COMPARATIVE STUDY OP SCOMBROID FISHES. 
443 
muscles and cutaneous arteries. Kidneys are prolonged posteriorly to the 
segment of the thirteenth vertebra. Ureters of both sides run side by side in 
the narrow portion of the kidneys, and become confluent just at the posterior 
end of them. 
Venules to the cutaneous vein are arranged in two alternate rows. Those 
of the exterior side pass over the cutaneous artery after joining many minute 
canals in the chiai plexus, and those of the inferior side unite to the cutaneous 
vein, just after joining minute canals. Arterioles from the cutaneous artery 
are arranged in two rows, one row on the remotest side from the accom¬ 
panying cutaneous vein, the other on the nearest side to the vein. Arterioles 
in the former row are nearly twice more numerous, but smaller than those 
in the latter row. Thus two sheets of vascular plexus are formed from 
groups of the two rows of both arterioles and venules. Cutaneous arteries are 
sent from the dorsal aorta just Mow the eighth vertebra. The posterior 
cardinal vein is insignificant. Segmental veins in the precaudal region and 
in some anterior caudal segments running towards the vertebral column are 
divided up into minute vessels there. Venous blood from these vessels seen 
to be taken up by capillaries of the dark red portion of the lateral muscle. 
Intestine longer than in the other Japanese tunnies, the third bend of it 
reaches nearly the first. Three lobes of the liver are thick, and triangular. 
Only a few, short, sparingly branched venules on the external surface of the 
middle and left lobes. Bulbous masses of vascular plexus are found on the 
inner side of the liver. These masses are slender and elongated, as the 
arteries in them take no part in the formation of the plexus, but run through 
them nearly straight. 
Preopercle higher than broad, and the interopercle is nearly as high as 
broad. Haemal spines in the precaudal region are rather long. Parapophyses 
well developed, long, flattened at the distal end. They are directed downward 
from the ninth vertebra, and form the haemal arch from the tenth vertebra. 
Caudal vertebrae not so well developed as in other tunnies. 
Back nearly black to greyish blue, sides silvery, and the iris silvery with 
bluish tint. Dorsal fins greyish, tinged yellow at the margin or the tip, 
finlets yellow. Pectorals are black at the dorsal side, but greyish at the 
ventral side, and the tip is sometimes washed with yellow. Yentrals are 
