120 BOARD OF AGRICULTURE. 
It is therefore probable that they are taken into the 
human system in impure water. In some regions it is very 
common. Davaine estimates that one-half of the inhabitants 
of Paris entertain this parasite. Its effects are not well made 
out, but it does not seem to cause, ordinarily, any marked in- 
convenience. It lives in the cecum and small intestine. 
Trichocephalus affinis Rud. 
This species lives in the coecum of cattle, sheep, deer, and 
antelopes. It closely resembles the preceding, but the neck 
part is still longer and more slender. The posterior end of 
the male is curved in a close, conical spiral, and the spicule, 
like its sheath, is much longer, being equal to about a third of 
the length of the body. The genital orifice of the female is 
situated at the summit of a prominent, hour-glass ‘shaped 
papilla, which is obliquely truncated at the summit and 
covered with minute spinules, like those of the spicule-sheath 
in the male. The eggs are similar to those of the preceding 
species and, without doubt, develop in the same way. It is 
not known to cause any serious disease. 
_ Spiroptera strongylina Rud., from the Hog. Figure 78. 
The genus Spiroptera includes numerous species of small, 
whitish or reddish, slender, round worms, which taper some- 
what toward the anterior end, or toward both Figure 78. 
ends. The head is small, and either naked, or 
with small papillae. The male has the posterior “ 
end curved in a spiral, with membranous expan- 
sions, and with two unequal intromittent 
spicules. In the female the posterior end of the 
body is nearly straight and conical, and the » 
ovary is either simple or double, with the genital 
orifice situated at one side of the body. 
The S. strongylina has a smooth, tapering body, with a 
simple head and mouth. The male spicules are very long, 
relatively to the entire length of the body. The male grows 
to the length of half an inch or more. The female to more 
than three-fourths of an inch. It lives in the stomach of the 
hog, but ordinarily does not produce any serious disease. 
a ae : 
Figure 78.---.Spiroptera strongylina ; a, male, natural size; }, spicules and pos- 
terior end of the body, enlarged, Brpmy Rasen 
