In the present report, Mr. Curtis gives a clear and systematically ordered description of the district, its geology, and the several mining locations, with their characteristic features. Among the topics particularly considered arc the surface geology, the structure, and the ores of Prospect Mountain and Ruby Hill, the ore deposits, the source and manner of deposition of the ores, the occurrence of water in the mines, the methods of mining and timbering, and of working the ores, an account of Adams Hill, and "the future of the Eureka district." We are pleased to observe that Mr. Curtis's work in this field has elicited warm commendation and high testimonials to its value from foreign experts: Herr V. Groddeck, Director of the Clausthal School of Mines, Austria, having studied the report "with the greatest interest," has expressed his appreciation of "the instruction and suggestions contained in it," and adds: "It is always wonderfully pleasing to me to see with what intensity and with what rich results your country pursues the study of ore deposits." Herr F. Posepny, Inspector of Mines for Austria, who has visited Eureka, and has drawn some interesting comparisons between its features and those of some of the Hungarian mines, characterizes this work as one which "is destined to play an important part in the technical literature of ore deposits. When I glance over what I know from actual inspection, and what I know through the literature of the ore deposits of your country, I am more and more convinced that North America will be the coming school for the study of ore deposits." Herr Posepny adds that he is much interested in the results of Mr. Curtis's examination of country rock for minute quantities of metals, as the subject has been taken up in his own country from a practical stand-point.
Memoirs of the National Academy of Sciences. Vol. II., 1883. Washington: Government Printing Office. Pp. 202.
The present volume contains four memoirs, of which the most voluminous is the full account of the eclipse of the sun, of May, 1883, and of the United States Expedition to Caroline Island, in the South Pacific Ocean, to view it. Included in this memoir arc several special papers of considerable general interest, among which are the narrative of the voyage to Caroline Island and return, the history and general description of the island, various scientific and technical memoranda respecting it, its botany, zoölogy, and butterflies; and particular reports of eclipse observations by eleven associates of the expedition. The whole is attractively illustrated with maps and views of the island and its peculiar scenery, and representations of various features of the eclipse. The second memoir is Professor S. P. Langley's paper on the "Experimental Determination of Wavelengths in the Invisible Prismatic Spectrum"; the third is by Professor William H. Brewer, "On the Subsidence of Particles in Liquids"; and the fourth is the paper of Alexander Graham Bell "Upon the Formation of a Deaf Variety of the Human Race," of which we have already given a brief abstract.
Dinocerata. (United States Geological Survey, Vol. X.) By Othniel C. Marsh, in charge of the Division of Paleontology. Washington.
This monograph contains the full record of an extinct order of mammals, of which the author has made special studies. The only locality where remains of the Dinocerata have been found is an Eocene lake-basin in Wyoming, and there his first discoveries were made by Professor Marsh in 1870. The specimens collected in this and successive expeditions are now in the museum at Yale College, and represent more than two hundred individuals of the Dinocerata, besides the remains of many other vertebrata hitherto unknown. Seventy-five of these have portions of the skull preserved, and in more than twenty it is in good condition. Three genera have been established in this order: Dinocera, Marsh; Tinoceras, Marsh; and Uintatherium, Leidy. The skull of Dinoceras mirabile is long and narrow; it supports on the top three pairs of bony elevations or horn-cores, which form its most conspicuous feature, and suggested the name of the genus (δενός, terrible, and κέρς, a horn). There are no upper incisors; the canines in the male are enormously developed, forming sharp, trenchant, decurved tusks. The brain of the Dinocerata is se-
