FALCONID^ — THE FALCOXS. 285 



little less pure white beneath, the lower parts being very appreciably tinged with rufous 

 posteriorly. 



Hab. Plains of the United States, from Minnesota to Texas (Devil's River, M. S. I.). 



Var. lucasanns, Kidgwat. 



ST. LUCAS EED TAIL. 



" Buieo bormlis var. htcasaniis, RiDow.iy," CouKs, Key, 1872, 21C (under .B. horcalis). 



Sp. Guar. Adult. General appearance of the normal plumage of var. calurvs, but the 

 upper parts more uniformly blackish, and the upper tail-coverts and tail uniform rufous, 

 the latter without a trace of a black bar. Beneath nearly uniform reddish ochraceous, or 

 light rufous, the usual abdominal belt merely indicated by a few inconspicuous spots ; no 

 trace of transverse bars on the lower parts Female ? (No. 16,925, Cape St. Luca.s Sept. 

 1.5, 18.59; J. Xantus). Wing. 16.00; tail. 9..50 ; tarsu.s, .3.00: middle toe, l.GO. Wing- 

 formula 5, 4, 3, 2 - 6 - 7 - 8 - 9, 1, 10. 



Young. Not distinguishable, by positive characters, from that of var. calurus. 



Hab. Peninsula of Lower California. 



All adult specimens from the peninsula of Lower California agree with 

 that described above, in the peculiar features which I consider as character- 

 izing a well-marked local race. The present form is most nearly related, in 

 its adult dress, to the var. h-ideri of the plains, in its unbarred tail and im- 

 maculate lower plumage, but differs from this, in having the upper parts 

 nearly black instead of almost white, tlie upper tail-coverts deep rufous, like 

 the tail, instead of white, and the lower parts rufous instead of white ; in 

 the rufous lower plumage and very dark upper parts, it closely resembles 

 var. costaricensis^ of Central America and Southern Mexico, but the latter has 



1 Butco borealis, var. costarkensis, Ridgway. Biitco borcalis (all citations from Central 

 America). 



Sp. Char. Adult (No. 30,409, Costa Eica ; Dr. A. von Frantzius). Head, neck, and upper 

 parts continuous, unvariegated brownish-black ; whole throat white, with a few cuneate spots 

 of black ; black of the neck meeting narrowly across the jugulum ; pectoral area immaculate pure 

 white ; upper part of abdomen with an imperfect belt of distinct narrow lanceolate strips of black ; 

 whole posterior lower jiarts fine pinkish ochraceous, unvariegated ; tibiae deepest, inclining to 

 delicate ochraceous-nifous ; upper tail-coverts innnaculate rufous. Tail as in var. borealis. Wing, 

 16.00; tail, 9.00; tarsus, 3,20; middle toe, 1.80. Bill very high, abruptly curved. Wing- 

 formula, 4, .5, 3, 6, 2 ; first, shoi'test. 



This veiT curious variety is tliat which departs furthest from the tine borcalis ; not only the 

 details, but in a measure the pattern, of coloration, being greatly modified. The perfectly con- 

 tinuous pure brownish-black of the whole head and neck, sharply contrasted with the white throat- 

 patch, are features which distinguish it from every other variety of this group ; while the deep 

 rufous tibiae, and almost utter absence of transverse bars beneath, are also very distinctive char- 

 acters. 



The .second of the two Costa Rican specimens before me (No. 33, .507 ; J. Canniol) differs from 

 the type in havine the white of the peetoral area clouded by an encroachment of the blackish of 

 the neck ; and acrcss the abdomen is a deep wash of the same. The tail-feathers exhibit indica- 

 tions of spots along the shafts, as in var. calurus; while the upper tail-coverts have a very few 

 bars of blackish. 



Yoiing (37,338, Tres Marias Islands, January ; Col. A. .1. Grayson). Similar to the adult 



