148). So like were these impressions
to the shape of the human hand, that the at that time unknown
animal which produced them was at once christened _Cheirotherium_,
or "Hand-beast." Further discoveries, however, soon showed that
the footprints of _Cheirotherium_ were really produced by species
of Amphibians which, like the existing Frogs, possessed hind-feet
of a much larger size than the fore-feet, and to which the name
of _Labyrinthodonts_ was applied in consequence of the complex
microscopic structure of the teeth (fig. 149). In the essential
details of their structure, the Triassic Labyrinthodonts did not
differ materially from their predecessors in the Coal-measures
and Permian rocks. They possessed the same frog-like skulls (fig.
150), with a lizard-like body, a long tail, and comparatively
feeble limbs. The hind-limbs were stronger and longer than the
fore-limbs, and the lower surface of the body was protected by an
armour of bony plates. Some of the Triassic Labyrinthodonts must
have attained dimensions utterly unapproached amongst existing
Amphibians, the skull of _Labyrinthodon Joegeri_ (fig. 150) being
upwards of three feet in length and two feet in breadth. Restorations
of some of these extraordinary creatures have been attempted in
the guise of colossal Frogs; but they must in reality have more
closely resembled huge Newts.
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