444 Bower . — Studies in the Phytogeny of the Filicales. 
shows that cross relations exist, and suggests that it may be a synthetic type. 
It had been variously ascribed to Polypodium , Aspidium , Alsophila , and 
Amphidesmium before Presl placed it in a substantive genus by itself. 
Sir William Hooker introduced it as a substantive genus into his ‘Genera 
Filicum ’, and figured it on his Plate XLII, B. It is noted as a very hand- 
some genus of South American Ferns, allied in habit to Trichopteris. But 
in his ‘ Species Filicum ’ (vol. i, p. 35) he places Metaxya as a sub-genus of 
Alsophila\ while later, in the ‘Synopsis Filicum’, it is no longer dis- 
tinguished as a sub-genus, but is merged into Alsophila , appearing as its 
first species. Sir William Hooker thus took three successive steps in his 
treatment of the Fern. First, he accepted it as a valid genus (Gen. Fil.), 
then he reduced it to a sub-genus (Sp. Fil.), and finally he merged it in 
Alsophila (Syn. Fil.). Diels (Engler u. Prantl, i. 4, p. 132) adopts the 
middle position of Hooker. Christ (‘ Farnkrauter/ p. 324) places it also as 
the first species of Alsophila , under the sub-genus Amphidesmium , Shott. 
A more divergent position is, however, taken by Grisebach (‘ Flora of the 
British W. Indian Islands,’ p. 697), who places it in Polypodium § Phegopteris. 
It will be shown that a more exact examination of its details will tend to 
support the original position of Presl, and to uphold Metaxya as a genus 
distinct from Alsophila , and occupying an interesting position phyletically, 
which well justifies his old name for it. 
The single species, Metaxya rostrata , is an inhabitant of Tropical 
America, and is well represented in herbaria. From inspection of dry 
specimens few would doubt that it is correctly given a place in relation to the 
Cyatheaceae, and especially with Alsophila. But to form an opinion on its true 
phyletic relation to these Ferns and others, it is desirable to make a revision 
of its details, anatomical and developmental, for which material properly 
preserved is necessary. This was kindly supplied by Mr. Stockdale, from 
British Guiana, and to him my best thanks are accordingly due. 
It is a large handsome F'ern, with creeping rhizome and leaves a metre 
long. These are borne in close succession, so that they may sometimes form 
a sort of terminal crown. The leaves are singly pinnate, with a hard smooth, 
dark-coloured rachis, while the numerous large pinnae are lanceolate, and 
slightly serrate at the tip ; but lower down the margin is entire. The veins 
run parallel outwards from the thickened midrib, and are only occasionally 
forked. The internodes of the creeping axis vary in length. Branches are 
from time to time formed in relation to the leaf-bases. The bud appears 
on the abaxial side, and in the median plane of the leaf. In fact their 
position relative to the leaf is the same as in Lophosoria. Further, the pith 
of the bud (which as will be seen later is solenostelic) is continuous here 
also with that of the axis ; that is, the solenostele inserts itself without 
closing upon the abaxial side of the undivided leaf-trace, as in Lophosoria. 
At a short distance out from the midrib are the sori, and as one is 
