156 Lady Isabel Browne. 
arranged. The spiral arrangement was not, however, absolutely 
constant in Halonia , any more than the distichous one in 
Ulodendron, but this was commonly asserted to be due to the fact 
that the cones supposed to be borne on the scars of the latter 
were sessile, so that the bases of the lower sporophylls were 
supposed to be in contact with the stem, while the cones borne on 
the Halonial branches were regarded as being pedicillate. The 
fact that the appendages attached to the Halonial scar sometimes 
bore scales quite different from the vegetative leaves strongly 
supports the view that the axes attached to these scars were 
cones. But as Dr. Scott points out in the last edition of his 
“ Studies,” the doubts as to the nature of Ulodendron require that 
the structure of Halonia should be reinvestigated (14). 
Passing to the consideration of the cones themselves, there is 
the well-known type of Lepidostrobus, undoubtedly representing a 
type of fructification borne by certain species of Lepidodendron and 
Lepidophloios. In Lepidostrobus each sporangium is radially 
elongated for a considerable distance and seated on the upper 
surface of the sporophyll; beyond the sporangium is the ligule and 
beyond the latter the distal end of the sporophyll turns vertically 
upwards (11). The structure of the fructification of Bothrodendron 
is only accurately known in one species, probably the cone of 
Bothrodendron mnndum. As in Lepidostrobus the ligule is situated 
beyond the sporangium. The latter is borne on the upper surface 
of the sporophyll, but it is not radially elongated ; indeed, it is 
more elongated longitudinally than transversely or radially. It is 
borne on a stalk, devoid of vascular tissue, and inserted on the 
horizontally expanded portion of the sporophyll (24). In Spencerites 
another cone, which though clearly Lycopodial, may or not be 
Lepidodendraceous, the sporangia are approximately spherical and 
inserted on a very small parenchymatous ventral projection of the 
sporophyll, to which they are attached by their distal ends. Miss 
Berridge has shown that beyond the sporangium the sporophyll 
turns vertically upwards (2). Besides these types of cone, there is 
that of Sigillariostrobus ; this fructification was, as its name 
indicates, the cone of Sigillaria ; its sporangia are radially elongated, 
though not nearly so much so as those of Lepidrostrobus. If 
Spencerites does not belong to the Lepidodendraceae (and this 
must remain an open question so long as its vegetative parts are 
unknown), it seems not improbable that the Bothrodendron- type 
of cone may be the most primitive within the order and that 
