308 KAlIAKICHI KISHINOTTE : 



suppression of some posterior spines, and in these cases tLe first doi'sal is 

 sli(jrt Imt rather high, higher than the second doi-sah The first dorsal of the 

 Scc)mbrida3 originates from the myotome of the second vertebra, while tliat of 

 the other so-called scombroid fishes originates from the myotome of the fii-st 

 vertebra. Therefore the origin of the first doi'sal in the Scombridae 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 Scombridne the spines 

 of the fii-st doi'sal are very feeble, and the fii'st spine is shorter than the 

 second, which is generally the longest (figs. 28, 29). In the Cybiidse the first 

 dorsal is generally low, long, mostly black, and its outline is more or less 

 convex, gradually descending b:ickwards (figs. 31-37, 61, 62). The fii'st spine 

 is not the longest as in the Scombrid». The first dorsal of Acaiithocyhium 

 solandri differs &'om that of allied fishes in baiug broad and of nearly the 

 same breadth throughout (fig. 31). In Cyhiiun the height of the fii-st dorsal 

 is 1/4-1/3 the height of the body. In the Plecostei the first dorsal is 

 generally high and the outUue of its doreal 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 Kcdsuiuonvs the height of the fiist dorsal is best develo^jed. The 

 longest spine is about 3/5 the height of the body. In other bonitos and 

 most tunnies the height of the fii-st dorsal is contained about twice in the 

 height of the body. 



The second dorsal and anal are neaily equal in form and size. The 

 former precedes the latter one myotome in Sccnnber and Cyhium, and alK)ut 

 three myotomes in the Thunuidse. Fin-rays of these fins grasp the distal 

 segment of the intei-spinous bone between the proximal ends of thek lateral 

 halves. In the Scombridse these two median fins are resiiectively smaller 

 than the spinous dorsal, and fin-rays of these fins are feeble and transversely 

 ai-ticulated. In Scomher moreover an isolated spine is found before the aual 

 as in the Caraugidas. In the Cybiidse these two fins axe pretty well developed» 

 generally higher than the fii-st dorsal, and their fin-rays are thick and 

 nonai-ticulated. As some anterior fin-rays of these fins are well develojied, 

 their form becomes falcate. They are pretty large, well developed in Cyhium 

 hcyreanum (fig. 35) and C. guttatum (fig. 61); but are poorly developed and 



