idering how large a surface these bodies expose in proportion
to their weight, it is probable that they occupy a great length of time
in making their burial journey from the surface of the Atlantic to the
bottom.

But if the Radiolaria and Diatoms are thus rained upon the bottom of the
sea, from the superficial layer of its waters in which they pass their
lives, it is obviously possible that the Globigerinae may be similarly
derived; and if they were so, it would be much more easy to
understand how they obtain their supply of food than it is at present.
Nevertheless, the positive and negative evidence all points the other
way. The skeletons of the full-grown, deep-sea Globigerinae are so
remarkably solid and heavy in proportion to their surface as to seem
little fitted for floating; and, as a matter of fact, they are not to be
found along with the Diatoms and Radiolaria, in the uppermost stratum of
the open ocean.

It has been observed, again, that the abundance of Globigerinae, in
proportion to other organisms, of like kind, increases with the depth
of the sea; and that deep-water Globigerinae are larger than those
which live in shallower parts of the sea; and such facts negative the
supposition that these organisms have been swept by currents from the
shallows into the deeps of the Atlantic.

It therefore seems to be hardly doubtful that these wonderful creatures
live and die at the depths in which they are found.

However, the important points for us are, that the living Globigerinae
are exclusively marine animals, the skeletons of which abound at the
bottom of deep seas; and that there is not a shadow of reason for
believing that the habits of the Globigerinae of the chalk differed from
those of the existing species. But if this be true, there is no escaping
the conclusion that the chalk itself is the dried mud of an ancient deep
sea.

In working over the soundings collected by Captain Dayman, I was
surprised to find that many of what I have called the "granules" of that
mud, were not, as one might have been tempted to think at first, the
mere powder and waste of Globigerinae, but that they had a definite form
and size. I termed these bodies "coccoliths," and doubted their
organic nature. Dr. Wallich [65] verified my observation, and added the
interesting discovery, that, not unfrequently, bodies similar to these
"coccoliths" were aggregated together into spheroids, which he termed
"coccospheres." So far as we