148 SALMON AND TROUT. 
below, as the keeper, who was watching, said, ‘like a great 
porpoise.’ 
As to the question, ‘Will salmon live and thrive entirely in 
fresh water—that is, in lakes and ponds which have no com- 
munication with the sea?’ some observations will be found in 
previous editions. 
The principal characteristics of the true salmon are : 
Length es head compared with whole length of fish as x to 5. Body ac Ne 
dorsal and abdominal line about equally convex. Lateral line near middle of 
body, dividing it about equally. Fleshy portion of tail slender. Scales, mode- 
rate sized, oval, and thin, easily removed when young, adherent when old. 
Teeth, stout, pointed, and curved, one line on each side of upper jaw, one line 
on each bone of palate, one line on vomer or central bone in roof of mouth 
when quite young (loses a large portion on first visit to salt water, and gradually 
all, or all but one or two on most forward point of bone), on line one each side 
of lower jaw, one line on each side of tongue (occasionally two lines on each 
side of tongue). 
Fin rays: D. 13: P. 12: V.g: A.g: C. 19. Vertebrze, 60, 
THE BULL TROUT (Salmo eriox). 
Although differing in many respects from the true salmon, 
and constituting, of course, a distinct species, yet in many of 
its habits, if not, indeed, in all, the bull trout bears so close a 
resemblance to the latter fish that the history of the one may, 
to a great extent, be taken as the history of the other, and all 
the laws relating to salmon apply equally to the bull trout and 
their young, under whatever local names tliey may be known. 
Like the salmon, the bull trout ascends rivers for the purpose 
of spawning, deposits its ova on similar spawning grounds, and 
after the process returns to the sea to restore its exhausted 
energies and increase in weight and bulk. So far as I am 
aware nobody has actually verified—that is by the same absolute 
means as in the case of the salmon—the periodical growth-rate 
of the bull trout between its various migrations. But as I have 
caught several hundreds of bull trout myself in the Usk averag- 
ing from four up to twenty pounds and never remember to 
have caught one of much less than the first-named weight, it is 
only reasonable to conclude that this is the size at which they 
