XLVII] COMPARISON 247 



Vittaria zx\<^ Monogramme, which also have Hnear sori. But Antrophyiim, 

 with its reticulate sori, would be more advanced, and Anetium, with its 

 Acrostichoid sporophyll, would be the most advanced of the whole Family. 

 It may probably be remarked that the vascular system accords ill with this 

 conclusion: but the protostelic axis and undivided leaf-trace are juvenile 

 features common to all sporelings. These the dwarfed Hecistopteris does not 

 exchange for a more elaborate system such as appears in the adults of 

 the larger genera: therefore a full anatomical comparison with them is 

 impossible. 



With Hecistopteris thus indicated as a relatively primitive type among 

 this coherent group of genera, the question of the phyletic relations as a 

 whole may be considered afresh. The instinct of Sprengel (1828) was 



Fig. 746. ^-^=)uvenile leaves oi Antrophyum lineatiim. 7^-7=juvenile aiK 

 fertile leaves of Hecistopteris piunila. (After Williams.) 



probably quite correct in assigning to Hecistopteris a relationship with 

 Gymnogravniie, under his original name of G.pitmila. But J. Smith {Historia 

 Filicum, 1875, p. 178), finding that it did not appear to form a natural 

 alliance with any section of that genus, gave to Hecistopteris generic rank. 

 Now it may be held as a natural link connecting the Gymnogrammoid 

 Ferns with the Vittarieae. The peculiarities which specially characterise 

 these Ferns are probably consequences of habit : in fact the Vittarieae may 

 be held to represent an epiphytic and rupicolous branch of specialisation 

 from a Gymnogrammoid source. The most peculiar structural feature that 

 is common to both Families is the spicular cells, which have been seen to 

 recur in Adiantum, a Gymnogrammoid genus itself specialised along lines 

 quite distinct. It would, however, be an error on the ground of this detail to 

 press any close relation to the epiphytic types. But it may legitimately be 



