COMPARATIVE STUDY OF SCOMBROID FISHES. 
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bonitos, the cutaneous veins do not unite directly with the Cuvierian duct, but 
form hepatic portal veins. In bonitos the vascular plexus is also found in the 
haemal canal. Blood vessels in the air-bladder belong to the visceral vascular 
system. 
In primitive tunnies the kidneys are more or less ring-shaped, just behind 
the head, and around the pharyngeal muscles. In the other tunnies the 
kidneys are produced more or less behind, and in bonitos they are elongated 
nearly to the end of the abdominal cavity. Posterior portions of the kidneys 
lie chiefly on the roof of the abdominal cavity but, in the haemal canal too 
we find a continuous or sometimes small discontinuous masses of a kidney-like 
brownish substance with minute black spots. 
Skeleton firm, solid, and comparatively light. Skull firmly consolidated. 
The dorsal surface of the skull is entirely covered with the lateral muscle and 
there we find paired non-ossified portions, except in the genus Auxis. On 
the ventral side of the skull we find many deep grooves for the insertion 
of opercular muscles. The posterior end of the parasphenoid is more or less 
tubular. Subcranial cavity is very high. Lower piece of the postclavicle is 
not flat, the broad proximal part making nearly a right angle with the narrow 
distal part, and these two parts are in two different planes. The distal part 
is very short in many cases. Clavicular ligament is inserted in the first 
vertebra not to the skull. 
Vertebrae are compact and rich in grooves and ridges, so that they are 
light and firm. The total number of vertebrae is always 39, except in the 
genus Katsuivonus which has 41. They differ from each other in form, processes, 
etc, in different parts of the vertebral column. Neural and haemal processes 
are more or less laterally compressed. The first neural process is remarkably 
feeble. 
Fishes of this order seem to have their own temperature, more or less 
higher than the temperature of the water in which they live. They are 
voracious, pelagic fish, swimming very fast, and feeding on small fish, calamaries, 
and medium sized plankton. Found in temperate and tropical seas. They 
spawn in off-shore grounds and grow there. They are very energetic and 
powerful, therefore specially long and strong implements are required for catch¬ 
ing them. 
