ECHIDNAS. 287 
has the elongated cylindrical form characterising anteaters of all kinds. The skull 
is devoid of all traces of teeth, and remarkable for the slenderness of its 
lower jaw, and its generally bird-hke form. Although there is nothing corre- 
sponding to the horny plates of the mouth of the duckbill, both the palate and the 
tongue are thickly beset with small spines. The body of the echidnas is remark- 
ably broad and depressed, with a sharp line of division between the spine-covered 
area of the back and the hairy under-parts. The tail is a mere stump ; and the 
short and sturdy limbs are armed with enormously powerful claws, varying in 
number from three to five on each foot. Although the front-feet are applied to 
the ground in the usual way, the hind-feet, in walking, have the claws turned 
outwards and backwards. The males resemble those of the duckbill in having a 
hollow spur at the back of the hind-foot, which is probably employed as a weapon 
in the contests between rival males during the breeding-season. The brain of 
the echidnas differs from that of the duckbill in that the surface is extensively 
convoluted. 
The common echidna (Hchidna aculeata), is a variable species, found in 
Australia, Tasmania, and New Guinea; and characterised by having five toes 

SKELETON OF ECHIDNA. 
on each foot, all provided with claws; those on the fore-feet being broad, while 
the others are narrow and more curved. In length the beak is about equal to 
that of the remainder of the head; and it is either straight or slightly turned 
upwards. The smallest variety inhabits Port Moresby, in New Guinea, and 
attains a length of about 14 inches; its distinctive feature being the shortness 
of the spines on the back. The toon from the Australian mainland is 
Jarger, and the spines are of great length. Larger than either is the Tasmanian 
variety, in which the length may be 19 inches ; the very short spines on the back 
being partially or eel hidden by the fur, the dark brown hue of which 
is frequently relieved by a white spot on the chest; while the beak is unusually 
short. 
The three-toed Echidna (Proéchidna bruijni), of North-Western New 
Guinea, is larger than any of these. Usually it has but three claws to each foot, 
but there is considerable variation in this respect, one specimen having five 
claws on the front, and four on the hind-feet. The beak is bent downwards, 
and attains a length equal to about double that of the rest of the head. The 
short spines are generally white, and the colour of the fur is dark brown or black, 
although the head may be almost white. 
Echidnas are fossorial and mainly nocturnal animals frequenting rocky 
