The Genus Riccardia in Chile. 149 



out by the measurements, the surface-cells averaging about 27 x 

 12 /t and the interior cells measuring ^o-yo fihy about 17 ju,. The 

 cross section of the axis shows a width of sixteen to eighteen cells 

 and a thickness of eight to twelve cells. Most of the walls are thin, 

 but the second and third layers of cells from the outside sometimes 

 show slightly and uniformly thickened walls. No pigmentation 

 of the walls has been observed. 



At intervals of 0.5-1.5 mm. the axis gives off obliquely spreading 

 branches (Fig. 5, A-C). An occasional branch shows long- 

 continued growth and repeats the features of the axis. Most of 

 the branches, however, are shorter and limited in growth, in spite 

 of their blunt apices, attaining a length of perhaps 1.5-2 mm. and 

 usually measuring 0.3-0.4 mm. in width. Each of these shorter 

 branches usually bears two or three secondary branches on each 

 side, a gradual decrease in length being often apparent in passing 

 from base to apex. The secondary branches are mostly simple, 

 but the longer branches toward the base sometimes give off from 

 one to three short tertiary branches. The secondary branches are 

 about 0.2 mm. wide and the tertiary 0.12-0. 15 mm. The branches 

 of whatever rank are similar in structure and are apparently never 

 differentiated as stolons. There is, however, a tendency for the 

 surface-cells on the branches to be wider than on the axis (Fig. 5, 

 E), attaining a width of perhaps 16 /x, so that the contrast in size in 

 section view is even less marked. Some of the branches, more- 

 over, thin out toward the edges, appearing subacute in section, and 

 an interrupted row of marginal cells can sometimes be distin- 

 guished. 



The male branches arise directly from the main axis (or from 

 one of the large axial branches). The inflorescence, which is 

 usually 0.3-0.4 mm. long and 0.2-0.25 mm. wide, occupies nearly 

 the whole of the branch and very rarely proliferates. The spread- 

 ing wings are one or two cells wide and entire or nearly so, the 

 marginal cells projecting very slightly or not at all. The features 

 of the antheridial chambers are not clearly shown in the material 

 at hand, but the antheridia usually number from four to eight. 

 The archegonia, so far as observed, never exceed four, and the 

 branches show no signs of proliferation. The involucre consists 

 of a wing which is mostly four to six cells wide and variously 

 lobed or lacerate, the lobes being either blunt or sharp. Some- 

 times the wing is supplemented by a few similar outgrowths 



