CONTENTS. XXI 



PAGE 



XVIII. Notes on the Anatomy of the Genus Firola. By John Denis 

 Macdonald, R.N., F.R.S., Surgeon of H.M.S. " Icarus." Com- 

 municated by Professor Maclagan. (With a Plate, IX. fig. 4), 189 



XIX. On the Structure and Optical Phenomena of Ancient Decomposed 

 Glass. By Sir David Brewster, K.H., D.C.L., F.R.S., &c. 

 (With two Plates, X., XI.), . . . .193 



XX. On the Polarisation of Light by Rough and White Surfaces. By Sir 



David Brewster, K.H., D.C.L., F.R.S., &c., . . 205 



XXI. Observations on the Polarisation of the Atmosphere., made at St 

 Andrews in 1841, 1842, 1843, 1844, and 1845. By Sir David 

 Brewster, K.H,, D.C.L., F.R.S., &c. (With a Plate, XII.), 211 



XXII. On a Pre-Brachial Stage in the Development of Comatula, and its 

 importance in relation to certain Aberrant Forms of Extinct 

 Crinoids. By Professor Allman. (With a Plate, XIII.), . 241 



XXIII. Some Account of the Recent Progress of Sanskrit Studies. By J. 



MuiR, D.C.L., LL.D., 253 



XXIV. On Fagnani's Theorem. By H. F. Talbot, Esq., . . 285 



XXV. On the Influence of Weather upon Disease and Mortality . By R. E. 

 ScoRESBY- Jackson, M.D., F.R.S.E., F.R.C.P., Lecturer on Ma- 

 teria Medica and Therapeutics at Surgeons' Hall, Edin- 

 burgh. (With Five Plates, XIV.-XVIII.), . . .299 



XXVI. On the Anatomical Type of Structure of the Human Umbilical Cord 

 and Placenta. By J. Y. Simpson, M.D., Professor of Medicine 

 and, Midwifery in the University of Edinburgh, , . 349 



XXVII. On Earth-Currents during Magnetic Calms., and their connection with 



Magnetic Changes. By Balfour Stewart, M.A., F.R.S., . 355 



XXVIII. On the Great Refracting Telescope at Elchies, in Morayshire, and 



its Powers in Sidereal Observation. By Professor C. Piazzi 

 Smyth, ....... 371 



VOL. XXIII. PART III. f 



