caudalwards directed part of the vagina. The median uterine duet 
(Text-fig. 12) has a considerable length and is directed forwards. 
The uteri open into it immediately before Lang’s glandular vesicle. 
Thus the duet to this vesicle is not longer than the median uterine 
duet. Because of the development ofsphineter muscles, the epithelial 
tube, especially nearest the 
vesicle, has a beadlike appear- 
ance, while the compact 
outer muscular envelope, com- 
posed of circular and longi¬ 
tudinal muscular fibres, has 
an even contour as in pars 
interna vaginae. 
Lang’s glandular vesicle 
(Lv.) is an elongated oval, and, 
as the figures show, reaches 
a considerable size. Within 
the family it particularly resem- 
bles that of the genus Neostylochus. Its location near the vagina 
deserves to be mentioned. 
In one specimen the vesicle contains only a pulpy mass of 
granules stained with hematoxylin. In another specimen there are 
masses of sperma and egg-remnants. The contents seem to be in a 
State of disintegration. The wall of the vesicle has a distinet muscularis. 
Summarizing what has been said, we may say that the female 
apparatus in Leptostylochus is characterized by a more advanced 
differentation of a type already present in Neostylochus. The splendid 
development of the shell duet and of Lang’s glandular vesicle should 
particularly be remembered, as well as the presence of a special 
muscle sphineter in the distal end of the vagina. 
Within the family Stylochidae, the following genera possess a 
Lang’s glandular vesicle: Neostylochus, Idioplana, Idioplanoides, and 
Limnostylochus. The last two, with respectively 2 and 3 species, 
have a Lang’s glandular vesicle that is horseshoe-shaped. Aside 
from the differences mentioned, we find the closest resemblance 
in the female apparatus of Neostylochus. The male apparatus in 
Neostylochus is, on the other hånd, different in that the penis is 
.armed with a stylet, penis-sheath is present, as well as a true 
Text-fig. 13. Leptostylochus elongatus. Outer 
part of the vagina; sph, muscle sphineter; 
Lvep, epithelial wall of Lang’s glandular 
vesicle. 
