From this triple composition or union of sporules, which differs from the constant quadruple union in tribes of existing plants, namely, Ophioglosseæ and Lycopodiaceæ, which, from other points of structure, may he supposed most nearly related to the fossil, I have called it Triplosporite, a name which expresses its fossil state, the class or primary division to which it belongs, and its supposed peculiarity of structure.
The structure of the axis, which is well preserved in the specimen, distinctly shows, in the arrangement of its [471 vascular bundles, a preparation for the supply of an equal number of bracteæ. These vascular fasciculi are nearly equidistant in a tissue of moderately elongated cells.
The vessels are exclusively scalariform, very closely resembling those of the recent Ferns and Lycopodiaceæ; and among fossils, those of Psarolites, Lepidodendron, and its supposed fruit, Lepidostrobus, as well as several other fossil genera; namely, Sigillaria, Stigmaria, Ulodendron, Halonia? and Diploxylon.
The coat of the sporangium appears to be double; the outer layer being densely cellular and opake, the inner less dense, of a lighter colour, and formed of cells but slightly elongated.
On the lower or adnate side of the sporangium this inner layer seems to be continued, in some cases at least, in irregular processes to a considerable depth. I cannot, however, find that the sporules are actually formed in this tissue, but in another of somewhat different appearance and form, of which I have been only able to see the torn remains.
The minute granular bodies which accompany the sporules in the drawing Tab. 35 (XXIV), fig. G, are probably particles of the mother cells, and are neither uniform in size nor outline.
The whole specimen has suffered considerable decay or loss of substance, which is most obvious in the sporangia from their greater transparency, but equally exists in the opake bracteæ, in which radiating crystallization occupies the space of the removed cellular substance.
