664 ZOOLOGY. 
It appears, then, that each continent has had from the 
first its distinct assemblage of life, and thus opposing con- 
tinents, such as South America and Africa, have fundament- 
ally different faune, because they have had a separate geo- 
logical history. Though the climate, moisture, and extent 
of forests of Brazil and the West Coast of Africa may, for 
example, be nearly identical, the animals are of a different 
type. At the present day, Australian trees may be trans- 
planted to California, and flourish there, and camels from 
the Orient may breed in Southern California, because at the 
present day the climate and soil are so much alike in the two 
countries. 
Distribution of Marine Animals._Nearly all that has 
been said thus far applies to land animals. Marine species 
are assorted into faune which are nearly as well marked as 
terrestrial assemblages of species. The barriers restraining 
them within their faunal limits are the temperature of the 
water, this being modified more or less by the ocean-cur- 
rents, the nature of the shore, whether rocky or muddy or 
sandy, and the nature of the sea-bottom, whether also 
rocky, muddy, orsandy. Many marine animals live attached 
to rocks and stationary pebbles, others are found only in 
coarse or in fine sand, while the muddy bottoms of harbors, 
bays, and gulfs, or the soft, deep ooze of the ocean-depths 
harbor a different assemblage of mud-loving species. The 
temperature of the water is the most important agency now 
in operation in the limitation of marine animals. Thus 
there is a tropical, north and south temperate, an arctic 
and probably an antarctic zone, and these are, along the 
shores of the different continents, subdivided into distinct 
faune. For example, along the coast of Eastern North 
America, the arctic or circumpolar fauna extends from the 
polar regions to Labrador and Newfoundland ; a second, 
the Acadian, to Cape Cod; between Cape Cod and Cape 
Hatteras another assemblage (the Virginian) is found ; from 
Cape Hatteras to Southern Florida a fourth, and the Flor- 
idan peninsula belongs to the tropical regions. Along these 
different areas the water is of different temperatures. We 
also find a large proportion of circumpolar animals in the 
