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Genus LEUCOPTERNIS, Kaup. 
Dccdalion Vigors, 1824 (not of Savigny, 1809). [Fkle G. R. Gray.] 
Leucopternis Kaup, Isis, 1847, 210. Type, Falco melanops Temminck. 
Pseudastur Blyth, Cat. Birds Mus. Asiat. Soc. Bengal, 1849, 24. Type, Falco lacernu 
latus Temm. 
—Similar to Urubitinga , but tarsus not more than twice as long 
as the middle toe; inner webs of only four or five outer primaries 
cut (the cutting being a distinct emargination); and nostril more nearly 
circular, and rather vertical than horizontal. 
This genus is most similar to TJrubitinga , but presents the above well- 
marked differences, with the addition of another and equally important 
one, viz, the similarity of the young and adult stages in plumage. The 
colors, too, are chiefly or largely white, instead of mainly black. There 
is also a very close relationship to Asturina , but in the latter the old 
and young stages of plumage are exceedingly dissimilar, the nostril is 
very decidedly horizontal, and the emarginations of the primaries end 
abruptly with the fourth, on which it is very distinct. The genus 
Rupornis , next in order of relationship, is still more remotely allied. 
The sternum of L. semiplumbeus most resembles that of Asturina 
plagiata (it has not been compared with that of A. nitida ), from which it 
differs mainly in smaller size. That of Rupornis (rujicauda ) differs con¬ 
spicuously in much greater posterior breadth and larger foramina, 
which in the other two are sometimes nearly or quite obsolete, and 
always small. 
LEUCOPTERNIS GHIESBRECHTI. 
Buieo ghiesbrechti Dubus, Esq. Orn. 1843, pi. 1.— Gray, Gen. fol. sp. 18.— Strickl. Orn. 
Syn. i, 1855, 36.— Scl. P. Z. S. 1857, 227 (Southern Mexico).— Scl. & Salv. Ibis, 
1S59, 217.— Lawr. Ann. N. Y. Lyc. vii, 1861, 289.— Salv. P. Z. S. 1867, 158 
(Veragua).— Gray, Hand List, i, 1869, 8.— Sumiciirast, Mem. Bost. Soc. N. H. 
i, 1869, 560 (Vera Cruz, hot reg.). 
Leucopternis ghiesbreghti Bonap. R. Z. 1850, 481; Consp. 19 .—Scl. & Salv. Ex. Orn. 
1868, 121; Norn. Neot. 1873,119 .—Salv. P. Z. S. 1870, 250 ; Ibis, 1872, 242. 
Tachytriorchis ghiesbrechti Bon. C. R. xli, 1855, 651. 
Asturina ghiesbrechti Sciil. Mus. P.-B. Asturinw , 1862, 11. 
Urubitinga ghiesbrechti Sharpe, Cat. Acc. B. M. 1874, 217. 
Hub .—Middle America, from Panama to Mirador. 
Wing, 12.00-15.25; tail, 8.50-9.50; culmen, 1.05; tarsus, 2.80-3.65; 
middle-toe, 1.50-1.70. Fourth or fifth quills longest; first shorter than 
seventh, sometimes shortest. Almost entirely pure white; a broad 
zone across the tail near its end, and a portion of the primaries, prim¬ 
ary-coverts, and alulte deep black. Adult: —Basal half or more of the 
primaries white; no bars on the wing. Young: —Primaries black 
nearly to the base, or else the white portion barred with black: wing- 
coverts more or less barred with black on the lower feathers. Loral 
bristles and streak behind the eye black. In the youngest specimens, 
the black portion of the primaries barred with paler. 
