EXPLANATION OF PLATE I. 



Fig. I. — Two specimens of Mus rattus showing w^hite breast 

 stripes. One was found at Bombay and the other at 

 Madras city ; both were selected from among large num- 

 bers of the common rats of those cities. Individual rats 

 showing this character have also been obtained from 

 Calcutta and Nowgong. 

 Quite recently I obtained at Poona a litter of four 

 young rats and an adult, all of which resembled the 

 specimen on the left of the figure. The common rats 

 of Poona are uniformly coloured below. 

 It appears, therefore, that this character is definite 

 in Mus rattus, and that it appears independently 



^ among the rats of widely separate localities and is 



heritable. 



Fig. 2 — a. Tail of a normal Mus rattus for comparison. 



b. Side view of the tail of one of the Ayapata race 

 (p. 42). This is one of the several types of tail 

 coloration found among this race. The others are 

 shown in plate iv. This particular type resembles, in 

 the pigmentation of its tail, Mus berdmorei, a " species " 

 recorded from Manipur and Tenasserim. 



c. Side view of the tail of one of the sports also shown 

 in fig. 3. The change from the pigmented to the un- 

 pigmented skin is abrupt. At the junction the white 

 area invades the dark area in an irregular manner. 

 Some specimens of Mus blanfordi which have been 

 preserved in spirit show a precisely similar appearance 

 Sit the junction of the coloured and colourless portions 

 of the tail. 



Fig. 3. — Heads of the two abnormal Mus rattus found .near 

 Amritsar (p. 22). The tails of these rats were as 

 alike as their heads ; one of them is shown above 

 (fig. 2C). 



