Seward: The Jurassic Flora of Yorkshire. 7 
Todites Williamsoni Brongn. (and Cladophilebis denticulata ?). 
Todites Williamsoni, which occurs fairly often in a fertile state, 
is undoubtedly a member of the Osmundaceae, the existing 
species which most nearly resembles the fossil being Todea bar- 
bara of South Africa and Australia. Cladophlebis denticulata, 
though not hitherto found with well-preserved sporangia, 
is probably another member of the same family, an opinion 
which has recently received additional support from the associa- 
tion of sterile fronds of C. denticulata in New Zealand Jurassic 
rocks with well-preserved petrified stems described by Dr. 
Kidston and Professor Gwynne-Vaughan in their admirable 
monograph of fossil Osmundaceae as Osmundites Dunlop. 
GYMNOSPERMAE. A Cycadophyta. The Jurassic flora of 
East Yorkshire is rich in the remains of Cycadean plants, 
a group which it is impossible to deal with adequately in the 
space at my disposal. The Cycads, or as they are sometimes 
called the Sago Palms—a misleading name, as it implies near 
relationship to the Palms—constitute a small sub-division 
of the great group of Gymnosperms, and are now repre- 
sented by a comparatively small number of species 
characteristic of tropical regions. The genus Cycas which 
occurs in India and the Far East is the best known example 
of the class : a well-grown plant has a long columnar stem, not 
infrequently branched in an irregular candelabra-like style, 
bearing one or more crowns of leaves similar in form to those 
of some Palms. The reproductive shoots of recent Cycads 
are in the form of cones, with the exception of the fertile organs 
of Cycas, which are produced from time to time at the apex of 
the stem as a cluster of tawny yellow modified foliage leaves 
bearing laterally placed seeds often attaining the size of a large 
hen’s egg. In all other Cycads the fertile shoots, including 
the male shoots of Cycas, are compact cones which may reach 
a length of more than a foot, and consist of a strong axis bear- 
ing crowded female or male appendages. A few genera of 
Cycads are peculiar to the Australian region; others are 
confined to South Africa, while South America also has its 
peculiar types. Like some recent tropical ferns, the Cycads 
may be regarded as links between the Mesozoic era and 
existing floras. The pinnate fronds of the Jurassic species 
known as Zamites or Williamsonia gigas, bear a close resem- 
blance to those of recent species of the American Zamias and 
other existing genera, but, as the late Professor Williamson 
showed, the plants which bore the Zamia-like fronds possessed 
reproductive shoots differing in several important respects 
from those of any recent genera. Without attempting a 
description of the fossil cycadean fronds, brief reference may be 
made to a point of considerable botanical interest. 
It has been abundantly proved that during the Jurassic 
19gl1 Jan. 1. 
