1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 89 
genesis a third type of larve, the so-called ‘“‘cercaris,’’ which are 
furnished with a sucker and an actively moving tail. The cercarie leave 
the body of the snail and swim about in the water, finally attaching them- 
selves to aquatic plants, where they lose their tails and encyst. Fre- 
quently, too, the cercarie encyst free in the water. When eaten -or 
drunk by a sheep or goat, the cyst is dissolved in the stomach and the 
little parasite penetrates the intestinal wall, then from the peritoneal 
cavity into the ducts of the liver, where it develops into the adult 
fluke. , : 
In South America the intermediate host of Fasciola hepatica is, 
according to Ad. Lutz, a species of Lymnexa, while in the Hawaiian Islands 
Lymnexa oahuensis Souleyet is regarded as such. Iturbe and Gonzalez,} 
however, incriminate Pomacea luteostoma (Swainson) in Venezuela, 
while in the United States Boyd? suspects a snail which he calls Physa 
“fontinalis acuta.’’ In South Africa the host is not known with eertainty. 
Though Fasciola hepatica has been recorded from various localities 
in Africa, it is usually replaced there by a much larger species, F'asczola 
gigantica (Cobbold) (= Fasciola angusta Railliet). This parasite affects 
cattle and sheep, and has also been reported from certain big game, such 
as giraffes, zebras, and buffaloes, and very rarely from man. Its life 
history, recently worked out by Annie Porter,’ is similar to that of Fas- 
ciola hepatica. In South Africa the intermediate host is a common pond 
snail, Lymnza natalensis (Krauss). | 
Other liver flukes are especially adapted for parasitizing carnivorous 
vertebrates and in some countries they are frequently fourd tn domestic 
cats and dogs, and consequently occur also in man. One of these, the 
Chinese fluke, Clonorchis sinensis (Cobbold) (=endemicus Balz), occurs 
throughout southern Asia, from India to Korea, and in the East Indies 
and Japan. This parasite migrates through three hosts: the adult is 
found in vertebrates; the encysted cercariz occur in fresh-water fish; 
while the host in which the miracidia develop into cercariz is a fresh- 
water snail. At first several species of Thiaridse (Melanza in the old, 
broad sense), especially “Melania” libertina Gould, were suspected, 
but Muto‘! implicated Bulimus striatulus var. japonicus (Pilsbry) 
1Iturbe, J. and Gonzalez, E. 1919. “Quelques Observations sur les cercaires de la vallée de Caracas. 
Premiére Partie).’ (Caracas), 20 pp., 7. Pls. ae 
a Bord, M. = 1930 ‘A Neat oe intermediate host of Fasciola hepatica L., 1758, in North America. 
J . of Parasitology, VII, pp. 39-42. : ei 
OFT e eter sh gaie: #7920. Fhe life history of the African sheep and cattle fluke, Fasciola gigantica. 
South African Jl. of Sci., XVII, 1, pp. 126-130. See also Annie Porter, 1920, Med. Jl. of South Africa, 
XV, pp. 128-133. Leiper (1922, Tropical Diseases Bull., XIX, p. 364) erroneously refers Miss Porter’s 
experiments to Fasciola hepatica. ; as ihe 
i 4Muto, M. 1918. ‘Ueber den ersten Zwischenwirt von Clonorchis sinensis.’ WVerhandl. Japan. 
Path. Ges. Tokyo, VIII, p. 151. The snail is here called Bythinia striatula var. japonica. 
