220 me. a. c. seward on the [May 1903, 



which the fronds are bipinnate. In some instances we possess 

 information as to the nature of the stems which bore the fronds, 

 and we are familiar with various types of Cycadean inflorescences. 

 The genus Williamsonia is represented by the Jurassic species 

 W. gigcis (L. & H.) and W. pecten (Phill.), characterized by pinnate 

 fronds closely resembling those of certain forms of modern Cycads ; 

 in the case of the former species we have some evidence as to the 

 nature of the stem, which in external form was practically identical 

 with the stems of Macrozamia or Encephalartos among existing 

 genera. 1 I have elsewhere 2 shown that Williamson's opinion, 

 expressed in his important memoir published in 1870, 3 as to the 

 organic connection between the fronds originally named Zamia gigas, 

 L. & H., and the peculiar reproductive shoots named by Carruthers 

 Williamsonia, 4 is confirmed by the evidence of specimens in the 

 Yates Collection in the Paris Natural History Museum. 



It seems clear that the smaller form of Williamsonia, figured by 

 Leckenby in 1864, 5 represents a reproductive organ of the plant 

 which bore fronds previously known as Pterophyllum pecten, L. & H., 

 and now referred to the genus Williamsonia. 



Prof. Nathorst has clearly demonstrated an organic connection 

 between a third type of Williamsonia, W. angustifolia, Nath., and 

 leaves formerly placed in the genus Anomozamites. 6 



We have therefore sufficient evidence to justify the opinion, 

 founded at first on the external resemblance of vegetative structures, 

 that certain of the Cycad-like fronds of Mesozoie age have their 

 nearest living representatives in the Cycadacese. On the other 

 hand, there are numerous forms of pinnate leaves which we 

 are as yet unable to associate with either stems or reproductive 

 organs, but which it is reasonable to regard as fronds of Cycadean 

 plants. Prof. Nathorst has recently suggested the term Cycado- 

 phyta 7 as a convenient designation for fossil Cycadean plants 

 known only as isolated leaves. The morphology of the flowers of 

 some of the Mesozoie Cycads differs in so marked a manner from those 

 of recent forms, that it has been necessary to place them in a 

 separate division — the Bennettitales — of which the English species 

 Bennettites Gribsonianus, Carr., 3 represents the typical example. 



No specimens of the English Williamsonia have so far been 

 discovered of which it is possible to make an anatomical examination ; 

 but it is clear that the type of reproductive shoot represented by 

 Mr. Carruthers's genus is very closely allied to, if not generically 

 identical with, Bennettites? Other fossil reproductive organs are 

 known which present a sufficiently close agreement with those of 

 modern Cycads to warrant their inclusion with them in a separate 



1 Seward (00 3 ) p. 179. 2 Seward (97) p. 274. 



3 Williamson (70). 4 Carruthers (70). 



5 Leckenby (64) [Pal&o~amia pecten] pi. ix, fig. 4 a. 

 G Natkorst (80) & (02) pp. 9 et seqq. ~ Nathorst (02) p. 3. 



8 Carruthers (70) ; Solros-Laubach (90). For an account of the male organ* 

 of Bennettites, see Wieland (99) (99 2 ) & (01). 

 ; ' Seward (95) pp. 146 et seqq. 



