40 Reviews — A. cle Grossouvre on the Upper Chalk. 



upon this subject, some considering the Chalk to be a deep-water 

 pelagic deposit, and others maintaining that it was formed in 

 comparatively shallow water and not far from land. He constructs 

 a table of the successive kinds of deposit which would normally be 

 formed in an area which underwent extensive subsidence until it was 

 covered by very deep water and then slowly rose again, and he 

 shows that Cretaceous deposits found in the Paris Basin correspond 

 with such a succession, that each stage indicates deeper water than 

 that below, till in the Chalk with many flints we have a deposit 

 formed in water of more than 500 metres and at a great distance 

 from shore-lines. 



He next examines the minute structure of Chalk, the Chalk fauna, 

 and the composition of flints, quoting the opinions and observations 

 of many authors. He concludes that white chalk must have been 

 deposited in the central parts of a very extensive sea, the deepest 

 part of which may have been about 1,000 metres (546 fathoms). 



Chapter iv is M. Lambert's essay on the genus Micraster, but 

 it is not easy to see why this should have been included in these 

 volumes, which are described as the stratigraphical part of a more 

 complete treatise. Moreover, since M. de Grossouvre relies mainly 

 on Ammonites for his zonal classification one would have expected 

 an essay on them rather than one on the Micrasters. 



M. Lambert enumerates a large number of species, and considers 

 between 30 and 40 of them to be good species, though not all of 

 these occur in the Anglo-Parisian basin. He describes the species 

 in the order of their creation, and not in the order of their affinities. 

 He does not indicate the characters which he considers to be of 

 specific importance, but seems to rely mainly on differences in 

 general shape, in the characters of the ambulacral areas, and in the 

 clearness of the subanal fasciole. He does not recognize the 

 importance of the peristome, the labral plate, the tip of the labrum, 

 and the periplastronal area, on each of which Dr. Rowe lays stress. 



The general classification of the Upper Cretaceous Series occupies 

 a long chapter. A preliminary discussion of principles leads the 

 author to take D'Orbigny's names for his primary divisions or stages, 

 and ho also adopts most of Coquand's sub-stages, finally indicating 

 what zones he would include in these several sub-stages. The indices 

 of his zones are throughout species of Ammonites, and he expressly 

 states that if Echinids were taken as guides the zones would not be 

 the same. 



Dealing first with the Cenomanian, he has necessarily to fix the 

 limits of the stage, and more especially its lower limit. This, as he 

 remarks, is a question which has often been debated, and which has 

 recently been the subject of controversy between mj^^self and 

 M. G. Dollfus. After reviewing the difficulties the author decides 

 in favour of the view which I have maintained ; he puts aside the 

 argument of the Cenomanian transgression as valueless, and while 

 admitting that there are some localities v\rhere beds of passage exist 

 and where " hesitation is admissible," he continues : " but this is not 

 the case in the north of France, and if as a basis of classification 



