A. J. W. Hornby. 
41 
A NEW BRITISH FRESH WATER ALGA. 
By A. J. W. Hornby, B.Sc. 
[With Four Figures in the Text.] 
T HIS species of Endoderma was discovered in 1914 epiphytic 
on Cladophora glomerata which was attached to the sides 
of Rowton’s Well in Sutton Park, Warwickshire. This well is 
very little used, and the water is very fresh and pure. 
Besides being endophytic and epiphytic on Cladophora it was 
also observed on Rhizoclonium hieroglyphicum , but only rarely, and 
nothing like to the same extent did it penetrate the walls of the 
latter compared with the former Alga. Chcetomorpha sutoria though 
present was unaffected. 
The Endoderma is at first epiphytic on the host in the same 
manner as Aphanochcete, and then it is observed to penetrate the 
thick laminated cellulose walls of the host. The result is a thallus 
of Endoderma , two or three cells thick, round the branched fila¬ 
ments of the Cladophora. It is evident that the thallus is produced 
by the anastomosing of the branches of the Endoderma, closely 
knit together by successive laminae of the host-wall. 
The cells are at first rounded, but soon become angular by 
the anastomosing of the branches in all directions. They are 
uninucleate and differ very much in size. The diameter varies 
from 3-5 to 17‘5/x; the average diameter is 12/t. The cell-wall is 
thick and quite destitute of hairs. There is one irregular parietal 
chloroplast, containing one, rarely more, pyrenoids, and some 
starch-grains. It is very dark green in colour, and apparently 
there is no evidence of parasitism in this plant, the Cladophora 
being unaffected to any observable extent. 
Including the present species the genus Endoderma now 
contains ten species. It is proposed to call the alga under con¬ 
sideration E. Cladophorce. Huber 1 in discussing certain members 
of the Chcetophoracece divides his genus into two sections, those 
without bristles and with one pyrenoid in each cell, which he groups 
in the section “ Entocladia,” and those with bristles and several 
pyrenoids, which he groups in the section “ Ectochcete." 
The former were mostly marine, but since then three species 
have been discovered, which are all freshwater, and occupy a 
place in 11 Entocladia.'" They are the West Indian E. Pithopliorce 
J. Huber, Contrib. a la conn? d. Chaetophorees (Ann., Sc. Nat. 7). 
Ser. Botan. T. 16. Paris, 1892. 
