INFRODUCTION. 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. 1 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 but 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 twa oppusite 
stayes of color in one species, calling each by a different 
specific nume, and has afterwards found specimens that 
in their peculiar plumage, size, ete, 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 4 
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 Zurdine. 
We also have a Robin that is very light-colored, with the 
