100 VETERINARY PARASITOLOGY 
projection, on which is situated the oval sucker. The 
posterior extremity tapers almost to a point. The 
suckers are two in number—an oval sucker, rounded 
in outline, and a ventral sucker, situated about 3 milli- 
metres behind it, which is larger and triangular. The 
alimentary organs, which are visible when the para- 
site is held between the eye and the light, consist 
of two main lateral branches, from which arises on 
either side a much-branched system. The parasite 
is hermaphrodite. 
The testicles are profusely branched, 
and occupy the middle third of the 
body. The uterus is situated imme- 
diately behind the ventral sucker, 
and opens by a short vagina on the 
ventral surface of the body, between 
the oval and the ventral suckers. 
Distomum Lanceolatum is not found 
in this country. It is narrower than 
Distomum hepaticum, and the two 
lateral alimentary canals are un- 
branched. Its life-history has not 
yet been worked out. Probably it 
is similar in most respects to that of 
Fic. 28.—Distomum Distomum hepaticum. 
eee Lije-History of Distomum Hepati- 
cum.—Distomum hepaticum is subject 
to an alteration of generations, involving a change 
of hosts. 
In the bile-ducts the adult parasite fertilizes itself, or 
a cross-fertilization is brought about by the union of 
two individuals. Asa result, in spring or early summer 
the worm migrates towards the intestine, and deposits 
its eggs either in the bile-ducts themselves or in the 
intestine. In size these vary from 20 to 80 y. They 
are oval in shape, and provided with an operculum, 
