1885.] Nephridia of a New Species of Earthworm. 461 



A discussion of certain other questions in the morphology of earth- 

 worms, naturally arises out of the foregoing facts. Professor Lan- 

 kester, in a memoir upon the anatomy of Lumbrieus* called attention 

 to the fact that there is a constant and definite relation between the 

 nephridial aperture on the one hand, and the apertures of the genital 

 ducts on the other hand, to the setae ; the nephridia open close to the 

 ventral pair of setae, the genital ducts and copulatory pouches have a 

 similar relation to the dorsal pair. Claparede had previously 

 expressed the opinion that in the Limicolous Oligochaeta, the ducts of 

 the genital system were the modified representatives of the ne- 

 phridia, basing this opinion on the general similarity of structure and 

 position, and more especially upon the fact that nephridia are absent 

 in those segments of the body which contain the genital ducts ; he 

 denied, however, that this comparison could be applied in the case of 

 earthworms, since here the genital^ducts coexist in the same segments 

 with nephridia. Professor Lankester, in the paper just referred to, 

 pointed out that Claparede's views could be extended to earthworms, 

 if it were admitted that each segment of the body were typically 

 furnished with two pairs of nephridia, one corresponding to each of 

 the pairs of setae. Professor Lankester supposed that in Lumbrieus 

 the copulatory pouches and genital ducts were the modified repre- 

 sentatives of the second series of nephridia, which had disappeared 

 elsewhere than in the genital segments. Certain facts in the anatomy 

 of other genera of earthworms, made known by the researches of 

 M. Perrier, appeared to lend very strong support to this hypothesis. 

 M. Terrierf has described certain earthworms (Acanthodrilus, 8fc.) 

 which agree with Lumbrieus in that the nephridia open on to the 

 exterior of the body by the ventral setae ; in others again {e.g. 

 Anteus, Bhinodrilus) the nephridia are related to the dorsal pair of 

 setae; finally, in Plutellus,^ there is an actual alternation in the 

 position of the nephridial orifices, in some segments they open near 

 to one of the dorsal pair of setae, in others near to one of the ventral 

 pair. All these facts seem to be best explained by supposing the typical 

 presence of two series of nephridia, a dorsal and a ventral, one or 

 other of which has partially or entirely disappeared ; in Lumbrieus 

 the dorsal series has disappeared, in Anteus the ventral series ; while 

 in Plutellus, both dorsal and ventral series have partly persisted. 

 Although this hypothesis serves to explain the series of facts which 

 have been briefly stated above, M. Perrier has come to the conclu- 

 sion that it cannot be adopted in the way that Lankester has sug- 

 gested, inasmuch as there are reasons for disbelieving in any 

 homology between the nephridia and genital ducts. If the orifices of 



* " Quart. Journ. Micr. Sci.," 1865. 

 f " Nouv. Arch. d. Museum," t. viii. 

 % " Arch. d. Zool. Exp.," t. ii. 



