CONTENTS 



Page. 



Art. I. — A new Erian (Devonian) Plant allied to Cordaites; 



by Sir "Wm. Dawson 1 



II. — The Law of Thermal Radiation ; by Wm. Ferrel 3 



III.— Sti'atigraphic Position of the Olenellus Fauna in North 



America and Europe ; by C. D. Walcott 29 



IV. — Notes on the occurrence of a Leucite Rock in the Absa- 



roka Range, Wyoming Territory ; by A. Hague 43 



V. — On Allotropic Forms of Silver; by M. Caret Lea 47 



TVa. — The Peridotite of Pike County, Arkansas ; by J. C. 



Branner and R. N. Brackett. With Plate I 50 



VI.— On Urao ; by T. M. Chataed 59 



VII. — Notes on the Crystallization of Trona (TJrao) ; by E. 



F. Atres . . . . 65 



VIII. — On prevailing* misconceptions regarding the Evidence 



which we ought to expect of former Glacial Periods ; 



by J. Croll . 66 



IX. — Mineralogical Notes, on Fluorite, Opal, Amber and 



Diamond ; by G. F. Kttnz 72 



X. — Appendix. — Discovery of Cretaceous Mammalia; bv 



O. C. Marsh. With Plates II, III, IV, and V . 81 



SCIENTIFIC INTELLIGENCE. 



Chemistry and Physics. — On the action of Hydrogen peroxide on Chromic Acid, 

 Berthelot; On the Atomic Mass of Chromium, Rawson, 14. — On the new 

 Element Gnomium, Muller: Concentration of Electric Radiation by lenses, 

 Lodge and Howard: Wave-length of the principal line in the Spectrum of the 

 Aurora, Huggixs, 75. — Quartz as an insulator. Boys : Light and Magnetism, 

 S. Bidwell: Telephonic vibrations, Frohlich, 76. — On an Electrostatic Field 

 produced by varying Magnetic Induction, Lodge and Ohaltock, 77. 



Geology and Mineralogy. — Fossil Fishes and Fossil Plants of the Triassic Rocks of 

 New Jersey and the Connecticut Valley, J. S. Newberry, 77. — Map of the 

 rigion of Duck and Riding Mountains in Northwestern Manitoba, J. B. Tyr- 

 rell: Bulletin of the American Museum of Natural History, J. A. Allen anr 

 R. P. Whitfield, 78.— Plattnerite from Idaho, H. A. Wheeler, 79. 



Miscellaneous Scientific Intelligence. — Luminous night-clouds, 79. — American Asso- 

 ciation for the Advancement of Science : Sir Wm. Dawson on New Erian Plant, 

 80. 



