CH. Ill] ACANTHODRILUS. 169 



tions from that part of the world do not so frequently as 

 formerly contain new species. This fauna consists prin- 

 cipally of species of the genus Acanthodrilus. There are 

 three genera of the same family peculiar to New Zealand, 

 viz. Octochcetus, Plagiochceta and Deinodrilus. All these 

 worms form a very well-marked family which is character- 

 ised by the fact that the male sperm ducts open on to the 

 xvinth segment of the body, and that on to the two seg- 

 ments in front of and behind this open a pair of coiled 

 tubular glands accompanied by a bundle of modified 

 " penial " setae. The bulk of the species of Acanthodrilida? 

 belong to the genus Acanthodrilus itself. Besides this 

 genus there are three species of quite a different genus, 

 Microscolex. This genus is referable to another family 

 allied however to the Acanthodrilidae. There is here only 

 one pair of tubular glands which open in common with or 

 or very close to the sperm ducts upon segment xvn. The 

 penial setae also exist. The remaining Oligochceta tern- 

 coke of New Zealand, apart from introduced Lumbricidcv, 

 are a few species of Perichceta, or rather a closely allied 

 genus which I have named Diporochceta. In the more 

 southern parts of the South American continent precisely 

 the same families are met with ; and not only that, but 

 the same genera. Dr Michaelsen of Hamburg has recently 

 made a voyage to that part of the world, and has brought 

 back with him a very large collection of earthworms; 

 these belong, with the exception of introduced Lumbricidcv 

 and a single Perichcvta, exclusively to the genera Micro- 

 scolex, Acanthodrilus and Kerria (a near ally of Acantho- 

 drilus). So far as we know at present not a single species 



