This paper is the fourth in a series dealing with the fecundity of flatfish (Bagenal 1957 a,b, 1958), and is concerned with the egg numbers in ripening female plaicePleuronectes platessa L. caught in the English Channel.

On 27 November 1957, eighty-five plaice with maturing ovaries were caught in Rye Bay, Sussex; on I December, eight similar fish were caught in Lyme Bay, and duringDecember sixty-four locally caught female plaice were brought in to the Plymouth Laboratory. The dates of the collections were chosen because in January 1957 I had found that a small proportion of the Plymouth plaice were spent. All the fish caught in November and December were at a suitable stage for fecundity estimation: that is, the eggs were well developed though none had begun to turn translucent.