CHAPTER YI. 



THE DORSO-LUMBAR VERTEBRAE. 



(Plates XXIII, XXIV, XXV, XXVI, LV and LVI.) 



The trunk vertebne in tlie Dinocerata are jiroportionally longer than 

 those in the cervical region. The articular faces of the centra are likewise 

 nearly flat, the most of them being distinctly concave. The epiphyses are 

 usually loosely imited to the centra, and thin, or imperfectly ossified, near 

 the center. The number of trunk vertebra- in Dbioccias was apparently 

 twenty-three. 



The First Dorsal Vertebra. (Woodcuts 95-98, below.) 



The first dorsal vertebra in Dinoceras mirahile (number 1255) has a 



slender, but elevated, neural spine, as shown in figm-e 95, below. It is 



distinguished from the adjoining elements of the colunni In- the presence 



of elevated and <»l)li(pie pre-zygapophyses, for articnlation with the 



last cervical. These processes are much farther apart than the post- 



zygapophyses, and look obliquely upward, inward, and slightly backward, 



while the latter look almost directly downward. Tlie pedicels of this 



vertebra stand mostly on the anterior half of the centrum. They are 



about twice as great in transverse as in antero-posterior diameter, and are 



directed well outward. l^lie lamina' form a much greater proportion of 



the neural arch than in the tapir, and are depressed at the middle, giving 



a somewhat triangular outline to the large neural canal. The epiphyses 



in this specimen are unossified for more than half their diameter, and 



imperfectly imited to the centrum. 



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