492 CHORDATA. 
OrvDER I.—Jonotremata. 
There are two families in this order—(1) Ornithorhyn- 
chide and (2) Echidnidee, closely allied in many ways. 
Ornithorhynchus anatinus, or the duckmole, is found in the 
Australian region. Its 
Fig. 337.—Fore (A) anpD Hinp (B) general appearance may 
Foot oF THE DUCKMOLE. be seen from the figure. 
The body, usually about 
18 inches long, is cover- 
ed with dense, soft, 
brownish hair, and the 
head has a remarkable 
pair of horny “ beaks.” 
The eyes are small and, 
as in most aquatic forms, 
there is no external ear. 
Both pairs of limbs have 
five digits with claws and 
a “web” or membrane 
is present in the front 
limb, none in the hind. 
The tail is flat, and in 
old specimens the hair 
is absent from its lower 
surface. In habits the 
duckmole is ‘ fossorial” 
and ‘‘aquatic.” It swims 
freely and lives in deep 
burrows in river-banks. 
At the end of its burrow 
it constructs a nest in 
which it lays its eggs. 
There are no teats and 
f the mamma lands 
Note the bees ce eee as poison-spur are modifie cu Se fic 
glands. The teeth are 
only present in the young and adolescent forms and 
appear to be worn away early, when they are replaced 
by the familiar horny pads or “cornules” found in most 
skulls. The teeth are only molars and few in number, eight 
