i8o Alexander W. Evans, 



primary axis, if it gives rise directly to a photosynthetic system, 

 may taper toward the apex. The ultimate branches and the narrow 

 extremities of axes of higher rank are mostly 0.25-0.3 mm. wide. 

 Stolons are frequent and may arise directly from the main axis or 

 from the base of a primary, secondary or even tertiary branch. 

 They are in the form of slender and often irregularly branched, 

 terete or subterete structures, with a diameter of 0.1-0.2 mm. The 

 structure of the photosynthetic branches is much the same as that 

 of the axis, except that in the ultimate branches the central core 

 of thin-walled cells may be lacking (Fig. ii, E). In the stolons, 

 the sclerotic layer is very vaguely indicated, none of the cell- walls 

 being much thickened. 



The male branches are simple and often numerous. They arise 

 singly, rarely from the main axis, more frequently from a primary 

 branch, but usually from a secondary or tertiary branch (Fig. ii, 

 A). Occasionally a pinnate arrangement of the male branches is 

 distinguishable. The inflorescence (Fig. ii, F) occupies nearly 

 the whole length of the branch, and no cases of proliferation have 

 been observed. The inflorescence is mostly 0.5-1.5 mm, in length 

 and 0.35-0.45 mm. in length. The wings, which are one or two 

 cells wide, are spreading, erect or connivent, and the margin is 

 entire or vaguely crenulate from an occasional projecting cell. 

 The antheridia are mostly from four to twenty, and the openings 

 between the chambers are separated by from three to five cells, 

 numbers which are unusually high. 



The female branches (Fig. ii, B) are simple and very short. 

 They arise singly or in subopposite pairs, sometimes on the main 

 axis itself but usually on a primary or secondary branch. The 

 wing is deeply and irregularly lobed, the lobes being mostly three 

 to five cells long, acute to obtuse or rounded, and more or less 

 crenulate. The archegonia are very few but could not be counted 

 clearly in the specimens studied by the writer. The only "calyp- 

 tras" seen were immature. In this condition they are perfectly 

 smooth and are tipped by a distinct corona, shortly and bluntly 

 conical at the apex. 



In spite of its irregularity R. nudimitra resembles R. alcicornis 

 in several respects. The two species are of about the same size 

 and are both firm in texture ; they both show a tendency to become 

 very dark with age and to develop a purplish black pigmentation in 



