1909.] R. E. Lloyd : The Races of hidian Rats. 



19 



and Punjab measurements, 10 mm. was added to the tail length 

 and subtracted from the length in the latter series ; even after this 

 ver}' liberal allowance had been made, the difference between the 

 Punjab and Calcutta race is ver}^ apparent. Hossack's measure- 

 ments show that the mean tail length of the Calcutta race averages 

 125 % of the length. As mentioned before, the Punjab collection 

 was received in batches of about twenty individuals, each batch 

 being collected on a different date and often from a separate 

 village. After making the allowance of ± 10 mm., the average tail 

 percentages of the groups vary from about 115 to 120. One or two 

 exceptional batches, however, show lower values. Lot D, C. shows 

 the lowest of all. 



The measurements were all taken b}' the same hand, all in- 

 dividuals received in each batch were included except those the 

 length of which was less than 160. Small and young rats were 

 excluded, because the ± allowance of 10 mm. would fall too heavily 

 upon them ; and because young rats have proportionately longer 

 tails than adults (Hossack). Among the different batches from the 

 Punjab, the Lot L. T. shows one of the highest average tail per- 

 centages ; Lot D. C. the lowest. The average percentage of all the 

 500 was not calculated, as it would not accurately represent the 

 value in the whole race. It must be about 117 



The writer considers that the above figures show firstly, that 

 the tail percentage of mixed Punjab rats is lower than the same 

 value in Calcutta rats; secondly, that as regards tail length the 

 Punjab rats are not a thoroughly mixed race. The great difference 



