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staining masses, which show a varying arrangement. The nucleus, as a rule, lies
close to the attached end of the cell.

       The ova, as they increase in size, project boldly from the surface of the
ovary. After reaching a certain size, they become provided with a funicle,
composed of altered cells of the ovarian wall. These cells are cubical or
columnar, and merge at the base of the funicle with the ordinary, rather flat,
cells of the ovarian wall. In the distended ovary, the funnel-shaped funicle is
flattened out. The funicular cells then form a flat plate, upon which the now
tightly bound down ovum lies. When the ova become mature, they are found
lying free and unattached in the lumen of the ovary. Quite how the change is
effected, by which the large ova at the end of a funicle come to be within the
lumen of the ovary, is not known, as intermediate stages are not often seen.
The process would appear to depend on a flattening of the funicle by the
pressure and growth of the large ovum, and the eventual forcing open of the ring
of cells by the same means.

       It is not uncommon to see, in the protoplasm of ova of a certain size, the
remains of one of the huge spermatozoa, which characterise Ornithodoros.
Spermatozoa are present in the ovarian sac, and it appears likely that fertilisation
often takes place in this situation.

       The fully mature ova, as they are seen after passage into the cavity of the
ovary, are globular, of a rich brown colour, and a millimetre in diameter. Their
protoplasm is densely packed with droplets of an albuminoid matter and with
fine granules. The nucleus is no longer visible. Attached to the ovum at this
time there is a curious structure the origin of which is doubtful (Pl. IV, fig. 7).

       The oviducts (Pl. IV, fig. II) are lined with long columnar cells, having
clear protoplasm and rather large nuclei, situated near the basal portion of the
cell. The outline of these cells is irregular, and they resemble in general
appearance the cells lining the œsophagus. External to the epithelial layer are
fibres of a muscular nature, and outside these a layer of curious large polygonal
cells with large nuclei. The lumen of the oviduct, especially in its lower
portions, is distended with masses of gigantic spermatozoa, which often exhibit
active and characteristic movements. The spermatheca is similar to the oviducts
in structure. It contains a number of spermatophores. The spermatophores
are bean-shaped or globular cysts, packed with spermatozoa. They have a
hollow stalk, from which the spermatozoa are discharged when pressure is made
on the cyst.

       The spermatozoa will be described later; but it may be mentioned that in the
female they are in a more advanced condition of development than when in the
male.

       The male organs of reproduction.—(Pl. V, fig. 6.)—Occupying the position