124 G. R. Wieland — Cycadeoidean Flower-bud Structure. 



form normally twenty divisions at the summit of the flower. 

 This latter is the true structure, as would indeed be fully con- 

 firmed without further sections, although there are some "slight 

 departures from entire symmetry of form. 



The presence of outer median rachidal furrows had already 

 been noted in the very different flower of Cycadeoidea Marshi- 

 ana described in Part YI of these studies. This latter, how- 

 ever, is a much smaller species of flower than the form before 

 us, and the microsporophyll surfaces are much more crinkled 

 and rugose ; while the apex was not found present. But a 

 small median outer furrow is present in each rachis, as one 

 readily sees on referring to Part YI of these studies (fig. 3A). 



Figures 2-4. Cycadeoidea colossalis. Drawings showing external and 

 structural features of the bisporangiate flower bud with enveloping bracts 

 either removed or indicated diagranmiatically. About natural size. 



Fig. 2. Exterior view of bud in part diagrammatic and drawn in approxi- 

 mate proportions, the base being somewhat narrow. Note resem- 

 blance to so-called Neuropteris seeds in both form and surface groov- 

 ing. 

 Fig. 3. Same as preceding with one quarter of fruit bud cut away to 



bring to view central ovulate cone. 

 Fig. 4. Drawing of longitudinal section through flower-bud dome (C) 

 extending up to plane (T) of trial section (fig. 1) and surmounted by 

 dome-shaped apex of disk (C) which is shown in full relief, just as it 

 appears after splitting away a portion of the bract husk. 



C, dome formed by extension of paired and closely appressed rachi- 

 dal appendages ; T, plane of trial section (fig. 1); S, synangia : A, 

 decurved tip of staminate frond extending just to base of the ovu- 

 late zone of the central seed cone, which is shown relatively large, 

 being very young and small ; D, disk insertion ; B, L, outer bracts 

 next to leaf base. 



