( B7 ) 



ON THE VARIATION OF SPECIES. 

 By H. W. Bates. 



[Extracted from The Naturalist on the River Amazons, vol. i., pp. 25-5 — 



265.1 



A GENERAL resemblance of the species to those of Guiana 

 is one of the principal features in the Zoology of the 

 Amazons valley; but in the low lands a great number exist 

 only in the form of strongly modified local varieties; indeed, 

 many of them are so much transformed that they pass for 

 distinct species, and so they truly are, according to the re- 

 ceived definitions of species. In the somewhat drier district 

 of Obydos, the forms are more constant to their Guiana 

 types. We seem to obtain here a glimpse of the manufac- 

 ture of new species in nature. The way in which these 

 modifications occur merits a few remarks ; I will therefore 

 give an account of one very instructive case which presented 

 itself in this neighbourhood. 



The case was furnished by certain kinds of handsome 

 butterflies belonging to the genus HeUconiuSj a group pe- 

 culiar to tropical America, abounding in individuals everv- 

 where in the shades of its luxuriant forests, and presenting 

 clusters of varieties and closely-allied species, as well as 

 many distinct, better marked forms. The closely-allied 

 species and varieties are a great puzzle to classifiers, in fact, 



