242 THE ZOOLOGIST. 
The majority of fishes, amphibians, and reptiles, from 
which latter, it must be acknowledged, our birds are derived, 
possess no parental instinct which is so remarkable a charac- 
teristic of the birds. But most animals possess that very 
elementary kind of parental instinct—typical of the insects— 
which informs them of the most suitable places for the dropping 
of their eggs. 
Similarly, in ages long ago, the females of birds probably 
dropped their eggs at random in a variety of situations in more 
or less suitable localities on the ground. No special receptacle 
was made, but the eggs were laid in just those places where the 
female happened to be at the time of her accouchement; so that 
the eggs of a single female were scattered one by one over per- 
haps a wide area. These eggs, left with heartless nonchalance 
by the parents, would be hatched by the heat of the sun, or by 
inanimate substances. The young, at hatching, would be per- 
fectly capable of looking after themselves. Possibly they would 
be able to fly within an hour or so. 
In cold climates the sun would not be hot enough for the 
hatching of eggs, but at that time the eggs may have materially 
differed from those of to-day in the amount of heat required, 
while the two hemispheres may have been generally warmer, 
for even the Arctic Regions show abundant evidence of having 
been favoured—in the Cretaceous epoch, for example—with a 
hot climate and rich vegetable life. The gradual decline of this 
heat and the approach of Arctic conditions were no doubt instru- 
mental in inducing parental affection and increasing the incuba- 
tion duties. A few species which still resort to the heat of the | 
sun now linger in the Tropics. 
Many species in a fit of carelessness occasionally, even at the 
present time, drop their eggs on the bare ground and leave them, 
vig. many of the ground birds, Molothrus vulgaris and Sturnus 
vulgaris, and others. 
These primitive birds, with little or no parental instinct, 
laid a very large number of large eggs. 
The reason for this was that the risks to which the eggs were 
exposed were very great, and only a few of the embryos which 
happened to fall in with suitable circumstances would ever arrive 
at maturity. The eggs were large in order to contain the in- 
