836 DR. p. E. BBDDARD ON A 



these openings is in the bladder region and the anterior one a 

 veiy little way in front of this. Both oi-ifices are dorsal oi* ventral* 

 in position — at any rate not lateral, — but they do not coincide 

 exactly. In view of the position of these orifices it is clear that 

 the tube of communication is of some length. In addition to 

 these t^^•o openings on to the extei-nal surface, the tube gives ofl' 

 two short ca^cal processes, one of which nearly but not quite 

 opens into the bladder. 



Anteriorly the tube gi'adually comes to an end and does not 

 end by opening on to the exterior. It diminishes in calibi'e for 

 the space of a few sections and then simply ends. At the bladder 

 end of the body — the end which is attached to the parent stock — 

 the tube gets to be more and more shoved to the side as the 

 bladder increases in size. In consequence also of this the tube 

 becomes flattened from side to side, at the anterior part of the 

 bladder. Followed backwards this tube can be recognised by its 

 thick chitinous lining, already i-efeii-ed to, and can be seen 

 thereby to be quite distinct from the excr-etoiy tube which has 

 come to lie below it in consequence also of the development of 

 the bladder region. The next that occurs is that the tube divides 

 into two coincidentl}' with the formation of two or thi-ee septa, 

 pai'tly dividing up the cavity of that part of the bladder which 

 lies adjacent. The two tubes lie one dorsally to the other, and 

 thus both of them in the same straight line with the excretory 

 tube. The middle tube of the two after a very short coui'se 

 appears to open into one of the chandiei'S of the bladder, and is 

 thus a diverticulum like the one mentioned above. Furthermore, 

 I am not absolutely certain that it actually opens into the 

 bladder ; but it ends at least in close contact. 



I feel, indeed, almost inclined to assert that this tube does 

 open into the cavity of the bladder, since the main tube, continu- 

 ing a little way further back, gets very narrow and undoubtedly 

 ends by opening into the bladder. It is to be noted that these 

 orilices do not involve a mere continuity of lumen. The character 

 of the lining membranes changes at the point of meeting. It 

 is further to be noted that it is not the main cavity of the 

 bladder into which the tube opens, but into a poi'tion of it, 

 separated off by septa. This problematical tube vai-ies in parts 

 in its structure and in its relations to the nerve-coi'd. Anteriorly 

 the layer of cells surrounding it ai'e not so conspicuous as 

 elsewhere, and thus the longitudinal muscular fibres come into 

 greater prominence ; the calibi'e of the tube also is not the same 

 all through the body. It has been mentioned that in a section 

 from about the middle of the body, that the tube lies outside 

 of the nerve-cord and quite latei'all)'- to it. In other parts of the 

 body, particularly antei'iorly, the tube lies above (or, pei'haps it 

 may prove necessaiy to say, below t) the nei've-cord. 



We have, therefore, in these young worms still attached to the 



* I cannot dirt'ennitiate betwoen tlie dorsal and ventral surfaces. 

 f See footnote above. 



