200 



Order ARTIODACTYLA 



Skull subtriangular in frontal view, fig. lOSd; no prominent 

 ridge between horns or horn bases bison, Bison bison 



6. Top of skull with a groove extending from the inner side of 



the base of each horn (or knob) and meeting on the fore- 

 head to form a V or U, fig. 108a; horns usually present, 



subparallel, and directed posteriorly goat, Capra sp. 



Top of skull without such grooves, fig. lOSf, horns absent, 

 or diverging and downwardly curved 7 



7. Skull relatively long and narrow; posterior narial aperture 



completely divided by a vertical vomerine partition ; ant- 

 lers present or absent 



white-tailed deer, Odocoileus mrginianus 



Skull relatively short and wide; posterior narial aperture 

 without complete vertical septum; antlers never present. . 8 



8. Skull with sides behind eyes converging sharply, fig. 108f; 



bony eye sockets strongly protuberant 



domestic sheep, 01)15 sp. 



Skull with sides behind eyes rounded ; bony eye sockets not 

 strongly protuberant domestic calf, Bos taurus 



9. Skull more than 121/^ inches long (313 mm.) 



elk, Cervus canadensis 



Skull less than 12l4 inches long 



white-tailed deer, Odocoileus 'virginianus 



Fig. 109. — Teeth of ungulates: a, grinding surface of teeth of 

 cow ; b, outer side of teeth of cow ; c, tooth of horse. 



