448 



ZOOLOGY 



SECT. 



centrum a Tpeg-Vika ^roce?,^— the odontoid po^oeesfi (od.) — which fits 

 into the ventral part of the ring of the athis : it has a compressed 

 spine (sj).), produced in the antero-posterior direction ; its transverse 

 processes are short and perforatetl by a canal for the vertebral 

 artery. All the cervical vertebra- except tlie last have their trans- 

 verse processes bifurcated into dorsal and ventral lamelhi\ The 

 seventh differs from the others in having a more elongated neural 

 spine, in having its transverse processes simple and without per- 

 foration for the vertebral artery, and in the presence on the 

 posterior edge of the centrum of a little concave, semi-lunar facet. 

 The thoracic vertebrse (C) have elongated spines which are mostly 

 directed backwards as well as upwards. The transverse processes 

 are short and stout ; each bears near its extremity a small smooth 

 articular surface or tubercular facet for the tubercle of a rib. On 



Fin. lOSl. — Iiepus cuniculus. yf, atlas and axis, ventral aspect, od. odontoid process of axis. 

 B, lateral view of axis ; art. articular facet for atlas ; oil. odontoid process ; pt. zij. post- 

 zygapophj'sis ; s.fi. neural spine. C, thoracic vertebra?, latei-al view. cent, centriim ; fac. 

 facet for rib ; inet. nietapophysis ; };/•.:». pre-zygapophysis ; -pt. z}i. post-zygapophysis ; /*. rib ; 

 sp. spinous process. 



the anterior and posterior borders of each vertebra is a little semi- 

 lunar facet, the capittdar facet {fac), situated at the junction of 

 the centrum and the neural arch. The two contiguous semilunar 

 facets of successive vertebra? form between them a little cup-like 

 concavity into which the head or capitulnm of a rib is received. 

 The semilunar facet on the last cervical vertebra forms, with that 

 on the anterior border of the first thoracic, the concavity for the 

 head of the first rib. 



In the lumbar region the spines are comparatively short, and 

 both transverse processes and bodies are devoid of facets. From 

 the centrum of each of the first two (or three) projects down- 

 wards a short flattened process — the liypapofliysis. Certain 

 accessory processes — the mctapopliyses {met.) and a.napoj)liyses — are 

 well-developed, the former being extremely long in the posterior 

 lumbar region. The metapophyses are situated in front, projecting 

 forwards and outwards over the pre-zygapophyses ; and the ana- 

 pophyses are situated below the jDost-zygapophyses and project 

 backwards. The transverse processes are long, and are directed 

 forwards and outwards ; that of the last lumbar is bifurcated. 



