452 KAMAKICHI KLSHEs'OrYE: 



Long intermusciJfir bones on anterior precauflal vertebrae, which have 

 their distal end at the snrfat« of the body are found as far as the seventh 

 vertebra. From the eighth vertebra backward some long iutermiisctdar Ixines 

 are also foimd, but they are not ossified in the middle portion. Intermuscular 

 bones are well developed and are found on every vertebra, except those wliich 

 have the lateral keel, and behind the attachment of intermuscular bone there 

 is a pointed tubercle in the vertebra. 



External and internal portions of the clavicle are perpendicular" to each 

 other. 



Below each eye an oval black spot is generally found. This colour spot 

 is distinct, especially in the genus Auxis. 



Fishes of this family feed chiefly on small fishes and medium sized 

 plankton. They ai'e Uable to perish sooner than those of the Thunnidae. 



Key to the genera of the Katsuwonidae. 



The first dorsal is continuous to the second, a pair of foramen on the dorsal 

 surface of the skull, inferior foramen of vertebrae well developed, thus 

 the so-called trellis is formed. 



Both epaxial and liypaxial blood-vessels under the akin are equally 



well develoijed, teeth iu both jaws only, vertebrae '20-21 KatstMomis. 



Hypaxial blood-vessels under the skin are atrophied ; epaxial blood- 

 vessels run just above the lateral median line of the body, 

 teeth in lx)th jaws, palatines, .and sometimes on the vomer too. 



epihaemal spines well developed, vertebrae 20-19 Euthi/nnus- 



The first dorsal is not continuous with the second ; no foramen on the dorsal 

 surface of the skull ; hypaxial bloodvessels xmder the sidn are atrophied ; 

 teeth in jaws only ; inferior foramen scarcely developed ; epihaemal spines 

 well developed, long ; vertebrae 20-19 Auxis. 



Genus Katsuwonus Kishiuouye. 

 Katsuwonus, Kishinouye, Sui. Gak. Ho. I, 21, 1915. 



Body plump, rounded in cross-section, and we find a few minute scales 

 scattered in the thick skin, outside of the coreelet. Teeth in jaws only, about 

 forty in each. Gall-bladder long, nearly free from tlie hver, and runs along 

 the dorsal side of the intestine. 



The cutaneous circulatory system is unique. A pair of cutaneoiH ai"teries 

 branch just behind the insertion of the pharyngeal muscles as in the tunnies and 

 other bonitos ; but passing tlirough the kidneys the arteries tm-n outward and 



