C05IP.VR.VTIVE STÜDT OF SCOMBROID FlSIinS. 383 



FOOD. 



Fisb lielonging t<j the geuus RastreUigcr seem to feed exclusively on 

 plauktou, chiefly copedpods. Scomher is also a plankton-feeder, hut its food 

 differs in different seasons and localities. In bays tlio 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 snrfiice-swimming and 

 school-making fishes, such as sardines, ancho^^cs, saurels, mackerels, sand-eels, &c. 



Timnies are also voracious, and most of them feed chiefly on plaukton in 

 the open sea. So far as I know, Neothunnus raitis seems to be the only speciej 

 which feeds near or in Httoral waters, and chiefly on fishes of moderate 

 size. When tmmies 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 fkli in the stomach. Once I found 

 a specimen of Leptdopus, 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 imderstand or rather imagine that 

 tunnies swallow fish sometimes from the head, and sometimes from the tail. 

 Tunnies feetl on Hving 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 plaukton 

 and immature fish, etc. may be foimd in the stomach of tunnies and bonitos. 

 I have obtained two fine specimens of Mda mda, very large phyllosoma of 

 Sci/Ilartis, immatm-e specimens of free-swimming stages of Scyllarus and Panu- 

 lirvs, Onijckoteicfhis, a great many specimens of Watasenia scintillam from the 

 mouth of Tokyo Bay, several species of Pleradis, Acanthurus (immature), Chielo- 

 don (immature), Maurollcus, Argylopelecus, Holoccntrum, Oslradon, Caesio, Exo- 

 coetm, Sergesks, Acardhephyra, 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 the foad, djtrting quickly 

 towards it, and swim away more or less downwards, therefore they are forced 



