KIDSrON: THE FLORA OF THE CARBONIFEROUS PERIOD. 203 
Annularia Sternberg contains those forms with whorled, single- 
nerved lanceolate leaves, widest near the centre like Annularia 
radiata Brongt. (Plate XXXVII., fig. 2), or with spathulate leaves 
like Annularia sphenophylloides Zenker, sp. (Plate XXXYIL, 
fig. 1). The leaves unite at the base and form a very narrow 
collar round the stem. 
Fructification of Calamites. 
The fructification of Calamites consists of narrow linear cones, 
attaining in some species a few inches in length, though in most 
cases they are of smaller size. The arrangement of the sporangia 
in many of these cones is still unknown, but of some a \ery 
complete knowledge is possessed. For their reception several 
genera have been founded, as hitherto it has been generally im- 
possible to refer them to their parent stems. 
The more important of these genera may be briefly described. 
Calamostachys Schimper. (Plate XXX YL, fig. 2). 
The cone is composed of alternating whorls of barren leaves 
or bracts and sporangiferous scales. The basal portions of the 
bracts unite to form an almost horizontal collar which surrounds 
the axis, while the free parts of the bracts rise up almost at 
a right angle, the whole forming a saucer-like structure. Between 
each of these barren whorls is a fertile whorl. This consists of 
slender pedicels or sporangiophores, which spring from the axis 
at right angles and terminate in peltate shields, on the inner 
surface of which are borne four sporangia. Both homosporus 
and heterosporous cones occur in Calamostachys^. 
Pal^ostachya Weiss (Plate XXXIV., fig. 5; Plate XXXVI., 
fig. 3. Palceostachya pedunculata Williamson). 
The cones placed in Faloeostax^hya difi'er from those of 
Calamostachys in the sporangiophores springing from the axis 
immediately above the axils of the bracts and forming with the 
axis an angle of about 45 degrees. 
For cones possessing the general appearance of Calamostachys 
and Palceostachya, but in which the arrangement and position 
of the fertile whorls are unknown, the genus Volkmannia Sternb. 
may be conveniently employed. 
