﻿V'Ol NG FRUCTIFICATIONS. 



175 



CYCADELLA WYOMINGENSIS. 



1.) 



(Figure 93, 



The handsome group of silicified trunks from Carbon County, Wyoming, as 

 noted elsewhere, affords in many instances wonderfully preserved structural details. 

 Finely preserved laterally borne fronds have been found embedded in the armor of 

 these trunks, and the discovery of the young strobili is hence all the more satisfactory 

 as going far to complete our knowledge of both the vegetative and reproductive 

 characters. A basal section through one of these strobili displays an ovulate cone 

 several centimeters in diameter, but with very young sporophylls, no very great 



1 11 



S33S. 



Fig. 93. — Transverse sections of young bisporangiate strobili of the Cycadeoideae. 



I. Cycadella wyomingensis. X 4. A very young fructification still folded and deeply immersed in 

 ramentum. Exteriorly 13 discrete fronds are cut slightly above their monadelphous basal union, 

 and interiorly the summit of the central ovulate strobilus is surrounded by the decurved tips of the 

 disk fronds. The space between the frond bases and tips is densely packed with pinnules, there 

 being a very distinct suggestion that a bipinnate condition is present. Distinct synangia have not 

 yet appeared, or at least can not be distinguished. The number of fronds agrees with C. ingens. 



II. Cycadeoidea superba. S. 335. X 3. A very young fructification deeply embedded in ramen- 

 tum and cut through the continuous base of the staminate disk near the base of the central ovulate 

 cone, the level being relatively much lower than in the preceding section. There is especially to 

 be noted a tendency of the young and short interseminal scales to form groups or tufts, as of very 

 short secondary axes. No seeds are apparent. 



differences from other types of simply ovulate cycadeoidean strobili being evident. 

 It is, however, probable that many of the Cycadella fruits protruded farther beyond 

 the armor when approaching maturity than did those of most other Cycadeoideae. 



It is of no little interest to note in this connection that in a section through 

 the basal region of an ovulate cone of Cycadella — trunk 500.88, cf. Ward (178) — 

 the structure of the very young interseminal scales, the most reduced and minute 

 yet observed, comes out with diagrammatic clearness. In these young scales, no 

 more than 0.75 mm. in length by 0.15 mm. in diameter, the cells are thick-walled 

 throughout and scalariform. In the basal region the cells are elongate — nearer the 

 summit less and less so exteriorly, the outer layer finally being made up of squarish 

 palisaded cells one cell in thickness. Beneath this outer layer the cells are rela- 

 tively large and heavy-walled to a depth of several cells, inclosing the innermost 

 tissue composed of a group of about twenty small, much-lignified bundle cells very 

 prettily conserved, as seen in transverse section. Between these minute scales very 

 young intervening seeds are preserved in outline only. 



In addition to the preceding specimens sectioned and studied there was cut 

 from the type specimen of Cycadella zvyomuigensis the smallest bisporangiate stro- 



