44 
MONOTREMATA. 
•with a thick skin, particularly on the hack, where it has to 
support the strong spines: these are of a dirty-white colour, 
but more or less broadly tipped with black, sharply pointed, 
and average at about If- inches in length; they commence on 
the back part of the head, and extend over the whole upper 
surface of the body. The points of these spines are directed 
backwards, and on the back, inwards, so that they cross each 
other in the mesial line : near the root of the tail they form a 
large tuft, radiating from two approximate centres, and hide 
the small rudimentary tail. The head (with the exception of 
the hinder part of the upper surface), and the lower half of 
the sides of the body, as well ns the whole of the under parts 
and limbs, are covered with coarse brownish black hairs. 
The legs are short, and very strong ; the fore feet are short 
and broad, and armed with large, solid, and nearly straight 
nails— that of the middle toe being usually about an inch in 
length, and a quarter of an inch in width ; the shortest, which 
is found on the inner toe, is four or five lines in length : they 
are all rounded at the extremity. The hind feet are narrower, 
and less powerful, than the others, and have the inner toe very 
short, and apparently slightly opposeable; it is furnished with 
a broad and short nail, which is rounded at the extremity: 
the toe next the inner one is the longest, and is armed with an 
enormous claw, measuring sometimes an inch and a half in 
length; it is curved and nearly cylindrical, but concave be¬ 
neath ; the claws of the other toes are progressively shorter. 
Tlio hind foot, when in its natural position, rests on its inner 
side, and perhaps in a great measure upon the thumb or great 
toe: by this arrangement the long claws are protected from wear 
when tlio animal is walking, and they have the concave surface 
presented outwards. The use of these claws, it would appear, 
is to cast away tlio earth which is loosened by the stronger 
fore foot and claws. Like tlio Ornithorhynchus, tlio prosent 
animal has the heel armed with a strong spur in the male sox ; 
