1018 NOTES ON AUSTRALIAN EARTHWORMS, 



rows being more exposed to wear and tear than the ventral ones 

 seems to be attributable to a tendency to a reduction in the number 

 of setae commencing with those in the dorsal region, as the ventral 

 setae and especially the first and second of each half series are 

 remarkably constant in their presence even on segment ii, on 

 which sometimes the total number visible is only three or four. 



The ventral interval devoid of setse is very well marked through- 

 out, but anteriorly where the setse are fewer and further apart, 

 and as elsewhere, not always at equal distances apart even on the 

 same segment, its width may be much less than that of an ordinary 

 interval between two setse. The dorsal interval is narrower. 



In mature worms in which the ventral surface of xviii is more 

 or less modified the first visible seta on each side is usually the 

 third or fourth (counting from the ventral ends of the half-series); 

 in an immature specimen on which the surface of this segment is 

 unmodified and the ^ pores quite distinct the first two on each 

 side are wanting or invisible, and the pores are seen to be in what 

 would be the interval between the second and third setae but a 

 little dorsad of the position of the first setre ; from the unequal 

 distances between the setse, or from the third or fourth setae being 

 hidden by the tumidity of the ventral surface, one is often obliged 

 to judge of their position by that of the setae on the preceding or 

 succeeding segment, and then the pores sometimes seem to corres- 

 pond with the interval between the third and fourth setae. The 

 oviduct pore is single and median (not two pores as previously 

 stated) ; owing to the irregularity of the setae the spermathecal 

 pores are sometimes opposite the intervals between the fourth and 

 fifth or more usually the fifth and sixth setae. 



Dorsal pores commence after segment iv. 



In mature worms the tissue round the male pores becomes 

 modified, or they are surrounded by a tumidity connecting the 

 accessory copulatory papillae of the second and third padrs on each 

 side. 



Genitalia: two pairs of testes and two pairs of ciliated rosettes 

 in X and xi ; three pairs of vesiculae in xi-xiii (in xiv there may 



