﻿DESCRIPTION of PLATES. 265 



Plate XI. Cycadeoidca superba. X -02. 



Photograph I. — An exactly lateral view of the completed type specimen, showing cen- 

 tral parent stem ending in a "crow's nest," with a branch on each side. This view is from 

 the direction indicated by the upper arrow of the lower photograph, and is correspondingly 

 lettered. (Note the basal boss b, which appears in both the present views.) 



Photograph 2. — Basal view of type specimen complete, showing the woody cylinder of 

 the central stem and the connection of the three larger, lower, and earliest formed branches 

 (a), (c), (c). Branches lettered to correspond with photograph 1 and plates ix and x, 

 which show lateral views in the direction indicated by the correspondingly numbered arrows. 

 (See the lateral view of the two branches (<-), (d) in plate ix, and the oblique superior 

 view of the entire plant in plate x.) 



Plate XII. Cycadeoidea Marshiana. 



A branching Cycadeoidean trunk from the Black Hills as mounted in the Yale Museum 

 (No. 300). About one-fifth natural size. This trunk has five branches, the smallest of which 

 has been partially restored. The three larger branches (a), (&), and (c) are of nearly 

 equal size, and formed Zamia-like, early in the life of the plant, so that there is no distinct 

 central parent trunk as in the case of the branching cycads represented on plates vn-xi, 

 although (a) appears to be the largest and oldest. A superior view correspondingly lettered 

 is shown in the succeeding plate xui. 



(The present is the largest fossil cycad ever recovered, the weight as collected being 

 383 kilograms. One of the smaller and most beautifully preserved branches (d) was received 

 at the Yale Museum as a separate specimen nearly two years earlier than the remainder of 

 the trunk. When it was found that there was a missing branch a search made by the 

 writer through the collection first obtained revealed it. The chances against such a for- 

 tunate accident were very great. Even such durable objects as silicified cycads, capable of 

 resisting the weathering action of ten thousand winters, should if possible be collected by 

 knowing and sympathetic hands. As related on page 40 the original presence at the Minne- 

 kahta locality of a branching cycad larger than No. 300 is clearly indicated.) 



Plate XIII. Cycadeoidca Marshiana. Superior View of T. 300. 



Compare with oblique view on plate xn. That this plant early took a tri-ramial form 

 is here evident. The very earliest branch of all to form must have been the largest and 

 most central, or that with the "crow's nest" summit, marked (a). From this older stem 

 plainly springs the smaller of the two minor branches, while the attachment of the other 

 has not been determined. The lettering of the branches corresponds with that of the 

 superior view shown on plate xn. Branches (a), (&), and (c) originally constituted pre- 

 cisely such a clump as that formed by Encephalartos villosus (cf. text-figure 17), (a) being 

 the original trunk of the group, and (d) and (e) secondary branches. 



Plate XIV. Two types of Woody Cylinder in Cycadeoidean Plants. 



Photograph 1. — Cycadeoidea Jenneyana. (T. 178.) X 0.5. Polished basal end of a 

 cylindrical stem segment from near the base of a trunk mostly denuded of its armor. A 

 primary ring of twenty-one bundles incloses the relatively small medulla, which increases 

 but little in width in a distance of 35 cm. The medullary rays are as narrow as those of 

 conifers, and extensive augmentation of the xylem zone has taken place. The nearly solid 

 wood, with a seasonal growth-ring appearance similar to conifers and dicotyls, increased at 

 the expense of the cortical region, which is scarcely a centimeter wide. Whether the 

 growth rings have originated from serial cambiums as in other polyxylic cycads or. as 

 less likely, from a persistent primary cambium, is not wholly clear, as explained in the text, 

 Chapter IV. At the extreme outer edge of the specimen itself a few basal portions of 

 leaf bases of normal cycadean form may be noted. 



Photograph 2. — Cycadeoidea formosa. Basal view of T. 89. X 0.45. Lateral view of 

 same, plate vi, figure 5. A trunk with a very large medulla inclosed by a single but heavy 

 woody cylinder of collateral bundles and a very narrow cortical region (c). x, xylem; 

 p, phloem. 



