=The Dolphins: Coryphænidæ.=—The dolphins, or dorados (_Coryphænidæ_), are large, swift sea-fishes, with elongate, compressed bodies, elevated heads, sharp like the cut-water of a boat, and with the caudal fin very strong. The long dorsal fin, elevated like a crest on the head, is without spines. The high forehead characteristic of the dolphin is developed only in the adult male. The flesh of the dolphin is valued as food. Its colors, golden-blue with deep-blue spots, fade rapidly at death, though the extent of this change has been much exaggerated. Similar changes of color occur at death in most bright-colored fishes, especially in those with thin scales. The common dolphin, or dorado (_Coryphæna hippurus_), is found in all warm seas swimming near the surface, as usual in predatory fishes, and reaches a length of about six feet. The small dolphin, _Coryphæna equisetis_, rarely exceeds 2½ feet, and is much more rare than the preceding, from which the smaller number of dorsal rays (53 instead of 60) best distinguishes it. Young dolphins of both species are elongate in form, the crest of the head not elevated, the physiognomy thus appearing very different from that of the adult. _Goniognathus coryphænoides_ is an extinct dolphin of the Eocene. [Illustration: FIG. 222.—Dolphin or Dorado, _Coryphæna hippurus_ Linnæus. New York. ] The name dolphin, belonging properly to a group of small whales or porpoises, the genus _Delphinus_, has been unfortunately used in connection with this very different animal, which bears no resemblance to the mammal of the same name. Other mackerel-like families not closely related to these occur in the warm seas. The _Leiognathidæ_ are small, silvery fishes of the East Indies. _Leiognathus argentatus_ (_Equula_) is very common in the bays of Japan, a small silvery fish of moderate value as food. _Gazza minuta_, similar, with strong teeth, abounds farther south. _Leiognathus fasciatum_ is common in Polynesia. A fossil species called _Parequula albyi_ occurs in the Miocene of Licata. The _Kurtidæ_ are small, short-bodied fishes of the Indian seas, with some of the ribs immovably fixed between rings formed by the ossified cover of the air-bladder and with the hypocoracoid obsolete. _Kurtus indicus_ is the principal species. =The Menidæ.=—Near the _Kurtidæ_ we may perhaps place the family of _Menidæ_, of one species, _Mene maculata_, the moonfish of the open seas of the East Indies and Japan. This is a small fish, about a foot long, with the body very closely compressed, the fins low and the belly, through the extension of the pelvic bone, a good deal more prominent than the back. The ventral fins have the usual number of one spine and five soft rays, a character which separates _Mene_ widely from _Lampris_, which in some ways seems allied to it. [Illustration: FIG. 223.—_Mene maculata_ (Bloch & Schneider). Family Menidæ. Japan. ]