Reviews — Prof. Gaudry — Philosophical Palaeontology. 429 



general change in the river system is that the crest of the Alps has 

 retreated northwards. The southern slope being much steeper than 

 that to the north, the Italian rivers have more power of erosion than 

 their northern rivals, and are gradually eating their way back. The 

 Upper Engadine is a conspicuous example. 



" Many minor changes have taken place : partly (1) through recent 

 changes of level, as, for instance, that which has diverted the Reuss 

 from its old course by the Lake of Zug, and driven it round by 

 Lucerne ; partly (2) by rival rivers deepening and extending their 

 valleys, and thus annexing territory which previously belonged to 

 others ; for instance, the Landquart has robbed the Landwasser of 

 its head waters and carried off the Schlappina, the Vereina, and the 

 Sardasca ; partly (3) by dams due to river cones or glacial moraines, 

 as, for instance, the Limmat, which was driven from the Glatthal and 

 the Sihl from the Valley of the Lake of Zurich. 



"The lakes'which contribute so much to the beauty of the country 

 fall into several different categories. 



" 1. Some are due to the inequalities in the glacial deposits ; as the 

 numerous small pieces of water in the curious district of the Pays 

 de Dombes. 



" 2. Some are due to subsidence ; strata, generally those of 

 gypsum or salt, having been dissolved and removed; as, for instance, 

 the lakes of Cadagno and Tremorgia. 



" 3. Some are dammed back by river cones, as the lakes of the 

 Upper Engadine; or by moraines, as the lakes of Sempach, Baldeggar, 

 and Hallwyl. 



" 4. The origin of the larger Swiss lakes has been the subject of 

 much discussion. The opinion now prevalent among Swiss geologists 

 is that they are mainly due to recent changes of level, and are in 

 fact drowned river valleys. 



"Even more striking than the exquisite beauty of the lakes is the 

 grandeur of the history they unfold, and of the causes to which they 

 are due ; and, indeed, in contemplating the geueral scenery of 

 Switzerland, we cannot but be profoundly impressed by the enormous 

 magnitude of the changes, and the irresistible forces which have 

 been brought into operation." 



We have been tempted to quote perhaps too largely from this very 

 interesting summary. To those who are attracted by this notice 

 we would say, "Get the book and read it for yourselves." It is just 

 of a handy size to put into one's haversack and take as a iiseful 

 companion to Switzerland. The illustrations are very numerous, 

 and many of them are excellent from a geologist's point of view. 



II. — Essai de Paleontologie Phieosophique. By Professor 

 Albert Gaudry, Meinb. Inst. France, For. Memb. Geol. Soc. 

 London. Paris, 1896. (Dulau and Co., London.) 



n^HIS volume forms a supplement to the distinguished author's 

 I well-known work "Enchainements du Monde Animal dans les 



Temps Geologiques " : in it the facts and arguments brought forward 



in his previous volumes are correlated, and an attempt is made to 



