222 DIPTEROID FERNS [CH. 



of the latter state have, however, been seen in Dipteris coiipigata (Vol. 11, 

 p. 317). In Cheiropleuria and in Christopteris, on the other hand, the soral 

 area is greatly extended, with a "mixed" character fully developed. But 

 while Cheiropleuria is singularly archaic in its anatomy, as well as in its 

 sporangial structure and spore-output, the sporangia of CJwistopteris and of 

 Platyceriinii correspond in structure and in spore-output to those of Neo- 

 cJieiropteris, all having adopted the ordinary Leptosporangiate type. They 

 also all agree in the absence of a perispore. 



One of the most distinctive features in these Ferns is the elaboration of the 

 receptacular vascular tract, which seems to be a peculiarity of the Matonioid- 

 Dipteroid Ferns. In Matonia sarmentosa the sorus is terminal on a vein 

 (Vol. II, Fig. 497, a): but in M . pectinata it is seated on a stellate fusion of 

 strands {b). In Dipteris Lobbiana though the sorus is a large one there is no 

 special vascular supply (Vol. II, Fig. 571). The condition seen in Cheiropleuria, 

 Platyceritmi and Christopteris results clearly from soral extension from the 

 Dipteroid type, and it is accompanied by extensions of the vascular tissue 

 of the receptacle, resulting in the diplodesmic state seen in their sporophylls. 

 It seems probable that the soral supply in Neocheiropteris may have arisen 

 similarly, but from a Matonioid source, with extension of the vein-junction 

 to form the vascular ring. Whether this be so or not, it will be found to 

 provide an interesting point for comparison with certain Polypodioid Ferns. 



Hymenolepis SPICATA (L. fil.) Presl 



Few Ferns have suffered under so varied a synonymy as this species. It 

 has lately been examined in detail by Von Goebel {Anti, Jard. Bot. Biiit. 

 XXXVI (1926), p. 108), with results which appear to fix its natural position 

 more clearly than before : so that the history of its systematic changes need 

 not be followed in detail here. It may suffice to say that it will now take 

 its place as a specialised Dipteroid-derivative on the one hand ; while, as 

 Von Goebel concludes, it has much in common with the Pol}'podioid Ferns 

 comprised under Pleopeltis. 



This plant is one of the commonest epiphytes in the Malayan region. It 

 was described by Linnaeus as Acrostic/mm spicatum, and was well figured by 

 Hooker under Presl's name of Hymenolepis spicata {Exotic Ferfis, PL LXXVii). 

 From its creeping rhizome spring in two rows the narrow, unbranched, 

 lanceolate and leathery leaves, with marked mid-rib, and venatio anaxeti. 

 When fertile the leaf is contracted at its distal end, and its margins reflexed 

 to cover the two broad linear coenosori (Fig. 731, 34, 36, 3.SJ. From the 

 thickened receptacle arise the numerous sporangia, associated with long- 

 stalked peltate scales (40, 41). The rhizome is described by von Goebel as 

 containing an attenuated vascular system, associated as in so many Dip- 

 teroid Ferns with dark masses of sclerenchyma. The venation of the sterile 



