462 ANATOMY OF VERTEEKATES. 



mula is; — 7 cervical, 13 dorsal, 6 lumbar, 5 sacral, and 21 caudal. 

 The spines of the cervical are short, save in the last, and they in- 

 cline to that of the third cervical, as the centre of the movements 

 of the neck : these are facilitated by the ball-and-socket articula- 

 tions of the bodies, common to the true Ruminants with most 

 other Ungulates. The neural spine is longest in the third and 

 fourth dorsals, whence the spines gradually shorten to the tenth : 

 the metapophysis passes from the diapo^Dhysis to the zygapophysis 

 in the tenth, eleventh, and twelfth dorsals. In the first lumbar 

 the diapophysis exchanges its short, thickened, obtuse shape for a 

 long, broad, vertically compressed plate : these processes increase 

 in length to the fourth lumbar. The foramina for the spinal 

 nerves directly perforate the neurapophyses of the dorsal vertebra? ; 

 they escape by conjugational foramina at the interspaces of the 

 lumbar vertebrae. 



The European Bison has 14 dorsal and 5 lumbar vertebras, the 

 American Bison has 15 dorsal and 4 lumbar, and this is the 

 extreme reached, in the Ruminant order, of moveable pairs of 

 ribs, equalling in number those of the Hippopotamus. The ribs 

 are more slender in Bison than in Bos. 



In the Roan Antelope {Antilope equina), the vertebral formula 

 is : — 7 cervical, 14 dorsal, 6 lumbar, 4 sacral, and 14 caudal. 

 The atlas and dentata send out strong diapophyses : from that of 

 the third cervical a broad pleurapophysial ridge extends forward 

 and underlaps the diapophysis of the axis : a similar structure is 

 presented by the fourth and fifth cervicals, and in the sixth the 

 pleurapophysis forms a broad subquadrate plate extending down- 

 ward and a little outward. This element is absent in the trans- 

 verse process of the seventh vertebra, which is imperforate. The 

 dorsal spines begin progressively to shorten from the fifth ; that 

 of the thirteenth is vertical, and indicates the centre of motion of 

 the trunk. A metapophysis is developed from the front of the 

 diapophysis of the second to the ninth dorsal vertebrae inclusive, 

 where it begins to be transferred to the anterior zygapophysis, 

 from which it extends in the last four dorsals and in all the 

 lumbar vertebrae. There is a short anapophysis in the last two 

 dorsals, but not in any of the lumbar vertebras. Nine pairs of 

 ribs directly join the sternum, which consists of eight bones and 

 the xiphoid cartilage. 



These characters are found in the vertebral column of most 

 Antelopes. 



In the Wild Sheep of Thibet ( Ovis Nahura), as in the English 

 domestic Ovis Aries, the vertebral formula is: — 7 cervical, 13 



