1850.] Remarks on the variation of affined species, 221 



Remarks on the modes of valuation of nearly affined species or races 

 of Birds, chiefly inhabitants of India. — By E. Blyth. 



The drawing up of a catalogue of species of any class of animals 

 involves a series of decisions as to what are to be considered species or 

 merely varieties of the same species, in all of which decisions no 

 two zoologists will be found to agree, inasmuch as in numerous cases 

 of difficulty such decisions become quite arbitrary. The fact is, we 

 find every variety of gradation from a similitude which does not permit 

 of a distinction being made, to an amount of discrepancy which all 

 would agree in regarding as of specifical import. As species are often 

 represented (I do not use this word in reference to a system of repre- 

 sentation, in which I do not believe,) in distant countries by others 

 bearing a greater or less resemblance to them, in some cases so close as 

 scarcely to permit of discrimination, so there may be others having 

 equal claim to be regarded as of distinct origin, even though utterly 

 undistinguishable apart. Or a particular age or sex only may present 

 some marked diversity, as instanced by the caterpillars of certain 

 lepidopterous insects which are hardly, if at all, to be separately recog- 

 nised in the imago phase of their existence. Mr. Swainson collected 

 in Brazil specimens of a butterfly, Papilio (Fodalirius) nomius, 

 figured in his 'Zoological Illustrations,' which would hardly be 

 supposed to inhabit likewise Lower Bengal ; yet a species which, so 

 far as can be judged from his very careful representation, is absolutely 

 similar, abounds in the vicinity of Calcutta and other parts of 

 Bengal during the dry hot season. It is true that we also get here 

 the Cynthia cardui, which is a butterfly of almost universal distri- 

 bution, alike in the British islands, America, and Australia i* but it 

 does not appear that Papilio nomius has been observed elsewhere than 

 in India and Brazil, and we can hardly suppose its race to have been 

 conveyed from one of these countries to the other, or to have reached 

 them both from a common point of divergence. 



* We have compared specimens from Calcutta, Central India, the E. and W. 

 Himalaya, and Afghanistan, with others from Europe and W. Australia, and could 

 detect no distinctive character whatever. 



2 G 



