The young are born so helpless that they cannot even suck. The mother
places them in the external pouch, and fitting their mouths on the teats
injects the milk. After a time the young ones go out and in as they
please.]
It is not an easy haunt of life, but none the worse for that, and it is
tenanted to-day by representatives of practically every class of animals
from infusorians to seashore birds and mammals.