COMPARATIVE STUDY OF SCOMBROID FISHES. 
383 
FOOD. 
Fisli "belonging to the genus Rastrdliger seem to feed exclusively on 
plankton, chiefly copedpods. Scomber is also a plankton-feeder, but its food 
differs in different seasons and localities. In bays the fish is omnivorous, and 
feeds near the bottom ; but in the open sea it seems to feed near the surface. 
Fishes of the Cybiidae are voracious, and feed chiefly on surface-swimming and 
school-making fishes, such as sardines, anchovies, saurels, mackerels, sand-eels, &c. 
Tunnies are also voracious, and most of them feed chiefly on plankton in 
the open sea. So far as I know, NeotJiunnus rarus seems to be the only species 
which feeds near or in littoral waters, and chiefly on fishes of moderate 
size. When tunnies devour fish of somewhat large size, they break their verte¬ 
bral column near the neck or the tail, probably with their strong jaws, most 
likely to prevent movement of the engulfed fish in the stomach. Once I found 
a specimen of Lepidopus, about two metres in length, in the stomach of a tunny. 
It was found bent several times in the stomach. A full-grown tunny can swallow 
bonitos or young tunnies under 40 cm in length. The smallest animal found 
in the stomach of a full-grown tunny measured about 5 mm. in length. Judging 
from the position of food in the stomach, we understand or rather imagine that 
tunnies swallow fish sometimes from the head, and sometimes from the tail. 
Tunnies feed on living animals, but they are enticed by deceased or preserved 
baits as well, and even to artificial batis when they are moving in water. The 
food of bonitos is nearly the same as that of tunnies. However, bonitos can 
not swallow large animals as tunnies do. Many interesting forms of the plankton 
and immature fish, etc. may be found in the stomach of tunnies and bonitos. 
I have obtained two fine specimens of Mda molct, very large phyllosoma of 
Scyllarus, immature specimens of free-swimming stages of Scyllarus and Panu- 
lirus, Onychoteuthis, a great many specimens of Watasenia scintillans from the 
mouth of Tokyo Bay, several species of Pteraclis, Acanthurus (immature), Ghaeto- 
don (immature), Maurolicus, Argylopelecus, Holocentrum, Ostracion, Gaesio, Exo~ 
coetus, Sergestes, Acanthephyra, different kinds of Heteropoda and Pteropoda. 
Scombroid fishes feed on swimming animals, and do not prey at the bottom, 
nor at a wall nearly perpendicular. They swallow tfre food, darting quickly 
towards it, and swim away more or less downwards, therefore they are forced 
