68 RANGE OF CRYPTODRILIO&:. [CH. I 



is marked out from all others by the fact that the ovaries 

 are nearly always contained in special sacs, which are 

 developed at the expense of the septa, and whose cavities 

 therefore are true body cavities; and that these sacs 

 communicate with the exterior by the oviducts or by 

 special orifices or by both. In several genera the neph- 

 ridia, which are, as in the Lumbricidae, paired structures, 

 a pair to each segment of the body, branch copiously in 

 the thickness of the body wall, opening on to the exterior 

 by many pores in a single segment. There are other 

 peculiarities of structure which mark out the Eudrilidse 

 as one of the most isolated of families and therefore the 

 Ethiopian region as, from the point of view of its earthworm 

 inhabitants, one of the most peculiar of regions. It is 

 noteworthy, seeing that recently many of the West African 

 animals — for example the Chimpanzees — have been shown 

 to extend into East Africa, that the genera of earthworms 

 belonging to this family are not common to both sides of 

 the continent. We have on the west coast the genera 

 Heliodrilus, Rypriodrilus and Lybiodrilus among others ; 

 on the east coast Stuhknannia, Polytoreutus, Eudriloides 

 and Notykus, &c. &c. 



. The family Cryptodrilidse is as has been already re- 

 marked nearly cosmopolitan. But the various genera, of 

 which the family is made up are none of them of so wide 

 a range. Most of the principal regions have their peculiar 

 genera ; but the South American forms range also into New 

 Zealand. These species belong to the genus Microscolex 

 which occupies pretty nearly the whole of the South 

 American continent and the warmer parts of the Nearctic 



