378 BULLETIN 50, UNITED STATES NATIONAL MUSEUM 



L. ghiesbreghti, its claw longer than the digit (except in L. semiplumbea 

 in which shorter); claws moderate in size and curvature, acute (not 

 very acute in L. princeps) distinctly graduated in size, that of outer 

 toe about two-thirds to nearly three-fourths as long as that of hallux. 



Plumage and coloration. — Plumage in general moderately full and 

 compact; loral region rather sparsely bristled (especially in L. princeps 

 and L. semiplumbea,''^ more densely so in L. lacernulata) ; feathers of 

 thigh short, not forming distinct "pantalettes," except in L. ghies- 

 breghti and L. princeps. Coloration very variable, but always a com- 

 bination of black and white, or black, gray, and white, the young 

 essentially like adults. 



Range. — Continental tropical America, from southern Mexico to 

 southeastern Brazil, Peru, and Ecuador. (About 8 species.) 



KEY TO THE NORTH AND MIDDLE AMERICAN FORMS OF LEUCOPTERNIS 

 a. Abdomen white abundantly and narrowly barred with blackish (Costa Rica 



to Panama) L. princeps princeps, ad. (p. 387) 



aa. Abdomen white or gray, but not barred with black. 

 b. Entire underparts gray. 



c. Thighs distinctly barred with white; abdomen slightly mottled with 



white (e. Panama to Ecuador) L. plumbea, young, (p. 386) 



cc. Thighs indistinctly barred with white; abdomen not mottled with 



white (e. Panama to Ecuador) L. plumbea ad. (p. 385) 



66. Underparts white. 



c. Top of head and entire upperparts deep slate gray: (Honduras to Ecuador) . 



d. Throat with black shaft Hues L. semiplumbea, young (p. 384) 



dd. Throat with no black shaft lines.. _L. semiplumbea, ad. (p. 383) 

 cc. Top of head and upperparts of body (except wings and tail) prac- 

 tically entirely white. 

 d. The greater upper wing coverts pure white (s. Mexico to Guatemala 

 and Brit. Honduras). 



Leucoptemis albicoUis ghiesbreghti, ad. (p. 381) 



dd. The greater upper wing coverts with some black, tipped with white. 



e. The dark areas on the inner primaries and the secondaries 



fuscous brownish, obscurely but definitely barred with blackish 



(Honduras to Panama). 



/. Crown and occiput with fine blackish or brownish streaks; 



lesser upper wing coverts much spotted with black and white. 



L. albicollis costaricensis, juv. (p. 380) 



ff. Crown and occiput unstreaked; lesser upper wing coverts with 



little or no black. 



g. Tertials or innermost secondaries barred or otherwise marked 



with blackish- _L. albicollis costaricensis, imm. (p. 380) 



gg. Tertials or innermost secondaries wholly white or very 



nearly so L. albicollis costaricensis, ad. (p. 379) 



ee. The dark areas on the inner primaries and secondaries slate 

 black to black, not barred with darker or very indefinitely 

 and faintly so. 

 /. Back of head with fine brownish-blackish lines; lesser upper 



^8 The orbital region is almost nude in L. princeps and L. plumbea. 



