174 FISHES CHAP. 
of the dorsal fin are detached from one another and greatly 
elongated, and moreover extend along the middle of the dorsal 
surface of the head. The first, which is the longest, terminates 
in lobes or lappets of skin, and can be freely moved in every 
direction by the muscles inserted into its base. By the agita- 
tion of this lure or bait smaller Fishes, probably mistaking the 
disturbance for the presence of a wriggling worm, are tempted to 
their fate, and soon find themselves engulfed in the enormous 
mouth of the artful angler.‘ In some allied forms (e.g. Ceratias 
bispinosus and Onetrodes eschrichtit)* which live in the abyssal 
darkness of the deep sea, use is made of the attraction which 
light has to aquatic animals, and the fishing-rod spine termi- 
nates in a phosphorescent organ, which is probably used for 
enticing smaller Fishes within the reach of the jaws of these 
singularly modified Angler-Fishes.* 
It is by no means improbable that examples of “ warning ” 
coloration occur amongst Fishes. The brilliant colours of some 
of the Trigger-Fishes (Salistes, Monacanthus), Coffer- Fishes 
(Ostracion), and Globe-Fishes (Zetrodon) are perhaps of this 
nature. They are often associated with the presence of strong 
spines, defensive and often erectile, either in connexion with the 
dorsal fin or on the general surface of the body, and may therefore 
serve the purpose of a danger signal to such predatory foes of 
these Fishes as might otherwise be tempted to attack them— 
to the mutual advantage of the Fishes themselves and their 
would-be enemies. The British Weever-Fish (7Zrachinus) may 
perhaps offer another example of warning coloration.* The Fish 
is armed with poisonous spines on its opercula, and, in addition, 
has a conspicuous black dorsal fin. When the body of the Fish 
is buried in the sand, only its projecting dorsal fin remains to 
indicate its whereabouts to predatory Gurnards, which might 
otherwise mistake the Weever for harmless Fishes of similar 
size and habits. The existence of “recognition ” colours or 
markings peculiar to the species, to enable individuals of the 
same species to recognise one another and to keep together in 
shoals, has not yet been proved. It is probable that the relatively 
1 For another view of the use of the ‘‘lure,” see Cunningham, Marketable 
British Marine Fishes, London, 1896, p. 338. 
2 Giinther, Chall. Reports, Zool. vol. xxii. 1887, p. 50. 
3 Suggested by Liitken ; Giinther, Z.c. 
4 Garstang, quoted by Poulton, op. cit. p. 165. 
FE 
4 
: 
