ON THE NEPHRIDIA OF THE POLTCH^TA. 453 



In G. maculata^ the terminal organ of the nephridium is 

 much smaller, and appears in section as little more than a 

 bunch of solenocytes (fig. 39). 



The Ciliated Organ. — It has been my good fortune to 

 obtain a perfectly ripe male specimen of Goniada raaculata, 

 which proves, I think, beyond the possibility of doubt the fact 

 that the ciliated organ acts as a genital duct or 

 funnel, — in this species, at all events. This is all the more 

 gratifying to me, since I suggested that this is its function 

 when I first described this organ in the Lycoridea five years 

 ago (3). 



It will be remembered that Goniada is divided into two 

 dissimilar regions, somewhat as the heteronereid phase of 

 Nereis. Sections show that in the first few segments both 

 nephridia and segmental organs are absent; that in the 

 anterior region generally the nephridium is present, but the 

 ciliated organ not at all, or scarcely, developed. It is only in 

 the posterior region that this organ is fully formed in the 

 adult. In these segments it takes the shape of a wide- 

 mouthed funnel, a trumpet-shaped structure, the lips of 

 which spread and gradually thin out on the septum. Here 

 the thickened ciliated epithelium, of which the wall of the 

 funnel is formed, flattens out and passes into the ordinary 

 ccelomic epithelium lining the body-cavit}^ (^gs. 36, 39, and 

 31). Bunches of cilia may be seen on this epithelium some 

 way up the septum (fig, 36). 



The ciliated cells of the funnel are remarkably striated, and 

 the cilia numerous and very powerful (fig. 40). 



The funnel leads into a wide tube, which passes backwards 

 to join the nephridial duct behind the septum (fig. 36). 



The ciliated organ opens here into the lumen of 

 the nephridial canal, the junction or grafting of the two 

 organs being marked by quite a sudden change in the character 

 of the tissues. Behind this point the nephridial duct widens 

 out, and afi'ords an easy outlet to the spermatozoa, which in 



' The description applies to both sexes. 



