Japanese Palolo, ceratocephale osaWaî, x. sp. 19 



aperture to the continuous body-cavity at the hind end of the 

 epitoca, and the genital products may find their way outwards 

 through that aperture, assisted without doubt by the muscular 

 exertions required for swimming. Only an insignificant quantity 

 of genital products is extruded through the nephridial openings, 

 as I know from direct observations. At any rate, there can be 

 no doubt that the nephridial organs play quite an unimportant 

 l'ôle as genital outlet in comparison with the rent at the posterior 

 end or with the ruptures which subsequently occur in the general 

 body-wall. 



2. Observations on the Mature Phase. 



Ceratocephale osaicai, on attaining the epitocous phase. (PL 

 I., figs. 6, 7), i.e., the stage of sexual matruity in which it swarms 

 out for the purpose of breeding, differs in general appearance 

 from the immature or atocous worms so considerably that it may 

 at first sight easily be considered as specifically distinct. But 

 my direct observations on the life-history of the species, as also 

 the occurrence of forms representing intermediate transitional 

 stages, have placed the developmental relation of the two phases 

 beyond the reach of doubt. 



The best method of capturing the swimming worms is to 

 use a hand-net. If the night be rough or rainy, the worms do 

 not come quite to the surface of water. In such a ease I have 

 preferred to use the sort of a fine-meshed hand-net, which is 

 commonly employed in Tokyo for the capture of Saranx microdon 

 in the spring. This net, as set in frame, is triangular, with 

 sides of about six feet length each. It is dipped into the water 



