﻿182 



REPRODUCTIVE STRUCTURES. 



an axis, and was perchance destined to abort following dehiscence of its large, 

 earlier-borne basal disk. The stage of growth so well exhibited in these 

 fruits, however, is apparently the average one reached when the series of events 

 resulting in fossilization cnt short further development. The lateral surface 

 of the trunk was, then, quite evenly fruit-producing, and, while in the absence 

 of thin sections there is no full certainty as to the actual number of cones in rela- 

 tivelv the same stage of growth as fruits x and xiv, this may well be more than 

 forty; that is to say, fully or more than two-thirds of all the fruits borne by the 

 entire trunk. 



1 ?A -"J** t^i^ ^> 



Fig. 98. — Cycadeoidea dacotensis. T. 2 1 4. Fr. XIV. Young ovulate strobilus. Natural size. 



A. S. 560. Transverse section cut near the summit of ovulate cone and about 2 cm. beneath the surface of the armor. Ramentum short 



lined ; bracts in solid black ; size and position of bundle patterns of three upper leaf bases indicated. 



B. S. 56 1. Transverse section cut 2.5 cm. beneath S. 560. This section lies beneath the insertion of most of the bracts, and the peduncle is 



less flattened in the vertical direction than in most cases, b. A single bract belonging to an adjacent fructification. 



As may be seen in figure 98 and plate xxxvni, photographs 1 and 2, the trans- 

 verse sections of fruit xiv and surrounding leaf bases as cut from a cylindrical 

 core are objects of beauty scarcely surpassed among sections of silicified plants. 



fruit n 



This ovulate cone (see fig. 99) is considerably larger than any of the pre- 

 ceding, and although the structure is poorly conserved, there is some evidence that 

 the stage of growth is in advance of that of fruit x, etc. Several other axes are 

 borne by 214 in nearly the same stage of growth. The seed zone is estimated to 

 have a thickness of about 4 mm., or perhaps twice that of the most advanced of the 

 preceding cones, while the receptacle is much larger. A few days, or, at most, a 

 fortnight of growth might, nevertheless, produce all of this really slight difference, 

 excluding of course Nos. ix and vi. 



