THE THALLOSF, HEPATICAK OF THE JAUN FERNANDEZ ISLANDS 559 



Area of distribution: Soutli Chile, Magellan region to Fuegia and neigh- 

 boring islands; Masakiera. 



8. R. brcvirain()sa (Stcph.) Evans, comb. nov. — Syn. Aiieura brcvi- 

 ramosa Sieph. Kungl. Svenska Vet.-Akad. llandl. 46'-': 6 f. I a(i9ii). — Fig. i. 

 On tree ferns, decayed logs and rocks, 700 ni. and below. 



Masaticrra: 1^1 Yunque, in moist woods, SkoT'ISHEKG 1908 (no. i, cited 

 by Stephani, 6); B. Cumberland, caves V and VI, mostly on the side and 

 back walls (no. 21, 22, 23, 24) and in the old caves near landing (no 24 a); 

 SVV. slope of the Portezuelo ridge, ravine among Dicksonia, 550 m. (no. 25); 

 C. Salsipuedes, Dicksonia forest, 660 m. (no. 26); without exact locality, Reed 

 (Herb. Mitten, cited under Riccaniiiis niiiltifidns by Mi'iTEN, 88). 



*Masafuera: E. of Las Inocentes, on Dicksonia, 700 m. (no. 27). 



This is apparently the most abundant species of Riccardia in Juan Fer- 

 nandez. It was based on two specimens from Masatierra and one from the 

 vicinity of Port Stanley, Falkland Islands. One of the Masatierra specimens 

 came from the vicinity of the colony and the other from El Yunque. The 

 latter has been examined by the writer and includes specimens of the following 

 species as well as the true Aneura breviraniosa. SlEPHANl's figure represents 

 the cross section of a primary branch and is exceedingly diagrammatic. 



The thalli of R. breviramosa (Fig. i, A — C) are prostrate and grow in 

 depressed mats, sometimes in layers. They present a translucent appearance, 

 and the color varies from dull green to brownish. Rhizoids are scantily pro- 

 duced and are largely restricted to the stolons, so that the plants are only 

 loosely attached to the substratum. 



The main axis is mostly i — 2 mm. wide and 0.3 — O 33 mm. thick, and the 

 living portion is 1-2 cm. long. The upper surface is plane or nearly so 

 (Fig. I, D), the lower surface is distinctly convex, and there is a gradual thinning 

 out toward the margins, which are bounded by more or less crenulate wings 

 one to three cells broad. In the median portion the axis is mostly eight to 

 ten cells thick. The cells of the surface layer are scarcely longer than broad, 

 averaging about 55 jj. in length by 45 jj, in width; along the margin they are 

 distinctly smaller, measuring perhaps 32 [j. in length. The interior cells are 

 about 80 [X wide and 160—200 [j. long, so that there is a rather marked contrast 

 in width when the surface-cells and the interior cells are compared. Except 

 in size the cells show little differentiation, and the cell-walls are everywhere 

 thin or only slightly thickened. 



The primary branches are rarely more than i mm apart and are some- 

 times so close together that their bases are almost in contact. They spread 

 obliquely to widely and sometimes give the thallus a regularly pinnate appear- 

 ance. In rare cases a primary branch represents a new axis and continues its 

 growth indefinitely. Usually it stops growing after attaining a length of 4—6 

 mm. and under such circumstances is both narrower and thinner than the axis, 

 measuring perhaps 0.7— o 9 mm. in width and 0.2 mm. in thickness. At inter- 

 vals of about 0.5 mm. on each side the primary branches give rise to short 

 secondary branches, which are rarely more than 0.5 mm. in length, 0.3 mm. in 



