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On the Geographical Distribution of Animal Life. By A. R. WALLACE.

The author called attention to the six geographical regions established by Dr. Sclater (Proc. Linn. Soc., Feb. 1858) for ornithology—viz., 1st, the Neotropical, comprising South America and the West Indies; 2nd, the Nearctic, including the rest of North America; 3rd, the Palæarctic, composed of Europe, Northern Asia to Japan, and Africa, north of the Desert; 4th, the Ethiopian, which contains the rest of Africa and Madagascar; 5th, the Indian, containing Southern Asia and the western half of the Malay archipelago; and 6th, the Australian, which comprised the eastern half of the Malay Islands, Australia, and most of the Pacific Islands. It was stated that these regions would apply almost equally well to mammalia, reptiles, land-shells, and insects; but there were some exceptional cases, which it had been thought would render these regions inapplicable to zoology generally. These exceptional cases were—1st, that the batrachians of Japan are Palæarctic, agreeing with the birds, &c.; but the snakes are altogether Indian, as

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pointed out by Dr. Günther in his paper on the geographical distribution of reptiles (Proc. Zool. Soc. 1858, p. 373); 2nd, that the mammalia of North Africa are not European, like the birds; 3rd, that the insects of the Moluccas and New Guinea are generally of Indian forms, while the birds and mammals are Australian; and, 4th, that the insects of Chili are of North-Temperate and Australian forms, while the birds and mammals are mostly of true South-American groups. These cases were treated successively; and it was shown that the statement as to the mammals of North Africa was incorrect, and that they really very strongly confirmed the evidence of the birds and reptiles as to that country being Palæarctic. In the other cases the anomalies of distribution were explained as being due to special exceptional circumstances, which should not invalidate the general accuracy and usefulness of these divisions. The discrepancies in the distribution of plants, which, while often agreeing with those of insects, were much greater, were supposed to be in a great measure due to the adventitious action of the glacial epoch and of floating ice. In conclusion, naturalists were called upon to furnish detailed information as to the agreement or discrepancies of this system of geographical regions in the groups to which they paid special attention, so that a final conclusion might be arrived at as to the advisability of adopting them for general use.