THE GROWTH OF GROUPS 



69 



which renders them conspicuous. So conspicuous are 

 they among the others that it was the custom of the 

 Plague Commissioners to refer to them by the name of 

 Mus alexandrinus, as a nominal distinction from the 

 common Mus rattus. This is in accordance with the 



MAP OF POONA CITY. 



The group of houses mentioned in the text is indicated by dots in the 

 centre of the map. 



modern use of the word " species," two animals which 

 appear different from one another at a glance being 

 usually considered as of different species. The name M. 

 alexandrinus, as used in this particular case, might, 

 however, be regarded by a systematist as incorrect ; it 



