On very dark nights, this Globe-fish is sometimes seen swimming in the soft light which emanates from its body, the rays rendered undulating by the rippling of the water which it traverses, so as to resemble the trembling light of the moon half-veiled in misty vapors. When many of these Fishes rove about together, mingling their silvery trains, the scene suggests the idea of dancing stars. The Moon-fish is common in the Mediterranean, and sometimes reaches the markets of Europe. It is about thirty inches in length. THE DIODONS. [Illustration: DIODON.] The curious Diodons differ from the Globe-fish in the form of their bony jaws, each forming only one piece. They differ also in their spines, which are much larger than those of the Globe-fish. These Fishes may be said to be the Hedgehogs and Porcupines of the sea. Like the Globe-fish, they can erect their spines and inflate their bodies. THE COFFERS. The Coffers or Ostracions, are without scales, but are covered with regular bony compartments which are so jointed to one another that the body seems to be enclosed in a kind of box or long coffer, which only reveals the fins and a portion of the tail. The body is usually of a triangular shape, although some species are quadrangular; but no matter what the form, this queer bony box gives the Fish an odd appearance, making it distinct from all others. These singular Fishes are found in the Indian Ocean and in the American seas. They are of moderate size, and of little value as food for mankind. THE FILE-FISH. These have a compressed body, and the jaws are furnished with eight teeth arranged in a single row on each jaw. The mouth is small and the body is enveloped in very hard scales. The File-fish or Balistes are inhabitants of tropical seas, with one exception. They are brilliantly colored, and as they herd together in great numbers they form curious combinations of rare coloring in the equatorial seas. THE PIPE-FISH AND SEA-HORSES. [Illustration: PIPE FISH.] The second division of the bony Fishes is quite small, including only the Pipe-fish and the Sea-horses. These are distinguished by having the gills divided into small round tufts and arranged in pairs—a structure that is peculiar and different from that of any other Fishes. These gills are enclosed under a large cover, which leaves only a small hole for the escape of water which has served the purposes of respiration. The Pipe-fishes belonging to this family possess a very strange organic peculiarity. Their bodies are long, slender, and slightly tapering, covered with plates set lengthwise; and the skin in swelling forms a pouch near the tail into which the eggs glide to be hatched, and which is afterwards a shelter for the young.