The Eggs of Birds 433 
in the young of many, if not all, other Phyla of animals, 
and which is one of the most interesting provisions brought 
about by the slow but sure working of evolution. We 
may instance the few eggs of the voracious and masterful 
sharks and the millions of spawn necessary to enable 
the halibut and the cod to continue in existence. 
Mr. Ernest Ingersoll has so admirably summed up 
the matter of this relation of the number of eggs to the 
corresponding danger that I cannot do better than to 
follow his argument, quoting his words with a slight 
change here and there. This phase of the study of eggs 
being so clearly understood, it is well worth a little detail 
as an illustration of how interesting all the other problems 
will become when we once get on the right road to their 
solution. 
Among the majority of birds the average number of 
eggs in a nest is from three to six; we may take five as a 
typical average. ‘Any considerable departure from this 
normal number in a species or Family must then be ac- 
counted for by some specific or tribal peculiarity in cir- 
cumstances. 
“Beginning with the ostrichlike group at the bottom 
of the list, we find ourselves face to face with an inter- 
esting state of things, to which the number of eggs is 
an index. Ostriches, rheas, and emeus incubate large 
clutches—a dozen or more,—those inhabiting the conti- 
nents of Africa and South America, however, producing 
twice as many eggs annually as their relatives of Australia 
and the neighbouring smaller islands. 
“Immediately following and contrasting with them are 
