ON THE NEPHRIDIA OF THE POLTOH^ETA. 185 



On the Nephridia of the Polychaeta. 



Part I. — On Hesione, Tyrrhena, and Nephthys. 



By 



Edwin S. Ooodi'ich, B.A., 



Assistant to the Linacre Professor, Oxford. 



With Plates 6—9. 



The following observations on Hesione sicula, Dch. 

 (Fallacia sicula), and Tyrrhena Claparedii, Quatref., 

 were begun last year at Naples^ and completed at Oxford ; 

 those onNephthys scolopendroides^ Dch., andNephthys 

 csecaj Fabr., were begun at RoscoflF, continued at Naples, and 

 finished here.^ The material was examined in all cases both 

 fresh and preserved. 



Hesione. 



The Ciliated Organ. — When full grown, Hesione 

 sicula is of about the size and appearance of Peripatus 

 capensis, and can be easily dissected. On opening up the 

 worm dorsally, and turning back the cut edges of the body- 

 wall, the segmental dorso-lateral blood-vessels are seen ex- 

 tending outwards from the intestine to large bundles of oblique 

 vertical muscles attached to the body-wall between each pair 

 of parapodia. On reaching these bundles the vessels pass 

 downwards amongst the muscles, and reappear near the median 



' I must express my sincere thanks to the directors and staff of the Zoolo- 

 gical Stations at Naples and at Ex)scoff for the kind and helpful way in which 

 they received me. 



