XXXVI I] 



LINDSAYA 



33 



Here as in Cibotium the receptacle arises from the actual margin of the 

 blade, into which the marginal segmentation is directly continuous (Fig.6o3,i), 

 the indusial flaps arising as superficial outgrowths. The upper {adax) is the 

 stronger from the first, and elongates into the false margin of the blade, 

 while the receptacle is tilted slightly towards the more delicate indusium 

 {abax). The first sporangia appear at the apex of the receptacle (Fig. 603, ii), 



Fig. 603, i — iii. Vertical sections through the. young sorus of Lindsaya linearis Sw. , in successive 

 stages of development. rt</(Z.r = the adaxial side, abax—\\\G. aljaxial side of each. The first sporangia 

 are marginal, and a gradate sequence is established at first, followed by a mixed condition. ( x 150.) 



and are thus marginal as they are in Thyrsopteris or Cibotiiuii. There is a 

 slight gradate sequence of the sporangia subsequently formed, especially 

 towards the lower indusium (Fig. 603, iii), but it merges later into a mixed 

 state, which becomes quite marked in later stages. The sorus being mixed, 

 the oblique annulus loses its mechanical importance. It would therefore seem 

 natural to find that the sporangia exhibit varying degrees of obliquity of 

 the annulus. The induration of the cells stops opposite the insertion of the 



Bin 3 



