A Fountain Alga. 81 
dies. The life history of this fungus is at present under more 
detailed observation. 
In the general shape of the thallus, and the form of the chloro- 
plast as a parietal plate, this Alga bears a striking resemblance to 
the various species of Gongrosira J but unlike them, it is not in any 
way encrusted with carbonate of lime—on the contrary its natural 
substratum is a siliceous one. Also the zoospores are not formed 
in terminal and swollen zoosporangia in large numbers as in the 
Gongrosireae. Still on the whole it appears to agree more with the 
Gongrosireae than with any other group. 
1 Cliodat—“ Les Algues Suisses.” 
SUMMARY. 
1. A new fresh water Alga. 
2. Siliceous in habit. 
3. Grows in running water of low temperature. 
4. Forms an irregularly-branched star-shaped or circular 
thallus, the cells of which are longer than broad, containing a 
parietal chloroplast and no pyrenoids. 
5. By continuous division, beginning always at the centre of 
the thallus, the cells break up into zoosporangia, from which four 
zoospores issue. 
6 . The thallus may pass into a palmelloid condition, and in 
this condition the cells divide at once to form (a) zoospores, or (b) 
daughter cells which repeat the process. 
7. Bi-ciliate, pear-shaped zoospoores, with basin-shaped 
chloroplast, red eye-spot and colourless anterior portion. 
8 . Zoospores germinate without any period of rest into a new 
plant. 
9. No sexual stage known. 
The work on the above Alga was carried out in the Botanical 
Laboratory at Cambridge from July, 1902, to Christmas, 1903, and 
my sincere thanks are due to Professor H. Marshall Ward for per¬ 
mission to work in his laboratory and for his kind advice and 
encouragement. I have also to thank Mr. R. Wood, of Gonville 
and Caius College, Cambridge, for kind help with the drawings and 
diagrams, 
