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 of fish from being 
independent of the influence of heat, that, just as one would be led to infer 
trom 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 
hey 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 ape 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 ¢wazte, and is held 1 in great 
disrepute. 
The difference between the two kinds is as follows:—The true shad 
weighs from four to eight pounds; the t¢waite from half a pound to two. 
The twaite may also be known from a small shad, by having one or more 
tlack 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. 
~~ —-- 
1 Clupea alosa, Lin. 
