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VERTEBRATE ZOOLOGY 



fied spine of the dorsal fin on top of the head looks like a trigger 

 and gives them their name. The File-Fishes or Fool-Fishes (Fig. 92) 

 are still more flatly compressed and the scales are reduced to vesti- 

 gial structures; the small mouth with its protruding teeth and the 

 funny staring expression of the eyes have given them an uncompli- 

 mentary name. The Trunk-Fishes (Fig. 93) are big-headed fishes in- 

 closed in a heavy immovable armor, composed of closely united 

 plates, with a large posterior opening that allows the curious little 

 tail to waggle, and smaller openings for the pectoral, dorsal, and anal 

 fins. Puffers or Globe-Fishes are unarmored forms, shaped, when de- 



FIG. 93. Hawaiian Trunk-Fish, Ostrachion schlemmeri. (Redrawn after Jordan 

 and Evermann.) 



flated, much like Trunk-Fishes, but capable of blowing themselves up 

 with water to several times their normal dimensions, thus making 

 themselves difficult to swallow. If taken out of water these strange 

 little fellows suck in air till they are of a drum-like tightness. Some of 

 the Globe-Fishes are said to be extremely poisonous. The Porcupine- 

 Fishes are shaped much like the Puffers in a deflated or partly de- 

 flated condition, some being much rounder than others; but they are 

 covered with a heavy spiky armor that has suggested their name. 

 They also have the reputation of being decidedly poisonous. The 

 Head-Fishes or Sun-Fishes (Fig. 94) represent the climax of relative 

 increase of head over body, a character exhibited by the whole group; 

 they are little more than animated fish heads. The body is so abbre- 

 viated that the dorsal and anal fins appear to be attached to the upper 

 and lower parts of the head. They inhabit the tropical and sub- tropi- 

 cal seas, living a sluggish, floating life that is almost sedentary. Large 



