SEGMENTAL ORGAN OF PODARKE OBSCURA. 285 



observed by Treadwell, 1 the spindles may be formed after the 

 eggs have passed out of the body ; but, as a rule, the first spindle 

 appears while the egg is free in the body cavity, before its passage 

 into the nephridial cavity. In the male, the relations between 

 the nephridium and ciliated organ is the same as that in the 

 female, but the discharge of the spermatozoa was not observed. 



Goodrich 2 in his summary of the most important facts result- 

 ing from his study of the Hesionidae, says : Hcsione sicida has 

 a nephridium, which opens ventrally to the exterior, passes in- 

 wards and forwards, becomes considerably coiled, and finally 

 ends just in front of the intersegmental region by a small, simple, 

 funnel opening into the ccelome of the next segment. Con- 

 nected with the lip of the nephrostome by a narrow strip of epithe- 

 lium is a large crescentic genital funnel (ciliated organ), the cili- 

 ated surface of which is marked by deep grooves. Those of the 

 middle region converge towards the loose extremity of the organ, 

 where it is connected with the nephrostome and with the body 

 wall. The exact mode of exit of the genital products is unknown. 



In Tyrrhena, the nephridium is essentially the same but the 

 genital funnel is smaller and more closely connected with the 

 nephrostome. 



In Kefersteinia and Opkiodromus it completely surrounds the 

 inner extremity of the nephridium. 



Finally in Irma, where the nephridium is no longer coiled, the 

 large genital funnel surrounds and fuses completely with its inner 

 end, forming a trumpet-shaped ccelomic funnel. The genital 

 products, collected together by the action of its ciliated surface 

 pass down into the nephridium and so to the exterior by the 

 nephridiopores. 



Podarke seems to be most similar to Irma. In both cases, the 

 discharge of the genital products has been determined definitely 

 to be by means of the ciliated organ and nephridium. In Irma, 

 however, immature forms show the ciliated organ developing 

 separately from the nephridium, the union taking place when the 

 animal is sexually mature. In Podarke immature forms show the 



1 Treadwell, A. L., " Cytogeny of Podarke ooscura," Journal of Morphology, 1900- 

 1, Vol. 17. 



2 Goodrich, E. S., "On the Nephridia of the Polychseta," Quarterly Journal of 

 Morphology, vol. 43, 1900. 



