286 LOUISE HOYT GREGORY. 



ciliated organ and nephridium developing in union with one an- 

 other. The form of the ciliated organ is also quite different from 

 that of Irma. There is no resemblance to a "trumpet-shaped 

 organ," the organ being in the form of a flat, triangular mass, as 

 has already been stated, and is united at one point only, not en- 

 tirely surrounding the nephridium as in Irma, yet the rolling of 

 t he dorsal and ventral edges may indicate an incomplete funnel. 



Fage 1 has worked on these segmental organs in a number of 

 forms in this family, and has found that in Ophiodromus flexuosus, 

 Oxydromns propinqims, Kefersteinia cirrata, there is found a 

 simple nephridium, slightly convoluted, opening to the exterior by 

 a pore found in the region at the base of the parapodium, and 

 into the body cavity by a straight nephrostome. At the mo- 

 ment of sexual maturity a ciliated organ formed from the peri- 

 toneum, is united with the nephridium and the sex products pass 

 out through the compound organ. Goodrich did not observe 

 this fact while working on the same forms. 



In Hesione pantherina, the segmental organ is different, the 

 excretory tube has many convolutions, the nephrostome is well 

 developed possessing long cilia, the entire organ is much more 

 highly modified than in other members of the family, and it 

 closely resembles the excretory organ of the Lycoridea. At the 

 time of sexual maturity, the organ undergoes no transformation. 

 A ciliated organ homologous with that described in other forms 

 of this group, is found near the nephrostome. It resembles the 

 dorsal ciliated organ of Nereis. This organ develops at the same 

 time as the nephridium and persists as an independent structure 

 throughout the life of the individual. At its base is found the so- 

 called phagocyte organ, containing in its meshes, granules com- 

 parable to the amcebocytes of the ccelome. 



Thus we see that when the nephridium is highly developed 

 and adapted more perfectly to its excretory function, it becomes 

 more and more useless as a genital duct, and we find a special 

 genital funnel appearing independent of the nephridium, and serv- 

 ing as a means of discharge for the sexual products. By this 

 form, the family of Hesionidae is closely connected with the family 

 of Nereidae. 



1 Fage, Louis, " Organes segmentates des annelides Polychetes," Annates des 

 Sciences Nattirelles, Tome III., 1906. 



