342 THE HIND FOOT OR PES. [ciiAr. 



the foot is attached. The naricular bone (//) is interposed 

 between the proximal and distal row on the inner, or tibial, 

 side of the foot, but on the outer side the bones of the two 

 rows come into contact. The distal row, when complete, 

 consists of four bones, which, beginning on the inner side, 

 are the three cuneiform bones, internal (^ 1 ), middle (r 2 ), and 

 external (^), articulated to the distal surface of the navicular, 

 and the cuboid (cl>] articulated with the calcaneum. Of these 

 the middle cuneiform is usually the smallest in animals in 

 which all five digits are developed; but when the hallux is 

 wanting, the internal cuneiform may be rudimentary or 

 altogether absent. 



The three cuneiform bones support the first, second, and 

 third metatarsals respectively, the cuboid supports the fourth 

 and fifth ; they thus exactly correspond with the four bones 

 of the distal row of the carpus. 



In addition to these constant tarsal bones, there may 

 be supplemental or sesamoid bones; one situated near the 

 middle of the tibial side of the tarsus, largely developed in 

 many Carnivora and Rodents; 1 another, less frequent, on the 

 iibular side ; and a third often developed in the tendons 

 of the plantar surface of the tarsus, especially large in the 

 Armadillos. There is also usually a pair of sesamoid 

 bones opposite each metatarso-phalangeal articulation, on 

 its plantar aspect. 



The development of the bones of the foot corresponds in 

 the main with that of the bones of the manus. Each tarsal 

 bone is ossified from a single centre, but the calcaneum has 

 in addition an epiphysis for the most projecting part or 

 tuberosity. The four outer metatarsals have each one 

 centre from which the shaft and proximal end are ossified, 

 and a large epiphysis at the distal end ; the first meta- 

 1 See footnote on p. 340. 



