Page:Popular Science Monthly Volume 11.djvu/646

628 contours of 1,000 feet of vertical intervals, and embodying all the results of the author's researches on elevations, accompanies the work. We are informed that, "to express still more clearly the facts brought out by the map, it is the intention of the Survey (Hayden's) to make shortly a relief model of the United States on the basis of this map."

in enforcing his thesis that the "conditions of environment" are the principal factors in modifying species, adduces some very instructive examples of the progressive enlargement of certain peripheral parts of animals as we go from the north to the south. Thus the ears of wolves, foxes, some deer, and hares, are larger in southern than in northern individuals of the same species. In birds, the enlargement of the bill, claws, and tail, is specially noticeable—the bill being peculiarly susceptible of variation. This, the author remarks, accords with the general fact that "all the ornithic types in which the bill is remarkably enlarged occur in the intertropical regions." A similar progressive change southward is remarked in the color of animals, especially birds.

region described in this report by Prof Powell comprises three great geological provinces, designated respectively the Park Province, the Plateau Province, and the Basin Province, succeeding one another in this order from east to west, and all lying east of the Sierra Nevada and west of the great Plains. The whole region is one of considerable geological interest, as presenting on a large scale three great categories of facts, namely, those relating to displacement, degradation, and sedimentation. The formations here studied have an aggregate thickness of 50,000 feet, and embrace strata of the Palæozoic, the Mesozoic, and the Cenozoic ages. The volume is fully illustrated with plates and woodcuts, and accompanied by an atlas of colored maps.

the year ending June, 1876, Lieutenant Wheeler's Survey was organized in two divisions, designed to operate, the one in California, and the other in Colorado and New Mexico. The volume before us, besides the general report of Lieutenant Wheeler, and the executive and descriptive reports of the officers in charge of the California and Colorado divisions, contains several special reports by scientific men attached to the survey, among which we may mention, as possessing a direct popular interest, reports by Dr. Loew on alkaline lakes and mineral springs in Southern California, and on the physical and agricultural features of the same region; a report by Dr. Yarrow on ethnological researches made near Santa Barbara; an analysis by A. S. Gatschet of eleven Indian dialects; last, but by no means least, Lieutenant Bergland's report on the operations of a party commissioned to determine the feasibility of diverting the Colorado River for purposes of irrigation.

insectivorous mammals here described belong to two families, namely: Talpidæ, or moles, and Soricidæ, or shrews. Of moles the author recognizes four good genera as existing in America, namely: Scalops, Scapanus, Condylura, and Urotrichus. Urotrichus is the only one of the four known to be common to both hemispheres. Of European genera of Soricidæ only one, Sorex, is known to occur in America; Blarina is the most characteristic American genus. The third and last of the American genera is Neosorex.

have specially to commend this volume for the many neat graphic charts which it contains. Statistical tables are always dry and confusing, but when they are cast