100 A ren icolidae 



for bait. 1 It forms an excellent bait for flat fish, is also good for 

 Gadidae in general haddock, cod, whiting, and is used as a general 

 bait for lines on both sides of the North Atlantic. 



Although certain beaches have been regularly despoiled of 

 Arenicola marina for use as bait, this worm is still present there in 

 practically undiniinished numbers. Prof. M'Intosh suggested that 

 the worms have "resisted the attacks of man because a sufficient 

 stock of ripe examples and the very young are covered at all times 

 by the tide." There are certainly plenty of old examples in the area 

 covered by the tide, judging from the large specimens obtainable at 

 low tide. How far seawards the worms extend it is impossible to 

 say, but no doubt there are very substantial reserves always covered 

 by the sea. Even in the area exposed at an ordinary tide, the 

 number of worms is so great that the removal of those collected at 

 any one gathering of bait makes no appreciable diminution. For 

 instance, the area from which the Musselburgh fishermen dig their 

 bait probably contains at least three millions of the worms, and 

 therefore the removal of a few thousands per day produces little 

 effect on the numbers accessible at ordinary low tides. 



PERIODS OF MATURITY. In north-western Europe A. marina has 

 two periods of maturity annually, namely, about February to April, 

 and about July to September. 



At the conclusion of the larval development, which is unknown, 

 the post-larval stage (described on pp. 77-79), enclosed in a mucous 

 tubular envelope (PI. X, Fig. 26), becomes for a time pelagic. As a 

 rule the worm settles down to its littoral habitat before gills are 

 formed, but these organs develop almost immediately. 



Young specimens, 17 mm. long, from the sand, taken near the 

 end of June, possessed the full number of gills, already well branched ; 

 and in every respect, other than the gonads, the worms had 

 assumed the adult form. Probably these worms were produced from 

 eggs laid in the preceding February or March, and were thus about 

 three to four months old at the time of capture. Nothing is known 

 definitely regarding the correlation between the size and age of the 

 subsequent stages of development ; specimens five or six inches 

 long are probably about a year old, but no estimate can be given of 

 the age of the large examples obtainable at low spring tides. 



1 The only other Polychaeta at all commonly used as bait in this country 

 are certain Nereids, e.g. Nereis (Alitta) virens. Large quantities of Hermellids 

 are used for bait in the neighbourhood of Marseilles. 



