28 OSTEOLOGY. 



any other true vertebra ; this spine is convex, and consists 

 of lateral halves, united anteriorly into a strong rough crest, 

 but bifurcating posteriorly into ridges, which terminate in the 

 oblique processes. The inferior spine arises from a notch in 

 the inferior part -of the odontoid process ; it is broad and rough 

 anteriorly, but contracts into a sharp spine, which terminates in 

 a roughened tubercle posteriorly. The transverse processes, the 

 smallest in the cervical region, are single, and project outwards 

 and backwards ; they are pierced by very small vertebral foramina. 

 The spinal canal is somewhat narrow, and instead of notches, 

 there are two oval foramina anteriorly for the passage of the 

 spinal nerves. The posterior parts of the body and arch do not 

 materially differ from those of the other cervical vertebrae. 



In the horse the atlas and axis do not approximate above the 

 spinal canal, and there is a considerable space between them, the 

 atlo-axoid space, which is covered by soft structures only ; and 

 here the operation of " pithing " is easily performed. 



The Last Two Segments. 



The Sixth vertebra has a much shorter body than those 

 anterior to it, and is destitute of an inferior spine. Its trans- 

 verse processes consist of three lateral divisions, and its vertebral 

 foramina, notches and spinal canal are of great size. 



The Seventh vertebra, or Vertebra prominens, the shortest of 

 the series, is very strong and has an elevated neural spine, point- 

 ing upwards and forwards, but scarcely the trace of an inferior 

 one. Its oblique processes resemble the four preceding; its 

 transverse processes are small, and have usually no vertebral fora- 

 mina, while its notches and spinal canal are larger than in any 

 other of the last six cervical vertebrae. On each side of its 

 body, posteriorly, it presents a depression which, with a corre- 

 sponding depression on the first dorsal centrum, forms a cup for 

 the articulation of the first rib. Altogether it closely resembles 

 in character the first dorsal vertebra. 



DORSAL VERTEBRAE. 

 (PL. I. F.) 



These vertebras, of which there are eighteen or rarely nineteen, 

 always correspond in number with the pairs of ribs, and in the 

 horse form the weight-bearing portion of the column, extending 



