Butler.—On Allomyces , a new Aquatic Fungus . 1031 
nected by many essential characters, through Allomyces , with the typical 
Leptomitaceae. 
Of this series Monoblepharis must be taken, I think, to preserve the 
most primitive characters in its peculiar sexual processes. Of recent years 
algologists have been more ready to admit its affinities with the green 
Algae than mycologists. Fischer (’ 92 ), Schroeter (’ 99 ), Dangeard (’ 06 ), 
and Atkinson (’ 09 ) in particular derive the whole of the Phycomycetes 
from the Monadineae, Flagellatae, or Protococcoideae. The most recent 
and perhaps the most thorough exposition of this view is Atkinson’s. 
He vigorously combats the older idea that the Ancylistaceae and Chytri- 
diaceae have been derived from saprophytic Phycomycetes through the 
debasing influences of parasitism. This is clearly not capable of direct 
proof, and there are numerous instances to be drawn from other groups in 
support of either argument. He attaches great importance to the pheno¬ 
menon of diplanetism of the zoospores and traces its development from 
a simplified process in true Chytridiaceae, such as Rhizidiomyces , to its full 
perfection in the Saprolegniaceae. But a similar origin may be found for 
it amongst Algae, such as Chlorosphaera , Chlorochytrium , Ulothrix , &c., 
and it is in any case doubtful if the simplified process referred to has any¬ 
thing to do with true diplanetism. He does not attach much importance 
to the number of cilia on the zoospores as a basis of classification, nor does 
he consider that variability in this character need militate against the 
monophyletic view. A consideration of the conditions found in the Lepto¬ 
mitaceae in this respect certainly supports him here. Monoblepharis is not 
in his opinion a primitive Fungus, but may have developed its peculiar 
sexual processes independently, through change in the function of the 
zoospores. In the other Phycomycetes the sexual processes of Pythium 
and the Ancylistaceae are obviously allied to one another, but it is difficult 
to follow him when he connects these with the Chytridiaceae through Poly - 
phagtis and Zygorhizidium . He has possibly overlooked Dangeard’s (’00) 
account of the cytology of Polyphagus , which is monoenergid in the vege¬ 
tative and gametic stages. Zygorhizidium again appears to be monoenergid, 
while the sexuality of other Chytridiaceae is doubtful. Finally, after 
a review of the developmental characters of the two groups, Atkinson 
concludes that there are more points of similarity between the higher Phy¬ 
comycetes and the Chytridiaceae than between the former and any of the 
Algae which have been suggested as their probable ancestors. This is 
undoubtedly true so long as Mo 7 ioblepharis remains in the isolated position 
usually assigned to it by mycologists. 
Petersen (’10) also considers that it is possible to unite the Chytridia¬ 
ceae and Oomycetes in direct relationship, but he inverts the developmental 
line above suggested, and believes that the Chytridiaceae are degenerate 
members derived from the level of the Saprolegniineae (including the 
