426 
PACIFIC SCIENCE, Vol. VIII, October, 1954 
Fig. 37. a, Peyssonelia calcea: Habit of a specimen on a coral fragment, X 1.2. b, Hydrolithon reinboldii: Habit 
of a plant on a stone, X 1.5. c, Fosliella farinosa: Habit of plants on a "leaf” of Sargassum, X 1.4. 
This genus is characterized by its mono- 
stromatic hypothallium of cells 18-25 m long, 
its irregularly shaped and arranged perithal- 
lium cells, and scattered heterocysts. The 
specimen figured is a young one in which the 
low, rounded excrescences of older forms have 
not yet fully developed. The tetrasporangial 
conceptacles are about 350 fi in diameter as 
seen from above, low and convex. 
Lithothamnium erubescens var. subflabel- 
latum Foslie, in Weber van Bosse and Fos- 
lie 1904: 31, pi. 3, figs. 23-25 (Indonesia) 
Fig. 38^-c 
LOCAL DISTRIBUTION: On coral dredged 
from 2-3 m., Sta. 2 (11381); at low-water 
level in dark tideways, Sta. 9 (11322); on 
coral fragments, Sta. 13 (11439). 
This material seems clearly to agree with 
the type specimens of var. subjlabellatum as 
illustrated and described by Foslie. He main- 
tains that the species is variable and wide- 
spread in both the Atlantic and Pacific. The 
compressed branches and more or less flabel- 
late branch systems are distinctive. 
Lithophyllum trichotomum (Hey dr.) Le- 
moine 1929: 45; Dawson 1944: 267, pi. 55, 
fig. 2, pi. 58 , figs. 1, 4-6, pi. 60. Lithotham- 
nion trichotomum Heydrich 1901: 538 (Gulf 
of California) 
LOCAL DISTRIBUTION: On old coral frag- 
ments, Sta. 7 (11239). 
Both superficial and embedded tetraspor- 
angial conceptacles have been examined in 
