186 E. S. Goodrich. 



in a position to bring' forward further evidence in favour of a 

 Suggestion made as to how the grafting of the two organs of such 

 different origin and function may have taken place (p. 732 J )). 

 Nephromixium is the name given to the Compound structure so 

 form ed. 



First of all let us re-examine the excretory organ of Alciope 

 hröhnii. In an immature specimen the nephridium, as in all Alciopids, 

 is very long, with a sl ender straight tube opening behind ventrally 

 near the base of a parapodium, and passing forwards towards the 

 next septum. It pierces the septum, projecting into the coelom of 

 the next segment, where it ends in a slightly expanded blind 

 extremity on which are set groups of solenocytes. These have 

 already been described in detail ] ), and I need only State that the 

 cell bodies are placed at the ends of slender tubes down which a 

 long flagellum works into the lumen of the nephridial canal. Actively 

 moving cilia, set on the outer surface of the nephridium agitate 

 the coelomic fluid in the immediate neighbourhood of the soleno- 

 cytes. 



The first four or five segments are provided with such simple 

 nephridia. But from the 9th segment backwards there can be 

 seen a developing coelomostome on the front surface of each septum 

 near the nephridium. At the ninth segment the coelomostome is in 

 the form of a small almost flat patch of ciliated coelomic epithelium 

 (fig. 1). Passing to segments further back, this patch is seen to 

 enlarge, to become cup-shaped, and then to grow into a deep funnel- 

 shaped pocket, with an anterior truinpet-like opening and a blunt 

 posterior blind end. The septum itself is necessarily carried back- 

 wards with the growth of the coelomostome (Figs.2,3and 4). Towards 

 the hinder end of the body the coelomostomes again dwindle in size. 

 the most developed being in the mid-region. 



In the adult full-grown Alciope cmtramii the nephridium 

 acquires a large size, the inner extremity giving off short branches 

 beset with numerous solenocytes (Fig. 5). Here also the coelomostome 

 can be seen to grow from a smaal patch of ciliated coelomic 

 epithelium on the front face of the septum, and to enlarge into a 

 bell-shaped funnel. In the male this becomes crammed with spermato- 

 zoa, and acts as a sperm-vesicle. At maturity the posterior blind 

 end fuses on to the nephridial canal. flnally opening into it 



1) Goodrich, 1. c. 



