THE HIND-LIMB 293 



fibula, bears an articular surface for the 

 astragalus. 



ii. The fibula, or postaxial bone, is very slender : 

 its proximal end is distinct, and articulates 

 with a facet on the outer surface of the head 

 of the tibia. 



Its distal portion is completely fused with 

 the tibia, and bears at its end an articular 

 surface for the calcaneum. 



3. The tarsus consists, in the rabbit, of six bones, arranged, 

 like the bones of the wrist, in a proximal and a distal 

 row, with a central bone between them. The typical 

 tarsus exactly corresponds to the typical carpus in 

 number and arrangement of bones. 



a. The proximal row of tarsals consists of two bones. 

 i. The astragalus, which probably corresponds to 



the tibiale and intermedium of the typical 

 tarsus fused together, is placed on the inner 

 or preaxial side of the tarsus : it articulates by 

 a prominent pulley-like surface with the distal 

 end of the tibia. 



ii. The calcaneum, or fibulare, is the largest bone 

 of the tarsus : it lies along the outer side of 

 the astragalus, articulating with the fibula, 

 and is produced backwards into the large 

 calcaneal process or heel. 



b. The central bone. 



i. The navicular, or centrale, is placed immediately 

 in front of the astragalus. It articulates with 

 the second metatarsal, and sends forwards a 

 large process along the ventral surface of the 

 foot. 



c. The distal row of tarsals consists of three bones, the 



innermost or preaxial bone of the typical tarsus 

 being absent, together with the digit which it 

 supports ; while the two outer tarsalia, like the 

 corresponding carpalia, fuse together., 



