TRANSACTIONS OF WAGNER 
ON THE LIFE HISTORY OF AN ECONOMIC CUTTLEFISH OF JAPAN 
22 
to the coast. An actual case is represented by the government of Kéchi-ken, 
where it is recorded that good catches of the cuttlefish have often been made 
(fig. 9). The water strata in question lie, as seen in the section, in such a 
position as just mentioned and parallel with the contour line of the coast. 
It is not unreasonable to assume that this stratification of water is brought 
about by water strata of higher temperature, 7. e., Kuro-shiwo, pushed towards 
the shore of rapid inclination, as quite obvious in the section just referred to. 
From what has been stated, we do not hesitate to assume that the cuttle- 
fish occur in an ecologic relation which is brought about first of all by a water 
temperature of 10°-17° C., and that the reason a large body of the Tsushima 
Current is most profitable for cuttlefish fishing is due principally to its having 
this favorable temperature in moderate depth, 7. e., 50-100 fathoms. 
SUMMARY 
The facts stated above may be summarized as follows: 
(x) The cuttlefish inhabits, around Japan, on the whole the deeper parts 
of the coastal water (s. J.) of a definite temperature, so that in the Japan Sea 
it is thickly and widely distributed, its thickest distribution roughly coinciding 
with the extension of the Tsushima Current. In the Pacific Ocean, on the 
other hand, the distribution is usually limited to the deeper part of the oceanic 
margin, being brought about by the pressure of the oceanic currents like the 
Oya-shiwo and Kuro-shiwo. 
(2) The animal lives in the coastal waters chiefly because they have a 
temperature 10°-17° C. in proper depth, 50-100 fathoms, which affords the 
ecologic conditions most suited for the creature, but in exceptional cases the 
animal may be adapted to colder as well as to warmer water, as it is the case 
in northern and southern seas. 
(3) The horizontal migration of the cuttlefish is not so wide as from Kiu- 
shiu to Hokkaidé, but limited to a relatively small sea area. Its vertical 
migration takes place every day, extending from 50-100 fathoms in daytime 
to o-20 fathoms at the twilight of sunset and sunrise. During the daily verti- 
cal migration it seems to be not greatly affected by the change of water tem- 
perature met with in its travel through different water strata. 
(4) The cuttlefish becomes mature in a year. Young individuals live on 
floating micro-organisms, but when grown their food consists chiefly of living 
