lk, and the characters
of its dental apparatus indicate that it was much more peaceful
in its habits than its associates the Nothosaur and Simosaur.

[Illustration: Fig. 153.--Under surface of the upper jaw and palate
of _Placodus gigas_. Muschelkalk, Germany.]

The Triassic rocks of South Africa and India have yielded the
remains of some extraordinary Reptiles, which have been placed by
Professor Owen in a separate order under the name of _Anomodontia_.
The two principal genera of this group are _Dicynodon_ and
_Oudenodon_, both of which appear to have been large Reptiles,
with well-developed limbs, organised for progression upon the
dry land. In _Oudenodon_ (fig. 154, B) the jaws seem to have
been wholly destitute of teeth, and must have been encased in
a horny sheath, similar to that with which we are familiar in
the beak of a Turtle. In _Dicynodon_ (fig. 154, A), on the other
hand, the front of the upper jaw and the whole of the lower jaw
were destitute of teeth, and the front of the mouth must have
constituted a kind of beak; but the upper jaw possessed on each
side a single huge conical tusk, which is directed downwards,
and must have continued to grow during the life of the animal.

[Illustration: Fig. 154.--Triassic Anomodont Reptiles. A, Skull
of _Dicynodon lacerticeps_, showing one of the great maxillary
tusks; B, Skull of _Oudenodon Bainii_, showing the toothless,
beak-like jaws. From the Trias of South Africa. (After Owen.)]

It may be mentioned that the above-mentioned Triassic sandstones
of South Africa have recently yielded to the researches of Professor
Owen a new and unexpected type of Reptile, which exhibits some
of the structural peculiarities which we have been accustomed
to regard as characteristic of the Carnivorous quadrupeds. The
Reptile in question has been named _Cyanodraco_, and it is looked
upon by its distinguished discoverer as the type of a new order,
to which he has given the name of _Theriodontia_. The teeth of
this singular form agree with those of the Carnivorous quadrupeds
in consisting of three distinct groups--namely, front teeth or
_incisors_, eye teeth or _canines_, and back teeth or _molars_.
The canines also are long and pointed, very much compressed, and
having their lateral margins finely serrated, thus presenting a
singular resemblance to the teeth of the extinct "Sabre-toothed
Tiger" (_Machairodus_). The bone of the upper arm (humerus) further
shows some remarkable res