30 
Genus OPISTHORCHIS Blanchard,® 189S. 
cet Fluke (Dicro- 
codium lanceatum), 
•svith contained 
embryo, x 700. 
(After Leuckart, 
1889. p. 379, fig.171.) 
Generic diagnosis. — Fasciolidse: Body distinctly, often very greatly, elongated; 
anterior end attenuated, posterior end broader. Skin smooth, often without spines. 
Suckers not far separated, and usually not especially large. Inte.stine with pharynx, 
short slender esophagus, and long simple ceca. Excretory 
system with long sigmoid stem usually winding between 
the testicles, and with short branches. Genital pore 
median, immediately in front of aceta- 
bulum. Copulatory organs absent. Male 
organs: Testicles in posterior portion of 
body, one posterior of the other, more 
or less distinctly lobate, or even branched. 
Female organs: Ovary simple or lobate, 
anterior of testicles; Laurer’s canal pres- 
ent; receptaculum seminis very greatly 
developed; uterine coils anterior of tes- 
ticles and ovary, but not extending ma- 
terially over the intestinal ceca; vitellaria 
moderately developed, lateral of intestinal Fig. 40.— Egg of Lan- 
ceca, not extending anteriorly beyond 
the ventral acetabulum. 
Habitat. — Parasitic in the gall-ducts 
of warm-blooded animals (mammals and 
birds). 
Tvpe species. — Opisthorchis felineus (Rivolta, 1884). 
KEY TO SPECIES OF OPIS- 
THORCHIS REPORTED 
FOR MAN. 
(For species thus far 
found in the United 
States, follow Roman 
type. ) 
1. Testicles branched, 
and frequently ex- 
tending beyond the 
intestinal ceca into the lateral fields; excretory 
system runs dorsally of testicles; Asia, but im- 
ported cases elsewhere 0. sinensis (p. 35) 
Testicles mag he lobate, hut not branched, and are con- 
fined to median field between the intestinal ceca; 
excretory system sigmoid extending between the 
testicles 2 
2. Sj:)ines present on skin; vitellaria extend caudally of 
first testicle to about the anterior border of postenor 
testicle; worm not over 12 mm. long; ventral 
acetabulum close to bifurcation of intestine; 
India 0. noverca (p. 33) 
Spines absent; vitellaria not reaching or barely reach- 
ing the first testicle; ivorm 10 to 18 mm. long; ventrcd acetabulum some distance from 
bifurcation of intestine; Europe 0. felineus (p. 31) 
® Synonyms. — Opisthorchis Blanchard, 1895; Opistorchis Railliet, 1896 (misprint); 
“ Camjmla Cobbold,” of Stiles & Hassall, 1898 (in part) ; Opisthorchic Stiles, 1901 (mis- 
print). 
Fig. 41. — Free embryo (miracidium) of 
the Lancet Fluke; A, lateral mew; B, 
dorsal view. (After Leuckart, 1889, p. 
385, fig. 17.5 A, .B.) 
Fig. 39. — Lancet Fluke, 
enlarged to show the 
anatomic characters: ac. 
acetabulum; c. p., cirrus 
pouch; i, intestinal ceca; 
m, mouth with oral 
sucker; or., ovary; e, eso- 
phagus; p. h., pharyngeal 
bulb; t, lobate testicles; 
irf., uterus; va, vagina: vg, 
vitellogene glands. (After 
Stiles <k Hassall, 1894, PI. 
4, fig. 19.) 
