152 Alexander W. Evans, 



12. Riccardia fuscobrunnea (Steph.) comb. nov. 



Aneura fuscobrunnea Steph. Kungl. Svenska Vet.-Akad. Handl. 

 46'': 7. /. I, d. 191 1. 



Specimens examined: on banks of a brook, western end of. 

 Lago Fagnano, Tierra del Fnego, 1908, Halle (U., type of Aneura 

 fuscobrunnea) . Known only from the type locality. 



Although R. fuscobrunnea is so variable that it is difficult to 

 picture its distinctive features clearly, the species is evidently a 

 close relative of R. alcicor-nis. The original specimens are pale to 

 dark brown, becoming blackish in the older parts. The plants 

 grew in intricate tufts and the individual thalli look as if they had 

 been prostrate with ascending tips. Rhizoids are apparently 

 absent altogether. 



In well-developed plants (Fig. 5, F) the main axis is 0.3-0.4 mm. 

 wide, but it may be only 0.2 mm. wide in slender specimens. It 

 shows long-continued growth, the living portion being mostly 

 0.5-1 cm. in length. It is distinctly flattened, the thickness being 

 about 0.2 mm. and the cross section (Fig. 5, G) showing a biconvex 

 outline with rounded ends. The convexity is usually more pro- 

 nounced ventrally than dorsally but the difference is rarely very 

 marked. Measured in cells an ordinary axis is twelve to sixteen 

 cells wide and seven or eight cells thick in the median portion. The 

 cell-walls are slightly and uniformly thickened, but the walls of the 

 interior cells are somewhat thinner than the others. On the upper 

 surface the cells of the outside layer are about 40 /a long by 30 /x 

 wide; on the lower surface, about 40X22/X,. The interior cells 

 are mostly 70-100 ju. in length by 35 ;«, in diameter. When viewed 

 in cross section the contrast in size is therefore relatively slight, 

 especially when the interior cells are compared with those of the 

 upper surface. In Stephani's figure, which represents the cross 

 section of a branch, the contrast indicated is greater than in the 

 specimens themselves. 



The branching of the main axis is profuse, the branches being 

 given off at intervals of 0.3-0.7 mm. on each side (Fig. 5, F). 

 These branches spread obliquely and var}' greatly in appearance. 

 The most complicated are essentially like the main axis and show 

 indefinite growth with a bipinnate branching. Others are shorter, 

 soon limited in their growth and only once pinnate ; still others 



