168 FISH-CULTURAL ASSOCIATION. 
river temperature are (1) Winter Quarter Shoals for the ocean 
plateau, (2) Wolf-trap Light for Chesapeake Bay, and (3) Wash- 
ington, D. C., for the Potomac River. 
The station at Winter Quarter Shoals is up the coast about 
forty miles north of Cape Charles,and is about eight miles from 
shore. “It iS close to the edge of that cold ‘Arctic’current whien 
wedges itself down between the Gulf Stream and the shore, and, 
bringing with it the temperature of Arctic latitudes, builds a 
wall of minimum temperature beyond which the shad probably 
never pass in their migrations. 
The only records of bay temperature available for the season 
of 1881 were the signal service observations in Norfolk Harbor. 
These records, which give the temperature of Elizabeth river 
rather than the bay, indicate more rapid fluctuations than is pos- 
sible in the general temperature of the bay, and give a daily 
range of temperature several degrees higher than that of the 
bay. 
This correction I have approximately applied in the discus- 
sion of the temperature observations of 1881, in order to bring 
them into harmony with the observations of bay temperature 
for 1882 and 1883, which were made by observers at Wolf-trap 
Light. 
This locality is on the west shore of the bay, half way between: 
the Rappahannock and York rivers, and being well off from 
the shore, little influenced by local variations, the temperatures 
taken here may therefore be taken to represent the general tem- 
perature of the bay waters for corresponding dates. 
The result of the study of the data above indicated are graph- 
ically presented in the three outline maps of the Chesapeake and 
Delaware basins, illustrating the movements of the areas of con- 
genial temperatures under the influence of the seasons, and in 
the chart showing the relations between the temperatures of 
the Potomac river during the fishing seasons of 1881, 1882 and 
1883, and the fluctuations in the shad fisheries of the rivers for 
the same period. 
(The rest of Col. McDonald’s remarks were oral and with re- 
ference to the maps and charts exhibited.) 
