68 NATURAL SCIENCE. Jan., 



the natural history of successive periods ; but from this broad point 

 of view all sorts and conditions of life and of land and water would 

 have to be considered. 



In the present work the author endeavours to picture the changes 

 in the distribution of land and water, over the area now occupied by 

 the British Islands, during each of tlie great epochs of time which 

 make up our geological sequence. His task is a most difficult one, 

 for few geologists have been tempted to draw boundary-lines to mark 

 the former limits of formations, however well they may be acquainted 

 with them. It is one thing to picture in the imagination former 

 general geological conditions ; it is quite another thing to draw the 

 outlines of land and water and to fill in conjectural rivers and lakes. 

 The subject, like discussions on theology, is apt to lead to almost 

 endless diversity of opinion, for (as the author admits) the materials 

 for forming a definite judgment are so imperfect. 



That his work is appreciated, is shown by the issue of a second 

 edition, in which the author has added over a hundred pages of 

 further information. Altogether there are fifteen plates drawn to show 

 the geography of different epochs. Three of these 'are new, six 

 remain the same as in the first edition, and six have been subject to 

 alteration. Several other small maps and sections are printed with 

 the text. One of the principal alterations is in the map of the 

 Ordovician period (Arenig Epoch) ; we notice also that a small lake 

 is introduced into the Devonshire and Cornish area, in the map that 

 represents the Permian period. 



Whatever value the maps may possess, there can be no doubt 

 that the author has brought together, in a most painstaking way, a 

 large amount of material bearing on the physical geography of our 

 bygone ages. He concludes with a chapter on the Supposed Per- 

 manence of Continents and Oceans, and with an appendix on the 

 Sub-oceanic Crust. 



LeS ALPES pRANCpAIS, LES MONTAGNES, LES EaUX, LES GlACIERS, LES PhENO- 



MENEs DE l' Atmosphere. [Bibliotheque Scientifique Contemporaine.] By 

 Albert Falsan. Pp. 288. Illustrated. Paris : J. B. Bailliere et Fils, 1893. 

 Price 3fr. 50c. 



In a little volume of 280 pages, Monsieur Falsan has given a readable 

 account of the French Alps, their geology, physical geography, and 

 meteorology. The author's extensive experience and well-known 

 writings will attest his competence to speak on the subject, and we 

 need only add that the condensation from larger works has been 

 carefully and judiciously made. The nature of Monsieur Falsan's 

 special studies leads to marked prominence being given to the glaciers 

 and ancient glacial phenomena, and to the Tertiary geology of the 

 Alps. The chapters on these subjects are particularly good, and to 

 them the geologist will naturally turn. 



A Catalogue of British Jurassic Gasteropoda. By W. H. Hudleston, F.R.S., 

 and Edward Wilson, F.G.S. Pp. xxxiv., 148. London : Dulau and Co., 1892. 

 Price 7s. 6d. 



This work, although it embraces a comparatively small section of 

 our British Fossils, is a most important addition to that series which 

 we hope will eventually replace the famous Morris' Catalogue. Nearly 

 forty years ha\e elapsed since the second edition of Morris' work was 

 published. In that volume only five species of Gasteropoda are 



