308 
KaMAKICHI KISHINOUYE : 
suppression of some posterior spines, and in these cases the first dorsal is 
short but rather high, higher than the second dorsal. The first dorsal of the 
Scombridæ originates from the myotome of the second vertebra, while that of 
the other so-called scombroid fishes originates from the myotome of the first 
vertebra. Therefore the origin of the first dorsal iu the Scombridæ is well 
behind the origin of the pectoral fin, while in the other groups the former 
and the latter lie nearly in the same vertical. In the Scombridæ the spines 
of the first dorsal are very feeble, and the first spine is shorter than the 
second, which is generally the longest (figs. 28, 29). In the Cybiidæ the first 
dorsal is generally low, long, mostly black, and its outline is more or less 
convex, gradually descending backwards (figs. 31-37, 61, 62). The first spine 
is not the longest as in the Scombridæ. The first dorsal of Acanthocybium 
solandri differs from that of allied fishes in being broad and of nearly the 
same breadth throughout (fig. 31). In Cybiurn the height of the first dorsal 
is 1/4-1/3 the height of the body. In the Plecostei the first dorsal is 
generally high and the outline of its dorsal posterior side is concave, and its 
first spine is always longest and thickest, the following spines, though 
decreasing rather rapidly in length are also strong (figs. 43-48). In the 
genus Katsuwonus the height of the first dorsal is test developed. The 
longest spine is about 3/5 the height of the body. In other bonitos and 
most tunnies the height of the first dorsal is contained about twice in the 
height of the body. 
The second dorsal and anal are nearly equal in form and size. The 
former precedes the latter one myotome in Scomber and Cybium, and about 
three myotomes in the Thunnidæ. Tin-rays of these fins grasp the distal 
segment of the interspinous bone between the proximal ends of their lateral 
halves. In the Scombridæ these tw r o median fins are respectively smaller 
than the spinous dorsal, and fin-rays of these fins are feeble and transversely 
articulated. In Scomber moreover an isolated spine is found before the anal 
as in the Carangidæ. In the Cybiidæ these tw r o fins are pretty well developed, 
generally higher than the first dorsal, and their fin-rays are thick and 
nonarticulated. As some anterior fin-rays of these fins are well developed, 
their form becomes falcate. They are pretty large, w r ell developed in Cybium 
koreanum (fig. 35) and C. guttatum (fig. 61); but are poorly developed and 
