XL] STONEWORTS, AND PEPPERWORTS. 171 



off a number of erect, tapering leaves from four 

 to six inches in length. These leaves consist of four 

 rows of long cells placed side by side, and subdivided 

 by transverse partitions. It is these transverse parti- 

 tions which show through the epidermis and give the 

 leaf the jointed appearance shown in fig. 129. The 



FIG. 130. 



FIG. 131. 



FIG. 129. 



base of the leaf is very broad, and concave ; within 

 the hollow it bears the fructification, which is of two 

 kinds. The spore-cases produced by the outer leaves 

 contain large four-sided spores which open on the 

 upper surface by three triangular valves ; whilst those 

 of the inner leaves are minute and more numerous. 



