THE PALJEOZOIC SEED LAGENOSTOMA OVOIDES. 481 
shell is not shown here, though, if not, the diameter at this point must be 
still greater than that given above. 
But if this seed is not L. oroides, the question arises as to what other 
species of the genus it belongs. The great size of the particular section 
we possess seems to preclude its identity with any known species of 
Lagenostoma except L. Loma.cii, but that is what we should expect for a section 
across the base of the lagenostome of this species, at least one specimen of 
which may have possessed ten loculi (16, p. 210). 
As militating against its inclusion in this species, however, is the fact that 
although the section is eut at its base, the wall of the lagenostome is very 
distinctly crenulated, while Oliver and Scott state that the crenulations died 
out towards the base of the organ (16, p. 200). 
There remains one further feature to note in this curious specimen, і. e. the 
intrusion of the megaspore membrane into the lagenostome. That this 13 
aetually the case, and that. the appearance is not due to a slight obliquity by 
which the membrane is shaved towards the lower part of the section, is 
shown by the fact that, were this so, the plinth must of necessity be cut, 
and would be seen united to the canopy (cf. Pl. 83. fig. 15), whereas in 
reality the lagenostome wall is quite complete, forming a rough circle. The 
dimensions also, so far as they сап be obtained, agree with the completely 
transverse nature of the section, which is, indeed, what it is stated to be 
(20, p. 239). 
The megaspore membrane normally intruded considerably into the lageno- 
stome of. Physostoma, but no instance of its doing so in a Lagenostoma has 
been recorded, while numerous specimens show it contracted away from 
the nucellus. Perhaps the preparation may best be explained in this 
particular as that of a seed abnormal in the opposite direction to that of 
В. 28 (p. 465), only that while it 13 easy to understand how the lagenostome 
could be dragged into the megaspore by post-mortem changes, it is difficult 
to see how the latter could be forced into the lagenostome either before or 
after the death of the seed. 
V. THEORETICAL SUGGESTIONS. 
Turning first to the integument, without entering upon the vexed question 
of its origin (which is not warranted by the present work), a word may be 
permitted on its more generally admitted homology with the inner layers of 
the Cycad integument. This was first pointed out by Oliver and Scott 
(16, p. 234), who consider that “the canopy may well have undergone 
simplification into the hard integument of a Cycadean seed,” and suggest 
that the outer flesh of the latter with its bundles may represent the cupule. 
The interpretation of the Cycadean integument as a double structure (18) 
supports the view of its origin from the fusion of the two envelopes of a 
