382 
Digenetic Trematodes in Japan 
Type species: M. truncatum n. sp. 
Microtrema truncatum n. sp. 
Diagnosis. Size: 12-13 mm. length, 4-5 mm. breadth in the widest part, 
1*5-2 mm. thick. Body tapers anteriorly, truncated posteriorly and com¬ 
monly turned dorsally. Cuticula with densely lying needle-shaped spines. 
Oral sucker situate at anterior end. Ventral sucker slightly posterior to middle 
of body, and smaller than the oral. Testes lie symmetrically, or one being 
often slightly anterior, margin slightly sinuate. Vesicula seminalis short, 
spindle-shaped. Prostate glands numerous. Ovary with numerous fine lobes. 
Receptaculum seminis large. Laurer’s canal without opening, ending blindly 
near dorsal body surface. Each vitellarium consists of about 10 ascinous 
groups. Uterus with numerous irregular loops, some of them barely reaching 
the intestinal caeca. Eggs brown, small, 0*026-0*03 x 0*013-0*016 mm. 
Found in the liver of hog. 
Externally this species resembles the genus Pachytrema Looss, but from 
its internal structure it may be referred to Motorchis truncatus (Rud.) = 
Pseudamphistomum truncatum (Rud.). 
Description. This species was found by Koidzumi (1911) in the liver of 
the pig in Formosa. It is 12-13 mm. long by 5-6 mm. wide in the widest part 
and 1*5-2 mm. thick in the thickest part. 
Body somewhat tongue-shaped. The postero-lateral margins are parallel, 
the body narrows quickly anteriorly, and posteriorly it is truncated. Ventral 
surface slightly convex posteriorly. Oral sucker situated slightly ventrally 
and usually elongated transversely, it measures 0*6 mm. in width. Ventral 
sucker situated a little posterior to the middle of the body and 7-7*5 mm. 
from the anterior end; it is round or transversely elongated and measures 
0-3-0-4 mm. Genital opening situated on median line and 1 mm. in front of 
ventral sucker. 
The colour of the specimens in alcohol is pale, a few being brown. The 
uterus and the vitellaria can be seen shimmering through. 
The cuticula is 0*02-0*05 mm. thick. It is armed all over with spines 
except postero-ventrally; the spines are specially numerous on the ventral 
surface; they are often arranged in threes or in fours; these groups are in 
turn disposed in transverse or diagonal rows. The spines are lance-shaped, 
0*01-0*02 mm. in length by 0*004-0*006 mm. in breadth basally; those on the 
ventral surface are larger and project while those on the dorsal surface remain 
in the cuticula. 
The three layers of the cutaneous muscles and dorso-ventra 1 parenchyma 
muscles are all well develooed. 
j. 
The oral sucker is followed by a short prepharynx which leads t6 the 
pharynx; the latter measures 0*5 x 0*4 mm.; the oesophagus is short, being 
slightly shorter than the pharynx and posteriorly it widens and soon bifurcates 
into the intestinal caeca, which run parallel with the lateral margins of the 
