560 FILICALES 
primitive. It will be seen that this species has a stelar structure of the axis 
of a type which also indicates its relatively primitive character in the genus. 
The sorus of O/igocarpia from the upper Carboniferous corresponds 
in its arrangement to that of Gleichenia (Fig. 312). O. Gutbiert and 
lindsaeoides show uniseriate sori with varying number of the sporangia, 
as in G. flabellata; but O. Brongniartit has accessory sporangia occupying 
B 
mM, 
Ce % 
sepa 
Gann 
af 
aes 
Fic. 312. 
I. Otigocarpia Brongniartii, Stur. A=asterile ; B=a fertile pinnule (#); C=a sorus 
more strongly magnified. (After Stur.) II.=two sori of the same species. X35. (After 
Zeiller.) ILI. Oligoce¥®pia Gutbieri, Gdpp. _A=position of the sori on a segment of 
the last order. X30. A=asorus. X60. (After Stur.) IV.=Oligocarpia lindsaeoides 
(Ett.), Stur. A=position of the sori on a segment of the last order. x30. =a sorus. 
C=asporangium. X60. (After Stur, from Potonié’s Lehrbuch.) 
the centre of the sorus, as in G. dichotoma. There is, however, a difference 
of opinion as to the annulus, and it is upon this that the ultimate deter- 
mination must rest: Zeiller recognises an annulus similar to that of the 
Gleicheniaceae; but Solms Laubach! does not assent to this, asserting 
that the supposed annulus is due to an effect of lighting of the specimen 
under observation. Zeiller nevertheless adheres to his opinion.2. Whatever 
1 Fossil Botany, p. 146. 
2Potonié, Lehrbuch, p. 102. Mr. Kidston has shown me specimens of Oligocarpia 
Gutter? in which the line of dehiscence was clearly seen running radially down the 
central face of the sporangium. The annulus could not be reduced to a single row of 
cells. Probably the type had a pluriseriate annulus like other Palaeozoic Ferns (compare 
Kidston, PAz2. Trans., Ser. B, vol. 198, p. 188; also Scott, Progressus Rei Botanicae, 
vol. i., p. 184). It may, however, be remarked that a division of the cells of the annulus 
appears as an occasional irregularity in sporangia of living species of Glecchenda, a distant 
suggestion of a pluriseriate annulus in the ancestry. 
