624 OLIGOCHAETA 



This family of Oligochaeta contains a considerable number of well-marked genera ; 

 with the exception of the genera Hormogaster and Criodrilus, they are all inhabitants 

 of the Tropics both of the Old and New Worlds. TJie following are the genera which 

 have been at present fully characterized: — 



(i) Pontoscolex ( = Uroehaeta, E. P.), ScHMAEDA. 



(a) Diaohaeta, Benham. 



(3) Onychoehaeta, F. E. B. 



(4) Triehoehaeta, F. E. B. 



(5) Geoscolex ( = Titanus, E. P.), F. S. Lbuckakt. 



(6) Anteus, E. P. 



(7) Mierochaeta (E. P.), F. E. B. 



(8) Rhinodrilus ( =r Thamnodrilus, F. E. B.), E, P. 



(9) TJrobemis, Benham. 



(10) Brachydrilus, Benham. 



(11) Hormogaster, Rosa. 



(12) Glyphidrilus, HOKST. 



(13) Callidrilua, Michaelsen. 



(14) Kynotus, MiCHAELSEN. 



(15) Bilimba, RosA. ' 



(16) Tykonus, Michaelsen. 



(17) Ilyogenia, F. E. B. 



(18) Annadrilus, HoEST. 



(19) Sparganophilus, BenhAm. 

 (ao) Siphonogaster, Levinse*. 



In addition to these genera, of which adequate descriptions exist, there are a few 

 of the worms so imperfectly described by Kinbeeg, which may possibly belong to the 

 same family. These are : — 



Tritogenia. 

 Geogenia. 



The most aberrant type is undoubtedly Hormogaster; this genus has been 

 recently studied by Rosa, who has pointed out several characters which it shares 

 with the Lumbricidae. The most marked of these is perhaps the position of the 

 male reproductive pores ; these pores lie, in the genus under consideration, in the 

 groove separating segments xv and xvi ; so far^ there is a resemblance to the 

 Lumbricidae ; there is a further likeness to the genera of that family in the fact 

 that the spermathecae are in segments x, xi, and xii ; in his first note (32) upon 



