120 
NISUS VENTRAL IS. 
Accipiter crythrocncmius ? Scl. P. Z. S. 1855, 134.— Orton, Am. Nat. 1871, 624 (Quito 
Valley). 
Accipiter ventralis Scl. P. Z. S. 1866, 3'03. —Scl. & Salv. Ex. Orn. ii, 1867, 25, pi. xiii ; 
ib. xi, 170 ; P. Z. S. 1870, 782, 788 (Venezuela); Norn. Neotr. 1873, 120.— Gray, 
Hand List, i, 1869, 32.— Sharpe. Cat. Acc. B. M. 1874. 149. 
f Accqnter nigrc-plumbetis; Lawr. Ann. N. Y. Lyc. 1869, 270 (Quito Valley, Ecuador— 
melanism ?). 
Bab. —Venezuela, Colombia, and Ecuador. 
Wing, 6.30-8.70; tail, 5.40-7.25; culmen, 0 35-0.55; tarsus, 1.65- 
2.20; middle toe, 1.10-1.50. Fourth and fifth quills longest; first 
shortest; outer five with inner webs sinuated. Tail even, or very 
slightly rounded. Tibiae uniform deep rufous. Tail dull black, crossed 
by four narrow continuous bands of slate-gray or brownish gray, and 
narrowly tipped with grayish or white. Adult. —Above, uniform dark 
plumbeous except the tail, the scapulars and upper tail-coverts with 
concealed white spots. Beneath, chiefly rufous, sometimes entirely so, 
but usually whitish in the crissum and throat, and often broken along 
the middle line by an indistinct transverse white spotting. Young .— 
Above, dark sepia, the feathers with rusty terminal borders. Lower 
parts (except tibiae) white, marked with large, rather longitudinal, sag¬ 
ittate spots of umber. 
Sexes alike in color, but differing in size as follows :— 
Males: —Wing, 6.60-0.65; tail, 5.70-6.20; culmen, 0.40-0.45; tarsus, 
1.90-2.10 ; middle toe, 1.25-1.30. (Six specimens.) 
Females: —Wing, 7.75-8.00; tail, 6.80-7.00; culmen, 0.50-0.55; tar¬ 
sus, 2.15-2.20 ; middle toe, 1.40-1.50. (Four specimens.) 
There is greater variation in the plumage of this species than in any 
of its allies, and, contrary to the usual rule, the adults vary more than 
the young. The darkest example of the latter we have seen is an adult 
male from Ecuador in Mr. Salvin’s collection. In this specimen, every 
portion of the lower parts is rufous, even the throat, crissum, and lining 
of the wing being of this color, while the tibiae and abdomen are so 
dark and purplish as to border on a chestnut shade. The flanks show 
narrow, transverse, indistinctly-defined bars of white. An adult male 
from the interior of New Granada is quite a contrast to this, and rep¬ 
resents the light extreme. In this example, the breast is nearly uniform 
light gray and rufous, the former predominating, while the sides, 
abdomen, and flanks are barred with white, gray, and rufous, in broad, 
ragged, not well-defined bars, of which the white ones average the 
widest, while the rufous and gray are mixed in nearly equal proportion. 
The crissum and throat are pure white, the latter with dusky shaft- 
streaks; the lateral feathers of the former with a faint mottling of 
grayish. An adult male from Venezuela (Merida) has the flanks 
uniform deep rufous, like the tibiae; the breast, belly, and sides being 
light grayish-fulvous, becoming lighter toward tliejugulum; the feathers 
marked with darker grayish bars concealed beneath the surface. Other 
specimens are variously intermediate between these, there being usually 
more or less of an indistinct barring of white and grayish along the 
median line of the abdomen and breast. The young birds vary con¬ 
siderably also, especially in the markings of the lower parts. In the 
males, these are usually longitudinal on the breast; but in the two 
females before us, each of these markings spreads anteriorly, so as to 
form a spot of a widely sagittate form. 
Besides the variations noted above, the N. nigroplumbens (Lawrence) 
may represent a melanism of the adult plumage iu this species, since, 
