290 BRITISH FRESH-WATER FISHES 



the regular inland migration begins. Nearly all the fish caught 

 are disposed of locally, in the Forest of Dean, the flesh being 

 described as similar, but inferior, to that of the herring. Shad 

 occasionally ascend the Tay, the Tweed, and other rivers on the 

 east coast, and when one of them gets into the herring-nets it 

 is recognised as the " queen of the herrings." 



Shad spawn in shallow parts of rivers in May and June, 



descending to the sea again in August. Navigation weirs 



have interfered with its ascent of the Severn, and 



Habits. . ,, i i ,i 



now it is never seen in that river higher than 

 Worcester. It is not a sporting fish in any sense, although 

 occasionally one may be taken by people " whiffing " for 

 mackerel or pollack. In size the shad must be reckoned an 

 important fish, most commonly weighing about 3 lb., but often 

 attaining double that weight. 



The Twait Shad (Clupea finta) 



FINS. 



As in the Allis shad. 



TEETH. 



As in the Allis shad. 



There are no outward marks of distinction between 

 the Twait shad and the Allis shad, save that the former 

 is the smaller fish. Inasmuch as both kinds of shad fre- 

 quent the same rivers at simultaneous seasons, and observe 

 precisely the same habits, it might seem unnecessary to 

 differentiate them as separate species ; but there is one con- 

 stant feature to prove that they are really different fish. In 

 the Allis shad, as mentioned above, the outer branchial arch 

 supports from sixty to eighty very fine and long gill-rakers 

 horny processes present in most Teleostean fish, which 

 serve to protect the delicate organ within from contact with 

 such floating substances as might be drawn in. The Twait 

 shad, on the other hand, has but twenty-one to twenty-seven 

 gill-rakers, which are stout and bony. Its flesh is said to 



