Evans : Hepaticae of Puerto Rico 23 



The characters which separate P. Schwaneckei from the closely 

 related P. macroloba are tabulated by Stephani, and little of 

 importance has since been written on either species. Schwanecke's 

 original material represents a somewhat laxer form than most of 

 the specimens recently collected, although connected with them 

 by intergrading conditions. If well -developed forms of the species 

 are compared with typical P. macroloba, it will be found that some 

 of the differential characters relied upon by Stephani are incon- 

 stant. The plants, for example, are equally robust in the two 

 species, and the texture of P. Schwaneckei is really the denser of 

 the two ; there is but little difference in the branching ; the leaves 

 in both species are strongly imbricated, and the same is true of 

 the underleaves ; the leaf-cells do not show the differences which 

 are ascribed to them, and there is no constant difference in the 

 position of the antheridial spike. The other differential characters 

 which Stephani notes seem to be trustworthy. The inflorescence 

 in P. Schwaneckei, as he remarks, seems to be always dioicous, while 

 in P. macroloba, the inflorescence is normally autoicous, although 

 unisexual individuals sometimes occur. The keel of the leaves in 

 P. macroloba is nearly always distinctly arched, and the postical 

 margin of the lobe, where the free margin of the lobule meets it, 

 is plane or nearly so, although the apex of the lobe tends to be 

 revolute. In P. Schwaneckei the keel is straight, and the lobe is 

 revolute along the postical margin as well as at the apex. The 

 underleaves of P. macroloba, also, are more deeply bifid, and their 

 divisions are usually more acute. 



In addition to these differences, it may be noted that the leaf- 

 cells in P. macroloba are a trifle larger than in the other species^ 

 averaging 25// in the middle of the lobe. The local thickenings 

 in the cell-walls are about the same size, but appear more distinct 

 because separated from one another by broader pits and showing 

 much less tendency to become confluent. The ocelli, also, are 

 fewer, only two to four, and less distinct. According to Schiffner,* 

 the cell-walls in P. Schwaneckei are uniformly thickened, an ap- 



*Lebermoose der Forschungreise S. M. S. Gazelle, 32. 1890. The species is 

 here recorded from the island of Amboina, but apparently through error, since Schiff- 

 ner makes no mention of it in his Conspect. Hepat. Archip. Indici, published in 

 1808. 



