each vomer, at the fore part of both the outer and inner rows of the
smaller teeth in the upper jaw; and two or three similar tusks are
implanted, somewhat irregularly, behind the anterior extremity of
the series of smaller teeth in each ramus of the lower jaw. This
allocation of teeth in a double series on the premandibular bone is
peculiar, among Reptiles, to the Cecilia and the present almost equally
aberrant form of Batrachian. It is a common dental character in
the class of fishes, and its repetition in the Labyrinthodon betrays a
tendency to the ichthyic type which is manifested by some other
of the extinct reptiles, as the Ichthyosaurus, although this genus in
its general organization is essentially related to a higher order than
that to which the Labyrinthodon belongs.
The first discovered fossils belonging to this genus were certain
detached teeth from the Keuper sandstone (Alaunschiefer) of Wirtem-
herg, of which the largest is figured at PL 63, fig. 1 , from the “ Fossile
Reptilien in Wurtemberg,” 4to. 1828-, of Prof. Jaeger, by whom the
name Mastodonsaurus was applied to these teeth under the impression
that they were the remains of some gigantic Saurian reptile. (1)
Other fossil fragments of jaws and teeth, or casts of teeth, also
from the Keuper formation, (Dolomitsandstein), on which Prof.
Jaeger has founded his genus Phytosaurus, I believe to belong to the
same genus and most probably to the same species as the preceding
teeth. The most remarkable of these fossils is described as the
palatal ourface of the upper jaw, measuring one foot and a half in
length, nine inches in breadth at the posterior part and between two
and three inches across the narrower anterior part of the fragment.
On one side of this fragment there was a series of twenty-seven, and
probably of thirty sockets, with very narrow and not quite equal interspaces.
The anterior portion containing eighteen of these serial
sockets, and probably the fractured bases of the teeth, is copied from
Prof. Jaeger’s work, at PI. 63, fig. 3. At a short, distance anterior to
the series of smaller teeth, there is a portion of the socket, a, or 1
(1) The genus Mastodonsaurus is placed in the Saurian system of M. Hermann v. Meyer,
m the Crocodilian family, intermediate between Steneosaurus or Macrospondylus and Crocodilus :
the species on which the genus is founded is termed, after its discoverer, Mastodonsaurus Jae-
geri. Palseologica, 8vo. 1832, p. 107.
cavity for the reception of one of the great tusks. The tooth, indicated
by the letter b, is described as exhibiting a pulp-cavity, and the adjoining
tooth, c, as showing a new tooth rising into the pulp-cavity,
in progress of displacing the old tooth, after the manner of succession
in the teeth of the crocodile. PI. 63, figs. 2 and 4, represent
the fossils on which Prof. Jaeger has founded respectively his
species denominated Phytosaurus cubicodon and Phytosaurus cylindri-
codon, but it is doubtful whether they are teeth or casts of the sockets of
most probably conical teeth, of which they exhibit only the shape
of the implanted base: the real teeth that have been discovered
in the same quarry as that which yielded the preceding casts have
the form represented in fig. 5: these, like the teeth of Mastodonsaurus
Jaegeri, are conical and are marked by fine striae extending
from the base to the middle of the crown : they hear the same relative
proportions to the large tusk (PI. 63, fig. 1) as do the serial teeth
of the British species of Labyrinthodon to their anterior tusks. (1)
A third remarkable and characteristic fossil discovered in the
Keuper sandstone (alaunschiefer) and described by Prof. Jaeger, (loc.
cit. p. 38, pi. v, figs. 1 and 2), consists of the occipital portion of the
cranium with two large and separate condyles, as in the batrachian
reptiles: on this fossil the Professor founded his species called “ Sala-
mandroides giganteus.”(2) Now the teeth of the extinct Batrachians
from the New-Red Sandstone in Warwickshire correspond with
those of the so-called Mastodonsaurus, in presenting a highly characteristic
and peculiar structure (PL 64 b , fig. 2), which has
suggested for the genus to which they belong the name of Labyrinthodon
: and as the great teeth of the so called Mastodonsaurus
correspond in size with the cranial fragment with the batrachian
condyles above mentioned, it is highly probable that they belong
to the same species of reptile as that fragment. But it is certain
that the teeth of this gigantic Keuper reptile belong
(1) The genus Phytosaurus in the Saurian system of H. von Meyer is placed between
Mosasaurus and Saurocephalus. I have already proved the latter to belong to the class of fishes,
and, if the Phytosaurus be identical with Mastodonsaurus, they must both be expunged from
the Saurian order.
(2) The Salamandrdides giganteus of Jaeger, is placed in the system of H. von Meyer, between
the Salamandra gigantea and the Triton noachicus, in the order Batrachia: it belongs, however,
to a distinct family in that order.