V] RELATIVE FREQUENCY 73 



of which two at least are found elsewhere, and of 

 which therefore the autochthonism is doubtful. 



Finally, there is the sub-family Ocnerodrilinae 

 comprising the following genera : Kerria with ten 

 species, Ocnerodrilus (with sub-genera Liodrilus, 

 Ilyogenia and Haplodrilus) four species, which again 

 are rather doubtful indigenes of the South American 

 Continent. 



Leaving aside certain species (of the genera 

 Lumbricus, Pheretima, etc.) which are clearly not 

 indigenous, the South Auierican Continent harbours 

 150 kinds of earthworms which are distributed in 

 some 19 genera. But of these a few species {e.g. 

 Onychocliaetawimllel, Kerria macdonaldi) stray into 

 neighbouring regions, i.e. the West Indies and Cali- 

 fornia. It is doubtful therefore whether they are to 

 be referred to as limited to one of these regions and 

 accidentally imported into the others, or whether they 

 are genuine inhabitants of both. 



The South American Continent sliares with the 

 West Indies the following genera, but the species 

 (except in the case of Ottt/chochaefa iriudhl, Glof^so- 

 scolex percgrinu.s) are distinct ; these genera are 

 HeH2M7'oscolex, Pontoscole.r, Dichogaster, and Ocnero- 

 drilus. Diachaeta is limited to tlie West Indies. 



The following South American genera arc also 

 found in Central and warmer North America 

 (Mexico, California), viz. Hesperoscolex, Periscolex, 



