Geological Society. 147 



will alone decide whether it is to hold the place in the theory of 

 these twins which vom Rath assigns to it. 



The book is an inestimable boon to the student, who will find in 

 it a store of information. Unfortunately one trifling matter — a 

 legacy from Prof. Miller — will much interfere with its success as 

 a text-book, and will, we fear, at no distant future necessitate a 

 new edition and modification of many of the beautiful diagrams of 

 crystal forms with which it is bountifully supplied. This misfor- 

 tune arises from the orientation of the axes of X and Y. All 

 Continental and American writers have long adopted one in which 

 Miller's orientation is inverted. And the amount of literature in 

 which this inverted arrangement is used is now so great that it is 

 hopeless to expect ever to change it. It is a trifle in itself, but 

 anyone familiar with the liability to error in changing a notation, 

 and the confusion which a slight error in notation introduces, will 

 recognize its force. To a student, however, who is not troubling 

 himself with the literature of minerals, it will cause little incon- 

 venience in the use of the book. 



It would be difficult to praise too highly the printing, and more 

 especially the illustrations, of the book. A better illustrated book 

 on crystallography has, we think, never been published. 



VIII. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 



[Continued from vol. xxxix. p. 547.] 



January 9th, 1895. — Dr. Henry Woodward, F.R.S., President* 



in the Chair. 



THE following communications were read : — 

 1. * The Formation of Oolite.' By E. B. Wethered, Esq., F.G.S. 



2. ' On the Lias Ironstone aronnd Banbury.' By Edwin A. 

 Walford, Esq., F.G.S. 



The ferruginous limestone of the Middle Lias of the Banbury 

 district occurs practically within a ten-mile circle around Banbury. 

 The stone (the Marlstone of the Geological Survey) is an 'oolitic' 

 cyprid-limestone with much molluscan and crinoidal debris and some 

 quartz-grains. The author describes the lithological characters of 

 the rock, and their variations, as traced laterally and vertically, 

 giving a full description of its local development, with a detailed 

 account of the sections in the principal exposures. The marlstone 

 of this area is dissimilar from that of Gloucestershire both in 

 appearance and in fossil contents, the Gloucestershire stone being of 

 earlier deposition and representing better the baseof the Banbury 

 series, rather than the stratum which is richest in iron. From the 

 blue clays of the Margaritatus-zone up to the rock-bed itself there 

 is a slow change of conditions, and the fauna points to tranquil 



