166 
genera the vesicle attains a vertical position. Its reduced size in 
combination with its location in the interior of the penis near the 
apex may contribute to this unusual orientation. 
Among the Stylochids provided with Lang’s glandular vesicle 
we undoubtedly meet with the most primitive type in respect to 
the prostate in Idioplana and in yet undescribed forms allied to it. 
Woodworth's description gives hardly sufficient details, but the 
figure shows nevertheless the close relation to the penis, the original 
pearshape, and the primitive way in which the ductus ejaculatorius 
connects with the prostatic organ. A moderately thick (glandular?) 
epithelium covers its interior and is proximally slightly folded. 
Most Stylochids have the prostatic vesicle removed from the 
penis, a more or less long efferent duet being formed. They agree 
mostly in having a horizontal position of the vesicle, with the 
proximal, blind end directed forwards. The shape approaches often 
an ellipse (in Stylochus-species) but when the structure is simpler, 
can be more elongated and narrow (Neostylochus) or even club- 
shaped (Leptostylochus). The shape of the vesicle deviates most in 
Limnostylochus, as the organ appears here as a prolonged, sinuous tube. 
The vesicula granulorum reaches undoubtedly its largest size 
and highest specialization in the genus Stylochus. The excessive 
folding up of the interior lining has given rise to a great number 
of radial tubes. On a sagittal section through the vesicle .the lining 
appears corrugated and connective tissue projects into the folds as 
support. These latter septa would of course also show the tube¬ 
arrangement, if the glandular layer were removed. In the walls of 
the tubes or chambers a separation into two layers, as mentioned 
for Discosty lo chus and Meixneria^ is recorded for many species, i. e. 
a non-glandular epithelium covering a heavy secretion-layer. An 
intermediate stage between the Meixneria-Discosty lo chus-iypQ and the 
typical 5fy/oc/z«s-vesicle in respect to the structure of the vesicle 
is presented by Kaburakia. 
Leptostylochus offers an altered type. The epithelium of the 
vesicle, carrying whole giand cells, conforms so far to the Crypto- 
phallus-typQ. But it is also folded up in a way similar to that in 
Stylochus, thus gi ving rise to radial chambers. The connective 
tissue is, however, very sparse and contains no giand cells. It 
merely projects as thin lamellæ and forms a kind of skeleton of 
