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as long as broad, slightly inflated at joints; 
branches and pinnae alternate and distich- 
ous; the lowermost cell of branches quadrate, 
with no pinna, the next cell with a pinna on 
the adaxial side; pinnae simple or divided, 
linear-lanceolate, slightly incurved, blunt at 
the apex, 22—24 /x diam. at the apical cells, 
with a simple or divided pinnula on the abax- 
ial side of the lowermost cell of a few lower 
pinnae in the lower branches; chromato- 
phores numerous, short slender bands; spo- 
rangia sessile, usually secund on the adaxia] 
side of pinnae and pinnulae but rarely also 
scattered on the abaxial side of pinnae, el- 
lipsoidal, 70-106 g long and 50-78 g broad, 
with many spores; antheridia secundate on 
the upper side of the ultimate ramuli; pro- 
carps subterminal; cystocarps terminal, with 
no involucre; gland cell absent. 
Japanese name: Tohyama-kusudama 
(nom. nov.). 
Type: Growing on rocks, Mera, Prov. 
Boshu. T. Inaba 402, Apr. 10, 1944 (Her- 
barium, Dept. Fish., Hokkaido Univ.). 
In 1917, Yendo (1917: 91) referred a 
plant of Pleonosporium from Cape Inubo to 
P. venustissimum ( Kiitz. ) De Toni, no doubt 
following the specific conception entertained 
by De Toni (1903), who had amalgamated 
P. vancouverianum J. A g. with this species. 
Kylin (1925: 57) has disagreed with De 
Toni’s view, stating that: ' Kiitzing’s figure 
(Tab. Phyc., 12: pi. 1) shows that in C. ve- 
nustissimum A the side branch from the under- 
most cell of a branch often occurs on the 
upper side, but in PL vancouverianum it al- 
ways occurs on the lower side.” If that be 
the case, there arises a question as to the 
nature of the side branch under consideration 
in Yendo’s plant. 
‘As a species of Callith amnion. 
