402 AMERICAN FISHES. 
purpose of spawning. In these upward migrations the schools of mature 
fish ascend the rivers either until obstructed by impassable falls or dams, 
or until the volume of water becomes very inconsiderable. Before artificial 
impediments were placed in the rivers, the limit of this movement was the 
natural and insurmountable falls to be found at the head of almost all of 
our principal streams. For example, in the Savannah River the Shad used 
to ascend to the Falls of Tallula, at the very source of the river in the 
northern part of Georgia. In the Potomac they ascend as high as the 
Great Falls. In the Susquehanna River, in which there exist no natural 
obstructions, their migration extended up into the State of New York, a 
distance of several hundred miles above the present limit. On the Hudson 
River they ascended to Glens Falls. On the Connecticut at one time they 
went as high as Bellows Falls, but recent obstructions in this river have 
materially reduced the extent of their range. 
The age at which the Shad reaches maturity and becomes capable of 
reproducing is not definitely determined; it is generally held by fish 
culturists, however, that the female Shad attains this condition when three 
or four years old. The favorite spawning grounds, or ‘‘Shad Wallows,’’ 
as they are termed by the fishermen, are on the sandy flats which border 
the streams, and the sand-bars which are found at intervals higher up the 
river. When the fish have reached suitable spawning grounds and are 
ready to cast their eggs, they move up to the flats seemingly in pairs. The 
time of this movement is usually between sundown and 11 p. m. When 
in the act of coition they swim close together and near the surface, 
their back fins projecting above the water. The rapid, vigorous, spas- 
modic movements which accompany this operation produce a splashing in 
the water which can be plainly heard from the shore, ard which the fisher- 
men characterize as ‘‘ washing.’’ 
The number of eggs in the ovary of a Shad, as in all other fish, bears a 
certain relation to the size and weight of the fish. As the result.of ex- 
perience in the artificial propagation of the Shad we conclude that a ripe 
roe Shad weighing four or five pounds contains from 20,000 to 40,000 
eggs, the average number being about 25,000. A much larger number, 
however, has been obtained from some individuals. In the season of 
1881 we obtained from a single Shad, weighing about six pounds, over 
60,000 impregnated eggs; again, in 1880; on the Potomac River, the 
yield of eggs from a single Shad was over 100,000. These were full-sized, 
