THE FAMILY OF THE SCADS, OR HORSE- 

 MACKERELS 



This is a large family of fishes belonging to tropical and 

 temperate seas, and more abundant in the tropics. The fishes 

 included in it show considerable differences from one another, 

 and it is not easy to mention peculiarities which are common to 

 them all. The body is always more or less narrow from side to 

 side, sometimes thin and of great vertical height ; the eyes are 

 on the sides of the head. The spiny front dorsal fin is shorter 

 at the base than the second, and in many species reduced to 

 short separate spines. The lateral line is in some armed with 

 bony plates. There are sometimes separate finlets behind the 

 dorsal and ventral fins as in the mackerel. 



The only fish of this family which is common in British seas 

 is the scad or common horse-mackerel, but the pilot-fish and 

 others have been taken occasionally on our coasts. 



The eggs are not well known, but are probably buo}'ant in 

 the majority of species, if not in all. One species is the skip- 

 jack or blue-fish of the coasts of the United States, and the 

 eggs believed to belong to this fish have a layer of yolk 

 segments and a single oil globule like those of the red mullet. 



The Scad, or Horse-Mackerel. 



Distinguishing CJiaractcrs. — This fish has a front dorsal fin of 

 eight spines, a long soft second dorsal and ventral ; there are 

 two spines in front of and separate from the ventral. The most 

 marked peculiarity is the lateral line, armed throughout its 

 length with plate-like bony scales, which towards the hinder end 

 of the fish are keeled. The scales present on the head and rest 

 of the body are very small. The colour is a dark bluish on 



