MISCELLANEOUS NOTES. 4i7 



so on. Their fur also was too fine for Mus decumanus. My eighteenth 

 rat was quite a different creature. On the upper parts its colour was 

 a richer and more reddish-brown, while all the under-parts were pure white, 

 and the feet were pink. But there were other differences also, besides those 

 of colour. Its face was much rounder, its snout not so long, and its eyes 

 very large and beautiful. In fact, it looked quite a different animal. This 

 form has also been familiar to one for many years as a species of jungle, 

 or tree, rat, only coming into houses occasionally ; but while we had only 

 Jerdon's and Sterndale's books to go by, it was impossible to identify it 

 with certainty. I put it down as probably JIus brunnens. The ''Fauna of 

 British India" lias swept away all doubt. It is another form of Mus rattus, 

 the Black Rat. In fact, it would seem that Mus rattus may be regarded as 

 a semi-domesticated animal, like the pariah dog, in the case of which 

 colour and size count for nothing. But, in this view there is still a 

 difficulty to be explained. Why did I get seventeen of one form and one of 

 the other, instead of three or four of each and half-a-dozen inter- 

 mediate ? And this argument does not rest on these eighteen speci- 

 mens, for, as I have said, both forms have been familiar to me for 

 many years, and are as distinct in my mind as the two species of crowa. 

 If they refuse to intermix, and so keep up their distinctness, and yet 

 are the same species, then what constitutes a species V It is rather 

 significant that in the same museum where Mr, Thomas is classing 

 rats by the measurements of the skull, and treating colour and out- 

 ward appearance as of no account, the pillars of the entomological 

 department are splitting our most familiar butterflies into a multipli- 

 city of species distinguished by the brightness of a spot, or the 

 breadth of a "fascia," However, it was not to dispute Mr, Thomas' 

 conclusions that I took up my pen ; but I think that, in view 

 of them, it would be interesting to collect more information than we 

 yet possess about the dift'erent varieties which make up the rat population 

 of Bombay, and the numerical importance of each variety. It would be 

 particularly interesting to know to what extent the real Brown Eat {M. decu- 

 manus') has settled among us and dispossessed the other. This question 

 has a practical bearing in connecticn with the plague, for the Brown Eat 

 I believe, like the Bandicoot, lives mostly on the ground, and is very much 

 at home in sewers, though it can climb well when it hkes, which the 

 Bandicoot cannot do ; while the Black Eat is by nature an inhabitant 

 of trees, and, when it comes into a house, always lives in the 

 roof. 



1 may mention that all my eighteen rats were males. This throws a sad 

 light on the social life of the rat. The significance of it is, I believe, that 

 the in other has to seek remote and secluded places to bring up her family 

 lest their own parent should find them and eat them. Eabbit fanciers know 



