March. 1896. CORRESPONDENCE. 213 



noting the stations in their bathymetrical order, with the Foraminifera found at 

 them, and to my mind the conclusion is irresistible that the vast majority of the 

 arenaceous species and genera do not normally occur at depths beyond 400 or at 

 most 500 fathoms ; indeed it is a notable fact that, of the four examples quoted by my 

 critics from Australia and Ceylon, not a single one is outside the limits of terri- 

 genous deposits. When they inform us that 70 miles from Raine Island the 

 arenaceous species are ten in number at 790, and twenty at 985 fathoms, they quite 

 forget to mention that at Raine Island itself, at 155 fathoms, there are thirteen 

 genera and forty-six species, TexUdaria alone having over ten species to itself ! As 

 regards those cited from off the Coast of Africa, under the letters c, d, and e, it is 

 impossible to include these in this discussion, seeing that the authors give no details 

 whatever of the character and species of the Arenacea they state to have been 

 obtained there. 



The reason why the coarse Arenacea should occur within this limit is evident ; 

 their tests being made up of fine sandy materials, they will, for the most part, be 

 found where that material is most abundant, viz., within the area of the mud-zone. 

 Seeing, therefore, that oceanic slopes are usually very gradual, it is only, as a rule, 

 at a distance of about 200 miles from the coast that a 500-fathom limit would be 

 reached ; should, however, the slope be sudden, and the arenaceous material plenti- 

 ful, they will in that case, as the writers observe, be found at any depth ; but this, it 

 must be observed, must always be within the range of materials indispensable for 

 building up their shells. 



If my critics will carefully reconsider the quotations taken from my article on 

 pp. 273 and 274, they will probably admit that on two particular points they have 

 misinterpreted my meaning. In the one case they appear to infer that under the 

 term " coarse arenaceous Foraminifera " I include " all arenaceous Foraminifera " ; 

 and in the second case, quoting from p. 274, " Those species which are restricted to 

 the Chalk Marl, etc., are those which occurto-day at depthsof less than 400 fathoms," 

 they seem erroneously to have taken the word "occur" to be intended by me as 

 synonymous with "are restricted to." 



These points, I think, are of special importance in their argument, for, acting 

 under these assumptions, they proceed to deal with eleven species from different 

 pafts of my paper, all of which they erroneously commit me to have restricted to 

 a depth of 400 fathoms, and having thus proved to their own satisfaction that all 

 my premisses are wrong, they virtually assume that my suggested hypothesis is 

 baseless. 



Had Messrs. Burrows and Holland clearly understood my paper, it could 

 scarcely have escaped their notice that, on p. 274, referring to four of the species, 

 viz., Textiilaria agglutinans, Gaudryina piipoides, Haplophragmium latidorsatum, and 

 Ammodiscus incertus, I cite them as being particularly capable of deep-sea extension — 

 and why did I particularise this point"-? Certainly, it was with no intention what- 

 ever of demonstrating that my previous statements regarding distribution were 

 erroneous, but with the special object of showing that those forms which are 

 capable to-day of existing beyond the 500-fathom limit, and, as our authors say, 

 may go to any depth, are precisely those and only those which I have found to pass into 

 zones of the Chalk higher than those of the Lower Grey Chalk, and I therefore consider 

 them as strong evidence in favour of my hypothesis. 



Again, it is evident that, when in my paper I specially mention Culebra and 

 Raine Islands, I am referring to a geographical area which must equally embrace all 

 other localities possessing the same climatic and other conditions within that area, 

 therefore including New Guinea, Torres Straits, and the Arafura Sea. Of the 

 four species noted by me, Tritaxia tricarinaia, Spiroplecta annectens, Gaudryina rugosa, 

 and Frondkiilaria archiaciana , as occurring all together at Raine Island, the first is 

 known only there, the second occurs almost exclusively within that geographical 

 area, the third (as Mr. Chapman reminds me) is stated by Brady to have its finest 

 development at Raine Island, and the fourth has hitherto been discovered in no 

 other place, and I must re-emphasise my opinion that the association of these 

 forms, which are all typical Cretaceous ones, within a certain geographical area at 

 the present day is extremely suggestive to the student of physical conditions during 



