SEA-FISHERIES LABORATORY. 175 
pound weight. They are, like the great majority of food 
fish eggs, pelagic or floating on or near to the surface 
during the period of hatching. The flounder on this coast 
proceeds to sea to a depth of 17 fathoms or over to spawn. 
It has been thought by many fishermen that the egg sacs 
of some of the Polychzete worms that are found on the 
shore, of bladder shape and moored by filaments in the 
sand, are the eggs of the flounder; and when the embryo 
worms had attained to the development of the eyes (which 
are red) causing the whole bladder to appear red instead of 
green (the colour before development), it was then taken 
to be plaice spawn because of the plaice having red spots 
on them. 
Spawning takes place in our district from the beginning of 
the year to the end of April. The hatching period is not so 
long as that of the plaice egg, being from 12 days at the 
beginning of the season, to as little as 6 days at the end, 
but regulated in a great measure by the temperature of 
the water. 
Very little is known of the development of the egg until 
the young fry enter the rivers in June. When they arrive 
in the rivers they are about three-quarters of an inch in 
length, perfectly transparent, without any colour, but their 
eyes are dark blue and iridescent, and one is able to detect 
them by that. 
They proceed up the rivers, and live in the fresh-water 
and estuaries until they return to the sea for spawning 
purposes in November and December. The old fish, after 
spawning, return to the rivers in the middle of May and 
during June. They proceed up the rivers for long dis- 
tances, having been taken at Clitheroe and Whitewell in 
Bowland, distances of over 30 miles from the sea. 
The flounder is easily distinguished from the plaice or 
dab by the china-white colour of the under-surface, resem- 
