FALCONID^— DIURNAL EAPTOEES. 427 



I am not fully satisfied of the advisability of according Pandion 

 the rank of a family but am rather inclined to look upon it as 

 constituting a subfamily of a family Buteonidce. The reversible toe 

 and the peculiarly compact plumage, which are apparently its most 

 marked characters, are certainly teleological modifications, fitting 

 it perfectly for its piscatorial habits. In other characters, both 

 anatomical and external, it exhibits numerous points of analogy, 

 if not relationship, to the genera Elano'ules and Elanits, and 

 it seems to me should be placed at least as near to these forms as 

 they are to any of the Buteonine genera. 



Subfamily FALCONIN-ffi. 



Chae. (See page 426.) 



The Falconinse, as here recognized, include not only the true 

 Falcons {Falconeo'), but also three other groups, each of which is 

 peculiar to Middle and South America. They may be distinguished 

 as follows : 



A. Posterior. toe abbreviated, very mueh shorter than the lateral pair; tarsi and 

 toes covered'with small hexagonal scales, larger in front. 



a. Nostrils a small, round, or oblique opening, with a bony-rimmed margin 

 and central tubercle. 



1. Superior toniium with a conspicuous tooth, and inferior tomium with 

 a corresponding notch. Superciliary process of the lachrymal elon- 

 gated, narrow, reaching nearly across the orbit. Posterior margin of 

 the sternum'nearly even, with a pair of large oval foramina. One or 



two outer primaries with inner webs emarginated near theirtips. .i^a?oonp«. 



2. Tomia without tooth or notch. Superciliary process of the lachrym.l 

 abbreviated, reaching only half-way across the orbit. Posterior mar- 

 gin of the sternum with a pair of deep indentations. Three or more 

 outer primaries sinuated near the middle portion Polyhorecv. 



h. Nostrils a large opening without bony-rimmed margin or central tubercle. 



.3. Superciliary process of the lachrymal elongated, broad, extending 



nearly across the orbit. Tomia without tooth or notch. Posterior 



margin of the sternum as in Falconece. Four or more outer primaries 



with inner webs sinuated near the middle portion Micrasturece. 



B. Posterior toe elongated, almost equal to the lateral pair. Tarsi and toes cov- 



ered uniformly with thick, rough, imbricated scales. 

 4. Tomia without tooth or notch. Nostrils as in'Falconece a,nfi Polyhorece. 

 Superciliary process of the lachrymal elongated, very broad, reach- 

 ing nearly acros.s the orbit. Posterior margin of the sternum nearly 

 even, entire, and without foramina. Primaries as in Polyborew and 

 Micrastureie Berpetotherece. 



