Scientific Serials

Abstract

American Journal of Science, March.—Prof. Marsh's monograph on the Dinocerata, by L. P. B. This valuable contribution to American palæontology forms a sequel to the author's work on the Odontornithes, or birds with teeth, and contains a full account of the peculiar order of mammals discovered by him during the last fifteen years in the early tertiary formations of the great central plateau in Wyoming. The old lacustrine basin of this region, where alone the remains of Dinocerata have hitherto been found, have already yielded parts of over 200 individuals, which are now grouped in three genera: Dinoceras, Marsh; Tinoceras, Marsh; and Uintatherium, Leidy, The last-named appears to be the most primitive type, and Tinoceras the most specialised, Dinoceras being intermediate. Of species the number cannot yet be determined, but thirty more or less distinct forms have already been recognised. In stature and movements it appears to have resembled the elephant as much as any other known type, differing from it especially in the shape of the skull, remarkably small brain, longer neck, and more bent fore limbs. It was by far the largest of all known Eocene animals. The paper is enriched with numerous illustrations, and with a map showing the region of Dinoceras beds.— On Taconic rocks and stratigraphy, with a geological map of the Taconic region, by James D. Dana. In this paper the author embodies the results of a fresh study, begun in 1882, of the Taconic region extending over parts of Massachusetts, Connecticut, Vermont, and New York. The rocks described comprise the Taconic skirts of the Taconic range, and subordinate ridges within tire adjoining limestone area; the limestone formations on the east and west sides of the Taconic range; and the quartzite adjoining or within the limestone area. All these rocks are regarded as belonging to one system of Lower Silurian age, with the Taconic schists as the upper member of the series. The map is to a scale of half an inch to the mile.—Variations of latitude, by Asaph Hall. The author deals with Signor Pergola's recently-proposed plan for investigating variations of latitude by special series of observations made with the best prime vertical transit instruments on selected lists of stars. A chief feature of the plan is that the work is to be mainly differential, two observatories under the same or nearly the same latitude co-operating.—Notes on the Jurassic strata of North America, by Charles A. White. The paper is mainly a reply to the objections raised by Mr. J. F. Whiteaves, of the Canadian Geological Survey against the classification of certain exposed formations frequently occurring throughout Colorado, Wyoming, Dakota, Utah, and Montana, and usually referred to the Jurassic period.—Meteoric iron from Coahuila, Mexico, by M. T. Lupton. An analysis of a fragment of this meteoric mass, weighing about 192 lbs., yielded: iron, 91.86; nickel, 7.42; cobalt, 50; phosphorus, .27.—Optical projection of acoustic curves, by W. Le Conte Stevens. Optical presentations of a concord and a discord arc shown projected on a screen by a simple and ingenious process.—Measurement of strong electrical currents, by John Trowbridge.—Divisibility of the Archæan formations in the North-West, by R. D. Irving. The region here investigated occupies, as indicated by the accompanying sketch-map, a tract some sixty miles in length between Lake Numakagon, in North Wisconsin, and Lake Gogebic, in North Michigan. The Archæan rocks of this district are referred to the Huronian and Laurentian systems.—Mineralogical notes, by W. E. Hidden. Specimens are described of phenacite and Xenotine, from new localities; of Fayalite, from Colorado; of Zircon, from Canada; and of zutile and emeralds, from North Carolina.