158 
Q C.v. tectso O VaJ,^^t-.wo»i5tiro5a. 
P C. f .mbrdxacntha^ Q vaLgd,f tropica^ 
X) c. ^/.m^£.r^y 0 ^^K 0 serrulate 
Fig. 2. Occurrences of the genus Keratella in Korea. 
peared. In July, 1941, Asplanchna priodonta 
was the predominant species, being especially 
abundant in the epilimnion. The nine species 
reported from this reservoir, excepting Kera- 
tella quadrata, are common to the middle and 
eastern regions. 
In the middle region, three of the samplings 
were made by Sato from localities in and 
around Seoul. Among them, one from a pool 
at Shindo-cho (4) contained only a single 
species, Conochilus hippocrepis. The collections 
from a pool at Shochudan (3) and from Ei- 
toho (5) contained 11 species each. A remark- 
able condition common to these two localities 
PACIFIC SCIENCE, Voi. VII, April, 1953 
is the richness of species belonging to the 
family Brachionidae, i.e., eight from the for- 
mer and six from the latter. It is particularly 
noteworthy that species of a warm-water type 
are found here, e.g., Brachionus forficula in the 
latter and Keratella valga in both localities. 
As potamoplankton of the Hang- gang (6), 
only a single species {Keratella cochlearis) was 
found, but Sato (1939) has reported two spe- 
cies, Asplanchna priodonta and Testudinella pa- 
tina, from the same river in winter. 
Besides our collection from Seiko (7), those 
taken by Kawamura on June 2, 1936 (7^), 
were examined. Notwithstanding the fact that 
the season of collection was quite different, 
11 species found in early summer were all 
included among the 18 species collected in 
Fig. 3. Occurrences of the genus Polyarthra in Korea. 
