XXI.— NOTE vS ON THE RATS OF DACCA, 

 EASTERN BENGAL. 



By C, A. GoiTRLAY, Captain, IM.S. 



I forward these notes to the Indian Museum as a small con- 

 tribution to a subject of considerable importance at the present 

 day. 



During the month of April, 1907, an attempt was made to 

 gauge the relative numbers of different species of rats in Dacca. 

 During the investigation, 1,045 ^^ts were examined and of these 

 1,041 were identified. 



611 proved to be specimens of Mus rattus. 



430 ,, ,, ,, ,, Nesokia bengalensis. 



No other species of rat was found. Thus of the rat population 

 of Dacca, it appears that about 59 per cent, are Mus r alius and 41 

 per cent, are Nesokia bengalensis. 



These specimens were trapped in houses, " kutcha " (mud) 

 and " pucca " (masonry), and in grain godowns and grocers' shops 

 in various parts of the town. 



Of those trapped in 



Dacca is a city of over 90,000 inhabitants, with narrow streets, 

 indifferent sanitation, a very imperfect system of surface drains, 

 and only one short sewer. Many of the houses are " kutcha " 

 throughout, and of the " pucca " houses many have earthen floors. 



In all cases, measurements were taken in accordance with 

 Hossack's instructions and the collection was divided into three 

 series of about 350 specimens each. The first series is omitted 

 from these observations as, presumably, the measurements (being 

 those of a novice) are not so accurate as the later ones. 



M. RATTUS. 



It was found impossible to distinguish the varieties of M. 

 rattus according to the descriptions extant. All sizes show colour 

 variations and the only point on which one can dogmatise, is that 

 M. rattus — the black rat — does not appear to be black in Dacca. 



