112 
white or pale rusty.ground. Wing, 0.35-0.05; tail, 5.50-0.30; culmeu, 
0.35-0.40 ; tarsus, 1.85-2.05; middle toe, 1.05-1.25. 
Young female :* —Exactly like the young male in markings and colors. 
firin' H r 7K Q UA . /3rrA rr . _— a — n . * a — a o/i 
Wing, 
7.75-8.00; tail, 0.50-7.00; culmen, 0.45-0.50 ; tarsus, 2.05-2.30 
middle toe, 1.30-1.50. 
To represent the average style of the adult male, we select a speci¬ 
men from Pennsylvania, No. 59055, Nazareth ; L. E. Ricksecker. In 
this example, the upper parts are a uniform plumbeous throughout, 
the pileum being hardly appreciably darker than the back, and the tail 
equally blue with other portions; the tail has a distinct, narrow, white, 
terminal border; the longer upper tail-coverts also have very narrow 
white tips. On the lower parts (i. e ., breast, sides, flanks, and abdomen), 
the white and rufous bars are about equal in width, the latter growing 
wider toward the shaft of the feathers, along which they are connected 
by a narrow streak of rufous, the shaft itself being blackish ; the white 
bars being thus broken into transverse oblong spots. 
There are now before us thirty examples of the adult of this species, 
and we have examined many more; and our conclusion is that the va¬ 
riations exhibited in the plumage are purely individual, having nothing 
to do with climatic causes, since the two darkest examples are from 
Chiriqui, New Granada, and Fort Bridger, Wyoming, and the two light¬ 
est-colored ones are from G uatemala and Fort Resolution, Hudson’s Bay 
Territory, while others from the Atlantic States are not distinguishable 
from some obtained on the Pacific coast. As illustrating the extremes 
of variation in the adult plumage, we cite the following specimens :— 
The lightest in the entire series is an adult male from Ohoctun, Vera 
Paz, Guatemala (January), in the collection of Mr. Salvin. In this, the 
upper parts are a light, decidedly bluish, plumbeous, with conspicuous 
black shaft-streaks, exceedingly similar to the dorsal surface of adult 
males of Falco eolumbarius ; the pileum is decidedly darker, with the 
shaft-streaks less conspicuous, and the tail is decidedly more brownish 
than the upper coverts. There is a quite distinct narrow superciliary 
stripe of small white streaks. The general aspect of the lower parts is 
white, all the feathers except on the anal region and crissnm with very 
conspicuous blackish shaft-streaks, these being rendered the more 
prominent by the faintness of the rufous markings, which are distinct 
only along the sides, and even on the tibte are narrower than the white 
interspaces. A peculiar feature of this specimen, so far as the series 
before us is concerned, is that the dusky bands on the inner web of the 
primaries are broken into irregular cloudings, although they have a gen¬ 
eral tendency toward transverse bands. 
A specimen from Fort Resolution, Hudson’s Bay Territory, April 2G 
(No. C29, Mus. R. R.), is very similar, but the bars of the lower parts 
are better defined, although not deeper in color, and the upper parts 
are darker and more uniform plumbeous; the superciliary streaks are 
also concealed or nearly obsolete. In this specimen, as in many others, 
the rufous bars are bordered with a narrow, dark, slaty margin. 
The darkest examples are an adult male in Mr. Salvin’s collection 
(No. 3705) from the southern slope of the volcano of Chiriqui; one 
from Utah (Beaver, September, 24; No. 2130, Mus. R. B.); and one in 
the National Museum, from Fort Bridger, Wyoming (No. 10759, May 20). 
The two former are alike in their upper plumage, which is a very 
dark plumbeous, becoming gradualy but 
on the pileum, the shafts not conspicuously 
very perceptibly 
darker; the longer 
darker 
upper 
Iris sulphur-yellow : tarsi and toes rich lemon-yellow. (Fresh colors of No. 53*204.) 
