STRUCTURE OF UROOHjETA AND DICHOGASTER. 279 
have been specially treated of in the present paper. I do not 
feel able at present to extend the diagram so as to embrace all 
the known genera, or even the greater number. 
I would point out, however, that the above scheme, though 
meant only to express the probable course of the development 
of the excretory system, does not do violence to the relation- 
ships in other structural characters between the different 
genera. 
List of Memoirs referred to. 
1. Beddard, F. E. — “ On the Occurrence of Numerous Nephridia iu the 
same Segment in certain Earthworms, &c.,” ‘ Quart. Journ. Micr. 
Sci.,’ Jan., 1888. 
2. Beddard, E. E. — “Note on the Mucous Gland of Urochceta,” 4 Zool. 
Anz.,’ 1887. 
3. Beddard, F. E. — “ On the Structure of a New Genus of Lumbricidae 
(Thamnodrilus Gulielmi),” ‘Proc. Zool. Soc.,’ 1887. 
4. Beddard, F. E. — “ Observations on the Structural Characters of certain 
New or Little-known Earthworms,” ' Proc. Roy. Soc. Edinburgh,’ 
1887. 
5. Beddard, F. E. — “The Anatomy and Histology of Pleurochaeta 
Moseleyi,” ‘Trans. Roy. Soc. Edinb.,’ vol. xxx, part ii. 
6. Beddard, F. E. — “The Structure of the Body-wall in certain Earth- 
worms,” ‘ Proc. Roy. Phys. Soc.,’ 1884. 
7. Beddard, F. E. — “New Zealand Earthworms,” 4 Proc. Zool. Soc.,’ 1885. 
8. Beddard, F. E.— “ The Anatomy of Three New Species of Earthworms, 
&c„” ‘Quart. Journ. Micr. Sci.,’ Oct., 1888. 
9. Beniiam, W. B. — “ Studies in Earthworms,” Nos. 1, 2, 3, ‘ Quart. 
Journ. Micr. Sci.,’ 1886. 
10. Beniiam, W. B. — “ Brachydrilus,” ‘Zool. Anzeig.,’ Bd. x (1887). 
11. Bergji, R. S. — “ Gcschlechtsorgane der Regenwiirmer,” ‘ Zeitschr. f. 
wiss. Zool.,’ Bd. xliv (1886). 
12. Bourne, A. G. — “ Anatomy of the Ilirudinete,” ‘ Quart. Journ. Micr. 
Sci.,’ J 884. 
13. Claparede, E. — “ llistologische Untcrsuchungen ueber den Regen - 
wiirrn,” ‘ Zeitschr. f. wiss. Zool.,’ Bd. xix (1869). 
14. Collin, A. — “ Criodrilus,” ‘ Zeitsch. wiss. Zool.,’ 1888. 
