nt 
The adult organisation of Paragordius varius. 447 
(Atr Figs. 75, 79), where both bend and pass ventrad to open into 
the atrium at its dorsal antero-lateral angles, these descending portions 
of the tubes being the narrowest. Each oviduct has thus a horizontal 
and a vertical arm. The former portion consists of an epithelium 
(Ovi Fig. 49, Pl. 40) which is ciliated, this being the only ciliated 
epithelium in the whole body (in the male there is no ciliation at all) ; 
this epithelium has a lining of cubical cells of exactly the same 
character as the germinal epithelium which lines the uterus, but is 
thicker; the cilia (Cil) are arranged in tufts, not evenly scattered 
over the surface of each cell, and are simple cilia. The oviduct may 
be said to continue as far forward as the ciliated epithelium extends 
(Fig. 79, Pl. 42), namely to the plane of the penultimate pair of 
ovaries (Ov), the ciliation not extending into the ovaries. The vertical 
arm (Fig. 75, Pl. 41; Fig. 79, Pl. 42) of each oviduct is not ciliated, 
of a narrower calibre than the preceding portion, so that the ova must 
pass through it in single file. Very few spermatozoa are to be found 
in fertilized females in the posterior part of the oviducts; and it is 
probable that the ciliation acts to keep spermatozoa from penetrating 
into the uteri rather that to drive the ova backwards. The oviducts 
are imbedded in a small-celled parenchym (S. Par Fig. 49, Pl. 40; 
Fig. 75, Pl. 41). 
The atrium. The posterior end of this organ (Atr Figs. 78, 
79, Pl. 42) is coincident with the place of junction of the posterior 
intestine (P. Int) with the cloaca (Gl. Cl); its anterior end is produced 
in the form of two lateral horns which connect with the oviducts (Ovi), 
and into a medio-ventral continuation which connects with the neck 
(Rec. N) of the receptaculum seminis. The atrium is cylindrical and 
narrow posteriorly (Air Fig. 74, Pl. 41), anteriorly it becomes en- 
larged laterally and by median indentations from above and below 
shows an incomplete division into a right and a left half. It is lined 
internally by glandular epithelium (Air Figs. 74, 75) and externally 
by a sheath of small-celled parenchym (S. Par). The epithelium is 
produced into finger-shaped folds (GJ. C Fig. 51, Pl. 40) which project 
radially into its lumen, each fold representing a radial distribution of 
gland cells around an axial rhachis formed of the fused stalks of the 
cells. The gland cells are more or less coarsely vacuolar according 
to the stage of formation of the secretion, which is a thin, colorless 
fluid that does not imbibe any of the stains employed. It is probably 
this secretion, together with that of the glandular portion of the 
cloaca, which forms the hard, transparent egg membranes. 
