TJie Genus Riccardia in Chile. 155 



face layer are mostly 20-30 /x long and 12-20 /a wide, while the 

 interior cells are 70-120 /a long and about 25 /x in diameter. 



The superficial cells of the axis and also of the branches are con- 

 vex, and every cell (or nearly every cell) bears an outgrowth or 

 appendage of some sort. In their simplest expression these out- 

 growths are single, bluntly pointed, superimposed cells, with the 

 wall more or less thickened at the tip. If often happens, however, 

 that the outgrowths of two or more adjoining cells are coalescent 

 and thus give rise to more complicated appendages, the most com- 

 plex of which are in the form of spinulose leaf-like lobes, four or 

 five cells wide at the base and two to four cells long. In such an 

 appendage nearly every cell is bluntly pointed with the wall thick- 

 ened at the tip, and the cells which are not marginal often project 

 at various angles. Between the simplest and the most complicated 

 outgrowths are all possible gradations. The adjoining cells with 

 coalescent outgrowths are usually in longitudinal rows but may be 

 in slightly divergent rows. The outgrowths thus show a tendency 

 to be longitudinal in position, but there is otherwise little regularity 

 in their arrangement, and the whole surface of the thallus is so 

 closely covered by its appendages that the outlines of the superficial 

 cells are difficult to distinguish. 



At intervals of 0.5-1.5 mm. on each side the axis gives ofif 

 obliquely to widely spreading branches. Except in those rather 

 rare cases where the branch represents a new axis, the branches are 

 quickly limited in their growth, measuring usually 1-4 mm. in 

 length and 0.15-0.2 mm. in width. They are either simple or bear 

 from one to five secondary branches, which are shorter but scarcely 

 narrower than the primary branches. Occasionally a very short 

 tertiary branch is produced. The structure of the branches is 

 essentially like that of the axis. 



Both male and female branches are borne on the same thallus, 

 the species being autoicous. The male branches are not abundant 

 and always arise on primary branches in the material studied. The 

 terminal inflorescence, which apparently never proliferates, some- 

 times occupies nearly the entire branch but is sometimes approached 

 or even surpassed in length by the basal sterile portion of the 

 branch. It measures 0.25-0.45 mm. in length and about 0.2 mm. 

 in width, and the antheridia usually number five to eight. The 

 whole surface of the inflorescence is covered with appendages; 



