Benson.—Mazocarpon or the Structural Sigillariostrobus. 589 
PLATE XVIII. 
Fig. 15. Mazocarpoii Cashii. Part of the transverse section of a cone from the axis of which 
the sporangia of Fig. 17 had become detached. The hexagonal form of the axis and the details of 
the leaf-traces are well.shown. M. Cn. 472 A. x 25. 
Fig. 16. M. Cashii. Obliquely tangential section through a sporange in which the germinating 
spores have not yet reached their final form. The spore on the right can be seen to have already 
established its centroscopic position, for its organic apex is directed towards the tapetal covering of 
the subarchesporial pad. The space occupied by the sporogenous tissue, s.t., would eventually have 
been occupied by the convex base of the ‘ spore’, as in Figs. 1 and 18. A large mass of transfusion 
tissue is seen at tr. As Fig. 15. 
Fig. 17. A low-power photograph of part of the fragmented cone, parts of which are shown in 
the two previous figures. The section passes through several overlapping bracts, A, one of which 
shows the adaxial groove, b.g. As Fig. 15. x 12. 
Fig. 18. Part of the middle section of a series of three through a fine megasporahgial cone. It 
shows a radial section through a sporange on its bract, A, and the bract, A., of the sporange above 
fitting into the groove between the distal lamella, d.l., and the fertile part of the sporange. 
Unfortunately the coal ball had been cut away too close to the cone, so that the distal ends of the 
lamella and bract are incomplete. Six spores can be counted in this section of a sporange, three of 
which are cut radially through the organic apex. The spore on the right shows prothallial tissue 
and an archegonium, a., but the prothallus has been invaded by a stigmarian rootlet. In the 
original the vascular bundle, v.b., can be detected in the pedicel. S. Cn. 1926; Hough Hill; 
Staly bridge, x 15. 
Fig. 19. A surface section of the axis of the above cone showing the form and small size of the 
cone-scale scars (bract scars), b.s. S. Cn. 1925 ; Hough Hill, x 15. 
Fig. 20. A transverse section of the upper part of another megasporangial cone. The hexagonal 
form of the axis and inner cortex is well shown, while the stele is circular in section. Note also the 
constriction of the bases of the bracts, which is a Sigillarian character. H. Cn. 527,7; Shore, x 13. 
