118 MALACOP. ABDOM. SALMON FAMILY. 



considerably above the line of the junction between 

 the suboperculum and operculum.* In very young 

 specimens the tail is much forked, and this continues 

 to be the case, although gradually in a smaller de- 

 gree, till the fifth year, when the terminal line 

 becomes straight. The vertebrae are sixty in num- 

 ber, and the cascal appendages from sixty-three to 

 sixty-eight. 



The Salmon may be considered either as a salt or 

 fresh-water fish, according as we regard the one or 

 the other as most essential to its economy. They 

 invariably breed, as is well known, in fresh water, 

 while they find their most nutritious food, and 

 other conditions most favourable to their growth 

 and general health, in salt water. They begin to 

 enter rivers in spring, but the instinct which prompts 

 them to ascend towards the sources for the purpose 

 of reproduction, does not exert its full influence till 

 the end of autumn. They make their ascent chiefly 

 when the rivers are swollen by rains, generally ad- 

 vancing with some rapidity ; often it is supposed 

 at the rate of twenty-five miles a day,+ and so 

 strong is the impulse that urges them on, that they 

 overcome obstacles which, to an animal so formed, 

 we would be inclined to pronounce insurmountable. 



♦ British Fishes, vol. ii. p. 5. 



+ It has been estimated that, in a tranquil lake, Salmon can 

 swim at the rate of eight or ten leagues an hour, and twenty- 

 four feet in a second. This would give 86,400 feet in an hour, 

 a velocity which, if it could be continued, would enable theni 

 to make the tour of the globe in a few weeks. 



