of Vertchra from Cope Colony. 337 



known from the Karroo rocks of South Africa. It is in a 

 poor state c»f idescrvation, haviiiu^ travelK-il from hi^^hcr 

 ground, and by rollini; has lost the neural spine, zy<fa- 

 p()|)hyses, facets for the ribs, and is otherwise worn, B;if. 

 exposure has removed much of the intractable matrix, and I 

 liave cleared enough of what remained to show the more 

 important characters of the vertebra. It is an inch and a 

 half I'ing, with the centrum laterally compressed, showing 

 interccntral facets, with a central notochordal pit impressing 

 the centre of each articular face. The neural arch is not 

 cons| icuously elevated, is somewhat widened in front, and is 

 deeply excavated on the under surface for pneumatic foramina, 

 in the manner seen in the cervical vertebrae of birds and 

 vertebraj of Saurischian Dinosaurs. The external surface- 

 layer of bone is dense and smooth. 



The anterior articular face of the centrum (fig. 1, C, p. 338) 

 is wider transversely than deep, measuring fully six tenths of 

 an inch from the neural canal to the notched-out articular facet 

 for the intercentrum, and is eight tenths of an inch wide. This 

 surface of the centrum is convex from the central pit outward, 

 re.<embling the faces of the vertebra? preceding the caudal 

 fin of an Ichthyosaur, suggesting free movement; but it is 

 slightly rubbed and weathered. 



The facet for the intercentral ossification (I) is triangular, 

 wider than deep, placed below and behind the vertical arti- 

 cular face, and in lateial view looks obliquely forward and 

 downward, is rounded from side to side, and has the aspect 

 of excavating the base of the articular face (fig. 2, A.I). 



'J he posterior articular face of the centrum (fig. 1) has a 

 nnich smaller intercentral facet, chiefly resulting from its less 

 depth and more lunate form. The total depth of the posterior 

 surface of the vertebra a little exceeds the anterior depth 

 ( fig. 2, P.C), so that the articular face of the centrum was more 

 nearly circular ; it is inclined a little forward, making the 

 measurement along the neural canal about one tenth of an inch 

 shorter than along the ventral margin. A series of such 

 vertebra? would bo concave on the dorsal aspect, like the 

 vertebrse of the neck, elevated in the usual way. 



The body of the centrum measures about one inch and one 

 tenth from tront to back, along the narrow concave ventral 

 surface, between the anterior and posterior margins of the 

 intercentral facets. 'J'his inferior part of the body of the 

 vertebra is somewhat flattened from side to side, with a deep 

 median longitudinal groove in its middle length {^^. 1). It is 

 con)pressed from side to side, with the transverse width reduced 

 to little more than a quarter of an inch, at a quarter of an 



