ClATHKOPTEEIS. 17 



Class FILICALE8. 



Pamily DIPTERIDIjSTiE. 



In my former volume on Jurassic plants this family-name was 

 used to include such, fossil genera as Bictyophyllum, Protorhipis, 

 Clathropteris, and others, as well as the four existing species of the 

 genus Bipteris, an Indian and Malayan type, which have heen 

 placed in a separate family — Dipteridinae — on account of certain 

 peculiarities which distinguish it from the true Polypodia oese.' 



Genus CLATHROPTERIS, Brongniart. 

 [Prodi-omfe, p. 62, 1828.] 



This genus was instituted hy Brongniart in 1828 for a plant 

 which he had previously'' described from the Rhsetic rooks of 

 Scania as Filicites meniscoides. The most striking characteristics 

 are the pinnatifid fronds and the regular rectangular meshes 

 formed by the finer veins in the lamina. The best known species 

 of the genus is Clathropteris platyphylla (Gopp.), of Ehsetic age, 

 the same type which Brongniart described in 1825 as Filicites 

 meniscoides. Clathropteris fronds bear a close resemblance to those 

 of Bictyophyllum, a genus which is abundantly represented in the 

 Inferior Oolite flora of Yorkshire, and is a prominent member of 

 the Ehsetic floras of Scania and other regions. As I have 

 elsewhere pointed out, the main distinction between the two 

 genera consists in the more regular and rectangular form of the 

 meshes,' formed by the secondary and tertiary veins, in the lamina 

 of Clathropteris. In all probability the two names have been 

 applied to ferns that are generioally identical, and it would 

 probably be more in accordance with the facts of relationship if 

 we absorbed Clathropteris into Bictyophyllum. It has, however, 

 long been customary to make use of both generic names, and as 

 a matter of convenience we may in this instance retain the 

 generic designation Clathropteris. 



' For an account of the DipteridinsB, see Se-ward & Dale (01) ; see also 

 Seward (OS'). 



2 Brongniart (25), p. 207, pi. xi. 



