CHAPTER IV 

 SALMONID^E 



'HE Salmon Family. The series or suborder Salmonoidea, 

 or allies of the salmon and trout, are characterized as a 

 whole by the presence of the adipose fin, a struc- 

 ture also retained in Characins and catfishes, which have no 

 evident affinity with the trout, and in the lantern-fishes, lizard- 

 fishes, and trout-perches, in which the affinity is very remote. 

 Probably these groups all have a common descent from some 

 primitive fish having an adipose fin, or at least a fleshy fold on 

 the back. 



Of all the families of fishes, the one most interesting from 

 almost every point of view is that of the Salmonida, the salmon 

 family. As now restricted, it is not one of the largest families, 

 as it comprises less than a hundred species; but in beauty, 

 activity, gaminess, quality as food, and even in size of indi- 

 viduals, different members of the group stand easily with the 

 first among fishes. The following are the chief external charac- 

 teristics which are common to the members of the family : 



Body oblong or moderately elongate, covered with cycloid, in 

 scales of varying size. Head naked. Mouth terminal or some- 

 what inferior, varying considerably among the different species, 

 those having the mouth largest usually having also the strongest 

 teeth. Maxillary provided with a supplemental bone, and 

 forming the lateral margin of the upper jaw. Pseudobranchiae 

 present. Gill-rakers varying with the species. Opercula com- 

 plete. No barbels. Dorsal fin of moderate length, placed 

 near the middle of the length of the body. Adipose fin well 

 developed. Caudal fin forked. Anal fin moderate or rather 

 long. Ventral fins nearly median in position. Pectoral fins 

 inserted low. Lateral line present. Outline of belly rounded. 

 Vertebrae in large number, usually about sixty. 



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