Hepaticae : Yale Peruvian Expedition of ic)ii. 319 



The postical surface, theoretically at least, bears two low dentate 

 or spinose keels, but these are often coalescent so that only a single 

 median keel appears to be present, and the teeth or spines may be 

 few or absent altogether. 



The male inflorescence in paroicous species occupies a variable 

 length of the fertile branch below the archegonium. The perigon- 

 ial bracts differ scarcely if at all from the ordinary leaves, except 

 for the presence of the single antheridium enclosed within the lobule. 

 The perigonial bracteoles agree in all respects with the underleaves 

 on ordinary vegetative shoots. In autoicous species the male in- 

 florescence occupies a branch of variable length. The bracts are 

 monandrous, closely imbricated, and much smaller than ordinary 

 leaves. The reduction in size affects the lobes most strongly, these 

 being but little larger than the lobules. The bracteoles are likewise 

 smaller than ordinary underleaves and extend the whole length of 

 the inflorescence. 



When compared with the other genera of the Lejeuneae, Dicrano- 

 lejeunea is seen to be especially close to Odontolejeunea, in its restricted 

 sense. ^ In both genera the lobes of the leaves tend to be more or 

 less toothed, although species with entire leaves are included in 

 Dicranolejeunea; in both genera the free margin of the lobule bears 

 one or more teeth, the number being two in all the known species of 

 Dicranolejeune-a and varying from one to four in Odontolejeunea ; 

 in both genera the hyaline papilla of the lobule is situated at the base 

 of the apical tooth on the surface turned toward the lobe; in both 

 genera the leaves lack ocelli, and the leaf-cells have pigmented walls 

 with local thickenings. They agree further in their undivided under- 

 leaves, entire in Dicranolejeunea and either entire or variously toothed 

 in Odontolejeunea ; in the small or obsolete lobules of their perichaetial 

 bracts; and in their compressed perianths with dentate wings on the 

 narrow lateral keels. It is difficult, indeed, to separate the genera 

 by characters which are both constant and significant, although 

 each comprises a group of closely related species. It should be noted, 

 however, that the branching in Odontolejeunea is always of the Radula 

 type, that the subfloral innovations are always single, that the peri- 

 gonial bracts are typically diandrous, and that the radicelliferous 

 discs on the underleaves are well developed. In Dicranolejeunea 

 both the Radula and the Frullania types of branching occur, the sub- 

 floral innovations are typically in pairs, the perigonial bracts seem to 

 be constantly monandrous, and the radicelliferous discs are either 



1 See Evans, Bull. Torrey Club 31 : 183. 1904. 



