Pacific Species of Antithamnion — TOKIDA and Inaba 
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Fig. 15. Pleonosporium Tohyamanum Tokida and Inaba, sp. nov.: a, two sporangia; b and c, apical 
portions of fertile pinnae, showing carpogonial branches: 1, 2, 3, and 4, carpogonial branch cells; 
sc, supporting cell or fertile pericentral cell, provided with a carpogonial branch and a sterile cell; 
ac, apical cell of the pinna, a, X 150; b and c, X 344. 
In the spring of 1944, the junior author 
collected a Pleonosporium at Mera, Boshu 
province, not far distant from Cape Inubo. 
In general characters it resembles the two 
species mentioned above, but is not identical 
with either of them, differing in certain re- 
spects, especially in the entire absence of the 
side branch or pinna on the lowermost cell 
of a branch. The side branch on the cell next 
to the lowermost one arises always on the 
adaxial side of the branch. In this respect 
our plant shows a resemblance to P. vancou- 
vertanum rather than to P. venus tissimum. 
According to the brief description by Yendo, 
the main branches of his plant seem to have 
somewhat longer cells than those of ours. As 
to the rhizoidal filaments. Yendo describes 
merely those growing downward from the 
basal cell of the pinnae, while our plant has 
in addition lateral rhizoidal filaments which 
issue from the lower segments of the main 
axis and which rarely become as thick as the 
main axis (Fig. 13 b) . It is quite probable 
that our plant is identical with Yendo’s, but 
at present we cannot settle the question as 
we have had no chance to examine Yendo’s 
original specimen. In any event, we believe 
the plant in question is new to science, and 
