OBSERVATIONS ON IIOTARU-IKA WATASENIA SCINTILLANS. 
8i 
iii) In 6 specimens out of 50 females caught with the same net, April 
29, the stomachs contained rich and rather fresh contents, consisting mainly 
of small fishes, Mysis sp. and pelagic Copepocis" {^Corjcaeus s^. & Oncaea 
sp. etc.). 
iv) 3 specimens out of 10 females obtained, July 26, had some iridocyte-like 
substance, some pieces of the back bone of a fish and 2 pieces of its skull. 
Besides, there were also found in the stomach some plankton-animals 
which were indistinguishable on account of their maceration. 
Judging by the facts stated above, it seems that the animals having food 
in the stomach are few in percentage, and we may say that the Hotarn-ika 
caught during the night at Namerikawa and vicinity are not of those kinds 
which visit the sea coast for the purpose of getting food, i. e. feeding migration. 
4. Seasonal Changes of Liver Content. 
The fresh female Hotarn-ika in the fishing season are at a glance distin- 
guishable from other kinds of cuttle-fish, being reddish in colour. This colour 
is caused by the liver, which is seen externally through the transparent mantle. 
If the liver be dissected in water, many reddish oily globules (reserved nutri- 
ment?) come up to the surface of the water. And if the liver be split into 
small pieces with a dissecting needle and looked at under the microscope, it is 
easily seen that the same reddish substance is also contained in the tissue. But 
in the males which were taken at the same time with the females, the liver sliows 
no such reddish hue, but is gray and provided with only a small amount of 
such reddish oily substance in the tissue. This difference in colour between 
the sexes is so easily distinguishable in the spring time that above 10,500 
specimens were assorted into male and female by 5 or 6 students of the Fishery 
Institute in about one hour and a half. 
But, on my second visit, which lasted from the middle of August till late 
September, it was soon observed that the reddish hue of the liver of the female 
was changed into a gray hue resembling that of the male in spring. The 
1) I owe the identification of the Copepoda to Mr. S. Kokubo, to whom I expiess my thanks 
for it. 
