406 WJLHELM MICHAKLSEN. 



invaded South Africa from the northern regions in past 

 geological time, yet its presence forms the sharpest contrast 

 between the modern oligocheete fauna of South Africa and 

 that of tropical Africa. The latter is dominated by the 

 phyletically much younger groups of the Trigastrine genus 

 Dichogaster and the sub-family Eudrilina?. These are 

 living in South Africa with the Ocnerodrilinse and with 

 some other aquatic and amphibial groups. The Ocnero- 

 drilinas have only a portion of their dominion in this region, 

 and they stand somewhat apart owing to their different habitat. 



To recapitulate, the endemic fauna of the Oligochgeta of 

 Natal and Zululand proves to be an integral portion of the 

 Cape fauna with a small addition of outposts from the 

 tropical African fauna. 



But the oligochtete fauna of the Cape region is not homo- 

 geneous, the Microchastinte prevail in the eastern districts, 

 whilst the Chilotacea occur especially in the western parts. 

 In this respect Natal and Zululand seem to even surpass the 

 south-eastern districts of the Cape Province. 



The faunistic character of the numerical preponderance of 

 Microchretus over Chi lota is accompanied by a peculiarly 

 local distribution. All Microchfetus species are found in 

 very restricted areas of Natal and Zululand, although they are 

 true endemic species. Somewhat different is the distribution of 

 the Chilota species. It is true that Ch. warreni has up till 

 now been found only in Natal, but the three other species have 

 a much wider distribution: Ch. tragardhi occurs both in 

 Natal and Zululand, Ch. wahlbergi in Natal and the 

 Transvaal, and Ch. braunsi in Natal and the Cape. These 

 species may be regarded as peregrine to a certain extent, 

 since probably they invaded Natal and Zululand at a fairly 

 recent geological period; but the Microcha3tus species are 

 the real aborigines of the eastern parts of South Africa. 



The eastern fauna of the Cape is distinguished from the 

 western by the non-occurrence of certain genera. The 

 genera in question both belong to the section Acanthodri- 

 lacea [Eodrilacea] of the sub-family Acanthodrilinas. 



