424 W1LHEL1\1 MICRAELSEX. 



the median ventral distance diminishes^ while the median 

 dorsal distance is enlarged. The degree of this dislocation 

 of the lines of sette varies somewhat in different specimens, 

 and may depend on the state of contraction of the body. 



The ventral setas of the fifteenth to twenty-first segments are 

 transformed into sexual setee and are not as strictly paired as 

 in the case of the normal setae. In some specimens the median 

 ventral distance of setas is hardly larger than twice the 

 distance of the seta3 of a ventral pair : aa = 24- - 3 aJi at 

 segments 15 to 21. 



Nephridial pores are in the lines of setae c. 



Clitellum is saddle-shaped, and in all specimens extends 

 over ten segments, thirteenth to the twenty-second inclusive. 



Copulatory Organs. — At each side there is a very broad 

 and flat copulatory ridge ("Pubertatswall") extendingover four 

 segments, fifteenth to eighteenth, and ventrally nearly reaching 

 the line of setas J), while dorsally it reaches the middle lateral 

 line, transgressing considerably the line of the setae d and of 

 the nephridial pores, which line is bent ventrally in the 

 i^egion of the clitellum. The nephridial pores are seen 

 distinctly on the copulatory wall. The fore-part of this 

 copulatory wall belonging to the fifteenth segment is some- 

 Avhat differentiated, being thicker than the other parts, and, 

 especially laterally, it overhangs the borders of this segment. 

 In two of the specimens it looks like a narrow, laterally 

 rounded shield. From the fifteenth to the twenty-first 

 segment the ventral borders of the clitellum are formed by a 

 more or less distinct undulating white line. Between these 

 lines the body-wall is glandular and bears the sexual setae. 

 Only a very narrow medio-ventral strip of the body-wall is 

 free from this glandular modification. 



The male pores are in the middle of the copulatory walls 

 in the furrows between the sixteenth and seventeenth 

 seo-ments and somewhat beneath the lines of setge c and of 



o 



the nephridial pores. 



Female pores are somewhat medial to the lines of sette a in 

 front of the zone of seta) of the fourteenth segment. 



