254 
TERTJAliY VEETEBRATA OF THE FAYtjM. 
arc s('])ar:itc(l vonirally by an interval of about 2 cm. The neural arcli is a comparatively 
narrow bar of bone connected antero-externally with the u])per border of the condylar 
jiromiiKMices l)y a thin bar of bone as described above ; on the front of the bar there is 
a low nu'dian rid^e {ii.sj).), but on the hinder face there is a Hat facet, against which 
the antero-\('ntral surface of the aich of the axis tits (see text-fig. 83, D). The 
transverse process (t.j*.) is short and massive and directed a little backwards; on the 
posterior face, immediately outside the edge of the surface for the axis, there is a small 
foramen, which, however, does not seem to perforate the transverse process, but merely 
leads into the bone. 'J’hc surfaces for the axis are wide above, narrowing ventrallv, 
and passing into the surface for the odontoid wuthout interrnption ; they are slightly 
convex from side to side. The ventral bar bearing the odontoid facet is stout and 
is produced dowinvards into a sharp-hooked hypa[) 0 })hysis {hijp.) ; from Lucas’s 
description * it seems that a similar process is present in the atlas oi Zeiujlodon cetoides. 
In the axis (text-fig. 83, B, ])) the odontoid process {od.) is short, blunt, and 
rounded, passing at least ventrally into the lateral surfaces {at.) for the atlas. These 
are (piadrate in outline, and nearly flat or even very slightly concave from side to side. 
The neural arch is high, and the neural spine high and massive ; it is triangular 
in section, the posterior surface being Hat, while the two anterior faces meet in an 
acute angle, the low'er end of which overhangs the odontoid process ; or the ventral 
face of this projecting portion of the arch is a flat facet which articulates with the corre- 
sponding surface on the posterior side of the neural arch of the atlas (text-fig, 83, D). 
The })osterior zygapophyses (jr~.) are well developed. The transverse j)rocess {t.p.) is 
a Hange of bone directed a little backAvards, and extending from the base of the neural 
arch to the ventral border of the centrum ; externally it is divided into an upper and 
lower process, and its base is ])eiforated obliquely by a vertebrarterial canal (c.c.). 
'i'he posterior face of the centrum is much broader than high ; it is slightly concave, 
and in this specimen the epiphysis is not completely fused with the rest of the centrum. 
The ventral face of the centrum is imperfect. The third cervical (text-Hg. 83, C, D) 
is remarkable for the extreme shortness of the centrum, which in the middle is only 
about 1’5 cm. through, while its wudth is at least 5 cm. The centrum is oval in 
outline, and is completed by anterior and posterior epiphyses {cp.), here still separated ; 
the anterior and posterior faces are slightly concave. The neural arch is higli, and 
rises into a short stout neural spine [n.sp.) directed a little backwards. Both the 
anterior {a.z.) and posterior zygapophyses {p-‘Z-) iwe Avell developed and nearly circular 
in outline. 'J'he transverse process {t.p.) is wide, and consists of a narrower up{)er bar 
arising from the base of the arch and a much broader ventral l)ar from the lower half 
of the centrum; these unite externally, enclosing a large verlebrarterial canal {v.c.), 
and forming a broad plate, the outer angle of which is produced a little downwards. 
* Amor. A'ut uralist, vol. .\xix. (ISOo) p. 71(5. 
