The so-called "keels" which project on both sides of the tail are not con- 

 spicuous in the cybiids, and they are also low in the bonitos and tunas. 



When we look at the interesting markings of the Plecostei, we find that in the 

 species of Katsuwonidae which have slanting markings on their backs the young fish 

 have transverse markings of the so-called transverse ring type,, The part of these 

 markings which lies below the lateral line disappears later leaving the so-called 

 cloud pattern. On the other hand, the black tuna and yellowfin, which also have 

 transverse rings when young, lose the markings on their L>acks aa they gn^' larger, 

 and only gray markings are left on the anterior part of the belly. 



On katsuwonids such as the skipjack, which have longitudinal markings, it 

 seems that only longitudinal stripes appear from the very beginning. Furthermore, 

 among the thunnids there are some like the albacore and the koshlnaga [Neothunnus 

 rarus (Kishinouye)], which probably never have transverse rings but only longitudinal 

 markings on the belly 



When one looks at juvenile hagatsuo f Sarda orientalis j. the fish. which most 

 closely resembles the Plecostei, at about 9.6 inches in length, one finds that they 

 have transverse rings which are broader than those of the katsuwonids as well as 

 several slanting lines on the dorsal portion of the body. Later these slanting lines 

 persist while the transverse rings disappear. 



11 



