ORDERS OF MAMMALIA. 315 
swims with great facility. Their food consists chiefly of aquatic 
insects and molluscs, and they make very extensive burrows in 
the banks of streams. 
Fig. 170.—Monotremata. Duck-mole (Orutthorhynchus paradoxus)— 
after Waterhouse. 
The other member of the Monotremata is the Porcupine Ant- 
eater ot Echidna, which is not unlike a large hedgehog in 
appearance. The snout is very long, and is enclosed in a con- 
tinuous skin till close upon its extremity, where there is a small 
aperture for the protrusion of a long and flexible tongue. There 
are no teeth, or any organs to act as teeth. The feet have five 
toes each, and are furnished with strong digging claws, but the 
toes are not webbed. The skin is covered with strong prickly 
spines interspersed with bristly hair. The Echidna measures 
from fifteen to eighteen inches in length, and is a nocturnal 
animal. It lives in burrows, and feeds upon insects, which it 
captures by protruding its long sticky tongue. 
ORDER II, MARSUPIALIA.—The name of Marsupials is de- 
rived from the fact that the females of this order are mostly 
furnished with an abdominal pouch or marsuptum, within 
which the nipples are situated. When born, the young are 
placed by the mother within this pouch, where they adhere to 
the teats, and can be carried about without injury. Even when 
further advanced in their development, the young often betake 
themselves to the shelter of the marsupium. The so-called 
“marsupial bones” are present, and as they spring from the 
front of the pelvis they no doubt serve to support the pouch ; 
but this cannot be their sole use, as they exist in the males, and 
also in the Monotremes, in whom there is no pouch. All Mar- 
