94 BULLETIN 5 0, UNITED STATES NATIONAL MUSEUM 



the upper portion feathered for from one-third to more than half its 

 length (except behind), the iinfeathered portion covered with rather 

 hexagonal scales, these smaller on lower portion of acrotarsium; middle 

 toe about as long as tarsus, or slightly shorter, the outer toe longer 

 than the inner, reaching (without claw) to about the antepenultimate 

 phalanx of middle toe; hallux about as long as outer toe or slightly- 

 shorter; toes, like tarsus, robust, their upper surface with a continuous 

 row of large, transverse scutella; claws moderate in size and curvature, 

 moderately acute, very broad, slightly hollowed beneath, their edges 

 sharp and prominent. 



P^umaye and coloration. — Plumage in general soft and full, the 

 feathers of pileum and nape sublanceolate, rather elongated, especially 

 on nape, those of underparts blended, normal (not broad and subtrun- 

 cate, as in Chondrohierax) ; secondaries large, the longest proximal ones 

 reaching nearly to tips of longest primaries; third to fifth primary 

 longest, the first shorter than seventh, sometimes shorter than ninth; 

 inner webs of outer four to six primaries shallowly sinuated; loral 

 region unfeathered but uniformly covered with short bristles, these 

 larger and antrorse along anterior margin; eyelids with small lashes. 

 Adults dark bluish gray above, the head and neck paler bluish gray, 

 fading into white on throat; underparts plain white; tail black, tipped 

 with white and crossed by three bands of bluish gray. Young with 

 head and neck whitish, the pileum more or less spotted with blackish 

 broAvn, upperparts dusky brown, tail bro\Miish gray to brownish 

 white, crossed by three bands of black, underparts plain white. 

 (There is a dark phase, in which the young have the underparts 

 striped with blackish and the head and neck, except throat, uniform 

 blackish.) 



Range. — Continental Tropical America. (One species within the 

 range of this paper.) 



Although by many authorities merged with Chondrohierax, Odon- 

 triorchis seems more nearly related to the African genus Aviceda; " 

 in fact, there is little difference between Odontriorchis and Aiiceda 

 beyond the relatively longer primaries and more rounded tail of the 

 former. 



KEY TO THE SPECIES OF LEPTODON 



a. Tail with a very broad ashy white median band (about 70-80 mm. wide) 

 and broadly tipped with ashy white L. forbesi (extrahmital «8) 



" Aviceda Swainson, Classif. Birds, i, 1836, 300 (diagnosis; no included species). 

 Type, by subsequent designation, Aviceda cuculoides Swainson. 



58 Odontriorchis forbesi Swann, Synop. Accip., ed. 2, 1922, 159 (Pernambuco, 

 Brazil). According to Hellmayr (Publ. Field Mus. Nat. Hist., zool. ser., xii, 

 1929, 456-457) the unique type of forhcsi is merely an aberrant pallialus and 

 forbesi is not a valid form. Cf. Peters, Check-list Birds of World, i, 1931, 199, 

 for further discussion. 



