CHAPTER XXXVII. 



BENNETTITALES (continued). 



WILLIAMSONI A. Carruth ers. 



THIS genus was first figured by Young and Bird 1 from speci- 

 mens obtained from Lower Estuarine beds near Whitby : these 

 authors compared the fossils to the head of an Artichoke 

 (Cynara integrifolia), 'the covering or calyx consisting of numerous 

 lanceolate and striated leaves' (fig. 544). In 1840 Williamson 2 

 noticed the association with fronds of Zamia gigas Lind. and 

 Hutt. of 'a remarkable fossil, apparently connected with the 

 fructification of a Cycas,' and some years later Yates 3 expressed 

 the opinion that the fructifications figured by Young and Bird 

 probably belonged to the plants which bore the fronds known as 

 Zamites gigas. Leckenby 4 figured some leaves of Palaeozamia 

 pecten (= Ptilophyllum pecteri) in close association with a small 

 flower of Williamsonia which was subsequently recognised as a 

 whorl of microsporophylls. In 1870 two papers of exceptional 

 interest were published, one by Williamson 5 who was the first to 

 attempt an exhaustive account of the genus, and the other by 

 Carruthers 6 who proposed the name Williamsonia, thus associating 

 "with a group of the most characteristic Yorkshire fossils two 

 men (father and son) who have largely contributed to the exposition 

 of Yorkshire geology.' Carruthers instituted a new tribe William- 

 sonieae for the genus Williamsonia, the type-species being 

 Williamsonia gigas : the specific name had been previously given 

 by Lindley and Hutton to the fronds (Zamia gigas) of the plant 



1 Young and Bird (22) A. For a fuller account of the history of our knowledge 

 of Williamsonia, see Seward (95) A. p. 146 



2 Williamson (40) p. 230. 3 Yates (55). 

 4 Leckenby, A. (64). See also Seward (00) B. p. 190. 



6 Williamson (70). 6 Carruthers (70). 



