XI 1 CONTENTS. 



Page 



No. III. EXTRACTS from LETTERS to PROFESSOR FORBES, on 

 the Analogy of the Structure of some Volcanic Rocks 

 with that of Glaciers. By C. DARWIN, Esq., F.R.S.* 266 



No. IV. ACCOUNT OF AN EXPERIMENT ON STOCKHOLM PITCH, 



CONFIRMING THE VlSCOUS THEORY OF GLACIERS. In 



a Letter from PROFESSOR GORDON of Glasgow to PRO- 

 FESSOR J. D. FORBES of Edinburgh* . . . 269 



No. V. EXTRACTS from a LETTER from E. BLACKWELL, Esq., 

 containing Observations on the Movement of Gla- 

 ciers of Chamouni in Winter, with remarks by PRO- 

 FESSOR FORBES 271 



* These articles ought chronologically to have preceded the two first of the 

 Appendix ; they ought also to have been referred to at pages 92, 201, and 215. 



ERRATA. 



Page 80, line 6 from bottom, for Plate II. read Plate I. 

 119, line 1, for XIV. read XIII. 



