﻿280 AMERICAN FOSSIL CYCADS. 



to be noted in photograph 2 that the fluting of the sterile base of the central cone as sur- 

 rounded by disk remnants is distinct, whereas in the fruit shown in photograph 1 the seed 

 zone is well developed for so young and small a fruit quite to the base of the cone. As 

 before, safe deductions as to the conditions indicated may only be made from such appear- 

 ances and stages of growth when it is known how constantly they appear in series of fruits 

 from the same and different trunks. 



Photograph 4. — Cycadeoidea dacotensis (T. 549). S. 291. X 3-2. Transverse section 

 through an ovulate strobilus, with the receptacle, seed-pedicel zone, ramentum, and bracts 

 all clearly indicated, but without clear differentiation of individual cells, the several tissue 

 zones being traversed by pheno- or sphaerocrysts. This strobilus is one of a group of five 

 in a quite similar stage of growth. 



Photograph 5. — Cycadeoidea dacotensis (?) (T. 505). An ovulate cone with half of 

 the seed pedicel region (S) split away from the conical-shaped receptacle (R) during the 

 process of erosion from the rocky matrix in which the trunk was embedded. A photograph 

 of a longitudinal thin section of this cone nearly parallel to the eroded surface here seen is 

 the subject of plate xxxn, and text-figure 28 is a diagrammatic representation of the cylin- 

 drical transverse section of the armor of the cylindrical trunk fragment from which the 

 cone was cut. In this latter view the present cone does not appear, having been removed 

 for sectioning previous to the polishing of the remainder of the trunk in the form of a 

 columnar segment. [The true species of this fruit remains in some doubt.] 



Photograph 6. — Cycadeoidea Wellsii (?) (T. 400). S. 348. X 3- 2 - Transverse section 

 of a cone with a space (s) between it and the enveloping bracts, apparently left by the 

 shedding of a disk. At c in the cone a cavity has been left by the flowing out into the space 

 j of part of the pithy receptacular tissue when in a macerated condition previous to silicifica- 

 tion or else a viscid or gelatinous condition after silicification. 



Photograph 7. — Cycadeoidea Paynei (T. 434). S. 467. X 3-2. Longitudinal section 

 through a bisporangiate strobilus. R, receptacle ; D, staminate disk borne hypogynously to 

 the large but young apical cone (S) ; d, abscission line of disk; /, mass of wilted and more 

 or less broken-down pinnules of the microsporophylls with intermingled synangia; b, en- 

 veloping bracts. 



The present strobilus is of great importance because cut from a well-conserved half 

 of a trunk, and because it is clearly an example of staminate inflorescence in the Bcnnettites 

 Gibsonianus, B. Moricrei, C. Paynei, C. Wielandi, and C. turrita group of cycadeoidean 

 species. 



Plate XLIV. Cycadeoidea. Young Strobili. 



Photograph 1. — S. 410. X 2. A small isolated ovulate cone cut in both longitudinal 

 and transverse section. A disk insertion is plainly present at the base of the cone, although 

 the disk, as seen in the transverse section .s ^ below (from the plane of the saw cut s s oi 

 the longitudinal section), appears to have loosened. Its apical portions are not preserved. 



Photograph 2. — S. 411. X 2. Serially mounted supplementary transverse sections from 

 the same cone as the preceding, with their respective planes indicated by the lines a-e in 

 photograph I. Section b shows distinct basal fluting of the central cone. 



Photograph 3. — Cycadeoidea dacotensis. S. 471. T. 719. X 2. Young and fluted 

 ovulate cone surrounded by numerous closely packed bracts, with finely silicified leaf base. 



Photography — Cycadeoidea minnekahtensis (?). S. 399. T. 229. X 5- Longitudinal 

 section through summit of very small ovulate cone. (Cf. the illustrations showing a larger 

 cone from T. 229, plate xxxin; also the appended note.) 



Photograph 5. — Cycadeoidea minnekahtensis. S. 351. X 2. Series of bracts with non- 

 preservation of strobilus. 



Photograph 6. — Cycadeoidea superba (type). S. 412. X 2. Transverse section through 

 an axis borne prominently near the summit of one of the branches. Only the outline of 

 the central strobilus is clearly indicated, but faint outlines suggest a bisporangiate condition. 



