214 NATURAL SCIENCE. March, 



the Chalk period. The fact that Spivoplecta annectens has been found at greater 

 depths is not in any way surprising, for, far from being a coarse-grained type, it is 

 one of the most delicate of all the Arenacea. 



One word upon their closing remarks, vol. viii., p. 104. " In reference to the question 

 of the depth at which the Taplow Chalk was probably laid down, Mr. Hume places 

 great stress upon the occurrence together at Culebra Island of Vevncuilina pygmaa, et 

 seq." This statement is liable to mislead, seeing that I made no reference whatever 

 as to the depth at which the Taplow Chalk was deposited. I only mentioned these 

 species in association with others as additional evidence of the importance of 

 Culebra Island from a Cretaceous point of view, and, as a matter of fact, there are 

 at least thirty-two forms in actual existence there capable of being directly com- 

 pared with Cretaceous types ; but I expressly left them out of the discussion, seeing 

 that a number of them might be considered as pelagic. 



In studying the Foraminifera, I think it may be advisable to lay stress upon the 

 fact that, in the present state of our knowledge of their animal structure, it is im- 

 possible to attach particular importance to " genera " and " species." These terms 

 have been employed by me, as by all those who are interested in these fascinating 

 little tests, to indicate forms, often of most beautiful and definite construction, but, 

 nevertheless, throwing but little light on the nature of the organisms that con- 

 structed them. It is a presumption, and a fair one, that similar results have been 

 produced under similar conditions ; it is also admissible to assume that the animals 

 constructing them at the present day are similar to, if not identical with, their 

 prototypes of the Cretaceous period. 



I have desired in my paper to refrain entirely from anything approaching 

 dogmatism. My research has been merely carried out on these lines in the hope 

 that some light may be thrown on a path which, at present, is very obscure. This, 

 so far as it has gone, tends to show that, whatever the conditions may be now, they 

 were, in Cretaceous times, running on parallel lines to those existing in certain areas 

 at the present day, and my aim will have been attained if my researches should lead 

 others to consider, without prejudice or factiousness, the problems underlying the 

 ancient and modern faunal distribution. ,y P ttj,^,„ 



With reference to the foregoing remarks of Dr. Hume upon our criticism of the 

 evidence from the Foraminifera adduced by him in his paper on " Oceanic Deposits 

 Ancient and Modern," we have to say : — 



1. As we were careful to explain, we refrained altogether from discussing the 

 main hypothesis propounded by Dr. Hume. We simply ventured to question the 

 evidence as to the distribution of certain Foraminifera in recent seas which the 

 writer brought forward in support of his argument. 



2. Dr. Hume objects that, in quoting from his paper the passage — " at the 

 present day the coarse arenaceous Foraminifera are found at depths rarely exceed- 

 ing 400 fathoms" — without giving the context, we have been unfair to him. We 

 have again read over his paper, and we cannot see that it contains anything to show 

 that the words we quoted were not intended to be taken as the expression of a 

 general law. We find nothing to imply that at the present day the coarse Arenacea 

 are to be met with, at all commonly, at depths beyond 400 fathoms. Now, doubtless. 

 Dr. Hume has modified, to some extent, his former statement ; but, if so unneces- 

 sary to the argument, why was a 400-fathom limit mentioned at all ? In point of 

 fact, however, anyone reading together Dr. Hame's papers on " The Genesis of the 

 Chalk " and " Oceanic Deposits Ancient and Modern " must see that considerable 

 importance was attached to this limit of 400 fathoms. 



3. We were quite alive to the fact that Dr. Hume laid stress upon the 

 association of certain forms — notably three species of TexiiUiyia and three species of 

 Verneuilina ; and we put forward considerations tending, as we think, to show that 

 such weight as the writer attached to this association could not properly be con- 

 ceded. We cannot see that his further remarks make the argument from the 

 association of so small a number of such protean forms as the Foraminifera any 

 stronger. The associated forms occur as independent individuals ; they do not 

 make up a kind of zoological compound ; and when it is shown — to take the three 



