THE NEPHRTDTA OF LEECHES. 553 



Hirudo. — Diagram of a nephridium, «. Funnel, b — c. Testis lobe. c—d. 

 Main lobe, e — d. That portion of the main lobe not represented in 

 Clepsine. e. Point where the recurrent ductules leave the main lobe 

 on their way to the apex g, and where the recurrent duct re-enters the 

 main lobe when returning from the apex g. e—f. Recurrent lobe ; for 

 the remainder of their course the recurrent ductules and duct traverse 

 the apical lobe,/— _^. g. Apex and point where the recurrent ductules 

 collect to form the recurrent duct ; this latter, as in Clepsine, returns 

 to e, re-enters there the main lobe, emerges thence at h to pass across 

 to the apex, and traversing the apical lobe returns to /, where it passes 

 across into the free end of the main lobe d; it emerges from the main 

 lobe at h. h—j. The vesical duct (efferent duct), j—k. The vesicle. 

 /. The aperture to the exterior. 



A B, CD, E F, G H. ScctioDS through the regions so marked, n, n. 

 Nuclei. 



Section a b shows the cells of the main lobe, with their branching 

 ductules ; the nuclei of these cells are drawn but not lettered. The cells 

 are grouped around two perforated cells, which contain the " recurrent " 

 and " main " portions of the duct, n, n. Nuclei in the walls of these 

 perforated cells. 



Section c d passes through the caecal end of the main lobe, and also 

 through the recurrent lobe. The main lobe section shows similar arrange- 

 ments to those shown in the section a b. The section through the re- 

 current lobe shows the recurrent ductules branching in the cells, which 

 are grouped around the perforated cell containing the recurrent duct. 



Section e f passes through one of the perforated cells containing 

 the vesical duct. 



Section g h passes through the numerous cells bounding the duct in 

 the last portion of its course, and lined internally by a prolongation of 

 the cuticle from the body surface. 



VOL. XXXIV, PART IV. — NEW SEE. 



