STRUCTURE OF EARTHWORM ALLIED TO NEMERTODRTLUS. 553 



was prolonged backwards and downwards to the neighbour- 

 hood of the ventral vessel ; this branch (a) does not, however, 

 open into that vessel, but runs into one of the muscular bands 

 which unite the cEsophagus with the parietes. Farther back 

 still each vessel gives off a branch which supplies the inter- 

 segmental septum ; here its capillaries no doubt unite with 

 those of branches of the ventral blood-vessel. In the 10th 

 segment there was no connection between the two sub-ceso- 

 phageal trunks ; each of them gives off a branch {a) which 

 supplies the muscle (m.) running from the oesophagus to the 

 parietes. 



These branches pass along the walls of the perihaemal space 

 and reach the interior of the muscle, along which they pass to 

 its point of insertion ; these two branches, of course, cor- 

 respond to the single cutaneous branch which I have described 

 in Segment 9. At the septum dividing this segment from the 

 11th a branch is given off from each vessel, which supplies not 

 only the septum but also the sperm-sac. In the next segment 

 the branches of the sub-oesophageal vessels are the same, and 

 therefore need no description. I imagine that these sub- 

 oesophageal vessels represent, wholly or in part, the lateral 

 trunks^ of other earthworms, which appear at least frequently, 

 if not always, to take their origin from the peri-oesophageal 

 blood network. 



§ Nephridia. 



In dissecting the worm the nephridia were quite obvious in 

 most of the segments of the body ; and where visible, pre- 

 sented a paired arrangement which characterises all the 

 Eudrilidse. In the posterior region of the body the nephridia 

 were particularly conspicuous, both in fresh and alcoholic 

 specimens, by reason of their opaque white coloration. In 

 the anterior segments of the body the nephridia were largely 

 adherent to the posterior septum of their segments, and did 

 not show the white opaque appearance of the posterior 

 nephridia. We have evidently here another instance of what 

 ' " Intestino-tegumentary." 



