NOTES ON SOME AQUATIC OLIGOCHATA. 187 
Notes on some Aquatic Oligocheta. 
By 
Ww. Blaxiand Benham, D.Sc.Lond., 
Aldrichian Demonstrator of Comparative Anatomy, Oxford. 
With Plates V, VI, and VII. 
ConTENTs. 
1. Anatomy and Histology of Hete- | 5. Stylodrilus Vejdovskii,n. sp., 
rocheta costata, Claparéde, p. 209. 
p. 188. 6. Genital organs of Naiselinguis, 
2. Note on Spirosperma, p. 206. p. 211. 
3. Note on Psammoryctes, p. 208. | 7. Supposed constancy of z in species 
4, Note on Tubifex, p. 209. of Nais, p. 218. 
Durine the present spring (1891) I had under observation 
at various times a number of aquatic Oligocheta, for the 
purpose of illustrating my lectures to the students here who 
were working at the group; and I came across several interest- 
ing facts, some of which are worth recording in these pages. 
Wishing to obtain examples of Oligocheta living on the 
sea-shore, I wrote to Mr. W. H. Shrubsole, of Sheerness, 
and he was good enough to obtain for me several gatherings 
from the neighbourhood. I wish to convey to him my best 
thanks for the energy and promptness which he displayed in 
acceding to my requests. 
Amongst these gatherings, living in dark, smelling, decaying 
organic detritus, I found Hemitubifex ater, Paranais 
littoralis, Clitellio arenarius, and Pachydrilus sp., 
together with a worm originally diagnosed very briefly by 
Claparéde about thirty years ago, which appears to have 
