LIVERWORTS 139 



characteristic of the tribe in general, but they 

 have comparatively few parallels in the foliage 

 of the larger forms of vegetation. Then, too, the 

 finely serrated margin is much less common in 

 the liverworts than it is in the mosses, while the 

 nerve (p. 92), which is present in by far the 

 greater number of moss leaves, is never formed 

 in the leaves of the leafy liverworts, the nearest 

 approach to it, in appearance, being the central 

 line of long, narrow cells in the leaf of the Whitish 

 Liverwort (Diplophyllum albicans, Plate X. fig. 15). 

 But even here there is no true nerve, and little 

 more than a variation in the shape of some of the 

 leaf -cells. 



In not a few of the species, moreover, the leaf 

 consists of two parts, or lobes as they are called, 

 an upper (or antical) lobe, and a lower (or postical) 

 one, a feature to which I have already drawn 

 attention. Pigs. 3, 10, 12, 15, 26, 33, of Plate X. 

 are illustrations of bi-lobed leaves. In some 

 plants the two lobes closely resemble each other 

 in form, though one is usually much the smaller 

 of the two ; in others they are quite dissimilar in 

 appearance, as, for instance, in the Tubercled 

 Liverwort (Frullania dilatata), some leaves of 

 which are given at Plate X. fig. 3; here the 

 small under lobe (it has been drawn uppermost 

 in my illustration in order to show its form more 

 clearly) is hollow, and has a distinct likeness to 

 a small hood or cap, while the larger upper lobe 



