MACKERELS. 165 



(Aplysia) it causes violent diarrhoea when eaten. Odax (700) is 

 a southern genus, occurring on the coasts of Australia and New 

 Zealand ; the edges of the jaws are sharp and the individual 

 teeth composing them cannot be distinguished. Coridodax 

 pullus (701) is the Kelp-fish or Butter-fish of New Zealand; it 

 lives on the small organisms growing on sea-weed, and is largely 

 used as food. 



Scombriformes (Mackerels) . 



The Scombriform fishes, including the Mackerels, Horse- 

 mackerels, Sword-fishes and their allies, are closely connected 

 with the Perciformes; they are carnivorous and marine and many 

 are of wide distribution. The spinous dorsal fin, if distinct, is 

 supported by short or feeble slender spines. The pelvic fins 

 are thoracic in position, with not more than five soft rays in 

 addition to the spine ; rarely without the spine but with more 

 than five jointed rays. The stalk of the tail is much constricted ; 

 the rays of the caudal fin are usually numerous and strongly 

 forked at the base, embracing a considerable portion of the 

 expanded hypural bones. The scales are usually very small or 

 absent. 



The first family, the Scombrida?, includes fishes like the 

 Mackerel (704), Bonito (709), and Tunny (707), with fusiform 

 body, not laterally compressed, with pectoral fins set rather high 

 up the sides of the body, with a distinct lateral line, with wide 

 gape and conical teeth. The premaxillary bones are large and 

 not protractile. There are no free spines in the dorsal and anal 

 fins ; the soft dorsal fin, the hinder part of which is in most cases 

 broken up into finlets, is longer than the spinous portion ; the 

 hind part of the anal fin may, like the dorsal, be in the form of 

 separate finlets. The Scombrid fishes are abundant in all the 

 seas of the tropical and temperate zones ; they include some of the 

 swiftest inhabitants of the sea, and not only are they extremely 

 active, but they have great powers of endurance. Their muscles 

 are of a redder colour than those of most fishes and more resemble 

 those of warm-blooded animals. They spawn in the open sea. 



