XXXIV] 



SPORANGIA 



^7 



is also an absence of any projecting receptacle. In these features the sorus 

 resembles that of Metaxya. The sporangia of the same sorus arise simul- 

 taneously in D. Lobbiana; but in D. coiijugata ^ 

 they are formed in succession, those which 

 appear later being distributed without order 

 amongst those first formed. The sorus, in fact, 

 compares with that of the Mixtac, but the 

 succession in time is not long maintained (Fig. 

 575). It thus appears that within the single 

 genus a direct transition is illustrated between 

 the "simple" and the "mixed" sorus. It is 

 a very natural transition, but its rarity within 

 such near affinity makes it notable. 



The sporangia present details of special 

 interest. Those oi D. Lobbiana are represented 

 from various aspects in Fig. 576, a-f. Seen 

 from the "peripheral" sidethe annulus appears 

 as a complete ring of cells, though the indur- 

 ation of those that are opposite the stalk is incomplete [a, b). A comparison 

 may be made with those of Glcichcuia liiieata (= G. dicJiotoma), which show 

 a b c 



g. 575. Dipteris conjugata. .•:/, young 

 sorus showing sporangia of different 

 ages in juxtaposition, (x too.) B, 

 younger sporangia. /, paraphyses. 

 (x 300.) (After Miss Armour.) 



!■ '&• 576- Sporangia of Dipteris Lobbiana seen from various points of view. ( x 50.) 



