304 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



stages of development are passed there. The larva? grow 

 until the full number of adult body segments has been pro- 

 duced and then enter upon the pelagic post-larval stage. 

 This is the earliest known stage of development of the com- 

 mon lugworm. The young worms do not settle down to their 

 littoral habitat and characteristic mode of life until they 

 have attained a length of about 5 to 7 mm. Young speci- 

 mens 17 mm. long have been found in the sand in June. 

 Although it is difficult to estimate their age, it may be 

 suggested that these specimens 17 mm. long and others up 

 to 44 mm. long taken near the end of June were probably 

 produced from ova laid in the preceding February or 

 March. If that be the case, then worms five or six inches 

 long are probably about a year old. Some of the large 

 deeply-pigmented specimens obtainable at low spring tides 

 are certainly much older, but on this point no information 

 is available. It may be taken that the smaller specimens 

 of Arenicola used as bait are at least a year old. Con- 

 sidering the abundance of Arenicola on many beaches, it 

 is astonishing that we know so little of its life history, and 

 that so few post-larval stages have been taken in the tow nets. 

 The present state of our knowledge does not permit 

 one to make any suggestions with regard to the possible 

 cultivation of lugworms in any given area in which they 

 are wanting. The writer has made several attempts to 

 fertilise artificially the ova of the common lugworm 

 removed from a ripe female, by adding spermatozoa 

 obtained from a mature male, but without success, 

 although both ova and spermatozoa appeared, when 

 examined microscopically, to be quite ripe and favourable 

 to the experiment. Others have also experienced these 

 failures when dealing with this and other species of 

 Arenicola* Evidently, therefore, it is more difficult to 



* I eventually succeeded in fertilising artificially the eggs of 

 A. claparedii. For an account of the early stages of development of 

 this species, see p. 263. 



