CONTENTS. 



PAGE 



I. Researches on the Hexntomic Compounds of Cobalt. By 



WOLCOTT GiBBS, M.D 1 



TI. Contributions to the Botany of North America. By Asa 

 Gray : — 



1. Synopsis of North American Thistles 39 



2. Notes on Borrac/inacece 48 



3. Synopsis of North American Species of Phy salts . 62 



4. Characters of various Neiv Species 68 



III. Graphical Integration. By Edward C. Pickering . . 79 



IV. On the Solar Motion in Space. By Truman Henry 



Safford 82 



V. Historical Sketch of the Generic Names proposed for Butter- 

 flies: A Contribution to Systematic Nomenclature. By 

 Samuel H. Scudder 91 



VI. On the Wide Diffusion of Vanadium and its Association tcith 



Phosphorus in many Rocks. By A. A. Hayes, M.D. . 291 



Vn. Contributions from the Physical Laboratory of the Mas- 

 sachusetts Institute of Teclmology: — 



1. Foci of Lenses placed Obliquely. By Prof. E. C. 



Pickering and Dr. Chas. H. Williams . . 300 



VIII. Brief Contributions from the Physical Laboratory of Har- 

 vard College : — 



1. On the Effect of Heat upon the Magnetic Suscepti- 

 bility of Soft Iron. By H. Amory and F. Minot 308 



IX. A Conspectus of the North American Ilydrophyllacece. By 



Asa Gray 312 



X. Revision of the Genus Ceanothus, and Descriptions of New 

 Plants, with a Synopsis of the Western Species of Silene. 

 By ,Sereno Watson 333 



XI. List of the Marine Algce of the United States, with Notes of 



New and Imperfectly Known Species. By W. G. Farlow 351 



