Rotatoria of Korea — Yamamoto 
157 
1894 Anuraea ekhwaldi Levander, Soc. Fauna 
Flora Fennica, Acta 12: 62. 
Total length, 120 /r. 
This brackish-water species was found in 
every part of Lake Kandong-po (9^, h, c). 
The hind process is absent. Both the punctate 
and reticular sculptures are remarkable. In the 
dorsal lorica, the frontal plate is very short 
c. 10 m), but the first carinal plate is remark- 
ably long (c. 75 m)- 
Keratella serrulata (Ehrenberg, 1838) 
PI. 2, Fig. 20 
1838 Anuraea serrulata Ehrenberg, Infusions- 
thierchen, p. 508. 
Total length: 195 m (from the frontal notch 
to the posterior end, 130 \x, length of the 
ventral plate, 120 yl). Width: frontal end 98 
y, greatest, 112 y, hind end, 54 y\ frontal 
processes: central, 65 y, sublateral, 22 y, later- 
al, 25 y. 
Both the punctate and reticular sculptures 
are remarkable in the dorsal plate. 'The last 
central plate is hexagonal, and from its pos- 
terior corner a central line runs posteriorly. 
Both posterior corners project slightly. The 
central pair of the frontal processes are long 
and stout, bending downward remarkably 
near the tip. This is a characteristic species of 
dystrophic water. Skadowski (1923) has found 
this species in moorland waters, in which the 
pA values ranged from 3.2 to 4.5. The pA 
value of the present locality (1^) measured as 
high as 6.3. 
DISTRIBUTIONAL RELATIONSHIPS 
As already noted, in the western region 
only a collection of potamoplankton was 
made, on the river Taidong-gang (16), where 
only five rotatorian species were found. This 
number is not small for a collection from a 
river, but there are very few individuals of the 
species, four of which were found in three 
other regions. Therefore, the fauna of the 
western region should not be considered here. 
The species common to the three other re- 
gions number eight, or less than 10 per cent. 
In general, these species are well known to be 
widely distributed animals. They are all pe- 
lagic except Diurella tigris. The frequencies of 
occurrence are as follows: 
Polyarthra trigla 
12 stations 
Keratella cochlearis 
10 stations 
Keratella cochlearis var. tecta 
7 stations 
Asplanchna priodonta 
9 stations 
Filinia longiseta 
6 stations 
Synchaeta ohlonga 
4 stations 
Trichocerca longiseta 
4 stations 
Diurella tigris 
3 stations 
The number of species peculiar to any one 
region of northern, middle, or eastern Korea 
are 17, 25, and 19, respectively. The total pe- 
culiar to one region, 61, is three fourths of the 
total number. Of the 13 species remaining, 8 
are found both in the middle and eastern re- 
gions, 3 others are found both in the northern 
and middle regions. One species {Lepadella 
ovalis) is found in both the northern and the 
eastern regions. 
The collections in northern Korea were 
made chiefly in summer. Seventeen species 
obtained from this region are, without excep- 
tion, found only from Tai-taik. Only one 
from Tai-taik, Keratella quadrata, is also found 
in the collection from Puchon-ho, and in the 
Taidong-gang of the western region. This 
suggests that the conditions of Tai-taik differ 
greatly from those of any other waters visited. 
The occurrence of Keratella cochlearis var. ma- 
cracantha is worthy of note as this collection 
was made in midsummer and this has been 
considered heretofore to be a winter form. 
In Tai-taik 23 species of Rotatoria were 
found, i.e., 8 from the pelagic, 18 from the 
littoral, and 3 among the mosses of the mar- 
ginal region. 
In a work on the plankton of Lake Puchon- 
ho, the present author (1941) has noted that 
at the early stage of the development of the 
reservoir many heleoplankters such as Cono- 
chilus hippocrepis were found, but after several 
years the condition of the water so changed 
that Synchaeta spp. and Keratella quadrata ap- 
