- 136 



<fig. 10 and 12). Often root-fibres are emitted from the apices of 

 stunted or harmed ends of ramuli. Pericentral cells are 6 in ours and 

 throughly ecorticated. Articulations 6 times long as diameter in main 

 filaments (cells in that portion measure 2-3 mm. in length and 220- 

 250 /-/ in thickness), gradually becoming shorter above, in upper ramuli 

 becoming subequal to or shorter than the diameter. Tetra&pores 

 seriated in a longitudinal row in upper unaltere'd ramuli. Cystocarps 

 unknown. Colour darkish-brown in dried state. Substance soft and the 

 plant imperfectly adheres to paper in drying. 



Hab. : Myedoni Isl. in Komandorski Us. 



Setchell and Gardner remark that Pterosiphonia arctica has no hair, 

 but in ours it is provided though rather rudimentary. The presence of 

 hairs in Petrosiphonia, contrary to Falkenberg's statement, has already 

 been shown in Pterosiphoma-fibrillosa Okm. Icones Vol. II, p. 172-176, 

 PI XCVIII, 1912. 



PL. CLXXXV, Fig. 8-16. Fig. 8 : portion of frond of Pter. arctica 



(J. Ag.) Setch. and Gardn., \. Fig. 9 : upper portion of branch, 



1 1 ? -. Fig. 10: apical portion of branch; a, apical cell of branch; b, 



that of ramulus ; //, //, hairs, ^-p^. Fig. 11: root-fibre produced from 



stunted ramuli, -^-. Fig. 12: ramulus and dorsal hair, h, -p. Fig. 



13 : cross-section of branch, -4^-. Fig. 14 : articulation of primary 



filament, -?*-. Fig. 15: portion of branch bearing tetraspores, -^-. Fig. 



16: ramuli bearing tetraspores, -^-. 



