ASYMMETRY OF THE FL0U2fDER. 459 



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 

 are extruded. 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, vv-ith 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. F. acus Briinn. lives in Holuthurians, and 

 another species in a star-fish (Culcita). The Brotulidm are 

 fishes allied to the cod, but constituting a distinct familj^ 

 Most of them are salt-water species, but allied forms [Luci- 

 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 eves 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 

 fiigment-cells being undeveloped. When first hatched the 

 body of the flounder is symmetrical, and ia 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 iu 



