210 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Introduction. 



Arenicola* is a genus of abundant and widely- 

 ranging Polychset worms, represented in the British 

 fauna by three species, t all of which may he found 

 between tide marks in the neighbourhood of Port Erin 

 (Isle of Man) and Plymouth. 



The common lugworm, Arenicola marina, forms a 

 convenient type of the genus. It is abundant on most of 

 the sandy shores around the British Isles. Its presence 

 is indicated by the small heaps or coiled castings of sand, 

 which are familiar objects between tide marks. The 

 animal may be found on digging to a depth of one to 

 three feet near such castings, and it is commonly so 

 obtained by fishermen, by whom it is extensively used as 

 bait.+ Its general appearance may be seen in Fig. 1. It 

 is almost invariably slightly inflated in the anterior 

 region, being widest at a point about one-sixth of its 

 length from the anterior end. 



Habits, Yarieties. 



There are on the Lancashire coast and in the Firth of 

 Forth, two varieties of A. marina which differ in habits 

 and in two structural points. 



* While the following account owes much to the memoir published 

 in 1898 by Dr. F. W. Gamble and myself (Quarterly Journal of 

 Microscopical Science, Vol. 41) it should be said that a large portion 

 of it is new, consisting of observations on the development and post- 

 larval stages and of new points relating to some of the systems of 

 organs. All the statements from the earlier memoir used in the 

 present one have been carefully revised and some of them corrected in 

 the light of further investigations I have made on the genus during 

 the last six years. 



t A. marina, Linnseus; A. grubii, Claparede ; A. ecaudata, 

 Johnston. 



I I have added a section (see p. 299) dealing with some points of 

 economic importance, such as its abundance in various sands, its 

 efficacy as compared with that of other bait, etc, 



