In the tropical Pacific occur other valued species, largely belonging to the genus Kowala. The genus Harengula contains small species with very large, firm scales which do not fall when touched, as is generally the case with the sardines. Most common of these is Harengula sardina of the West Indies. Similar species occur in southern Europe and in Japan.
Fig. 40.—Menhaden, Brevoortia tyrannus (Latrobe). Wood's Hole, Mass.
In Opisthonema, the thread-herring, the last dorsal ray is much produced, as in the gizzard-shad and the tarpon. The two species known are abundant, but of little commercial importance. Of greater value are the menhaden, or the moss-bunker, Brevoortia tyrannus, inhabiting the sandy coasts from New England southward. It is a coarse and bony fish, rarely eaten when adult, although the young in oil makes acceptable sardines. It is used chiefly for oil, the annual yield exceeding in value that of whale-oil. The refuse is used as manure, a purpose for which the fishes are often taken without preparation, being carried directly to the cornfields. From its abundance this species of inferior flesh exceeds in commercial value almost all other American fishes excepting the cod, the herring, and the quinnat salmon.
One of the most complete of fish biographies is that of Dr. G. Brown Goode on the "Natural and Economic History of Menhaden."
Numerous other herring-like forms, usually with compressed bodies, dry and bony flesh, and serrated bellies, abound in the tropics and are largely salted and dried by the Chinese. Among these are Ilisha elongata of the Chinese coast. Related forms occur in Mexico and Brazil.
The round herrings, small herrings which have no serrations on the belly, are referred by Dr. Gill to the family of Dussumieriidæ. These are mostly small tropical fishes used as food or bait. One of these, the Kobini-Iwashi of Japan (Stolephorus japonicus), with a very bright silver band on the side, has considerable commercial importance. Very small herrings of this type in the West Indies constitute the genus Jenkinsia, named for Dr. Oliver P. Jenkins, the first to study seriously the fishes of Hawaii. Other species constitute the widely distributed genera Etrumeus and Dussumieria. Etrumeus sardina is the round herring of the Virginia coast. Etrumeus micropus is the Etrumei-Iwashi of Japan and Hawaii.
Fig. 41.—A fossil Herring, Diplomystus humilis Leidy. (From a specimen obtained at Green River, Wyo.) The scutes along the back lost in the specimen. Family Clupeidæ.
Fossil herring are plentiful and exist in considerable variety, even among the Clupeidæ as at present restricted. Histiothrissa of the Cretaceous seems to be allied to Dussumieria and Stolephorus. Another genus, from the Cretaceous of Palestine, Pseudoberyx (syriacus, etc.), having pectinated scales, should perhaps constitute a distinct subfamily, but the general structure is like that of the herring. More evidently herring-like is Scombroclupea (macrophthalma). The genus Diplomystus, with enlarged scales along the back, is abundantly represented in the Eocene shales of Green River, Wyoming. Species of similar appearance, usually but wrongly referred to the same genus, occur on the coasts of Peru, Chile, and New South Wales. A specimen of Diplomystus humilis from Green River is here figured. Numerous herring, referred to Clupea, but belonging rather to Pomolobus, or other non-Arctic genera, have been described from the Eocene and later rocks.