﻿174 



REPRODUCTIVE STRUCTURES. 



nearly the appearance of a fruit of WUliamsonia gigas figured by Saporta (125, 

 plate 244, fig. 3). In the latter case the bracts are broader. Moreover, the associ- 

 ated disk shown by Saporta (Joe. at., fig. 4) may have been shed by just such an 

 ovulate fruit as either of the present ovulate forms when younger. Wherever such 

 fruits are found isolated there is naturally a strong suggestion that they had longer 

 peduncles than any of the Black Hills fruits appear to have had. But in any case 

 stress may be once more laid upon the fact that there appears to be a close com- 

 munity of form between the fructifications of the great branching trunks like 

 C. s uper ba and others of its kind on the one hand, and WUliamsonia on the 

 other. These several genera must have belonged to the same family, but only 

 when the various possibilities of form and association involved in the growth from 

 the youngest stages to full maturity of such bisporangiate flowers as those before 

 us are fully considered, can we gain a fair idea of how diverse such a family might 

 be, and how difficult is the interpretation of the evidence afforded by a series of 

 isolated and dissociated fossil stems and fruits, such as Williamson first studied. 



CYCADEOIDEA PAYNEI (?). 



A small fragment of a trunk of doubtful species, numbered 493, bears several 

 very young fruits of some interest, since one is simply ovulate, while the other 

 consists in an ovulate center surrounded by a thin, structureless tissue zone, 

 interpreted as a very young staminate disk. Both these young fruits are less than 

 a centimeter in diameter. The zone of seed stems is plainest in the ovulate fruit, 

 and several of the ovules are already well outlined, although very small. The 

 enveloping bracts are small but distinct, and quite closely appressed to the 

 ovulate surface. In the transverse section of the other fruit of trunk 493 the base 

 of the central cone is distinctly fluted and surrounded by a thin, correspondingly 

 fluted, structureless annulation that can not be satisfactorily explained as other than 

 a very young disk [cf. photograph 2, plate xliii). If these two fruits are char- 

 acteristic, the trunk bearing them is of course monoecious. But in the case of 

 such young forms from a fragmentary trunk the evidence is only a little completer 

 than that afforded by isolated specimens, while so many categories of inquiry are 

 left unsatisfied that it is well-nigh idle to speculate on them, all the more so because 

 finely preserved trunks which will yield definite and connected facts concerning 

 their fruit habits await investigation. 



CYCADEOIDEA COLEI (?). 



A small trunk, No. 80, somewhat doubtfully referred to Cycadeoidea Co/ei, bears 

 the finely preserved and very young ovulate strobilus, from near the base of which 

 has been cut the transverse section shown in photograph 1, plate xliii. The main 

 point of interest here is that another example of an ovulate fruit is added in which, 

 with vigorous growth of the very young seed zone, there is no direct evidence of 

 the previous maturity of a staminate disk. But a disk annulation or shoulder is as 

 usual present at the base of the ovulate cone, and it is by no means certain that a 

 functional disk was not present a short time previous to fossilization. 



