Geology and Natural History. 161 



Triisodontidae, Mesonychidae, Proviverridae, Hyaenodontidae, Palae- 

 onictidae, Miacidae ; and then notes follow on the genera referred 

 to these groups. 



The same volume of the Proceedings of the Academy (p. 326) 

 contains a note by Prof. Cope on the discovery of remains of 

 Hymna and other Carnivores in the Pliocene Blanco beds on the 

 Llano Estacado in western Texas. The Hyaena — the first found 

 in America — is named the Borophagus diversidens. One of the 

 other Carnivores, is a Weasel, and is named by Prof. Cope 

 Canimartes Cumminsii, after its discoverer ; and a third, lelis 

 Hillianus, after Prof. R. T. Hill. 



Memoir on the Genus Pahvosyops of Leidy and its allies, by 

 Charles Earle. pp. 267-388, 4to, of the Journal of the Acad- 

 emy of Natural Sciences of Philadelphia, vol. ix (Oct., 1892). — 

 This able monograph on the genus Palceosyops, 120 pages in 

 length and illustrated by five plates, is based on the study of the 

 collections of the Philadelphia Academy, those of Prof. Cope, 

 others of the Princeton Museum, and specimens in the Yale Col- 

 lege Museum. The Princeton collections, obtained in four expe- 

 ditions to the region under the leadership of Professors Scott and 

 Osborn, are especially large, and have enabled the author to add 

 to his many excellent illustrations a restoration of Leidy's 

 Palceosyops paludosus. With regard to the relations of the 

 genus, he says : " I think that Palceosyops and the allied genera, 

 Diplacodon, and Titanotheriiim, should be placed in "the family 

 Titanotheriidae." As the prefatory remarks state, " the association 

 of the renowned name of Dr. Joseph Leidy with this genus gives 

 to these investigations especial interest at the present time." 



2. Geology of the JEureha District, by Arnold Hague. 396 

 pp. 4to, with 8 plates and a folio Atlas of 13 plates. Volume XX, 

 of the Memoirs of the U. S. Geological Survey. — This volume, 

 besides treating of the general geology and ores of the Eureka 

 region, discusses at length the nature and origin of its igneous 

 rocks. The system of flexures and iaults in the rocks is referred 

 to time after the Carboniferous and before the close of the 

 Jurassic period. No Mesozoic rocks occur in the region. The 

 igneous rocks are termed volcanic ; but no volcanoes are reported ; 

 instead, the eruptions were along the old faults of the region, and 

 through fissures made at the time of the eruptions. The ejection 

 of the andesites and rhyolites was followed by the deposition of 

 the ores, and the latter are stated to have come up from below as 

 the result of solfataric action which accompanied the igneous 

 action, but as having become more or less changed into different 

 kinds, and distributed by the prolonged continuance of this action. 



The final conclusions of the author as to the relations and origin 

 of the igneous rocks, are presented in a closing summary as fol- 

 lows (p. ""289). 



The Eureka District presents a most instructive volcanic region 

 standing quite apart from all other centers of similar eruption, 

 yet, in the nature of its extravasated material, typical of many 

 localities in the Great Basin. 



