Several American fossil herring-like fishes, of the genus Leptosomus, as Leptosomus percrassus, are found in the Cretaceous of South Dakota.
Fossil species doubtfully referred to Dorosoma, but perhaps allied rather to the thread-herring (Opisthonema), being herrings with a prolonged dorsal ray, are recorded from the early Tertiary of Europe. Among these is Opisthonema doljeanum from Austria.
Fig. 42.—Hickory-shad, Dorosoma cepedianum (Le Sueur). Potomac River.
The Dorosomatidæ.—The gizzard-shad, Dorosomatidæ, are closely related to the Clupeidæ, differing in the small contracted toothless mouth and reduced maxillary. The species are deep-bodied, shad-like fishes of the rivers and estuaries of eastern America and eastern Asia. They feed on mud, and the stomach is thickened and muscular like that of a fowl. As the stomach has the size and form of a hickory-nut, the common American species is often called hickory-shad. The gizzard-shad are all very poor food-fish, bony and little valued, the flesh full of small bones. The belly is always serrated. In three of the four genera of Dorosomatidæ the last dorsal ray is much produced and whip-like. The long and slender gill-rakers serve as strainers for the mud in which these fishes find their vegetable and animal food. Dorosoma cepedianum, the common hickory-shad or gizzard-shad, is found in brackish river-mouths and ponds from Long Island to Texas, and throughout the Mississippi Valley in all the large rivers. Through the canals it has entered Lake Michigan. The Konoshiro, Clupanodon thrissa, is equally common in China and Japan.
The Engraulididæ.—The anchovies (Engraulididæ) are dwarf herrings with the snout projecting beyond the very wide mouth. They are small in size and weak in muscle, found in all warm seas, and making a large part of the food of the larger fish. The genus Engraulis includes the anchovy of Europe, Engraulis encrasicholus, with similar species in California, Chile, Japan, and Australia. In this genus the vertebræ are numerous, the bones feeble, and the flesh tender and oily. The species of Engraulis are preserved in oil, often with spices, or are made into fish-paste, which is valued as a relish. The genus Anchovia replaces Engraulis in the tropics. The vertebræ are fewer, the bones firm and stiff, and the flesh generally dry. Except as food for larger fish, these have little value, although existing in immense schools. Most of the species have a bright silvery band along the side. The most familiar of the very numerous species is the silver anchovy, Anchovia browni, which abounds in sandy bays from Cape Cod to Brazil. Several other genera occur farther southward, as well as in Asia, but Engraulis only is found in Europe. Fossil anchovies called Engraulis are recorded from the Tertiary of Europe.
Fig. 43.—A Silver Anchovy, Anchovia perthecata (Goode & Bean). Tampa.
Fig. 44.—Notogoneus osculus Cope. Green River Eocene. Family Gonorhynchidæ.