12 Evans : Hepaticae of Puerto Rico 



fications. In the first place, they lose largely, if not entirely, the 

 power of developing rhizoids. In the second place, the lateral 

 teeth, which are sometimes vaguely indicated on normal under- 

 leaves, become very distinct, often attaining a length of three cells 

 and a width of two cells at the base. In the third place the prin- 

 cipal divisions become sharply pointed, usually ending in a row of 

 from two to four cells, and the sinus becomes broad and lunulate 



(figure 25). 



The leaves which precede the modified leaves exhibit transi- 

 tional characters. They tend to become more pointed, scattered 

 marginal cells grow out into rhizoidal processes or even into short 

 teeth, and the lobule becomes smaller and more rudimentary. 

 It is interesting to note that a branch which bears these transitional 

 leaves sometimes recovers from the tendency to become flagelli- 

 form and continues its growth normally. In one case, for ex- 

 ample, the proliferation of an antheridial spike developed first a nor- 

 mal leaf, then a series of transitional leaves, then a second anther- 

 idial spike. It is also probable that the dentate or ciliate bracts 

 and bracteoles, which are occasionally to be observed on a female 

 inflorescence, represent similar transitional conditions. In these 

 cases the development of the archegonium, of course, terminates 

 the elongation of the branch ; but in one observed instance the 

 innovation from a flower of this character became flagelliform 

 almost immediately, showing that the tendency toward such de- 

 velopment was present in a marked degree. 



Rectolejeunea Berteroana (Gottsche) 



Lejennea (Odontolejeuned) Berteroana Gottsche in Stephani, Hed- 

 wigia 27: 282. pi. n, f. 6. 1888. 



Lejeunea versifolia Gottsche in Wright, Hep. Cubenses (with- 

 out description); Schiffner, Bot Jahrb. 23: 597. 1897 (as 



synonym). 

 Cheilolejeitna versifolia Schiffn. /. c. pi. 5, f. 1—7. 



On bark of trees. Puerto Rico, Bertero, the type locality. 

 The species is also known from Cuba ( Wright), from southern 

 Florida (Underwood), and from the Bahamas {Mrs. Britton). 



R. Berteroana and the preceding species are very closely 

 related. They agree in the shape of their leaves and underleaves, 



