54G REPORT OF COMMISSIONER OF FISH AND FISHERIES. [22] 



The shape of the body of the herring-is more slender, whilst the sprat 

 is thickset. Corresponding with this the height of body is, in proportion 

 to the length, greater in the sprat than in the herring. And this height 

 is greater in the sprat from the point of the head to the root of the 

 caudal fin. 



The side-length of the head is about the same in both, and is one-fifth 

 of the length of the body. The length of the top of the head from the 

 point of the lower jaw to the point where the scales commence is the 

 same in both. The lower length of the head, from the point of the 

 lower jaw to the hindermost point of the gill-membrane (Fig. II, Kh, 

 and Fig. Ill, A), is greater in the sprat than in the herring. The height 

 of the head is a little greater in the sprat at the end of the upper length 

 of the head, but a little smaller at the joint of the lower jaw. 



The lower jaw of the sprat is shorter than that of the herring. This, 

 and the difference in the height of the head, make the head of the sprat 

 appear more thickset, and the snout more pointed, than that of the 

 herring. When the mouth is closed the point of the lower jaw of the 

 sprat is about as high as the center of the eye, whilst that of the her- 

 ring is higher. 



At the top of the head, between the eyes, the sprat is broader than 

 the herring. 



The bony plates of the gill-coverings or opercles are differently shaped 

 in the two kinds of fish. 



The principal plate (Fig. Ill, 1) of the sprat is broader than that 

 of the herring, and its lower front corner extends lower than in the 

 herring. 



A straight line drawn from the upper root of the pectoral fin towards 

 the lower front corner of the principal i>late (1) of the gill-covering, if 

 extended would, in the herring, go through the eye, and in the sprat, 

 below the eye, towards the point of the upper jaw. 



The upper portion of the gill-membrane (Figs. II and III) below the 

 middle plate (4) of the gill-covering is longer in the sprat than in the 

 herring. In the herring the hinder edge of the gill-membrane and the 

 lower edge of the gill-covering (3) form a distinct angle, whilst in the 

 sprat they almost run in the same direction. 



The ventral fins of the herring are longer and broader than those of 

 the sprat, and have generally 9 rays, whilst those of the sprat have 

 only 7. 



The dorsal fin of the sprat has 17 rays, and is placed farther back 

 than that of the herring, which has 19 rays. In the herring it is placed 

 in front of the center of the whole length of the body, whilst in the sprat 

 it is set back of this point. 



The ventral fins of the herring are found at a considerable distance 

 behind the origin of the dorsal fin, whilst those of the sprat are in front 

 of it. 



