FILICES. 



by the presence in their wall of an apical group of abnormally thick-walled 

 cells which extend some way down on the outer side of the sporangium ; 

 these cells have quite the appearance of an annulus, and are moreover 

 developed at the spot where the 

 rudiment of the annulus is seen to 

 arise in Angiopteris. 



Another group is that of the 

 Hawleeae, which differ from Astero- 

 theceae in having free non-coherent 

 sporangia, but agree with them in 

 the circular form of their sori. The 

 genus Hawlea 1 , originally founded 

 on a small fragment of a leaf from the 

 Coal-measures of Svina in Bohemia, 

 has been enriched by Stur with many 

 species which appear in the older 

 literature as Pecopteris, for example 

 Pecopteris Miltoni, Germ., P. crenata, 

 Stbg, P. Bucklandi, Ldl. and Hutt.(not 

 Brongn.). To this genus also he refers 

 the remains described by Zeiller 2 as 

 Calymmatotheca, which he contends 

 do not belong to the genus of that 

 name. The sporangia in Hawlea are 

 sessile and elongate-ovoid in form, 

 and spread out from one another in 

 all directions, so that the dehiscence- 

 slit on the inner side is directed 



straight upwards and the sporangium 



when open has the form of a boat. 



The sori on the back of the tertiary 



nerves form a single row on each side 



of the secondary nerve. Oligocarpia, 



Gopp. (Fig. 13, C} is distinguished 



from Hawlea chiefly by the character 



and disposition of the sporangia ; 



the two forms agree in the circular 



shape and arrangement of the sori. 



Oligocarpia Gutbieri 3 was the species 



first described, and Stur has included in it several other forms from the 



Coal-measures. If the sporangia in the sorus of the Oligocarpiae are few 



FIG. 13. Fructifications of fossil Marattiaceae from the 

 Carboniferous formation. A Senftenbergia ophiderma- 

 tica ; to the left the position of the sporangia on both 

 sides of the median nerve of the pinnule, to the right a 

 single sporangium seen from above. B Hawlea Miltoni ; 

 to the left pinnae with the sori on the extremities of the 

 lateral nerves, to the right a single sorus more highly 

 magnified. C Oligocarpia lindsaepides, showing position 

 of the few-membered circular sori on the nerves of the 

 pinnule. D Scolecopteris polymorpha, Brongn. ; to the 

 right a pinnule showing the position of the sori in trans- 

 verse section, to the left a longitudinal section of a sorus 

 in which the sporangia are grown together below into a 

 columnar receptacle. E Asterotheca Sternbergii ; to the 

 right the pinnule with sori, to the left a side-view of a 

 sorus and a sorus in radial section. D and E diagram - 

 matically represented. All the figures after Stur. 



1 Corda (1), t. 57, ff. 7-8. 



2 Zeiller (7). 

 L 



Gbppert (1), i and 2, t. 4. f. 12. 



