BIRDS OF NORTH AND MIDDLE AMERICA 559 



to sixth (from outside) longest. Tail long and much rounded (nearly 

 as long as to longer than wing) . Tarsus long and rather slender, more 

 than twice as long as middle toe without claw, without transverse 

 scutella either before or behind (if with large scutella on acrotarsium 

 or planta tarsi, or on both, the scutella longer longitudinally than 

 transversely and arranged in double series). 



Although resembling the buteonine genus Accipiter m aspect and, 

 to a great extent, in habits, the Micrasturinae are essentially falcons 

 structurally, possessing, as they do, all the characters common to the 

 superfamily Falcones. They agree with the Falconinae and Herpeto- 

 therinae in the much elongated superciliary process of the lachrymal 

 (broader than in the former, narrower than in the latter) ; with the 

 Falconinae in the character of the posterior end of the sternum (nearly 

 truncate, with two oval foramina), and with both Falconinae and 

 Herpetotherinae, together with the Polyborinae in the produced 

 scapular process of the coracoids, the almost completely ossified nasal 

 bones, the strongly ridged inferior surface of the supermaxillary, and 

 in other osteological characters, in all of which the Micrasturinae 

 differ strongly from the Accipitrinae and the Buteoninae. 



In addition to the "facial ruff," which recalls that of Circus and the 

 Striges, the Micrasturinae further resemble the latter in the enlarged 

 ear aperture (of oval form and vertical position), dense, antrorse 

 hairlike bristles which cover and nearly conceal the cere, the soft, 

 downy character of the inner webs of the remiges, and the dichro- 

 matic character of some species, which exhibit a rufescent or erythris- 

 tic phase of plumage. It is probable that these resemblances are 

 purely adaptive, being connected in some way with their habits. 



Nitzsch describes the pterylosis of the Micrasturinae as having the 

 lumbar tract absent; dorsal portion of spinal tract in the form of an 

 elongated ellipse, but contracted into a band immediately in front of 

 the oil gland (but even there still broad), consisting exclusively of 

 scattered feathers, which become stronger posteriorly. The eyelids 

 are said to be without distinct lashes. 



This family contains a single genus with four species, restricted to 

 tropical continental America. 



Genus MICRASTUR Gray 



Brachypterus (not of Kugel, 1794) Lesson, Complement des Oeuvres de Buflfon, 



vii, 1836, 113. (Type, by original designation, Falco brachypterus Tem- 



minck.) 

 Brachypternus (emendation) Bonaparte, Rev. Mag. Zool., s^r. 2, ii, 1850, 489. 

 Brachypteryx (emendation) Bonaparte, Consp. Gen. Av., i, 1850, 30. 

 Carnifex (not of Sundevall, 1836) Lesson, ficho du Monde Savant, ser. 2, vi, 1842, 



1084. (Type, by monotypy, C. naso Lesson = Falco brachypterus Tem- 



minck = (Sporvitts melanoleucus Vieillot.) 

 Carnifer (emendation) Grat, Gen. Birds, i, 1849, 28. 



