332 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Instead of passing out at right angles to the dorsal vessel, 

 as is the rule, they have a somewhat more forward 

 direction and may extend into the segment in front, the 

 septum between segments 1 and 2 being absent (PI. VI, 

 fig. 41, pv. v. 2). They become slightly coiled, and then 

 dip down to open into the ventral vessel a short distance 

 behind their origin from the dorsal vessel. 



The perivisceral vessels of segments 3-7 have a similar 

 distribution to that described above for segment 2, but in 

 segments 4-7 they lie entirely in the segment to which they 

 properly belong, owing to the presence of septa between 

 adjacent segments, thus preventing the passage of the 

 vessels from one segment to the other. It should be noted 

 also that the right and left perivisceral of segments 2 

 and 3 open into the right and left branches of the ventral 

 vessel respectively. 



In segment 8 the perivisceral vessels are absent. 

 In segments 9 and 10 they become coiled around the 

 anterior and posterior sperm sacs respectively. In 

 segments 11-17 of a mature worm which contain the 

 ovisac the perivisceral are always coiled around this 

 organ. In all the segments behind those containing the 

 reproductive organs these vessels pass simply from the 

 dorsal to the ventral vessel. 



The "hearts" are situated in segment 8. They 

 originate from the supra-intestinal vessel above, in the 

 posterior part of the segment, and open into the ventral 

 vessel below (PL I, fig. 2, ht.). They are much enlarged, 

 especially near their origin from the supra-intestinal 

 trunk, and are contractile. 



The blood is a red, non-corpusculated fluid, the 

 haemoglobin being dissolved in the blood plasma. 



