184 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Mr. F. W. Gamble and Mr. J. H. Ash worth, of Owens 

 College, Manchester, spent three weeks of the Easter 

 vacation, 1897, at the Port Erin Biological Station, working 

 at the anatomy of the species of Arenicola, and Mr. Gamble 

 again visited the Station for a few days at Whitsuntide 

 for further research into the same subject. The following 

 is a summary of the results obtained : — 



" The shores of Port Erin and Port St. Mary are 

 inhabited by three well-marked species of Arenicola, A. 

 marina, A. ecaudata, and A. grubii. The best known of 

 these, A. marina, the common 'lug-worm,' is represented 

 on the coarse sandy beaches by the small littoral variety 

 characterised best by the delicate gill plumes being each 

 composed of four or five lateral branches on either side of 

 the main vascular axis, and by constructing U-shaped 

 galleries in the sand. In the gravel and amongst the 

 debris of decomposing rock on the shore of Bay-ny- 

 Carrickey a large, dark variety occurs with gills of the 

 same type, but strongly pigmented. The blood-vessels 

 are very large and turgid. This variety, which may 

 attain a length of one foot, is distinguished by the form 

 of its gills from a somewhat similar, dark, bulky variety, 

 occurring at extreme low water on the Lancashire coast 

 (and known to the fishermen as ' worms,' in contradis- 

 tinction to the littoral form or 'lugs'), in which the 

 gills have ten or eleven lateral branchlets, and hence a 

 pinnate form. This 'Laininarian' variety has not hither- 

 to been found at Port Erin, but this is probably due to the 

 great depth (up to four feet) to which it is known to 

 burrow. 



" The two species A. grubii and A. ecaudata belong to 

 a division of the genus characterised by the continuation 

 of the gills and parapodia to the hinder end of the body. 

 They are distinguished from one another by important 



