Camerox. — Xepltridl iini of Madiidrihis lo.sae Bcddard . 173 



In 1894 new t;roiind was opened by Eisen (16), who gives very 

 elaborate figures of the nephridium of PJutelhis (Argilophihis) inarwnratus. 



In 1895 appeared Beddard's " Monograph of the Order Oligoc/iaetn '" (7), 

 m which there is a resume of all that was known, and of the various specula- 

 tions that had been put forward, in connection with nephridia. 



In the same year Bourne published his account (15) of the anatomy 

 of Monilujaster grandis, and described in detail the structure of the ne- 

 phridium, so that another family of earthworms was now included in the 

 list. In it there is a branching of the fine canal, forming "ductlets,'" which 

 anastomose and form a network recalling that in Microchaeta. 



In 18i^5 Eisen extended our knowledge by his account (17) of the ex- 

 cretory orgaii in Ocnerodrilns (Phoeiiicodrilus) taste, Kerria macdonaldi, and 

 Pontodrilvs inic/HieIseiii : and in 1896 he described (18) it in detail for Didy- 

 inogaster (BeiiJidiiiia) iKiiia and Dlplnrardia (AleodriJus) keyesi. membei'S 

 of the Megascolecidae. 



We now have information as to the minute structure of this organ and 

 of the couise of the canal in the following families and Subfamilies :— 



MoNiLiaASTERiDAE, by Bourne. 



MEGASCOLEdDAE. 



Subfaiu. AcdnthodiiVnidc. In the present paper : also, Benham, 

 Beddard. 

 ,, Megascolecinae. Kiaen, in Poiitodrilus. Didyiiiogastei\ Spencer, 



Megascolecides, &c. 

 ,, OctocJiaetinae. Beddard, in Octochaetus. 

 ,, Diplocardiinae. Eisen, in Diplocardia. 

 ,, Trigastrinae. Eisen, in Dichogaster. 



Ocnerodrilinae. Eisen, in Kerria, Ocnerodrilus. 

 Glossoscolecidae. 



Subfam. (rlossoscoleeiitae. Eisen, Pontoscolex. 



,, Micrnchaetivae. Benham, in MicmcJ/aeta. 



LUMBRICIDAE. 



Lumbiieiis. &c. 







The present contribution deals with the Acanthodriline worms, of which 

 hitherto no detailed account has Tjeen pulilished. 



As a result of a comparison of these various genera, we may state, in 

 general terms, that there is a fundamental similarity in the structure and 

 arrangement of the canals in the nephridium of the various families of 

 worms belonging to the " Megadrilous " group of OUgochaeta, known as 

 earthworms. 



Apart from the above-mentioned accounts of minute anatomy, it is 

 needless to say that the general structure of the nephridium, the disposi- 

 tion of the loops or coils, their relation to the bladder, the forn\ of the funnel, 

 and so fortli, have been described and figui'ed for many other species. 



The Nephridium op Maoridrilus rosae. 



The microscopic structure of the native earthworms of New Zealand is 

 but very slightly known. I therefore decided to undertake, as a beginning, 

 a detailed study of the nephridium. and have used this species for the 

 purpose as it is a very common worm in certain parts of the Dominion, 

 aud an abundant supply can be obtained. 



