EXPLANATION OF PLATE VI. 



Diagram showing the weight-frequency of 3,000 house rats 

 of all ages which were caught in the neighbourhood of Amritsar. 



The figures on the base line represent a series of weights ascend- 

 ing by increments of 5 grammes from 15 to 250 grammes. 



The lengths of the upright lines are proportional to the num- 

 ber of rats of (or nearly of) each weight. The mean weight of the 

 adult rats is known approximately from the point at which the 

 uprights begin to diminish in length, on the right of the diagram. 

 It cannot be greater than 150 gms., although a few rats weighing 

 as much as 250 gms. were met with. 



It appears, therefore, that the normal range of weight- varia- 

 tion among the class is from 50 to 250 gms. A pregnant female 

 weighing 65 gms. was obtained. 



It will be noticed that the uprights are alternately long and 

 short ; this is due to the methods employed, and is of no significance. 

 The rats were weighed with a spring balance, recording to 5 gms. 

 The occasional difficulty of deciding between fives and tens must 

 have been too often decided in favour of the latter. 



The diagrams have been constructed from records provided 

 by Capt. Davys. 



