“Three answers have suggested themselves:—­

“In accordance with the prevalent view of the limitation of life to comparatively small depths, it is imagined either:  1, that these organisms have drifted into their present position from shallower waters; or 2, that they habitually live at the surface of the ocean, and only fall down into their present position.

“1.  I conceive that the first supposition is negatived by the extremely marked zoological peculiarity of the deep-sea fauna.

“Had the Globigerinoe been drifted into their present position from shallow water, we should find a very large proportion of the characteristic inhabitants of shallow waters mixed with them, and this would the more certainly be the case, as the large Globigerinoe, so abundant in the deep-sea soundings, are, in proportion to their size, more solid and massive than almost any other Foraminifera.  But the fact is that the proportion of other Foraminifera is exceedingly small, nor have I found as yet, in the deep-sea deposits, any such matters as fragments of molluscous shells, of Echini, &c., which abound in shallow waters, and are quite as likely to be drifted as the heavy Globigerinoe.  Again, the relative proportions of young and fully formed Globigerinoe seem inconsistent with the notion that they have travelled far.  And it seems difficult to imagine why, had the deposit been accumulated in this way, Coscinodisci should so almost entirely represent the Diatomaceoe.

“2.  The second hypothesis is far more feasible, and is strongly supported by the fact that many Polycistineoe [Radiolaria] and Coscinodisci are well known to live at the surface of the ocean.  Mr. Macdonald, Assistant-Surgeon of H.M.S. Herald, now in the South-Western Pacific, has lately sent home some very valuable observations on living forms of this kind, met with in the stomachs of oceanic mollusks, and therefore certainly inhabitants of the superficial layer of the ocean.  But it is a singular circumstance that only one of the forms figured by Mr. Macdonald is at all like a Globigerina, and there are some peculiarities about even this which make me greatly doubt its affinity with that genus.  The form, indeed, is not unlike that of a Globigerina, but it is provided with long radiating processes, of which I have never seen any trace in Globigerina.  Did they exist, they might explain what otherwise is a great objection to this view, viz., how is it conceivable that the heavy Globigerina should maintain itself at the surface of the water?

“If the organic bodies in the deep-sea soundings have neither been drifted, nor have fallen from above, there remains but one alternative—­ they must have lived and died where they are.

“Important objections, however, at once suggest themselves to this view.  How can animal life be conceived to exist under such conditions of light, temperature, pressure, and aeration as must obtain at these vast depths?