230 "PERFECT-MOUTHED" FISHES 



are carried ; and it is said that, after hatching, the young fry 

 will follow their parent and even return to the brood pouch for 

 shelter should danger threaten. 



The Teostei are divided into numerous genera, families, and 

 species. The most valuable food fishes belong to the Herring, 

 Cod, Salmon, Mackerel, and Flat-fish families. 



The fishes belonging to the great Herring family are never of 

 very large size. They are covered with thin scales without spines, 

 and their fins are spineless too. The head is not clothed with 

 scales, and the snout has no barbels. Near the centre of the back 

 is a small dorsal fin ; there is usually a short ventral fin near the 

 tail, and the pelvic fins are below or a little in front of the dorsal. 

 The mouth is large and furnished with small, weak teeth ; the air- 

 bladder is well developed and of a more or less simple nature, and 

 the colour of the fishes is bluish or greenish on the back, while 

 the sides are silvery and often iridescent. 



The members of this family move about in shoals often containing 

 enormous numbers, swimming in mid-water or near the surface. 

 Their food consists of minute free-swimming creatures which are 

 strained from the water by the gill-rakers, curious sieve-like pro- 

 cesses composed of a series of comb-like teeth on the gill-bars. 



The Herring family has a very wide distribution, and is of con- 

 siderable commercial importance, different species ranging through- 

 out the temperate and tropical regions and visiting the coasts in 

 immense shoals at regularly recurring periods, when they are caught 

 in drift, seine, or bag nets. The British species include: the 

 Herring (Clupea harengm) ; the Sprat (C. sprattus) ; the Pilchard 

 or Sardine (C. pilchardus) ; the Shads (C. alosa and C. finta), and 

 the Anchovy (Engraulis encrasicholus). ;' 



The " sardine " is the immature state of the Pilchard, caught 

 chiefly on the west coast of France. " Whitebait " is the fry of 

 both Herrings and Sprats. 



The Cod family (Gadida) contains about 120 different species. 

 They are almost all sea-dwellers frequenting the deeper waters, 

 and are carnivorous and extremely voracious in their habits. 

 They are clothed with small, thin, cycloid scales, and their fins 

 are without spiny rays, but their jaws are very powerful and 

 furnished with strong teeth with which they crush the shells of 

 molluscs and Crustacea which form part of their food ; most mem- 



