520 M. G. MEHL 



point. The distance between the capitular and tubercular facets 

 is about 38 mm. The articular faces of the zygapophyses are of 

 moderate size. The anterior pair are directed up and in; the 

 posterior pair, of necessity, out and down. The anterior pair 

 form a cuplike depression with a narrow antero-posteriorly directed 

 median sinus into which apparently extended a thin vertical sup- 

 port of the posterior pair of zygapophyses of the preceding verte- 

 brae, a condition that would apparently restrict somewhat the free 

 motion of the vertebral column. But little remains of the spine. 

 At the base it is 5 mm. thick and about 45 mm. wide. 



The sacrum consists of at least four, and probably five closely 

 united vertebrae with a total length of perhaps 230 to 290 mm. 

 It is considerably abraded and lacks most of the neural arch. The 

 centra of the component vertebrae rapidly decrease in size pos- 

 teriorly. The anterior face of the first is about 45 mm. in diameter. 

 All the centra are considerably constricted laterally. Apparently 

 only the anterior two vertebrae bear sacral ribs, though this is not 

 certain. The ribs were stout, somewhat flattened, and articulated 

 low on the neural arch near the mid-length of the vertebra. 



The caudal vertebrae are represented by the first and second 

 of the series. The second is nearly perfect and will serve well to 

 characterize the group. The centrum is 50 mm. long, somewhat 

 more deeply biconcave than the dorsals, and much constricted 

 laterally at mid-length. The articular faces are some 40 mm. wide 

 and 50 mm. high. Below there is a strong inter-centrum articula- 

 tion for the reception of chevron bones. These articulations are 

 well developed on both the anterior and posterior faces, but con- 

 siderably stronger on the anterior face of the vertebra. The dia- 

 pophyses are placed high on the neural arch and well back. Their 

 tips are slightly higher than the neural canal. They are short, 

 directed upward, and slightly back. From tip to tip they measure 

 42 mm. The zygapophyses are placed close together, the anterior 

 ones directed in and upward. The spine is long and thin and 

 directed very slightly backward. At the base it is about 5 mm. 

 thick and 35 mm. wide. The extremity is broken away, probably 

 no considerable portion, leaving the total height of the vertebra 

 135 mm. 



