=The Trunkfishes: Ostraciidæ.=—The group _Ostracodermi_ contains the single family of _Ostraciidæ_, the trunkfishes or cuckolds. In this group, the body is enveloped in a bony box, made of six-sided scutes connected by sutures, leaving only the jaws, fins and tail free. The spinous dorsal fin is wholly wanting. There are no ventral fins, and the outer fins are short and small. The trunkfishes live in shallow water in the tropical seas. They are slow of motion, though often brightly colored. [Illustration: FIG. 349.—Horned Trunkfish, Cowfish, or Cuckold, _Lactophrys tricornis_ (Linnæus). Charleston, S. C. ] [Illustration: FIG. 350.—Horned Trunkfish, _Ostracion cornutum_ (Linnæus). East Indies. (After Bleeker.) ] [Illustration: FIG. 351.—Spotted Trunkfish, _Lactophrys bicaudalis_ (Linnæus). Cozumel Island, Yucatan. ] [Illustration: FIG. 352.—Spotted Trunkfish (face view), _Lactophrys bicaudalis_ (Linnæus). ] [Illustration: FIG. 353.—Spineless Trunkfish, _Lactophrys triqueter_ (Linnæus). Tortugas. ] Against most of their enemies they are protected by the bony case. The species range from four inches to a foot in length, so far as known. They are not poisonous, and are often baked in the shell. Three genera are recognized: _Lactophrys_ with the _carapace_, three-angled; _Ostracion_ with four angles; and _Aracana_, resembling _Ostracion_, but with the carapace not closed behind the anal fin. In each of these genera there is considerable minor variation due to the presence or absence of spines on the bony shell. In some species, called cuckolds, or cowfishes, long horns are developed over the eye. Others have spines on some other part of the shield and some have no spines at all. No species are found in Europe, and none on the Pacific coast of America. The three-angled species, called _Lactophrys_, are native chiefly to the West Indies, sometimes carried by currents to Guinea, and one is described from Australia. _Lactophrys tricornis_ of the West Indies has long horns over the eye; _Lactophrys trigonus_ has spines on the lower parts only. _Lactophrys triqueter_ is without spines, and the fourth American species, _Lactophrys bicaudalis_, is marked by large black spots. The species of _Ostracion_ radiate from the East Indies. One of them, _Ostracion gibbosum_, has a turret-like spine on the middle of the back, causing the carapace to appear five-angled; _Ostracion diaphanum_ has short horns over the eye, and _Ostracion cornutum_ very long ones; _Ostracion_ _immaculatus_, the common species of Japan, is without spines; _Ostracion sebæ_ of Hawaii and Samoa is deep, rich blue with spots of golden. _Aracana_ is also of East Indian origin; _Aracana aculeata_, with numerous species, is common in Japan. A fossil species of _Ostracion_ (_O. micrurum_) is known from the Eocene of Monte Bolca. [Illustration: FIG. 354.—Hornless Trunkfish, _Lactophrys trigonus_ (Linnæus). Tortugas, Fla. ]