The vertical distribution of freshwater planarians in the Suzuka Mountains and the adjacent district in the north-eastern part of the Kinki Region in Honshu(Lat. 34°45′N. to Lat. 35°30′N. and Long. 136°10′E. to Long. 136°40′E.)is reported. The Suzuka Mountains bestride on the boundary between Shiga Prefecture and Mie Prefecture(the south-east of Lake Biwa-ko) ; most of the mountains are over 1000 metres in elevation(the highest peak, Mt. Amagoi-dake, is 1238 metres above sea level). Mt. Ibuki, 1377 metres high, is situated north-east of Lake Biwa-ko. The main river systems in the eastern part of the area surveyed are the Makita, Machiya, Asake, Mitaki, Utsube and the Susuka. They discharge into Ise Bay facing the Pacific Ocean. The river systems in the western part of the area surveyed(the Amano, Echi, Hino and the Yasu)drain into the Lake. The surveys were made from 1951 to 1967. In the area surveyed, two species of freshwater planarians, Dugesia japonica ICHIKAWA et KAWAKATSU and Phagocata vivida(LJIMA et KABURAKI), were found. D. japonica was most common at the stations both in the plain and the mountainous districts(below the altitude of about 1060 metres). Ph. vivida was found only at the stations of cold-water within the altitude range from about 600 to 1140 metres or more. The type of the vertical distribution in the area surveyed is J-JV-V(J : D. japonica; V : Ph. vivida).
This report deals with migration, pair formation, nest building, egg laying, incubation, hatching, feeding, fledging and family stage of the Eastern Great Reed Warbler during 1965 to 1966 along the reed bed of the Chikuma River, Zenkoji basin, Nagano Prefecture.
The distribution of marine-algae in Fukaya Canal, which connects Ago Bay directly to the Pacific Ocean, and in its vicinity was studied. It was found that the vegetation with respect to the zonation and the number of species change gradually through the canal in the sublittoral zone, but in the littoral zone they change remarkably, especially at the canal exit.
The author reported in his previous paper(MAKI, 1966a)that the under-yearling population of Gnathopogon caerulescens tends to fluctuate yearly towards the period between winter and spring during which they carry on their wintering and spawning activities, respectively. To confirm the findings stated above, some efforts were made in analyzing the various fishery records (1960-1966) of the fishery cooperations around the lake. The records of daily catch obtained with various gears in different periods, i.e., the spawning trap in spring, the trawl net in winter and the gill net in spring and late summer, were compared with each other. A statistical analysis of the data revealed that the amount of the total catch depends on the number of fishing efforts in the case of the spawning trap and gill net fisheries, since the correlation coefficients between the total fishing days and total catch by these two gears were all significant at one per cent level, i.e. 0.861 for the spawning trap, and in the case of gill net, 0.929 in spring and 0.877 in late summer, respectively. Thus, the catch per day by each fishing gear was used in this study as an index of the biomass of the population. The correlation coefficient between the index of the biomass of the spawners and that of the under-yearling population in early winter was 0.846(significant at one per cent level). While, no correlation was observed between the index of the biomass of the underyearling population in early winter and that in early spring. Rather parabolic relation which may indicate the presence of density dependent mortality was observed between the early spring index of the under-yearling population and the late summer one of the same population. The correlation coefficient between the index of biomass of the yearling population in late summer and that in the next spring was 0.909 with the significance at one per cent level. The "wintering" of the yearlings is not important for the annual fluctuation of the population. The indices of the under-yearlings in early winter obtained from three different areas of the lake fluctuate annually with a significant correlation from 1960 to 1966. Much the same tendency was observed between the late summer indices of the yearlings from 1960 to 1963 from two areas. These results suggest that the annual fluctuations of catch per unit effort occurred in a similar pattern at various fishing grounds around the alke. However, a different situation was observed among the early spring indices, which suggested that the mortality rate during the wintering period differed from one area to another.
In most insect populations, the pattern of their spatial distributions conforms to the negative binomial series. In some of these cases the degree of aggregation represented in terms of exponent k is stable, while in others it decreases with the increase of the density. The theoretical relation between the value of k and the population density was examined and discussed with regard to the four processes leading to the negative binomial distribution : true contagion, heterogeneity in the probability of occurrence, compounding of POISSON and logarithmic distributions, and immigration-birth-death process. In the first two processes a common k may be obtained within a certain range of density, but in the third process k changes proportionately with the density. In the last process k is stable if the rates of immigration and birth change at the same ratio as the density increases.
To make a series of bioeconomic studies of the ant species, Formica japonica MOTSCHULSKY, many nests were excavated from 1961 to 1965 in Tokyo, Odawara and Yokohama, Japan. This is the first report of the series describing the nest structure and seasonal change of the colony members. The gallery of the nest extends to the depth of 3m, where the soil is very hard and has fine clefts containing much capillary water. In winter the net-work of the galleries and chambers near the soil surface are plugged by the deposition of soil. Ants creep down to the deeper portions, and make themselves to still masses. Hibernating ant workers are corpulent by developed fat body, but have little crop sap. No brood is seen in winter. In summer workers at upper portions forage out to the ground surface and those in lower portions stay in the nest. The first batch of brood become reproductive castes and the later batch grows into workers. These phenomena are described in detail.