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MONTGOMERY— MORPHOLOGY OF THE 



[April 24, 



join secondarily with the nephriciium proper that develops inde- 

 pendently from retroperitoneal tissue.^ But it is Goodrich who has 

 made the most comprehensive comparative investigation of these 

 relations (1895, 1897, 1898, 1900). He calls the peritoneal funnel 

 (Genitalschlauch) a coelomoduct, and its opening a coelomostome ; 

 when the latter preserves its original strictly genital function it is 

 a gonostome. According to his terminology, further, a nephridium 

 is an excretory organ with its own inner opening, and the latter 

 is a nephridiostome. The coelomoducts may open on the surface 

 of the hody entirely separate from the nephridia, the primitive con- 

 dition, and in this case the nephridia are purely excretory and 

 possess small nephridiostomes ; or the coelomostomes may become 

 secondarily grafted upon the nephridia, forming compound nephro- 

 inixia which are genito-urinary and possess large funnels (coelomo- 

 stomes). These relations in the Polychsetes he tabulates as fol- 

 lows (1900) : 



Nephridium 



closed 

 internally. 



Nephridium 



open 



internally. 



Genital funnel distinct, but open- 

 ing into nephridial canal may be 

 acquired at maturity. 



Phyllodqpidse. 

 Glyceridae. 



Neplithyidae. 



Genital funnel ^vith independent ex- ( Capitellidse. 



ternal opening. 



Genital funnel becomes connected 

 with the nephrostome, and loses 

 its primitive opening to the ex- 

 terior. 



? Nereidae (Lycoridea). 



Hesionidas (all?). 



Syllidas. 



Aphroditidse. 



Eunicidae. 



Spionidae. 



Terebellidae. 



Sabellidje. 



Etc., etc. 



Goodrich adduces the various evidence for this conclusion and 

 adds : " Moreover, it must be remembered that the two organs are 

 mutually exclusive; never do we find a separate genital funnel in 

 those forms which possess wide-mouthed excretory organs; and 

 conversely, with the one possible exception of Polygordius, never 

 do we find Polychsetes having nephridia with only small true nephro- 



^ Meyer (1890) has shown that Kleinenberg (1886) was mistaken in 

 deriving the genital ducts from the ectoblast. 



