ON A NEW ORGAN IN THE LTCOEIDEA. 387 



On a New Organ in the Lycoridea, and on the 

 Nephridium in Nereis diversicolor, O. 

 F. Mull. 



By 



E. S. Ooodiicli, FX.S., 



Assistant to the Linacre Professor of Human aud Comparative Anatomy, 



Oxford. 



With Plates XXXIV & XXXV. 



About two years ago, while examining some sections of a 

 Nereis (probably N. diversicolor, O. F. MiiU.) which I had 

 cut in the Zoological Laboratory at University College, London, 

 I discovered an interesting organ, which appears to have 

 hitherto escaped the notice of those naturalists who have 

 studied the anatomy of the Nereids. Since then I have from 

 time to time continued my observations, both in London and 

 in the Oxford Museum, always hoping to be able to obtain the 

 stages in the development of Nereis, the study of which alone 

 can give a real clue to the homology and functions of these 

 organs. This unfortunately has not been possible, owing 

 chiefly to the fact that I have not been able to go myself to 

 the sea-side to pursue my researches. It has therefore been 

 thought advisable to publish the facts as they stand, and this 

 paper amounts to little more than a mere description of this 

 new organ. Some notes on the minute structure of the ne- 

 phridium of the Nereids have also been added. 



Various genera and species were examined, but most of the 

 observations were made on Nereis diversicolor, which 

 occurs in abundance at Plymouth, whence I have obtained 



