728 EDWIN S. GOODRICH. 



tinguislied (excepting, of course, by their histological 

 structure and position). The nephridium thus acquires a 

 large trumpet-shaped opening into the coelom, and functions 

 both as a genital, and as an excretory duct (Fig. H). 



In young Syllidae the genital funnel can scarcely be said 

 to exist, being represented only by a few crowded cells in 

 the coelomic epithelium on the anterior face of the septum, 

 just above the opening of the small nephrostome into the 

 ccelom. In those Syllids, like Autolytus, Myrianida, and 

 Haplosyllis, which become differentiated into vegetative and 

 reproductive regions or buds, the genital funnel advances 

 little beyond this very rudimentary stage in the regions from 

 which genital products are not extruded. But in the seg- 

 ments from which the mature genital cells are shed, the 

 genital funnel develops into a large trumpet-shaped organ 

 fused on to the anterior end of the nephridium. The canal 

 of the latter becomes dilated, and through this compound 

 structure ova or spermatozoa pass out to the exterior (Fig. I). 



In the remaining great families of the Polychasta — the 

 Eunicidf©, Amphinomidee, Aphroditidas, Spionidse, Arenico- 

 lidae, Terebellidae, Sabellidae, and their allies — the excretory 

 organs are always provided in the adult with large funnels 

 opening into the ccelom, and function as a rule both as renal 

 and as genital ducts. The structure of these organs is 

 sufficiently well known, through the labours of Ehlers (6), 

 Claparede (2), Cosmovici (3), Cunningham (4), Meyer (22), 

 and others, not to need a detailed description in this paper,^ 

 In all essentials they very closely resemble the compound 

 nephridia of such a form as Irma (Hesionid). The upper 

 lie of the funnel usually extends for a considerable way 

 on the anterior surface of the septum (when it is present) 

 and on the body wall (fig. 21). In some worms the anterior 

 organs alone may act as genital ducts, as in the Polynoinse 



1 I have recently investigated the structure of the excretory organs of 

 Saccocirrus; but since it appears to be a very highly modified form, and does 

 not seem to throw much light on the general question here discussed, I shall 

 reserve my description for a future paper. For Polygordius see p. 715. 



