72 



pressed ; they are opisthocoelous, but less so than in the Pro- 

 boscidea. They increase in size slowly but regularly from 

 before backwards. In the middle dorsal region they are ex- 

 cessively expanded laterally for the posterior-costal attach- 

 ments ; but become less broad and higher as they recede in the 

 series. In the middle of the series the centra are marked by 

 a prominent hypophysial keel. 



In the anterior dorsals the costal surfaces are developed 

 almost entirely upon the pedicles, and are two in number. 

 These are very large in about the sixth and seventh, and meet. 

 They decrease in size as they recede. In the middle region 

 the posterior costal surfaces are small, lozenge-shaped facets, 

 and are developed upon thin lateral projections of the centra. 



The centrum of the last dorsal is heavy, resembling the 

 centra of the lumbar, from which it is distinguished by a 

 single pair of small costal surfaces, developed, half on the 

 pedicles and half on the centrum. 



The neural spines are markedh^ smaller than those of the 

 Proboscidca and R/iinoccros ; in the anterior part of the dor- 

 sal region the spines have the same angle as the correspond- 

 ing ones in Mastodon. The spines of the twelfth and thir- 

 teenth (approximately) are much expanded at the ends and 

 bifid ; in the last dorsals they are wide, straight, and very 

 thin ; in the lumbar region the}' are short, stout, tuberous, and 

 stand almost at right angles to the axis of the vertebras. The 

 laminae in the anterior part of the series are long and thin^ 

 decreasing in length but increasing in thickness from before 

 backwards. The zygapophyses in the fore part of the dorsals 

 are mere flat facets on the laminae ; they increase in size and 

 become characteristic in the posterior part of the dorsal 

 region. The pre-zygapophyses of the last lumbar vertebra 

 are very large, deeply concave, and parallel with the axis of 

 the column. The metapophyses appear in the middle of the 

 series, and regularly increase in size to the last lumbar. From 

 their appearance the pre-zygapophvses are developed upon 

 them. 



The transverse processes present the most unique feature 

 of the vertebral column. In the anterior region they are 

 long, wide, and rugose, and in the same plane with the laminae ; 

 they send directly out wide, downward-curving projections. 



