614 BULLETIN 50, UNITED STATES NATIONAL MUSEUM 



on the outside only, forming "breeches," downy on inner side; inferior 

 tract simple as far as middle of neck, narrow, separated from the 

 spinal tract by lateral apteria, its two limbs likewise narrow, strongly 

 divergent and united to the axillary tract at the shoulders, but without 

 the inner branch which occurs in most other Accipitres, and descends 

 from the furcula into the bend of the neck, the exterior branch equal 

 in width to the main stem, present on pectoral muscles, the interspace 

 between these two limbs considerable (greater than usual), the exterior 

 hook at its upper apex which occurs in many other Accipitres also 

 wanting, the main stem closely approaching the crest of the sternum, 

 anteriorly and diverging posteriorly, the inferior space being thus 

 much broader on the ventral part, the two main stems curving toward 

 the anus and terminating close to it; down feathers white or gray, 

 remarkably soft, moldlike, clinging together when present, all with 

 main shaft and aftershaft of equal length, everywhere sparse, some- 

 times entirely wanting on some apteria, especially the lateral neck 

 spaces; contour feathers with a considerable but, as usual (in Accip- 

 itres) downy aftershaft, the main shaft rigid, the barbs, for the most 

 part, pennaceous. 



Nest usually in holes of trees or in recesses among rocks on cliffs. 

 Eggs several, short-ovate to oval, highly colored (more or less heavily 

 spotted with reddish brown on a whitish, buff, or light brown ground 

 color), their shells with reddish yellow translucence. 



Range. — Cosmopolitan in range. Only one genus (with several sub- 

 genera) in North and Middle America 



Genus FALCO Linnaeus 



Falco Linnaeus, Syst. Nat., ed. 10, i, 1758, 88. (Type by subsequent designation, 



Falco subbuteo Linnaeus (A. O. U. Committee, 1886).) 

 Hypotriorchis Boie, Isis, 1826, 970. (Type, by original designation, Falco subbuteo 



Linnaeus.) 

 Erythropus Brehm, Isis, 1828, col. 1270. (Type, by monotypy, Falco erythropus 



Linnaeus.) 

 Pannychistes Kaup, Skizz. Entw.-Gesch. Eur. Thienv., 1829, 57, 190. (Tj^pe, by 



original designation, Falco rufipes Beseke= Fa/co vesperlinus Linnaeus.) 

 Falcula Hodgson, Journ. Asiat. Soc. Bengal, vi, 1837, 365, footnote. (Type, not 



designated. "I exclude Tinnunculus etc., under the separate sub-generic 



title of Falcula.") 

 Dendrofalco Gray, List. Genera Birds, 1840, 3. (Type "Hypotriorchis Boie, 



Aesalon et Lanirius Briss . . .") 

 Dendrofalco Bonaparte, Icon. Faun. Ital., i, fasc. 29, 1840, te.xt to pi. 24. (New 



name for Hypotriorchis Boie.) 

 Tichornis Kaup, Mus. Senckenb., iii, Heft 3, 1845 (= 1844), 257. (Type, by original 



designation, Tinnunculus cenchris "Frisch." ■= Falco naumanni Fleischer.) 

 Poecilornis Kaup, Classif. Siiugeth. und Vogel, 1844, 108; also Mus. Senckenb., 



iii. Heft 3, 1845 (= 1844) 257. (Type, by monotypy, and original designation, 

 Falco sparverius Linnaeus.) 



