THE HERRING FAMILY. 415 



forwards, the ear-capsules are large and swollen, giving the 

 back of the head a bulbous appearance, the pectoral fins project 

 outwards and the median fin is absent from the front part of 

 the body. The specimen figured was nearly 9 mm. in length, 

 and had not yet developed its black pigment to any extent. 

 Considerable variations in this respect are to be observed. In 

 comparing the young herring at this stage with the preceding, 

 we are struck with the great elongation of the body and the 

 conspicuous notochord. This organ, in fact, appears to con- 

 stitute the greater part of the bulk of the body, the muscles 

 and alimentary canal ensheathing it as a thin layer. The total 

 length of the body may be as much as 23^ times the greatest 

 breadth. 



The neighbourhood of the sea-bottom is now forsaken and 

 the post-larval herrings seek the higher regions, moving up 

 through the mid- water, in which they may be caught throughout 

 April by means of the tow-nets. By the middle of the month 

 they reach an average length about -^ inch or more (12 — 1-5 mm.) 

 and present the appearance indicated in Plate XIX, fig. 4. The 

 body has 'filled out,' and the breadth and depth of the little 

 fish bear a much greater proportion to the length than was the 

 case heretofore. 



The continuous embryonic fin has disappeared, leaving a 

 permanent dorsal fin, some way back towards the tail. There 

 is still, nevertheless, a trace of the median fin on the ventral 

 surface, between the tail and the vent, in the position at which 

 the permanent anal fin will arise later, and along the abdominal 

 surface. The gills with their supporting arches and the jaws 

 have undergone important changes tending towards the adult 

 condition. The characteristic pigmentation already described 

 is now very marked, with the addition of a few black spots 

 dusted over the tail-fin. Little change takes place till the end 

 of April, when an average length of about 16 mm. is reached. 



By about the end of June the average-sized young herrings 

 have reached a length of about 25 mm. (or one inch) and after 

 a short sojourn near the surface commence their migration 

 towards the shore, where at a length of 26 to 28 mm. these 

 little herrings may be found in great numbers. The general 



