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. [Illustration: 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. 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. [Illustration: FIG. 42.—Hickory-shad, _Dorosoma cepedianum_ (Le Sueur). Potomac River. ]