Mr Thomas, On some new and rare Jurassic plants, etc. 105 
On some new and rare Jurassic plants from Yorkshire: The 
male flower of Williamsonia gigas (Lind. and Hutt.). By 
H. HamsHaw Tuomas, M.A., Fellow of Downing College, Curator 
of the Botanical Museum, Cambridge. 
[Plate VI] 
[Read 22 February 1915.] 
Recent years have seen considerable additions to our know- 
ledge of the reproduction structures (often called ‘ flowers’) of the 
_ Williamsonaia section of the Bennettitales, but several points still 
require elucidation, even in the case of Walliamsonia gigas which 
was the first to be discovered and described. The classic work of 
Williamson* published in 1870 gave an account of the female 
strobilus, and the beautiful specimens on which the paper was 
based are now in the possession of Prof. Seward and have been 
therefore specially accessible for study. More recently Prof. 
Lignier, working from the specimens in the Yates collection in 
the Museum of Natural History at Paris, reinvestigated this 
species} and added much to our knowledge and to the correlation 
with other Bennettitalean flowers. The male sporophylls, however, 
remained unknown, Lignier acknowledging that we had no 
information as to their form or positiont. In 1909, Prof. 
Nathorst§ described some male Williamsonian flowers from 
Whitby, which were found as isolated carbonaceous impressions 
and which he called Wallaamsonia spectabilis; subsequently he 
also described several other species from the same district]. All 
these forms were cup-shaped structures composed of partially 
united microsporophylls, bearing synangia from which the remains 
of pollen-grains could be extracted; they were probably unisexual 
‘flowers. Other observations have since been made, and I have 
collected a number of specimens of various forms{, but the 
question as to the male structures in W. gigas still remains to 
be answered. 
Wieland has maintained that one of the specimens figured by 
Lignier as the cast of the apical part of an ovulate strobilus is 
* «Contributions towards the History of Zamia gigas, Lind. and Hutt.” 
Trans. Linn. Soc. Vol. xxvi. p. 663, 1870. k 
+ ‘Le fruit du Williamsonia gigas Carr. ete.” Mém. Soc. Linn. de Normandie, 
T. xxr. p. 19, 1903. 
+ idem, p. 43. 
§ ‘‘Palaéobotanische,” Mitteilungen 8. K. Vet. Akad. Hand. Bd. 45. Stockholm, 
1909. 
|| ‘* Palaobotanische,”’ Mitteilungen 9, K. Vet. Akad. Hand. Bd. 46. Stockholm, 
1911. 
4{ ‘* Fossil flora of Cleveland district.” Q.J.G.S. Vol. uxtx. p. 230, 1913. 
