THE SALMON FAMILY. 63 



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America, a remarkable fact in geographical dis- 

 tribution, perhaps explained only on the hypoth- 

 esis of the comparatively recent and Eurasiatic 

 origin of the group, which, we may suppose, has 

 not yet had opportunity to extend its range across 

 the plains, unsuitable for salmon life, which separate 

 the upper Missouri from the Great Lakes. 



The Salmon (Salmo salar) is the only black- 

 spotted salmonoid found in American waters tribu- 

 tary to the Atlantic. In Europe, where other 

 species similarly colored occur, the species may 

 be best distinguished by the fact that the teeth on 

 the shaft of the vomer mostly disappear with age. 

 From the only other species positively known 

 (Salmo truttd) which shares this character, the 

 true salmon may be distinguished by the presence 

 of but eleven scales between the adipose fin and the 

 lateral line, while Salmo trutta has about fourteen. 

 The scales are comparatively large in the salmon, 

 there being about one hundred and twenty-five in 

 the lateral line. The caudal fin, which is forked 

 in the young, becomes, as in other species of sal- 

 mon, more or less truncate with age. The pyloric 

 cceca are fifty to sixty in number. 



The following account of the coloration of 

 the salmon is from Dr. Day's " Fishes of Great 

 Britain : " 



" Color in adults superiorly of a steel blue, becoming 

 lighter on the sides and beneath. Mostly a few rounded 

 or ^-shaped spots scattered above the lateral line and 

 upper half of the head, being more numerous in the 

 female than in the male. Dorsal, caudal, and pectoral 

 fins dusky; ventrals and anal white, the former grayish 



