822 MR. F. E. BEDDARD ON [NoV, 3, 



§ Nephridia. 



Hardly anything is known about the nephridia in the genus Acan- 

 thodrilus. Perrier does not refer to their presence in his description 

 either of the genus • or of the three species examined by him. A 

 statement that the apertures of these glands are placed above the 

 ventral pair of setae " implies, however, their existence. Dr. Horst * 

 failed to find any nephridia at all in A. schlegelii ; and in J. biittiko- 

 ferii they appear to be represented solely by a tufted organ in the 

 anterior part of the body, attached to the pharynx, which is probably 

 identical with the "salivary" gland of A. multiporus, to which I 

 have already referred. They are present in A. keryuelenensis and in 

 A. capensis. 



In all the three species described in the present communication 

 nephridia are found ; in ^. multiporus I have already * described 

 the structure and distribution of the nephridia. This species is appa- 

 rently unique among Earthworms in possessing a single nephridium 

 to each of the eight setae, the duct of which opens in close proximity 

 to the seta by a single orifice in the posterior part of the body ; in 

 the anterior part of the body the duct of each nephridium branches 

 and opens by a multitude of orifices. 



A. novce zelandice and A. dissimilis, the nephridia are remarkable 

 in that they alternate in position from segment to segment of the 

 body. It "is a general rule among Earthworms, possessing only a 

 single pair of nephridia iu each segment of the body, that the 

 position of the external apertures of these is constant. In Lumbricus 

 the nephridia are related to the ventral pair of setae, near to which 

 they open, and the same is the case with Eudrilus and several other 

 genera. Perrier discovered that in other genera (e. g. Ehinodrilus) 

 the nephridia bore a similar relation to the dorsal pair of setae or to 

 one of these setae, if the two had become separated, as is so often the 

 case. These facts led M. Perrier to support Prof. Lankester's 

 hypothesis of the typical presence of two series of nephridia ia 

 Earthworms corresponding to the two series of pairs of setae. 



The characters of the genus Plutellus appeared to be entirely 

 confirmatory of this hypothesis. In this Earthworm the setae are 

 disposed in* eight longitudinal rows of a single seta each, and the 

 external orifices of the nephridia alternate in position from segment 

 to segment, sometimes being situated near to one of the two dorsal 

 setae, sometimes near to one of tlie ventral setae. I have elsewhere 

 pointed out that these facts really indicate the partial persistence of 

 four series of nephridia' corresponding to the four rows of setae, 

 and entered to some extent into the questions raised by Prof. 

 Lankester's hypothesis, so that I need not recall the matter. 



In A. nova zelandice and dissimilis, where, as has already been 



' Nouv. Avcb. &c. p. 8.J. 

 2 Loc. cit. p. 162. 



^ Notes from Leyden Museum, vol. vi. pp. 10.5, 107. 



■• Proc. Roy. See. uo. 238, 1885, p. 459. See alao a forLhcoiuing paper in 

 Ann. Sci. Nat. 



° Proc. Eoy. Soc. loc. cit. 



