124 



NORTH AMERICAN BIRDS. 



Juv. {$, 32,207, South Fork of the Platte River, July 19, 1838; C. S. McCarthy). 

 Above darker umber than the last, each feather distinctly bordered terminally with rusty- 

 ochraceous. Beneath with a deeper cream-colored tinge, streaks blacker; flank-patch 

 more conspicuous and uniform ; axillars unvariegated dusky. Wing-formula, 2, 3 - 1 = 4» 

 Wing, 13.25 ; tail, 7.25. 



Hab. Western division of North America, eastward to Illinois ; Oregon to Lower 

 California, and Texas. Localities : Texas, San Antonio and Eagle Pass (Dresser) ; 

 Arizona (Coues). 



The different stages of plumage are in this by no means so well defined 

 as in other species, there being nearly the same general appearance in all. 

 There is, also, very little variation in different specimens of the same age. 

 No. 8,504, ( 9 , Dalles, Oregon ; Dr. George Suckley) has the black markings 

 on the sides of the breast more circular, and the vandyke-black of the 

 axillars with a few circular white spots on the edges of the feathers. Wing, 

 14.50 ; tail, 8.40. Nos. 17,204 ( 9 , San Jose, Lower California ; Jolm Xantus, 

 January, 1860) and 18,258 {S ? Fort Buchanan, K M.) have the upper 

 surface almost perfectly continuous grayish-drab, the first absolutely un- 

 variegated by markings, though the feathers fade a little on edges. Beneath, 

 the white is very pure ; tlie streaks are numerous, sharply defined and 

 longitudinal Wing, 13.25 ; tail, 7.50 (17,204). 



The American Lanner Falcon is so very closely related to the Lanners of 

 Europe and Asia (var. lanariiis and var. jugger) that it is very difficult to 



indicate the differences which 

 separate them. The two Old 

 World forms above named are 

 more unlike each other than 

 they are from the two Ameri- 

 can races ; the var. jugger differ- 

 ing from mexicanus apparently 

 only in larger size ; and the var. 

 lanarius, more like polyagrus 

 than it is like either jugger or 

 mexicanus, differs from poly- 

 agrvs mainly in the greater 

 amount of white on the plu- 

 mage, this imparting a lighter 

 aspect to the pileum, and caus- 

 ing a greater development of 

 the light spots on tlie outer 

 webs of the primaries and 

 rectrices. 



Fako poiyagrus. The var. jJohjctgrus, compared 



with var. lanarius, is much 

 darker, having, at all ages, the crown uniformly brown, with darker streaks, 

 instead of having these streaks upon a white ground. The " mustache " is 



