258 The Royal Society, London. 



which is formet! of four rows of cells, projects distinctly from the 

 prothailus. 



The distinetion made above between a Vegetation and a repro- 

 ductive region in this prothailus is supported by the distribution of the 

 endophytic fungus. This is entirely absent from the reproductive region, 

 but in the basal part occupies a wide zone between the two or three 

 superficial layers of cells and the central tissue, which are free from 

 the fungus. 



The young plants attain a considerable size while still attached to 

 the prothailus. Plants with three leaves and as many roots have 

 been seen, the prothailus of which showed no sign of decay. The first 

 leaf is ternate and has a leaf-stalk of variable length. The lamina is 

 green and reaches the light. A Single root corresponds to each of the 

 early leaves. 



Examination of the prothalli connected with young plants indicates 

 the position they occupied in the soil. Most commonly the long axis 

 of the prothailus was vertical", sometimes, however, it was oblique, and 

 occasionally horizontal. 



Psilotum sp. 



The prothailus of this plant was looked for withont success in 

 Ceylon, both in the mountain region and on the roots at the base of 

 C o c o & palms near the coast. In the localities visited on the west coast 

 of the Malay Peninsula Psilotum was not abundant. On Maxwell's 

 Hill, in Perak, I found it scantily on ßtems of tree-ferns, the rhizome 

 growing among the roots of the fern, which cover the stem. No young 

 plants were found; but a single prothailus, embedded among the roots of 

 the fern in close proximity to a plant of Psilotum, was obtained. 

 This prothailus, as will be evident from and the description below, could 

 only belong to Psilotum or be that of some species of Ly c o po dium, 

 the gametophyte of which has not been described. From the position in 

 which it was found, the former supposition is the more probable one, 

 but such evidence of association is of course not conclusive, and the 

 specimen can only bedesciibed as the prothailus of Psilotum with the 

 reservation expressed above. 



The prothailus when frosh measured about one-quarter of an inch in 

 length by about three -sixteenths of an inch at the widest part, which, 

 as shows, is above. The lower portion is cylindrial and rounded below. 

 To one side near the lower end is a well-marked conical projection 

 directed obliquely downwards, which clearly corresponds to the primary 

 tubercle of the prothailus of Lycopodium cernuum. The surface 

 of the lower three-fourths of the prothailus was brown and bore rhizoids. 

 The latter were absent from the upper part, which widens out suddenly, 

 the increase in width being due to the projection of the thick, coarsely 

 lobed margin of the summit of the prothailus. The central region of 

 the summit is smooth and somewhat depressed. The upper portion of 

 the prothailus had a faint green tint when fresh, but no Chlorophyll 

 grains could be detected. 



In the tissue of the overhanging margin the numerous sunken 

 antheridia occur, closely crowded together. Archegonia have not been 

 observed on external examination. 



