The humpback salmon, or pink salmon (_Oncorhynchus gorbuscha_), is the smallest of the American species, weighing from 3 to 5 pounds. It has usually 15 anal rays, 12 branchiostegals, 28 (13 + 15) gill-rakers, and about 180 pyloric cœca. Its scales are much smaller than in any other salmon, there being 180 to 240 in the lateral line. In color it is bluish above, silvery below, the posterior and upper parts with many round black spots, the caudal fin always having a few large black spots oblong in form. The males in fall are dirty red, and are more extravagantly distorted than in any other of the _Salmonidæ_. The flesh is softer than in the other species; it is pale in color, and, while of fair flavor when fresh, is distinctly inferior when canned. [Illustration: FIG. 56.—Humpback Salmon (female), _Oncorhynchus gorbuscha_ (Walbaum). Cook's Inlet. ] The masu, or yezomasu (_Oncorhynchus masou_), is very similar to the humpback, the scales a little larger, the caudal without black spots, the back usually immaculate. It is one of the smaller salmon, and is fairly abundant in the streams of Hokkaido, the island formerly known as Yezo. [Illustration: FIG 57.—Masu (female), _Oncorhynchus masou_ (Brevoort). Aomori, Japan. ] Of these species the blue-back or red salmon predominates in Frazer River and in most of the small rivers of Alaska, including all those which flow from lakes. The greatest salmon rivers of the world are the Nushegak and Karluk in Alaska, with the Columbia River, Frazer River, and Sacramento River farther south. The red and the silver salmon predominate in Puget Sound, the quinnat in the Columbia and the Sacramento, and the silver salmon in most of the smaller streams along the coast. All the species occur, however, from the Columbia northward; but the blue-back is not found in the Sacramento. Only the quinnat and the dog-salmon have been noticed south of San Francisco. In Japan _keta_ is by far the most abundant species of salmon. It is known as saké, and largely salted and sold in the markets. _Nerka_ is known in Japan only as landlocked in Lake Akan in northern Hokkaido. _Milktschitsch_ is generally common, and with _masou_ is known as masu, or small salmon, as distinguished from the large salmon, or saké. _Tschawytscha_ and _gorbuscha_ are unknown in Japan. _Masou_ has not been found elsewhere.