1917.] Chapman, Distribution of Bird-life in Colombia. 175 



temperate North America and temperate South America, while no species 

 of the group is. found in the intervening region. 



An Avocet {Recurvirostra) and Ridgway's Glossy Ibis (Plegadis), for 

 example, are found on the highlands of Bolivia and Peru, but the first 

 genus is not encountered again south of Guatemala (where it is found only 

 as a winter visitant from further north) and the Glossy Ibis {Plegadis autum- 

 nalis), a close ally of the Peruvian species, has not been recorded from south 

 of the United States. 



The distribution of Flickers presents a similar case. Found throughout 

 North America south to Guatemala they occur again on the highlands of 

 Peru, but are unknown in the intervening countries. 



It is now proposed, however, to remove the Flickers of the Peruvian 

 highlands from the genus Colaptes on the basis of their larger, heavier bill 

 and shorter wing, and while it is true that these characters are obvious, I 

 feel that the even more obvious and striking resemblances between the birds 

 of North America and those of South America call for recognition under a 

 common generic name. 



I am not unfamiliar with the perplexing problems which confront the 

 systematist. The treatment of the Chilian and Brazilian members of this 

 group' of Flickers is a case in point. I know from experience how difficult 

 of consistent application is a nomenclature which insists that definite lines 

 be drawn where only indefinite boundaries exist; but I maintain, to quote 

 the title-page motto of the American Ornithologists' Union's 'Check-List,' 

 that " Zoological nomenclature is a means, not an end, of Zoological Science," 

 and that any procedure which tends to defeat this end must handicap the 

 branch of science to which it is applied. 



Treatment of Subspecies. — Believing that classification is designed to 

 show relationships rather than to serve the ends of the classifier, I have 

 aimed to treat each case involving the use of a trinomial name on its own 

 merits with reference to the factors involved. To refuse to use trinomials 

 until the actual intergradation of the forms concerned is proven, is, in my 

 opinion, as undesirable as to make every supposed representative form a 

 subspecies. 



To lay down a certain rule and blindly be governed by it, is to handicap 

 one's discrimination and experience. Everyone accustomed to handling 

 large series of specimens knows that complete intergrads^tion remains to be 

 demonstrated between many of our familiar birds whose subspecific standing 

 is undoubted. The degree, and particularly the character of the differences 

 exhibited, range, environment, faunal areas, the relative plasticity of the 

 species in question, the action of other organisms in the regions concerned 

 under similar circumstances, these and other factors such as habits, voice, 



