XXVII I] 



COMPARISON 



25; 



excellent drawing for Loxsouia (^Fig. 525). It has the usual cordate form, but 

 it is notable that when old it may bear on its lower surface bristles with 

 distended base, similar to those on the rhizome. Von Goebel compares 

 these with those of the Cyatheaceae (inch Dicksonieae), Since in Loxsoma 

 the appendages are of the nature of bristles and not actually flattened 

 ramenta, their presence does not appear to be decisive as to phyletic 

 relationship. Moreover, it is not uncommon to find the same type of 

 appendages on both generations in Ferns (Vol. I, p. 198, Fig. 185), The 



Fig. 525. a, prothallus o{ Loxsoma seen from below. (Enlarged.) i'^appendages described by von 

 Goebel as "schuppenhaare" : y^ =archegonia. b, apical groove of a prothallus oi Loxsoma, more 

 highly enlarged than [a], and showing the bristle-like hairs, E is the leaf of a sporeling. (After 

 von Goebel.) 



Structure of the antheridium of Loxsoma does not differ essentially from 

 that of the Polypodiaceae. Thus the gametophyte does not greatly help in 

 establishing phyletic relations (see below, p. 267). 



Comparison 

 The Loxsomaceae appear as a generalised type of Ferns. In habit and 

 anatomy they resemble the Dicksonia-Dcnnstaedtia series, with which also 

 the marginal position of their sorus and their dermal appendages agree, 

 while the sporangium of Loxsomopsis is very like that of Thyrsopteris, or of 

 a short-stalked type of Dicksonia. On the other hand there is a general 

 similarit)' to the sorus and sporangia of the Hymenophyllaceae, though the 

 spore-output is lower than that of their more robust forms. The indusial 

 protections of the Schizaeaceae show a general but not a close analogy, as 

 also do the sporangia of Aiiemia. It seems reasonable to contemplate an 

 origin from some Schizaeoid source. But the sorus of the Loxsomaceae is 

 B. II 17 



