_Argyrosomus artedi sisco._ Cisco. Head 4 to 5; depth 4 to 4-1/2; eye 4 to 5; D. 10; A. 12; scales 8-65 to 80-8; body long, slender and somewhat compressed; head long, pointed and compressed; mouth large, lower jaw somewhat projecting, maxillary reaching to pupil; mandible 2-1/3 in head; dorsal fin high, its rays rapidly shortened; caudal fin forked. THE ROCKY MOUNTAIN WHITEFISH (_Coregonus williamsoni_) This fine fish was first described from the Des Chutes River in Oregon by Dr. Charles Girard in 1856, who described most of the fishes collected during the Pacific Railroad Survey, and named the one under consideration in honor of Lieutenant R.S. Williamson, who had charge of one of the divisions of the Survey. Its general form is not unlike that of the grayling, which has led to the absurd opinion, held by some, that the grayling is a hybrid, or cross, between this whitefish and the red-throat trout, its body being rather long, nearly elliptical in outline, and somewhat compressed. It is found in the clear streams on both slopes of the Rocky Mountains, and on both sides of the Cascade Range. In the tributaries of the Missouri River in Montana it differs slightly from the typical form, and is known as the variety _cis-montanus_. It is bluish or greenish on the back, sides silvery, belly white. All of the fins are tipped with black; caudal and adipose fins are steel-blue. I know this fish only from the streams of Montana, where it coexists with the red-throat trout and grayling. It spawns in the fall. It feeds on insects and their larvæ, small crustaceans, and the eggs of other fishes. It grows to about a foot in length, usually, and to a pound in weight, though I have taken much larger specimens. It is a very fair food-fish,--as good, I think, as the red-throat trout, as its flesh is firmer and flaky, and devoid of any muddy or musky flavor. It rises to the artificial fly as readily as the trout or grayling, and to the same flies, though a little more partial to small, dark, or grayish ones, as black, brown, and gray hackles, black gnat, oriole, gray drake, etc. When the streams are higher and not so clear, lighter-colored flies are useful, as professor, coachman, Henshall, miller, etc. Light trout fly-rods and tackle are used both for fly and bait-fishing by Rocky Mountain anglers,--the bait, when used, being the larva of the caddis-fly, and known as "rockworm." Grasshoppers are employed in the late summer and fall. Fly-fishing, however, is the most successful method.