k SHORT NOTE ON THE INDIAN .HATS. 7 



and of one or two which are ' house-rats of sufficiently wide dis- 

 tribution and common occurrence to make it important that they 

 should be definitely recognized. Of these a short account will be 

 given, non-technical as far as possible, but sufficiently full to make 

 their identification a simple matter. Mice I shall leave out of 

 consideration altogether, as although Mas muscu'lus has been 

 found infected in Australia, and although I have, as a rare excep- 

 tion, found mice dying of plague in Calcutta, I consider them of 

 very little practical importance. The third category as the most 

 important will be the first to be dealt with and will comprise the 

 following: — - 



1. Mus rattus, the Black Rat. 



2. Mus decumanus, the Brown Rat. 



3. Nesokia bengalensis, the Indian Mole Rat. 



4. Nesokia bandieota-, the Bandicoot Rat. 



5. Nesokia hardwlchii, the Short-tailed Mole Rat. 



6. Mus rutins var. nitidiis, the Hill Hmise Rat. 



7. Mus concolbr, the little Burmese Hat. 



Mus and Nesokia are two dosely allied genera of tke sub-family Murinse be- 

 longing to the family Muridoe. The chief distinction between Nesokia and Mus may 

 be broadly put as follows : the former are stout, heavily built rats with short, heavy, 

 broad heads, an arvicoline or vole-l:ke aspect, large feet and large molars in which 

 the division of the tooth into transverse laminae is much more marked than the 

 division of the sinuous laminae into cusps as it is found in Mus. 



1. MUS RATTUS -THE BLACK RAT OF ENGLAND. 



This is the common house-rat of India and the rat that is 

 the most important in the propagation of plague, as from its habits 

 it is brought into very intimate contact with man and is accord- 

 ingly more liable than any other to infect him through the 

 medium of its fleas. ]t is a slender rat with a very pointed muzzle, 

 large out-standing ears, large prominent eyes and a long tail, 

 as a rule 25 per cent, longer than the head and body. The feet 

 are of medium size but comparatively long and slender. In size 

 it is very variable, ranging from 14 cm. to 19 cm. in length of 

 head and body. In color it is very variable also, but the most 

 common type is a rather light rufescent brown with a white or 

 grey belly. The grey of the belly may be orange-grey or sprinkled 

 with fawn, and the white may be marked with a central stripe or 

 spot of grey. Sometimes the whole coloration of the lat may be 

 darker than usual, and the darkening may go so far that it is 

 black. This occurs in 30 per cent, of those found in Bombay, but 

 in Calcutta melanotic forms are rare. On the other hand, the 

 colour may be much lighter than usual, — -a pale yellowish or 

 cinnamon-brown, and this may be so extreme that the rat is found 

 yellowish, greyish or almost white. Though essent'a^y a house- 

 rat, living typically in the tiles of the roof, in the thatch, in holes 

 in the floor, recesses behind boxes and such like places, it may be 

 arboreal in which case it tends to be more slender, smaller and 



