CH. IV] LIFE IN THE SEA 97 



the advent of myriads of nauplii of barnacles (Balamis) which at 

 times are found in the tow-nets to the practical exclusion of almost 

 everything else. Great numbers of these animals must spawn 

 simultaneously and very rapidly, for they appear to produce swarms 

 of larvae. After a short free-swimming existence these nauplii 

 moult and we then find that the tow-nets contain the bivalved 

 cypris stage of Balanus. These latter larvae linger on until the end 

 of the summer, but in April and May most of them must have 

 begun to adopt their adult habitat, for we find then that swarms of 

 young Balani have settled down on the stones, shells, piers, 

 sea-walls, &c. ; and on the hulls of the boats of the fishermen, in 

 spite of anti-fouling paint, assiduous scrubbing and doubtless 

 much profanity. 



At the beginning of March the crabs begin to spawn. The 

 distinction of the different crab zoeas is a matter of great difficulty ; 

 certainly there is much individual variation in the time of the 

 spawning ; and the larvae have, as such, a long life. Therefore we 

 find that most tow-nettings taken until the end of October contain 

 zoeas. At times the eggs carried by numbers of crabs must hatch 

 almost simultaneously, for we find tow-nettings which contain little 

 else than these larvae. 



May begins a new season. The diatoms have hitherto been 

 prominent plankton organisms, often to the practical exclusion of 

 everything else, but from now for a few months they begin to 

 decrease in numbers. The summer spawning fishes begin to shed 

 their eggs. Ling, turbot, anchovy, mackerel, stingfish {Trachinas) 

 and topknot {Zeugopterus) spawn in May, June and July. The 

 sole too spawns in June, though the eggs of this fish do not appear 

 in the inshore waters of Cardigan Bay and are not represented in 

 the diagram. Plutei of echinoderms appear in May for the first 

 time. Sometimes the beautiful long-spined plutei of the heart- 

 urchin {Echinocardium cordatum), a species which lives in the mud 

 in inshore waters, is so abundant as to crowd out other organisms 

 from the tow-net. In June the crab zoeas are undergoing their 

 metamorphoses into the Megalopa stage, and swarms of these 

 larvae appear at the surface of the sea, and also at the bottom, for 

 dabs may be taken with their stomachs distended with these 

 creatures. Megalopas are long-lived and November sets in before 



J. F. 7 



