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rior ventral margin of the gland. The two ducts which convey the 
secretion of the cement gland posteriad from the reservoir empty into 
the vas efferens in a region just anterior to the cirrus. 
Immature females taken in the month of October at Havana, 
Illinois, were in a stage of development just preceeding the destruction 
of the ovary to form the egg-masses (Eiballen). These specimens which 
were about 1,5 mm. long contained in the body cavity a single oval body 
for the ovary instead of a paired organ as so frequently described for 
other Acanthocephala. The ovaries in these immature forms were 
0,054 mm. long and 0,032 mm. wide. The egg-masses which result from 
the breaking up of the ovary vary considerably in size. They may 
be as large as 0,080 X 0,042 mm., while some are much smaller, 
0,040 0,022 mm. On the contrary considerable stability is found in 
the dimensions of the spindle shaped embryos (fig. 1) which are fairly 
constantly 0,036 0,010 mm. 
There are three regions of the female genital tract. The anterior- 
most of these, which is held in place by the suspensory ligament run- 
ning the length of the body cavity, is the selective apparatus. This ex- 
tends backward into the uterus which is followed directly by a more 
heavily walled vagina. The vagina communicates with the exterior 
through an opening slightly anterior to the posterior end of the body 
and on the ventral surface. In the region of the vaginal sphincter the 
vagina has a diameter of about 0,027 mm. 
This parasite occurs in the intestine and intestinal caeca of the 
gizzard-shad or hickory-shad, Dorosoma cepedianum (Le Sueur), taken 
from the Illinois River at Havana, Illinois, and at Peoria, Illinois. The 
period of infestation is confined to the fall, winter, and spring. The 
result of an examination of more than two hundred specimens of the 
host, extending through a period of over three years, has revealed a 
heavy infestation beginning in October when many of the Neorhynchi 
are small and immature, and continuing through the winter to April or 
May when the numbers decrease. Finally, beginning in May or June 
there is a period of freedom from these parasites. This immune period 
which continues through the rest of the summer must find explanation 
either in the nature of the food of the shad during that time or in the 
life-history of the parasite. During the period of infestation practically 
every specimen examined harbored some of the parasites, thus indicating 
that the intermediate host must be some common element of the food 
supply of the shad. The degree of infestation varied from a few indi- 
viduals in some hosts to over a hundred parasites from a single shad. 
