152 ZOOTOMV. 



112. The fibula, a slender bone also consisting of shaft 

 and epiphyses : its proximal end or head is narrow, and 

 articulates with the external tuberosity of the femur: its 

 distal end is widened laterally for articulation with the 

 calcaneum ( 114). 



113. Between the femur and the tibia is a thin, cartilaginous plate, 

 incompletely divided into two portions which answer to the internal 

 and external semi-lunar fibre-cartilages of man : each half contains 

 two calcifications or sesamoid bones which, in the dried skeleton, 

 are seen to be interposed two between each femoral condyle and the 

 corresponding tibial tuberosity. A large sesamoid bone is situated to 

 the outer side of this cartilage, and is interposed between the head of 

 the fibula and the external tuberosity of the femur. There is also a 

 small sesamoid attached to the ventral surface of the femur, just above 

 (proximal to) the external condyle. 



114. The tarsus, consisting of three bones divisible into 

 a proximal and a distal row : the proximal row consists of a 

 single large bone, the tibio-fibulare, representing the 

 ankylosed tibiale or astragalus and fibulare or cal- 

 caneum ; it presents two concave articular surfaces on its 

 proximal side for the tibia and fibula ; distally it articulates 

 by a somewhat pulley-shaped surface with the distal tarsals. 

 Of these latter the tarsalia only two are separate bones 

 in the adult ; one of these (tarsale 3) being a small, 

 calcified nodule in contact with the proximal end of the 

 third metatarsal, the other (cuboid or tarsale 4) a larger 

 bone giving attachment to the fourth and fifth metatarsals. 



The first and second tarsalia are ankylosed in the adult with the 

 proximal ends of the corresponding metatarsals ; the fifth tarsale is 

 absent. 



115. The bones of the digits correspond in number and 

 form to those of the manus, each consisting of a metatarsal 

 with two, three, four, five, and three phalanges respectively : 



