146 FILICES. 



in number, they form a simple circle and are laterally in contact with one 

 another ; when there are more of them, as in Oligocarpia Brongniartii, we 

 find a central group of two or three sporangia surrounded by a simple 

 outer circle. They are attached to the expanded receptacle by a broad 

 flat basal surface ; they are obliquely pyramidal in shape and incline towards 

 one another and towards the middle of the sorus. Stur is of opinion that 

 the place of dehiscence may be seen in the form of a pore at the obtuse 

 apex ; at all events a gaping lateral slit has never been observed in any of 

 the numerous specimens which have been examined. The stout wall, at 

 least in the upper pyramid-shaped portion, is formed of large polygonal 

 very thick-walled cells, which are developed however in a similar manner 

 all round, so that no proper annulus can be distinguished. Goppert had 

 already credited his Oligocarpia Gutbieri with a well-developed annulus, 

 which he compared with that of Polypodiae ; Zeiller subsequently re- 

 affirmed its existence and described it as an ' annulus transversalis,' and thus 

 the genus came to be placed among Gleicheniaceae. By the kindness of 

 the latter author I have had the opportunity of seeing his specimens, and I 

 am still obliged to assent to Stur's denial of the independent existence of 

 this annulus. If we look at the obliquely conical sporangium from above, we 

 get a profile view of one or more transverse rows of the strongly thickened 

 cell-walls, and may mistake them for an annulus ; but we find that when- 

 ever we alter the position of a detached sporangium, the supposed annulus 

 appears in another place. Stur is right in his remark that Zeiller's figures 

 do in fact show this, and that the ring appears in them in a different position 

 according as the sporangia are seen from above, or in the side-view. 



Stur's account of his genera Discopteris and Saccopteris, which he 

 would refer to this place, is not so convincing as that of Hawlea and 

 Oligocarpia. Discopteris, which includes various Sphenopteridae, &c.,from 

 the Coal-measures, as Sphenopteris Goldenbergii, Andrae, S. Coemansi, 

 Andrae, has round sori formed of a large number of sporangia (70-100). 

 The sporangia are very small and have a ' superficies reticulato-areolata.' 

 Zeiller * compares his Myriotheca with Discopteris ; but in Myriotheca, 

 according to the description, the free ovoid sporangia which resemble those 

 of Marattiaceae cover the whole under surface of the leaf without forming 

 distinct sori, somewhat after the manner of Acrostichum. Saccopteris, 

 Stur, is composed of forms from the Coal-measures, which by their nerva- 

 tion belong to Pecopteris, Alethopteris, and Sphenopteris. Its sori, placed 

 in two rows on the pinnae, are circular in shape and are formed of numerous 

 irregularly disposed elliptical sporangia, which are attached by a narrow 

 base and open on the inner side towards the apex by a pore with a steep 

 border. Stur endeavours to show that Zeiller has described under the name 



1 Zeiller (6). 



