Xll 



EXPLANATION OF THE PLATES. 



Platfs Page 



fPROTOCONCHS OF TbAGOBHILLOCERAS LOSCOMBI ',\ 



Shells of the same, and Sutures at various j 

 diameters ; and Sutures, Radial Lines, etc. j 

 XLVIII-L-{ of certain Ammonites for comparison with )■ 336 

 Tkagophyllocebas loscojibi, illustrating Mr. ! 

 L. F. Spath's paper on the Development of I 

 ^ the above-mentioned Ammonite J 



LI & LII <J 



/'Quartz-Topaz Vein in Quarry C, and 'Reaction- 

 Border' of Schorl-Rock shown in the same 

 quarry: and Microscope-Sections of Igneous 



I 



Rocks from Gunong Bakap, illustrating Mr. 

 J. B. Scrivenor's paper on the Topaz-bearing 

 Rocks of that locality 



y 3G3 



/'Diagram showing the Chemical Composition of 

 the Lavas and the Molecular Proportions 

 of Tiie Oxides in the Series of Rocks ; and 

 Diagram showing the Specific Gravities and 

 LIII&LIV-{ Variation-Diagram of the Molecular Pro- 

 portions of the Metallic Oxides compared 

 with Silica, illustrating Prof. P. Marshall's 

 paper on the Sequence of Lavas at the North 



{ Head, Omgo Harbour 



Y 382 



; 



Folding-plate (facing p. xc): Profiles 

 Rivers Exe, Medway, and Severn. 

 Presidential Address. 



showing Gradients of the 

 illustrating Dr. A. Strahan's 



