572 



ALEXANDER W. EVANS 



photosynthetic branch (Fig. 4, A). It is very short, the number of archegonia 

 being only two to four. The involucre (Fig. 4, G) consists of a series of irreg- 

 ular laciniae or cilia mostly three to five cells long and often coalescent at 

 the base. The calyptra, known only in a very young condition, is smooth or 

 nearly so, and the corona is inconspicuous. Unfortunately the sporophyte is 

 still unknown. 



In the preceding account A', leptostachya has been respeatedly compared 

 with R. variabilis, and several points of agreement have been pointed out. 

 The most important distinctions are perhaps the following: R. leptostachya is 

 on the whole a smaller plant; the photosynthetic branches do not broaden out 

 toward the apex to any extent and are more definitely winged, the wings being 

 distinctly crenulate; the male inflorescence is built up on a still more simple 

 plan, the openings into the antheridial chambers being uniformly separated by 

 single rows of cells; and the involucre of the female inflorescence is laciniate 

 or ciliate rather than crenulate. There is no known species of the Chilean 

 mainland with which R. leptostachya has much in common. In R. autoica, to 

 be sure, there is a somewhat similar differentiation into axis, stolons and photo- 

 synthetic branches, but this species is much more robust than R. leptostachya, 

 it shows almost no contrast in width between the external and internal cells of 

 the thallus, and the openings into the antheridial chambers are separated by 

 three or four rows of cells. 



Area of distribution: Endemic. 



'"13. R. nudimitra (Steph.) Evans, Trans. Connecticut Acad. 25: 177 f. 

 II (1921). — Syn. Aneura nudimitra Steph. Sp. Hepat. 6: 35 (1917). 

 On decayed wood. 



Masafiiera: ravine near the Campo Correspondencia, 1150 m. (no. 43). 



Since R. midiiiiitra has recently been described and figured by the writer 

 it will be sufficient here to compare it with R. leptostachya, the only Juan Fer- 

 nandez species that it resembles in any marked degree. In R. nudimitra the 

 differentiation of the thallus into branches or axes of various types is still better 

 marked than in R. leptostachya, although the creeping stem still retains its power 

 of curving away from the substratum and developing into a photosynthetic 

 system similar to those formed by the erect or ascending branches. The turf- 

 like appearance produced by the photosynthetic branches is very pronounced, 

 and the branches are far more rigid and opaque than those of R. leptostachya. 

 The rigidity is due partially to the smaller size of the cells, the surface-cells 

 averaging about 30 X 20 [x and the interior cells averaging only 25 [i in width. 

 The cell-walls, moreover, tend to be more strongly thickened, especially those 

 of the interior cells, and a vaguely defined strand of sclerenchymatous tissue 

 is sometimes discernible. This strand is more pronounced in the basal portions 

 of the photosynthetic branch-systems and in the prostrate axis, where it is in 

 the form of a compressed hollow cylinder with thin-walled cells inside. 



Area of distribution: South Chile; Masafuera. 



