638 THE LIVING ANIMALS OF THE WORLD 



The Sea-horses have a still more eccentrically modified form, inasmuch as the body is 

 thrown into a series of curves, the head being bent upon the trunk in a manner suggestive 

 of the head and neck of the horse; hence the name of the group. The tail, which lacks the 

 membranous portion, or fin, can be spirally coiled, and is used as an organ of prehension, 

 and on this account is unique amongst fishes. Gripping the stems of seaweeds with this tail, 

 and swaying the body to and fro among the vegetation, the fish is rendered comparatively incon- 

 spicuous, the lines of the body being broken up b\- numercjus more or less filamentous pro- 

 cesses, which in one species, the P""ljCUS-LlKE Sea-HoRSE, beccmie excessively developed, forming 

 long, frond-like blades. These, streaming in the water, both hy their shape and coloration 

 render the resemblance to the vegetable growths in which the animal hides so perfect that 

 detection is almost impossible. Thus they furnish one of the most remarkable examples of 

 adaptation to the enx'ironment amongst li\'ing animals. The males of most sea-horses, like the 

 pipe-fishes, carr}- the eggs and young in a pouch on the abdomen, but in the species just 

 mentioned the eggs are embedded in the soft skin on the under surface of the tail. 



Sea-horses swim \\ith the body more or less vertical, the motive power being supplied 

 b\- rapid vibration of the back-fin. Both pipe-fishes and sea-horses occur in British seas, the 

 first being the more common. 



Phct^ by H. y. Lelimanvl 



COFFER-FISHES 



Cojftr-fis/ies hai'e the body encased in a hard ihcil of closely fitting plates, leai'hi^ only the tail and fins free to moi'e 



The C( >Mii-GiLLEi) Fishes, to which we come next, arc divided into two families, whose 

 members are as remarkable for their extraordinary shape as are the tuft-gilled forms just 

 discussed. The abnormal shapes which mark out certain fishes so conspicuously from the more 

 normal and typical forms are generally regarded as adaptations, serving to ensure concealment, 

 to ward oft" attack, or to effect the capture of prey otherwise unattainable. Instances illustrating 

 all three of these ends are furnished by these two groups of the tuft- and comb-gilled fishes. 



The FlEE-ElSHES and Cdffer-FISHES, which form the first of the two families, present 

 considerable variation in shape as well as in the covering of the bod)', which may be naked, 

 covered with rough scales or bony spines, or invested in a complete bony cuirass. 



The file-fishes are represented by numerous species, the tj'pical one being known also as 

 the TI'11G(;ei-i-I'ISH, on account of an -armature of spines on the top of the back. These spines 

 are three in number; the first is very strong, roughened like a file — hence the name File- 

 fish — and hollowed out behind to receive the second much smaller spine, which has a 

 projection in front at its base, fitting into a notch in the first. Thus these two spines can 

 onlv be raised or depressed simultaneously, and the first cannot be forced down unless the 

 second has been previously depressed. These fishes have very powerful teeth, to break oft' 

 pieces of coral, which form a large part of their diet. They also destroy a large number of 

 shell-fish, and work great destruction amongst pearl-oysters. Frequently these fishes, when 

 eaten, prove highly poisonous, from having fed on poisonous corals, jelly-fish, or decomposing 

 substances. 



