iv CONTENTS. 
XIV. On the Mode of Formation of the Tails of Comets; by ee 
Prof. Wittiam A. Norton, - 104 
XV. Reply to Mr. Couthouy’s Vindication 2 against ihe’ bideges 
of Plagiarism; by Jam—esD.Dana, - - -~ = 
XVI. Account of some new Infusorial Forms discovered in the 
Fossil Infusoria from Petersburg, Va., and Piscataway, 
Md. ; by Prof. J. W. Bamtry,—(with a plate,) - = - 
XVII. Tesice of the New York Geological Reports, -» - 148 
XVIII. The Variation and Dip of the Magnetic Needle at Nan oe 
tucket, Mass.; by Winuiam MircHert, - - 157 
XIX. eo acttatis of Microlite and Chas maa by Agath 
tus A. Hayes, - 158 ‘ 
XX. On the A state of Columbic Acid e Thais A. ‘fone 166 © 
XXI. Hints on the Iceberg Theory of Drift ;—in a letter from 
Mr. Perer Dosson to Prof. Epwarp Hircucock, - 1} 
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. Forses, F. R.S., &c., 172 
XXIII. Bibliographical Notices :—Reliquie Baldwinianz : selec- 
tions from the correspondence of the late Wm. Baldwin, 
M. D., 192.—Jussieu’s Cours élémentaire 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 Encyclopedia 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- 
hecticut, 205.—Method of separating the Oxides of Cerium 
and Didymium, 206.—Sillimanite and Monazite, 207.—The 
