. The Cambridge natural history. Zoology. GEOGRAPHICAL DISTRIBUTION 95 there are not a few resemblances between tliis Eastern Asiatic and the American fauna. The Urodela thus lend no support to the usual division of the Periarctic into a Palaearctic and a Nearctic sub-region. Xor is it possible to divide the I'alaearctic into a Eurasian and a Mediterranean province. We have in this case to distinguish between an American, an Asiatic, and a European. ^=SALAM. LECHRIODONTA. Illllll .§SS-ICHTHYODEA Fig. 16.—Map showing the distribution of the Urodela. " Ichthyodea " — Amphi


. The Cambridge natural history. Zoology. GEOGRAPHICAL DISTRIBUTION 95 there are not a few resemblances between tliis Eastern Asiatic and the American fauna. The Urodela thus lend no support to the usual division of the Periarctic into a Palaearctic and a Nearctic sub-region. Xor is it possible to divide the I'alaearctic into a Eurasian and a Mediterranean province. We have in this case to distinguish between an American, an Asiatic, and a European. ^=SALAM. LECHRIODONTA. Illllll .§SS-ICHTHYODEA Fig. 16.—Map showing the distribution of the Urodela. " Ichthyodea " — Amphiumidae + Proteidae + Sireuidae. fauna. The Asiatic or Eastern Palaearctic sub-region assumes the central position, at least from a merely geographical point of view. It would be unjustifiable to assume a spreading from this centre into Europe, and, on the other hand, into America. The centre existed more probably in the Arctic circle, now devoid of Urodela. So far as mere numbers of species are concerned the huge Asiatic or Eastern Palaearctic region is the poorest, but it is also the least explored, and China will probably yield a good many new forms. We know at present only 15 species, nearly all from the eastern half. These 15 species represent no less than 11 genera, 8 of which (=73 per cent) are peculiar to the sub-region. Next comes the Western Palaearctic or European sub-region with about '21 recent species of 5 genera, 4 of which are peculiar. America is by far the richest, with uo less than 66 species (36 eastern, about 16 western, and the rest Central American, etc.), belonging to 19 genera, 17 of which ( = 90 per cent) are peculiar to the New World. But this richness in species is due mainly to the abundance of the two genera Ainhh/stoma and Spelerpes, just as Europe is characterised by its many Tritons. One of the most striking features of the Asiatic sub-region is. Please note that these images are extracted from scanned page images that may have been digitall


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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895