1909.] 



R, K. Ivi^OYD : The Races of Indian Rats. 



69 



Type B — Black variety. — These are not so common, pure black 

 ones making up less than one per cent, of the whole ; semi-melanotic 

 specimens are more common. The melanotic and semi-melanotic 

 examples of Mus concolor show exactly the same gradations of 

 colour as are exhibited by Mus rattus (Hossack [i, page 17]). 



Type C — The white-bellied type. — The writer did not himself 

 meet with any adult rats of 120 mm. length of the white-bellied 

 type. The 500 measurements received from Captain Kelsall show, 

 however, that they are to be found; each measurement was accom- 

 panied by a statement that it was of a rat which was sexually 

 mature. These small white-bellied rats might be considered as 

 exceptionally small members of the race next to be described. 



The figures beneath the horizontal line in text-fig. 8, which show 

 the numbers of white-bellied rats of each measurement which are 



140 



120 



100 



80 



60 



40 



20 



11231214 1 



i I i 



100 120 150 175 



Fig, 8. — Diagram showing the length-frequency of 500 Mus concolor and 

 white-bellied Mus rattus from Rangoon (Kelsall). 



present, seem to indicate that some of them, for example the one 

 measuring 115 mm., should be regarded as white-bellied Mus con- 

 color. A point of distinction is always present in the case of 

 females, for no exception was found to the rule that the teats in 

 Mus concolor were eight in number (|). The dark-bellied rat 

 shown as measuring 170 mm. length was probably a recent 



