56 DESCRIPTIONS OF N.Z. FERNS. 



the frond being called again pinnate, particularly as these farther divisions are them- 

 selves pretty deeply lobed. The sori are terminal on some of the lower lobes ; but as 

 there is usually a longer lobe than the fertile one immediately outside of it, the sori, at 

 first sight, appear axillary ; and though they are numerous, they seem confined to the 

 lower portions and sides of the pinnules, and never occur on the terminal lobes. The 

 involucres consist of two valves of an oval form and moderate size ; but the receptacle 

 soon protrudes far beyond them, bearing elongated oval masses of capsules, often 

 three or four times the size of the involucres. This fern, which is a strikingly hand- 

 some one, is peculiar to New Zealand, but has only been found from about Auckland 

 northwards. It grows in light bush or high scrub, and on hill-sides or terraces, rather 

 than in the bottoms of gullies ; and when shaken by the wind, looks particularly 

 beautiful, owing to the different colour of its upper and under-surfaces, as they 

 alternately show and disappear wave-like. The colour of the under-surface seems to 

 vary with the season of the year, though it is whiter in some localities than in others. 

 It is not difficult to grow, if the plants are procured while young; but it will not stand 

 frost, and it spreads so rapidly as not to be well suited to pot-culture. Leaf-mould 

 over clay, with moderate moisture, are its natural conditions. This fern is specially 

 interesting on account of its being apparently a survivor from an extremely remote 

 past. It is far more closely allied than any other now existing to the Palaeopteris 

 Hibernica, a fossil fern found in the Devonian rocks, and the most ancient land plant 

 of which the remains have come down to us in a sufficiently perfect form to be capable 

 of identification. In the same strata are found fragments of what appear to be 

 Hymenophylla, indicating that the filmy ferns were among the earliest plants that 

 grew on dry land, though some seaweeds seem to have preceded them. 



GENUS HYMENOPHYLLUM. (Hy-men-o-fil-lum.) 



" FILMY FERNS." 



From Greek hymen, a film ; phyllon, a leaf. Has the sori marginal, more or less 

 sunk in the frond or exserted, terminating a costa or vein. Involucres beneath sorus, 

 more or less deeply two-lipped or two-valved, of nearly same texture as the frond, 

 toothed, entire, or fringed. Receptacle elongated, usually cylindrical, inserted or 

 exserted. Capsules mostly orbicular, depressed, attached by the centre ; furnished 

 with broad transverse ring, opening irregularly at the top. Fronds generally mem- 

 branous in texture, costate, or with simple or forked veins only. This genus divides 

 into several classes, according to peculiarities of the fronds, and this facilitates 

 classification. First, there are plants with entire edges, one to four times pinnatifid 

 some of which again have wings on the rachis only, while in others the wings extend 

 down the stipes also. Of the former the following are the plants generally recognised 

 as belonging to New Zealand and its immediate dependencies. 



