178 
middle toe, 1.25-1.35. Inner webs of only four outer primaries dis- 
metly emarginated; third to fifth quills longest; first shortest. Tail 
neaily even, the lateral pair of feathers slightly the shortest. Adult :— 
ui ne upper surface, including the side of the head and neck, uniform 
aariv plumbeous. Tail black, crossed at a little beyond the middle by a 
narrow, continuous band of whte, and sometimes with a second, less 
continuous, band, nearer the base. Entire lower parts, including the 
c im and throat and lining of the wiug, continuous pure white, the sides 
i P 16 ai1 ^ sometimes the throat, with a few fine shaft-streaks of 
ausky. Inner webs of the primaries ashy, barred with dusky beyond 
t eir situations. Bill slate-black, the basal two-thirds of the lower 
mandible and that portion of the upper below the cere pale yellow ; 
cere, rictus, and base of lower mandible bright orange-red; tarsi and 
toes deep reddish-orange; claws black. 
-The variations in the plumage of this species consist mainly in the 
presence or absence, and amount when present, of plumbeous wash on 
at i 6 aU( l ^e streaks of the same on the throat. In 
t ^ ,e ou ^ er side ot the tibiae is almost wholly plumbeous, while 
in JNo. ho334 it is entirely absent; in the former, each feather of the 
throat has a distinct dusky shaft-streak, while in the latter the throat is 
immaculate. Other specimens are variously intermediate between these 
extremes. 
*0.66334 differs from all others examined in having two bands on 
the tail, instead of only one; these are both well defined, though the 
anterior one is not, like the posterior one, continuous. No other differ¬ 
ences, however, can be detected, while in other specimens this second 
»and is found indicated by transverse white spots on the inner webs. 
List of specimens in United Slates National Museum. 
Catalogue No. 
Original No. 
Sex and age. 
Locality. 
When col¬ 
lected. 
47364 
d ad. 
Costa Rica. 
64941 
562 
— ad. 
.do. 
64942 
160 
d ad. 
.do. 
• | loin 
64943 
552 
? ad. 
.do. 
, 10 4 O 
66334 
— ad. 
.do. 
, lofo 
66335 
35 
— ad. 
Costa Rica (Old Harbor). 
- - , lo 4 0 
67860 
265 
d ad. 
Costa Rica (Talamanca). 
67863 
— ad. 
.do. 
67864 
205 
? ad. 
.do. 
From whom received. 
J. Carmiol. 
Prof. Wm. M. Gabb. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Other specimens examind .—la 
(Costa Rica); total, 13. 
mus. G. N. Lawrence, 3 (Panama); R. Ridgway, 1 
LEUOOPTERNIS PRINCEPS. 
Leucoptcrnis princeps Scl. & Salv. P. Z. S. 1865, 429, pi. xxiv; Ex. Orn 1868 
Nomen cl. Neot. 1873, 119.— Lawk. Ann. Lyc. N. Y. ix, 1868 133— Saiv 
1872, 241-243. ’ ' * ' 
Buteo princeps Gray, Hand List, i, 1869, 9. 
Urubitinga princeps Sharpe, Cat. Acc. Brit. Mus. 1874, 220. 
122 ; 
Ibis, 
Ilab .—Costa Rica (mountainous districts). 
Wing, 14.00-15.20; tail, 7.50-9.00; tarsus, 3.25-3.80; middle toe, 2.90. 
Fourth quilMongest, the fifth scarcely shorter; first 3.50 shorter than the 
