20 



E. C. CASE 



even rises slightly after leaving the spine ; at this point the pro- 

 cess is very thin vertically and quite broad in an antero-posterior 

 direction. The base of the transverse process rises from three 

 ridges, two rising from beneath the anterior and posterior zyga- 

 pophyses and a third vertical ridge on the side of the neural 

 ral arch. The base of the spine is quite broad and strong. The 

 spine was elevated. The pre- and postzygapophyses differ from 

 the cervicals in that their antero-posterior diameter is relatively 

 much less and the articular faces are no longer horizontal, but 

 inclined outward as well as downward and inward as well as 

 upward. 



MEASUREMENTS OF THE TWELFTH VERTEBRA. 



Length along the bottom line of the centrum - - - - 0.025™ 



Horizontal diameter of the posterior face of the centrum. - 0.028 



Vertical diameter same -------- 0.029 



Antero-posterior extent of zygapophyses . . . . 0.040 



Width of anterior zygapophyses ...--- 0.030 



The thirteejith to the sixteejith vertebras, inclusive, are very 

 similar to the twelfth, and all belong in the dorsal series; the 

 notable point is the gradual elongation of the centrum so the 

 antero-posterior diameter becomes greater than the vertical. 

 The neural arches are detached in all the dorsal vertebrae, but in 

 the seventeenth the arch lies near the vertebra and shows that the 

 character of the articular faces of the zygapophyses gradually 



change so that they are becom- 

 ing more and more horizontal. 

 The base of the neural spine is 

 very broad, but there is a deep 

 pit on either side. The anterior 

 face of the centrum shows an 

 articular face for an intercen- 

 trum. In Fig. 10 c is shown 

 an intercentrum, probably from 

 this region. It is noticeably 

 smaller than the intercentra from the anterior portion of the 

 column, and the faces for the capitula of the ribs are very small 

 and are not supported on tubercles. 



Fig. 16. — A dorsal, the sixteenth of 

 the restoration. a, from the side ; b, 

 anterior face of the centrum. % natural 

 size. 



