386 
PROFESSOR OWEN ON THE MEGATHERIUxM. 
PLATE XX. 
Fig. 1. The atlas, upper view. 
Fig. 2. The atlas, under view. 
Fig. 3. The atlas, back view. 
Fig. 4. The atlas, side view. 
Fig. 5. The seven cervical and first dorsal vertebrae, upper view. 
Fig. 6. The seventh cervical vertebra, back view. 
Fig. 7- The seventh cervical vertebra, side view. 
One-fourth natural size; c, centrum; n, neurapophysis ; t?.v, neural spine ; 
d, diapophysis, ds-dr, of the third to the seventh cervicals inclusive; 
pi, pleurapophysis ; pi, (fig. 7) articular surface for head of first dorsal 
rib ; m, metapophysis ; nz (fig. 2), anterior articular surface ; z' , posterior 
zygapophysis ; hy, hypapophysis ; o, (figs. 1 & 3) its articular surface for 
the odontoid or true body of the atlas ; r, division of the foramen alare 
posterius, for the passage of the posterior branch of the occipital artery ; 
s, division of the same foramen for the passage of a branch of the second 
spinal nerve; v, foramen alare anterius, communicating with q the canal 
for the vertebral artery. 
PLATE XXL 
Fig. 1. The axis, or vertebra dentata, front view. 
Fig. 2. The axis, or vertebra dentata, side view. 
Fig. 3. The third cervical vertebra, front view. 
Fig. 4. The third cervical vertebra, side view. 
Fig. 5. The sixth cervical vertebra, front view. 
Fig. 6. The sixth cervical vertebra, side view. 
One-fourth natural size ; o, odontoid process (centrum of atlas) ; zn, ana- 
logues of anterior zygapophyses, in the dentata ; 2 :, anterior zygapo- 
physis ; z\ posterior zygapophysis ; d, diapophysis ; p, parapophysis ; pi, 
pleurapophysis, pi, its anterior production ; in, metapophysis ; ns, neural 
spine. 
PLATE XXII. 
First sacral vertebra, with part of its haemal arch (ilium and pubis). 
One-fourth natural size ; c, centrum ; ** exogenous growths ; ma, rnetapophysial 
process and articular surface. 
