history of geology. While these faunas arc remarkable for the great number and variety of the species and individuals, and also for the enormous size of some of their forms, it is in other directions that their highest interest lies. By their anomalous and altogether unexpected characters, by their strange combination and dissociation of peculiarities of structure, they throw a flood of light on the question of evolution, and give us a key to the development of the existing creation that, before their discovery, it was too much to expect we should ever possess." The most important service, Professor Orton further remarked, that has been rendered in the American field, is the recent mapping of the great moraine from the Atlantic border to Dakota. On "the unfinished problems relating to the geology and chemistry of coal," Professor Orton enumerated the four principal theories of the formation of coal-beds, inclining to favor the peat-bog theory of Lesquereux and Brongniart. In accounting for coal-fields—a succession of coal-beds separated by marine formations and inorganic sediments of sandstone and iron-ore—we have to seek an explanation of the regularity of the intervals, and arc referred to Croll's theory of an astronomical cause. Various unsettled questions also appear on the chemical side; and, while much has been done, much remains to be done in the field of the microscopical structure of coal. These problems will probably all be solved, but when that is done, "out of these old carboniferous swamps, new questions, larger, deeper than any we now see, will perpetually arise to stimulate by their discovery and to reward by their solution that love of knowledge for its own sake which makes us men." Captain E. L. Corthell presented a paper, which was read at a general meeting, on the contractions of the earth's crust and surplusage in mountain-structure. New discoveries of fossils in the older strata of various regions were announced. Professor Henry S. Williams presented a paper on the comparative stratigraphy of the southern counties of New | York and the adjoining counties of Pennsylvania, and Northern Ohio as far as Cleveland. Professor E. W. Claypole discussed the problem of the origin of the palæozoic sediments of Pennsylvania. Professor Lewis E. nicks described the structure and relation of the Dakota group in Nebraska. Mr. G. K. Gilbert described an old shore-line of Lake Ontario, which he had traced half-way about its basin. Professor A. R. Crandall described some small volcanic dikes which have recently been discovered in Elliot County, Kentucky. Professor Orton described the gas and oil wells of Northwestern Ohio, in the region of which Findlay is the center, and whose sources of supply are in formations lower than any from which gas has been known before to issue. The flow of gas ranges in the various wells from 100,000 to 1,200,000 cubic feet per day. The petroleum is not very abundant, and is black, sulphurous, and of a gravity of about 35°. The formation whence the gas and oil issue is a porous magnesian limestone identified as Trenton. Professor A. C. Worthen described the quaternary deposits of Central and Southern Illinois as observed in cutting coal-mine shafts through them. The bedrock surface is diversified by valleys much as the drift surface above, but with a different drainage system. At the bottom is a stratified clay, in part gravelly, which appears to be derived from the waste of the bed-rock. Above this is a forest-bed, which, though not a universal feature, is so widely spread as to make much of the well-water unfit for use. Over this lies a blue and yellow gravelly clay, with glaciated bowlders sometimes as large as two feet in diameter; and, finally, a few feet of loess, covered with a thin bed of fine clay.
Educational Museums.—Dr. Burt G. Wilder, addressing the Biological Section of the American Association on "Educational Museums of Vertebrates," maintained that every institution, of whatever grade, should have one. In selection quality is more important than quantity, and arrangement is usually more needed than acquisition. As a rule, each specimen should teach but one thing, and that thoroughly. The same form may, therefore, properly recur in several parts of the museum, to illustrate different parts or ideas. True economy consists in paying liberally for what is wanted, rather than in taking what is not wanted as a gift. "In addition to, or in place of, the three great series—
