Sturch. — Harvey ella mirabilis ( Schmitz & Reinke). 85 
of the carpogonium or of the gonimoblast having been 
observed. 
In 1894 Dr. P. Kuckuck 1 published a description of the 
tetraspores of Choreocolax albus. He states that this plant 
is to be found in May, parasitic on Rhodomela subfusca , 
at Heligoland. From the figures of this plant it seems only 
to differ from Harveyella mirabilis in that the cells of the 
central mass of the parasite are not arranged in such obvious 
filaments as are the corresponding cells of II. mirabilis. 
But just at the time of the development of the tetraspores, 
the internal cells of H. mirabilis are occasionally so much 
gorged with contents, that the filamentous character of their 
arrangement is not very obvious, especially if the plane of 
section does not happen to coincide exactly with the long 
axis of the filaments of the parasite. I have frequently seen 
sections of H. mirabilis which corresponded exactly in 
appearance with the figures in Kuckuck’s paper. As the 
tetraspores are exactly similar to those of H. mirabilis , and 
the host-plant is the same, and the external appearance of 
the parasite described by Kuckuck resembles exactly that 
of H. mirabilis , while I have never seen any other parasite 
of similar appearance on Rhodomela subfusca , I am of the 
opinion that Choreocolax albus (Kuckuck) is simply a tetra- 
spore-bearing specimen of Harveyella mirabilis (Schmitz and 
Reinke). The tetraspores are stated to be sunk within 
the peripheral layer of the thallus, and to arise from wedge- 
shaped cells cut off from the growing peripheral cells. They 
are developed over the whole surface of the thallus, and are 
cruciately arranged. 
Nowhere in the literature dealing with the genus Harveyella 
have I found any account of the development of the cystocarp 
from the fertilization of the carpogonium to the production 
of the carpospores. The mature cystocarps of Harveyella 
mirabilis are found in Stokes Bay from December to March ; 
during this time the plant is common on the fronds of 
1 Choreocolax albus , von Dr. P. Kuckuck, Sitzungsberichte der Kon. Preuss. 
Akad. der Wiss., Berlin, 1894, xxxviii. 
