456 ZOOLOGY. 
eight or nine million of eggs are annually deposited by each 
female. (Blake.) The eggs laid by the cod rise to the sur- 
face of the water, on which they float. The young fish 
hatch on the New England coast in twenty days after they 
areextruded. Several millions of cod were artificially hatched 
at Gloucester, Mass., in the winter of 1878-9, by the United 
States Fish Commission; it has thus been demonstrated 
that this fish can be artificially propagated. 
The cod is the most important of all the food-fishes, 
whether we consider the number taken and the amount of 
capital involved in the cod-fishery. It abounds most on 
the Grand Banks of Newfoundland. The breeding habits 
of the haddock, hake and pollock are probably like those of 
the cod. 
Fierasfer is a small eel-like fish, with a long, thin tail. It 
is typical of a peculiar family, and is noteworthy from being 
a ‘‘commensal” or boarder in the digestive canal of Holo- 
thurians, etc. /. acus Brinn. lives in Holuthurians, and 
another species in a star-fish (Culcita). The Brotulide are 
fishes allied to the cod, but constituting a distinct family. 
Most of them are salt-water species, but allied forms (Lueci- 
fuga subterraneus and Stygicola dentata) live in subterra~ 
nean waters in Cuba. 
At the head of Teleocephali stand the flounders, halibut 
and soles, which are an extremely modified type of the order. 
In these fishes the body is very unsymmetrical, the fish vir- 
tually swimming on one side, the eyes being on the upper 
side of the head. The upper side is colored dark, due as in 
other fishes to pigment-cells ; the lower side is colorless, the 
pigment-cells being undeveloped. When first hatched the 
body of the flounder is symmetrical, and in form is some- 
what cylindrical, like the young of other fishes, swimming 
vertically as they do, and with pigment-cells on the under- 
side of the body. Steenstrup first showed by a series of 
museum specimens that the flounder was not born with the 
eyes on the same side of the head, but that one eye gradually 
passed from the blind to the colored side. Mr. A. Agassiz 
has studied the process, and finds that the transfer of the eye 
from the blind side to the colored side occurs very early ip 
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