of an oval form, and, bearing
each a round impression in its centre, they somewhat resemble rows of
staring goggle-eyes; while the carvings in yet another species (_S.
pachyderma_) consist chiefly of crescent-shaped depressions. The roots,
or rather underground stems, of this curious genus attracted notice,
from their singularity, long ere their connection with the carved and
fluted stems had been determined, and have been often described as the
"stigmaria" of the fossil botanist. They, too, have their curious
carvings, consisting of deeply marked stigmata, quincuncially arranged,
with each a little ring at its bottom, and, in at least one rare
species, surrounded by a sculptured star. Unlike true roots, they
terminate abruptly; each rootlet which they send forth was jointed to
the little ring or dimpled knob at the bottom of the stigmata; and the
appearance of the whole, as it radiated from the central mass, whence
the carved trunk proceeded, somewhat resembled that of an enormous
coach-wheel divested of the rim. Unfortunately we cannot yet complete
our description of this strange plant. A specimen, traced for about
forty feet across a shale bed, was found to bifurcate atop into two
great branches,--a characteristic in which, with several others, it
differed from most of the tree-ferns,--a class of plants to which
Adolphe Brogniart is inclined to deem it related; but no specimen has
yet shown the nature of its foliage. I am, however, not a little
disposed to believe with Brogniart that it may have borne as leaves some
of the supposed ferns of the Coal Measures; nowhere, at least, have I
found these lie so thickly, layer above layer, as around the stems of
Sigillaria; and the fact that, even in our own times, plants widely
differing from the tree-ferns,--such, for instance, as one of the
Cycadeae,--should bear leaves scarce distinguishable from fern fronds,
may well reconcile us to an apparent anomaly in the case of an ancient
plant such as Sigillaria, whose entire constitution, so far as it has
been ascertained, appears to have been anomalous. The sculpturesque
character of this richly fretted genus was shared by not a few of its
contemporaries. The Ulodendra, with their rectilinear rows of circular
scars, and their stems covered with leaf-like carvings, rivalled in
effect the ornately relieved torus of a Corinthian column: Favularia,
Knorria, Halonia, many of the Calamites, and all the Lepidodendra,
exhibited the most