Fish Cultural Association. 
alternative—that of the possibility of sojourn in the warm 
strata of the open ocean. In plate I. is given a diagram 
section of the North Atlantic Ocean between New York and 
Bermuda, showing the soundings and isothermal lines obtained 
in H. M.S. “Challenger,” Apriljeqito, May 8, 1873... Theyverme 
cal scale is necessarily enormously exaggerated, but the dia- 
gram shows the presence of strata under the Gulf Stream and 
between it and the American coast, the temperature of which 
exactly meets the requirements of the menhaden. At a depth 
of 50 to 100 fathoms there is a shoreward extension of the 
warm stratum of 50 deg. to 55 deg., which extends inward 
120 miles, There are no means) of determining the jconme- 
sponding isothermal lines on the coast of North Carolina, but 
an extension of much less degree would approach very near 
the shore in that region. The diagram represents the condi- 
tion of the sea temperatures near New York at the very pe- 
riod when the menhaden are approaching the coast in April, 
and a similar relation not improbable exists in November at 
the time of their departure. The schools of fish, swimming 
out to sea when the shore waters become too cold for them, 
and driven below the surface by the winds of November, 
would naturally strike these temperate strata, and being kept 
from descending deeper by the uniform coldness of the waters 
below, as well as by the increasing pressure, and their efforts 
to approach the shore being also opposed by a temperature 
barrier, they would remain in the temperate strata until they 
were enabled by the warmth of spring to regain their feeding- 
grounds near the shores. 
No authorities can be quoted in support of this hypothesis. 
but in the case of the menhaden, at least, it appears to explain 
more of the difficult questions in relation to periodical move- 
ments than that of hybernation or that of extended migration, 
