84 



BRITISH FERNS. 



The veins proceed directly from tlie rachis, and each has four 

 or five branches : to the outside branches of each vein, or set of 

 veins, is attached an elongate linear mass of thecse, and this mass 

 is covered by a white membranous indusium of the same form. 

 Owing to this disposition of the thecae on the outer branch, the 

 masses are invariably in pairs ; the two indusia at first touch and 

 appear as one, a day or two later a line appears between them 

 shewing that they are divided ; the line gradually becomes 

 more apparent as the thecae increase in size ; at last, the two 

 indusia are pushed back from each other, and finally disappear. 

 The veins and attachment of thecae are shewn on the upper 

 side of the figure at page 82 ; the indusia and masses on the 

 lower side : the earliest stage of the double mass and its indusia 

 is shewn to the right hand, and each successive figure towards the 

 left shews a gradual advance towards maturity. The length of 

 the mass is very inconstant. 



Gerard mentions a plant under the name Hemionitis sterilis, 

 " which is a very small and base herb, not above a finger high, 

 having four or five small leaves, and of the same substance and 

 colour, spotted on the back part, and like unto Hart's -Tongue, 

 found in a gravelly lane in the way leading to Oxey Park, near 

 Watford, fifteen miles from London, also on the wall at Hampton 

 Court.'' This plant must, I think, be referred to the present 

 species. 



