THE HERRING FAMILY 



149 



but the scales arc smaller, the belly spines much stronger, 

 the body deeper behind the head. The gill-rakers long,' 

 thin, and numerous. 



5. The Twait Shad. Distinguished from the Allis Shad 



best by the gill-rakers, which are sharper, thicker, and 

 fewer ; a row of dark spots along the side from the head 

 to a point behind the dorsal fin. 



II. Species in which the snout projects beyond the mouth, so 

 that the latter is beneath the head ; the sides of the gape un- 

 protected when the mouth is open, and the gape itself reaching 

 back far behind the eyes. 



6. The Anchovy. 



Of these six species the pilchard is the most truly marine 

 in its habits, but is nevertheless, at some places, as at St. Ives, 

 taken in very great numbers by the seine; it seldom enters 

 estuaries. The anchovy also is not found in estuaries. Sprat 

 and herring are found in brackish water, especially in the 

 young state, while the shads regularly ascend rivers in order 

 to spawn. 



The eggs of these fishes have certain common peculiarities of 

 structure, but the conditions in which they are placed to undergo 

 their development are extraordinarily various. The spawn of the 

 herring is deposited in the sea or near the mouths of rivers, and 

 is heavy and adhesive, so that it sticks firmly to stones or fixed 

 objects on the sea-bottom. The eggs of the sprat and pilchard 

 on the contrary are of the buoyant kind, and float about 

 separately in the sea like those of cod or flat-fish ; the eggs of 

 the anchovy are also buoyant and marine. The eggs of the 

 shads are shed in fresh or nearly fresh water, and develop at the 

 bottom of rivers, but they are not adhesive, remaining free and 

 separate during development. The peculiarity of structure in 

 which all the eggs resemble one another is that the yolk is com- 

 pound, made-up of a number of separate portions. In the 

 herring these yolk masses are globules of various sizes and the 

 eggs are not very transparent. In the other kinds the yolk 

 masses are not globular, but angular from mutual pressure, and 

 the eggs are quite transparent. 



The hatched larva is very long and slender, and in all cases 



