XXXII] 



METAXYA 



289 



irregular (Fig. 552). Their form is flat, and copious long hairs are mixed 

 with the very numerous sporangia. /\part from the sori the mature leaf is 

 destitute of hairs, but the rhizome is permanently covered by a dense brown 

 felt. The hairs are unbranched, and bear no glands. Scales are absent, nor 

 are there any massive emergences or branched hairs, such are seen in 

 Gleichenia pectinata. 



Metaxya has been variously ascribed generically to Polypodium, Aspidinm, 

 Amphidesinium, and Alsophila. Though Presl {Tentatncn, 1836) constituted 

 it a substantive genus, Sir W. Hooker merged it into Alsophila, as A. 

 blechnoides Hk. But this tends to disguise its synthetic nature, and it is best 

 to retain it under Presl's name, as the sole representative of a substantive 

 genus. It will be seen that it takes an interesting place as intermediate 



Fig. 552. Part of a pinna qI Metaxya rostrata Pr. { = Alsophila blechnoides (Ricii.) Hk. ) 

 showing the relation of the sori to the veins. More than one sorus may be borne on 

 a single vein. ( x 2.) 



between the Gleicheniaceae and Cyatheaceae, with suggestions also towards 

 the Matonineae. 



The habit of Aletaxya is always creeping, as in G. pectinata. Sections of 

 the rhizome disclose a distended solenostele, \ an inch in diameter, with 

 voluminous pith, no medullary vascular strands, and no sclerotic bands (see 

 Vol. I, Fig. 149, i). The leaf-trace is undivided, and soon takes the form of 

 a crinkled horse-shoe, while the pinna-traces are of extra-marginal origin. 

 The supply to the branch-rhizomes appears as a diverticulum from the base 

 of the leaf-trace, and it is solenostelic from the first, so that the pith of the 

 branch is continuous with that of the rhizome, as in Lophosoria: this fact 

 suggests unequal dichotomy. The whole vascular system of the leaf including 

 the venation is of a relatively primitive type. The petiolar meristele in 

 G.pectiiiata'\% of a contracted form in accordance with the narrow leaf-stalk, 



B.II 19 



