vi COLORATION 173 
thus resembling both in shape and colour the fronds of the sur- 
rounding fucoids and other marine algae amongst which the Fish 
lives. 
Many of the Fishes frequenting the coral reefs of the East 
Indian and Pacific areas, especially those belonging to the Teleo- 
stean families Chaetodontidae and Pomacentridae, have a most 
brilliant and vivid coloration, frequently marked by bands or 
stripes of different tint. So far from rendering these Fishes 
unduly conspicuous, there can be little doubt that, by harmonising 
with the striking and varied colours of the anemone-like coral 
polypes, their coloration is distinctly protective; and it is inter- 
esting to note that similar colour-patterns have been indepen- 
dently reproduced in both families." Even the reef-frequenting 
Flat-Fishes (Pleuronectidae) have the usually sombre upper surface 
ornamented by vivid colours and striking patterns. 
Pelagic Fishes, like the Herring, Mackerel, Flying-Fish (£zo- 
coetus), and many others, often have the belly and sides silvery or 
white, and the back dark green, black, or steely blue. Seen from 
below against the light sky, or viewed from above against the 
background of the dark water, these Fishes would seem to be 
practically invisible to their predatory foes, whether Fishes or 
Birds, or at all events not easily detected. 
Coloration may not only be protective, but also aggressive, by 
helping to conceal the proximity of an animal from its prey; add 
to this some device for deceiving and attracting the prey, and we 
have an example of “alluring” coloration. 
As an example of coloration which is both aggressive and 
alluring, the Angler-Fish or Fishing-Frog (Lophius piscatorius) of 
our own coasts may be quoted. Naturally sluggish and inactive 
in its habits, and often using its muscular pectoral fins for crawl- 
ing about the sea-bottom, the Angler-Fish usually hides itself in 
the sand or amongst sea-weeds, which it closely resembles in 
general colour. Curious branched tag-like processes of soft skin 
fringe the sides of the head and body, and in appearance and 
colour resemble the smaller fronds of the surrounding sea-weed. 
So far the coloration is simply aggressive, and helps to conceal 
the Fish from its prey, but in addition the animal is provided 
with a special device for luring its prey within the reach of 
its capacious and Frog-like mouth. The first three spines 
1 Giinther, Study of Fishes, London, 1880, p. 524. =” Poulton, op. cit. p. 72. 
