96 
JV£STS AND EGGS OF 
as they have been by subsequent observations, and seek an explanation 
thereof which will be both rational and philosophic. 
In exposed situations, the eggs are subject to certain perils, such as 
exposures to storms and violent gusts of wind, which more retired places 
would guard against. The Auks have doubtless learned this as a lesson of 
experience. Perhaps, necessity only compels them to occupy such sites, 
when there is a scarcity of deep fissures and horizontal caverns, by reason 
of a su]3erabundance of mated individuals. If one egg could be better 
protected and covered than two, which the nearly erect attitude of the 
bird would seem to warrant us in believing, some females would cer- 
tainly not be slow in perceiving the advantages to be acquired. The 
experiment being tried by birds of unusual sagacity, and with happy 
results, in course of time all the others would be led to the practice of 
depositing a single egg. Furthermore, the laying of one egg, in case of 
breakage, would not be as severely felt as in cases where more than one 
constituted the complement. The habit of laying one egg in exposed 
situations, would doubtless be. continued for a while at least, should the 
species so accustomed, ever be called upon to nest in places protected by 
the rocky munitions of Nature. And, on the other hand, birds habituated 
to nesting in sheltered situations, would for a while continue to deposit 
two eggs for a setting. 
The eggs being laid, the female soon commences to incubate. This 
seems to be the exclusive labor of the sex. The fact that she plucks 
the feathers from her abdomen, forming one or two bare spots (according 
to the number which is to compose her complement) with a ridge of 
feathers between them, though circumstantial in character, is the only kind 
of evidence that we have to offer in supj^ort of our assertion. Of the pre- 
cise time required for hatching, we have no knowledge. From the size of 
the egg, and the thickness of its shell, we reason from analogy that it 
cannot be less than twenty-four days. The female is not a constant sitter 
during the daytime, the heated pebbles on clear, sunshiny days supplying 
