740 report— 1884. 



many countries, it would be rash in the extreme to infer the synchronism of portions 

 of these when separated by degrees of latitude. The time required for these zones 

 to travel from Kent to the Crimea, and to accumulate a mass, mainly composed 

 of minute organisms, of over a thousand feet in thickness, must have been sufficient 

 to account for a very sensible progress in the evolution of organic forms. 



The deposition of the Chalk commenced in the English area at a period when 

 the land floras were still of Jurassic character. By the time it had reached 

 Limburg, Saxony, and Bohemia, Dicotyledons had become developed. The period 

 required for the chalk ocean to encroach but 300 to 400 miles must thus have been 

 very vast. The question may however arise, whether plant development at this 

 stage followed the otherwise universal law of evolution, or was exceptionally rapid. 

 The fauna has to be examined to see whether it discloses an equally appreciable 

 progress. The conclusion arrived at is, that while the groups with which the 

 author is less acquainted apparently do so, the progress in the Mollusca is unmis- 

 takable. The helicoid, turbinate, and patelloid groups are archaic and stationary, but 

 the fusiform shells betray a tendency to elongate their canals, and the relative 

 abundance of such, and gradual dropping out of now extinct genera, furnish an 

 unmistakable index of the relative ages of the more littoral deposits. From this 

 point of view we are able to demonstrate that the Greensands of Aix-la-Chapelle 

 are far younger than their lithological structure and sequence would indicate, 

 while the appearance of such distinctly new developments as cone and cowry shells 

 further support the views of the relatively almost tertiary, or, at least, transition 

 age of the Cretaceous series in Denmark. While, therefore, denudation on a truly 

 colossal scale has produced one of the most considerable gaps in the whole 

 geological record between Cretaceous and Tertiary over the British area, beds of 

 intermediate age may successfully be sought for at a distance from this centre. 

 The erroneous correlation of these, bed by bed almost, with the typical Cretaceous 

 series, as developed in England, has led to a still more untrustworthy correlation of 

 the American series with ours. 



The Cretaceous series of America contains at its very base a flora composed of 

 angiosperms so perfectly differentiated that they are apparently referable to existing 

 genera. One of the oldest floras in Europe containing angiosperms is that of 

 Aix-la-Chapelle, and even this we have seen is relatively modern : but these are 

 not referable in at all an equal degree to existing genera, and even the Coniferae 

 are embarrassing on account of their highly transitional characters. The oldest 

 Cretaceous flora of America, so far from possessing any Cretaceous characters, 

 agrees in a remarkable manner with that of the English Lower Eocene, while the 

 Laramie, or supposed Cretaceo-Eocene, flora has very much in common with that 

 of our Middle Eocene, and marks a similarly sudden rise in temperature. The 

 question is whether the evidence of the fauna in favour of the Cretaceous age 

 of the series is so conclusive that the floral evidence must be set aside. Taking 

 the Cretaceous series as represented in California, the older stages possess Mollusca of 

 definitely Cretaceous aspect, hut those of the newest have a decidedly Eocene facies. 

 To be Cretaceous a fauna must have some elements which did not survive to a later 

 period ; but are we in a position to state that the Ammonitidas, the Belemnites, 

 and Inocerami did not do so ? Even our present limited knowledge is entirely 

 opposed to such a view. It must be remembered that the Eocenes in their typical 

 area, England and France, were deposited under peculiar local conditions, and it 

 would be as logical to infer from the absence in them of Cretaceous types that 

 these existed nowhere else, as it would be, were the bed of the English Channel 

 now upheaved, to class as extinct all forms of life not met with in its sands and 

 muds. If, as there is evidence to show, America was isolated at the time, the 

 survival there of forms of Reptilia, elsewhere extinct, would be in accordance with 

 ordinary observation at the present day. 



The flora of the American series is Eocene ; the fauna of its earlier stages is 

 Cretaceous. We are compelled, therefore, to choose whether we will believe that 

 a large Eocene flora was developed there during the Cretaceous, or that some 

 members of a Cretaceous fauna lived on to an Eocene date. The former supposition 

 demands greater rapidity of evolution than we are accustomed to admit, and no 



