influence of the solar rays. Facts of this kind indicate the powerful operation of diverse climates in the various coloring of the human skin, and are sufficient to show, that the different complexions of mankind are mere varieties of species, introduced and made permanent by the continued action of local causes. 2. The next most obvious and important of the human differences involves variety of structure, especially in the _shape of the skull_. Taking this as the basis of a classification, Professor Blumenbach proposed a division of mankind into five grand classes—the Caucasian, Mongolian, Ethiopic, American, and Malay, which has been very generally adopted. The principal descriptive particulars of each, as given by that distinguished naturalist, are the following: In the Caucasian race, the head is of the most symmetrical shape, almost round; the forehead of moderate extent; the cheek-bones rather narrow, without any projection; the face straight and oval, with the features tolerably distinct; the nose narrow, and slightly arched; the mouth small, with the lips a little turned out, especially the lower one; and the chin full and rounded. This is the most elegant variety of the human form, and the most perfect examples of it are found in the regions of Western Asia, bordering on Europe, which skirt the southern foot of the vast chain of the Caucasus, from whence the class derives its name, and which is near what is supposed to be the parent spot of the human race. Here are the Circassians and Georgians, the most exquisite models of female beauty. But the Caucasian class includes nations very dissimilar apart from the form of the head. Its members are of all complexions, from the Hindoos and Arabs, some of whom are as black as the Negroes, to the Danes, Swedes, and Norsemen, who are fair, with flaxen hair and light blue eyes. The class comprises the ancient and modern inhabitants of Europe, except the Laplanders and Finns. It comprises also the ancient and modern inhabitants of Western Asia, as far as the Oby, the Belurtagh, and the Ganges—such as the Assyrians, Babylonians, Medes and Persians, Sarmatians, Scythians, Parthians, Jews, Arabs and Syrians, the Turks and Tartars proper, the tribes of Caucasus, the Armenians, Affghans, and Hindoos. It includes likewise the Africans who live on the shores of the Mediterranean, and throughout the Sahara, the Egyptians and Copts, the Abyssinians, and the Guanches, or ancient inhabitants of the Canary Islands, with those Europeans who have colonized America and other parts of the world. The color of the Caucasian class seems mainly to depend on climate, on the degree of solar heat to which there is exposure, for they are all born with light complexions, and become dark only as they grow up, and are more freely acted on by the sun. Their hue is found to deepen by a regular gradation from the farthest north, where the members of this class are very fair, through the olive-colored