ra bear to certain of the fern family. In at least two
species of Pterophyllum,--_P. comptum_ and _P. minus_,--the divisions of
the leaflets seem little else than accidental rents in a simple frond;
in _P. Nelsoni_ they are apparently _nothing_ more; and similar
divisions, evidently, however, the effect of accident, and less rounded
at their extremities than in at least _P. comptum_, we find exhibited by
some of the Helmsdale specimens of Taeniopteris (See Fig. 142, p. 488.)
But whatever the nature of these simple fronds, they seem to impart much
of its peculiar character, all the world over, to the flora of the
Oolitic ages.

[Illustration: Fig. 143.

PECOPTERIS OBTUSIFOLIA.]

[Illustration: Fig. 144.]

[Illustration: Fig. 145.

PACHYPTERIS.]

The compound ferns of the formation are numerous, and at least
proportionally a considerable part of them seem identical in species
with those of the Oolite of England. (See Fig. 143.) Among these there
occur _Pecopteris Whitbiensis_, _Pecopteris obtusifolia_, _Pecopteris
insignis_,--all well marked English species; with several others. It
has, besides, its apparent ferns, that seem to be new--(Fig. 144)--that
are at least not figured in any of the fossil floras to which I have
access,--(Fig. 145),--such as a well defined Pachypteris, with leaflets
broader and rounder than the typical _P. lanceolata_, and a much stouter
midrib; a minute Sphenopteris too, and what seems to be a Phlebopteris,
somewhat resembling _P. propinqua_, but greatly more massive in its
general proportions. The equisetacea we find represented in the Brora
deposits by _Equisetum columnare_,--a plant the broken remains of which
occur in great abundance, and which, as was remarked by our President
many years ago, in his paper on the Sutherlandshire Oolite, must have
entered largely into the composition of the bed of lignite known as the
Brora Coal. We find associated with it what seems to be the last of the
Calamites,--_Calamites arenaceus_,--a name, however, which seems to have
been bestowed both on this Oolitic plant and a resembling Carboniferous
species. The deposit has also its Lycopodites, though, from their
resemblance in foliage to the conifers, there exists that difficulty in
drawing the line between them to which I have already adverted. One of
these, however, so exactly resembles a lycopodite of both the Virginian
and Yorkshire Oolite,--_L. uncifolius_,--that I cannot avoid regarding
it as spe