back to reptiles, e.g. in being an
egg-layer, in having comparatively large eggs, and in being imperfectly
warm-blooded. It swims well and feeds on small water-animals. It can
also burrow.]

Evolution of the Voice

The first use of the voice was probably that indicated by our frogs and
toads--it serves as a sex-call. That is the meaning of the trumpeting
with which frogs herald the spring, and it is often only in the males
that the voice is well developed. But if we look forward, past
Amphibians altogether, we find the voice becoming a maternal call
helping to secure the safety of the young--a use very obvious when young
birds squat motionless at the sound of the parent's danger-note. Later
on, probably, the voice became an infantile call, as when the unhatched
crocodile pipes from within the deeply buried egg, signalling to the
mother that it is time to be unearthed. Higher still the voice expresses
emotion, as in the song of birds, often outside the limits of the
breeding time. Later still, particular sounds become words, signifying
particular things or feelings, such as "food," "danger," "home,"
"anger," and "joy." Finally words become a medium of social intercourse
and as symbols help to make it possible for man to reason.

Sec. 2

The Early Reptiles

In the _Permian_ period reptiles appeared, or perhaps one should say,
began to assert themselves. That is to say, there was an emergence of
backboned animals which were free from water and relinquished the method
of breathing by gills, which Amphibians retained in their young stages
at least. The unhatched or unborn reptile breathes by means of a
vascular hood spread underneath the egg-shell and absorbing dry air from
without. It is an interesting point that this vascular hood, called the
allantois, is represented in the Amphibians by an unimportant bladder
growing out from the hind end of the food-canal. A great step in
evolution was implied in the origin of this ante-natal hood or foetal
membrane and another one--of protective significance--called the amnion,
which forms a water-bag over the delicate embryo. The step meant total
emancipation from the water and from gill-breathing, and the two
foetal membranes, the amnion and the allantois, persist not only in
all reptiles but in birds and mammals as well. These higher Vertebrates
are therefore called Amniota in contrast to the Lower Vertebrates or
Anamnia (the Amphibians, Fishes, and primitive types).

I