952 MR, A. C. SEWARD AND MISS S. 0. FORD ON 
furnish trustworthy data. Towards the close of the Palaeozoic period the records of 
plant-life become very meagre, and it is not until the latter part of the Triassic period, 
and in rocks of Rhætic age, that we find an assemblage of fossils comparable with the 
wealth of material from Permo-Carboniferous beds. 
There is no doubt that the Osmundaceous type was abundantly represented in the 
vegetation of the Rhzetie period. We can detect no essential difference between various 
fronds of Rhetic age and others from different Jurassic horizons*. It is enough for 
our purpose to draw attention to some of the more important facts bearing on the past 
history of the Osmundaceze, without entering into a detailed systematic examination of 
fossil records. We use the specific name Todites Williamsoni in a comprehensive sense 
as standing for a well-marked central type of frond, including both Rh:etic and Jurassic 
forms, which are no doubt not always specifically identical. 
Topites WitLiAMSONI T. (Pl. 27. figs. 1, 8, 9, 11, 13.) 
1828. Pecopteris Williamsoni, Brongniart, Hist. vég. foss. p. 324, pl. 110. figs. 1 & 2. 
P. whitbiensis, id. ibid. p. 321, pl. 109. fig. 204. 
1829. P. recentior, Phillips, Geol. Yorks. p. 148, pl. 8. fig. 15. 
1833. Neuropteris recentior, Lindley & Hutton, Foss. Fl. vol. i. pl. 68. 
: 1835. Pecopteris dentata, id. ibid. vol. iii. pl. 169. 
1836. Acrostichites Williamsoni, Góppert, Foss. Farn. p. 285. 
The bipinnate fronds of this species (Pl. 27. fig. 1 & 11) are characterized by the broad 
straight rhachis bearing long linear pinne of uniform breadth which gradually taper to 
an acuminate apex. The pinnules are attached by a broad base and closely set ou the 
pinne ; they are slightly faleate, the side towards the rhachis is strongly convex, and the 
outer margin is straight or concave and bulged outwards towards the base of each 
segment. 
"The fertile pinnules have usually the same form as the sterile, their under surface 
being covered with large spherical sporangia (P1. 27, fig. 13). Well-preserved sporangia 
have been described by Schenk ` from Rh:etie examples from Persia, and by Raciborski § 
(Pl. 27. figs. 8 & 9) from specimens from Lower Jurassic beds near Cracow. We have 
found equally good sporangia on fertile specimens (e. g. Pl. 27. fig. 11) from the Inferior 
Oolite rocks on the Yorkshire coast. The sporangia agree in the absence of an annulus, 
as well as in their form and manner of dehiscence, with the Osmundaceous type. 
In the fossil fronds the fertile pinnules are very numerous, and the sporangia usually 
cover the whole of the under surface of the lamina. It is noteworthy that Mesozoic 
Ferns often appear to have been more richly supplied with sporangia than their modern 
representatives. This is the case as regards Todites and the fossil species of Matoninez ||. 
. The following incomplete list serves to illustrate the abundance of Todiles in both 
the Rheetic and the higher Jurassic strata :— 
* Seward (1900), p. 59. 
* For other figures, see Seward 5 
$ Schenk (1887), pl. 3. fg. 3. eward (1900), pls. 14, 15, 21. 
$ Raciborski (1894), pl. 6. || Seward (1899). 
