132 WHERE TO FIND FERNS. 



XLVIII. THE TUNBRIDGE FILMY FERN. 

 Hymenophyllum tunbridgen.se. 

 (Plate XV., Fig. 5, page 77.) 



LENGTH OF FROND. One to six inches, the maxi- 

 mum length being exceptional. 



GENERAL DESCRIPTION. Roots very fine, fibrous, 

 wiry, and abundant. Rootstock, a very slender, hairlike 

 rhiaoma, which branches and creeps extensively, forming 

 oftentimes, with the roots, a dense, matted network, that 

 extends for several yards the interwoven fibres making 

 a mass that may be stripped off like a thick carpet from 

 the surface of the rock upon which they have spread. 

 Fronds evergreen, ovate, and peculiar in conformation. 

 The stipes is brownish-black and hairlike, the rachis 

 continuing it being of similar texture, size, and colour. 

 From each side of the rachis, in alternation, are 

 secondary forked rachides, similar in character to, but 

 somewhat more delicate than, the stipes and primary 

 rachis. The whole of the black, vein-like rachides are 

 margined on either side by semi- pellucid, olive-green, 

 finely-toothed, leaf-like expansions each side-branch or 

 pinna looking somewhat like the spread fingers of a 

 hand. Fructification borne not on the under sides of the 

 leafy parts of the frond, as is the case with the large 

 majority of ferns, but in little cup-shaped indusia, situated 

 upon aborted veins, which branch from the secondary 

 rachides near where these make angles with the main 

 rachis on either side of the latter. The upper margins of 

 the indusia are fringed (see page 18, left-hand figure). 



HABITATS. The damp surfaces of rocks in moist 

 moorland or mountainous country. Hymenophyllum 

 tunbridgense is oftentimes found growing in company 



