TUr. TIIALLOSE HEPATICAE OF THE JUAN FERNANDEZ ISLANDS 563 



wide. Marginal cremilations, formed b\' [nojccting cells, are occasional!}' to be 

 observed, es[>ecially on the branchi udinients. Even here, however, they are 

 rarel)' conspicuous, and most of the l)ianches arc entire or nearly so. In some 

 cases branches or even rather complicated branch-systems assume the appearance 

 of stolons. Such branches, which are onK- 0.2 -O4 mm. wide, are slightl)- 

 flattened, but the edges are rounded and wholl\' destitute of wings. The devel- 

 opment of these stolon like structures, which are never highly differentiated, 

 seems to be induced when branches force their way under older thalli. 



The inflorescence of /v. adglutmata is normally autoicous although it is 

 difficult to demonstrate both antheridia and archegonia on every individual plant. 

 The male branches usually occur singly, more rarely in groups of two or three, 

 and arise directly from the main axis or from the base of a branch. The in- 

 florescence, which apparently never proliferates, occupies nearly the whole of 

 the branch and is sometimes recurved. It measures 0.3 — 0.7 mm. in length and 

 about 0.3 mm. in width. The marginal wings, although but one cell wide, are more 

 or less involute and distinctly crenulate; the antheridia number from four to 

 twelve; and the openings into the antheridial chambers are separated by two 

 rows of cells. 



The female branches are very short and are similar in position to the male 

 branches. Sometimes branches of both sexes occur in close proximity, although 

 there is nothing definite in their arrangement. The inflorescence occupies the 

 whole of the branch, and no instances of proliferation have been observed. 

 The involucre consists of a series of short cilia or narrow lobes, one to three 

 cells long and often more or less coalescent. The archegonia occur singly or 

 in small groups, six being the highest number seen. The massive »calyptra» 

 measures 2.4 mm. in length and about 0.9 mm. in diameter at maturity and is 

 then almost smooth. In younger stages the surface is covered over with rounded 

 cells or groups of cells, and the ape.x bears a low but distinct corona. 



The material examined includes a few mature sporophytes in excellent 

 condition for study. The oval capsule is about i 2 mm. long and 0.45 mm. 

 wide, and the wall shows the usual two layers of cells. In the outer laj^er the 

 cell-walls turned toward the median lines of the valves show numerous bands 

 of thickening, which extend partially or wholly across the inner tangential walls 

 and thus form incomplete rings; in the iniier la\-er the cell-walls are thin 

 throughout. The spores are greenish and 18 — 22 u. in diameter, while the slightly 

 thickened walls are covered over with minute verruculae. The eleaters, which 

 are brown and long-pointed at each end, are mostly 0.15 — O 3 mm. long by 

 10 — 12 a wide and show a single, broad, loosely wound spiral. 



Gemmae are sometimes produced in considerable abundance on rather 

 narrow vegetative branches. They conform to the characteristic two celled type 

 and average about 50 X 30 a, their walls being slightly thickened. 



When R. adgluthiata is typically developed its dark and opaque thallus. 

 often tinged with yellowish or reddish, is very different in appearance from the 

 more or less translucent thallus of R. byeviramosa. Unfortunately, in poorh' 

 developed material, the opacity is sometimes less pronounced, and the plants 

 then bear a certain superficial resemblance to the older species. In their cell- 

 structure, moreover, R. adglutinata and R. breviraniosa are a good deal alike; 



