' Reviews — Dollfus's Geology. 619 



IV. — Guide to the Geology of London and the Neighbourhood. 

 By William Whitaker, B.A., F.G.S. 8vo. pp. 72. (Geological 

 Survey of England and Wales, London, 1875.) 



THIS little work is intended as an explanation of the Geological 

 Survey Map of London and its environs, which was noticed in 

 the Geological Magazine for May last, page 231 ; and also of the 

 Geological Model of London constructed under Mr. Whitaker's 

 superintendence (noticed in the Magazine for 1873, Vol. X. 

 page 513), and now exhibited in the Survey Museum. 



The work is confined to a general account of the geology, as 

 details have either been already published in Mr. Whitaker's large 

 memoir on the Geology of the London Basin, or will be given, so 

 he states, in a future memoir on the drifts of that area. 



The lithological features of the various formations are described ; 

 the leading fossils are mentioned; while the range, features, and 

 scenery, are also briefly noticed ; and lists of sections are given. 

 The work is written very concisely and systematically, and from the 

 number of interesting facts contained in it, it forms the best and 

 most useful summary of London geology that has been published. 

 It is probably the cheapest geological survey memoir for its size — 

 the price being one shilling ! — H. B. W. 



V. — Principes de Geologie Transformiste, Application de la 

 Theorie de l'Evolution a la Geologie. Par Gustave Dollfus. 

 8vo. pp. 178. (Paris : Librairie F. Savy.) 



AS may be seen from the title of this work, the endeavour of the 

 author is, to extend the theory of evolution, hitherto confined 

 to organic life alone, and to apply it to stratigraphical geology. 



This is not the first time that an attempt has been made to draw a 

 parallel between the organic and inorganic world, nor is it in any 

 way more successful than other such previous efforts. 



M. Dollfus commences by stating the opinions of, and quoting 

 from the most eminent geologists, past and present, with respect to 

 the fixity or non-fixity of species. 



In the second part, he briefly reviews each geological period, 

 giving and commenting on the various opinions held concerning 

 debated points; and especially remarking upon the modifications 

 which the several faunas undergo in their passage upwards. With 

 each formation is also given a table wherein the various beds of which 

 it is composed in the different countries of Western Europe are, as far 

 as possible, correlated. 



In the third part, under the heading " L'Espece en Stratigraphie," 

 the author expresses his idea more clearly. This seems to be, that 

 every bed, like an organized being, passes, so to speak, through 

 certain phases of existence. 



Its deposition is its birth, it then undergoes a series of meta- 

 morphoses until it reaches a stage in which it attains its full growth 

 and ceases to alter. Thus Lignite passes into Coal and then Graphite ; 

 Limestone into semi-crystalline Limestone and then into saccharoid 



