ving under different
circumstances,--on open, sterile plains, where they have to run down their
own prey,--on rocky coasts, where they have to feed on crabs and fish left
in the tidal pools, as in the case of New Guinea and Tierra del Fuego. In
this latter country, as I am informed by Mr. Bridges, the Catechist to the
Mission, the dogs turn over the stones on the shore to catch the
crustaceans which lie beneath, and they "are clever enough to knock off the
shell-fish at a first blow;" for if this be not done, shell-fish are well
known to have an almost invincible power of adhesion.

It has already been remarked that dogs differ in the degree to which their
feet are webbed. In dogs of the Newfoundland breed, which are eminently
aquatic in their habits, the skin, according to Isidore Geoffroy,[78]
extends to the third phalanges, whilst in ordinary dogs it extends only to
the second. In two Newfoundland dogs which I examined, when the toes were
stretched apart and viewed on the under side, the skin extended in a nearly
straight line between the outer margins of the balls of the toes; whereas,
in two terriers of distinct sub-breeds, the skin viewed in the same manner
was deeply scooped out. In Canada there is a dog which is peculiar to the
country and common there, and this has "half-webbed feet and is fond of the
water."[79] English otter-hounds are said to have webbed feet: a friend
examined for me the feet of two, in comparison {40} with the feet of some
harriers and bloodhounds; he found the skin variable in extent in all, but
more developed in the otter than in the other hounds.[80] As aquatic
animals which belong to quite different orders have webbed feet, there can
be no doubt that this structure would be serviceable to dogs that frequent
the water. We may confidently infer that no man ever selected his
water-dogs by the extent to which the skin was developed between their
toes; but what he does, is to preserve and breed from those individuals
which hunt best in the water, or best retrieve wounded game, and thus he
unconsciously selects dogs with feet slightly better webbed. Man thus
closely imitates Natural Selection. We have an excellent illustration of
this same process in North America, where, according to Sir J.
Richardson,[81] all the wolves, foxes, and aboriginal domestic dogs have
their feet broader than in the corresponding species of the Old World, and
"well calculated for running on the snow." Now, in these