There are five species of salmon (_Oncorhynchus_) in the waters of the North Pacific, all found on both sides, besides one other which is known only from the waters of Japan. These species may be called: (1) the quinnat, or king-salmon, (2) the blue-back salmon, or redfish, (3) the silver salmon, (4) the dog-salmon, (5) the humpback salmon, and (6) the masu; or (1) _Oncorhynchus tschawytscha_, (2) _Oncorhynchus nerka_, (3) _Oncorhynchus milktschitsch_, (4) _Oncorhynchus keta_, (5) _Oncorhynchus gorbuscha_, (6) _Oncorhynchus masou_. All these species save the last are now known to occur in the waters of Kamchatka, as well as in those of Alaska and Oregon. These species, in all their varied conditions, may usually be distinguished by the characters given below. Other differences of form, color, and appearance are absolutely valueless for distinction, unless specimens of the same age, sex, and condition are compared. The quinnat salmon (_Oncorhynchus tschawytscha_),[7] called quinnat, tyee, chinook, or king-salmon, has an average weight of 22 pounds, but individuals weighing 70 to 100 pounds are occasionally taken. It has about 16 anal rays, 15 to 19 branchiostegals, 23 (9 + 14) gill-rakers on the anterior gill-arch, and 140 to 185 pyloric cœca. The scales are comparatively large, there being from 130 to 155 in a longitudinal series. In the spring the body is silvery, the back, dorsal fin, and caudal fin having more or less of round black spots, and the sides of the head having a peculiar tin-colored metallic luster. In the fall the color is often black or dirty red, and the species can then be distinguished from the dog-salmon by its larger size and by its technical characters. The flesh is rich and salmon-red, becoming suddenly pale as the spawning season draws near. Footnote 7: For valuable accounts of the habits of this species the reader is referred to papers by the late Cloudsley Rutter, ichthyologist of the _Albatross_, in the publications of the United States Fish Commission, the _Popular Science Monthly_, and the _Overland Monthly_. [Illustration: FIG. 53.—Quinnat Salmon (female), _Oncorhynchus tschawytscha_ (Walbaum). Columbia River. ] [Illustration: FIG. 54.—King-salmon grilse, _Oncorhynchus tschawytscha_ (Walbaum). (Photograph by Cloudsley Rutter.) ] [Illustration: FIG. 55.—Male Red Salmon in September, _Oncorhynchus nerka_ (Walbaum). Payette Lake, Idaho. ]