latter kind of selection resulting from the occasional preservation, during
hundreds of generations, of those individual dogs which were the most
useful to man for certain purposes and under certain conditions of life. In
a future chapter on Selection I shall show that even barbarians attend
closely to the qualities of their dogs. This unconscious selection by man
would be aided by a kind of natural selection; for the dogs of savages have
partly to gain their own subsistence: for instance, in Australia, as we
hear from Mr. Nind (1/77. Quoted by Mr. Galton 'Domestication of Animals'
page 13.), the dogs are sometimes compelled by want to leave their masters
and provide for themselves; but in a few days they generally return. And we
may infer that dogs of different shapes, sizes, and habits, would have the
best chance of surviving 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 (1/78.
'Hist. Nat. Gen.' tome 3 page 450.), 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