488 Boodle.—Anatomy of the Hymenophyllaceae. 
{ The leaf-trace [in Trichomanes\ gives off the stele of the 
axillary branch precisely in the same manner as in Zygopteris , 
the resemblance extending even to details.’ This is seen by 
comparing figures of Zygopteris scandens , Stenz. 1 , with the 
diagrams of the node of T. radicans. The following facts are 
taken from Scott’s work quoted above 2 . In Zygopteris the wood 
in section has the outline of an irregular five-rayed star, the 
five rays corresponding with the orthostichies of a two-fifths 
phyllotaxis. In the wood there is a central five-rayed tissue 
(of parenchyma including small tracheides) covered by a peri¬ 
pheral zone composed mostly of large scalariform tracheides 
but with smaller tracheides at the ends of the arms. The leaf- 
trace passes off as a closed ring of tracheides enclosing central 
parenchyma and small tracheides. In comparing the above 
structure with the Hymenophyllaceae, if the small central 
tracheides are protoxylem, the agreement with Trichomanes 
reniforme or the larger Hymenophyllums is very close, the dif¬ 
ference being such as would be due to a two-fifth arrangement 
on the one hand and distichous on the other. The annular 
xylem of the base of the leaf-trace also agrees with T. reniforme . 
Botryopteris has a solid xylem-mass (consisting of tracheides 
only) in its stem. The Botryopterideae mentioned are found 
in the Coal-Measures and Permian. The sporangia of neither 
genus agree with the Hymenophyllaceae as to their annulus, 
therefore close affinity cannot be affirmed ; but quite possibly 
Botryopteridean structure may have been shared by the 
members of a rather large generalized group, from some of 
which the Hymenophyllaceae have been derived. 
In Botryopteris forensis ‘ the tissue of the leaf appears to 
have been fleshy ; on the one surface numerous stomata were 
present V Thus fossil plants occur which resemble the 
Hymenophyllaceae (more than any living Ferns do) in several 
structural points, but were not filmy ; i. e. the only fossil 
evidence (not very weighty, it is true), does not support the 
1 Stenzel, Die Gattung Tubicaulis, Bibliotheca Botanica, Cassel, 1889, Taf. VII, 
Figs, 60, 61, 65. 
2 Scott, 1 . c., p. 280 et seq. 
Renault, cited by Scott, 1 . c., p. 294. 
