SLOTHS AND THEIR HAIR 321 
their parents. As already mentioned, in very young 
individuals of the two-toed sloth a large proportion of the 
hairs are devoid of grooves; and it would therefore seem 
that the young sloths do not develop a growth of alga till 
about the time they are old enough to leave the maternal 
arms and hang independently on the leafy and lichen-clad 
boughs of their native forests. 
21 
