142 Mr. H. E. Dresser. 



the interbreeding of allied species, and has some interesting 

 series of examples, amongst which the most interesting are, 

 in my opinion, the series I now exhibit, showing that the 

 Asiatic and European Goldfinches interbreed where they meet. 

 Our common Goldfinch (Carduelis elegans) does not vary 

 throughout Europe except that in the extreme east examples 

 are rather larger and have more white on the nape and fore 

 part of the back, and the rump and upper tail coverts are pure 

 white. In most parts of Asia, however, our bird is replaced 

 by a perfectly distinct species, Carduelis caniceps, and until 

 lately no specimens showing a gradation between the two 

 species had been recorded, but a series of specimens from a 

 part of Central Asia where the two species meet has been 

 sent over (and which I exhibit here), which clearly shows that 

 there they interbreed as much as the two crows do, and it is 

 clear that the offspring is fertile as will be seen by the extreme 

 variation shown in the specimens before you. It may, however, 

 be quite as possible that the original stock of the two species 

 was a bird intermediate between the two, inhabiting that part 

 of Asia, and that the two forms have spread out from thence, 

 one to the eastward merging in the course of time into 

 Carduelis caniceps, and the other migrating to the westward 

 and becoming Carduelis elegans. 



As regards the species which have been evolved by a long 

 continued isolation from the original stock the most interesting, 

 and those which may be cited as most clearly proving this to 

 be the case, are island forms. Thus in Great Britain we have 

 two species which are peculiar to the islands, Lagopus scoticus, 

 our common Red Grouse — which differs from the continental 

 Lagopus alhus in never becoming white in the winter, but 

 which at some distant period was doubtless identical with the 

 continental form — and Parns britaunicus, a form of Paru ater 

 differing from, that species in having the upper parts olivaceous 

 instead of blue grey, but which is also, doubtless, a form 

 evolved by long-continued isolation. Our Dipper, also, being 

 non -migratory, differs also almost enough from the continental 

 species to be raised to specific rank. 



In the Atlantic islands (Madeira, the Canaries, and Azores) 

 there are many more species which have become distinct by 

 continued isolation, as for instance Cypselus unicolor, Regidus 

 maderensis, Anthus berthcloti, Fringilla tintillon, Serinus 

 canarius and Pyrrhula murina, the last being one of the most 

 interesting, for it resembles the female of Pyrrhula europoea, 

 but whereas the male of the latter species has the underparts 

 always red, the male of Pyrrhula murina differs but a little 

 from the female, and resembles the female o{ Pyrrhula etiropcea 

 not a little. 



