﻿130 REPRODUCTIVE STRUCTURES. 



Aside from minor differences in form, such, for instance, as the slightly more 

 globular shape of the receptacle, the principal point of distinction between the 

 present fruit and those of trunk 393 is the much more prolific growth of seeds and 

 far larger size of the bracts. These features are also to be seen in the fine longitu- 

 dinal section of another fruit cut from a trunk referred at the present time to Cyca- 

 deoidea Paynei, and shown in plate xxiv, photograph 6. In this latter cone the 

 enveloping bracts rise a full centimeter above the summit of the fruit, and are 

 distinctly larger than those of the otherwise larger fruit of C. JUielaiidi, shown in 

 plate xxiv, photograph 3. Structure is beautifully preserved and characteristic, 

 as clearly appears in figure 60, showing the main features of bract organization. 

 The seeds may or may not have been fertilized. As in the several foregoing species, 

 there are indications of the earlier presence of a basal disk. 



BISEXUALITY. 



(As indicated in the strobili of the closely related group of species, Cycadeoidea 



Paynei, C. Colei, C. McBridei, and C. turrita.) 



It becomes a necessary convenience to add in the present connection a more 

 definite statement of the evidence indicating the frequent occurrence of a bispor- 

 angiate condition in the nearly full-grown or mature strobilar forms just described, 

 although this topic in part anticipates the descriptions of the completely preserved 

 bisporangiate strobili given in the succeeding chapter. For although it was at first 

 supposed that the type of fructification so richly illustrated in the foregoing trunks 

 was simply ovulate, these later studies disprove the correctness of such an interpre- 

 tation so far as most of these ovulate cones are concerned. As yet a trunk of the 

 present species bearing male disks in any considerable number has not been found, 

 although trunk 464, which is possibly of the same species, bears, in addition to 

 some scars left by shed strobili, the same general bisporangiate type as Cycadeoidea 

 daco/e/isis, and no other fruit. In this one, as described more fully in the next 

 chapter, the ovulate axis has assumed considerable size, and it is clear that it con- 

 tinued its growth far beyond the stage seen in the possibly abortive young ovulate 

 cones of trunks like 131, and would doubtless have ultimately matured seeds had 

 fossilization not intervened. A very pronounced feature is the fact that the outer 

 layer of interseminal scales is almost entirely composed of scalariform elements. 

 Likewise the enveloping bracts have the structure seen in those surrounding other 

 and larger ovulate cones. The staminate disk has wilted down, leaving in the 

 space over the ovulate cone a confused mass of sporophylls and fairly well pre- 

 served and distinct synangia, some of which contain pollen. The general type of 

 the ovulate cone, which is much larger than any of the young cones of trunk 131, 

 leaves it most heartily to be desired that among the many trunks to be investigated 

 supplementary examples may yet be found. Now, on the basis of isolated fossil 

 bisporangiate fruits, or even of single trunks bearing advanced stages of ovulate 

 strobili, presumptively derived from bisporangiate axes, it must always prove diffi- 

 cult to determine degrees of bisexuality, moncecism, and dicecism. But the facts 

 pointing to a solution in the present case may be repeated here : 



(a) The structure of all the larger ovulate cones permits the assumption of the 

 earlier presence of an hypogynous staminate disk. 



