312 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



The setae are arranged in four bundles in every 

 segment of the body except the first and the last. Two 

 of these bundles are ventral in position, and lie one on 

 either side of the mid-ventral line. These are spoken of 

 as the ventral bundles (PL III, fig. 11, v.bl.). The other 

 two are much more dorsal in position, and are referred to 

 as the dorsal bundles (fig. 11, d.bl.). 



Three kinds of setae are present, viz., capilliform, 

 uncinate, and pectinate (PL II, fig. 6). The distribution 

 of the capilliform setae is limited, for they are confined 

 to the dorsal bundles, and do not usually extend further 

 back than the 30th segment. The uncinate setae are 

 common to both dorsal and ventral bundles throughout 

 the body, while the pectinate form is limited to the 

 dorsal bundles of the anterior segments, and is absent 

 from some of these. 



The capilliform setae are long, straight, hair-like 

 in form, and narrowing to an extremely fine point at the 

 free end (PL II, fig. 6, d). By far the greater part of 

 the seta is exposed, only about a quarter of it being 

 embedded in the setigerous sac. These setae are quite 

 smooth and devoid of barbs, such as are described by 

 Beddard (1895) as occurring in Lophochaeta ignota. The 

 longest ones occur in segments 6 to 9; behind the latter 

 segment they become smaller and smaller, until, at last, 

 they completely disappear. It is very unusual for there 

 to be more than three capilliform setae in a bundle, and 

 very commonly only one or two are present. In those 

 cases where three setae are present, they vary consider- 

 ably in length, and as a rule two of them are long while 

 one is much shorter. 



Beddard (1895), in his classification of the setae of 

 Oligochaeta, divides them into two main groups: — 



(a) Long, slender setae gradually diminishing in 

 diameter towards the pointed extremity — capilliform. 



