which Friestley, as he tells us, imparted to the French chemists was used by them with crushing effect against his favourite theory. The discovery of oxygen was the deathblow to phlogiston. Here was the thing which had been groped for for years, and which many men had even stumbled over in the searching, but had never grasped. Priestley indeed grasped it, but he failed to see the magnitude and true importance of what he had found. It was far otherwise with Lavoisier. He at once recognised in Priestley's new air the one fact needed to complete the overthrow of Stahl's doctrine; and now every stronghold of phlogistonism was in turn made to yield. Priestley, however, never surrendered, even when every phlogistian but he had given up the fight or gone over to the enemy. When age compelled him to leave his laboratory he continued to serve the old cause in his study, and almost his last publication was his "Doctrine of Phlogiston Established." His own life, indeed, affords an exemplification of the truth of his own words, that "we may take a maxim so strongly for granted, that the plainest evidence of sense will not entirely change, and often hardly modify, our persuasions; and the more ingenious a man is, the more effectually he is entangled in his errors, his ingenuity only helping him to deceive himself by evading the force of truth." The Geographical Distribution of Mammals. A LECTURE, Delivered in the Hulme Town Hall, Manchester, on Wednesday, November 25th, 1874. By P. L. SCLATER, Esq., M.A., F.R.S., Secretary to the Zoological Society of London. NIMALS and plants of various sorts and kinds are found all over the surface of the globe which we inhabit, from the poles to the equator, and from the lowest valleys to far above the snow-limit of the highest mountains. The rivers, lakes, and oceans that cover a large portion of the earth's surface are likewise replete with life. Recent discoveries have shown that even the profoundest depths of the Atlantic, formerly supposed to be utterly void of organic life, are tenanted by numerous forms of living beings. Now, these multitudes of plants and animals are not scattered broadcast over the earth's surface, as the casual observer might suppose; nor do they vary according to the modifications of climate or of any other set of external circumstances, as an unlearned person might well imagine. But they are distributed strictly according to certain natural laws, concerning our present knowledge of which-more especially as regards one class of animals, that of Mammals-I have to speak to you on the present occasion. Before, however, I begin to treat of the geographical distribution of Mammals specially, I must say a few words as to what we know generally of the manner in which living organisms, whether plants or animals, are arranged over the world which we inhabit. Let us take two distant parts of the world-England and New South Wales for example, and study their natural productions respectively. The "Fauna" and "Flora," as the sums of the animal and vegetable life are called, of these two countries, when compared together, are found to be almost entirely different. On examining the indigenous animals and plants found in the vicinity of London, and comparing them with those observed in the neighbourhood of Sydney, or of any other part of Australia, the naturalist will find them to be utterly dissimilar. Instead of foxes and hares, the woods are tenanted by kangaroos. In place of squirrels, opossums climb about the trees. Instead of sparrows and thrushes, parrots and honeyeaters abound. So likewise the snakes, frogs, insects, snails, and plants met with during a walk in the Australian bush would be quite different from the corresponding objects met with in the neighbourhood of this city. But let our roving naturalist shift his quarters from Australia half-way home towards England, and make a similar investigation in the neighbourhood of Calcutta. Here in India he will still find the animals and plants very different from those of his native shores, although not so different as those of Sydney. If he approaches still nearer-say to Egypt, there will be a much greater resemblance between the two floras and faunas; and finally, when he reaches Paris, the animal and vegetable productions, when compared with those of Middlesex, will be found to be almost, although not quite, identical. But it will be said that these variations in animal and vegetable life may be attributable to climate. That this, however, is not the case, is at once shown by the comparison of the natural products of far-distant places of which the climate is as nearly as possible similar. Take, for example, three spots under the equator-in America, Africa, and Asia. Their faunas and floras will be found to be completely different; so much so, that a single insect, a single bird, or a single plant, out of a collection made in one of them, would usually enable the naturalist to say at a glance from which of the three spots it had been procured. Again, take the two polar extremities of the earth, of which the climates are nearly similar. Their natural products are utterly different. At the North Pole we meet with ice-bears, seals, and awks; at the South Pole, sea-lions, sea-leopards, and penguins. It is, therefore, manifest, and has been clearly shown by naturalists, that differences in the animals and plants of different countries cannot be accounted for by climate. At the same time, there can be no question that certain groups of animals specially affect particular climates, and are only found where these prevail. The process of comparison of the organic beings of far and near countries may be (and has been) carried on to any extent, and the result arrived at has been the discovery of the following general law-which, however, like most general laws, admits of exceptions: That the more distant countries are, the more dissimilar are their animals and plants; and the nearer they are, the more similar are their animals and plants. So certain, indeed, has the law been found to be of adjoining countries producing similar or nearly similar animals and plants, that the converse of this proposition is now generally accepted by naturalists namely, that if the animals and plants of two countries are alike, they must either now be or recently have been in geographical connection. I will point out a few instances on the map of the way in which this argument has been used. (1) The Antilles, or West India Islands, have in many respects a peculiar fauna; that is, contain a certain number of animals not known to occur elsewhere. But in Trinidad-the most remote of them-these animals do not occur, but another set, the same as those of Venezuela, are found. It is therefore evident, if the last proposition put before you be true, that Trinidad is merely a little bit of the South American continent, broken off at a comparatively recent epoch. And this, I believe, has also been shown to be the case from an examination of its geological structure. (2) In the same way we know that the animals and plants of the British Islands are identical, or very nearly so, with those of the rest of Northern Europe. And we conclude therefore, as is likewise manifest from geological investigations, that the Straits of Dover are of comparatively recent formation. (3) A third well-known instance is afforded by the islands of Sumatra, Java, and Borneo. Java is much nearer to Sumatra than Borneo. But the animals of Sumatra and Borneo are very nearly alike, whereas those of Java are in many cases different. It has been argued, therefore, and will no doubt be ultimately found to have been the case, that Sumatra has been joined to Borneo more recently than to Java. But in comparing the animals and plants of two countries, it is not only necessary to ascertain, in such cases as these and others, merely whether they agree or differ-we must know exactly how far and to what degree they are like or unlike. To this end it is necessary to understand the mode of estimation of the similarities of animals (for we will in future speak only of animals, although plants follow nearly the same laws) which is usually employed by Naturalists. The aggregation of all the similar individuals of any one animal that now live, or that have recently lived in the world, is called à "species." Thus, when we speak of "The Lion," or Felis leo-as a scientific naturalist would call it-we understand by that term, not one particular lion, but all the lions that have lately lived, or now do live, on the earth's surface, or lion-kind in general, just as by the term mankind we mean men (and women) in general. The lion (Felis leo) has a particular structure, shape, and colour, which distinguish it from all other kinds of cats, and, indeed, from all other known animals. This particular structure, shape, and colour, constitute what are called its "specific" characters, or marks by which any lion may be distinguished from a tiger, or a leopard, or any other animal. But, besides these specific characters, the species lion (Felis leo) possesses another important attribute, namely, that of being found in a natural state only within a certain limited part of the world's surface. Over this district are distributed, in greater or less numbers, the various individuals which together make up the whole species. And this district is called the "range," "habitat," or "specific area" of the lion (Felis leo). The existing "specific area" of the lion (Felis leo) comprehends Africa and South-western Asia up to Central India. I say existing, because we know that the areas of many animals have been materially altered, even during the historic period. Thus, the lion occurred in South-eastern Europe in the days of the Persian invasion, and in preceding geological epochs was abundant all over the continent, and even in England itself. But although the lion and all other animals, especially the larger forms, which are least easily reconciled with man's presence, are continually altering their ranges or specific areas, this alteration is a slow, in many instances secular, process; so that for all practical purposes the "range" or specific area of an animal may be considered, like the rest of its specific characters, to be constant. Let us now take other species of the larger and better-known cats: The tiger (F. tigris): Southern and Central Asia. The wild-cat (F. catus): Northern and Central Europe. The serval (Felis serval): Africa. The puma (F concdor): Central and South America. The pampas cat (F. passerum): pampas of South America. Each species, it will be observed, has a distinct and definite |