56 fish Cultural Association. 
haden is a member. They are provided usually with decid- 
uous scales, and never suffer themselves to come in contact 
with the bottom. If one of the herring or mackerel tribe is 
placed in an aquarium it will be noticed that it keeps itself 
always free from the bottom. Other fishes in the same tank, 
such as the sea-bass, tautog, or king-fish, will be seen to rest 
on the bottom, and even to take refuge under the stones. It 
is extremely improbable that mackerel ever sink into the mud 
of the ocean bottom—still more so in the case of the menha- 
den. 
(3.) It accounts better than the other theories for the early 
appearance of the fish in the spring. Admitting a possibility 
of a winter’s sojourn in the mud, we are met by a difficulty 
when we try to account for the prompt appearance of the 
fishes in the spring. The deeper strata of the ocean are now 
known to preserve throughout the year the uniform tempera- 
ture of 28.4 to 35 deg. The fish, once mummified in the depths 
of the ocean, would remain so for ever unless they are 
admitted to possess powers unknown to exist in other animals. 
On the other hand, if we suppose the fish to be swimming 
in the strata of mid-ocean, we know that they are just in the 
position to be susceptible to all the daily variations of temper- 
ature. Following with the advance of the season the inward 
curving of the Gulf Stream, the warm strata below it gradu- 
ally approaches the shore. The schools of fish are thus en- 
abled gradually to draw nearer to the coast line, and when 
the strata of 50 deg. to 55 deg. in temperature touch the coast 
the menhaden are at hand. 
(4.) It explains as well as the hybernation theory, and bet- 
ter than the migration theory, the peculiarity of the different 
schools at different localities along the coast. This was dis- 
cussed on page 51. 
