562 ALEXANDER W. EVANS 



in groups of two or tliree, the wing crenulate, one cell wide, usually somewhat 

 involute; antheridia usually four to twelve: $ inflorescence occupying a simple 

 and very short branch; involucre composed of short cilia or lobes, one to three 

 cells long and often more or less coalescent; archegonia borne single or in small 

 grou[)s; calyptra while young covered over wiih rounded cells or groups of 

 cells and showing a low but distinct corona, afterwards becoming nearly smooth: 

 cells of outer layer of capsule wall with numerous thickenings in the form of 

 incomplete rings; cells of inner !a}'er without local thickenings; spores greenish, 

 minutely verruculose. 



On rocks and decayed logs, 600 m. and below. 



Masatierra: V. Anson, near Plazoleta, on decayed timber, 260 m. (no. 27); 

 El Yunque, in moist woods, SkottSBERG 1908 (mixed with R. breviyantosa, 

 (no. 28 a); V. Colonial, Q. Gutierrez, c. 300 m. (no. 29); B. Cumberland, on 

 moist cliffs near the sea (no. 30); SW. slope of Co. Piramide, c. 600 m. (no. 31); 

 Q. Juanango, in forest, c. 250 m. (no. 32, 33); Q. Juanango, waterfall (no. 34). 



Masafuera: innermost accessible part of Q. de las Casas, on trunks, c. 

 200 m. (no. 35); O. de las Casas, on log in the stream (no. 36). No. 35 may 

 be designated the type. 



The present species (Fig. 2, A, B) grows in depressed mats and is usually 

 opaque. It is dark green in color but often shows a peculier yellowish or 

 reddish brown pigmentation even in the younger portions. The axis and most 

 of the branches cling closely to the substratum by means of crowded rhizoids, 

 making it difficult to remove intact thalli. The axis is strongly flattened (fig. 2, 

 C), measuring 2 — 4 inm. in width and only 0.3 — 0.35 mm. in thickness, while 

 the length of the living portion is usually 1—2 cm. The upper surface is plane 

 or nearly so, and the lower surface is somewhat convex. From the median 

 portion, which is usually six to eight cells thick, the axis thins out gradually 

 toward the margins; here an indistinct wing, one or two cells wide, is some- 

 times distinguishable, but the axis is often wingless and shows no signs of a 

 differentiated row of marginal cells. The surface-cells average about 45 X 30 [x, 

 but the innermost cells measure 100 — 140 [x in length by about 80 [j. in width. 

 In cross section there is therefore a gradual increase in width in passing from 

 the surface inward. The cells walls are thin throughout. 



Branches are given off by the axis at indefinite intervals (Fig. 2, A, B) 

 and the thallus scarcely ever approaches a regularly pinnate condition. The 

 primary branches are sometimes so close together that they overlap, but they 

 may be separated by a distance of i mm. or more. In some cases they equal 

 the axis in width; they tend, however, to be narrower and are sometimes only 

 05 mm. wide. Except in unusual instances, where the primary branches rep- 

 resent new thalli, they rarely exceed a length of 5 mm. In most cases sec- 

 ondary and even tertiary branches are present, but these usually remain very 

 short and may not develop beyond a rudimentary condition. Under such 

 circumstances the higher axis shows one or more very short bilobed outgrowths, 

 with rounded lobes and apical cells in the depressions between them. The 

 branches are nearly as thick as the main axis but tend to thin out more 

 abruptly and are sometimes bounded by fairly distinct wings two or three cells 



