MARINE BIOLOGICAL STATION AT PORT ERIN. 



141 



in its body, the muscular system is stronger, and the little 

 fish is able to pursue and capture prey, to eat and digest 

 its food. This at first consists of Diatoms, the spores of 

 sea weeds and other vegetable matters, and a little later 

 on of Copepoda and other minute animals. Post-larval 

 stages taken from our pond in May were found when 

 5 mm. long to be feeding on alga spores, and when 7 mm. 

 and upwards on Copepoda. 



The young post-larval plaice, when it begins to feed, 

 is about one month old, counting eighteen days for 

 hatching and twelve for the absorption of the yolk. 

 Another month is probably required, as a rule, for the 



ust hatched 



Fig. XXXIV., Larval Plaice. (Magnified 15 times.) 



transformation of this bilaterally symmetrical little fish 

 into the completely metamorphosed unsymmetrical flat- 

 fish, with both the eyes on one surface (the right side) of 

 the body, and with a distribution of pigment which causes 

 this upper side to be dark coloured and the lower light. 

 Young plaice, with the metamorphosis completed, have 

 been found only a little over half an inch in length 

 (14 mm.) in June ; but they are usually about an inch 

 in length when they appear in our sandy bays 

 during the summer. In the post-larval stages they lived 

 at the surface, so during the period of their transforma- 

 tion they must be making their way to the bottom, and 

 k 



