XIII 



PHYLUM CHORBATA 



511 



or metatarsals of these digits unite to form a single elongated 

 bone, the cannon lone. 



The pelvis of most Ungulata is greatly elongated. The ilia are 

 wide transversely, the symphysis is very long, involving a part of 

 the ischia as well as the pubes. In the Perissodactyla, but not in 

 the Artiodactyla, there is a well-marked third trochanter. 



In some Ungulates (Rhinoceroses, Tapirs, Pigs, Hippopotami), the 

 fibula is distinct though slender. In the Horse it is represented 

 by a vestige. In the Ruminants it is represented only by a small 



n 



a. 



FIG. 1094. Dorsal surface of 

 right tarsus of Horse {Ef[V.us 

 I'aljallv.s). a. astragalus ; c. cal- 

 canexim ; cb. cuboid ; c 2 . united 

 meso- and ento-cimeiform ; c^. 

 ecto-cuneiform ; n. navicular ; 

 *'. scaphoid ; //, IV, vestigial 

 second and fourth metatarsals ; 

 ///, third metatarsal. (After 

 Flower.) 



FIG. 1095. Dorsal surface 

 of right tarsus of Red 

 Deer (Cervv.s elaphus). 

 a. astragalus ; c. cal- 

 caneum ; d>. cuboid ; c$. 

 conjoined ecto- and 

 meso-cuneiforms ; mt$. 

 mt 4 . third and fourth 

 metatarsals ; n. navi- 

 cular. (After Flower.) 



FIG. 1096. Dorsal surface 

 of right tarsus of Pig 

 (Sv.s scroj'a). a. astra- 

 galus ; c. calcaneum ; 

 cb. cuboid ; c3. ecto- 

 cuneiform ; c'-. meso- 

 cuneiforni ; m. meta- 

 tarsals ; n. navicular. 

 (After Flower.) 



vestige, the malleolar bone, which articulates with the distal end 

 of the tibia. 



The structure of the foot exhibits a close parallelism to that of 

 the manus. The tarsal bones are closely dove-tailed together, 

 and articulate with one another by flat surfaces. The hallux is 

 never developed. In the Perissodactyla the third digit is sym- 

 metrical in itself. In the Rhinoceros and Tapirs the second and 

 fifth digits are also completely developed ; but in the Horses 

 (Fig. 1094) they are represented only by splint-like vestiges of 

 their metatarsals, the metatarsal of the third digit forming an 



