274 STUDIES IN FOSSIL BOTANY 



Fucoid Algae, and when found in situ have sometimes 

 been interpreted as epiphytic Hymenophyllaceae. 

 There is, however, no longer any doubt that they 

 formed part of the fronds on which they occur. The 

 Aphlebiae are present in considerable numbers, along 

 the rachis and its branches, in various forms of Spheno- 

 pteris, Pecopteris, Neuropteris, etc. They are common to 

 fronds which were probably those of true Ferns, and to 

 leaves which belonged to Pteridosperms. In some 

 cases the Aphlebiae are entire, orbicular or spathulate, 

 in others they are finely divided in a dichotomous or 

 pinnate manner. They usually differ entirely in form 

 from the normal pinnae of the frond to which they 

 belong, but in some cases transitional conditions have 

 been observed. The position of these organs shows that 

 they are not directly comparable with the stipules of 

 the Marattiaceae ; the best analogy which has been 

 suggested for them is with the feathery outgrowths 

 which occur on the base of the rachis in the recent 

 Cyatheaceous Fern Hemitelia capensis. In this case, 

 as in that of the fossil forms, they were at one time 

 described as independent parasitic Filmy Ferns. 1 M. 

 Zeiller has pointed out that somewhat similar anomalous 

 pinnae are also produced on the rachis of various 

 species of Gleichenia, at the point where the frond 

 resumes its growth after a period of rest. 



2. Fructifications. — We will now endeavour to gain 

 an idea of the nearer affinities of some of the fossils 

 which there are still grounds for referring to the class 



1 See Schenk, " Palajophytologie " (in Zittel's Handbitch der Paltzonto- 

 logie, vol. ii. 1890), p. 141. 



