webless like the common fowls, its power of swimming as feeble! How could it ever have traversed six hundred miles of sea that separate it from the nearest land intervening between New Zealand and Asia? How pass from the southern extremity of that continent to the nearest island of the Indian Archipelago, and so from member to member of that group to Australia--and yet leave no trace behind of such migration by the arrest of any descendants of the migratory generations in Asia itself, or in any island between Asia and New Zealand? If these facts are inexplicable on the hypothesis of the dispersion of the species of the air-breathing animals from a single Asiatic centre, we must next endeavor to collect analogous facts and classify them, and so try to explain intelligibly, that is agreeably with the facts, the true law or cause of the actual geographical distribution of animals. The laws of geographical distribution, as affecting mammalian life, have been reduced to great exactness by observations continued since the time of Buffon, who first began to generalize about a century ago in that way, noting the peculiarities of the species of South American animals. The most important extension of this branch of zoology has been due to recent researches and discoveries of extinct species of the class Mammalia; and it is chiefly in relation to the modifications of zoological ideas produced by palæontology that a few brief remarks will here be made. The Quadrumana, or order of apes, monkeys, and lemurs, consist of three chief divisions--Catarhines, Platyrhines, and Strepsirhines. The first family is peculiar to the Old World; the second to South America; the third has the majority of its species and its chief genus (Lemur) exclusively in Madagascar. Out of twenty-six known species of Lemuridæ, only six are Asiatic and three are African.