284 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1949 
young until it is well able to take care of itself. There is a muscle 
around the entrance of this pouch which acts like a draw string and 
constricts the opening until it is very small, preventing foreign objects 
from getting in and the young from tumbling out. 
The very beautiful, graceful kangaroo rat mothers of North America 
lift their babies by grasping them by the back of the neck with their 
lips or teeth. They steady the little ones by holding them with the 
forearms, then hop along on their hind legs. This method of carrying 
the young was observed and photographed by that great naturalist, 
the late Vernon Bailey. 
The North American opossum is said to carry leaves and straw for 
its nest by wrapping the tip of its tail around the material. Some 
doubt exists, however, that this is an established habit, as only a few 
instances have been reported. 
As previously mentioned, gibbons, orangutangs and chimpanzees 
frequently carry objects grasped in their hind feet as well as in their 
hands. On one occasion I saw a chimpanzee pick up a piece of banana 
in one hand, a piece of bread in the other hand, and a head of lettuce 
with one foot. The ability to carry objects in the foot is particularly 
useful to animals that regularly traverse the forest by swinging by 
their arms from limb to limb. An orangutang carried a limb about 
2% inches in diameter and 8 feet in length from an outside cage to an 
inside cage in the National Zoological Park, handling it much of the 
time by grasping it with the hind foot (pl. 10, fig. 1). 
A number of the animals that burrow, particularly those that make 
extensive tunnels such as the pocket gophers of North America, the 
mole-rats (Cryptomys.and Bathyergus) of Africa, and the bamboo-rats 
(Rhizomys and related genera) of Asia, push the earth before them, 
placing the hands close’to the sides of the head and against the earth 
and supplying the motive power for moving the body forward by the 
hind legs. Others scrape earth rearward with the forefeet and then 
send it farther rearward by strokes of the hind feet. This is the most 
common method of those that do not make continuous tunnels. The 
prairie dogs (Cynomys) of North America move a great deal of the 
earth that they use in building mounds by this method, and they also 
push earth before them. 
Beavers carry at least part of the earth or mud they use by holding 
it against the breast with the hands. 
Elephants (Elephas and Loxodontia) pick up objects by encircling 
them with the trunk. 
Apparently both whales (Cetacea) and seals (Pinnipedia) some- 
times hold their young to their sides by means of the flipper. This 
procedure has been observed so rarely and for such brief glimpses that 
little is known of it. Whalers say that a mother whale sometimes 
