68 BULLETIN 5 0, UNITED STATES NATIONAL MUSEUM 



<Polihieracinae Peters, Check-list Birds of World, i, 1931, 281 (includes 

 Gnmpsonyx). 



This subfamily is represented in North and Middle America by 

 two genera, Elanus and Gampsonyx. The subfamily is characterized 

 by having a schizognathous type of palate; the lachrymal with a double 

 superciliary plate; coracoids not overlapping at sternum; upper portion 

 of anterior face of tarsometatarsus with no bony ring; outer (fourth) 

 toe not reversible; claws graduated in size from that of the hallux 

 (largest) to that of the outer (fourth) toe (smallest), not contracted 

 to theu- under surface, but smoothly flattened or even rounded; deep 

 plantar tendons of type III; tendons of biceps not split; tensores 

 patagii not peculiar; cervical vertebrae 13 or 14; caeca minute; not 

 more than two (sometimes none) of outer primaries with inner web 

 sinuated; tarsus and basal portion of toes covered uniformly with 

 very small roundish or hexagonal scales, only the terminal portion of 

 the toes having transverse scutella; outer toe somewhat shorter than 

 the inner toe; nostril broadly ovate, nearly horizontal, situated near 

 middle of cere. 



It contains, besides Elanus and Gampsonyx, two other genera, 

 Machaerhamphus ^'' and Chelictinia.^^ The former has the culmen 

 exceedingly compressed, forming a distinct vertical ridge, and the 

 tarsus exceeding the length of the middle toe without the claw by 

 at least 10 mm. Chelictinia is like Elanus in not having the culmen 

 compressed and in having the tarsus less than 10 mm. longer than 

 the middle toe, but it has the tail deeply emarginate. 



Chelictinia is a monotypic genus, confined to Africa. As the single 

 species {O. riocouri) is a rare bird in collections, a full diagnosis of the 

 genus may not be out of place here. 



Bill much as in Ictinia, but less robust; nostril unusually large, 

 oval, obliquely vertical; cere very narrow and compressed on top; 

 tarsus considerably longer than middle toe (without claw); web 

 between outer and middle toes just appreciable; tarsus and toes 



37 Mochaerhamphvs Westerman, Bijdr. tot de Dierk., i, 1848, 29, pi. 12 (type, 

 by monotypy, Machaerhamphus alcinus Westerman). A highly peculiar genus 

 of crepuscular, bat-eating hawks found in Africa, Madagascar, southeastern 

 Asia to New Guinea. Cf. Stuart Baker, Fauna Brit. India, Birds, ed. 2, v, 1928, 

 169-170; Bannerman, Birds Trop. West Africa, i, 1930, 233-235; Chapin, Bull, 

 Amer. Mus. Nat. Hist., Ixv, 1932, 545. 



38 Chelictinia Lesson, ficho du Monde Savant, x, 1843, col. 63 (type by mono- 

 typy, Elanoides riocmirii Vieillot) ; Nauclerus Vigors, Zool. Journ. ii, 1825, 386 

 (type, as designated by Stephens, 1826, Falco riocour "Vieill." Temminck). — 

 Chdidopteryx Kaup, Classif. Saugeth. und Vogel, 1844, 112 (type, by monotypy, 

 Elanoides riocouri Vieillot). — Cypselopteryx Kaup, Archiv fiir Naturg. 1850, i, 31 

 (new name for Chdidopteryx Kaup). — Elanopterus Antinori, Cat. Descr. Coll. 

 Ucc. Africa, 1864, xi (lapsus for either Chelidopteryx or Cypselopteryx; used for 

 Chelictinia riocouri) . 



