I907.J 



Dr. Hossack : The Rats of Calcutta. 

 Skull Measurements in Millimetres. 



35 





Extreme 

 length. 



Zygomatic 

 breadth. 



Length of 



Up. Molar 



Series. 



Breadth of 



Up. Molar 



Series. 



Length 



Ant. Pal. 



For. 



Average of — 











6 Nesokia kok (Ind. Mus.) 



36-6 



22-4 



7-2 



2-54 



7-3 



20 ,, èewg'. (Hoss. Coll.) . . 



40-2 



23-8 



7-14 



2-6 



7-1 



10 ,, ,, (Ind. Mus.) .. 



42-2 



26 



8 



3 



7-8 



Maximum of — 













6 Nesokia kok (Ind. Mus.) 



? 



24 



7-5 



2-75 



8 



20 ,, ôeng. (Hoss. Coll.) . . 



44 



25-7 



8 



3 



8-5 



10 ,, ,, (Ind. Mus.) . . 



47 



28 



9 



3-2 



10-5 



Minimum of — 













6 Nesokia kok (Ind. Mus.) 



35-5 



21-5 



7 



2-5 



7 



20 ,, fteng. (Hoss. Coll.) .. 



37 



22-5 



6-5 



2-3 



6-5 



10 ,, ,, (Ind. Mus.) 



39 



23-5 



7 



3 



7 



Interbreeding of Nesokia bengalensis with Mus decumanus. 



Anderson records a very striking observation as to the interbreeding of Nesokia 

 hlythianus (i.e., bengalensis) with Mus decumanus , which had better be reproduced in 

 his own words : — 



" Among males found among the native huts I have observed two types of skulls, 

 ''one larger than the typical form, but the animals were in other respects identical 

 ** with other males conforming to the ordinary type of skull. I have never observed 

 " these more elongated skulls in females, but, if they do occur, I would be disposed 

 " to make the variation due to interbreeding with Decumanus."^ 



I am able to confirm this observation more or less, for I have come across one 

 very large specimen. No. 328, which in some points of the skull suggested an admix- 

 ture with M. decumanus , though I must admit that on the indication given by the 

 smallness of the foot, the thinness of the fur and the general appearance, there was 

 nothing against it being an exceptionally large specimen of unmixed Nesokia benga- 

 lensis. The following is a detailed description : — 



Crossbred (?) Nesokia bengalensis, No. 328. 



Head and body. Tail. Hind foot Ear. 



255 19 35 2-45 



1 Anderson, loc. ante cit., p. 228. 



