as, but lying within the
same climatic zones, are proof of the effective and permanent existence
of barriers preventing an exchange between the original creative
centres.

The first book dealing with the "geography and classification" of the
whole animal kingdom was written by W. Swainson ("A Treatise on
the Geography and Classification of Animals", Lardner's "Cabinet
Cyclopaedia" London, 1835.) in 1835. He saw in the five races of Man
the clue to the mapping of the world into as many "true zoological
divisions," and he reconciled the five continents with his mystical
quinary circles.

Lyell's "Principles of Geology" should have marked a new epoch, since
in his "Elements" he treats of the past history of the globe and the
distribution of animals in time, and in his "Principles" of their
distribution in space in connection with the actual changes undergone by
the surface of the world. But as the sub-title of his great work "Modern
changes of the Earth and its inhabitants" indicates, he restricted
himself to comparatively minor changes, and, emphatically believing
in the permanency of the great oceans, his numerous and careful
interpretations of the effect of the geological changes upon the
dispersal of animals did after all advance the problem but little.

Hitherto the marine faunas had been neglected. This was remedied by E.
Forbes, who established nine homozoic zones, based mainly on the study
of the mollusca, the determining factors being to a great extent
the isotherms of the sea, whilst the 25 provinces were given by the
configuration of the land. He was followed by J.D. Dana, who, taking
principally the Crustacea as a basis, and as leading factors the mean
temperatures of the coldest and of the warmest months, established
five latitudinal zones. By using these as divisors into an American,
Afro-European, Oriental, Arctic and Antarctic realm, most of which were
limited by an eastern and western land-boundary, he arrived at about
threescore provinces.

In 1853 appeared L.K. Schmarda's ("Die geographische Verbreitung der
Thiere", Wien, 1853.) two volumes, embracing the whole subject. Various
centres of creation being, according to him, still traceable, he formed
the hypothesis that these centres were originally islands, which later
became enlarged and joined together to form the great continents, so
that the original faunas could overlap and mix whilst still remaining
pure at their respective centres. After devot