384 
Digenetic Trematodes in Japan 
(3) Eurytrema pancreaticum (Janson) (PI. XXIV, fig. 2); and 
E. coelomaticum (Giard and Billet) (PI. XXIV, fig. 3). 
In 1907, Loos 1 described two species of distomes which, infest the pancreas 
of cattle: viz. Eurytrema pancreaticum and E. coelomaticum. These had been ' 
regarded as synonymous. He distinguished them as follows: 
1. E. pancreaticum is larger and thicker than E. coelomaticum ; the body- 
length being more than 10 mm. long and the dorso-ventral thickness 2 mm., 
while E. coelomaticum is not more than 10 mm. in length and 1 mm. thick. 
2. The tongue-like appendage at the posterior end of the body is more 
marked in E. pancreaticum than in E. coelomaticum. 
3. In E. pancreaticum the oral sucker is remarkably larger than in 
E. coelomaticum and, in comparison with the body length, the distance between 
the suckers is greater. 
4. E. pancreaticum has the distinctly lobate testes, but E. coelomaticum 
less distinct ones. 
5. E. pancreaticum has larger vitellaria which contain more asci than 
E. coelomaticum. In the former they arise more anteriorly than in the latter. 
6. E. pancreaticum lays eggs slightly larger than those of E. coelomaticum. 
I have examined numerous specimens of distomes from the pancreas of 
Bos taurus and have observed these two distinct species as Looss distinguished 
them. My observations differ from those of Looss in the following respects: 
1. The two forms are of about the same size, both measuring between 
9*5-11*5 mm. in length. The thickness varies within the same range. 
2. The tongue-like appendage on the posterior end seemed to me to have 
no specific value, individual variation being large. 
3. The size and situations of the sucker are good criteria; for in E. pan¬ 
creaticum the oral sucker is 1*8-2 mm. in diameter, while in E. coelomaticum 
it is remarkably small, being 1*3—1 *5 mm. in diameter. The ratio of the 
diameters of both suckers is 10:7 in the former, and 8:7 in the latter. 
The distance between the two suckers in the former is 2*2 mm. (measured 
from the posterior border of the oral sucker to the anterior border of the 
ventral sucker), while in the latter it is 1*7 mm. on an average. 
4. Usually E. pancreaticum has distinctly lobate testes, while in E. coelo¬ 
maticum the lobulation is less prominent, but as many intermediate forms 
exist in both species, this characteristic is of little use. 
5. No distinction can be drawn from the relative situations of the vitellaria 
and the sizes of the eggs. 
I distinguish the two species as follows: 
E. pancreaticum (Janson). Body leaf-like, 10 mm. long by 4-6 mm. wide. 
Oral sucker 2*2 mm. in diameter; ventral sucker 1*4 mm. in diameter; the 
posterior situated at the posterior limit of the anterior half of the body. 
Testes and ovary usually obscurely lobate, the former consisting of 3-5 lobes, 
1 Looss, A. (1907), l.c. 
