490 ALFRED GIBBS BOURNE. 



own. The chief point of difiference from Hirudo is that in 

 Aulostoma the ductules of the main lobe which collect at e 

 (woodcut, fig. 7), pass at once into a single ductule which winds 

 somewhat, but passes as a simple lumen perforating rounded 

 cells (the " apical lobe '') as far as g, where it changes the 

 characters of its walls, the cells taking on the drain-pipe form. 



Hsemopis, Hsemadipsa. 

 I have discovered funnels in these genera similar in structure 

 to the funnels in Hirudo. I may also state that the vesicle in 

 Hsemadipsa is very large, and the apertures to the exterior, 

 instead of being quite ventral in position, are actually dorsad of 

 the edges of the flattened body. 



Nephelis and Trocheta. 



The nephridium resembles that of other Gnathobdellidae and 

 presents only slight simplifications of structure. The chief 

 diflference lies in the structure and position of the funnel. I 

 have obtained isolated preparations of the funnel in both genera, 

 and so far as Nephelis is concerned I can testify to the 

 correctness of Ley dig's figure^, and Trocheta presents little 

 variation upon that type. 



There is following immediately upon the funnel a dilatation 

 (not figured by Leydig) such as described above in Pontob- 

 della, &c. This is seen in section in fig. 51, r ; it contains 

 the same mass of corpuscles as in the other genera. The funnel 

 and its dilatation lie in the hollowing in botryoidal tissue 

 described above as metacoelom (figs. 51 and 62, neph. fun.). 



General Conclusions respecting the Neph ridia. — The 

 nephridia present a serial arrangement with regard to their 

 metameric repetition. If my observations upon Branchellion 

 should prove correct there is in this genus very little expression 

 of such repetition ; the tubules do, however, become more 

 crowded together at regular intervals, no doubt an indication 

 of segmentation. It must, however, be borne in mind that 

 these observations rest upon the examination of a single young 



' Leydig, "Beiicht derK6nig.-Zootom.Anst.zu Wurzburg," Leipzig, 1S49. 



