THE TRIGGER-FISH 



what we usually find in land vertebrates, whose limbs, 

 in their various parts, or in their relation to the trunk, 

 possess, thanks to their ball and socket joints, ample 

 capacity for movement. In this respect the two 

 principal groups of vertebrates are obviously opposed. 

 It is interesting to observe that this opposition is not 

 absolute, for certain fishes, like the trigger-fish, possess 

 in one of their fins an articulated mechanism. The 

 trigger-fish is not the only example. The great fresh- 

 water cat-fishes of subtropical regions, several of 

 which are to be classed among walking fishes, have 

 similar arrangements for their thick rays with movable 

 points. Indeed, they are occasionally still more per- 

 fected, and they sometimes have articulations like a 

 sort of bayonet fitting. 



But all this, in spite of its interest, is only a detail. 

 The main feature of the trigger-fish is its cuirass. In 

 this respect it is distinguished from the majority of 

 other fishes, which have nothing like it, and can show 

 as a covering for their bodies nothing more than a 

 thin flexible garment of scales. But the trigger-fish 

 has rivals. The sea-horse is one, and its cousin, 

 the pipe-fish. The gurnard, a walking fish, is another; 

 its species have protection for their heads in the form 

 of a solid cap which often extends to the neighbouring 

 parts of the trunk. Another fish of the same family, 

 however, surpasses it; its cuirass, still thicker and 

 more complete, bristles with a number of spines 

 which project as if to increase their defensive value. 

 This is the armed or mailed gurnard. 



This species, well named, for its French name, 

 " Malarmat," taken from an old Romance dialect, 

 means " heavily" or " evilly " armed, bears a close 

 relationship to the true gurnard. The little finger- 

 like tentacles formed by the free rays of its 

 pectoral fin are only two in number, unlike the 

 true gurnard, which has three. Like the latter, it 

 lives in muddy flats near the shore, in fairly deep 

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