350 Louis Agassiz on the Natural 
but the aquatic birds of the family of palmipedes are those which 
especially prevail. The coasts of the continents and of the nume- 
rous islands in the Arctic seas are peopled by clouds of gannets, of 
cormorants, of penguins, of petrels, of ducks, of geese, of mergan- 
sers, and of gulls, some of which are as large as eagles, and, like 
them, live on prey. No reptile is known in this zone. Fishes 
are, however, very numerous, and the rivers espécially swarm with 
a variety of species of the salmon family. A number of represen- 
tatives of the inferior class of worms, of crustacea, of moliusks, of 
echinoderms, and of medusee, are also found here. 
Within the limits of this fauna we meet a peculiar race of men; 
known in America under the name of Esquimaux, and under the 
names of Laplanders, Samoyedes, and Tchuktshes, in the north of 
Asia. This race, so well known since the voyage of Captain Cook 
and the Arctic expeditions of England and Russia, differs alike from 
the Indians of North America, from the whites of Europe, and the 
Mongols of Asia, to whom they are adjacent. The uniformity of 
their characters along the whole range of the Arctic seas forms one 
of the most striking resemblances which these people exhibit to the 
fauna with which they are so closely connected. 
The semi-annual alternation of day and night in the Arctic 
regions has a great influence upon their modes of living. They are 
entirely dependent upon animal food for their sustenance; no fari- 
naceous grains, no nutritious tubercles, no juicy fruits, growing 
under those inhospitable latitudes. Their domesticated animals are, 
the reindeer in Asia and a peculiar variety of the dog, the Esquimaux 
dog in North America, where even the reindeer is not domesticated. 
Though the Arctic fauna is essentially comprised in the Arctic 
circle, its organic limit does. not correspond rigorously to this line, 
but rather to the isotherm of 32° Fahr., the outline of which pre- 
sents numerous undulations. This limit is still more natural when 
it is made to correspond with that of the disappearance of forests. 
It then circumscribes those immense plains of the north which the 
Samoyedes call tundras, and the Anglo-Americans barren lands. 
The naturalists who have overlooked this fauna, and connected it 
with those of the temperate zone, have introduced much confusion in 
the geographical distribution of animals, and have failed to recog- 
nize the remarkable coincidence existing between the extensive range 
of the Arctic race of men, and the uniformity of the animal world 
around the northern Pole. . 
The first column of the accompanying table represents the types 
which characterize best this fauna,—viz., the white or polar bear, 
the walrus, the seal of Greenland, the reindeer, the right whale, 
and the eider duck. The vegetation is represented by the so-called 
reindeer moss—a lichen which constitutes the chief food of the her- 
bivorous animals of the Arctics and the high Alps during winter. 
To the glacial zone, which incloses a single fauna, succeeds the 
