WIILIAMSONIA. 179 



1883. Willimnsonia gic/as, 'Williamson, E. Instit. Gt. Brit. 1883, p. 3, 

 figs. 1-4. 



1889. Cf. WilUamsonia virginiensis, Fontaine, Potomac Flora, p. 273, 



pis. cxxxiii. and clxv. 



1890. Zamites gigas, Schenk, in Zittel, p. 218. 

 WilUamsonia gig as, itid. p. 219. 



1892. WilUamsonia gigas, Fox-Strangways, Tab. Foss. p. 142. 



Type-specimens. The specimens of flowers figured by Williamson 

 are in the possession of Mrs. Crawford Williamson. Those figured 

 by PhilHps and by Young & Bird are in the Whitby Museum. 

 [The original of ManteU's figure of the fiower published in the 

 Medals of Creation (p. 16) is in the Museum of Practical Geology, 

 Jermya Street, London.] 



Main stem similar to the ordinary type of Cycadean trunk in 

 being covered with persistent bases of petiole. Leaves pinnate, 

 agreeing in habit with the fronds of most recent species of Cycadacese ; 

 the crowded linear lanceolate pinnae with acuminate apices are 

 attached to the upper face of the rachis by their slightly rounded 

 ibases, which were probably swollen, as in several recent species in 

 which the pinnae possess a basal callosity. The stiff lamina of the 

 pinnae is traversed by several parallel, or slightly spreading, and 

 occasionally forked veins. The lower part of the rachis is prolonged 

 below the basal pinnae as a petiole attached by a swollen base to 

 the stem. The pinnae are for the most part given off from the rachis 

 at a wide angle ; in the lower portion of the frond the pinnae are 

 shorter and broader and almost at right angles to the axis ; in the 

 middle of the frond they are more crowded, longer, and given off 

 ^t an acute angle, while towards the apex of the frond they are 

 narrower, and attached at a much more acute angle, or almost 

 parallel to the rachis. 



From the main stem were given off one or more comparatively 

 slender branches ('peduncles ') bearing linear acuminate scale-leaves 

 often clothed with ramenta ; each of these branches terminated in 

 an ovoid flower surrounded by liueax bracts, and probably agreeing 

 in structure with the flower of Bennettites. 



The above description is far from complete, but it is intended 

 to convey a general rather than a detailed view of the plant as 

 a whole. In all probability the flowers of the genus WilUamsonia 

 agreed in essentials with those of the Lower Cretaceous and Wealden 

 Bennettites, but unfortunately the absence of internal structure 



