The family of the 'Tubificid&e, and the systematical ar- 
ramngement of its species according to their anatomy, has for 
the last few years been the principal object of my study, 
and I have thought that perhaps a preliminary report on the 
general conclusions, at which I have arrived, may not be 
without some interest. 
The species of this family hitherto known have been 
both diligently and successfully studied by such eminent 
anatomists as CÖLAPAREDE, D UDEKEM, LANKESTER, PERRIER and 
VEJIJDOVSKY, and I can therefore hardly expect to add much 
to our knowledge of them. But in this, as in other families 
of the Oligocheta, the species are not by far so limited in 
number, as has formerly been supposed, and the many new 
ones, which I have found, will, as I hope, in some degree 
elucidate the anatomy and the systematical arrangement of 
the species of this the most difficult family of the Oligo- 
cheta. i 
In the following therefore I propose to give a short 
account of some new genera and species found in Sweden 
and California, and also a systematical arrangement of the 
species, founded on purely anatomical characteristics. 
The genera previously known are only three, viz. 'Tu- 
bifex, Psammoryctes and Limnodrilus, or at least the 4 to 5 
species sufficiently described to be recognized, can all be 
referred to one or the other of those three genera. Of these 
only Psammoryctes has been founded on anatomical charac- 
teristies, the two other genera have been distinguished by 
the presence or absence of hair-spines. 
So very few species of this family are however as yet 
known, that it is extremely difficult, if not impossible to 
decide upon with accuracy, what may and what may not be 
considered as a generic characteristic. HEspecially so, as we 
have very little knowledge of the variations of the interior 
