82 THE ANATOMY OF AN AUSTRALIAN LAND PLANARIAN. 
rod-like bodies. Certain terrestrial genera, which we may suppose have taken to land 
at a later date, still retain the multicellular type of eye which they inherited from 
their aquatic ancestors. Probably future research will show that terrestrial forms 
exist in which both types of eye occur. 
K.—The Reproductive Organs.—Geoplana spenceri, 1s, as might be expected, 
hermaphrodite, and provided with only a single genital opening, situate about half 
way between the pharynx and the posterior extremity of the body. Indeed, the 
reproductive organs agree essentially in structure with what Moseley and von Kennel 
have already described in the genera examined by them, and I shall therefore make 
my description as short as possible, enlarging only upon doubtful questions and 
such points of difference as exist. 
The Female Organs.—These consist of four principal portions—(a) The ovaries ; - 
(b) the oviducts ; (c) the uterus and vagina; (d) the yolk glands. 
(a) The Ovaries.—There is a sinele pair of ovaries, situate near the anterior end 
of the body, one on either side just inside the nerve cord. 
Kach ovary, as shown in figure 42, is a small, pear-shaped sac, with the narrow 
end pointing backwards. Its length is about 0-4 mm. It has no distinct investment, 
but the cavity of the sac is lmed by an irregular layer of epithelial cells, more or less 
polygonal from mutual pressure and with very large nuclei. Figure 44 shows a 
portion of this lming epithelium, in which the polygonal outline of the cells is 
unusually well marked. Amongst the epithelial cells, and perhaps forming a very 
loose and regular investment to the ovary, a few delicate, nucleated, spimdle-shaped 
cells may also be detected ; these are especially numerous about the point of entrance 
of the oviduct. In the interior of the ovary, ova in various stages of development 
are met with. As the development of the ova within the ovary does not appear 
as yet to have been very fully followed, I propose to describe it here in some detail 
(vide Figs. 44-49). 
Each ovum originates as an epithelial cell, at the periphery of the ovary (Fig. 44). 
The nucleus is already very large and highly granular, and in one instance I detected 
what looks like a small food granule, already deposited im the protoplasm (Fig. 44,/.g.). 
The ovum next separates from the lning epithelium and becomes amceboid (Fig. 45). 
At this stage spindle-shaped cells (sp. c.) begin to make their appearance, closely 
adherent to the surface of the ovum, and the protoplasm of the ovum contains very 
distinct globular food particles (f.g.). Figure 46 shows a somewhat older ovum, with 
four spindle-shaped cells adhering to its surface. Sometimes, as in figure 47, the 
nucleus at this stage shows a very distinct nuclear network. The spindle-shaped cells 
