i JIE OSTEOLOGY OF HYiENODON. 
531 
out of all proportion to the Wy and limbs, the neck short, the back, especially 
the lumbar reLnoiw>r it. nn fa i^nr. ^ v 
Kj± vviiiuii io veiy 
low down .... the s.des of the skull; in fro.it the maxillary alveolus forms a part of 
the /ygoma, winch thus seems to carry the sectorial molar, a very exceptional 
arrange.ne.it. The region of the cranium back of the glenoid cavity is very short, 
a featin-e winch .s usual among the creodonts. The low position of the zygomatic 
ai’ches inc-eases the appai-ent depth of the fiice, which, independently of this, is 
very considerable. Other chai-acteristic features of the head are the great length 
of the inaudible, which very' neai’ly equals that of the skull itself, its slenderness 
an.l the regular curvatui'e of its inferior horde.’. When the jaws are closed, the 
lower teeth, e.xcept the anterior ones, are concealed fi’om view, the upper molars 
extending over tlie sides of the mandible. 
I he neck 8ei*m.s vei’y short and slender to cari’y the weight of the large head, 
its length being liai’dly moi-e than two-thirds that of the skull. The axis is the 
only cervical vert.’hra which is sti’ongly developed and possesses a large spine; the 
olhe.’s iire weak. 
The tliorax i.s small, when compared with the skull, but measured by' any other 
standiird, it is (|uito large and capacious. The vertebral spines are developed much 
as in the Cai’iiivoi’a and the ti’ansverse processes and rib-tubercles are v'ery' conspicu- 
ous. The lumbar I’egion is long and powerful, the vertebrm having massive centra 
and long heavy spines, transverse processes, etc. These features are most marked 
in //. /lorridns, the smaller species having much less massive loins and evidently 
feebler muscles. The wluile back, fi’om the neck to the sacrum, is strongly arched 
upward and its parts are articulated together with unusual flexibility' and strength. 
The sacrum partakes of the character of the lumbar region, with prominent spines, 
while the tail is rather short .and slender, h.aving about the s.ame proportion.ate de- 
veloj.ment as in the r.aecoons. 
The scai.uhi is I’emarkably small and, with many peculiarities, is shaped not 
unlike that of the dogs. The hn.nerus is short and slender and the fore-arm bones 
still iiioix* so, though the ulna is stout .and h.as, as in nearly all the creodonts, a very 
p.'onunent olecranon. The inanus is relatively sm.all, short and broad, with spre.ad- 
ing digits and short phalanges, teriiiinatod by' heavy chaws. 
The pelvis is of moderate size, with expanded, flattened ilium, and is carnivorous 
rather than creodoiit in character. The femur considerably exceeds the humerus 
in length, but it is proportionately light and slender .and Ims ne.arly lost the third 
trochanter. The tibia is short, though much longer than the radius and the fibula 
stout, esiiecially .at the ends. The pes is small .and weak, not greatly exceeding 
the nm,,,.., in l..ngth. It in very difflenit t.. decide whether Hym.odon wan digit,. 
grade or jdantigrude in gait and several struetiirai characters may e a uce 
6i» JOURN. A. N. S. PHILA., VOL. IX. 
