xix.] GENERAL CHARACTERS. 311 



of the plantar surface of the tarsus. 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 is ossified, 

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



irsal (if it should be so called) and all the phalanges have 

 in epiphysis only at the proximal extremity. This rule is 

 ilmost universal, the most notable exception being found 

 in the Seals, in which animals (see Fig. 116, p. 315) each 



>f the metatarsals and all the bones of the toes, except 

 the terminal phalanges, have epiphyses at both, ends of 

 the shaft. 



Order Primates. — In Man (see Fig. 114) the foot is 

 >road, and in the ordinary standing position the whole 

 length of the plantar surface (at least its outer edge) rests 

 >n the ground, the main axis of the foot being at a right 

 ingle with that of the leg. The inner or tibial side of the 

 foot is arched before backwards, each extremity only rest- 

 )g on the ground. 



The tarsus is longer than the metatarsus, and the latter is 

 longer than the digits, but the forms and relations of the tarsal 

 bones are quite characteristic of the general Mammalian 

 type, and the five digits are present with the complete 

 number of phalanges. The hallux is much stouter than anv 

 of the others, though usually not quite so long as the second 

 toe. Its metatarsal is articulated to a nearly flat surface on 

 the internal cuneiform, directed distally, so that it is placed 



