ATIIYRIU.M. 125 



selves. The liippocrepiform soms is formed by the lateral 

 line of spore-cases crossing the vein and returning on the 

 opposite side ; sometimes in the case of the curved, or 

 horseshoe-shaped sori, the indusium is apparently almost 

 circular, with a lateral notch, and in this state the 

 fructification somewhat resembles that of Lastrea. One 

 side of the indusium is fixed longitudinally to the side of 

 the vein which forms the receptacle ; its other margin, the 

 anterior one, or that towards the midvein of the pinnule, 

 becomes free, and is fringed, or split into a number of 

 hair-like segments. This description applies to the com- 

 moner forms of the Lady Fern ; but even these are very 

 variable in size, according to the situation and circum- 

 stances which influence their development, sometimes 

 scarcely exceeding a foot in height, and at other times 

 reaching the height of four or five feet, the latter being 

 the result of growth in a damp, shady situation, the former 

 the consequence of a more exposed and drier locality. 



The variety rhseticum, sometimes called convexnm, 

 differs from the forms already described in its more lad}^- 

 like proportions, both its fronds, its pinnae, and its 

 pinnules being often smaller and usually more slender and 

 narrower, or narrower-looking, than in them. The fronds 



