THE OLIGOCH.^;rA OF NATAL AND ZULULAND. 405 



{'S) Sub-fam. Mic'rocluetina3.— This sub-fciniily, beloiig- 

 iiig to the family Glossoscolecidge, forms with its nine 

 species of the genus Microchfetus the bulk of the original 

 indigenous oligochfete fauna of Natal and Zululand. The 

 genus Microcli^tus is strictly confined to South Africa, 

 and is distributed throughout the whole of the Cape 

 Province, but it is more prevalent in the eastern (and 

 northern ?) districts. It passes norihwards as far as the 

 north-west corner of the Cape Province, also to the northern 

 frontier of the Orange Free State and to Zululand. 



The nearest terricolous ally of this genus is Kynotus of 

 Madagascar ; but the relationship is not very close, and inter- 

 mediate steps are exhibited by certain aquatic forms. The 

 genus MicrochtBtus was doubtless derived from the aquatic 

 genus Glyph idrilus, whilst the aquatic genus Callidrilus 

 must be regarded as the ancestor of Kynotus. Both of 

 these aquatic ancestors are living in the enstern parts of 

 ti'opical Africa. Glyphidrilus also occurs in the P^ast 

 Indies and in the Malay Archipelago. In the regions of 

 their presumed descendants these genera have not been 

 found, neither Callidriliis in Madagascar nor Glyphi- 

 drilus in South Africa. 



It is doubtful in what region the terricolous genera 

 Microcha3tus and Kynotus have arisen. They may have 

 originally developed from their aquatic ancestors in eastern 

 tropical Africa, and have spread from there to the southern 

 regions, becoming extinct in the land of their birth. On the 

 other hand, we might assume that their ancestors in former 

 times had a wider distribution, Glyphidrilus extending 

 over South Africa and Callidrilus over Madagascar, and 

 that they have become extinct after giving rise to their 

 terricolous descendants. 



Be this as it may, the time of the descent of Mici-o- 

 cha^tus and its allies from their aquatic ancestors must be 

 placed in a far-distant geological period; and we must regard 

 the genus Microcha9tus as typically South African. 



Even if we have to assume that the genus originally 



