472 Reviews — Prof. L. O. de Koninck — 



interested in this branch of geology, especially as regards the author's 

 view of volcanic fusion. 



After alluding to the various hypotheses on this subject, the 

 author says : — " Suppose above the temperature of fusion is a column 

 of thirty miles of rock, and suppose three miles are rapidly removed 

 by erosion. The position of the couche of temperature of fusion 

 will constantly tend to retire towards the centre of the earth. If it 

 retires at the same rate as erosion, the effect of pressure on the 

 couche of the temperature of fusion will remain the same ; but if 

 the rate of erosion and consequent removal of pressure is greater 

 than that of the recession of the couche of temperature, plus that of 

 general secular recession, the effect, it would seem, must be to create 

 a local fusion." 



The orography of the region forms the subject of the eighth 

 chapter, and is further explained by five coloured maps, showing 

 the exposures of successive orographic disturbances ; of these — " the 

 post-Carboniferous, post-Jurassic, post-Cretaceous — taken together — 

 were the main building-times of the modern American continent, 

 and each of these orographical disturbances were most violent at 

 the western edge of the region involved" (p. 759). 



The limited space at our disposal prevents us from entering 

 into more details of the contents of this suggestive work, which the 

 reader must consult for himself in order to fully appreciate its 

 nature as a piece of connected history, bearing in mind, however, 

 " that it is not a geological survey, but a rapid exploration of a very 

 great area, in which literally nothing but a few isolated details was 

 befoi'e known. It is an attempt to read the geology of the Middle 

 Cordilleras, and to present the leading outlines of one of the most 

 impressive sections of the earth's surface film." 



For our own part we fully recognize, after perusing this work, not 

 only the arduous labours of Clarence King and his colleagues during 

 their ten years' exploration in the field, but, also, the instructive and 

 systematic manner in which some of the most striking geological 

 and physical features of the region are recorded, as further illustrated 

 in the twenty-eight beautiful plates and the twelve analytical geolo- 

 gical maps, interspersed throughout the 800 pages of letterpress. 



J. M. 



II. — Faune du Calcaike Carbonifere de la Belgiqtje. Par L. 

 G. de Koninck. Folio, pp. 132. Atlas 31 Planches. (F. 

 Hayez: Bruxelles, 1878.) 



IF ANY apology were needed for the appearance of this valuable 

 addition to palasontological literature, that offered by the dis- 

 tinguished author as the raison d'etre of this initial volume of a 

 series to be devoted to the fauna of the Carboniferous Limestone of 

 Belgium is surely a most valid one. In 1842 Professor de Koninck, 

 in a somewhat similar work, raised the number of known species 

 from two hundred to nearly five hundred described forms. At the 

 present time, however, more than double that number, or from one 

 thousand to twelve hundred species, from that horizon, are contained 



