450 WJLHELM MICHAELSBN. 



6 b. Outermost pairs of setse in the lateral middle lines or 



even above tliem ; median dorsal distance of seta? 

 equals one-lialf of the whole circumference of the body 

 or even smaller. ..••■' 



7 n. The median ventral distance between the innermost ventral 



seta; diminishes distinctly towards the copnlatory walls, 

 whieli occur on the fifteenth to eighteenth segments. 



Microchffitus natalensis {Kiiib.) 



7 b. The median ventral distance lietween the innermost ventral 



setse does not diminish distinctly towards the copnlatory 



walls. ..■■■• ^ 



8 a. Copnlatory walls extend over the whole length of the 



clitellum, twelfth to twenty-third or twenty-fourth seg- 

 ments. . . . Microchsetus beddardi Be)ih. 



8 b. Copnlatory walls occupy only a part of the length of the 



clitellum, less than half of it. . • .9 



9 a. Copnlatory walls occupy more than four segments. . 10 



9 b. Copnlatory walls occupy four segments or fewer. . 11 



10 a Number of segments in mature specimens larger than 



oO(». Copnlatory walls stretch over segments 16-20, 

 and are prominent laterally. Microch^tus papiliatus 



Benh. 

 a Clitellum extends from the tenth to the twenty- 

 ninth or thirtieth segment; copxilatory cushions 

 indistinct. . '• • f . typicus 



/3 Clitellum extends from the twelfth to the twenty- 

 fourth segment : distinct copnlatory cushions 

 stretch over segments 17-20 . var. csementerii ». var. 



10 b. The number of segments in matin-e specimens is smaller 



than 150. Coj)ulatory walls extend over the sixteenth 

 (or part of it) to the end of th.e twenty-second segment, 

 not prominent laterally. . Microcha^tns zuluensis 5efZd.. 



11 «. Copnlatory walls occupy the three segments from the 



seventeenth to the nineteenth. . . .12 



11 b. Copnlatory walls are prominent cm the sixteenth and 



seventeenth segments, indistinct on the eighteenth 

 segment, and hardly recognisable on the fifteenth seg- 

 ment. . . . Microchsetus parvus n. sp. 



12 a. Copnlatory walls are upon the median slope of a lateral 



projection occupying segments 17-19, or they may 

 extend over the neighbouring segments 16 and 20. . 13 



12 b. Copnlatory walls are on the flat ventral side of the body, 

 tliere being no lateral projections. 



Microchsetus colletti Bedd. 



