STUDIES OF THE AMERICAN FALCONIDJI. 



By Egbert Eidgway. 



MOIs^OGRAPH OF THE POLYBORI. 



INTRODUCTION. 



The Polyhori are a group of American liawks of very peculiar appear- 

 ance and habits, and without near relatives in auy other portion of the 

 workl. Feeding largely upon carrion, while many of the species have 

 the head partly denuded of feathers, most authors have assigned them 

 a position near, or even amongst, the Vultures ; but recent investiga- 

 tions have proven that, while the^^ are true Falconidcc, they are at the 

 same time not only widely different from the American Vultures (a very 

 distinct family — the CatharUdce), hnt closely related to the Falcons proper, 

 to whose subfamily thej' belong, instead of that in which the Old- World 

 Vultures are placed. 



We have elsewhere demonstrated that the Falconidce are divisible into 

 but two subfamilies, the FalGonlmv and the Buteoniiuc, to the former of 

 which belong the true Falcons, besides the genera Mlcrastur and Herpe- 

 totheres, and the subjects of the i^resent paper; while to the latter belong 

 the Old- World Vultures and all other Falconidw. * 



The characters defining the two primary divisions of the family, and 

 which constitute them separate subfamilies, are more internal than exter- 

 nal, so that they can be distinctly diagnosed by the osteological structure 

 alone. The following diagnoses may serve for illustration of these wide 

 differences. 



A. — Scapular process of the coracoid produced forward so as to meet the 

 clavicle. Kasal bones almost completely ossified, the nostril being 

 a small, usually circular, opening, with a conspicuous, usually 

 central, bony tubercle. Inferior surface of the supramaxillary 

 with a prominent median angular ridge. Superciliary process of 

 the lachrymal consisting of a single piece.. Subfamily Falconince. 



B. — Scapular process of the coracoid not produced forward, but sepa- 

 rated from the clavicle by a wide interval. Nasal bones very 

 incompletely ossified, the nostrils large, without bony tubercle, 

 and frequently with an incomplete septum. Inferior surface of 

 the supramaxillary without median ridge. Superciliary process 

 of the lachrymal usually consisting of two pieces, joined by a 

 cartilaginous hinge Subfamily Buteoninw. 



The subfamily Falconince is composed of four well-defined groups, the 

 Falco7ies, Polyhori, Micrastures^ and Serpetotheres, which are distin- 

 guished as follows: 



"^ See " Outlines of a Natural Arrangement of the Falconidse," in Bull. No. 4, second 

 series, pp, 225-231, ills. s.i-xviii. 



