 

 I find it is ~. 



