Ophioglossum pendulum (£.), &c. 407 



Beserve,* near to Hanwella, in Ceylon. On the humus contained in 

 this being carefully examined prothalli of various ages were found. 

 They were distributed throughout the humus, the majority being found 

 near the bottom of this, often embedded among the ramenta which 

 clothe the rhizome. 



The very young prothalli are button-shaped, the slightly conical 

 lower part expanding above. The basal region is brownish, the surface 

 of the upper portion a uniform dull white. The latter tint is due to 

 the close covering of paraphyses, which, at this age, extends unin- 

 terruptedly from just above the base over the whole surface of the 

 prothallus. The youngest prothalli are thus clearly radially sym- 

 metrical. In slightly older prothalli, seen, from above, the circular 

 outline is lost, owing to the more active growth of two or three points 

 on the margin. This continues, and there thus arise a corresponding 

 number of cylindrical branches, the prothallus becoming irregularly 

 star-shaped. At first the branches spread out in a horizontal plane, 

 though with a slight upward tendency. But when the branches them- 

 selves subdivide all suggestion of this' secondary clorsiventrality is lost, 

 and the larger prothalli consist of branches radiating in all directions 

 into the humus (fig. 1). 



From a short distance behind the smooth, bluntly conical apex the 

 surface of the branch is covered with short, wide, unicellular paraphyses 

 analogous to those known in prothalli of Lycopodium Phlegmaria. These 

 are only absent above the sexual organs. 



The prothalli are monoecious, antheridia and archegonia being found 

 close together on the same branch. The surface projects very slightly 

 above the large sunken antheridium • the neck of the archegonium, 

 which, as seen from above, is composed of four rows of cells, hardly 

 projects from the prothallus. The sexual organs thus resemble those 

 of 0. pedimculosum, as described by Mettenius. 



Ehizoids have not been seen on any of the numerous prothalli ex- 

 amined. An endophytic fungus occupies a middle zone of tissue in all 

 the branches, the superficial layers and a central core of cells being 

 free from it. 



Helminthostachys zeylanica. 



The prothalli of this plant were also found in the Barrawa Forest 

 Eeserve, a low-lying jungle subject to frequent floods. Young plants 

 still attached to the prothallus were fairly abundant in certain spots, 

 and, by searching in the rotting leaf mould around, prothalli of various 

 ages were obtained. The prothalli were found at a depth of about 

 2 inches. 



* I am indebted to my friend Mr. F. Lewis, who guided me to this locality, for 

 the assistance he aSbrded me in my search for the prothallus of Ophioglossum and 

 Helminthostachys. 



VOL. LXVIII. 2 F 



