v] RELATIVE FREQUENCY 77 



is mainly found in Africa, the rest being found in the 

 neighbouring Madagascar and some few in the East. 

 Microchaetus contains about 14 species, Trltogenia 

 perhaps three, Callidrilus two, and the genus Glyphi- 

 drilus, mainly found in Asia, has one species in the 

 region now under consideration. In addition to these 

 Geoscolecids there is the peculiar and largely aquatic 

 Alma with six or seven species in East, West, and 

 Central, Africa, and in the Nile region. 



Summing up the genera which are found in 

 tropical and South Africa we find that there are 44 

 which are abundant in, or entirely confined to, the 

 region. In addition to these four or so occur in 

 Africa but are either more abundant elsewhere or 

 (as in the case of Chilota and Notiodriliis) are equally 

 distinctive of other parts of the world. The number 

 of species may be estimated at 270, possibly rather 

 more. Clearly therefore this part of the world is 

 much richer than South America, both in numbers 

 of genera actually found, and peculiar to the country, 

 and numbers of species. 



Passing from Africa the next definite quarter of 

 the globe which will detain us here is the island of 

 Madagascar, so remarkable for the Mammalian fauna 

 which characterises it, for its lemurs, peculiar Insec- 

 tivora and Carnivora, and above all by reason of the 

 absence of the prevalent African types such as 

 antelopes, zebras, rhinoceros etc. It is probable 



