THE HIND-LIMB. 59 
b. The leg. 
i. The os eruris or tibio-fibula: a single bone rather 
longer than the femur, slightly curved, and 
expanded laterally at both ends. It presents along 
the greater part of its length a distinct groove 
indicating its correspondence with two bones, 
tibia and fibula, which in man and many other 
animals remain distinct from one another. 
ce. The ankle. Corresponding to the wrist in the fore-limb : 
consists of two rows of tarsal bones. 
a. Proximal row of tarsal bones: consists of two elon- 
gated bones united together at both ends, but 
widely separated in the middle. 
i, The astragalus: on the preaxial or tibial side. 
ii. The caleaneum: on the postaxial or fibular side: 
the larger of the two bones. 
@. Distal row of tarsal bones; consists of two very 
small bones. 
d. The foot. Has five complete digits, and a supernu- 
merary toe as well. Each digit consists of a proximal 
‘metatarsal bone, beyond which are a variable number 
of phalanges. 
i. The hallux, corresponding to the great toe of man : 
the preaxial digit, and the smallest of the series. 
Consists of a metatarsal and two phalanges. 
On the inner side of the hallux is the calear, 
supposed to be an additional or supernumerary 
toe. 
ii. Consists of a metatarsal and two phalanges. 
iii, Consists of a metatarsal and three phalanges. 
iv. The longest of the toes: consists of a metatarsal 
and four phalanges. 
y. The postaxial digit, corresponding to the little toe 
in man: consists of a metatarsal and three 
phalanges. 
