MARATTIACEAE 
fissions in Aaudfussia supports this view (Fig. 281 a-e, lower series). 
S11 
Thus 
the apparently aberrant genus may be brought into line with the rest. It 
will be seen later that this spreading 
of the sori over an enlarged leaf- 
surface has its parallels among the 
Leptosporangiate Ferns also. 
The normal arrangement with 
one row of sori on either side of 
the midrib corresponds to what is 
frequently seen in the fossils which 
this affinity: as 
examples Asterotheca, Scolecopteris, 
and Ptychocarpus may be quoted 
(Fig. 282, also Fig. 288 a). In 
all of these, though the pinnules 
are small, the arrangement of the 
sori is on the same plan. But 
among the Fern-like plants of the 
Palaeozoic age many other arrange- 
ments occur which appear to have 
no near correlative among 
Ferns. 
are referred to 
living 
Diagrammatic view of a trunk of a Fern from the 
Coal, showing above the external cortex with petiolar 
scars (Caulopteris), and below the woody cylinder 
with scars corresponding to the foliar strands, and 
their sclerotic sheaths (Ptychopteris). Reduced to 
+ natural size. (After Zeiller). 
The examples here chosen from among the fossils are those in which 
there is at present no reason to doubt the homosporous Fern-character. 
It is possible that some of them may ultimately be shown to be Seed- 
a, 6, ¢ (above), Danaea data, Smith. 
arrow ‘indicates an abnormal fission ; 4, c, show more numerous abnormal fi 
a=a fertile pinna with many normal sori: the 
ions, resulting 
in irregularly formed sori, distributed over a slightly enlarged leaf-surface. x2. a,c 
(below), sori of Kazulfussia aesculifolia, Blume, showing states of partial or complete 
abstriction. 
Plants, and the sori to represent groups of pollen-sacs. 
But even if they 
were, the structural similarities would remain, and they would then only 
strengthen the opinion that the Pteridosperms had an ultimate origin in 
a Fern-like ancestry. 
