114 BULLETIN 5 0, UNITED STATES NATIONAL MUSEUM 



the lores sparsely feathered; tarsus short, not or slightly longer than 

 the middle toe; tarsus scutellate; plumage soft. 



The Milvinae is the least well marked of all the subfamilies of 

 Accipitridae, but it forms a natural group in itself and, by its segre- 

 gation, permits a clearer definition of the groups most closely allied 

 to it, the Perninae and the Accipitrinae. Besides the three genera 

 found in North and Middle America it contains one other genus in 

 South America and four more in the Old World. 



Genus HARPAGUS Vigors 



Harpagiis Vigors, Zool. Journ., i, No. 3, Oct. 1824, 327, 338. (Type, by original 



designation, Falco diodon Temminck.) 

 Bidens Spix, Avium Species Novae (Av. Bras.), i, "1824" [1825-1826?], 14. (Type 



by subsequent designation (Stephens, in Shaw's Genl. Zool., xiv, pt. 1, 1826, 



346) Falco bidentatus Latham.) 

 Diodon (not of Linnaeus, 1758) Lesson, Traits d'Orn., ii, 1830, 95. (Type, by 



original designation, D. brasiliensis Lesson ==faZco bidentatus Latham.) 

 Diplodon Nitzsch, Pterylographia, 1840, 93. (Type, by original description, 



Falco bidentatus Latham.) 



Rather small Accipitridae (wing about 203-232 mm.) with maxil- 

 lary tomium doubly toothed, mandibular tomium truncate at tip and 

 notched subterminallj^; longest primary exceeding distal secondary 

 by less than length of tail, the latter two-thirds or more as long as 

 wing, its tip more or less rounded ; tarsus one-fifth or more as long as 

 wing, the planta tarsi without transverse scutella, and with plumage 

 soft and blended. 



Bill relatively short but very stout, its depth at frontal antiae 

 decidedly less than chord of culmen and decidedly more than its width 

 at same point; culmen about as long as first two phalanges of middle 

 toe, distinctly (though sometimes rather broadly) ridged, strongly 

 and regularly curved from base, the tip of maxilla forming a moder- 

 ately long and rather thick unguis; gonys half as long as culmen or 

 slightly more, strongly convex, ascending terminally, sometimes rather 

 prominent basally, where projecting into median portion of inter- 

 ramal area;^^ maxillary tomium much produced, its margin divided 

 by two distinct notches, separating two distinct toothlike projections, 

 the posterior portion concavely incised; tip of mandible obliquely 

 truncate, preceded by a deep concave notch separating two prominent 

 angular tomial projections; cere relatively narrow, its lateral anterior 

 outline slightly convex above, receding and slightly concave below; 

 nostril small, longitudinally elliptical or subcrescentic, situated about 

 midway between commissure and top of cere, and near anterior edge 

 of cere. Wing moderately long, rather rounded, the longest primary 

 exceeding distal secondary by about one-third the length of tail, or 



*8 A unique character, at least among American Accipitridae. 



