IV CONTENTS. 



» 



Number* 2. 



Page 

 Art. VII. — The Cretaceous Armored Dinosaur, Nodosaurus 



textilis Marsh; by R. S. Lull (With Plates I to lY) . . 97 



Art. VIII. — Outline of the Applimtion of the Theory of Space 

 Groups to the Study of the Structure of Crystals; by R. 

 W. G. Wyckoff \ 127 



Art. IX. — Crystal Structure of Magnesium Oxide; by R. W. 



G. Wyckoff 138 



Art. X. — Mississippian Formations of the Ilorton-Windsor 



District, Nova Scotia; by W. A. Bkll loo 



Art, XI. — Relations of Subjacent Igneous Invasion to Re- 

 gional Metamorphism (continued); by J. Barrell 174 



Art. XII. — Permian of Coahuila, ISTorthern Mexico; by E. 



BosE 187 



Art. XIII. — Occurrence of Structures like Walcott's Algon- ■ 

 kian Algne in the Permian of England ; by O. IIoltedahl li)5 



SCIENTIFIC INTELLIGENCE. 



Chemistry and P/i//su'.s— Perchloric Acid as a Dehydrating Agent in the Deter- 

 mination of Silica, H. H. Willard and W. E. Coke : Chemistry and 

 Crystallography of Some Fluorides of Cobalt, Nickel, Manganese and 

 Copijer, F. H. Edjiister and H. C. Cooper, 207. — Notes on Chemical Be- 

 search, W. P. Dreaper : Elementary Chemistry for Coal-mining Students ; 

 L. T. O'Shea. 208.— Creative Chemistry, E. E. Slosson : (Xi en est La 

 Meteorologie, A. Berget, 209. — Etude sur Le Systeme Solaire, P. Reynaud, 

 210.— The National Physical Laboratory, Report for the Year 1919, 211. 



Geology and Mineralogy— Geo\ogj of Anglesey, E Greenly, 212.— Abriss der 

 Allgemeinen und Stratigraphischen Geologie, E. Kayser : Geology and 

 Mineral Resources of Bexar Co.. Texas, E. H. Sellards: Geology of Tarrant 

 County, W. M. Winton and W. S. Adkins : Mineralogy, an Introduction 

 to the Study of Minerals and Crystals, E. H. Kraus and VV. F. Hunt, 

 218.— Ore Deposits of Utah, B. S. Butler, 214. 



Obituary — H. A. BuiMstead : W. deW. Abney : P. S. Umfreville : W. A. 

 Howard : Y. Delage, 214. 



