COMrAK.\TIVE STUDY OP SCOMBROID FBHES. 391 



with oiir S|xx;ie3 or uofc. Tlie Hawaiinn species looks quite similar to our species 

 ill external characters ; but miuute examination is necessary for identificjitiou. 



Sd far as I know the plecostean fishes aie most rich in number of species 

 in uur waters. ,\mong our tunnies, Thunnm orienkdia is rather widely distribufc- 

 e<l. Ncothunniis raws is found only in Kyushj-u and the south-western part of 

 the Jrtimn Sea. In the Japan Sea we find only three species of tunny ; — 

 Thunnus orimtalis, Neothwimis macropterus, and Ncothunnus rar us. The latter 

 two species, however, are very few in numlier, and there is no regular fishing 

 for them. .-Ul the species of tunuies found in the Japan Sea Uve near 

 the surface and approach the coast. The tunnies inhabiting oflf-shore grounds 

 and descending into rather deep strata of water have not yet been found in the 

 Japan Sea. Tliis is most probably due to the fact that the temperature of 

 the sea is too cold for these species. Bonitos are also foimd in tlie Japan 

 Sea ; but rathei' few in number, and Euilajnnus yaito is very rare. 



Tlie scombroid fishes with the air-bladder Live generally a wider range 

 of vertical disti'ibution than those without it. The latter group of fish is 

 often restiicted to the sm-face of the water. Or they are near the surface 

 in some seasons, and descend to deeper layera of the sea in other seasons. 

 They can not change their abjde suddenly, but wlieu the change Is gradual 

 they can endure it. Most scombroid fishes swim in shallow strata of 

 water, but timnies generally, especially Parathunnns mebac/d, are found in 

 deeper strata of water than binitos. ]3onitos and voracious species of the 

 Cybiidae frequent the surfac« of the sea and are readily atti'acted to artificial 

 baits. These fishes are rarely found in deeper sti'ata tloan about 80 m. 



The scombroid fishes are foimd in warm seas, the majority of them Ije- 

 longing to the tropical and subtropical regions, and most of them are very widely 

 distributed. They swim very fast in search of prey, and many of them have 

 then- oAvn blood-temperature as higher animals. Our common mackerel and the 

 striped bouito are cosmopolitan species. The long -finned tunny ( Tlmnmcs germo) 

 and Acanthocyhium solandri, too, seem to be widely distiibuted, though a 

 critical determination of the species fi-om dififerent pai-ts of the world lias not 

 yet Ijeen made. The following tables illustrate the distribution of scombroid 

 fishes in om* waters and adjacent regions. 



