156 Evans: Hepaticae of Puerto Rico 



plants the lobes are suberect and wrapped around the stem, but as 

 soon as they become moistened they spread widely (plate 6, fig- 



) 



The change 



in appearance is very similar to what is found in the genus Masti- 

 golejennea. The lobes are approximately ovate in outline and vary 

 at the apex from rounded to apiculate or acute. The margin is 

 usually entire, but, in certain species, tends to be slightly serrulate 

 in the neighborhood of a female inflorescence. The lobule is 

 relatively large and consists of two distinct portions approximately 

 equal in size (figures i, 2). One of these occupies the carinal 

 region and takes part in the formation of a conspicuous water-sac, 

 usually about half as long as the lobe. The other is bounded by 

 the free margin and is closely appressed to the lobe except at the 

 apical sinus where an opening into the sac is to be observed. The 

 appressed portion of the free margin bears a series of teeth from 

 three to ten in number. These teeth vary greatly in size and in 

 form (figures 7-9), but in the majority of cases each tooth is sev- 

 eral cells long and so strongly curved toward the lobe that it can- 

 not be straightened out even by pressure on the cover-glass (fig- 

 ure 12). The outermost tooth, which represents the apex of the 

 lobule, varies from a single projecting cell to a broad and rounded 

 projection (figures 10, 11). The hyaline papilla is borne at the 

 proximal base of this tooth but is displaced to the inner surface of 

 the lobule, usually appearing two or three cells from the margin. 

 Beyond the apical tooth the long and shallow sinus extends, form- 

 ing a very acute angle with the outer part of the keel. The latter 

 is more or less arched near the base but tends to be incurved where 

 it meets the postical margin of the lobe. The leaf-cells have thin 

 walls but distinct trigones (figure 6). These are usually triangu- 

 lar in outline, two of the sides being convex and one concave. 



1 



The thin places between the trigones are relatively wide and rarely 

 develop intermediate thickenings. 



The undivided underleaves are rotund to reniform in outline 

 and are attached by an arched line (figure i). In certain species 

 they are distinctly auriculate at the base (figure 14); in others 

 they are rounded or even cuneate. The margins are sometimes 

 plane and sometimes more or less revolute ; they vary from entire 

 to irregularly sinuate but are never distinctly toothed. 



