152 OLIGOCHAETA 



It will be seen from the tables tbat the Neotropical and Ethiopian regions are 

 richest in genera, and that they are at the same time richest in genera peculiar to 

 each of them, and found nowhere else. The Ethiopian region is the richest in both ; 

 and this fact gets additional weight from the consideration that Africa has been, perhaps, 

 less explored than America and the West Indies from the present point of view. 



The Oriental and Australian regions are nearly equal to each other, both in the 

 number of genera and in the number of peculiar genera, and both of them are some 

 way behind the Neotropical region in both respects. 



Then comes the Palaearctic region and finally the Nearctic. 



The above tables are too accurate in one respect to bring out the essential 

 characters of the earthworm fauna of the different regions. In the Oriental region, 

 for instance, Moniliganter and Perionyx are very characteristic forms, and are both 

 represented by a number of species. If it were not for a single Moniligaster 

 (M. bahamensis) in the Bahamas, and a single Perionyx (P. sansibaricus) in the 

 Ethiopian region, these two genera would be absolutely limited to the Oriental 

 region. In the same way Cryptodrilus is confined to Australia, excepting for two 

 doubtful instances. One of these is Cryptodrilus spatulifer, which, as I point out 

 (below), is really perhaps in strictness not referable to that genus. The other 

 exception is a Cryptodrilid, which I received myself some years ago from India, but 

 whose identity with Cryptodrilus I should not like to positively assert. 



JtJegascolex ought really to be struck out of the list of Ethiopian earthworms, as 

 it only just gets into that region with one species (Perichaeta madagascariensis = 

 Megascolex armatus) in Madagascar. So, too, as already remarked, Perionyx. 



The following list indicates the characteristic genera of the several regions ; those 

 which are abundant in individuals or species, or both, or are absolutely confined to 

 the region in question, though not abundant. 



Neotropical. 



j. Geoscolex. 6. Urobenus. n. Trigaster. 



2. Rhinodrilus. 7. Tykonus. 12. Benhamia. 



3. Anteus. 8. Trichochaeta 13. Kerria. 



4. Diachaeta. 9. Perichaeta. 14. Gordiodrilus. 



5. Onychochaeta. 10. Acanthodrilus. 15. Microscolex. 



Oriental. 



1. Moniligaster. 3. Annadrilus. 5. Deodrilus. 



2. Glyphidrilus. 4. Typhoeus. 6. Microdrilus. 



