332 FISHES OF THE FIRTH OF FORTH. 



good deal upon the quality of the water ; if it is clear, they 

 ascend early in spring, but if there happens to be a flood, 

 they wait till the waters are restored to their former purity ; 

 and if they meet with a flood in their progress upwards, they 

 immediately return and keep below Gloucester." In the 

 Thames this fish is seldom met with ; and seems to be of 

 equally rare occurrence in the Firth of Forth. Two speci- 

 mens only have fallen under my notice, one of which was 

 taken in the salmon nets in the month of June at Mussel- 

 burgh, and the other was captured in a net along with her- 

 rings, at the mouth of the Firth, in the early part of Janu- 

 ary. It is frequently reported that herrings of large size, 

 measuring from twenty to twenty-four inches in length, are 

 occasionally taken off the Dunbar and Berwickshire coasts, 

 and which the fishermen name the Queen Herrings, but it 

 is probable that the fish they allude to is the Allice Shad. 

 Mr Yarrell states, that " both species of shads have great 

 resemblance, except in size, to the herrings, and have been 

 frequently called the mother of herrings. The large herrings 

 of two feet in length, so called by Anderson and others, 

 and said to occur in the Northern Seas, and among our 

 Northern Islands, are no doubt to be considered as refer- 

 ring to our shads. 1 ' 



The principal food of the shad seems to be small fishes 

 such as sprats, whitebait, and young of the herring. 



The Allice Shad is distinguished from the Twaite Shad, 

 by having a large dusky spot placed behind the upper part 

 of each gill-cover, and by the sides being without spots, and 

 the jaws without teeth. The Twaite shad has from four 

 to seven large dark spots on each side of the body, ar- 

 ranged in a row parallel to the lateral line, and a number 

 of minute teeth on the anterior margin of the upper jaw. 



