254 PROF. W. C. WILLIAMSON ON A NEW FORM 



are thus converted into pyriform openings (/) perforating 

 the bractigerous disk. The vertical section^ of which one 

 side is represented in fig. 7^ seems to indicate that the disk 

 attains its greatest development a little below the actual 

 node of the axis which is indicated by fig. 7 e, since at c 

 we have cellular tissue extended peripherally towards the 

 bractigerous disk below, whilst at c we have a similar ex- 

 pansion of the axis proceeding towards the next disk above, 

 the next superior node (corresponding to e) not being 

 contained within the section. The axis at the internodes 

 (fig. 5) is closely invested by the mass of sporangia, the 

 outlines of which are often more distinctly traceable here 

 than in fig. 4; but in other respects the unfigured peripheral 

 portion of the former section corresponds closely with the 

 lower part of fig. 4. At this part of the internode the spo- 

 rangia have obviously no connexion with the central axis, 

 beyond that of mutual contact ; but the lines of their inter- 

 sected walls can be traced, in several instances, radiating 

 from the isolated sporangiophores. The entire thickness of 

 the wall of the axial cylinder at this point is about -g\) of 

 an inch at the ridges (fig. 5 c), and -^ of an inch at the 

 intervening grooves. 



Fig. 6 represents a vertical section made through the 

 centre of the segmentfigs. i and2. a is the medullary cavity, 

 bounded on each side by the woody axis. At c we have a 

 contribution from part of the internode immediately above 

 the node, towards the formation of the bractigerous disk, 

 k ; and from the latter there ascends obliquely upwards and 

 outwards the sporangiophore, h. At A: we find the bracti- 

 gerous disk continuing its outward course for a short 

 space in the horizontal plane, then bending suddenly down- 

 wards in a sweeping curve, and resuming its upward course 

 to support the bracts (k') investing the exterior of the strobi- 

 lus. All the darkly shaded portions of this figure represent 

 sporangial masses — the rounded portion, i, being especially 

 invested with the cellular wall of this sporangium, showing 



