The best-known genus, _Osmerus_, includes the smelt, or spirling (éperlan), of Europe, and its relatives, all excellent food-fishes, although quickly spoiling in warm weather. _Osmerus eperlanus_ is the European species; _Osmerus mordax_ of our eastern coast is very much like it, as is also the rainbow-smelt, _Osmerus dentex_ of Japan and Alaska. A larger smelt, _Osmerus albatrossis_, occurs on the coast of Alaska, and a small and feeble one, _Osmerus thaleichthys_, mixed with other small or delicate fishes, is the whitebait of the San Francisco restaurants. The whitebait of the London epicure is made up of the young of herrings and sprats of different species. The still more delicate whitebait of the Hong Kong hotels is the icefish, _Salanx chinensis_. _Retropinna retropinna_, so called from the backward insertion of its dorsal, is the excellent smelt of the rivers of New Zealand. All the other species belong to northern waters. _Mesopus_, the surf-smelt, has a smaller mouth than _Osmerus_ and inhabits the North Pacific. The California species, _Mesopus pretiosus_, of Neah Bay has, according to James G. Swan, "the belly covered with a coating of yellow fat which imparts an oily appearance to the water where the fish has been cleansed or washed and makes them the very perfection of pan-fish." This species spawns in late summer along the surf-line. According to Mr. Swan the water seems to be filled with them. "They come in with the flood-tide, and when a wave breaks upon the beach they crowd up into the very foam, and as the surf recedes many will be seen flapping on the sand and shingle, but invariably returning with the undertow to deeper water." The Quilliute Indians of Washington believe that "the first surf-smelts that appear must not be sold or given away to be taken to another place, nor must they be cut transversely, but split open with a mussel-shell." The surf-smelt is marine, as is also a similar species, _Mesopus japonicus_, in Japan. _Mesopus olidus_, the pond-smelt of Alaska, Kamchatka, and Northern Japan, spawns in fresh-water ponds. [Illustration: FIG. 83.—Eulachon, or Ulchen. _Thaleichthys pretiosus_ Girard. Columbia River. Family _Argentinidæ_. ]