A NEW GENUS OF OLIGOCHiETA. 481 



In such sections the outer connective-tissue coat of the 

 intestine may be observed to include numerous tubules cut 

 across in various directions (fig. 5^ n), indicating therefore a 

 somewhat tortuous course ; these tubules appear, in sections 

 taken between two successive septa, to have no relation what- 

 ever with the nephridial tufts that have been already men- 

 tioned as occupying the coelom. And yet they are clearly 

 nephridial in their nature. 



Fig. 5 represents a slightly magnified section through a 

 portion of the intestine, showing the general appearance of 

 these tubes. 



Fig. 4 is a portion of the same more highly magnified, and 

 drawn with the help of the camera lucida. 



From this drawing it may be seen that the structure of the 

 tubes is precisely that of the nephridia, although they are for 

 the most part considerably wider. Their walls are granular, 

 with large nuclei interspersed here and there, showing the 

 lumen of the tube to be intra-cellular. 



In the section figured a smaller tubule is seen to project into 

 the lumen of the larger tubule, and another small tubule seen 

 in transverse section lies entirely within the larger tubule. 



This telescoping of one tube within another at once recalls 

 the peculiar structure of the leech's nephridium, made known 

 by the investigations of Bourne (15) and others. The dif- 

 ference is that in the leech the inner tube is closely invested 

 by the outer, while in the earthworm there is a wide space 

 between the two. 



These nephridial tubes, which appear to be so curiously cut 

 oflF from the general nephridial system, are in reality not so 

 cut off. A series of sections shows that they become con- 

 tinuous with the general nephridial network at the septa; at 

 any rate their branches pass along the septa, and can be traced 

 into the nephridial tufts : these branches are of the same calibre 

 as those of the general nephridial system. 



Traced in the other direction, these nephridial tubes 

 may be followed through the lining epithelium of the 

 gut, into the lumen, which they open. 



