ggg MR . W . CARRUTHERS ON FOSSIL CYCADEAN STEMS 



the Secondary rocks. Many of them I have already figured and described 1 . They are 

 cones composed of stipitate and peltate carpophylls, each bearing two reflexed ovules, M 

 in J cephahrtos, Zamia, &c, but agreeing, as regards their small size, with the fruits of 

 the Xew-World Zamiea. As these cones do not belong to BucUandia, nor, as 1 shall 

 pi Miitly show, to Bennettites or Mantellia, it is probable that they are the fruits of 

 Y.ifesia and Fittouia. This supposition is strengthened by the following considera- 

 tions:— 1st, the structure of the stems appears to require deciduous axillary append- 

 ages for th«; organs of reproduction; 2nd, one of these cones (Cycadeostrobus Walkeri, 

 Girr.) has bom found in the same stratum in which the stem of Yatesia Morrisii is found; 

 and, 3rd, the British Museum contains stems of two species of Yatesia, and a cone havin 

 lie same structure as those included in Cycadeostrobus, from the Oolitic Argile des Dives 

 f France. If these considerations are sufficient to warrant us in referring the fruit- 

 included under the name Cycadeostrobus in part to Yatesia, this genus accords with 

 Encephalarto* in the structure of the female cone, as well as in the presence of vascular 

 bundles in the medulla, and in the permanent investment of the stem by the bases of the 

 petioles. Only in the small size of the fruit does it differ from the African genus, this 

 character suggesting an approach to Zamia. 



The following forms most probably belong to this genus : — Mantellia cylindrica, Brongn., 

 I'rodr. p. 90; Buckle ndia gracilis, Pomel, Amtlich. Bericht. d. Gesell. d. Nat. in Aachen, 

 1 17, p. 346 ; Echiuostipes Duvalii, Pomel, I. c. p. 346. 



The genu^ is dedicated to James Yates, Esq., I\ U.S., whose extensive and accurate 

 acquaintance with Cycadece, and whose large collection of plants of this order, are well 

 known. I am indebted to him for information, at all times cordially given, for free access 

 to his collections, and especially for the use I have been able to make of his extensive 

 series of dried stems, leaves, and seeds, which he has presented to the herbarium of the 

 British Museum since I began these investigations. 



Yatesia Morrisii, Carr. (Tab. LY. fig. 3-6.) 



1867. Cycadeoidea Yatesii, Morr. & Carr. Geol. Mag. vol. iv. p. 199, pi. ix. 



8tem cylindrical, covered with the bases of the petioles, which are rhomboidal in form, 



and terminate in a tumid boss, the apex of which is directed upwards. The cellular 

 axis is very large. The pith has disappeared, except in one specimen, where suffi- 

 cient of it remains to show that it was permeated with vascular bundles. The woody 

 cylinder surrounding the pith, in the specimen figured, consists of two rings (figs. 

 5 & 6) ; it is everywhere pierced by medullary rays, which are often so large as to 

 break the continuity of the wood (fig. 6). The sides of the wood-cells parallel to the 

 medullary rays are covered with disks in two or three rows (Tab. IX fig. 13). 

 ine inner surface of the woody cylinder exhibits numerous narrow grooves, being the 

 m< sues for the passage outwards of the vascular bundles to the leaves. These meshes 

 are larger and more regular on the outer surface of the wood. A very thin layer of 

 corneal cellular tissue separates the wood from the base of the petioles. The bases 

 the petioles spring from this layer, at right angles to the stem. Externally they 



1 Seemann's Journal of Botany, vol. v. p. 1 , pi. 1. 



