542 



F. W. GAMBLE AND J. H. ASHWORTH. 



^y., 



A. ecaudata. 



.^ ^. 



u^ ^< 



%< 



L«^ ^. 



,i^ 



^, 



A (jrubii. 



A.marina . 



Acristata 



Adaparedii. 



The Grst twenty cbsetigerous segments of Ave species of Arenicola to sliow 

 tlie chief external cliaracfers. The horizontal lines represent the 

 boundaries between the segments. Prost. Prostomiuni. Of. Otocyst. 

 N.O}-^^- Nephridiopores. Br}'^^- Gills. 



