JAMES NEWTON BASKETT. 99 
the Vulture branch of the family ; but now that they nest so 
largely in trees and protect their eggs so vigorously, there is 
a strong tendency in them all to lose their markings. 
In the cases of such small birds as lay white eggs in 
elevated exposed nests, many of them have quite probably 
been builders of concealed nests, or else their nests as now 
situated (as suggested by Mr. Wallace) are less exposed than 
may casually appear. Some have so recently taken to trees 
and the consequent exposure as not to have had time to 
develop a colored or protected egg. Others, perhaps, are so 
secure now on account of some other circumstances, that the 
tendency to reversion comes strongly in. For instance it is 
evident, from the broken-wing hypocrisy act, that our com- 
mon Dove (Zenaidura macrura) was primarily a ground- 
builder; and I may note here that while it used trees mostly, 
thirty years ago in my region, it is now chiefly nesting on the 
ground in oats, stubbles, and under weeds, and sometimes 
under tufts in pastures, thus showing a tendency to conceal 
the nest. It is said to build in trees exclusively in Jamaica 
since the introduction of the mongoose, though formerly a 
ground-builder there. There is much to show that our com- 
mon Bluebird (Siaia sialis) has only recently become a 
hole-builder, but its occasional white egg hints, in keeping 
with the habit, at a reversionary tendency that may one day 
make its egg unique among the clan of Thrushes, the eggs of 
which are now so constant in their coloration. I have here 
to record, however, that a nest of this bird has been recently 
found by a trustworthy naturalist, Professor Kilpatrick, of 
Central College, Mo., in a standing clump of weeds, with 
whose foliage of course the bluish-green egg well accorded. 
The bird may yet preserve its colored egg by a reversion to 
its primitive nesting habit. 
I have spoken much of the tendency to reversion in eggs. 
I am inclined to regard these reversions largely as ancient 
rather than modern, though some instances of recent rever- 
sions will be mentioned later. Nest location and structure, 
