122 Alexander W. Evans, 



projecting cells, giving a rough appearance to the upper surface 

 of the inflorescence. 



The female branches (Fig. i, A) are usually borne in a single 

 pair on the main axis of a photosynthetic branch-system. This 

 axis first gives rise to two vegetative branches, then to the two 

 female branches, and then to a considerable number of vegetative 

 branches. Occasionally there are deviations from this arrange- 

 ment. There may, for example, be more than two female 

 branches, or the female branch may represent the first secondary 

 branch of the system instead of the second. The female branches 

 are short and usually limited in growth after producing from one 

 to four archegonia; in very rare cases the branch may continue 

 its growth beyond the archegonia as a short and sterile extension. 

 The involucre, which may be understood to include the wings of 

 the female branch, consists of crowded and slender teeth or cilia, 

 sometimes eight or ten cells long. The large and massive 

 "calyptra" is, when mature, 3.5-4 mm. long and 0.9 mm. wide. 

 At its apex it bears a distinct corona, and its surface is otherwise 

 roughened by cells which are peeling ofif. Unfortunately no 

 sporophytes in good condition have been available for study. 



The close relationship which exists between R. prehensilis and 

 the New Zealand R. eriocaula (Hook.) Besch. & Massal. has been 

 brought out again and again. Schiffner (ig, p. 41) goes so far as 

 to imply that they may be synonymous and calls attention to the 

 fact that Leitgeb's account of R. eriocaula (15, p. 49) would apply 

 equally well to R. prehensilis.. As a matter of fact the two species 

 do resemble each other very strikingly. They have much the same 

 habit, they do not differ markedly in size, and they are both covered 

 over with surface-papillae. If their vegetative parts are carefully 

 compared, however, important distinctions at once become appar- 

 ent. Their surface-papillae, for example, are different in struc- 

 ture. In R. prehensilis, as we have seen, the papillae represent pro- 

 jections of the surface-cells, but in R. eriocaula they represent dis- 

 tinct cells, being cut off from the cells of the superficial layer by 

 walls. This difference is seen with especial clearness when the ulti- 

 mate branches of photosynthetic systems are compared. In R. pre- 

 hensilis the wings are three cells thick, being covered over by a 

 continuous layer of papillate cells ; in R. eriocaula, on the other 

 hand, the wings in the outer part are only one cell thick, and the 



