ecimens; the tracks have the same general
character with the preceding, but are smaller.

The third species of this genus is styled the BRONTOZOUM LOXONYX,
from _loxos_, a _bow_, and _onyx_, a _nail_,--a curved nail. It is
smaller than the Sillimanium, and has the nail set to one side.

The fourth species, still smaller, is the Brontozoum Gracillimum. On
this slab the impressions are in relief; viz.: 1st, of Brontozoum
Gracillimum; 2d, of Brontozoum Parallelum; 3d, of the track of a
tortoise, fourteen inches long, and two wide. Other extensive
eminences and depressions, with rain-drops, may be observed on the
same surface.

The fifth species is called BRONTOZOUM PARALLELUM, from the tracks
being on a line with each other. Of this there are two specimens, one
of them, however, being a single track. On the surface of the other
slab there are at least five distinct tracks, one of them being a
small new and undescribed species,--thus making the whole number of
species of Brontozoum which we possess to be at least six.

The SECOND GENUS of Struthiones is called _AEthyopus_, from
_aithuia_, a _gull_, and _pous_, a _foot_,--gull-footed. This genus
is smaller than the Brontozoum Giganteum; and we have two species,
viz. the AETHYOPUS LYELLIANUS, which is the larger, and two specimens
of AETHYOPUS MINOR. All of these are distinguished from the preceding
genus by the winged foot, and in the Lyellianus by the shallowness of
the impression. The AEthyopus Minor is not always distinguished by the
superficiality of its impression. This is sometimes deep. Therefore
this character may not be considered a distinctive one, or the
AEthyopus Minor might be referred to another genus. Of the two
specimens of this latter species, the first is in depression,
tridactylous. The depressions are deep with rain-drops, marks of
quadrupeds and zoophytes over the whole surface. The ornithichnic
impressions are two in number; one superficial, the other very deep.
The reversed surface of this slab contains one tridactylous impression
in relief. The second specimen has three depressions; two of which are
superficial, and the third is quite deep, displaying, by a depressed
surface, the webbed character of the foot.

* * * * *

GROUP SECOND.

We shall take, to characterize this group, the _Argozoum_, from
_arges_, _swift_, _winged_.

Of this genus there are two species, the larger of which