Dar bishire. — On Actinococcus and Phyllophora. 265 
as Phyll. membranifolia (G. and W.) J. A g., the nemathecia 
of which are frequently met with, even in the Baltic. It 
is necessary that this point also should be elucidated. 
There are frequently found growing on specimens of PhylL 
Brodiaei in the Baltic, and more rarely in other seas, certain 
structures, which have been called ‘ Traubenkorper ’ (1, p. 9). 
Tetraspores, antheridia and procarpia are found on these, 
but they never apparently attain to maturity. Schmitz 
also mentions these peculiar bodies, referring them provision- 
ally as a new species to the genus Actinococcus Ktz. (5, 
p. 380). Kolderup Rosenvinge has described a new species 
of Ceratocolax , which apparently embraces the two organisms 
just mentioned, and to which he has given the name of 
Ceratocolax Hartzii K. Rosenv. (4, p. 34). 
The following is a brief description of the genus Actinococcus 
Ktz. and species Actinococcus subcutaneus . It is my intention 
to give a complete list of synonyms, literature and exsiccata 
in a later paper ; as also a discussion of the systematic 
position of this plant. 
Actinococcus Ktz. 
Literature', (i) Darbish., Beitrag, p. 7, &c. ; (2) Darbish,, Phyllophora-Arten, 
p. 36; (3) Gomont, p. 2, &c. ; (4) Kolderup Rosenvinge, p. 33; (5) Schmitz, 
Actinococcus, p. 392. 
Thallus parasitic on other Florideae, the vegetative portion 
consisting of filaments branching in the interior of the host- 
plant (intramatrical portion), and fertile filaments forming 
a cushion of parasitic tissue on the external surface of the 
host (extramatrical portion of the thallus). Antheridia and 
procarpia unknown. Tetraspores formed by cruciate division 
in radially disposed rows of tetrasporangia. 
Actinococcus subcutaneus (Lyngb.) K. Rosenv. 
Literature'. (1-4) The same as of the genus; (5) Schmitz, pp. 369-379. 
Synonymy : Actinococcus roseus Ktz. 
Thallus (asexual plant at least) parasitic on the young 
spermophores of Phyll . Brodiaei (Turn.) J. A g., which it 
