452 
KAM AK ICH! KISHINOUYE: 
Long intermuscular bones on anterior precaudal vertebrae, which have 
their distal end at the surface of the body are found as far as the seventh 
vertebra. From the eighth vertebra backward some long intermuscular bones 
are also found, but they are not ossified in the middle portion. Intermuscular 
bones are well developed and are found on every vertebra, except those which 
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 are liable 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 hypaxial blood-vessels under the skin are equally 
well developed, teeth in both jaws only, vertebrae 20-21. Katsuwonus. 
Hypaxial blood-vessels under the skin are atrophied ; epaxial blood¬ 
vessels run just above the lateral median line of the body, 
teeth in both jaws, palatines, and sometimes on the vomer too, 
epihaemal spines well developed, vertebrae 20-19. Euthynnus• 
The first dorsal is not continuous with the second ; no foramen on the dorsal 
surface of the skull ; hypaxial bloodvessels under the skin are atrophied ; 
teeth in jaws only ; inferior foramen scarcely developed ; epihaemal spines 
well developed, long; vertebrae 20-19. Auxis. 
Genus Katsuwonus Kislfinouye. 
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 corselet. Teeth in jaws only, about 
forty in each. Gall-bladder long, nearly free from the liver, and runs along 
the dorsal side of the intestine. 
The cutaneous circulatory system is unique. A pair of cutaneous arteries 
branch just behind the insertion of the pharyngeal muscles as in the tunnies and 
other bonitos ; but passing through the kidneys the arteries turn outward and 
