346 THE ANATOMY OF VEETEBEATED ANIMALS. 



The Horse has seven cervical vertebrae, twenty-four 

 dorso-lumbar (eighteen or nineteen of which are dorsal), 

 five sacral, and about seventeen caudal vertebrae. The 



Fig. 95. 



J< 



Fig. 95. — A cervical vertebra of a Horse. 1. The rudimentary spine. 

 2, 3. The pre- and post-zygapophyses. 5. The convex anterior face 

 of the centrum. 9. Its concave posterior face. 6, 7. The trans- 

 verse processes and rudimentary ribs. 



atlas has very wide lateral processes, the faces of which 

 look obliquely downwards and forwards, and upwards and 

 backwards. The centra of the other cervical vertebrae are 

 much elongated, strongly convex in front, and correspond- 

 ingly concave behind. The neural spines are obsolete in all 

 but the seventh. The ligamentum nuchce is a great sheet of 

 elastic tissue, which extends from the spines of the anterior 

 dorsal vertebrae to the occiput, and is fixed, below, into the 

 neural arches of the cervical vertebrae. 



In the dorsal region, the opisthoccelous character of the 

 centra of the vertebrae gradually diminishes, though the 

 anterior face of the centrum of the last lumbar is still dis- 

 tinctly convex. The spines of these vertebrae increase in 

 length to the fourth or fifth. The spine of the sixteenth is 

 vertical, those in front inclining backwards, and those be- 

 hind a little forwards. 



In none of these vertebrae do the prezygapophyses bend 

 rotind the postzygapophyses of the vertebra in front, as is 

 often the case in the Artiodactyla. The transverse pro- 

 cesses of the penultimate, and of the last, lumbar vertebrae 

 present concave facets upon theii* posterior margins, which 



