ical periods, the quaternary, tertiary, and secondary formations,
contain organisms which still live. It is more probable, in the
proportion of 3 to 1, that the transition or primary period is not
different, but that it is only more difficult to examine and understand,
by reason of the gradual and prolonged chemical decomposition and
metamorphosis of many of its organic constituents."

"10. By the mass-forming _Infasoria_ and _Polythalamia_, secondary are
not distinguishable from tertiary formations; and, from what has been
said, it is possible that, at this very day, rock masses are forming in
the sea, and being raised by volcanic agencies, the constitution of
which, on the whole, is altogether similar to that of the chalk. The
chalk remains distinguishable by its organic remains as a formation, but
not as a kind of rock."]

Ehrenberg appears to have taken it for granted that the _Globigerinoe_
and other _Foraminifera_ which are found in the deep-sea mud, live at the
great depths in which their remains are found; and he supports this
opinion by producing evidence that the soft parts of these organisms are
preserved, and may be demonstrated by removing the calcareous matter with
dilute acids. In 1857, the evidence for and against this conclusion
appeared to me to be insufficient to warrant a positive conclusion one
way or the other, and I expressed myself in my report to the Admiralty on
Captain Dayman's soundings in the following terms:--

"When we consider the immense area over which this deposit is spread, the
depth at which its formation is going on, and its similarity to chalk,
and still more to such rocks as the marls of Caltanisetta, the question,
whence are all these organisms derived? becomes one of high scientific
interest.

"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