INTRODUCTION. 85 



study these seeming distinctions, and decide if they are 

 constant. 



Specific characters are, I believe, sufficiently tangible 

 and constant in nature, and never need be mistaken ; this 

 will hereafter be illustrated. I would, however, first speak 

 strongly in disfavor of the growing belief in the hybridism 

 of birds. I do not believe that, generally speaking, hybrids 

 occur ; there are a few cases, but they are exceptions. In 

 many instances the so-called hybrids are bat abnormal con- 

 ditions of plumage, that can be accounted for on entirely 

 natural grounds. But sometimes the ornithologist, in his 

 haste to make new species, has divided the two opposite 

 stages of color in one species, calling each by a different 

 specific name, and has afterwards found specimens that 

 in their peculiar plumage, size, etc. naturally form con- 

 necting links between the two; in his perplexity as to 

 which of these to refer it, he has hit upon the fortunate (?) 

 expedient of calling it a "hybrid." Would it not have 

 been much better, if, at first, he had taken a large num- 

 ber of specimens, and, studying them, seen what the sup- 

 posed hybrids really were % 



I have yet to meet with a single instance of hybridism 

 even among local races, although these perhaps occur — 

 but, I think, seldom — among well-defined species while 

 undomesticated. 



Species consists in a bird's having certain characters so 

 well defined, although inconstant (but never variable beyond 

 a certain point), that it may readily be distinguished from 

 others. Take, for an illustration, the Robin, a bird that 

 since its discovery has never had a single variety or local 

 race called a "new species" (at which I marvel greatly, how- 

 ever). The typical specimen has a clear red breast, black 

 head, and immaculate slate-colored back and wings, which 

 at once distinguish it from all others of the Turdinoe. 

 We also have a Robin that is very light-colored, with the 



