Page:Popular Science Monthly Volume 12.djvu/317

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curious of the class, as well by reason of the protuberance and the sharp, recurved horns of the head, and the compressed and unequal spines of the back, as on account of the broad, yellow, green, and brown zebraizations which adorn the body. The jaws sometimes are armed with minute teeth like the nap of velvet, as in the archer-fish; sometimes these teeth are superseded by fine, compact, silky filaments, performing the same functions as the barbs of the whale—they serve to strain the water and to retain the little animals on which the fish preys. The fishes of this class are the Chœtodon, with its rich colors; the Holacanthus, which is perhaps the most beautiful member of the family; the Pomacanthus, known to our French colonists as Le Portugais (the Portuguese); and sundry others.

Of the Chœtodons, some have the muzzle long and slender, formed by the bones of the jaw, which are united along nearly their entire length by a membrane, so that the mouth is simply an horizontal slit at the extremity of this cylinder, or elongated cone. The vertical diameter of the body is very great, and the upright fin of the back is high and scaly; the tail is cut square; the profile, which is concave in front of the eyes, rises almost vertically, so that the snout is about one-fourth the depth of the head. These fishes, known under the name of Chelmons, inhabit the Indian Ocean; naturalists distinguish two species, the beaked Chelmon and the long-beaked Chelmon (see the latter in Fig. 1). These species differ from each other not only in length of beak, but also in the arrangement of the colors which adorn them.

PSM V12 D317 Archer fish.jpg
Fig. 1.

In the beaked Chelmon the body is greenish and iridescent; the fins are green, with reflection of azure; a black spot, surrounded by a pearl-white circle, is seen on the dorsal fin, in length about one-third that of the soft rays; five vertical stripes of azure-color, and