78 G. A. MacCarrum, Notes on the genus Mierocotyle. 
As I have said in a former paper, certain worms seem to be 
limited to particular families of fish but it is impossible to say 
whether fishes in the wild state are as badly infested as those in 
confinement. It may be that the fish in this group belonging to 
different genera acquire their infestation with this particular worm 
from infected tanks even though all ordinary precautions are observed 
to keep them clean — a point which we shall attempt to clear up. 
