300 ANNUAL OF SCIENTIFIC DISCOVERY. 



from metamorphism, partly from denudation, or perhaps they may never 

 have been deposited. 



Mr. Lesquereux compares the New England basin with the others as 

 follows : " From your very interesting section of Aquidneck Inland, it appears 

 that near or at the western limits of the coal fields of North America the 

 multiplication of conglomerate strata analogous to that which is found in 

 Nova, Scotia is already evident. Thus your coal fields of Massachusetts and 

 Rhode Island look as forming a link of transition between the coal basin of 

 the Great Appalachian and Western region, and that of Nova Scotia. Indeed, 

 the difference is easily marked and understood. To the eastward, the sand- 

 stones, conglomerates, or shore materials, predominate; to the westward, on 

 the contrary, the limestone and marine formation becomes more marked. 

 It is the only difference." 



ON THE GEOLOGY OF NEBRASKA. 



At a recent meeting of the American Philosophical Society, Professor 

 Leidy gave the following account of the geology of the Territory of Ne- 

 braska : 



This great territory, embracing upwards of one hundred and thirty thou- 

 sand square miles, is composed of formations of the cretaceous and later 

 tertiary periods, with here and there a protrusion of metamorphic rocks. 

 Watered by the man}- western tributaries of the Missouri, almost all of these, 

 so far as they have been explored, have yielded large numbers of species of 

 extinct organic forms, vegetable and animal. 



From the Mauvaises Terres of White river, a miocene tertiary fresh-water 

 formation, apparently a lacustrine deposit, an immense quantity of fossil 

 bones of extinct mammals and turtles have been collected. In collections 

 made by gentlemen of the Fur Company, by Jesuit missionaries, by Dr. Hay- 

 den, arid in others obtained under the auspices of the government, the Smith- 

 sonian Institution, and Professor James Hall, altogether forming from six to 

 eight thousand pounds of fossils, submitted to Dr. Leidy's inspection, he had 

 detected the remains of thirty extinct mammals, and one turtle. Of these 

 there are ten species of the extinct genera of ruminants, Oreodon, Agr/'o- 

 chrcrns, Poebro-flierium, Dorca-therium, Leptauchenia, and Protomeryxf eight 

 species of pachyderms of the genera Hyopotamus, EMherium, Titanotherium, 

 Pakeochoc-rus, Leptochcerus, Hyracodon, and Rhinoceros; of soKpeds, a species 

 of Anchitherium; of rodents, four species of the genera Chalicomys, Ischy- 

 romys, Palaxdagus, and Eumys ; of carnivora, seven species of the genera 

 Hycenodon, Amphicyon, Drepanodon,^ and Deinictis ; and the turtle forms the 

 extinct genus Stylemys. 



From a later tertiary formation than the one just indicated, and suspected 

 to be of pleiocene age, on the Neobrara river, explored in the recent expe- 

 dition of Lieutenant G. K. Warren to Nebraska, Dr. Hayden, geologist to 

 the expedition, collected a large quantity of fossil bones. These are of 



1 The name Drepanodon was applied by Nesti, as early as 1826, to the sabre-tootlieil 

 tiger, for which, subsequently, a number of other names have been employed, that 

 of Macliairodus of Kamp being the most familiar. The author of the above remarks 

 applied the name Drepanodon, in 1856, to an extinct reptile or fish, a tooth of which 

 was discovered by Professor E. Emmoiis, at Cape Fear. X. C. The author would 

 iioxv substitute the r.ame JLetsticodut: hiijiar, Leidy, for the animal. 



