510 
THE OSTEOLOGY OF HYvENODON. 
that of the last vertebra is nearly erect. The prezjgapophjses are exceedingly 
concave curving far over, and into them lit the convex, nearly cylindrical postzyga- 
pophvses. The metapoph vses are small, and on the last three vertebrm riidinien- 
tarv.^ In this species the loins are not for from being as heavy and powerful as m 
the" wolves. In the small, undetermined species the liimbars are relatively smaller 
and lighter, the neural spines are low, compressed and thin; the zygapophyses are 
more cylindrical in shape, and interlock more perfectly than those of the posterior 
thoracic vertebra) of the same specimen, but less so than in the lumbars of H. hor- 
ridiis ; the aiiapophyses are largest on the 1st vertebra, becoming rudimentary on 
the 4th. and are absent from the last three. In H. criientus the lumbars are inter- 
mediate in character between those of the two species above described. On the 
last lumbar, however, occurs a peculiar structure, which may be only an individual 
variation; the transverse process is short, but much extended antero-posteriorly, 
and abuts against the ilium, forming functionally a part of the sacrum, though no 
ankylosis with it exists. The process on the left side is much larger than on the 
right, and has a more extended contact with the ilium; a deep notch divides the 
j)rocess into two parts, the hinder one of which bears a large concave facet for the 
sacrum, which also is confined to the left side. 
The sacrum in young animals consists of only two vertebrm, to which in the fully 
adult form a third is added. The 1st sacral has a broad, depressed centrum with 
very large pleurapophyses, which carry the ilia almost entirely, the 2d vertebra 
having but a very limited contact with those bones. In H. horridus the 1st sacral 
has long and heavy transverse processes, which are quite distinct from the pleura- 
pophyses, and are directed obliquely Ibrward ; in H. cruentus these processes are 
much smaller, but still blunt and massive. The prezygapophyses of the 1st verte- 
bra are of the same pattern as those on the lumbars, but much louver; the neural 
canal is also very low, though quite as capacious as in the last lumbar. The spine 
is well developed and erect. The 2d sacral has a much narrower centrum than the 
1st and all its processes are less developed, except the neural spine, which in some 
cases IS larger and heavier than that of the 1st. In H. nmstelinus the spines of 
the eaormn arc rudimentary. The M vertebra h.aa a shorter and wider centrum 
is'^ill « horridm, tl,e spine 
The caudal veriar,c are seldom preserved in any considerable numbers One 
speemren, Imwcvcr, beleng.ng to the American Museum of Natural Ilislory h“ 
several verlcbrm from all parts of the tail, which rive an excellent idea f I 
p..rtions. Those show that Hymnadan had a tail of relativolv Lhl ‘^d ’Y 
the charnctcrof the vortebno is of distinctly carnivorous tvne ^ ^ ’ 
cats, though oil a very much smaller scale The t ■ ^ Oy^tnbling those of the 
Pliyses are rudimeu.ar, -1; hratre 
