MOLOTHRUS RUFOAXILLARIS. 93 



has occurred to me is that M. badim is sagacious enough to distinguish 

 the eggs of the common parasite, and throws them out of its nest. 

 But this is scarcely probable, for I have hunted in vain under the 

 trees for the ejected eggs ; and I have never found the eggs of M. 

 badius with holes pecked in the shells, which would have been the case 

 had a M. bonariensis intruded into the nest. 



With the results just recorded I felt more than satisfied, though so 

 much still remained to be known ; and I looked forward to the next 

 summer to work out the rich mine on which I had stumbled by chance. 

 Unhappily, when spring came round again ill-health kept me a prisoner 

 in the city, and finding no improvement in my condition, I eventually 

 left Buenos Ayres at the close of the warm season to try whether 

 change of climate would benefit me. Before leaving, however, I spent 

 a few days at home, and saw enough then to satisfy me that my 

 conclusions were correct. Most of the birds had finished breeding, 

 but while examining some nests of Anumbius I found one which Bay- 

 wings had tenanted, and which for some reason they had forsaken 

 leaving ten unincubated eggs. They were all like Bay-wings' eggs, 

 but I have no doubt that five of them were eggs of M. rufoaxillaris. 

 During my rides in the neighbourhood I also found two flocks of Bay- 

 wings, each composed of several families, and amongst the young birds 

 I noticed several individuals beginning to assume the purple plumage, 

 like those of the previous autumn. I did not think it necessary to 

 shoot more specimens. 



The question, why M. badius permits M. rufoaxillaris to use its 

 nest, while excluding the allied parasite, M. bonariensis, must be 

 answered by future observers ; but before passing from this very 

 interesting group (Molothrus] I wish to make some general remarks on 

 their habits and their anomalous relations to other species. 



It is with a considerable degree of repugnance that we regard the 

 parasitical instincts in birds ; the reason it excites such a feeling is 

 manifestly because it presents itself to the mind as to use the words 

 of a naturalist of the last century, who was also a theologian, and 

 believed the Cuckoo had been created with such a habit " a monstrous 

 outrage on the maternal affection, one of the first great dictates of 

 nature." An outrage, since each creature has been endowed with this 

 all-powerful affection for the preservation of its own, and not another, 

 species ; and here we see it, by a subtle process, an unconscious iniquity, 

 turned from its purpose, perverted and made subservient to the very 

 opposing agency against which it was intended as a safeguard ! The 

 formation of such an instinct seems indeed like an unforeseen con- 

 tingency in the system of nature, a malady strengthened, if not 



