6 EISEN, PRELIM. REPORT ON GEN. AND SPEC. OF TUBIFICIDA. 
I will here only in a few words state my opinion of the 
structure of the generative and copulative organs, based upon 
observations made on some 17 new Californian and Scandi- 
navian species. 
The lower end of the glandular atrium constitutes the 
penis proper (fig. 1 to 6-p). This penis is always surrounded 
by several sheaths, some chitinous, one outside the other, 
and which do not connect with the atrium or with each 
other anywhere. The innermost sheath is generally cbiti- 
nous, covers the penis very closely, and is in the following 
allways called the penis- -sheath (fig. i stör6 ps TS glid 
is found in all species, except in Ilyodrilus, where its pre-' 
sence is very doubtfull. The size of this sheath is generally. 
diminutive, except in Limnodrilus and Camptodrilus (fig. 5 
& 6. Pp. s.), where the innermost or penis-sheath is long 
and narrow, and always extends along the outside of the 
penis. 
Surrounding the penis-sheath we find one or more chi- 
tinous or sacklike organs, generally only little exceeding the 
penis in size. Both those organs or sheaths, if two are pre- 
sent, are referable to, or constitute the oviduct proper. 'The 
interior one of these sheaths is generally chitinous (fig. 4 & 
3, in-ovd) and often of the exact appearance of the interior 
penis-sheath: so for instance in Limnodrilus alpestris and 
Camptodrilus spiralis (fig. 3 in-ovd). The interior sheath of 
the oviduct is very seldom sack-like or muscular (fig. 3 in-ovd) 
as in Limnodrilus ornatus and L. Steigerwaldi. The exterior 
sheath of the oviduct is on the contrary never chitinous, but 
always sack-like, sometimes muscular. (Fig. 1 to 6, ex.ovd). 
The interior entrance to or aperture of all these sheaths 
can always be seen, if instruments fine enough are employed, 
near the upper end of the penis proper, where the extended 
part of the atrium begins, but they are generally difficult to 
discern on account of their being covered with numerous 
lo ngitudinal or spiral muscles, one end of which is attached 
to the body wall, the other to the oviduct (fig. I to 6, in-apt). 
When two sheaths belonging to the oviduct are present at 
the same time, I have called the oviduet double (fig. 2, 3, 
4, 5), when, on the contrary, we meet with only one sheath, 
and that generally sack-like, we may appropriately call the 
oviduct single (fig. 1 & 6). The chitinous sheaths of the 
