Peterson: The Osteology of Promerycochcerus. 173 



there is a considerable exit posteriorly. The hei^iit of the neural 

 spine is less, but the antero-posterior diameter, especially near the 

 neural arch, is greater than in the preceding vertebra. 



The Eighth, Ninth, and Tenth Dorsals (Fig. l6). — This series of 

 thoracic ^•ertebr;e are similar to one another. Their centra are long, 

 narrow, and high; their lateral concave faces slope gradually from 

 above downward and inward, meeting in the median ventral line to 

 form a sharp keel. The transverse processes are shorter and the 

 capitular and tubercular facets for the ribs are closer together. Above 

 the tubercular facet on the transverse process is a heavy rugose 

 tubercle pointing upward and forward similar to that in the peccary. 

 The spine, especially on the eleventh dorsal, is more vertical and 

 otherwise begins to assume characters like those of the lumbar ver- 

 tebrae. These vertebra? have distinct intervertebral foramina, which 

 are nearly like those in cattle. In Merycoidodon culhertsoni the centra 

 of the vertebrae in the thoracic and lumbar region are distinctly more 

 depressed than in Pronierycochivnis cnrrikeri. 



17 18 



Fig. 1 7. Lateral view of the eleventh dorsal vertebra of Promerycochcerus carrikeri. 



No. 1 081; \ nat. size. 

 Fig. 18. Lateral view of the twelfth dorsal vertebra of Promerycochoerus carrikeri. 



No. 1 081; 5 nat. size. 



The Eleventh Dorsal (Fig. 17).— This vertebra is characterized by the 

 rounded and interlocking postzygapophysis and the usually vertical 

 or nearly anticlinal neural spine. The prezygapophysial facet of this 

 vertebra in the present species is quite small. The transverse process 

 is short and the ascending accessory process above the tubercular facet 

 is more robust and roughened than in the preceding vertebrae. The 

 intervertebral foramen is present. 



The Twelfth Dorsal (Fig. 18). — The twelfth dorsal has an anticlinal 

 neural spine, complete interlocking pre- and postzygapophyses and 



