306 



Jean, Shannon: 



and an internal longitudinal clear region, that may, perhaps,, 

 indicate the presence of a minute duct. Along the latter- 

 at intervals are rounded patches of very numerous and clearly 

 nucleated cells. The rest of the structure seems to be almost non- 

 cellular. Sometimes the base of the '* head " is distinctly broad- 

 ened, and a number of parallel ducts appear to traverse it. In; 

 yet other cases the central duct seems to follow a spiral course. In 

 one instance the end of the structure appeared to bend towards 

 an opening through the septum, thus seeming to indicate a rela- 

 tionship to the successive segments typical of meganephridia. 

 (Plate XXIX. Fig. 4.) 



The supposition that these organs are connected with the excre- 

 tary function is further borne out by the development as seen in 

 very young specimens. At an early stage the whole structure is 

 hardly more than a cliain of cells, with large nuclei, and at inter- 

 vals clusters of even more regular and oblong cells. An. 

 arrangement that suggests the nephridial structure in some species 

 of Megascolides figured by Beddard, page 51, fig. 13. 



The marked similarities between this worm and certain of the- 

 Megascolides^ types again strengthens th^ idea that the mega 

 nephridia which are generally well developed in the latter genus are 

 represented in this animal by the peculiar structures described 

 above. Besides this, tlie position of the organs at the posterior 

 end, their segmental arrangement, and their structure also bears 

 out the theory as to their function. 



Blood Vascular System. 



This system is very difficult to study, except in freshly killed 

 specimens. Extending along the mid-dorsal line of the main length 

 of the body is a large thin-walled dorsal vessel. Smaller lateral 

 vessels are given off on each side in segments five, two and nine. 



Just ventral to this vessel is a much smaller median one, extend- 

 ing between segments eight and fourteen. 



A large thin-walled pair of hearts spring from either side of this 

 vessel by a very small connection in segments ten, eleven, twelve 

 and thirteen. A. very fine pair of vessels also spring from this 

 longitudinal vessel in each segment just anterior to the hearts, 

 and probably are present in segments eight, nine and fourteen* 

 as well. (Plate XXVII. Fig. 2.) 



There seems to be only a single median ventral vessel into which- 

 open the large hearts, but just before doing so each heart gives- 



