28 Allen on an Inadequate “Theory of Birds' Nests." 
color among our native birds being rarely greater than in these 
species. The subpensile nests of some of the Vireos are to be per- 
haps more properly referred to the type of open nests. In either 
case we find only slight sexual difference in color, with the olivaceous 
hue of the back well fitted for concealing the female bird. But this 
is in part offset by the usually light color and somewhat exposed 
situation of the nest. 
4. The great bulk of the species fall of course into the fourth 
category, or those with the nest open. These embrace (with two 
exceptions, the Woodpeckers and the Kingfishers) birds of every 
family represented in our fauna, and are about equally divided be- 
tween ground-builders and those which nest in bushes or trees. As 
a rule (as, in fact, throughout the class of birds) in those arrayed in 
conspicuous tints the females are obscurely colored, in comparison 
with the males. Yet to this rule there are exceptions, as notably 
among the Jays, some of which do have “ surprisingly gay and con- 
spicuous colors,” and among which both sexes are equally brilliant. 
The shining black color of the Crows, the Raven, and some of the 
Blackbirds are equally or (in the latter) almost equally shared by 
both sexes, while the color is by no means well adapted to conceal- 
ment. In many species the males, even when brightly colored, 
share with the females the duties of incubation. This is the case 
with the Rose-breasted Grosbeak, in which the male is most con- 
spicuously colored, and who not only shares the labor of incubation, 
but has the most injudicious habit of indulging in loud song while 
sitting on the nest. In many of our ground-nesting Sparrows the 
sexes, in respect to coloration, are wholly indistinguishable ; their 
obscure colors, arranged generally in streaks and spots, are cer- 
tainly in the highest degree protective ; their nests, although not 
domed, or even “covered,” in the strict sense of the term, are gen- 
erally most effectually concealed under tufts of herbage, and are 
hence far better shielded from observation than the pensile, domed, 
or bulky, covered nests that are regarded by our author as so highly 
conducive to security through the concealment of the eggs and 
young or the sitting female. 
Among the groups instanced by Mr. Wallace as building open 
nests are “ the extensive families of the Warblers ( Sylviadce ), 
Thrushes ( Turdidce ), Flycatchers ( Muscicapidce ), and Shrikes {La- 
niadce ).” While in a considerable proportion of the species of 
these groups the males are “ beautifully marked with gay and con- 
