,'io6 JOURNAL, BOMBAY NATURAL HIiST. SOCIETY, fot. XXL 



As regards the genera themselves Bingham and Seitz agree 

 fairly well and where they differ, Seitz, who reviews the butterflies 

 of the world, has usually been followed. Many of Moore's genera 

 have been used as sub-genera ; genera are thus rendered more 

 comprehensive and natural groups within them kept separate. 



The word "species " has been a source of miich contention and 

 Bingham substituted the word " form" for it, an indefinite term 

 meaning anything from a species to a slight variety. The matter 

 does not seem to present any great difficulty as long as it realised 

 that a local race may develop into a species and eventually into a 

 genus, that no hard and fast rule is laid down and that this 

 development may be encountered at any stage. For ordinary 

 purposes a species may be defined as a group of individual forms 

 that resemble one another more or less and are capable of freely 

 interbreeding with one another but normally refuse to breed with 

 any other species. 



A species spread over a wide area may develop into a number 

 of more or less well defined local races and more especially so if 

 geographical obstacles intervene. Migratory species like the 

 Oatopsilias and Polyommatus bceticus are always intermixing, thus 

 preventing the formation of local races. Weak flying hill species 

 separated by intervening plains are almost certain to develop into 

 races and perhaps eventuallj^ into new species ; thus the Nilgiri 

 Oolias is a race of the Himalayan Colias lativitta which itself is a 

 race of the European Oolias hyale. 



A local race may eventually develop into a species, but when a 

 race actually becomes a species it is impossible to say. Many 

 entomologists affirm that if the male organs of two forms are alike 

 they are conspecific and vice versa, if the male organs differ they 

 belong to two species ; this does not seem to follow necessarily and 

 the only real test would be to put several individuals of one race 

 with several individuals of another race and watch if interbreeding 

 occurred. In many instances grading between races is apparent 

 where the boundaries of their respective areas meet, but where 

 some geographical obstacle intervenes this is impossible. 



It is assumed here that where two forms inhabiting separate 

 areas resemble each other fairly closely, though differing in certain 



