88 



LAND MAMMALS IN THE WESTERN HEMISPHERE 



into three parts, the bones of which are 

 called respectively the tarsus, metatarsus 

 and phalanges, and the correspondence in 

 structure between manus and pes is close 

 and obvious. The tarsus consists typi- 

 cally of seven bones, which are tightly 

 packed and rarely permit any movement 

 between them. The upper row of the tar- 

 sus consists of two bones, which are pe- 

 culiarly modified to form the ankle-joint 

 and heel ; on the inner side is the ankle- 

 bone, or astragalus, the shape of which is 

 highly characteristic of the various mam- 

 malian orders. The upper or posterior 

 portion of the astragalus, 

 according to the position 

 of the foot, is a pulley 

 which glides upon the 



Fig. 40.— Left pes of Wolf, lower end of the tibia 



front side. Cal., calca- , . i u r- i 



neum. As., astragalus, and IS held hrmly in 

 N., navicular. Ch., cu- pia^g ^y ^hg internal and 



boid. Cn.l,Cn.2,Cn.3, ^ i n i 



internal, middle and ex- the external malleolus. 



ternal cuneiforms. MU, gg^^^ ^^ie puUey-Uke 

 rudimentary first meta- 



tarsal. Mi. J/-F, second surface the astragalus 



to fifth naetatarsals. „ii „„„4-„„„j-„ *„ „ 



Ph. 1, first phalanx. Usually contracts to a 

 Ph. 2, second phalanx, narrow ucck, which cnds 



Ung., ungual phalanx. • n ±^ i i 



/, rudimentary hallux. ^ » flat Or COUVCX head. 



ii-v, second to fifth The astragalus is sup- 

 ported behind (or be- 

 neath) by the heel-bone, or calcaneum, which 

 is elongate and extends well above (or behind) 

 the remainder of the tarsus ; it frequently has 

 a distinct articulation with the fibula, but more 

 commonly is not in contact with that bone. 

 The astragalus rests upon the navicular, which 



Fig. 41. — Left pes of 

 Man, Note the large 

 size of Mt. I, the met- 

 atarsal of the first 

 digit, or hallux. Let- 

 ters as in Fig. 40, ex- 

 cept Cb., cuboid. 



