NOTES ON SOME AQUATIC OLIGOCHATA. 199 
the protrusible penis, which is surrounded by a specially 
thickened chitinous coat. The figures 18, 21, 22, representing 
the arrangement of this region of the duct, aid the descrip- 
tion. It will be seen that the male pore leads into a chamber 
(penial chamber, a, 5) lined by cuticle invaginated at the male 
pore. Projecting from the bottom of this penial chamber (or 
“cloaca” of Claparéde, or ‘‘ ductus ejaculatorius’”’ of Vejdov- 
sky) is the ‘‘ penis.” This consists of a soft central part, the 
‘‘ glans,” and a thick, refracting, chitinous coat (Vejdovsky’s 
“penis tube”), which has a characteristic form. It is nearly 
cylindrica!, the edge of the outer end of the cylinder being bent 
outwards so as to forma rim, and is much more noticeable than 
that of Psammoryctes, Spirosperma, &c. (cf. this with 
the penis of other members of the family). 
The internal soft part is perforated nearly axially by the 
narrowed continuation of the atrium, the external aperture of 
this duct being excentrically placed on a protuberant “ glans 
penis” (of Vejdovsky). I have not seen this penial apparatus 
in a protruded condition, but no doubta similar process occurs 
here as in Tubifex. 
When I first examined the genital duct, separated from the 
animal, I found that the “cement duct” (of Vejdovsky) and 
the ‘seminal vesicle” exhibited irregular dilatations, as seen 
in fig. 20,a@ and J. I therefore isolated some eight or nine 
ducts, in order to ascertain whether these dilatations were 
constant, and I soon found that such was not the case—that 
these swellings are only artificially produced. This was con- 
firmed by the fact that in situ there are not such definite 
swellings. 
In the fully mature worm Segments 1x to XIV, or even xv, 
are occupied by developing ova and spermatozoa. In some 
cases, such as the one figured, we find both genital cells fairly 
equally developed; whereas in other specimens the sperma- 
tozoa are predominant, and no large ova are present, and vice 
versa. 
The developing spermatozoa are included in definite sacs, 
the sperm-sacs, which are provided with thin membranous 
