everywhere 39 deg. F. (4 deg. Cent.) is an error, which Dr. Wyville Thomson
adopted from eminent physical writers; but the general justice of the
reasoning is not affected by this circumstance, and Dr. Thomson's
expectation has been, to some extent, already verified.

Thus besides _Globigerina_, there are eighteen species of deep-sea
_Foraminifera_ identical with species found in the chalk. Imbedded in the
chalky mud of the deep sea, in many localities, are innumerable cup-
shaped sponges, provided with six-rayed silicious spicula, so disposed
that the wall of the cup is formed of a lacework of flinty thread. Not
less abundant, in some parts of the chalk formation, are the fossils
known as _Ventriculites_, well described by Dr. Thomson as "elegant vases
or cups, with branching root-like bases, or groups of regularly or
irregularly spreading tubes delicately fretted on the surface with an
impressed network like the finest lace"; and he adds, "When we compare
such recent forms as _Aphrocallistes, Iphiteon, Holtenia_, and
_Askonema_, with certain series of the chalk _Ventriculites_, there
cannot be the slightest doubt that they belong to the same family--in
some cases to very nearly allied genera."[9]

[Footnote 9: _The Depths of the Sea_, p. 484.]

Professor Duncan finds "several corals from the coast of Portugal more
nearly allied to chalk forms than to any others."

The Stalked Crinoids or Feather Stars, so abundant in ancient times, are
now exclusively confined to the deep sea, and the late explorations have
yielded forms of old affinity, the existence of which has hitherto been
unsuspected. The general character of the group of star fishes imbedded
in the white chalk is almost the same as in the modern Fauna of the deep
Atlantic. The sea urchins of the deep sea, while none of them are
specifically identical with any chalk form, belong to the same general
groups, and some closely approach extinct cretaceous genera.

Taking these facts in conjunction with the positive evidence of the
existence, during the Cretaceous epoch, of a deep ocean where now lies
the dry land of central and southern Europe, northern Africa, and western
and southern Asia; and of the gradual diminution of this ocean during the
older tertiary epoch, until it is represented at the present day by such
teacupfuls as the Caspian, the Black Sea, and the Mediterranean; the
supposition of Dr. Thomson and Dr. Carpenter that what is now the deep
Atlant