COMPARATIVE STUDY OF SCOMBROID FISHES. 
349 
be the median superficial part, while in the Plecostei it seems to be the deeply 
seated “chiai” portion. In the Teleostei'the dark coloured portion gradually 
becomes broader and tliicker in the caudal portion, passing beyond the limit 
of the median superficial lateral muscle. I have examined and found that the 
dark red portion contains about 7 times as much blood as the other portion 
in Thunnus orientcilis, and about 15 times as much as in Parathunnvs mebachi. 
In Scomber joponicus the superficial red muscle contains almost 8 times as 
much blood as the other flesh, and in Cybiurn niphoniura the superficial red 
muscle contains 12-13 times as much blood as the ordinary flesh, which is 
nearly colourless. 
Histologically the dark red portion consists of uniform and fine fascicles, 
with many capillaries among them, and their mucle-fibres are faintly striated, 
more or less resembling the involuntary muscle-fibres. When the dried muscle 
of tunnies or bonitos are broken transversely, the chiai portion is rather rough 
0T 
and not lustrons, while the other portion is quite smooth and conchoidal. 
In the Katsuwonidae the chiai portion is better developed than in the 
Thunnidae, and both the epaxial and hypaxial parts of it reach the vertebral 
column, as the chiai portion has a wider base than in the tunnies, and as 
the segmental blood-vessels nourishing the portion originate on each side of the 
dorsal aorta and its plexus at 
two points, a little above and 
more or less below the verte¬ 
bral column. 
To the ventral side of the 
vertebral column a pair of 
cylindrical muscles are insert¬ 
ed to suspend the pharynx. 
These muscles run obliquely 
forwards from the vertebral 
column. These pharyngeal 
muscles are inserted into the 3rd 
and 4tll vertebrae in Scomber Fig. J. Cross section of the lateral muscle, show- 
japonicus, to tlie 4th in Raslrel- the latge fascioles of ,he or '’ in “ tJr P 01 “ 011 on the 
right side, and fine dark coloured fascicles of the dark 
liger chrysozonus, to the 3rd red portion on the left. 
Dark red portion Vascular plexus 
