6 TRANSACTIONS OF WAGNER 
ON THE LIFE HISTORY OF AN ECONOMIC CUTTLEFISH OF JAPAN 
may be estimated. A collection of specimens from Hokkaidé placed at my 
disposal provides, however, a key for estimation of the rate of growth, as seen 
in the following table, which is arranged according to the order of the months: 
Number of 
No. specimens Date of catch Mantle length 
i I July 5, torr 15.5-17.5 mm. 
ii 5 July 15, 1910 T7O-1O4 vise 
ili I Aug. 30, 1912 TOS He 
iv 3 Oct. 15, 1912 Igo-215 “ 
Vv 8 Nov. 1, git 2TO— 222i 
vi 2 Nov. 26, 1912 218-235 “ 
Vii 2 Dec. 14, 1914 205— 22 OMe 
Vili 7 Dec. 28, 1914 I95=2501 “ 
We see that the individuals caught in July are the smallest and those in 
December the largest, while gradual growth is going on in the intervening 
months, so that it is not difficult to find the rate of growth. This method of 
estimation could not be, however, extended and applied to the specimens 
from other localities, which could neither be obtained in so regular an order nor 
in so fresh a state. On the other hand, it has been found that the individuals 
grow heavier as the fishing season proceeds. The following is compiled from 
the returns from merchants of Sado and Tsushima who have long been dealing 
in the dried cuttlefish: 
DRIED CUTTLEFISH FROM SADO 
Average weight Month of catch 
ca. 15 grams May and June 
Cal, ip July and August 
CANS eee Sept. and Oct. 
CaaO Sipe Nov. and Dec. 
SAME FROM TSUSHIMA 
ca. 10 grams May 
Cale 20) ies June and July 
Canggu ys’ Aug. and Sept. 
2, Ge), Oct. and Nov. 
From the above table it is, therefore, also true that the animal is, in 
accordance with the estimation of the previous table, increasing in weight as the 
months proceed. This fact can not be proved to be true in some localities. 
In Toyama Bay, for instance, I got in the same month, April, specimens of 
every grade of age from very young ones to adult, and in Oki, on the contrary, 
there have been found grown individuals nearly all the year round. These 
