90 



Records of the Indian Museum. 



[Vol. Ill 



The circumstances of case 8 are different from those of case 7. 

 In case 7 the chief peculiarity, blackness, which marks off the ten 

 rats from the race out of which they have presumably arisen, is 

 remarkably constant in degree. In case 8 the feature, bicoloration 

 of the tail, which marks off the group, is so variable that at least four 

 distinct ' ' types ' ' are present among the eight. It appears that 

 a parallel case to this has been recently published. In Hossack's 

 ''Account of the Rats of Calcutta" is an illustration which is 



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') -J 



Fig. 9. — Illustration of variation in belly colouring in Mus ratttis (after 

 Hossack). 



reproduced here (text-fig. 9) ; this is accompanied by the following 

 statement : ''As showing how endless are the combinations and 

 variations of these different belly colourings, the figure in the text 

 may be referred to, showing the different variations found in nine 

 specimens of M. rattus, which represented the total bag for one 

 day." 



The concluding clause of this quotation is an important part of 

 it. Having examined a certain number of the Calcutta rattus, the 



