Geographical Regions 321 
In 1853 appeared L. K. Schmarda’s! 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 
devoting many chapters to the possible physical causes and modes of 
dispersal, he divided the land into 21 realms which he shortly charac- 
terises, e.g. Australia as the only country inhabited by marsupials, 
monotremes and meliphagous birds. Ten main marine divisions 
were diagnosed in a similar way. Although some of these realms 
were not badly selected from the point of view of being applicable to 
more than one class of animals, they were obviously too numerous for 
general purposes, and this drawback was overcome, in 1857, by 
P. L. Sclater?. Starting with the idea, that “each species must have 
been created within and over the geographical area, which it 
now occupies,” he concluded “that the most natural primary onto- 
logical divisions of the Earth’s surface” were those six regions, which 
since their adoption by Wallace in his epoch-making work, have become 
classical. Broadly speaking, these six regions are equivalent to the 
great masses of land; they are convenient terms for geographical 
facts, especially since the Palaearctic region expresses the unity of 
Europe with the bulk of Asia. Sclater further brigaded the regions of 
the Old World as Palaeogaea and the two Americas as Neogaea, a 
fundamental mistake, justifiable to a certain extent only since he 
based his regions mainly upon the present distribution of the Passerine 
birds. 
Unfortunately these six regions are not of equal value. The 
Indian countries and the Ethiopian region (Africa south of the 
Sahara) are obviously nothing but the tropical, southern continua- 
tions or appendages of one greater complex. Further, the great 
eastern mass of land is so intimately connected with North America 
that this continent has much more in common with Europe and Asia 
than with South America. Therefore, instead of dividing the world 
longitudinally as Sclater had done, Huxley, in 1868, gave weighty 
reasons for dividing it transversely. Accordingly he established 
two primary divisions, Arctogaea or the North world in a wider 
sense, comprising Sclater’s Indian, African, Palaearctic and Nearctic 
regions; and Notogaea, the Southern world, which he divided into 
1 Die geographische Verbreitung der Thiere. Wien, 1853. 
2 «Qn the general Geographical Distribution of the members of the class Aves,” Proc. 
Linn. Soc. (Zoology), 11. 1858, pp. 130—145. 
3 “On the classification and distribution of the Alectoromorphae and Heteromorphae,” 
Proc, Zool. Soc. 1868, p. 294. 
D. 21 
