806 



SCIENCE. 



FN. S. Vol. 711. No. 180. 



concei-ning certain beds of this stage, that '"be- 

 tween Briiun and Olmutz (in Moravia) there 

 exists a large number of these outliers in the 

 form of isolated buttes, of which the upper pla. 

 teau, formed of limestone with Lithothamnium^ 

 attains very uniformly the altitude of from 350 

 to 356 meters. Nevertheless at Ruditz, not far 

 from Briinn, this formation occurs as high up as 

 435 meters, and at an elevation of 429 meters at 

 Abtsdorf, towards the bottom of the great gulf of 

 Bohemia. If we assume, as Suess does, that 

 broad sheets of flat strata cannot have been ele- 

 vated to their position, they must have been de- 

 posited at that or a higher level. Hence, the 

 adjacent lower lying deposits of the same stage, 

 together with the sea-level, have been depressed. 



Two chapters are devoted to the great desert 

 plateau of the Sahara and to the fragments of 

 the Indian continent, or Gondwana-land. The 

 lands of these areas are held to be the oldest in 

 the eastern hemisphere. The geological knowl- 

 edge concerning this district is fairly well sum- 

 marized, the faults and evidences of change of 

 level by displacement being particularly set 

 forth. In the sequel of this work Suess prom- 

 ises to consider whether the sinking of continents 

 so vast as the lost areas of Gondwana-land has 

 been able to produce a general lowering of the 

 shore-lines and so determine the emergence of 

 plateaus like that of Sahara and Arabia. 



Two long chapters are devoted to a descrip- 

 tion of the mountain chains of India and Cen- 

 tral Asia, presenting a good summarj'' of the 

 geology of these regions. North and South 

 America then come in for discussion and com- 

 parison with typical Alpine areas. Concerning 

 the earthquakes of the South American coast, 

 Suess holds them to be ' the index of some great 

 tectonic phenomenon of the present epoch, the 

 nature of which is unknown.' 



Closing the first volume is a chapter on The 

 Continents. Our author, admitting the diffi- 

 culty which arises in deciding upon characters 

 which should be accepted in defining the age of 

 a continent, thinks it best to fix its birth ' from 

 the time when the sea has definitely abandoned 

 the large depressions in its area. ' In this light 

 North America is held to be no older than the 

 Laramie. In this same point of view, Gond- 

 wana-land is much older than America. 



Many interesting questions, which the above 

 outline of Suess's views will raise in the mind 

 of the physical geologist, will best be deferred 

 for discussion in connection with the promised 

 second volume of the work, in which it is 

 understood they are to be treated by the 

 author himself. 



The first volume is accompanied by a list of 

 contents and is well printed. The pages bris- 

 tle with footnotes and bibliographic references, 

 the larger part of which are due to the compre- 

 hensive grasp of the current literature of geol- 

 ogy which M. De Margerie has more than once 

 displayed. As a key to the geology of a large 

 part of the globe the book is invaluable on this 

 account alone. The illustrations are few in 

 number, but good. Many points in the distri- 

 bution of geological formations on which the 

 argument so often depends might be made 

 clearer to a large class of students by the addi- 

 tion of a few more maps. An atlas as detailed 

 as Stieler's Hand- Atlas is really necessary for 

 following some of the descriptions in an intel- 

 ligent way. While one closes the book with- 

 out being convinced that the author's point of 

 view and his interpretation of certain fields are 

 necessarily the only or the right ones, he does so 

 with a feeling of renewed interest in the geology 

 of large areas and in the great physical prob- 

 lems of the earth. Every advanced geological 

 student should read the book for information, 

 for suggestion, for a broadening of his view and 

 to see how a master in the art of writing mar- 

 shals facts from one of the widest and most 

 varied fields of natural science. 



J. B. WOODWOETH. 



A Classified Catalogue, with Localities, of the Land 



Shells of America, North of Mexico. By H. 



A. PiLSBEY. Philadelphia, April, 1898. 



Pp. 35. 



The appearance of a new catalogue of North 

 American land mollusca is a matter of interest, 

 not merely to malacologists, but to all students 

 of geographical distribution. Mainly through 

 the efforts of Mr. Pilsbry, our snails have been 

 newly classified in recent years, more nearly in 

 accordance with their relationships than here- 

 tofore. At the same time, the genera have been 

 divided into subgenera and sections, while 



