1028 JOTTINGS PROM BIOLOGICAL LABORATORY, SYDNEY UNIVERSITY, 



the leaf-bearing parts of the stem there is to be seen another 

 tissue between the epidermis and the cortical layer, not forming 

 a complete zone but arranged in tine masses ; this is the mesophyll 

 of the leaf-ridges, and does not differ from that of the leaves. 



The leaves seem not to follow any definite law in their arrange- 

 ment. In every 2| centimetres of the stem there are about five 

 leaves, and of these the fifth is very usually directly over the first. 

 About two centimetres below each leaf begins a lonijitudinal ridse 

 of the stem, which, at first very low, becomes very prominent 

 towards the base of the leaf. The leaves are situated with one 

 edge directed inwards towards the stem, the midrib of the leaf 

 meeting the stem at an angle of about 45°. The leaves are of a 

 long oval shape, on an average a centimetre and a half in length 

 and half a centimetre in breadth, having the base asymmetrically 

 developed, the inner half of the lamina— that turned towards the 

 stem — being more developed than the outer. The inner edge some- 

 times presents a few indistinct serrations, but in this there is much 

 variation. There is a single unbranched midrib, which is produced 

 at the extremity into a spine-like point. 



The epidermal cells of the leaf have a lobed outline; their outer 

 wall forms an irregularly thickened cuticle like that of the 

 epidermis of the stem. Stomata may sometimes be found in equal 

 abundance on both suifaces of the leaf, but in some cases they 

 may be more abundant on one side than on the other, or they may 

 be entirely absent on one side though abundant on the other. The 

 mesophyll of the leaf and of the leaf-indges consists of elongated 

 cells which present at tolerably regular intervals short, blunt pro- 

 jections articulating with corresponding processes from neighbour- 

 ing cells — a form of tissue resembling that found in the leaves of 

 some species of Lycojjodium., though in the latter the tissue is looser 

 and the cell-processes more elongated. 



Each sporangium (' sorus ' in Bentham and Mueller's description) 

 is borne on a special short side-branch which terminates in a sym- 

 metrical pair of leaves (' bracts ') similar to the ordinary leaves, 

 but smaller ; the whole obviously representing the fertile cone-like 



