luternal Parasites. 227 
The Gid Tapeworm (Tenia cenurus). This parasite 
Dr. Cobbold observes, probably does not occur ‘in more, 
than 5 per cent. of our dogs. In the native dogs of Ice- 
land, according to Dr. Krabbe, it occurs in 18 per cent. 
In order, says Dr. Cobbold, to understand how the dog 
obtains this tapeworm, it must be observed that gid- 
hydatids, or cenurz, each represent a sort of colony of 
larval parasites. When, therefore, the dog eats a sheep’s 
brain containing a single hydatid, he swallows a colony 
of larva, each of the latter being destined to become 
transformed into a tapeworm in the bowel. Thus Fig. 26 
represents two hydatids, one being viewed from without, 
and the other from within. At A the young tapeworm 
heads are seen projecting from the exterior surface of the 
hydatid ; whilst at B they are seen retracted within the . 
interior of the bladder-worm. There may be from three - 
to five hundred of these heads projecting from the surface 
of a single gid-hydatid. 
LARV# OF THE GID TAPEWORM. (NEWMAN.) 
If a small fragment of the gid-hydatid with its charac- 
teristic processes be magnified about eighty diameters, all 
the more essential structures will be brought inte view. 
