180 BOTANICAL GAZETTE [ SEPTEMBER 
Of even greater interest is the simultaneous discovery of a 
paleozoic lycopod each of whose sporangia contains a single 
megaspore or embryo sac, which presumably was fertilized while 
still attached to the plant, with the condition that I have 
described above that obtains in S. rupestris and S. apus. Of the 
integument that grows up about the sporangium of the Cardto- 
carpon anomalum, described by Scott, leaving at the top an open 
slit-like micropyle, there is no trace I think, except that in S. 
rupestris, quite late in the development, after the embryo has 
formed, the megasporangium becomes sunken in a shallow pit 
formed by the. cushion-like upgrowth of the sporophyll around 
the pedicel. This outgrowth hedges in the ligule with the 
sporangium, and may be homologous with the Lepidostrobus 
integument. Scott’s statement, therefore, that ‘the recent dis- 
covery of Lepidostrobi with integumented, seed-like sporangia, 
in which only one megaspore came to perfection, shows that 
some paleozoic members of the group went far beyond any of 
the living representatives in the differentiation of their repro- 
ductive organs,” needs modification in view of the fact that 
S. rupestris normally at the present day produces seed-like 
sporangia with well developed embryos. 
SUMMARY. 
1. In both S. apus and S. rupestris the sporangium frequently, 
if not always, may be traced to a single superficial cell, the 
archesporium. 
2. The sporogenous tissue may arise in two ways. First 
(S. rupestris), from the single hypodermal cell formed by the 
archesporium being divided by a periclinal wall, thus producing 
a wall and a sporogenous cell. Second, by the archesporium 
(which in this case is assumed to consist of two independent 
superficial cells) dividing into four cells by a periclinal wall, the 
two hypodermal cells thus formed developing the sporogenous 
complex. In each case the epidermal cells form the sporangium 
wall. It is possible but not demonstrated that the second case 
may be a phase of the first wherein the original superficial 
archesporial cell divided by an anticlinal wall. 
