430 
KAMAKICHI KISHINOUYE: 
towards the posterior end. The chiai portion is soft and poor in taste, and 
contains about seven to fifteen times as much blood as the other portion, 
estimating from the colour. 
Pylorus short, descending, runs along the inferior side of the stomach. 
Duodenum receives at the posterior side five or six dendritic canals carry¬ 
ing the tufts of pyloric coeca, and in bonitos two short tubes on the anterior 
side as well. These dendritic tubes greatly vary in length. Each terminal 
branch of these tubes ends with a tuft of coecal outgrowths of nearly equal 
size, and yellowish in colour. Each group of these tufts is covered with a 
membrane, and the whole mass of these tubes is covered with a thick 
membrane to form a compact mass. In these tubes w r e find a half digested 
mass of food, but in the yellow tufts we have not found it yet. 
Myotomes at the surface of the body are bent with acute angles at 5 points, 
so that we find more than ten concentric circles in the cross-section of the lateral 
muscle in each quadrant. There are three myotomes in the cephalic region, 
and generally we find an auxiliary intermusclar bone between the last two. 
Myotomes in the caudal peduncle seem to have been reduced in number. 
Moreover the terminal tendon of these myotomes are well developed, and may 
be distinctly seen at the outer surface of the muscle, when we remove the skin. 
The vascular system is very complicated and variable in different members 
of the group. Besides the cutaneous vascular system we find many peculiari¬ 
ties. It is remarkable that in the ancestral forms of tunnies the posterior 
cardinal vein does not pour directly into Cuvier’s duct. In these tunnies 
the principal veins uniting with the Cuvierian ducts are two large cutaneous 
veins carrying blood from the dark red portion of the lateral muscle, and the 
anterior jugular veins. The posterior cardinal vein is insignificant and communi¬ 
cates with lateral commissures at the caudal peduncle to the cutaneous veins 
mentioned above. In these forms hepatic portal veins form a massive plexus 
on the axial side of each lobe of the liver. In more advanced forms, 
however, the posterior cardinal vein is w’ell developed and united with the 
right Cuvierian duct. In these forms the venules flowing downwards from the 
dark red portions collect to the comparatively spacious haemal canal, and 
there they are divided into many short parallel transverse canals, which fill 
up the canal entirely, forming a solid mass in it. In still more modified 
