﻿OVULATE CONES. 



r 3I 



(b) In the case of the above-noted isolated bisporangiate strobilns the ovulate 

 cone is much larger than in certain small cones, as seen in cycad 131, where no 

 evidence of the presence of staminate organs has yet been observed. 



(c) The small ovulate fruits of the present trunks may be normally bisporan- 

 giate, and simply strobili, which not only failed to produce staminate fronds but 

 were destined to abort. This would be the case if the belief expressed above, that 

 fructification took place as the climax in the life of these plants, be correct. 



(d) Young fruits with distinct traces of staminate disks have been observed in 

 other species, and are likely to be found in the present species at any time. 



From the foregoing facts, together with 

 the structural features observed, it is held most ":-._ 



likely that the present species are bisexual, and 

 that a staminate disk was produced while the 

 ovulate strobilus was yet young and probably 

 not sufficiently advanced in growth for close 

 fertilization. In this case after the disk was 

 shed the ovulate axis continued its growth, and 

 the megaspores were later fertilized by the 

 pollen of flowers, perchance borne on other 

 trunks. 



CYCADEOIDEA JENNEYANA (?).* 



The fruits borne by the handsome group 

 of trunks from the Piedmont-Black-Hawk 

 locality on the eastern rim of the Black Hills 

 present essentially the same features as those 

 from Minnekahta, although many of the trunks 

 were of more distinctly columnar form. A very 

 handsome isolated fruit (specimen 710) from 

 the lower end of the locality to the north of 

 Black Hawk is shown in longitudinal section 

 in figure 65. This fruit is partially chalced- 

 onized and exceedingly hard and tough, as are 

 quite all of the specimens from the same region. 

 Little carbon was separated out and little iron 

 seems to have been present during the process of 



silicification, although this was controlled by the original plant structure. As a 

 result, the finer structural details are rather faintly indicated and the ground tissues 



Fig, 65.— Cycadeoidea Jenneyana (?). 

 Longitudinal section through an ovulate 

 strobilus from T. 710, an isolated trunk 

 fragment from Black Hawk, South 

 Dakota. X \'A. 



*In the case of the present specimen only a small portion of the trunk is present, but the fruit is, as 

 named, presumptively that of a trunk of C. Jenneyana. It should, however, be emphasized here that it 

 is as yet wholly impossible to deal with the specific position of this and several of the other ovulate fruits 

 briefly described, in any other than a wholly tentative manner. There are in the collections at hand 

 literally thousands of fruits, if the various stages of growth be included. It will therefore be necessary 

 to prepare a long series of representative sections from the fruits, trunks, and leaf bases of type and 

 cotype material before any arbitrary statements concerning species can be made. A biologic study, it 

 may be repeated, is all that is here presented, the idea being to further continue such study in connection 

 with a revision and classification of the various forms on the basis of both microscopic and macroscopic 

 features. 



