The bursal rays are outgrowths of the lateral lines. Beside this “pulp” they contain a nerve, and at their bases complex muscles.
The Bursa is closed on all sides with a short median (ventral) lobe, which may be tucked inwards. It is an outgrowth of the inner layer of the skin pushing the outer layer before it, so that it consists of three layers, not four, as it would be if it were a fold. The bursa is twice as broad as long. It is supported by a variety of rays, the arrangement of which is best followed from the figure (fig. 327). The different terminology for these rays as used by various authors should be noted: Ventral = anterior; externo-lateral = antero-external; medio-lateral + postero-lateral or antero-median + postero-median = median (doubled); externo-dorsal = postero-external; dorsal = posterior. All the rays end in tactile papillæ, seven, on each side; the postero-external and antero-external on the outer surface of the bursa, the five others on the inner surface.[317] Of the six terminal digitations of the dorsal ray, only the external two contain tactile papillæ.
In the male there are prebursal papillæ and minute caudal papillæ in the female.
In the female the inner layer of the cuticle projects at the posterior end as a sharp spike, 20 µ long, which may sometimes be broken off.
Fig. 327.—Ancylostoma duodenale: bursa enlarged. Ca, anterior ray cleft; cle, antero-external; cls, antero-median; clp, postero-median; Cde, postero external; Cd, posterior bifurcated, each bifurcation tridigitate. (After Railliet.)
Ovaries.—The anterior tube runs from the cephalic to the posterior end and back again. The posterior tube begins anteriorly, runs to the posterior end of the body, and then back to the cephalic end, forming a vulval loop before ending. The ovaries on the whole run in oblique coils. The uterus is the thicker portion of the tube, 5 mm. long. A short tube connecting the ovary and uterus is the oviduct. The two uteri unite to form a single duct, the vagina, opening 1 mm. behind the middle line. The portion of the uterus next to the oviduct functions as a seminal receptacle, whereas the part next the vagina functions as an ovejector.
Testis.—The blind end begins a little behind the beginning of the cement gland. The transverse coils occupy the middle third of the body. About the middle of the body it passes into the spindle-shaped seminal vesicle, which, with the spicular canal and rectum, opens into the cloaca. An anterior longitudinal coil pushing in between the cervical glands is characteristic of Ancylostoma. The cement gland surrounds the ejaculatory duct for practically its whole course, and it occupies nearly the posterior half of the body and secretes a brown or black cement. The spermatozoa are curved rods about 2 µ long.
Spicules are 2 mm. long, ending in a fine point. They are moved by exsertor and retractor muscles. At first they lie free in the body cavity; next in a groove in the dorsal wall of the cloaca; then in an isolated canal, and finally in two canals. Anteriorly each has two longitudinal crests on its inner surface. These meet the corresponding crests of the other spicule, and so form a canal along which the sperm passes into the female. The gubernaculum is a thickening of the dorsal wall of the cloaca. It is not a free piece, but is moved by various muscles.