ANATOMY AND AFFINITY OF CERTAIN RARE AND PRIMITIVE FERNS. 391 
in other Gymnogramme types. In the Cheilanthinse, with which Trismeria has 
been associated by some authors, irregularity of sporangial construction is now seen 
to be widespread. To this is added the remarkable irregularity in spore-size and 
output per sporangium in Nothochlsena affinis and Pellsea hastata. These irregu- 
larities will strike the reader as particularly significant as generally affecting the 
Ferns discussed in these pages. Such facts acquire a special value when it is 
remembered how stereotyped are the sporangia and spores of most advanced types. 
The facts appear to indicate that the Ferns now considered are in a transitional 
position. Taking all their characters into consideration, and noting the suggested 
connection between Llavea and Plagiogyria, these Ferns appear to constitute a 
laxly associated group in which the characters of the “ Simplices” are still manifest. 
They all belong to the “ Superficiales,” and in the light of our present knowledge 
their probable origin may now be indicated. 
It has recently been suggested by Professor Bower that the distinction between 
the “ Superficiales ” and the “ Marginales ” is based on the relatively early assumption 
in descent of the superficial position for the sorus in the former and the retention 
of the marginal position in the latter to the present day {Ami. Bot., 1918). From 
this it is suggested that on the point of soral position the “ Superficiales” generally 
will group themselves in relation to the relatively primitive Gleicheniacese, while 
the “Marginales” may be affiliated to the Schizseacese. Certain types, however, 
may be held to take an intermediate position. The underlying hypothesis is that in 
the ancestry of these Ferns the prevalent or universal position of the sorus was 
marginal, and that in certain forms for which an intermediate position is claimed 
indications may still be seen of an original marginal position for the sporangia. 
These may be viewed as more directly referable to some Schizseoid source. It 
has been shown by Prantl in 1882 (Engler’s Bot. Jahrb., p. 482) that in Pellsea , 
Cryptogramme, Nothochlsena, and others the first sporangium appears always at some 
distance from the leaf-margin, but in Cheilanthes it is quite close to it, so that as 
the young sporangia develop at first quicker than the margin the appearance is 
almost as though (as they' actually do in Schizsea and Mohria ) they spring directly 
from the . marginal cells. Sir Vm. Hooker has noted that Mohria combines the 
capsule of the Schizseacese with the habit of Cheilanthes ( Syn . Fil., p. 436). When 
to this similarity of habit between Cheilanthes and Mohria is added the soral 
comparison between Cheilanthes and the Schizseacese the suggestion of a phyletic 
relationship of Cheilanthes with the Schizseacese seems remarkably strong. But it 
has been noted that Cheilanthes shares with Jamesonia, Llavea, Trismeria, Pellaea, 
Nothochlsena, Cryptogramme, Plagiogyria, and Ceratopteris an exceptional sporangial 
variation which may be indicative of kinship. It may be held that although in these 
latter a close association of the sporangia with the leaf-margin is not seen during 
development, their relationship to Cheilanthes, though not close, is none the less a 
reality. And further, since Cheilanthes is not a Pterid-derivative, but is related 
