shown:

[Footnote 4: The parts referred to in the key may be defined
as follows: Anal fin, the single fin on the median line of
the body, between the vent and the tail; gillrakers, bony
protuberances on the concave side of the bones supporting
the gills; branchiostegals, small bones supporting the
lower margin of the gill cover; pyloric coeca, worm-like
appendages of the lower end of the stomach; vomer, a bone in
the front part of the roof of the mouth.]

I. Anal fin elongate, with 16 rays; gillrakers 9 + 14; branchiostegals
15 to 19; pyloric coeca 140 to 180; caudal fin considerably
forked; average weight about 20 pounds, maximum 100 pounds.
Quinnat salmon.

[Illustration: Chinook or quinnat salmon (_Oncorhynchus
tschawytscha_)]

II. Anal fin short, with 9 to 12 rays; gillrakers 8 + 12:
branchiostegals 11; pyloric coeca less than 70.

1. Teeth on vomer little developed, those on shaft few and
deciduous; scales large, about 120 in lateral series;
pyloric coeca 65; caudal fin emarginate; average weight
15 pounds, maximum 40 pounds.
Atlantic salmon.

[Illustration: Atlantic salmon (_Salmo salar_)]