20 Evans : Hepaticae of Puerto Rico 



The species belonging to this genus are nearly all robust and 

 vary in color from dull-green to glaucous or whitish-green. They 

 are never glossy and many of them become brownish with age or 

 upon drying. The prostrate stems are more or less closely ad- 

 herent to the substratum and branch irregularly ; some of the 

 branches are similar to the stem, but they are more often short 

 and limited in growth, and in certain species microphyllout 

 branches are to be observed. The leaves are closely imbricated 

 (plate 2, figure 9). The lobes are convex and falcate, although 

 sometimes in a very slight degree ; they vary in shape from 

 ovate to subrotund ; the apex is broad and rounded, and the 

 margin varies from entire to minutely crenulate. The leaf-cells 

 are more or less convex ; their walls are firm, sometimes with dis- 

 tinct trigones (figure 13), sometimes presenting the appearance of 

 being uniformly thickened. Ocelli occur in many species, but not 

 in all ; they are sometimes scattered (figures 9, 10), but are usu- 

 ally at the base of the lobe. The lobule varies in outline from 

 broadly ovate to long-rectangular and is built up on the same plan 

 as in Rectolejennea, with the hyaline papilla proximal in position. 

 The underleaves are closely imbricated ; they are nearly always 

 orbicular in general outline, but are sometimes broader than long ; 

 they are bifid with pointed divisions, and their margins are com- 

 monly entire. 



The female branch is variable in length, but is usually long. 

 The flowers innovate on one or on both sides, the innovations 

 themselves being often again floriferous. The bracts are about as 

 large as the leaves on robust and sterile axes, but are larger than 

 the leaves which immediately precede them on the female branch. 

 They are unequally bifid and usually distinctly complicate, in many 

 cases showing a narrow and entire wing along the keel (figures 19, 

 20). The lobe is broad and rounded, and the narrow lobule varies 

 from acute to rounded even on a single specimen. The bracteole 

 is larger than the underleaves and less deeply bifid. The perianth 

 is obovate in outline and is sharply five-keeled, at least in the 

 upper part (figures 9, 21, 22). The apex is broad and usually 

 rounded, the beak being short but distinct. The antheridial spike 

 usually occupies a short branch (figure 23), but is sometimes terminal 

 on a longer branch ; the antheridia, so far as observed, occur in 

 pairs. 



