THK STRUCTURE AND AFFINITIES OF SACCOCIRRUS. 413 



On the Structure and Affinities of Saccocirrus. 



By 



Edwin S. Ciroo«1ricli, I?I.Am 



Fellow of Mertoii College, Oxford. 



Witli Plates 27—29. 



When studying the morpliolog-y of the excretory organs 

 of the Polychffita, 1 thought it advisable to investigate those 

 few cases of worms in which the true nephridia have been 

 alleged to function as genital ducts. Of these Polychsetes, 

 Saccocirrus papillocercus, Bobr., is one of the most 

 interesting; and whilst occupying for a short time last 

 winter, at the Zoological Station at Naples, a table kindly 

 placed at my disposal by the committee of the British 

 Association, I had an opportunity of studying its structure. 



Unfortunately the results are somewhat disappointing, 

 since I have not been able to discover an}' facts of such 

 decisive significance as to settle the difficult question of the 

 morphological value of the organs Avhich contribute to form 

 the complex genital apparatus of this little worm. However, 

 as I was able to complete and to correct the accounts of 

 previous authors in many points of detail, 1 publish this 

 paper as a small contribution to the subject, and have 

 appended some general remarks concerning the validity of 

 the group " Archi-anuelida." 



Marion and Bobretzky,^ in 1875, published an excellent 

 account of the structure and habits of Saccocirrus, from 

 material studied at Mai'seilles (10). Since then Langerhans 



' Bobretzky's original paper (1) I have iiol been able to consult. 



