THE ONE-SIDED FILMY FERN. 135 



intimately mixed with roots of moss, and of its con 

 gener, the Tunbridge Filmy Fern. Fronds evergreen, 

 elongated, oval in shape ; stipes and rachis brownish- 

 black ; leafy part olive-green, bipinnate ; pinnae opposite 

 or alternate, divided into elongated, narrow pinnules, 

 which arise from one side and that the upper of the 

 midvein of each pinna. The texture of the fronds is of 

 the same semi-pellucid nature as that of the fronds of 

 Hymenophyllum tunbridgense, and they have the appear- 

 ance as of winged leafy margins to a series of forked 

 veins, the distinction between the two species con- 

 sisting in the fact that the pinnules of Hymenophyllum 

 unilaterale, besides being wider apart from each other, 

 are produced upon one side only of the pinnae, and not 

 on both as is the case in Hymenophyllum tunbridgense. 

 Fructification produced in urn-shaped indusia similar to 

 those of the Tunbridge Filmy Fern, but entire, instead 

 of being fringed upon their upper margins the indusia 

 being situated upon aborted veins that branch from the 

 pinnae on each side of and near the junction of the latter 

 with the main rachis (see page 18, right-hand figure). 



HABITATS. Exactly similar to those indicated in the 

 case of Hymenophyllum tunbridgense^ namely, damp, 

 shady rocks, tree-trunks, and the ground, oftentimes 

 keeping company with that species, and with moss, the 

 roots and rhizomas interlacing with the mossy roots and 

 stems. 



WHERE FOUND. In England, in the counties of 

 Cornwall, Cumberland, Devon, Kent, Lancaster, Salop, 

 Stafford, Westmoreland, and York. The following are the 

 localities of these counties : In Cornwall, the vicinity 

 of Bodmin, Rough Tor (near Camelford), Granite Tor, 

 and Cam Brea (near Redruth). In the county of Cum- 

 berland, Borrowdale, Bow Fell, Scale Force (near Butter- 

 mere), Dalegarth, Ennerdale, Gatesgarth Dale, High 

 Still, Honister Crag, Keswick, and Lodore Fall. In 

 Devonshire, Bickleigh Wood, Moreton Hampstead, 



