452 



A. — Posterior toe abbreviated, very much, shorter than the lateral pair; 

 tarsi and toes covered with small hexagonal scales, larger in front. 

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

 margin and central tubercle. 



1. Superior tomiuin with a conspicuous tooth, and inferior 



tomium with a corresponding notch. Superciliary process 

 of the lachrymal elongated, narrow, reaching nearly across 

 the orbit. Posterior margin of the sternum nearly even, 

 with a pair of large oval foramina. One or two outer pri- 

 maries with their inner webs emarginated near their tips. 



Group 1, Falcones. 



2. Tomia without tooth or notch.* 



Superciliary process of the lachrymal abbreviated, reaching 

 only half-way across the orbit. Posterior margin of the 

 sternum with a pair of deep indentations. Three or more 

 outer primaries with, their inner w^ebs sinuated near the 



middle portion Group 2, Polybori. 



1). Nostril a large opening without bony-riramed margin or central 

 tubercle. 



3. Superciliary process of the lachrymal elongated, broad, ex- 



tending nearly across the orbit. Tomia without tooth or 

 notch. Posterior margin of the sternum as in Falcones. 

 Four or more outer primaries with inner webs sinuated near 

 the middle portion Group 3, Micrastures. 



B. — Posterior toe elongated, almost equal to the lateral pair. Tarsi and 

 toes covered uniformly with thin, rough, imbricated scales. 



4. Tomia without tooth or notch. Nostril as in Falcones and 



JPolyhori. Superciliary process of the lachrymal elongated, 

 very broad, reaching nearly across the orbit. Posterior 

 margin of the sternum nearly even, entire, and without 

 foramina. Primaries as in Polybori and Micrastures. 



Group 4, Rerpetotheres. 

 Genera of Polybori. 



A. — Tarsus ^-| its length longer than the middle toe; outer toe but 



little longer than the inner; posterior toe very decidedly shorter 



than the inner. Inner webs of primaries deeply sinuated. Habits 



chiefly terrestrial. 



a. Nostril linear^ obliquely vertical, its tubercle concealed; anterior 



outline of the cere vertical and nearly straight. 



1. PoLYBORUS. — Nostril linear, obliquely vertical, its posterior 

 end the upper one ; situated in the upper anterior corner of 

 the cere. Occipital feathers elongated into a depressed crest. 



0. Nostril circular, in the middle of the cere, its tubercle exposed ; 

 anterior ontline of the cere doubly curved. 



2. Phalcobjenus. — Tooth and notch of the tomia of the bill 

 nearly obsolete ; lower jaw nearl^^ naked ; outer toe not ap- 

 preciably longer than the inner ; posterior toe reaching much 

 beyond the first joint of the middle toe ; claws remarkably 

 blunt, slightly curved ; posterior face of the tarsus without 

 distinct rows of quadrate scales ; upper tail-coverts remark- 

 ably developed, covering nearly two- thirds the tail ; size 

 large. 



* Though faint indications of these are observable in some genera (Milrar/o and 

 JPhalcobwnus) in the horny sheath, they cannot be detected in the bones of the bill. 



