INTRODUCTION. XXvii 



own, or tending to revert to a supposed original type. 

 That various nearly affined species will propagate, inter se, 

 and produce fertile offspring, I fully believe ; as in the cases 

 of the green Pigeons of Bengal and of Southern India ; in the 

 Indian and the Burmese Rollers ; the small Cuckoos of S. 

 India and those of Bengal ; and in several other instances : 

 but that this fact militates against their being species, and 

 in favor of tlieir being varieties, I think is not supported 

 by many recent experiments in crossing. Of late years 

 many species have been universally admitted, as such, 

 which were formerly considered simple varieties, and, 

 although, perhaps, the tendency of late writers has been to 

 multiply species, in some cases most unnecessarily, yet in 

 previous years the other extreme was taken, more especi- 

 ally by Schlegel and his followers. Our best naturalists 

 and ornithologists now fully recognize the distinctness of 

 permanent races. If varieties are once allowed, it depends 

 on individual judgment or caprice to what extent they 

 may be carried. In this country, where there are many 

 very closely allied species, among genera characteristic of 

 the country, many of the species of Malacocircus and 

 Hoematornis would be classed as simple varieties by some, 

 whilst others would perhaps allow some of them, whose 

 different notes they might have observed, to be distinct 

 species ; and the rest varieties. Lastly, it is, I think, more 

 convenient in practice to give each race a distinct specific 

 name, than to speak of them as Var. A. or Yar. B. of 

 such a species. 



It is beyond the scope of the present introduction to en- 

 ter into the question of the origin of affined species. They 

 may, originally, have sprung from type species, as Darwin 

 teaches, and remained permanent in such localities as 

 suited them, and not in others; or, they may have at once 



