Clarksville weekly chronicle. (Clarksville, Tenn.) 1873-1890, 1879-08-23
The Cabinets of the University.
(CONTINUED.)

CONTINUED
The types of life in this mid-era
of the world, approach the modern
to certain extent particularly is
this the case in the later portion of
it, the Cretaceous Period. 1t is in
deed a transition time, the old
forms dying out, and more familiar
features being gradually assumed.
Some of the life remains are very
beautiful. Here is d large collection
of most exquisite Pentacrinite
stems, perfectly pentagonal, and
their surfaces richly marked they
would please the eye of the most
Indifferent observer. These speci-
mems are from Germany and the
United States. There are also two
splendid representatives of Encri-
nus LilifOrmis from Solenhofen.
\ neighboring drawer contains
one hundred Belemnites, another
characteristic type. Their form is
that of pointed cone, from one to
four inches in length, resembling
considerably cigar. This is a very
interesting FOssil-it is the internal
bone of an ancient Cuttle-fish, the
analogue of the so-called Pen-and-
Ink fish, frequently obtained from
the Atlantic. 1t is, however, not a
fish, but a MOllusk a naked Cepha-
lopod, of high organization. 1t
contains an ink-bag within cavity
of this bone, the black contents OF
which it squirts forth behind it
when necessity demands, in order
that it may thereby elude its pur-
suer. This ink-bag containing the
black pigment has often been found
in fossil state. The name of this
fossil is from belemnon, meaning
a dart.
But we pass on to another Cepha-
lopOd form, which is also very
distinguishing feature of this age
the Ammonite, successor to the
OrthOceras and the Goniate of the
Paleozoic, and a congener of the
modern Nautilus. 1t is character
| lied as Il close coiled chambered
shell, the septa being very elabOr-
ately frilled, the external portion of
the shell highly ribbed and Orna-
lnented; and the siphuncle (the
tube by which communication is
kept up between the outer chamber
and the inner apartmenD dOrsal.
A beautiful specimen is here seen,
from Oberstein, Germany, cut
through perpendicularly to the
septa, the surface of section being
polished. The inner arrangement
is splendidly represented, the ma
terial of the partition walls having
been substituted, in the process of
petrifaction, by Iron pyrites, while
the chambers have been filed in
with Calcite and in some cases with
Red Oxide of Iron, thus most hand
somely mapping out the boundaries
of the original structure. The spec
linens of AmmOnites are from Ger
many, France, England and the
United States. These typical close
coiled Ammonites were succeeded
in the Cretaceous Period by more or
less uncoiled varieties-we have
here representatives of Faculties,
Hamites, Scaphites- huge frag
ment of q huge Ancyloceras from
England is very noticeable.
Among Lamellibranchs, we find
some handsome representatives
the three sided bivalve, Trigonia,
with its ornamental lines of tuber-
cles, is present in specimens from
England; as also from this country.
The Oyster family is here intro
duced in the shape of the genus
Gryphea, some species of which are
quite attractive. The EXogyra,
also, is anearly related form. Ostrea
too, has a number of very quaint
looking specimens, the edges of
whose valves are deeply but rather
regularly dentated, giving to it a
unique appearance. Several varie-
ties of Sponge are here. Sponges
were very numerous during the
Cretaceous, their siliceous spicuIes
being supposed to have furnished
the material of the Flints of the
Chalk beds.
Besides the Crinoids already men
toned, and indeed entirely spp-
planting them towards the close of
the age, we have many free Echi-
noids, as Cidaris Blumenbachii,
several species of Ananchites, Con
faster, etc. These forms are very
numerous, handsome and quite
modern in look. Vertebrates are
represented by a specimen of Lep-
tolepis from Solenhofen, besides
teeth of fishes and reptiles-and not
least, two fine impressions on the
Red Sandstone of the Connecticut
River Valley, the so-called bird
tracks. They are three-toed, and
about four inches in length.
These are the most characteristic
Fossils of this very interesting geo.
logical age. There are many others
well worthy of description, which
we leave unnamed; we now come
to the survey of forms of life be-
longing to the Cenozoic Time, which |
are much more familiar to the eye |
than those already noticed, being
nearly related to the existing
regime; they in consequence, need I
but little at our hands.
During the Tertiary Age, a grow !
ing resemblance is to be seen, to the
now existing forms. Although the
species in general differ from those I
of our own day, there is not suffi-
cient dissimilarity to render them