igog.] R. E. Lloyd : The Races of Indian Rats. 87 



and widely distributed animals. During the enquiry- several matters 

 of general biological interest have made themselves felt. 



The chief interest lies in the large number of sports which 

 have been met with ; that is to say of individuals which differ 

 widely in some character or characters from the race in community 

 with which they were found, although otherwise closely resembling 

 that race. The dift'erences which characterise these sports are of 

 colour for the most part ; they are, however, in some cases, of a wider 

 degree than the slight differences which are used at the present 

 day to separate species. It is unusual to examine any race of 

 animals in large numbers without meeting with sports both of 

 colour and of form, but the peculiar interest of this enquiry lies 

 in . the several instances in which such sports have appeared in 

 groups. Some of them have been met with singly, others as pairs 

 caught together in the same trap, others in " litters ' ' all the mem- 

 bers of which agree in differing from the normal race in the same 

 wa}' and nearly to the same extent. Finally, two cases have been 

 met with of rats, which can hardly be considered as other than 

 sports, occurring in groups large enough to occupy two adjacent 

 houses to the exclusion of other species of rats. The members of 

 such groups must be of close blood relationship, — in fact, " family 

 groups ' ' prone to inbreeding. 



Moreover, there are two examples of what appear to be the 

 same kind of sport having arisen independently in two far distant 

 localities. These similar sports are in one case from Bombay and 

 Madras, and in the other from Rangoon and Naini Tal. The former 

 places resemble one another in climate. The latter places are 

 utterly different from one another. 



Although many examples of sports have been already des- 

 cribed, the most important ones will be reviewed here. 



Cases of sinc^le sports. 



Case I.— The rat " Mds. 2 " is a Mas rattus; its ventral surface 

 is dark brown, and in the middle line of the breast is a pure white 

 streak. It was selected from among about 600 freshly killed rats 

 of the rattus type, which were received during two days. 



Case 2.- — A black example of the ratttts type caught in the 

 Museum of the Bombay Natural History Society where it at- 

 tracted attention owing to the pure white line on its breast. Al- 

 though this line is not quite so long as in the last case, it seems to be 

 essentially the same variation. A large proportion of the Bombay 

 rats are of the black type of rattus. The same variation has also 

 been noticed in Calcutta and at Nowgong. 



Cases I and 2 are shown side by side in plate i. 



Case 3. — One Mus rattus from the Punjab which shows a white- 

 tipped tail, with some lengthening of the terminal hairs of that 

 appendage. This case is specially mentioned because of the con- 

 comitant lengthening of the hairs. There are several examples 

 of w^hite-tipped tails among other .s])ecies of Guiionivs, I>aiidicota,, 



