﻿BISPORANGIATE AXES. 



H5 



trated in plates xxxiv and xxxv, and especially in text-figure 74. These bisporangi- 

 ate strobili, as shown in longitudinal section in figure 7 1, are seated on the stem axil- 

 lary to one or several leaf bases, with their yet folded staminate fronds enveloped by 

 the numerous imbricating bracts. They are from 5 to 10 cm. in diameter, this 

 measurement often being much greater in the lateral direction, as the result of 



',367 



Fig. 72. — Cycadeoidea dacotensis. T. 214. 



Bisporangiate slrobilus in longitudinal section. A composite but in every respect exact figure drawn from the two parallel 

 sections, S. 360 and 361 . That on which the portion of the figure to the left is based cuts the incurved synangia-beanng 

 pinnules throughout their entire length, while the staminate frond to the right is cut on a slightly different plane, so that only 

 the closely packed synangia appear. Only the ascending and descending portions of the rachides of the staminate fTonds 

 are preserved, the part not preserved being indicated in dotted outline. (Compare with photograph 1 , Plate XXXVI.) 



1, 1, Leaf bases originally close together but thrust apart by the emergence of the bract-enveloped strobilus; b, b, bracts; 

 pt. peduncle bundle traces which send branches into the hypogynous staminate disk and then pass on into the ovulate cone ; 

 c, the summit of the cenrjal ovulate cone, which may have been prolonged into a long terminal tuft of hair-like scales. Nos. 

 363, 365-367 [or 1-IV respectively) , position of serial sections shown in figure 73. 



compression, and their length from summit to cortex is about 12 cm., of which the 

 peduncle takes up about half. The upper two-thirds of the lateral surface of the 

 peduncle bears the bracts in rather close spiral succession, and from 100 to 150 in 

 number, as may be seen in transverse section (fig. 75, etc.). The bract tips are not 



