EQUISETUM.—(1) Upper part of fertile plant of E. limosum; (2) one of the shield shaped scales or receptacles of the spike, with the six sporangia underneath, enlarged; (3) same seen from below, discharging the spores; (4) a magnified spore with the club shaped filaments spreading; and (5) the same with the filaments coiled up.
LYCOPODIUM.—Plant of L. Carolinianum, and (1) a magnified scale of the spike removed, with the sporangium in its axil, discharging powdery spores.
SELAGINELLA.—Plant of S. rupestris; (1) part of a fertile spike, enlarged; (2) scale from the upper part of it, with its sporangium, containing innumerable powdery spores; (3) scale from the base, with its sporangium containing few large spores; and (4) three large spores.
ISOETES.—(1) Plant of I. lacustris; (2) sporocarp containing the minute spores, cut across, enlarged; (5) same divided lengthwise; (3) sporocarp with the large spores, divided lengthwise; and (4) three large spores more magnified.
AZOLLA.—(1) Plant; (2) a portion magnified, with conceptacles of both kinds; (3) the macrosporic one, more magnified; (4) the microsporic one, more magnified; (5) the same burst open, showing the stalked microsporangia; (6) one of the latter more magnified; (7) another bursting; and (8) three masses of microspores beset with glochidiate or barbed bristles.
RICCIA.—Plant of R. natans; section of thallus, showing two imbedded capsules and numerous air cavities; spores enclosed in a mother cell; three free spores; and calyptra with style.
ANTHOCEROS.—Plant of A. lævis; portion of the columella and valves of the capsule, with spores and elaters; two spores and two elaters.