392 NOTES ON AUSTRALIAN EARTHWORMS, 



on to the succeeding segments as far back as the first dorsal pore. 

 It may then be present on all the succeeding segments of the body. 

 Thus the grooving may be absent from all the first six or seven 

 segments, or present on the first one and absent from the others 

 up to about the twelfth segment, but from this backwards it is 

 present in every one of the specimens, commencing at the dorsal 

 pore on the anterior margin of the segment and terminating at the 

 pore on its posterior margin, so that it may be said that all or the 

 greater part of the body is marked in the median dorsal line by a 

 longitudinal linear groove interrupted at the dorsal pores. In 

 addition all the specimens show a similar but shallower and fainter 

 median ventral grooving on the posterior half of the body, com- 

 mencing at a variable distance (in one case at segment xx) behind 

 the girdle. 



Segments in front of the girdle widest, usually bi-annulate. 



Setae on a conspicuous ridge just behind the annular groove, fre- 

 quently the ridge not limited by grooves ; a median dorsal and a 

 median ventral interval devoid of setje, the latter well-defined 

 throughout, its bounding rows of setse straight, between two and 

 three times the width of the interval between two setae, a little wider 

 anteriorly ; the dorsal interval at first very broad, sometimes but few 

 dorsal setse in this region, further back the interval is narrower, but 

 throughout owing to gaps in the half-circles of setae its bounding 

 lines are very irregular and sinuous : the first two or three seti- 

 gerous segments appear normally to have 16 setae per segment, the 

 next few 24, increasing shortly to 34, eventually increasing in the 

 most posterior segments to about 50 per segment. The details are 

 liable to considerable variation as not only arc there gaps in the 

 half-circles of setae, but especially in the anterior dorsal region 

 portions of the setigerous ridges disappear leaving the surface quite 

 smooth ; so that in a genei'al way the pre-clitellar segments may 

 be said to have any number of setae from 14 to 38, though after 

 the first few the number 24 sometimes occurs pretty regularly ; 

 sometimes more setae are visible on one side of a segment than on 

 the other. 



