Thomas. — Notes on Cephaleuros. 783 
process was seen by him. Sporangia borne on special aerial branches 
are also described, corresponding with those of My coidea parasitica. The 
Alga of this monograph was always extra-cuticular, except on Citrus leaves, 
in which case Marshall Ward failed to determine the origin of the sub- 
cuticular position. 
Mobius (11), under the name Phyllactidium tropicum , describes and 
figures an Alga which closely corresponds to one of the Ceylon forms of 
this investigation ; it is epiphytic and extra-cuticular, and grows by means of 
false dichotomy, which, owing to the fact that the walls are not formed 
simultaneously, Mobius describes as monopodial branching. Very charac- 
teristic of this form are the pores which he describes in the transverse walls. 
Hariot (5), in a paper on Cephaleuros , points out that the description of 
Cunningham’s Mycoidea parasitica corresponds with that of Kunze’s genus 
Cephaleiiros founded fifty years previously ; these are forms in which 
the plant is firmly fixed to the host by rhizoids. Hariot includes in the 
genus Phycopeltis all the easily detached forms such as Phyllactidium 
tropicum (Mobius). 
Karsten (6), in a summary of this family, takes a more comprehensive 
view than Hariot ; he substitutes Cephaleuros for all the many-layered disc 
forms, and includes in Phycopeltis all the regularly shaped one-layered discs. 
To the Alga described by Cunningham and Marshall Ward, he gives the 
name Cephaleuros mycoidea. 
The most recent contribution to the study of these forms is that 
of Vaughan Jennings (14) who investigated two species of Phycopeltis from 
New Zealand. Under Phycopeltis expans a, he describes a form which 
in the young stages closely resembles the a Ceylon plant, and his form 
seems to be associated with Fungal hyphae and Lichen-forming hyphae. 
The Fungal hyphae are colourless in their young, and brown in their older 
stages, and they are apparently independent of the Alga. They grow, 
however, between the Alga and the leaf surface and follow the course 
of the radial walls, occasionally anastomosing by sending branches along the 
transverse walls. Although the figures of Vaughan Jennings are not very 
clear, the association of Alga and Fungus, which does not affect the Algal 
growth, is interesting. 
Certain interesting features, hitherto undescribed, were observed in 
an epiphytic Alga from Ceylon, collected by Professor Farmer. Supple- 
mentary material, sent from Barbadoes by Mr. W. Nowell, has been 
examined in conjunction with the Ceylon organisms. 
On the leaves collected in Ceylon, two distinct forms were found, both 
occurring on the upper surface of the leaf, from which they are easily 
detached. For the present these are designated a and /3 forms. The discs 
of the a organism are, for the most part, circular, but assume a more 
or less lobed appearance in the maturer plants examined ; the cells are 
