tliodrilus multiporus''\ he has described eight nephridia per somite: 

 one corresponding to each of the eight setae, which in this species are 

 separate. 



In A. dissimilis: and A. novae -zelandiae^ the nephridia are limi- 

 ted to the usual one pair per somite : but they alternate in position, 

 from somite to somite, as in Flufellus'^ : but in Acanfhodrihis the dorsal 

 nephridia differ somewhat from the ventral series. 



In other species oi Acanthodrilus , in some Perichaeta, and in Tri- 

 gaster which may, herhaps , be a species of Acanthodrilus, as 

 Mr. Horst has recently, suggested) the nephridia are represented 

 by scattered tuft-like masses of tubules having all the appearance of 

 true nephridia. But this is the first record of an earthworm in which two 

 pairs of nephridia occur regularly in each somite of the body. I Avill 

 not here eaater, in any detail, into the bearing which this arrangement 

 has on the theory of the genital ducts of earthworms being modified 

 nephridia: suffice it to say that I do not see any reason to regard it 

 as militating against Prof. Lankester's theory, if, instead of starting 

 with two pairs of nephridia, on each side, one of Avhich has disappeared 

 except in the somites in which they have become modified as genital 

 ducts, we take as the origin such an arrangement as obtains in many 

 Perichaetae — viz. numerous scattered tufts of tubules. This I am in- 

 clined to think is the primitive arrangement, from which the usual 

 condition has been derived by suppression of certain of the nephridia, 

 and a concomitant increase in size of the remaining ones : whilst some 

 of the primitive nephridia have, in certain somites taken the function 

 of genital ducts. 



Unfortunately we have no enibryological data on this point, the 

 latest writer on the development of the earthworm '^, although dealing 

 with the development of the nephridia, makes no mention of the geni- 

 tal ducts. 



London, Dec. 1887. 



III. Mittheilungen aus Museen, Instituten etc. 



1. Zoological Society of London. 



17*^ Januar}', 1SS8. — The Secretary read a report on the additions 

 that had been made to the Society's Menagerie during the month of December 

 1887, and called attention to a small Fox from Afghanistan, presented by 



3 Proc. Hoy. Soc. 1SS5. p. 459. Proc. Zool. Soc. 1885. p. 822. 

 * Beddard, Proc. Zool. Soc. 1S85. p. 822. 



5 Perrier, Arch, de Zool. Exp. t. II. 1873. 



6 Wilson, Journ. Morphol. Vol. I. 1887. 



