THE OSTEOLOGY OF THE PIG. 315 



have the same relation as in the Horse. The third and fourth 

 digits are larger than the other two, and form a symmetrical 

 pair. There are sesamoid bones on the ventral face of the 

 articulations between the metacarpal and the basal phalanx, 

 and of that between the middle and the distal phalanges. 

 Each distal phalanx is incased in a sm^all hoof. The femur 

 has a round ligament. There is no third trochanter. The 

 fibula is complete, and its distal end articulates with the cal- 

 caneum. There are the usual seven tarsal bones. The tibial 

 end of the astragalus has the form of a deeply-grooved pulley, 

 the direction of the groove corresponding nearly with the 

 length of the foot. The distal end presents a convex sub- 

 cylindrical surface divided by a ridge into two facets, of 

 which one is somewhat less than the other, and articulates 

 with the cuboid. 



The metatarsus and phalanges of the pes are disposed like 

 the corresponding bones in the manus. 



The fore-part of the body is supported upon the anterior 

 extremities by a muscular sling composed of the serratiis, leva- 

 tor angull scapulm^ and sternoscapularis^ much as in the Horse, 

 with which the Pig exhibits a general correspondence in its 

 myology. The muscles which move the digits, however, have 

 undergone less modification. Each digit of the manus, for 

 example, has its proper extensors, and tliere is an extensor ossis 

 metacarpi pollicis Avhich ends on the basal phalanx of the 

 second digit. K pronator teres is inserted into the lower half 

 of the radius. The flexor perforatus has only two tendons, 

 which go to the third and fourth digits. ^\\q flexor per for an s 

 sends two large tendons to the third and fourth, and two small 

 ones to the second and fifth digits. There is a large inter os- 

 seus muscle on the radial side of the third digit, and another 

 on the ulnar side of the fourth ; but the interossei of tlie inter- 

 space between these digits are represented only by fibrous 

 tissue. The second and fifth digits have each two interossei. 

 There is no solens. The strong and fleshy plantaris arises 

 from the outer condyle, beneath the gastrocnemius ; and, en- 

 closed between the two heads of the latter, passes to the 

 inner side of the tendo Achillis / its tendon curves round this 

 tendon, passes over the end of the calcaneum as over a pulley, 

 enters the sole, and finally divides into the two perforated 

 tendons of the third and fourth digits. The inner and outer 

 digits of the pes, like those of the manus, have no perforated 

 tendons. 



A large and fleshy ^eiror hallucis longus arises from the 



