380 HERBERT P. JOHNSON. 



appears in Fig. 3, are not limited to any particular part of the 

 coelom, but are loose and generally diffuse. Sometimes, how- 

 ever, they are massed in such a way as to give the impression of 

 a definite organ or testis, as shown in Fig. 5. The position with 

 relation to the ovum and intestine here shown is not constant. 

 The spermatocytes in the " testis " are not obviously at a different 

 stage from those free in the ccelom. This male gonad has not 

 been found in all the specimens. 



The mode of exit of the genital products offers an interesting 

 problem. It is well-known that in many Polychaeta they find 

 their way to the outer world through the nephridia, some of 

 which (as in Macellicepliala violacea, recently described by Wiren, 

 '07) may be specialized for this function. This evidently has not 

 taken place in Lycastis quadraticeps. What little has been made 

 out regarding these organs shows that they are extensive, con- 

 voluted tubules with a very narrow lumen, lying just in front of 

 the septum of each somite (Fig. 3, n. t.). The lumen does not 

 exceed in diameter one of the sperm-cells. While, so far as ap- 

 pearances go, it is entirely feasible for the spermatozoa to pass out 

 through the nephridia, the same cannot be said with regard to the 

 ova. It is obvious that they can escape only by rupture of the 

 body- wall and consequent destruction of the parent. This is well 

 known to be the only mode of exit in many of the Polychaeta. 

 It explains the fewness of ova in immature stages, which must in 

 fact on this hypothesis be regarded as aborted ova, for the death 

 of the parent in ovulation must preclude their completing their 

 development. No immature sperm-cells have been found. 



There appears to be no provision against self-fertilization, but 

 it may nevertheless exist in the form of protandry or protogyny. 



General Considerations. 

 Hermaphroditism among the Polychaeta is of such rare oc- 

 currence that up to 1855 it was supposed to be wholly absent in 

 the group. Even to-day, among the hundreds of known species, 

 very many of which have been studied in their sexual phases, 

 less than a score are known to be hermaphroditic. Although so 

 few, the hermaphrodites are pretty well scattered throughout the 

 entire subclass, as the following list will show. It is probably 

 incomplete. 



