pancreaticum by the earlier writers. There were, however, between 
the two varieties in addition to the differences mentioned above in the 
size of the suckers several other slight internal discrepancies which 
leave no doubt that the two forms must be considered as two distinct 
species. Both are closely allied to each other and members of the 
same natural genus. The generic name hitherto usuallv adopted f< ir 
Distoma pancreaticum is Dicrocoelium ; indeed, the principal features 
of the anatomical structure are the same in Distoma pancreaticum 
and Dicrocoelium lanceatum (St. and Hass.), the type species of the 
genus. But besides this similarity in the main structure there are 
also certain differences which to my mind forbid placing Distoma 
pancreaticum in the genus Dicrocoelium itself , that is to say as it is 
represented by its type lanceatum. One of the most conspicuous of 
these differences lies in the thickness and the considerable 
breadth of the body which latter allows the testicles to take a 
distinctly lateral position at about the same level, whereas in 
Dicrocoelium sensu strictiori, owing to the narrow spindle-shaped 
outline of the body, the testicles are placed obliquely one behind the 
other. In Lyperosomum which is also closely related to Dicrocodium 
the two cross diameters are still more reduced, the members of this 
genus presenting to the observer an almost filiform body of about 
equal breadth and thickness in which the genital glands are found in 
a straight line one behind the other. In addition to the peculiar 
shape of their body the two Distoma pancreaticum differ from 
Dicrocoelium by the more complicated structure of their excretorj 
vesicle and the stronger development of their copulatory organs On 
llie whole, therefore, there is sufficient reason for creating a new genus 
for the two forms under discussion. 
I he question as to the correct denomination of the species was 
somewhat difficult to decide. Distoma pancreaticum was discovered 
in Japan, and became first known in Europe during the Paris Exhibi 
tion in 1 889, where the Agricultural School of Komaba exhibited a series 
of parasites among which there was a “ Distoma pancreaticum from 
the pancreatic duct of sheep,” and a “ Distoma pancreaticum var 
from the pancreas of sheep.” The new parasite was referred to in 
subsequent years by RAILLIET (1890) and JANSON (1893 and 1895) 
the respective papers deal with the anatomical structure and the 
pathological significance ol the parasite, they emphasise its 
