nt the leaflets of one of our commonest
Aspleniums,--_Asplenium trichomanes_. One of our highest authorities,
however, in such matters (Professor Balfour of Edinburgh) questions
whether this organism be in reality a fern, and describes it from the
specimen on the table, in the Palaeontological chapter of his admirable
Class Book, simply as "a remarkable pinnate frond." (Fig. 13, p. 56.) We
find it associated with the remains of a terrestrial plant allied to
lepidodendron, and which in size and general appearance not a little
resembles one of our commonest club mosses,--_Lycopodium clavatum_.[48]
It sends out its branches in exactly the same style,--some short and
simple, others branched like the parent stem,--in an arrangement
approximately alternate; and is everywhere covered, stem and branch, by
thickly set scale-like leaflets, that, suddenly narrowing, terminate in
exceedingly slim points. It has, however, proportionally a stouter stem
than Lycopodium; its leaves, when seen in profile, seem more rectilinear
and thin; and none of its branches yet found bear the fructiferous stalk
or spike. Its resemblance, however, to this commonest of the
Lycopodia,--a plant that may be gathered by handfuls on the moors by
which the flagstones are covered,--is close enough to suggest a new
reading of the familiar adage on the meeting of extremes. Between the
times of this ancient fossil,--one of the oldest of land plants yet
known,--and those of the existing club moss that now scatters its light
spores by millions over the dead and blackened remains of its remote
predecessor, many creations must have intervened, and many a prodigy of
the vegetable world appeared, especially in the earlier and middle
periods,--Sigillaria, Favularia, Knorria, and Ulodendron,--that have had
no representatives in the floras of latter times; and yet here, flanking
the immense scale at both its ends, do we find plants of so nearly the
same form and type, that it demands a careful survey to distinguish
their points of difference. Here, for instance, to illustrate the fact,
is there a specimen of _Lycopodium clavatum_, from one of these
Caithness moors, that agrees branch for branch, and both in the
disposition of its scales and in general outline, with the specimen in
the stone. What seems to be an early representative of the Calamites
occurs in the same beds. Some of the specimens are of large size,--at
least from nine inches to a foot in circumference,--and