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interrupted at long intervals by periods of repose. But we
must now return to Port St. Julian. On the south side of
the harbour, a cliff of about ninety feet in height intersects
a plain constituted of the formations above described; and
its surface is strewed over with recent marine shells. The
gravel, however, differently from that in every other locality,
is covered by a very irregular and thin bed of a reddish loam,
containing a few small calcareous concretions. The matter
somewhat resembles that of the Pampas, and probably owes
its origin either to a small stream having formerly entered
the sea at that spot, or to a mud-bank similar to those now
existing at the head of the harbour. In one spot this
earthy matter filled up a hollow, or gully, worn quite through
the gravel, and in this mass a group of large bones was
embedded. The animal to which they belonged, must
have lived, as in the case at Bahia Blanca, at a period long
subsequent to the existence of the shells now inhabiting the
coast. We may feel sure of this, because the formation of
the lower terrace or plain, must necessarily have been
posterior to those above it, and on the surface of the two
higher ones, sea-shells of recent species are scattered. From
the small physical change, which the last one hundred feet elevation
of the continent could have produced, the climate, as
well as the general condition of Patagonia, probably was nearly
the same, at the time when the animal was embedded, as it now
is. This conclusion is moreover supported by the identity of
the shells belonging to the two ages. Then immediately
occurred the difficulty, how could any large quadruped have
subsisted on these wretched deserts in lat. 49° 15'? I had
no idea at the time, to what kind of animal these remains
belonged. The puzzle, however, was soon solved when
Mr. Owen examined them; for he considers that they
formed part of an animal allied to the guanaco or llama, but
fully as large as the true camel. As all the existing members
of the family of Camelidie are inhabitants of the most sterile
countries, so may we suppose was this extinct kind. The
structure of the cervical vertebra;, the transverse processes
L I
not being perforated for the vertebral artery, indicates its
affinity: some other parts, however, of its structure, probably
are anomalous.
The most important result of this discovery, is the confirmation
of the law that existing animals have a close
relation in form with extinct species. As the guanaco is the
characteristic quadruped of Patagonia, and the vicuna of the
snow-clad summits of the Cordillera, so in bygone days,
this gigantic species of the same family must have been conspicuous
on the southern plains. We see this same relation
of type between the existing and fossil Ctenomys, between
the capybara (but less plainly, as shown by Mr. Owen) and
the gigantic Toxodon; and lastly, between the living and
extinct Edentata. At the present day, in South America,
there exist probably nineteen species of this order, distributed
into several genera; while throughout the rest of
the world there are but five. If, then, there is a relation
between the living and the dead, we should expect that the
Edentata would be numerous in the fossil state. I need
only reply by enumerating the megatherium, and the three
or four other great species, discovered at Bahia Blanca;
the remains of some of which are also abundant over the whole
immense territory of La Plata. I have already pointed out
the singular relation between the armadilloes and their great
prototypes, even in a point apparently of so little importance
as their external covering.
The order of rodents at the present day, is most conspicuous
in South America, on account of the vast number*
and size of the species, and the multitude of individuals:
according to the same law, we should expect to find their
representatives in a fossil state. Mr. Owen has shown how-
far the Toxodon is thus related; and it is moreover not
* I n ray co lle c tio n M r. W a te rh o u s e d istin g u ish e s tw e n ty -s e v e n sp e c ie s
o f m ice ; to th e s e m u s t b e a d d e d a b o u t th ir te e n m o re , k n ow n from th e
w o rk s o f A z a ra , a n d o th e r n a tu r a lis ts ; so t h a t w e h a v e fo rty sp e cie s,
w h ic h h a v e a c tu a lly b e e n d e s c rib ed a s c om in g from b e tw e e n th e T ro p ic
a n d C a p e H o rn .
VOL. in . 1’