THE HOMOSPOROUS LEPTOSPORANGIATAi 



389 



show a certain likeness to Botrycliiujii. The sporanj:(ia arise 

 always in acroi)etal order from the apex of the terminal seg- 

 ments (sorophore) of the sporoph)'lI, and are strictly lateral in 

 origin, not originating from ei)idermal cells, bnt from marginal 

 ones. The young sporangium appears as a lateral outgrowth 

 of the margin, exactly like a young pinna upon the main axis, 

 and the young sorophore has the appearance of a young pinnate 

 leaf, and at this stage recalls strongly the similar one in Bo- 

 trychiiun. This is especially marked in Aiiciuiia and Lygo- 



FiG. 22y. — Cibotiiiin Menziesii. A, Pinnule with the sori (s), X3; B, a single sorus 

 showing the two-valved indusium, X9; C, a single sporangium, X80; r, the 

 annulus; D, a paraphysis, X8o. 



diiim, less so in Schizcea, where the sporangia are smaller, and 

 the mother cells project much more strongly. The early divi- 

 sions correspond closely with those of the Hymenophyllace?e, 

 and as there the tapetum is massive and two-layered, and the 

 stalk of the sporangium very short. The wall is derived in 



, The divisions in the wall are too complicated to be explained without 

 numerous figures. See Prantl's figures, Plate V.-VIII*. 



