In Stephanolepis spilosomus the caudal fin is of a brilliant scarlet color, contrasting with the usual dull colors of these fishes. In Oxymonacanthus longirostris the body is blue with orange checker-like spots and the snout is produced in a long tube. About the islands of Polynesia, filefishes are relatively few, but some of them are very curious in form or color.
Fig. 348.—Common File fish, Stephanolepis hispidus (Linnæus). Virginia.
The Spinacanthidæ.—In the extinct family Spinacanthidæ the body is elongate, high in front and tapering behind. The first dorsal has six or seven spines, and there are rough spines in the pectoral. The teeth are bluntly conical. Spinacanthus blennioides and S. imperalis are found in the Eocene of Monte Bolca. These are probably the nearest to the original ancestor among known scleroderms.
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.
Fig. 349.—Horned Trunkfish, Cowfish, or Cuckold, Lactophrys tricornis (Linnæus). Charleston, S. C.
Fig. 350.—Horned Trunkfish, Ostracion cornutum (Linnæus). East Indies. (After Bleeker.)
