27 
mn 
As a further example /azw/ea! may be mentioned, 
very early occurrence. 
i 
Fructifications from the carboniferous formation. 
A=Senftenbergia ophider rmatica : to the right the posi- 
tion of the sporangia on both sides of the median nerve 
of the pinnule: to the left a single sporangium, seen 
from above. B=Hawlea Miltoni: to the right a pinna 
with the sori on the extremities of the lateral nerves: to 
the left a single sorus more highly magnified. C= 
Oligocarpia lindsacides, showing position of the few- 
membered circular sori on the nerves of the pinnule. 
D=Scolecopteris polymorpha, Brongn: to the left a 
pinnule showing the position of the sori in transverse 
: to the right a longitudinal section of a sorus 
in which the sporangia are united below into a columnar 
receptacle. /=Asterotheca sternbergii: to the left the 
pinnule with sori: to the right a side view of a sorus, 
and a sorus in radial section. D and £ diagram- 
atically represented. (All Figures after Stur. From 
Solms-Laubach’s Moss? Botany.) 
Marattiaceous type. It would in fact 
FILICALES 
which of 
is also 
Here the sorus is of the circular form, as before: 
the sporangia are sessile and 
elongated-ovoid in form, and radi- 
ate outwards from the centre of 
attachment, so that the slit of 
dehiscence on the inner side is 
directed upwards, and the spor- 
angium when open has the form 
of a boat (Fig. 289 B). Stur de- 
scribes a rudimentary apical annulus 
in these sporangia, but it is not 
clearly shown in his figures. The 
sorus of S/awlea appears most 
nearly comparable to that of the 
modern Angiopterts, but this com- 
parison would be accepted with 
if the 
scopic details were better known 
by a study of sections. 
the of 
Danaettes certain Ferns have been 
greater confidence micro- 
Lastly, under name 
described, which, so far as can be 
judged from the study of im- 
pressions, conform to the Danaea 
type of sorus (Fig. 290). It may 
be a question whether the rela- 
tion of the sporangia together, and 
the mode of their dehiscence were 
exactly as in the modern Danaea, 
but at least the plants appear to 
have been Marattiaceous, and to 
have had elongated sori. They 
come from the Coal Measures, 
Keuper, and Lias. 
Having regard to the fact that 
above sketched 
but 
genera, it 
the comparisons 
do not relate to one or two, 
different 
appears that there is ample evi- 
dence of the early existence of the 
be difficult to find clearer evidence 
to several 
of affinity between a recent and a fossil group of plants, while, as we shall 
Mr. 
Kidston suggests to me that Asterotheca is really identical with Hazw/ea, 
the 
apparent difference being due to conditions of preservation. 
