68 3 
and the Flagellata. 
(recalling Gloeocystis ). They divide in all three directions and 
possess zoospores with unequal laterally inserted cilia. The 
conjugation of planogametes to form a zygote has been 
observed. 
Entodesmis (Borzi (’ 92 )) consists of elliptical, walled cells in 
tabulate mucilaginous colonies. The cells form zoospores 
with two unequal lateral cilia. These two genera have no 
Flagellate characters and are clearly of the status of the 
Tetrasporaceae. 
Phaeodactylon (Bohlin (’ 97 )) has a star-like cell with three 
arms in one plane and a central brown chromatophore. The 
cell-wall cannot be resolved into two pieces as with Diatoms. 
It floats freely in pools of brackish water and is considered to 
multiply only by vegetative cell-division. In Fig. 14, a and b 
represent aspects at right angles to each other. 
Stichogloea (Chodat (’9 7 a)) also multiplies only by vegeta¬ 
tive division, and thus with the previous genus represents the 
Pleurococcaceae-type. The cells are ellipsoid and grouped 
in fours to form a mucilaginous colony. 
Phaeothamnion (Lagerheim (’ 84 )) brings us to the filamentous 
brown Algae (corresponding with the green Confervoideae). 
It forms small tufts of slightly branched filaments growing 
attached in fresh water. Its discoverer, after some hesitation, 
placed it, in spite of its colour, in the green Confervoideae 
because he found its zoospores to have two equal apical cilia. 
This is accepted by Wille (’ 90 ) in Engler and Prantl, but 
Borzi (’ 92 ) asserts that the zoospores have two lateral unequal 
cilia. Our new knowledge of primitive brown forms shows us 
that this character is not an absolute criterion. On general 
grounds later authorities place it on the brown phylum. 
Phaeothamnion also forms * palmella ’ states. 
Pleurocladia (Klebahn (’ 95 ), Wille (’ 95 )) is a larger branched 
fresh-water brown Alga, and may be regarded as the simplest 
of those conforming to the long-recognized type with zoospores 
and gametes ; and here we may leave this ascending series of 
brown forms on well-established ground. 
While all the higher brown Algae are marine, it is perhaps 
