274 Mr Seivard, On the leaves of Bennettites. [Mar. 8, 



surmount the difficulty presented by the almost constant occur- 

 rence of plant fragments as isolated and imperfectly preserved 

 fossils. We are now in possession of most of the data as to the 

 essential features of the Bennettitean inflorescence, but we have 

 hitherto had no satisfactory proof as to the nature of the vegetative 

 organs which were borne by Bennettites. 



The juxtaposition of plant fragments in the same rock cannot 

 as a rule be accepted as evidence of much value. There is no 

 more serious difficulty in palseobotanical work than that of piecing 

 together detached portions of the same species, and the isolation 

 of members of one individual has given rise to a multiplication of 

 generic terms which, though a matter of necessity, has been a 

 source of no little confusion. Anyone at all familiar with the 

 method of occurrence of Williamsonia gig as in the Jurassic beds 

 of the Yorkshire coast must have recognised its almost constant 

 association with Zamites gigas. The association is so frequent as 

 to naturally suggest an original union of the two fossils in one 

 plant. In the classic work by Young and Bird — A Geological 

 Survey of the Yorkshire Coast — published in 1822 1 , a portion of a 

 Zamites gigas frond is represented in Plate II. fig. 2, and in fig. 6 

 of the same plate we have a typical example of Williamsonia. 

 The authors do not give a name to either specimen, but express 

 the opinion that " figs. 2 and 6 appear to belong to one plant ; the 

 former being a leaf, somewhat imperfect, and the latter the head 

 or fruit of the plant 2 ." Bird's drawing of the frond does not do 

 justice to the specimen which is fairly well preserved, and represents 

 a perfectly characteristic example of Zamites gigas. The original 

 fossils figured in Young and Bird's work are preserved in the 

 Whitby Museum. The late Prof. Williamson devoted a consider- 

 able time during the earliest years of his scientific life to the 

 investigation of the fossils to which Carruthers gave the name 

 Williamsonia. No one has had opportunities of studying this 

 genus as it occurs in the rocks near Scarborough equal to those 

 enjoyed by Williamson ; and it is interesting to find that the most 

 recent work has tended to support many of the conclusions arrived 

 at by this observer. As early as 1834 Williamson 3 expressed the 

 opinion that Zamites gigas was connected with Williamsonia, and 

 in his very able paper, published in 1870 4 , this author is confirmed 

 in the view of the organic connection of these two sets of fossils. 

 This opinion was also shared by Brongniart 5 , who received an 



1 Young, E. and Bird, J., A Geological Survey of the Yorkshire Coast, Whitby, 

 1822. 



2 Ibid. p. 183. 



3 Geol. Trans. [2] Vol. v. p. 230, 1834. 



4 Linn. Trans. Vol. xxvi. p. 663, 1870. 



5 Tableau Veg. foss. p. 62, 1849. 



