Fig. 351.—Spotted Trunkfish, Lactophrys bicaudalis (Linnæus). Cozumel Island, Yucatan.
Fig. 352.—Spotted Trunkfish (face view), Lactophrys bicaudalis (Linnæus).
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.
Fig. 354.—Hornless Trunkfish, Lactophrys trigonus (Linnæus). Tortugas, Fla.
The Gymnodontes.—The group of Gymnodontes, having the teeth united in a turtle-like beak, carry still further the degeneration of scales and fins. There is no trace of spinous dorsal, or ventral. The scales are reduced to thorns or prickles, or are lost altogether. All the species have the habit of inflating themselves with air when disturbed, thus floating, belly upward, on the surface of the water. Very few, and these only northern species, are used as food, the flesh of the tropical forms being generally poisonous, and that often in a higher degree than any other fishes whatever.
