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Mr. F. E. Beddard. On the 



[June 18, 



the nephridia were always constant to a series of setae different from 

 that to which the orifices of the genital ducts belong — as in the case 

 of Lumbricus — then it would be permissible to retain the hypothesis of 

 two series of nephridia. Such, however, is not the case ; in Urochceta 

 and in Plutellus, the orifices of the copulatory pouches coincide at 

 the same seta as the orifices of the nephridia ; and it also difficult to 

 explain the fact that the vasa deferentia traverse several segments, 

 all furnished with distinct nephridia, on their way to the exterior. 



It appears to me that the coincidence of nephridium and copulatory 

 pouch at the same series of setae is not a serious objection to Professor 

 Lankester's hypothesis. It is extremely possible that the copulatory 

 pouch may be the equivalent of a diverticulum of the duct of the 

 nephridium ; such diverticula I have myself described in a large 

 earthworm (Microchceta) from the Cape Colony in a paper read before 

 the Zoological Society, and they exist elsewhere. In Microchceta there 

 are no proper copulatory pouches ; these structures appear to be 

 functionally replaced in four segments of the body by several extremely 

 minute caecal pouches placed in the immediate neighbourhood of the 

 nephridium of their segments. M. Perrier* has described in a species 

 of Perichceta similar accessory pouches having a precisely similar 

 relation to the copulatory pouches ; and in my paper I have called 

 attention to the great resemblance between the copulatory pouch of 

 this Perichceta with its independent accessory pouches, and the 

 nephridium of Microchceta with its large muscular diverticulum and 

 the series of similar caecal pouches. I have also illustrated the com- 

 parison by figures, which will be shortly published. 



Whatever may be the value of M. Perrier's criticisms of Professor 

 Lankester's hypothesis, it is quite clear now that there is no intrinsic 

 improbability in this hypothesis. The new facts that have been 

 brought forward in the present paper also serve to render intelligible 

 certain other facts in the morphology of earthworms. 



In his earliest paper on the anatomy of earthworms, M. Perrier 

 adopted the hypothesis of two series of nephridia, one corresponding 

 to each pair of setae in those earthworms that are famished with four 

 pairs. In Lumbricus the two setae of each pair are closely approxi- 

 mated, but in many other earthworms, as in the Acanthodrilus, which 

 forms the subject of the present communication, the two setae of each 

 pair become widely separated, so that there are eight longitudinal 

 series of a single seta each ; in these cases it is important to know 

 what becomes of the nephridial orifice ; has it, in fact, any definite 

 relation to one or other of the two setae of the pair ? M. Perrier has 

 addressed himself to this question, and has recorded the fact that in 

 Anteus, Bhinodrilus, and Moniligaster, where the ventral series of 

 nephridia are alone present, their orifices are situated close to the 

 * "Nouv. Arch. d. Museum," t. viii, PI. IY, fig. 72. 



