344 
SPINE-FINNED GROUP. 
Heniochus. 
a tube-like form, on account of the habits of one of its two Indian species ( Chelmon 
rostratus). Of this fish, which has four dark bands on the head and body, and 
an eye-spot on the soft dorsal fin, J. A. Schlosser wrote many years ago that it 
frequented the shores and sides of the sea and rivers in search of food, and that 
when it detected an insect perched on a plant it swam to within a distance of from 
four to six feet, and then with surprising dexterity ejected out of its tubular mouth 
a single drop of water, which never failed to strike the object aimed at into the 
water, where it was immediately seized by the fish. Some of these fish kept in 
tubs of water were seen to exercise their shooting powers even under these some¬ 
what unfavourable circumstances. Somewhat later a Mr. Mitchell observed the 
same action in some of these fish kept in a pond near Batavia about the year 1828. 
Curiously enough, in spite of these circumstantial statements, this capacity for 
ejecting water was transferred to a short-snouted member of the present family, 
which received its name of Toxotes from this presumed power. Bleeker states, 
however, that when in Batavia he never witnessed this act, which is one the 
mouths of these fishes would appear quite incapable of performing. 
The fish ( Heniochus mctcrolepidotus) numbered 4 in the illus¬ 
tration on p. 342, is a common Indo-Pacific member of a genus 
differing from Chcetodon by the more or less marked elongation of the fourth spine 
of the dorsal fin, which in the figured species assumes the form of a whip-lash. 
Broad dark bands across the body are very characteristic of the genus; and in 
the young the head is armed with numerous horn - like processes, which are 
permanently retained in a species named H. varius. 
The two large fishes shown in the illustration, swimming towards 
Holacantlius. ° . . . 
the lett, belong to a genus distinguished from all the foregoing by the 
presence of a large spine on the hinder-edge of the preopercular bone; the dorsal 
fin having from twelve to fifteen spines. The genus includes some forty species, 
with the same range as the typical representative of the family. The splendidly- 
coloured emperor-fisli ( H. imperator), shown on the right side of the illustration, 
ranges from the east coast of Africa to the Indian and Malayan seas, and has the 
ground-colour of the body a deep blue, upon which are some thirty longitudinal 
golden-yellow stripes. The eye-stripe and a patch above the pectoral fin are black 
edged with yellow ; and the tail-fin is uniformly yellow. This species, which 
attains a length of 15 inches, is extensively used in India for food. Beautiful as it 
is, it is exceeded by the Indo-Malayan zebra-fish ( H'. diacanthus). In this species 
the general colour is yellowish, with from eight to twelve vertical brown-edged 
blue bands; the caudal fin is yellow, and the anal marked with bluish lines running 
parallel to its margin. The genus Scatophagus may be given as an example of a 
group in which the spinous portion of the dorsal fin is devoid of scales and separ¬ 
ated by a deep notch from the soft part, so that there are practically two dorsals. 
The above-mentioned Toxotes, on the other hand, constitutes a group by itself, 
in which there are teeth on the palatines and vomers, and the body is oblong 
and much less deep than in the typical forms, with the undivided and five- 
spined dorsal fin situated in its hinder-half. It is represented by three species, 
ranging from the Red Sea to the seas and estuaries of India, Malayana, and 
Polynesia. 
