CONTENTS. VII 



Number 35. 



Page 



Art. XXXV. — Irregular Reflection; by C. C. Hutchins.. 373 



XXXVI. — Occurrence of Sperrylite in North Carolina; by 



W. E. Hidden 381 



XXXVII. — Description of a Fauna found in the Devonian 



Black Shale of Eastern Kentucky; by G. H. Girty 384 



XXXVIII. — Separation of Nickel and Cobalt by Hydro- 

 chloric Acid; by F. S. Havens 396 



XXXIX. — Contributions to Paleontology ; by F. A. Lucas 399 



XL. — Value of Type Specimens and Importance of their 



Preservation ; by O. C. Marsh 401 



XLI. — Origin of Mammals ; by O. C. Marsh 406 



XLII. — Causes of Variation in the Composition of Igneous 



Rocks; by T. L. Walker 410 



XLIII. — Relation between Structural and Magneto-optic Ro- 

 tation ; by A. W. Wright and D. A. Kreider 416 



SCIENTIFIC INTELLIGENCE. 



Chemistry and Physics— Crystallized Metallic Calcium, Moissan: Preparation 

 and Properties of Calcium Hydride, Moissax, 428.— Improved method for 

 determining Molecular Mass by the Boiling Point, Walker aod Ltjmsden, 429. 

 — Chemical Effects of the Silent Electric Discharge, Berthelot, 430. — New 

 Gas, C. E. Brush, 431. — Electricity and Magnetism: a Mathematical Treatise 

 for advanced undergraduate students. F. E. Nipher: Electrical currents ex- 

 cited by Rontgen rays, A. Winkelmann, 432.— Reflection of Cathode rays, H. 

 Starke. Change of the energy of Cathode rays into light rays, E. Wiedemann : 

 Theory of the Coherer, D. van Gulik and E. Dorn: Absorption of light pro- 

 duced by a body placed in a magnetic field, A. Right, 433. 



Geology and Mineralogy— Eighteenth Annual Report of the Director of the U. S. 

 Geological Survey, 1896-7, 433.— Summary Report of the Geological Depart- 

 ment of Canada for ihe year 1897, 434. — Geological History of the Isthmus of 

 Panama and portions of Costa Rica, R. T. Hill: Physical geography of Wor- 

 cester, Mass., J. H. Perry: Handbuch der Mineralogie, C. Hintze, 435.— 

 Manual of Determinative Mineralogy with an Introduction on Blowpipe Analy- 

 sis, G. J. Brush and S. L. Penfield : Law of Mines and Mining in the United 

 States, D. M. Barringer and J. S. Adams, 436.— Canadian minerals, G. C. 

 Hoffmann, 437. 



Obituary— James Hall, 437. 



