=Pachycormidæ.=—In the family of _Pachycormidæ_ the notochord is persistent, the ethmoids and vomer fused and projecting between the maxillaries to form the prominent snout, the teeth large, the body fusiform, the dorsal short, with slender rays and few fulcra or none, and the scales are thin and rhombic. The numerous species are characteristic of the Triassic, Jurassic, and Cretaceous. In _Sauropsis_ (_longimana_) the body is elongate, and the pectoral fins are large and sickle-shaped. _Euthynotus_ has small fulcra. In _Pachycormus_ (_macropterus_, _esocinus_, etc.) the form is robust and the ventral fins are wanting. In _Hypsycormus_ ventrals are present, and the caudal deeply forked. In the American family of _Protosphyrænidæ_ the jaws are armed with very strong teeth, as in the Barracuda, which, however, the species do not resemble in other respects. _Protosphyræna nitida_, _perniciosa_, and numerous other extinct forms, some of them of large size, were voracious inhabitants of the Cretaceous seas, and are found fossil, especially in North Carolina and Kansas. Numerous species called _Erisichthe_ and _Pelecopterus_ are all referred by Hay to _Protosphyræna_. In this family the scapula and coracoids are ossified, and perhaps the vertebræ also, and, as Dr. Hay has recently suggested, the _Protosphyrænidæ_ may really belong to the _Isospondyli_. In any event, they stand on the border-line between the most fish-like of the Ganoids and the most archaic of the bony fishes. The _Liodesmidæ_ (genus _Liodesmus_) are much like _Amia_, but the notochord is persistent, its sheath without ossification. _Liodesmus gracilis_ and _L. sprattiformis_ occur in the lithographic stones of Bavaria. Woodward places _Liodesmus_ with _Megalurus_ among the _Amiidæ_. =The Bowfins: Amiidæ.=—The _Amiidæ_ have the vertebræ more complete. The dorsal fin is many-rayed and is without distinct fulcra. The diamond-shaped enameled scales disappear, giving place to cycloid scales, which gradually become thin and membranous in structure. A median gular plate is developed between the branchiostegals. The tail is moderately heterocercal, and the head covered with a bony coat of mail. The family of _Amiidæ_ contains a single recent species, _Amia calva_, the only living member of the order _Halecomorphi_. The bowfin, or grindle, is a remarkable fish abounding in the lakes and swamps of the Mississippi Valley, the Great Lake region, and southward to Virginia, where it is known by the imposing but unexplained title of John A. Grindle. In the Great Lakes it is usually called "dogfish," because even the dogs will not eat it, and "lawyer," because, according to Dr. Kirtland, "it will bite at anything and is good for nothing when caught."