Australian Eartliwoinns. 67 



7. — Perichaeta macquariensis, Fletcher. Proc. Linn. hsoc. 

 N.8.\V., vol. iv., 18c^9. 



Megascolex macquapiehsis, Fletcher. 

 Plate XV., Pig. 7. 



Dissection. — Dorsal vessel single and swollen in segments 

 10-18, running forward to break up in the first segment. 



The ventral also is single, and breaks up in the first segment, 

 giving off marked branches to the ventral body wall in seg- 

 ments 5, 6. 7, 8 and 9, and receiving in these segments a 

 commissural vessel from the dorsal. Commissurals also arise 

 from the dorsal from segment 13 backwards. That in 4: does 

 not reach the ventral, but divides into two, one running forward 

 to segment 1, and the other back as the lateral in 5-9, and as 

 the sub-intestinal in 10. 11 and 12 in the last of which it ends. 

 In these last three it gives off vessels ending on the posterior 

 septum of the segment. Bourne (11) also remarks that in M. 

 ■coertdeiis the anterior of bis lateral hearts do not reach the 

 ventral vessel, but give off branches to connect with the intes- 

 tino-tegumentary system, 



A supra-intestinal arises from the dorsal vessel posteriorly 

 in segment 12, and runs forward to the front of 10, givincr off 

 in 10, 11 and 12, in the hinder part of the segment, a pair of 

 hearts, which pass to the ventral vessel, and also from this 

 vessel branches arise which supply the alimentary canal and 

 join the sub-intestinal. * 



8. - Perichaeta valida, Kletcher. 

 Plate X\'., Fig. 8. 



Dissection. — Single dorsal vessel, swollen in segments 13-16, 

 less so in 12-9. From 13 backwards it gives off a conuaissural 

 vessel in each segment, supplying the alimentary canal on the 

 way, and this arrangement is continued tu segn^eut 13 in 

 which there is no connection between the dorsal and ventral. 

 These latter both run forward, breaking up and apparently 

 joining in segment 1, and the dorsal gives off a supra-intestinal 

 ill the hinder ])jirt of 13, which runs forward to the front of 7. 

 Commissural vessels arise from the dorsal in 9-4:. and reach 



