We have in this group a specimen of the track of a four-footed animal,
which may have been a frog, though different from ours. The feet are
unequal in size, and present a different number of toes. In existing
frogs there are four toes in the fore feet, and five in the hind; but,
in the specimen before us, the front toes are five in number, and the
back toes three. It is called, therefore, ANOMOEPUS, _unequal-footed_.
These impressions are in the red shale of Hadley, and very distinct.
In some of them the lower leg is indicated, forming an impression six
or seven inches long. The feet being smaller than the legs, the
impression made by the latter is more expanded, superficial, and
broader, yet still very definite. The opinion of President Hitchcock
and Dr. Deane is, that the different impressions of five and three
toes are those of the anterior and posterior extremities of one animal,
which, from the size of the limbs, might be a frog three feet high.
On the same schist with these footmarks, are other curious
impressions. The back of the slab is almost covered with the imprints
of rain-drops. In the midst of these is a tridactylous impression,
probably of a quadruped, crossed at its root by a single depression,
nearly an inch broad, and two and a half long: this seems to form part
of another broad superficial impression of about seven by four inches,
which is probably also quadrupedal. Other parts present the
impressions of nails and worm-tracks. At the opposite end is a deep,
smooth, regular excavation, which might have been made by a Medusa.
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