JAMES NE WTON BASKE TT. 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 {Zenaidiira macrurd) 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 {Sialia 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. 



