burg.
The footprints of a large quadruped, probably batrachian, had also been
observed by Dr. King in the carboniferous rocks of Pennsylvania in 1844.
The first example of the _bones_ of a reptile in the Coal of North
America was detected so lately as September, 1852, by Mr. G. W. Dawson
and myself in Nova Scotia. These remains, referred by Messrs. Wyman and
Owen to a perennibranchiate batrachian, were met with in the interior of
an erect fossil tree, apparently a sigillaria. They seem clearly to have
been introduced together with sediment into the tree, during its
submergence and after it had decayed and was standing as a hollow
cylinder of bark, this bark being now converted into coal.

When Agassiz, in his great work on fossil fish, described 152 species of
ichthyolites from the Coal, he found them to consist of 94 placoids,
belonging to the families of shark and ray, and 58 ganoids. One family
of the latter he called "sauroid fish," including the megalicthys and
holoptychius, often of great size, and all predaceous. Although true
fish, and not intermediate between that class and reptiles, they seem to
have been more highly organized than any living fish, reminding us of
the skeletons of saurians by the close suture of their cranial bones,
their large conical teeth, striated longitudinally, and the articulation
of the spinous processes with the vertebrae. Among living species they
are most nearly allied to the lepidosteus, or bony pike of the North
American rivers. Before the recent progress of discovery above alluded
to had shown the fallacy of such ideas, it was imagined by some
geologists that this ichthyic type was the more highly developed,
because it took the lead at the head of nature before the class of
reptiles had been created. The confident assumption indulged in till the
year 1844, that reptiles were first introduced into the earth in the
Permian period, shows the danger of taking for granted that the date of
the creation of any family of animals or plants in past time coincides
with the age of the oldest stratified rock in which the geologist has
detected its remains. Nevertheless, after repeated disappointments, we
find some naturalists as much disposed as ever to rely on such negative
evidence, and to feel now as sure that reptiles were not introduced into
the earth till after the Silurian epoch, as they were in 1844, that they
appeared for the first time at an era subsequent to the carboniferous.

Sc