﻿BISPORANGIATE AXES. 



153 



relations are markedly different. The tips of the fronds are very much laterally 

 compressed, though still ranged close together in circular order. Their synaugia 

 are clearly set on much longer pedicels, so that there appears to be a median groove 

 of the upper outer surface of the frond. The space occupied by synaugia is mark- 

 edly increased, and the transverse section of the campanulate disk base is no longer 

 annular, but is partly split up into adjacent isosceles triangular segments, with their 

 bases circularly arranged and their vertices corresponding to the inner disk ridges 

 noted in the preceding section. The staminate disk, hence, plainly divides just 

 above the summit of the central cone into a series of free fronds whose rachides are 

 of isosceles triangular section, with the long base or flat side outermost, although the 

 adjacent rachides remain in close contact at their basal angles so as to form a closely 

 set and compact flower bud. That in such a section as the present a few of the 



Fig. 77. — Williamsonia gigas (L. & H.). Natural size. 



A typical disk impression. If staminate. the pinnules were either very closely set or dehiscent. 

 From Seward's Jurassic Flora of Yorkshire, Part I. PI. VII. fig. I . 



rachides are yet seen to be united, while others are free, may much rather be due to 

 obliquity in cutting than to any lack of symmetry, but at the same time proves that 

 the section closely indicates the exact height at which the disk splits up into dis- 

 crete rachides. In these sections none of the tips of the fronds into which the disk 

 thus divides are absent, preservation in the normal unexpanded position being com- 

 plete, except for the erosion of middle portions of rachides forming the apical region 

 of the strobilus, as already mentioned. 



The synangia are also preserved with great clearness of outline and structure 

 in normal form and position, and mostly form series of pairs arranged radiallv like 

 successive Vs set serially into each other in close order, with the arms of the 

 Vs set distally and representing synaugia. These radial rows of pairs of synau- 

 gia alternate with the inner frond tips and their corresponding petioles, and thus 



