32 
Goss on Breeding of the Buck, Hawk. 
theory of evolution by means of what has been termed “natural 
selection ” and “ sexual selection ” have been betrayed. 
In conclusion, I desire to call attention to an interesting coinci- 
dence between the manner of nesting among birds and the color of 
the eggs, and one so striking that it is almost surprising that some 
ingenious theorist has not seized upon it as a basis for a “ theory of 
birds’ nests,” either independently or as a modification of that pro- 
posed by Mr. Wallace. It curiously happens that nearly all birds 
that nest in holes, either in the ground or in trees, lay white eggs, 
embracing, for instance, all the Woodpeckers, Kingfishers, Bee-eat- 
ers, Rollers, Hornbills, Barbets, Puff-Birds, Trogons, Toucans, Par- 
rots, Paroquets, and Swifts, while only occasionally are the eggs 
white in species which build an open nest. In only two or three 
groups of land birds, co-ordinate with those just named, that build 
an open nest, are the eggs white, namely, the Owls, Humming-Birds, 
and Pigeons. On the other hand, in only two or three small groups 
of species that nidificate in holes are the eggs speckled or in any 
way colored. There is, in fact, a closer relationship, or rather a 
more uniform correlation, between the color of the eggs and the 
manner of nesting than between the color of the female parent and 
the concealment or exposure of the nest. There are, however, here 
apparently too many exceptions to bring this coincidence into the 
relation of cause and effect. It is perhaps rather comparable with 
the pattern of coloration that so often, to a greater or less degree, 
marks nearly all the species of a whole natural family, and often 
prevails throughout large genera, for which the conditions of envi- 
ronment offer no explanation, since it as often occurs in cosmopoli- 
tan groups as in those of local distribution, and which, in the pres- 
ent state of our knowledge, seems wholly inexplicable. 
BREEDING OF THE DUCK HAWK IN TREES. 
* BY N. S. Goss. 
As the Falco communis var. anatum is supposed to nest almost 
exclusively on high rocky cliffs, and rarely if ever in other situa- 
tions, I think it will be of interest for me to say that I found 
in February, 1875, a pair nesting about three miles southeast of 
Neosho Falls, Kansas, in the timber on the banks of the Neosho 
