574 Benson.—Mazocarpon or the Structural Sigillariostrobus. 
that they offer a marked contrast in that respect with the ‘ spores ’ in 
Fig. 18. 
If one compares the various figures of ‘ spores ’ in PL XVII and Text-fig. 
2, one sees a wide range of form of sectional area, but one must be on one’s 
guard against assuming that the uncut ‘ spores ’ were necessarily so varied 
in form. As already stated, they probably for the most part agreed in 
showing a convex base and a plane or concave upper surface. End 
members in a distal part of the sporange may have been like the radially cut 
spore in Fig. 3, i.e. of the shallow crucible form. Such ‘spores’ when cut 
tangentially show a circular area, as is shown in Fig. 9. As respects the 
early stages of development we know but little. An abortive sporange 
(Fig. 7) contained some rounded bodies larger than the other elements of 
the sporogenous tissue, but they give no evidence of a tetrahedral form. 
The frequent suggestion of the number eight as the maximum of spores per 
sporange is consistent with their development from two tetrads, and their 
origin from a tetrahedral form is indicated by the existence of a triradiate 
scar (H. Cn. 41 shows this feature in tangential section). 
Perhaps the most cogent evidence that the apparently ripe ‘ spore ’ 
always represents a gametophyte is its definite centroscopic orientation. 
This must have necessitated a considerable alteration of form, which indeed 
is indicated in the two sporangia of Mazocarpon Cashii shown in Figs. 16 
and 17. 
Section IV. The Cone . 
One specimen of a cone was secured from Shore material and cut by 
Mr. Lomax transversely in series (H. Cn. 527, 1-9). 
Another cone from a Hough Hill ball, kindly lent by Dr. Scott, has 
yielded three longitudinal sections. The sporangia show mature prothallia, 
and some are cut tangentially, but one exceptionally perfect specimen is cut 
radially (S. Cn. 1925-7). 
There is also a single transverse section of a cone from an unknown 
locality (? Halifax), M. Cn. 472 A, which has been lent by Prof. Weiss. 
The transverse sections of these cones have rendered possible the 
identification of transverse sections of the peduncle, and denuded cone-axes, 
which now prove to be no uncommon objects in Coal Measure nodules (e.g. 
H. Cn. 530, 1-30). These cone-axes have hitherto proved rather enig¬ 
matic structures. 
From the series 527, T-9, it is obvious that the cone was pedunculate, 
and that both the peduncle and the sporophyll-bearing axis were hexagonal 
in transverse section. 
The tangential sections of the cone (S. Cn. 1926) and the transverse 
sections in H. Cn. 527, and H. Cn. 530, 2-30, clearly demonstrate the 
arrangement of the cone-scales in a close spiral. The area of attachment of 
