THE ANATOMY OF AN AUSTRALIAN LAND PLANARIAN. 85 
Geoplana traversu probably agrees more closely in these respects with G. spenceri 
than any other form that has been examined, and this might naturally be expected. 
Moseley, however, does not describe (1) the uterus and vagina and the opening of the 
oviducts in any detail, and gives only a small figure of the external appearance of 
these parts when dissected out. In this figure the oviduct is made to open straight 
into the posterior end of the uterus. ' 
(d).—The Yolk Glands.—These consist of irregularly ramified masses of cells 
lying between the diverticula of the alimentary canal, and communicating with the 
oviducts by means of the short branches of the latter already described and shown in 
floure 34. ‘The yolk glands occur abundantly also behind the uterus and therefore 
behind the oviducts. How they here communicate with the oviducts I have not been 
able to determine. The yolk glands consist of closely packed, large cells with 
enormous, highly granular nuclei and very small protoplasmic bodies, as shown in 
fioures 34 and 35. They are doubtless homologous with what von Kennel (8) 
describes and figures in Rhynchodemus, but the nuclei are much larger and more 
eranular, and the protoplasmic bodies of the cells much smaller than they appear to be 
in that form. ‘There are no special ducts, but the masses of cells just come into 
contact at certain points with the branches of the oviduct, as shown in figure 34. 
Von Kennel figures precisely the same mode of communication between yolk glands 
and oviduct. Probably at the time when the ova are passing down the cells of the 
yolk gland simply break down and empty themselves into the oviduct. — 
Hence it would appear that the ova receive two distinct supplies of food— 
(a) In the ovary, deposited in the protoplasm around the nucleus and probably 
received from the spindle-shaped cells investing the immature ova; (0) im the oviduct, 
from the yolk glands. The food-material supplied by the yolk glands is probably 
simply enclosed in the cocoon together with the ova. The cocoon itself may be 
secreted by the brown glands discharging into the chamber into which the oviducts 
first open. 
It is interesting to observe that the yolk glands in Geoplana spencer: ave not 
present in all specimens, or if they be present it is in so rudimentary a condition that 
it is difficult, if not impossible, to identify them. 
Thus in specimens obtained at Haster by Professor Spencer I found no yolk 
glands, and had it not been for a specimen which I afterwards obtained at the same 
locality about the end of August of the same year, I might have entirely overlooked 
their presence. This difference may possibly be due to the time of the year, or it may 
simply depend upon the age of the animal. 
The Male Organs.—These consist of (a) the testes, (b) the vasa deferentia, and 
(c) the penis. 
