670 MISS RATITBONE ON MYRIACTIS ARESCHOUGIL 
Notes on Myriactis Areschougii and Coilodesme californica. 
By May Ratusoye. (Communicated by V. IT. Buackman, 
M.A., F.1S.) 
[Read 3rd December, 1903. ] 
(Puiate 24.) 
Ir is hoped that the following observations on Myrvactis 
Areschougii and Coilodesme californica, fragmentary as they 
are, may be of some use in helping to bridge over one or two 
of the numerous gaps in our knowledge of the life-history and 
structure of the parasitic and symbiotic marine alge. 
Myriactis Arescnoveatt, Batt., is synonymous with Hlachistea 
Areschougii, Crouan, as in 1892 Mr. Batters transferred to Myri- 
actis the latter species, together with EZ. stellulata, on the ground 
of the absence of paraphyses and the entire or partial immersion 
of the basal portion of the parasite in the thallus of the host. 
If this view be accepted, one of the generic characters given by 
Kjellman, viz., the tapering at both ends of the assimilating 
filaments, will require modification, as in M. Areschougii the 
assimilating filaments are distinctly broadened and thickened at 
the upper ends. Kiitzing’s original diagnosis of the genus, 
however, presents no such difficulty. 
M. Areschougii was first discovered by the brothers Crouan in 
September 1860, growing on Himanthalia lorea at the entrance 
to the Port of Brest, and published by them, under the name of 
Elachistea Areschougii, in their ‘ Liste des Algues Marines,’ and 
they figure and describe it in the ‘ Florule du Finistére.’ 
Of the two figures given, one shows the plants on Himanthalia 
lorea in their natural size; the other is a magnified section of 
part of a tuft, but unfortunately the drawing of this last is not 
very good, especially where it shows the immersed portion of the 
thallus. 
In March and May 1877 M. Bornet found this alga again at 
Le Croisic, and it is to this he alludes when he states in the 
‘Etudes Phycologiques, p. 21, that he has found Elachistea 
clandestina upon Himanthalia lorea. This confusion between 
the species, of which he, himself, informed M. Sauvageau, arose 
from the fact that the Crouan specimen named E. Areschougii 
in his herbarium really belonged to another species. 
M. Sauvageau, in a very interesting paper in the ‘ Journal de 
