The Classification and Distrilnition of Earthworms. 287 



It is an old form, and has, therefore, had time to spread 

 widely, like the tapir and Feripattcs. 



But although the resemblance may have something to do 

 with climatal causes, the evidence at our disposal by no 

 means supports any theory of climatal distribution and 

 division of the world into faunal zones. 



The Australian region, at any rate as regards the Australian 

 continent, has a somewhat peculiar earthworm fauna. Apart 

 from Pcrichmta and Megascolex, which occur here as in almost 

 all parts of the world, there is the peculiar genus Anisochceta, 

 which connects Pcrichmta with Cryptodrilus} This latter 

 genus is, with the exception of two species, confined to 

 Australia. It and Mcgascolides, Digastcr, and Didymogaster? 

 which are absolutely confined to Australia, are the most 

 characteristic genera of that continent. Urochceta is repre- 

 sented in Queensland by a distinct species.^ Acanthodrilus 

 is represented by one species, as is also Microscolex (Rosa 

 considers that Fletcher's Eudrilus ditbius is probably really 

 to be referred to that genus). The bulk of the Australian 

 earthworms therefore belong to Rosa's family Eudrilidce 

 (which, as it appears to me, is a very natural family, if 

 only Eudrilus itself be excluded !). Out of the remaining 

 eight genera of this family, three — viz., Neodrilus, Bhodo- 

 drilus, and Dichogaster — are confined to the Australian 

 resjion, thoug;h not inhabiting Australia itself. Of the 

 remaining five, Pontodrilus and Photodrilus are Palsearctic, 

 while Typhmus is Oriental, in fact, Indian, and Eudriloides 

 and Callidrilus are Ethiopian. 



The Australian area, especially the Australian continent, 

 forms, therefore, a very well-marked distributional region, 

 which has something — though little — in common with the 

 Oriental region. 



Oceanic islands are naturally — from their origin — not 



1 I regard Michaelsen's Cryptodrilns purpure^cs ( = unicus, Fl. ) as represent- 

 ing a new genus. I discuss the reasons for this in a forthcoming paper. 



^ Fletcher's Ferissogaster does not appear to me to be a valid genus. 



2 I hope to show elsewhere that some examples of Urochceta, which I 

 described from Queensland some years ago (Observations on the Structural 

 Characters of certain new or little known Earthworms — Proc. Roy. Soc. Edin., 

 vol. xiv., 1887, p. 160 et seq.), are distinct from U. cordhrura. 



