V] FERNS 93 



The fern spoken of by Dr Wallace as Dipteris 

 Horsfieldii (perhaps better known as DijJteris 

 conjugata (Fig. 12)), which grows with Matonia 

 jjecthiata on Mount Ophir and in the Malay region 

 generally, is one of seven species of a genus charac- 

 terised by a somewhat wider geographical range 

 than Matonia. Dipteris conjugata extends to the 

 Philippines, Samoa, Fiji, New Caledonia, New Guinea 

 and Central China ; its fronds, like those of Matonia, 

 are borne on long slender stalks attached to a 

 creeping stem ; they have a broad lamina divided by 

 a deep median sinus into two symmetrical halves and 

 each half is cut up into segments with a saw-like 

 edge. Several stout ribs spread through the lamina 

 from the apex of the long stalk like the open fingers 

 of a hand ; from these ribs smaller veins are given 

 off at a wide angle, and these in turn give rise to a 

 reticulum of finer veins forming a skeletal system 

 like that in the leaves of an oak and many other 

 flowering plants. 



Numerous groups of spore-capsules are borne on 

 the lower surface of the broad lobed frond. The 

 leaves of other species of Dipteris have the same 

 type of structure, but in some the segmentation of 

 the lamina is carried further and the leaf consists of 

 numerous long and narrow segments with one or two 

 main ribs. Dipteris is represented in the flora 

 of Assam, and it is interesting to find that a species 



