S30 Re2)orts and Proceedings — Geological Society of London. 



and the work throughout has been revised. A number of new 

 illustrations have been added, and among these are several very 

 elfective scenes reproduced from photograplis. 



As the author has remarked, while it is true that " geology cannot 

 be learnt from books," so it is equally true it " cannot be learnt 

 loiihotit books." It is difficult to convey any adequate idea of rocks, 

 especially eruptive rocks, from brief descriptions, and the same is 

 the case with minerals. The student should obtain examples of the 

 commoner rocks and minerals, and personally examine as many as 

 he can of the common and characteristic fossils. He or she will 

 then be able to make good progress with the help given by Mr. 

 Harrison, and it is noteworthy that his book has rendered much 

 service to those who have attended classes connected with the 

 Science and Art Department. Concise and systematic as this text- 

 book is, we can confidently recommend it as an excellent introduction 

 to geology. 



I^:H]:E=OI^TS .A.j<riD leiROGEiiBiDiisrcB-s. 



Geological Society of London. 



L — May 26, 1897. — Dr. Henry Hicks, F.R.S., President, in 

 the Chair. The following communications were read : — 



1. "On Augite-Diorites with Micropegmatite in Southern India." 

 By Thomas H. Holland, Esq., A.K.C.S., F.G.S., Officiating Super- 

 intendent, Geological Survey of India. 



This paper deals with a series of basic dykes intersecting the 

 pyroxene-granulites and gneisses of the Madras Presidency, and 

 believed to be of the same age as the lava-flows of the Cuddipah 

 system. These dykes consist essentially of augite (near heden- 

 bergite) and a plagioclase- felspar (near labradorite), between which 

 we find masses of micropegmatitic intergrowths of felspar and 

 quartz, with a micro-miarolitic structure. Around the patches of 

 micropegmatite, chemical changes have frequently taken place in 

 the minerals of the rock. Similar occurrences of micropegmatite 

 in basic rocks have been described by J. A. Phillips and Waller 

 at Penmaenmawr, by Hill and Bonney in Charnwood Forest, by 

 Teall in the Whin Sill and in the Cheviot district, by the last- 

 named author and Hai-ker at Carrock Fell, by Sollas at Carliugford, 

 and by Harker in Skye. 



After discussing the chemical constitution of the I'ock and of its 

 various constituents, and the relation between the micropegmatite 

 and the surrounding minerals, the author points out that three 

 methods for the formation of the micropegmatite may be con- 

 ceived of : — 



(a) During the primary consolidation of the magma. 



(/3) By secondary changes induced in the rock. 



(7) By subsequent intrusion of granophyric material into the 

 augite-plagioclase rock. 



In opposition to (7), the author points out the entire absence of 

 granitic intrusions in the neighbourhood. He regards the absence 



