30 RIDGWAY’s catalogue of north AMERICAN BIRDS. 
want of sufficient material to decide the question of intergradation 
or the contrary. 
“ Every form whose characteristics hear iinmistakeably the 
impress of climatic or local influences, gradually less marked 
toward the habitat of another form, with which it thus inter- 
grades, and all forms which certainly intergrade, no matter how 
widely distinct the opposite extremes may appear ( e. g., Colaytes 
Auratus and C. Mexicaniis, and the different races of Passerella), 
together with intergrading forms whose peculiarities are not 
explained by any known ‘law’ of variation, have been reduced to 
subspecific rank (and distinguished by a trinomial). 
“ On the other liand, where the difference between allied 
forms is slight, but at the same time apparently constant, and 
not necessarily coincident with a difference of Iiabitat, specific 
rank is uirlield.” 
I cannot help thinking that this adoption of a trinomial 
system of classification marks a very decided advance on our 
older methods of classification. There has been of late a great 
tendency amongst systematic ornithologists to increase the 
number of species to an alarming extent ; every little local 
variation has been taken to justify a new specific appellation ; 
as, for instance the division of the Bi’itish forms of “ Gole 
Titmouse,” “Long-tailed Titmouse,” and others, from the 
European forms of the same species (as in Dresser’s magnificent 
work). 
Anyone who is accustomed to seeing a large number of 
specimens of any British- European species cannot fail to remark 
a very decided difference in the two forms. I have often noted 
how easily I could pick out European specimens of “ Marsh 
Titmouse,” “ Creeper,” “ Tawny Owl,” “ Common Heron,” and 
others, from amongst British specimens of the same species ; 
they have a decidedly distinct character, generally the colours 
