BIRDS OF NORTH AND MIDDLE AMERICA 83 



toes." Adults with head, neck, and underparts (includmg underwing 

 coverts) immaculate white, upperparts mostly black, glossed with dark 

 bronzy purple or greenish. Young similar, but head and neck nar- 

 rowly streaked with dusky and black of upperparts less glossy. 



Range. — Southern United States to Bolivia and Argentina. 

 (Monotypic.) 



KEY TO THE SUBSPECIES OF ELANOIDES FORFICATUS 



a. Scapulars and interscapulars glossed with dark ivy green (Campeche, southern 



Mexico, south to Argentina) E. f. yetapa (p, 90) 



aa. Scapulars and interscapulars glossed with dark purplish black (east and 

 central Mexico, northward) E. f. forficatus (p. 83) 



ELANOIDES FORFICATUS FORFICATUS (Linnaeus) 



North American Swallow-tailed Kite 



Adult (sexes alike). — Tail very deeply forked, the lateral rectrices 

 more than twice as long as the central pair; wings long, narrow, 

 pointed; head, nape, neck, entire underparts, and a broad transverse 

 area on the lower back white; wings, tail, rump and lower back, and 

 broad intersc apular region of upper back slate to blackish slate with a 

 slate-gray bloom on the secondaries, greater upper wing coverts and 

 upper tail coverts; scapulars and interscapulars with blackish violet- 

 gray sheen, in some hghts showing some bronze-green, the inter- 

 scapulars hke the scapulars but with relatively more bronze-green and 

 less blackish violet-gray gloss; the median upper primary coverts and 



" Pterylographic characters.— "Inner branch of the jugular part [of ventral 

 pterylae] distinct but short; outer branch entirely free. Dorsal portion of the 

 spinal tract usually long." (Nitzsch.) Contour-feathers with aftershafts; one 

 pair of inguinal powder-down patches; lumbar tract present; remiges 23. 



Osteological characters. — Cranium very similar in contour and proportions to 

 that of Pandion, but presenting important modifications in minor details. Super- 

 ciliary process of the lachrymal distinct from the frontal, which is completely 

 ankylosed with the nasal; inner convoluted edge of the palatines scarcely pro- 

 duced downward; nasal septum completely ossified; pterygoid bone narrow, and 

 of a uniform width throughout its length. Sternum similar to that of Pandion, 

 having, like it, a pair of indentations on the posterior margin, and destitute of 

 foramina; the clavicle, coracoids, and scapula are also very similar. 



Anatomical characters. — "Palate flat with two longitudinal ridges; upper 

 mandible with a tuberculate median ridge, lower deeply concave; posterior 

 aperture of the nares oblongolinear, with the edges papillate. Tongue somewhat 

 decurved, emarginate, and finely papillate at the base, flat above, its tip narrow 

 and acutely emarginate. (Esophagus of nearly uniform width, being destitute of 

 crop, and thus resembling that of the owls; its walls extremely thin; stomach very 

 large, round, slightly compressed, its muscular coat very thin, and composed of a 

 single series of fasciculi. Intestine short and rather wide; pylorus with three 

 knobs, duodenum forming a loop in the usual manner; no ciEca; rectum short, with 

 a large globular dilatation." (Macgillivray.) 

 839094—50 7 



