546 FILICALES 
The sporangia of Johria are radially constructed, the apex and base 
being opposite (Fig. 302 D, E). In the other genera the sporangia are more 
or less curved, so as to be dorsiventral : 
this curvature is slight in Azezmia and 
Schizaea (Fig. 302 A, B, F, G), but very 
marked in Lygodium (Fig. 302 C). 
Here it will be well to introduce 
a brief notice of certain fossil sporangia 
which have been referred to this affinity, 
for they help to an understanding of 
the structure of those of living forms. 
The best known of these is Senften- 
Fie; 36% bergia (FPecopteris) elegans, Corda, from 
Senftenbergia (Pecopteris) elegans, Corda. the upper Carboniferous (Fig. 303): it 
4=a small piece of sporophyll (t). B=a spor. corresponds to Sckzzaea both in the 
angium (#2). (After Zeiller, from Engler and < ane 5 ? 
Prantl, Nat. Pfanzenfam.) disposition of the solitary sporangia 
and in their form and mode of dehi- 
scence ; but the annulus is composed of several cell-rows, and the terminal 
“plate” has not been observed. Zeiller points out, however, that this is not 
an absolute difference from living forms, for various species of Lygodium 
(a genus which has itself been traced back 
to the Cretaceous Period), have a partially 
double series of cells of the annulus, while 
the “plate” in living forms is often so 
small that a similar one in a fossil- 
impression might well escape detection.+ 
A second example is the genus A/ukia, 
the fructification of a Pecopterid from the 
Jurassic, of which sgveral species have 
been described by Raciborski.2 Here the 
arrangement of the sporangia, their struc- 
ture, and line of dehiscence are as in 
Schizaea, there being only a single series 
of cells of the annulus (Fig. 304). In 
both of these genera of fossils it is to be Fic. 304. 
noted that the sporangia are intra-marginal, — K7uhia exilis (Philipps). Raciborski. : 
: Fertile pinnule of last order, seen from 
on the lower surface of the pinnule, but jeow (22). From the Jurassic of Krakau, 
Without any indusial protection, while there (fer faciborski, from Engler and Prantl, 
is no specialisation of the fertile pinnules. 
From such comparisons it would appear probable not only that the 
Schizaeaceous type is an ancient one, but that it sprang from plants with 
a Pecopterid type of frond, without differentiation of specialised fertile 
pinnules, and that the sporangia were intra-marginal, on the lower surface. 
1Bull. Soc. Bot. de France, T. xxiv., p. 217. 
2 Englers Jahrb., xiii., p. 1, Taf. 1. 
