VERTEBRATA 271 



with stripes and dashes of blue. The first ray of the dorsal 

 fin is very long, as long as the body of the fish, and supports 

 a scimitar- shaped membrane, which is mottled yellow 

 and blue. The adult male is very rarely seen inshore. 



The " Flat Fishes " (Pleuronectidce) do not strictly belong 

 to the shore, but as they all spend their early life in our 

 sandy bays reference must be made to them. 



The flat fishes spawn in deep water, as do nearly all our 

 food fishes, and the eggs float and hatch on the sea surface. 

 Winds and tides waft eggs or newly-hatched young to 

 shallow waters, where they go through their metamorphoses, 

 and may be seen in hundreds at, and just beyond, tide 

 margin Avhen there is suitable ground. 



When first a flat fish say the plaice emerges from the 

 egg it is in a larval form, not nearly so far advanced in 

 structure as are the little fishes we have described. 



Then when a similar stage is reached only the expert 

 icthyologist would recognise in them the young of the flat 

 fish, for they are symmetrical in every way, the same as 

 the young of ordinary fishes, and they swim at all depths of 

 water. Then they take to bottom, and lie upon -one side 

 (the plaice, etc., on the right side, the turbot and some 

 others on the left, the position constant in each species). 

 The eye which is on the now under side begins to migrate, 

 the bones of the skull twisting accordingly, until the curi- 

 ously asymmetrical form we are so familiar with is reached. 



Specimens in all stages of change can be found in numbers 

 during the months of May and June, in all our sandy bays, 

 at tide margin and in shallow pools. 



A strange member of the Pleuronectidce may often be 

 met with at low spring tides on rocky shores. This is 

 " Muller's Top Knot " (Rhombus hirtus or Rhombus puncta- 

 tus or Zeugopterus maculatus). 



(There may be reason for a revision of names, but it 

 seems to me that some writers have imagined that they 



