ON THE 0(ELOM, GENITAL DUCTS, AND NEPHEIDIA. 499 



Phoronis. 

 In the larva of Phoronis, Caldwell describes a pair of nephri- 

 dia, slender ciliated canals blind internally (21). Their origin 

 is still doubtful. The coelom is developed as two pairs of 

 follicles, of which the larger " posterior " pair is alone fertile. 

 The excretory organs of the adult consist in Phoronis 

 psammophila and Ph. Kowalevskii of a pair of peritoneal 

 funnels leading to the exterior from the " posterior" coeloraic 

 follicles (Cori, 23). According to Caldwell (22), they are 

 developed in connection with the nephridia of the larva, 

 and would appear to be of a compound nature like those of 

 Polychsetes. In Phoronis australis both the anterior 

 and posterior pairs of coelomic follicles are provided with 

 their peritoneal funnels, which open by a common duct 

 (Benham, 5). These funnels in Phoronis serve both as renal 

 and genital ducts. 



ECTOPROCTA. 



No true nephridia appear to have been found in these 

 Polyzoa. On the other hand there are two peritoneal funnels, 

 an excellent account of which has been given by Cori in 

 Cristatella (24). They differ from those of Phoronis only in 

 that they open by a common median pore. 



Brachiopoda. 



Here the coelomic follicles, formed as paired archenteric 

 pouches, are provided with a pair of wide-mouthed peritoneal 

 funnels opening to the exterior. They function as the carriers 

 both of excretory and of genital products, and possibly the 

 distal end of the organ represents the true nephridium (also in 

 the Ectoprocta), which has fused with the peritoneal funnel 

 (Morse, 83; Blochmann, 11). 



impossible that they may be formed not from the nephridia, but from those 

 late epidermal invaginations which, as we have seen, so generally occur in 

 connection with the external opening of the peritoneal funnels. In the Ar- 

 thropods above mentioned these funnels disappear in those segments which 

 possess tracheee. 



