734 PISCES-SHAD. 



that the latter should be chilled by the genial warmth of the spring, and 

 warmed by the polar frost. Now, so far is the production offish from being 

 independent of the influence of heat, that, just as one would be led to infer 

 from the slow progress of the solar beams through the element in which 

 they live, they require the whole, or the greater part of our summer, to ma- 

 ture the germs of their countless broods. Nay, it appears that many, if not 

 most of the species, cannot mature their spawn in the depths of the ocean, 

 to which they retire to recruit their strength, but that they come to the 

 shores and shallows, where the heat of the sun can penetrate to the bottom, 

 and be reflected by it, for the purpose of maturing, as well as depositing, 

 their spawn. 



"The herrings come to the shores and estuaries to mature and propagate 

 their spawn, which they do over a greater range of the year than most other 

 fish; continuing the operation to the middle of winter, and retiring into 

 deeper water after that is done. But there is no reason to conclude, that 

 they have much migration in latitude ; or, that they ever move far from 

 those shores which they frequent in the season. The fry too are found on 

 the shores and in the bays and estuaries frequented by their parents ; and 

 they do not go to the deep water till late in the season. They even appear 

 to go farther up the rivers than the old fish, for they may be taken in brack- 

 ish water, with a common trout fly." 



THE SHAD' 



Is taken in many rivers; those of the Severn are most esteemed in England, 

 and are distinguished by the London fishmongers by the French name of 

 alosse. The Thames shad is a very insipid, coarse fish. The Thames 

 shad, when it visits the Severn, is called the twaite, and is held in great 

 disrepute. 



The difference between the two kinds is as follows: — The true shad 

 weighs from four to eight pounds ; the twaite from half a pound to two. 

 The twaite may also be known from a small shad, by having one or more 

 Hack spots on the sides; when it has only one, it is always near the gill. 



The shad of America is a very superior fish, and is abundant in all the 

 northern rivers. Those of the Connecticut are particularly esteemed, and, 

 when salted and barrelled, command a high price. These fish are chiefly 

 taken during the months of April and May. They ascend the rivers for 

 many miles, and formerly large numbers of them were caught in the Con- 

 necticut, at the distance of two hundred miles from its mouth. 



Clupca alosa, Lis. 



