XXXVIl] 



WILLIAMSONIA 



439 



of the lower part of the cup to break away from the coherent 

 bases of the sporophylls (fig. 551)i, and it is not unlikely that some 

 of the impressions described as infundibuliform appendages are 

 incomplete examples of Williamsonia spectabilis. 

 WilUamsonia Leckenbyi Nathorst. 



This species, founded on specimens from the Middle Estuarine 

 beds exposed on the Yorkshire coast at Cloughton Wyke^, is 

 characterised by the almost spherical form of the strobilus, 

 ^•5 — 5 cm. in diameter. The relatively small receptacle is covered 

 by a thick mass of megasporophylls and interseminal scales 

 except in the lower part which bears only sterile scales. Nathorst 

 believes that the seeds were very small, but no undoubted examples 

 have been found. A specimen in the British Museum, figured 

 m 1900', shows the surface-view of an impression of the base of 



Fig. 553. Williamsonia Leckenbyi. Surface- view and in section. 

 (Restoration after Nathorat.) 



the flower; a small circular raised boss occupies the centre — 

 the scar of the receptacle — and surrounding this is a reticulum 

 formed by the impression of the distal ends of the interseminal 

 scales. TJie uniform nature of the reticulum, the meshes of which 

 are all of the same type, shows that in the basal region of the 

 flower the organs borne on the receptacle were all sterile as 

 in Cycadeoidea (Bennettites) Morierei. Except in the smaller 

 diameter of the receptacle this specimen is practically identical 

 with that of Williamsonia Carruthersi Sew. reproduced in fig. 559. 

 The form of the strobilus is shown in Nathorst's restoration* 

 represented in fig. 553. The interseminal scales have broad peltate 



1 Nathorst (09) PI. i. figs. 1—3. 



2 Ibid. (80) p. 39. See also Saporta (91) p. 161, PI. 248. 



' Seward (00) B. p. 201, fig. 35. * Nathorst (09) p. 14, Pis. n., m. 



