66 EARTHWORMS OF NEW ZEALAND. [CH. I 



segment. Acanthodrilus has the usual paired series of 

 nephridia. Kerria is a genus which is absolutely re- 

 stricted to America; it is noteworthy on account of the 

 fact that it shows in several particulars evidence of 

 degeneration. Thus there is only a single pair of cal- 

 ciferous glands in the ninth segment, a character which 

 it shares with several of the more simplified genera of 

 Cryptodrilidae, such as Qordiodrilus ; the tubular glands 

 which open in common with the sperm duct are lined by 

 a single layer of cells instead of the thick layers so closely 

 resembling those of the clitellum which are found in the 

 majority of the remaining genera of earthworms. 



The three genera Octochcetus, Deinodrilus and Plagio- 

 chceta are absolutely limited in range to New Zealand, 

 which may be considered to be the head-quarters of the 

 family, as it also possesses a fair share of the known 

 species of Acanthodrilus. Only three species of the latter 

 genus are found in Australia, and it is a noteworthy fact 

 that these three exist in Queensland and the neighbourhood 

 of Torres' Straits, on the side in fact which is turned towards 

 New Zealand and which has been probably at one time, 

 no doubt remote, joined to New Zealand. The remaining 

 species of Acanthodrilus are with a very few exceptions 

 inhabitants of the more southern regions of the South 

 American continent. They abound in Patagonia; but 

 they do not, on the east side of that continent, get 

 further north than Montevideo; on the other hand in 

 Chili the genus extends considerably further north. The 

 exceptions that have just been referred to relate to 

 Kerguelen, Marion Island, the Cape of Good Hope, and 



