216 



BRANCH CHORDATA 



As they go north after spawning vast numbers are caught, whole fleets 

 being engaged in catching them. The mackerel is phosphorescent and the 

 light from these enormous schools is so great that they can be seined at 

 night. They are sold either fresh or salted. One of the largest and swift- 

 est of the mackerel tribe is the sword-fish, in which the upper jaw is de- 

 veloped into a long, bony, sword-like projection (see p. 205). This forms a 

 strong weapon, as the fish dashes into schools of fishes, cutting and slashing 

 and devouring them. It has been known to pierce the wooden and copper 

 bottoms of vessels. It does not breed in North America. The young are 

 not like the adult. 



Fig. 179. — Small-mouthed black bass (Micrup'tcrus dolomieu). (Bull. 

 U. S. F. C, 1900.) 



The sticklebacks are found in both North America and Europe. They 

 derive their name from their formidable dorsal spines. They are small 

 marine or fresh- water fishes. 



Sub-order Pharyngog'nathi includes the Wrasses and "flying- 

 fishes." The pectoral fins of flying-fishes (Fig. 180) are large, 

 and serve as parachutes when the fishes leap from the water. 



Sub-order Plectog'nathi. — To this group belong the file-fishes, 

 which are often protected by plates or spines, and in shape are 

 very deep and thin. They are common from Cape Cod to Cuba. 



Here also belong the trunk-fishes, which are enclosed in a 

 "box" made up of bony plates or scales, the tail, mouth, and fins 

 being movable. 



The porcupine fishes are covered with sharp spines. The 

 Gymnodon'ta or "swell-fishes" can inflate their bodies into spheric 

 sacs. Their flesh is poisonous. 



Sub-order Lophobran'chii. — These fishes are covered with 

 rings of large plates. They have club-shaped tufted gills, no 



