714 EDWIN S. GOODRICH. 



genera of the Hesionidae has proved to be of such remark- 

 able interest with regard to the connection gradually estab- 

 lished between the nephridium and the genital funnel, to the 

 substitution of the latter for the real nephrostome, and to the 

 formation of a compound organ — giving us a series of steps 

 bridging over the wide gap which separates the structure of 

 such a form as Nereis on the one hand, and the Syllids on the 

 other, — that I deemed it advisable to return to the considera- 

 tion of this family. 



The two species I shall describe are Ophiodrom us flexuo- 

 sus D. Ch., from Naples, and Ir mala t if rons, Gr., for which I 

 am indebted to my friend Dr. Willey, who brought a number 

 of these worms back from New Guinea. 



It will be remembered that in Hesione the nephridium 

 possesses its own nephrostome, which, however, is united with 

 the lai'ge genital funnel at one point (11, fig. 2). In Ophio- 

 dromus the genital funnel is much smaller (figs. 22, 25, and 

 26), at least in the specimens I have examined, which are not 

 quite genitally mature ; but it is more intimately connected 

 with the nephridium, so completely surrounding the internal 

 opening of this organ that the nephrostome can scarcely be 

 said to exist as such any more (figs. 25 and 26). 



Series of sections through young and mature specimens of 

 Irma show that the genital funnel becomes increasingly large 

 as age advances, until in quite ripe individuals it is very 

 extensive indeed, spreading over the large blood-vessels and 

 the inner side of the body-wall near the base of the parapo- 

 dium (figs. 19 and 50). The nephridium fuses with it, and 

 the compound organ so formed serves as a genital duct. In 

 the specimen figured, a ripe male, spermatozoa can be seen in 

 the nephridial canal on their way to the exterior. 



The minute structure of the genital funnel in Irma, with 

 its numerous ridges on the ciliated surface, is exactly like that 

 of its homologue in Nereis and Hesione, which I called the 

 "^ ciliated organ" (fig. 19). 



We have, then, in these^ genera Ophiodromus and Ii'ma (to 

 which may also be added Kef ersteinia) organs, acting both as 



