OR OSSEOUS SYSTEM. 103 



interposition of clavicles. The elements of the sternum (y,) 

 placed in a line, are extended longitudinally, like the ribbed 

 part of the trunk, and are generally narrow and compressed 

 laterally. The long narrow scapulae (e,) have scarcely the 

 rudiments of the acromion and coracoid processes developed. 

 The humerus (/,) and the femur (q,) are generally short and 

 strong bones, much inclined from the vertical position, es- 

 pecially in the lighter and nimbler forms of this order. The 

 secure articulations of the long radius (h,) and tibia (s,) 

 admit of free flexion and extension, but are fixed in a state 

 of pronation. The imperfect ulna is anchylosed below to 

 the back part of the radius, and consists chiefly of an elon- 

 gated olecranon (g,) to secure the elbow joint and afford a 

 strong attachment to the extensor muscles of the arm. At the 

 lower end of the radius are found the four usual small carpal 

 bones of the first row separate, and the four of the second 

 row are here generally anchylosed into two pieces (i,) which 

 form the articulation with the long single meta-carpal bone (k.) 

 This broad meta-carpal, like the compressed meta-tarsal bone, 

 consisted in the foetus of two separate bones, and it retains, in 

 the adult state, longitudinal median grooves before and 

 behind, which mark the line of original separation. There 

 are often likewise the slender rudiments of two other meta- 

 carpal and two meta-tarsal bones seen, one on each side of 

 these long anchylosed bones of the meta-carpus (k,) and 

 metatarsus (t?,) and the rudiments of two corresponding 

 toes are found at the sides of all the feet. There are two 

 long pulley-like articular condyles at the lower end of the 

 meta-carpal bone, and there are three phalanges on each 

 of the two toes prolonged to the ground. The trochanter 

 major is large, and elevated on the strong and short femur 

 (q) ; the long and strong tibia (s,) forms the whole articulation 

 with the femur and with the astragulus (u,) and fibula forms 

 only a small splint. The calcaneum (/,) extends upwards 

 in the elevated heel, like the olcranon ( ^,) at the elbow. 

 Besides the astragulus and calcaneum, there are generally 

 two cuneiform bones, and a compound cubo-scaphoid bone 

 in the tarsus of ruminantia ; but there is one more bone in 

 the camel, as in the tarsus of the solidungulous pachyderma. 

 The long, anchylosed, compound meta-tarsal bone (v,) is more 

 compressed and narrow than the corresponding broad and 



