478 ALFRED GIBBS BOUENE. 



primary coelom remains, and the secondary coelom has not 

 yet appeared upon the scene. 



vii. Nephridia. 



Since the appearance of my memoir on the nephridium in 

 Hirudo,^ where a full account of the previous literature is 

 given, Arnold Lang^ and Oscar Schultze^ have dealt with this 

 subject, and in a second note* I have demonstrated the exist- 

 ence of proper walls to the so-called central duct, the lumen 

 being intracellular. The importance of this fact will be shown 

 below. Schultze's paper forms a most valuable addition to 

 our knowledge, correcting my previous observations, and, as 

 I have since convinced myself, rightly in some important par- 

 ticulars. Schultze also deals with Ciepsine, Nephelis, and 

 Aulostoma, and his results agree in the main with my own 

 independent observations ; these latter, especially with regard 

 to Pontobdella, to the existence of an internal funnel in 

 Hirudo, and to the above-mentioned fact regarding the nature 

 of the so-called central ducts, enable me to give a connected 

 description of the nephridia in the group of the Hirudinea. 



Pontobdella. 



Some of the nephridial funnels in this genus were described 

 and figured by Vaillant, but the network of tubules has 

 hitherto entirely escaped notice. Since the publication of a 

 note on this subject by the Royal Society^ I have spent 

 several months at Naples working at this subject, and the 

 results I then obtained are here incorporated with my previous 

 results. 



The nephridium in Pontobdella is without doubt the most 



1 'Quart. Journ. Micr. Sci.,' 1880. 



2 'Mittbl. Zool. Stat. Neapel.,' 1881. 



3 'Arch. f. mikr. Anat.,' ]883. 



'• • Quart. Journ. Micr. Sci.,' 1882. 

 * ' Proc. Roy. Soc.,' 1883. 



