70 
PROFESSOR OWEN ON REMAINS OF A LARGE EXTINCT LAMA 
An oblique upper view, one-fourth the natural size, of the second to the seventh cer- 
vical vertebrae inclusive, coarticulated, is given in Plate IV. fig. 6 ; an oblique under view 
of the third and fourth cervicals, coarticulated, is given, similarly reduced, at fig. 5. 
Figures of three of the more characteristic vertebrae are given, of the natural size, with 
the answerable ones in Auchenia and Camelus , in Plates V. & VI., and alone in Plate VII. 
The axis vertebra (Plate IV. fig. 6, 2 , Plate V. fig. 1) wants the major part of the odon- 
toid process, 0 , the right diapophysis, the end of the left one (Plate V. fig. 1, d), and the 
left postzygapophysis (restored in ib. fig. 1, from the right side at z'). This vertebra 
yields an entire length of 8 inches, the breadth anteriorly is 4 inches, the breadth of 
the posterior surface of the centrum is 2 inches 5 lines ; with the odontoid complete the 
length of this vertebra would be nearly 9 inches. 
The vertebrarterial canal commences within the anterior half of the neural canal, and 
emerges at the lower and lateral part of the fore end of the centrum within the exit 
canal ( e , e ') of the second cervical nerve, near the confluence of the odontoid process ; a 
forward continuation of the almost subsided ridge from the diapophysis ( d ) divides the 
nerve-outlet into an upper issue (e) for the dorsal, and a lower issue ( e ') for the sternal 
divisions of that nerve, near the latter of which outlets the arterial canal opens, being 
concealed from outer view by the bony bridge. 
Now this is precisely the condition of the nervous and arterial foramina in the vertebra 
dentata of Auclienia (Plate V. fig. 2, e, e'). In Camelus (ib. fig. 3) the dividing bridge 
is wanting ; the antero-lateral part of the centrum of the second cervical, at its confluence 
with the odontoid, presents a large longitudinally elliptic depression, e , into the hind part 
of which opens the vertebrarterial canal, and into the fore part the wider nerve-foramen. 
The part of the neurapophysis anterior to this is narrower in Camelus , relatively much 
narrower than in Auchenia , with which in this respect Palauchenia agrees. In the 
second cervical of Palauchenia the hypapophysial ridge commences at the middle of the 
centrum, gradually deepening backward, and rather abruptly expanding into an obtuse 
subelongate tuberosity (ib. fig. 1, hy) reaching the posterior articular surface of the 
centrum. In this character Palauchenia agrees with Auchenia (ib. fig. 2, hy) ; in Camelus 
the hypapophysis (ib. fig. 3, hy) expands posteriorly and divides into a pair of tuberosities. 
The bridge dividing the upper and lower nerve-outlets is continued backwards, in Palau- 
chenia, , into the angle dividing the lower lateral from the upper lateral surfaces of the ver- 
tebra, and this obtuse ridge or angle is gradually produced outward to form the long but 
low diapophysi-s, d. In Camelus the lower border of the elliptic depression (Plate V. 
fig. 3, e) is produced, sharpened, and continued backward into the diapophysis (ib. d). 
The neural spine (n.s.) in Palauchenia is a long low ridge, expanding posteriorly into 
a largish irregularly rough surface, which seems to have been simple or subbifid as in 
Auchenia ; it is certainly not so abruptly expanded, nor is it so distinctly bituberculate 
as in Camelus (the contour of the neural spine of which is indicated by the dotted line 
in fig. 3, to n.s.). 
