MARINE FOOD FISHES I15 
end of the tail is crinkled in consequence of being pushed 
through a very small rent in the egg membrane. 
The life history of the plaice has been very thoroughly 
investigated. In the early spring numbers of male and 
female plaice crowd together on the spawning ground. 
Millions of eggs are shed, fertilised, and then rise to float 
during their incubation. Hatching occurs on the average 
about the seventeenth day. When first hatched, the 
little plaice is about one-fifth of an inch in length and 
floats with its yolk sac uppermost. At the end of eight 
days the yolk sac has practically disappeared, and the 
little fish now commences to feed on diatoms. 
At first the growth is very slow, and at the end of a 
month the larval plaice is considerably less than half an 
inch in length, and the eyes are still opposite each other. 
The fish now increases more in depth than in length, 
and this is the first indication that the transformation 
of the symmetrical fish is about to commence. 
The head now gradually rotates and the left eye is 
carried up into a position above the right eye. About 
the fortieth day after hatching the left eye appears on 
the brim of the head, and in another five or six days 
both eyes are in the position which they occupy in the 
adult. The whole transformation takes about six weeks, 
and during this time the plaice has gradually been sink- 
ing to the bottom, and for the last few days lies on its 
left side. The upper surface or right side now shows 
considerable pigmentation, while the lower surface or 
left side is colourless, 
