H. K OBAYASHI 
381 
INTRODUCTION. 
The present paper is the outcome of my examination of a collection of 
trematodes from various parts of Japan (including Formosa). The species of 
monostome came from a turtle caught in Singapore. Of the material certain 
species are left unidentified chiefly owing to the paucity of specimens. It may 
be mentioned that in the following description the parasites are arranged 
according to their hosts. 
At the outset I must express my thanks to Professors Ijima and Goto, 
Tokyo Imperial University, and Professors Miyajima and Yatsu, Keio Uni¬ 
versity, for their generosity and suggestions. 
I. MAMMALIAN TREMATODES. 
(1) Clonorchis sinensis (Cobbold). 
It is well known that this species infests man, the cat, the dog and the 
pig. The rabbit, the guinea-pig and the rat can be artificially infested. 
Although it usually lives in the liver, yet sometimes it is found in the pan¬ 
creas and even in the duodenum. As to the structure of this species the reader 
may refer to the papers by several authors, including my own, on its anatomy 
and life-history 1 . It may here be mentioned that in my former paper the 
conclusion is reached that there is no difference at all between Looss’s 2 
Cl. sinensis and Cl. endemicus. 
(2) Microtrema truncatum n. g., n. sp. (PI. XXIV, fig. ]). 
Microtremci n. y. 
Diagnosis. Opisthorchiidae. Medium sized. Slightly flattened, but rela¬ 
tively thicker than other genera of the family. Taper anteriorly, truncated 
posteriorly. Cuticula densely spinose. Both suckers relatively small. Ventral 
and oral sucker widely separated. Intestinal caeca reaching to near posterior 
end. Excretory vesicle Y-shaped, stem branching into two arms near posterior 
end of receptaculum seminis; both arms are very long, run anteriorly close to 
the median line, and reach the exterior at a point near the intestinal bifurca¬ 
tion. Both testes lie symmetrically, slightly anterior to the branching of the 
excretory vesicle, and near intestinal caeca. No trace of cirrus-pouch. Ovary 
slightly anterior to level of both testes, lobate. Large receptaculum seminis 
present. Laurer’s canal without opening. Vitellaria consist of several 
ascinous groups. Uterus largely anterior to ventral sucker, in the space 
between both intestinal caeca, and not extending posterior to ovary. Genital 
opening slightly anterior to ventral sucker. Eggs small and containing mature 
mira^idia. Found in the liver of mammals. 
1 Kobayashi, H. (1917). On the life-history and morphology of the liver-distome (Clonorchis 
sinensis). Mitt. Med. Fachsch. Keijo, i. 
Looss, A. (1907). Some parasites in the Museum of School of Tropical Medicine, Liverpool. 
Ann. Troy. Med. and Parasit. i. 
o 
