THE RUE-LEAVED SPLEENWOET 75 



ularly-toothed. The venation consists of a series of 

 veins repeatedly forked from the base, so that there 

 is no distinct midvein. ; the number of the venules 

 corresponds with the number of marginal teeth. 

 Several sori are produced near the centre of the pinna, 

 covered by indusia opening inwardly with a jagged 

 or irregularly-sinuated margin. The plant is ever- 

 green and easy of cultivation. It is so common that 

 there is no occasion to give any special habitats. It 

 extends to about 600 feet above the sea-line. 



In its normal conditions A. Huta-muraria is easily 

 recognizable : the characters afforded by its triangular 

 (deltoid) outline, bipinnate or tripinnate division, and 

 distinct wedge-shaped pinnules, together with the 

 smallness of the fronds, sufficiently distinguishing it 

 from the other Aspleniums. There are, however, cer- 

 tain of its forms which are not, at first sight, so easily 

 separated from A. germanicum, being narrow on the 

 fronds or pinnules, and sometimes scarcely more than 

 pinnate. These forms are best distinguished by the 

 round-toothed (crenulate) indusia, and by the fine 

 even toothing of the anterior margin, the indusium 

 in A. germanicum being entire, and the apex of its 

 pinnules being less deeply and unequally notched. 



VARIETIES. 



cristatum, Farleton Knott, Wollaston. 



unilaterale, Troutbeck, Miss Wright ; Kendal Fell, J. M. 



Barnes. 



cuneatum, Sizergh, J. Crossfield. 

 ramosum, Silverdale, J. Crossfield. 



