VI. 



Oceanic Deposits Ancient and Modern. 



I. — The Foraminifera, 



RECENT deep-sea researches, by enabling us to understand more 

 fully the present distribution of the oceanic faunas, have revealed 

 many facts of the highest interest, and have supplied materials which 

 are invaluable to the stratigraphical geologist. In a recent paper,' 

 " The Genesis of the Chalk," I endeavoured to apply a few of these 

 results to a consideration of one of the great oceanic deposits of the 

 past, " the Chalk," and on this basis of comparison submitted con- 

 clusions of a definite character, both as regards the depth at which it 

 was formed and the general nature of its deposition. 



In an article {Science Progress, February number) Mr. Philip Lake 

 thus briefly summarises the main objections to the course adopted, 

 and says, " In questions of this kind, when the argument is based 

 upon the assumption that fossil forms lived and flourished under the 

 same conditions as their recent allies, it must always be borne in 

 mind that such an assumption is open to grave doubt. There is 

 nothing to prevent an animal from adapting itself to live under a new 

 set of conditions (for instance, at a different depth of the sea) without 

 becoming so much altered as to constitute a new genus." I have, 

 therefore, thought it would be interesting to examine the various 

 conditions step by step, to ascertain if the above objection is of 

 such vital importance that it must necessarily paralyse the whole 

 argument, and neutralise the method of research pursued. 



I. Faunal Distribution. — It will readily be admitted that any 

 genus (whether plant or animal) may adapt itself to a change of 

 condition without undergoing change of form. It may be even that 

 two such forms will alter their circumstances without metamorphosis 

 of type and character ; but if a whole group of organisms retains 

 precisely the same aspect throughout long ages, it may well be asked 

 whether similarity of conditions during long periods should not be 

 regarded as a determining factor in such a conservation of structure, 

 and whether, therefore, the onus of proving objections to suggestions 

 based on such identities should not lie with the objectors. 



If we take the Upper Cretaceous strata on the one hand, and 

 present deep-sea deposits on the other as principal terms of com- 



^ Proc. Geo!. Assoc, xiii., p. 221, May, 1894. 



