RIGGS: HOPLOPHONEUS OCCIDENTALIS. 43 



Smaller Larger 



Specimen. Specimen. 



mm. mm. 



Third premolar, breadth of crown 9 



Fourth premolar, breadth of crown 16 



Sectorial molar, breadth of crown 21 



Height of condyle above angle 27 



Length of condyle 39 



VERTEBRAL COLUMN. 



The cervical vertebra' are represented by the atlas, axis, and the 

 third, in the larger animal, and the seventh in the smaller 

 one. The atlas has a strong, rounded neural arch, but the ventral 

 arch is comparatively narrow and light. The rudimentary spine is 

 bifurcate. The transverse processes are too badly broken to be 

 determined. Their base is perforated posteriorly by the vertebrarte- 

 rial canal, which opens on the inferior surface further back than in 

 the lion. Here the vertebral artery ran for a short distance in a deep 

 grove and again passed under an osseous bridge forming an atlantar 

 foramen, as in Dinictis and the Viverridce. On the upper surface it is 

 again open for a short distance before passing under the anterior root 

 of the neural arch. The internal openings are much further back 

 from the anterior margin than in the lion. The centrum of the 

 axis is much compressed vertically. The inferior surface is divided 

 by a sharp median ridge, flanked by concavities. The neural arcli 

 and spine are lost. The third cervical has no spine, but a neural 

 prominence, which is bifurcate posteriorly. The vertebrarterial 

 foramen is very small, the anterior zygapophyses depressed, the 

 parapophyses directed more backward than in the lion. The 

 seventh has well marked rib-facets, and a slender spine. The 

 transverse processes are broken. 



Of the dorsal vertebrse. nine are preserved in the smaller animal, 

 many of which have lost their spines and transverse processes. 

 The centra are proportionally broader than in the lion, and are 

 produced into rounded lateral ridges which extend backward from 

 the base' of the transverse processes, and end in the capitular 

 facets. These facets are plainly marked, and in most instances 

 distinct from the intervertebral surface. In the first the transverse 

 process is proportionally longer than in the lion, the tiibercular 

 facet is concave and looks downward; in the seventh the facet is 

 also concave, but directed more outward; in the eleventh it is 

 concave, elongate and directed forward as well as outward, and 

 there is a deep fossa just back of it. The spinous processes are 

 long and slender, and instead of the sharp anterior borders found 



