IV CONTENTS. 



Page. 



XIV. On the Mode of Formation of the Tails of Comets ; by 



Prof. William A. Norton, 104 



XV. Reply to Mr. Couthouy's Vindication against the charge 



of Plagiarism ; by James D. Dana, .... 129 



XVI. Account of some new Infusorial Forms discovered in the 

 Fossil Infusoria from Petersburg, Va., and Piscataway, 

 Md. ; by Prof. J. W. Bailey,— (with a plate,) - - 137 

 XVII. Review of the New York Geological Reports, - - 143 

 XVIII. The Variation and Dip of the Magnetic Needle at Nan- 

 tucket, Mass. ; by William Mitchell, ... 157 



XIX. Re-examination of Microlite and Pyrochlore ; by Augus- 

 tus A. Hayes, 158 



XX. On the A state of Columbic Acid ; by Augustus A. Hayes, 166 



XXI. Hints on the Iceberg Theory of Drift ; — in a letter from 



Mr. Peter Dobson to Prof. Edward Hitchcock, - 169 

 XXII. Notice of Travels in the Alps of Savoy, and other parts 

 of the Pennine Chain, with observations on the phenom- 

 ena of Glaciers; by James D. Forbes, F. R. S., &c, 172 

 XXIII. Bibliographical Notices : — Reliquise Baldwinianse : selec- 

 tions from the correspondence of the late Wm. Baldwin, 

 M. D., 192. — Jussieu's Cours elementaire de Botanique, 

 195. — Endlicher's Grundzuge der Botanik : BischofF's 

 Lehrbuch der Botanik, 196. — Fresenius's Grundriss der 

 Botanik, zum Gebrauche bei seinen Vorlesungen : Buek's 

 Index generalis et specialis ad A. P. De Candolle Prodro- 

 mum Syst. Nat. Reg. Vegetabilis, &c, 197. — Ledebour's 

 Flora Rossica : Babington's Manual of British Botany,' 

 198. — Kunze's Supplemente der Reidgraser, 199. — Bo- 

 tanische Zeitung : Prof. Forbes's Bakerian Lecture, 

 200. — Memoirs of the Chemical Society of London, 201. 

 — The Encyclopaedia of Chemistry, Theoretical and 

 Practical, 202. — Mr. Alger's edition of Allan's Phillips' 

 Mineralogy : Proceedings of the Boston Society of Nat- 

 ural History, 203. — Proceedings of the American Philo- 

 sophical Society, 204. — Sketch of the Analytical Engine 

 invented by Charles Babbage, Esq., 205. 



Miscellanies. — Dr. Percival, the original observer of the crescent- 

 formed Dykes of Trap in the New Red Sandstone of Con- 

 necticut, 205. — Method of separating the Oxides of Cerium 

 and Didymium, 206. — Sillimanite and Monazite, 207. — The 



