TATESIA. 167 



in two or three rows (pi. Ix. fig. 13). The inner surface of the 

 woody cylinder exhibits numerous narrow grooves, being the 

 meshes 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 cortical tissue 

 separates the wood from the base of the petioles. The bases 

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

 Externally they present a rhomboid form, the horizontal diameter 

 of which is but little more than the perpendicular." 



Although the Potton and Leighton Buzzard sands, in which 

 the examples of this species have been found, are of Lower 

 Greensand age, the plant may be reasonably included in the 

 present list as possibly a member of the Wealden flora. 



47029. Portion of a stem preserved in oxide of iron. The 

 inner face of the wood is shown, with the elongated medullary 

 ray cavities ; an impression of this face would present a similar 

 appearance to the medullary cast of BucTclandia. Pith large, 

 surrounded by a zone of wood 1-4 cm. in width, and consisting 

 of two concentric rings. The transverse section does not show 

 any well-marked medullary rays traversing the wood. The 

 petiole bases fairly distinct ; some of them terminate apically 

 in a manner suggestive of a clean surface from which the frond 

 has been detached. Leighton Buzzard. Morris Coll. 



V. 221. Two smaller specimens. A distinct variation in the 

 size of the leaf bases : cf. V. 2610. Leighton Buzzard. 



Morris Coll. 



Cf. Yatesia Morrisii, Carr. 



[Fig. 9.] 



The following specimens in the Beckles Collection, from the 

 "Wealden rocks of Sussex, while agreeing fairly closely with 

 Yatesia Morrisii, possess certain points of resemblance to the 

 genus SucMandia. The external characters correspond to some 

 extent with those in Saporta's genus Cylindropodium, 1 but the 



1 Saporta, Pal. Fran9- vol. ii. p. 265, pi. xlix. 



