234 fROF. W. A. HASWEL1, i 



Meanwhile the rudiments of the testes have appeared as masses of narrow 

 tubes surrounding the nephridia closely and extending round the intestine 

 towards the dorsal side. The origin of these testicular masses is difficult to 

 trace. They are developed in close association with the nephridial tubes and 

 are composed of cells at first very similar to the cells composing the walls of 

 these tubes. But they are also from the first, or from an early stage, closely 

 associated with the peritoneal lining of the sides of the intestine. 



Before the testes are formed, or while they are still small, there is to be 

 seen in the living animal in front of the nephridium a colourless thin-walled 

 sac which contracts at intervals. This must correspond to the dilated end of 

 the vascular caecum described by Malaquin (p. 383) as forming the axis of 

 the testis in the Syllidse. It becomes hidden in Exogone fustifera when the 

 testes develop, and I have been unable to trace it in sections. Its equivalent 

 in the female is referred to above. 



Later, when masses of sperms have been set free in the coslom, the nephridia 

 come to be represented by two relatively wide tubes (PI. 18. fig. 43), one on 

 either side, still connected with the nephridiopore and provided with a ciliated 

 nephrostome. Each becomes a sac with narrow lumen and thick wall com- 

 posed of numerous small cells. The lumen of each sac increases in extent 

 (PI. 18. fig. 44) and the cavities of each pair at length unite, though partly 

 separated for a time by a septum which at last disappears, the wall of the 

 unpaired sac (PI. 18. fig. 45) thus formed becoming at length thinned out 

 till it assumes the character of a single layer of small cells. 



The presence in E. clavigera of " vesicules seminales " which were in all 

 probability formed each by the fusion in the middle line of a pair of 

 nephridia was observed by Claparede (2. p. 212). He does not describe a 

 corresponding fusion in the female. 



Viguier (34. p. 86) agrees with Claparede regarding the unpaired pouches 

 of the male, but describes them as opening behind and not in front of the 

 ventral cirri. In the ripe female he describes (p. 88) the two ova in each 

 segment as increasing in size till they meet below- the intestine, and one may 

 pass in front of the other. From the results of compression he concludes 

 that the apertures of egress are in front of the base of the parapodium. 



De St. Joseph (31. p. 86) confirms Claparede's account as regards the 

 male. With regard to the female he states : — " Une femelle de 25 segments 

 a dans les lOe.a 23e. segments une masse vitelline grise sans noyau, entouree 

 d'une membrane et commeneant a se segmenter en deux; situee sous le 

 ventre entre l'intestin et la paroi du corps elle occupe presque toute lalargeur 

 du segment. Est-ce une poche renfermant deux oeufs dont je n'ai pas vu le 

 noyau et que commence a se separer en deux ? Est-ce un oauf unique a son 

 premier stade de segmentation ? " 



Grubea pusllloides has the sexes united. The occurrence of this condition, 

 so rare in the Polychasta, has been recorded by Du Plessis in another species 



