58 FAMILIES OF EARTHWORMS. [CH. I 



regard to the problems afforded by geographical distribu- 

 tion is the entire absence of any knowledge whatsoever 

 about extinct forms. We cannot therefore compare the 

 past with the present. 



Earthworms are divisible into seven families : Crypto- 

 drilida?, Pericha3tidae, Acanthodrilidae, Eudrilidge, Geo- 

 scolicidse, Moniligastridae, and Lumbricidse. Of these the 

 first three are very nearly related and may be united into 

 one super-family Megascolicida^, which possibly is really 

 equivalent to any of the other families Eudrilidae &c. 



The Cryptodrilidse are world-wide, but most abundant 

 in the Australian region and in South America. The 

 Pericha?tida3 are chiefly Australian and Oriental, but 

 occur in the Neotropical and Ethiopian regions. The 

 Acanthodrilidas are mainly massed in New Zealand, 

 South America, and Africa ; they are also found, though 

 rarely, in Australia, Malaya and North America. The 

 Eudrilidae are absolutely confined to Tropical Africa, 

 the Geoscolicidjje to Tropical South America, Tropical and 

 Southern Africa, just reaching Europe and Malaya. The 

 Lurnbricidse are probably only indigenous in the Nearctic 

 and Palaaarctic regions. 



But it is necessary to go into further details to bring 

 out the salient facts in the distribution of the Oligocha3ta. 



The list, which I shall now give, is freed from obvious 

 importations like the Lumbricidse of exotic range dealt 

 with elsewhere. The same kind of argument removes 

 the Perichaetida3 from the Nearctic and Palsearctic 

 regions. Two genera belonging respectively to the Geo- 

 scolicidse and Eudrilidse, viz. Pontoscolex and Eudrilus are 



