CH2E'TODON (xalrs, hair, and oboes, a tooth), a genus of Fishes of the section Acanthopterygii and family Squammipennes. It has the following characters :—Body compressed; mouth small, fur nished with several closely-set rows of long slender bristle-like teeth. The scales (which are usually confined to the body) in this genus extend on to the dorsal and anal fins, so that it is difficult to see where the latter commence.
These fishes abound in the seas of hot climates, frequent rocky shores, and are adorned with beautiful colours. Their most common tints appear to be black and yellow, but brilliant metallic blues and greens of various hues are not unfrequent. Many of the species have a vertical black band in which the eye is placed. In some there are several similar vertical rands on the body ; in others the body is spotted or adorned with oblique or longitudinal bands. They have a large air-bladder ; their intestines are long and ample ; and their emca are numerous, long, and slender. Their flesh is good eating.
The species are numerous, and have been divided into several sub genera; those to which the name Chcetodon is now restricted have the body more or less elliptical, the rays of the dorsal fin forming a tolerably uniform curve, the snout more or less produced, and the pre-operculum sometimes furnished with a small tooth.
In some of this section one or more of the soft rays of the dorsal fin are much produced, and form a long filament ; and others are distinguished by their having very few spines to the same fin.
Chatodon ragabundus, a species which inhabits the coasts of Ceylon, has the body of a pale yellow colour, with numerous oblique brownish purple lines; the dorsal fin is blackish, and has 13 spinous rays ; the caudal fin, or tail, is yellow, with two black bands; the anal fin is blackish with a yellow curved longitudinal band ; its margin is also yellow ; a broad black vertical band extends through the eye ; and the part anterior to this band, as low down as the eye, is of a pinkish hue with yellow streaks. Its length is from 6 to 12 inches • the scales on the body are large ; those on the head are rather small: tubular snout with such precision as frequently to disable the little animal, so that it falls into the water and is devoured.
In those parts where C. rostratus abounds it is frequently kept in vessels of water, and affords much entertainment by the dexterity displayed in shooting at flies which are placed on the vessel for the purpose : it generally approaches to within five or six inches before the drop of water is ejected.
The sub-genus Heniochits differs from the true Chetodons in having the anterior spines of the back produced into a long filament, which is sometimes double the length of the body.
Ephippus maybe distinguished by the species having the dorsal fin deeply cleft between the spinons and soft portions. The spiny portion, which is scaleless when not erected, is received into a groove formed by the scales of the back.
Hofocantkus. The species of this sub-genus have a large spine on the angle of the pre-operculum, and most of them have the edge of the same bone serrated : they are found both in the Atlantic and Pacific uceans.
The next subdivision, Pomocanthus, has the body of a more ele vated form, owing to the sudden rising of the anterior margin of the dorsal fin. The only species known are from the American coasts.
In the last subdivision, Platax, the species may be known by the extremely compressed form of the body, the large vertical dorsal fin (which has the anterior spines almost concealed in the membrane), the long ventral fins, and the teeth. Here, in addition to the fine thickly-set teeth, there are some in front which are trenchant, and each of them is divided into three points.
All the species of this section are found in the Indian Ocean. One has been found-in a fossil state at Mount Bolen.
Platax vespertilio will afford an example of this section. It is found off the coast of Ceylon, and is of a yellowish colour ; the dorsal, anal, and ventral fins are brownish, the back is also mottled with the same colour, and a dark band extends downwards through the eye ; the base of the caudal in is dark brown. This species grows to a large size, and is found in rocky situations, but more commonly in deep water.
The next sub-genus, Chel mon (Les Chelmons, Cuv.), is distinguished by the form of the snout, which is much elongated, open at the end only, and formed by a great elongation of the intermaxillary and under jaw bones.
C. rostratus, a species which inhabits the fresh waters of India, is of a silvery hue and has five brownish bands; the posterior part of the dorsal fin is furnished with a black spot encircled with white.
This fish feeds upon insects, and is remarkable for its mode of procuring them. When it observes a fly or any other insect on a weed, or hovering over the water, it ejects a little drop through its The two species of Chtetodons, of which figures are here given, have been selected from Mr. J. W. Bennett's Fishes of Ceylon,' a work illustrated by beautiful coloured plates.
(Curler, Mgne Animal ; Lac6pede, Histoire Nat urelle, cf.c., des Poissons ; Bloch, Histoire Naturclle, generale et particullere, des Poisson-v.)