MR. E. C. BOUSFIEED OX THE Q-EHU9 DERO. 
91 
The Natural History of the Grenus Dero. By Edward C. Botts- 
pield, L.R.C.P. Loud. (Communicated by Dr. J. Murie, 
F.L.S.) 
[Read 4th November, 1886.] 
(Plates III.-Y.) 
At the meeting of the British Association in 1885, at the request 
of Prof. McIntosh, I presented a summary of the results of 
my study of the Annelids of the genus Dero, with descriptions 
of some new species which had come under my notice, and 
remarks as to the identification of others. From the necessary 
limits of such a communication, I was compelled to omit 
much detail ; and lack of time and material led to a certain 
want of accuracy in my collation of the work of other writers, 
and the comparison of the examples which came under my own 
notice with their descriptions. 
Enlarged facilities of reference having now enabled me to 
acquire a tolerably complete knowledge of all that has hitherto 
been written on this genus, and a considerable supply of material 
from various sources having given opportunities for extended ob- 
servation and closer comparison, I venture to offer the following 
as the most complete account of the genus allowed by the present 
state of knowledge. Four new species having been met with in 
the course of the eighteeu months or more during which I have 
been working at these Annelids, it would appear probable that 
others still remain to be discovered ; and it is to be hoped that 
the publication of a summary of what has at present been accom- 
plished may facilitate future observation. 
History and Bibliography. 
The Annelids with which this paper deals, though their biblio- 
graphy covers a period of a century and a quarter, have hitherto 
been the subject of very little original work, owing probably to 
their habits of life, which prevent their presence in a state of 
nature from being easily discovered. In view of the great advances 
which have been made in methods of research, and especially in 
optical appliances, the very evident way in which the observations 
of earlier writers, and their interpretations (not unfrequently 
erroneous), have been copied by later authors, in many cases 
almost verbatim et literatim, is not a little surprising. 
