WOODWORTH: SOME PLANARIANS FROM AUSTRALIA. 65 
The peculiarities of the male sexual organs of this form have necessitated 
the establishment of a new family for its reception (Diposthidæ). The salient 
feature is the separation of the penis and prostate gland into two distinct 
organs, both of which are doubtless intromittent. The prostate gland 
(“ Kornerdriise”) occupies the male genital atrium together with the penis, 
and lies posterior to it directly over the gonopore. It is slightly larger than 
the penis, and both organs are nearly pendent or perpendicular in position 
(Figs. 8, 9, and 11). The prostate gland is provided with a heavy layer of 
circular muscles, which together with the epithelial covering of the organ 
decrease in thickness toward the free end, and at the very tip are entirely 
+ . op . . . . 
lacking. I could not satisfy myself that there was an opening at this point, 
nor could I demonstrate any distinct lumen, which is explicable, possibly, by 
the fact that all of the specimens were in a late stage of sexual activity, all 
traces of testes, vasa deferentia, ovaries, and oviducts having disappeared, Two 
kinds of nuclei occur in the prostate gland, deeply staining nuclei which are 
found chiefly under the zone of circular muscles, and more lightly staining 
granular ones, which are accumulated at the free end of the organ (Fig. 9). 
The latter kind I am inclined to look upon as belonging to the glandular cells 
of the prostate. There are two large vesicule seminales the ducts of which 
unite to form the ductus ejaculatorius (Fig. 11). The seminal vesicles were 
filled with spermatozoa. The female gonopore opens into a large atrium, the 
walls of which are thrown into folds, and into which numerous unicellular 
glands, the shell glands, open. The walls of the chamber are also highly 
muscular, to function doubtless as a bursa copulatrix. Two of the specimens 
that were sectioned showed remains of uterine vesicles. One specimen exhib- 
ited two pairs of vesicles, and in the other there were three vesicles on one side 
of the body and two on the other side, with a third duct which ended abruptly, 
indicating the atrophy of the third vesicle of that side, In the specimen with 
but two pairs of uterine vesicles the vesicule seminales had also disappeared, 
but their ducts could be traced hack for a considerable distance from the penis. 
The full number of uterine vesicles can only be determined from material in an 
earlier stage of sexual activity. 
The uterine vesicles cannot be compared exactly with the uterine glands fig- 
ured by Lang? for Oligocladus sanguinolenta, for in that species they are 
only indirectly connected with the uterus by means of the oviducts. They 
are better comparable with the uterine vesicles of Uteriporus vulgaris of Ber- 
gendal,? and I look on the uterine vesicles of Diposthus as different chambers 
of a multipartite uterus, having at least six such parts. The vesicles of each 
side of the body communicate with a common duct, the ducts of opposite sides 
uniting to enter the female genital atrium (Fig, 11). As evidence that the 
1 Lang, A. Die Polycladen, Fauna u. Flora des Golfes y. Neapel, Monog. XL, 
Taf, XXI. Fig. 8, 1884, 
2 Bergendal, D Studier öfver Turbellarier. II, Om Byggnaden af Uteriporus, 
ete, Lunds Univ. Ars-Skrift, Fys, Sállsk. Handlingar, Bd. VII. 1896. 
