MARATTIACEAE 



513 



view of its origin, since its sporangial structure is closely similar to that 

 of Angiopteris, while such elongated sori are absent from the corresponding 

 fossil types. A similar elongation of a synangial sorus of the Marattia- 

 type, so as to extend the full length of the vein, would give the condition 

 seen in Danaea (Fig. 283 j, K, or better in Fig. 286 A) ; here also the 

 sporangia are disposed as in Marattia, but differing in the minor fact 



,t- 



G +5 



K 



FIG. 283. 



Sori and sporangia. A, B Angiopteris crassipes, Wall, A= sorus. .5 = two 

 sporangia, one in surface view from without, the other cut longitudinally. C, D = Arch- 

 angioptcris Henryi, Christ et Giesen. C = sorus. D = two sporangia in section. /?, f= 

 Marattia fraxinea, Sm. E synangium ; ^"^thesame in section. G, H = Kaulfussia 

 aesculifolia, Bl. G part of 'the lamina seen from below, with three synangia ; the 

 numerous small circles on the leaf-surface are stomata. // = section through a synangium. 

 y, K= Danaea elliptica, Sm. y = two synangia; K= section through a synangium. 

 (A, B, E, G, J after Bitter. C, D after Christ and Giesenhagen. F, H, K after 

 Hooker-Baker. From Engler and Prantl, Nat. PJJanzenfam.'). 



that the valley between the rows of them is almost levelled up, and the 

 sorus thus forms a solid cake. It will be shown shortly that developmental 

 details support the view that such elongation has actually taken place, 

 while the fact is worthy of note that the length of the sorus varies greatly 

 in different species of Danaea. And lastly, in Kaulfussia the synangial 

 association of the sporangia together in the circular sorus is on the plan of 

 Marattia and Danaea (Fig. 283 G, H). The origin of the numerous sori 

 by fission from the Da/mea-type as the lamina expanded has already been 



2 K 



