The Genus Riccardia in Chile. 185 



indentation. The developed vegetative branches vary greatly. 

 Some of them are suberect or obliquely spreading and essentially 

 like the axis, approaching or even equaling it in width and showing 

 long-continued growth. Others are shorter and quickly limited 

 in their growth. These shorter branches rarely exceed 5 mm. in 

 length and are mostly 0.2-0.6 mm. broad. They may be simple or 

 sparingly subdivided, and their branches or even their apices are 

 sometimes in the form of stolons, directed more or less backward. 

 The stolons are perhaps 0.3 mm. wide and 0.18 mm. thick. 

 Although the cells are smaller than those of the axis, there is still 

 a sharp contrast in size between those of the interior and those of 

 the surface layer. An average stolon is four or five cells thick. 



The male branches, which are abundantly produced (Fig. 12, A, 

 B), are very short and arise directly from the main axis or one of 

 the axial branches. Some of the branches are simple and occupied 

 by a single inflorescence ; others become at once subdivided into 

 from two to six divaricate branches, most or all of which are 

 occupied by inflorescences. An individual inflorescence is mostly 

 0.4-0.6 mm. long and about 0.3 mm. wide. The narrow wing, 

 usually a single cell in width, spreads obliquely and is more or less 

 crenulate from projecting cells. The antheridia usually number 

 from six to eight and the openings into the antheridial chambers are 

 separated by one or two rows of cells, some of which bulge slightly. 

 No female plants have been seen by the writer. Stephani states 

 that the short female branches are papulose along the margin and 

 borne singly at the base of pinnae ; and that the "calyptra" is very 

 long, coarsely cellular-verrucose, and tipped by a small corona. 



The present species occupies a somewhat isolated position among 

 the Chilean representatives of Riccardia. It is about as large as 

 R. diversiflora and agrees with it in branching irregularly. Except 

 for these superficial resemblances, however, the two species have 

 but few features in common, and the diflferences between them are 

 striking. In R. florihunda, for example, the inflorescence is 

 dioicous, the edges of the thallus are rounded, the interior cells have 

 an average width of about 75 /x, and the branching seems to be 

 absolutely indefinite ; in R. diversiflora, on the contrary, the inflores- 

 cence is monoicous, the edges of the thallus are thin and sometimes 

 indistinctly winged, the interior cells have an average width of only 

 50 fx, and the branching in spite of its irregularity does conform 



