1877.] -^5 [Cope. 



chambers communicate with the cavity of the body by a large foramen 

 on each side, which is below the base of the diapophysis. In the cer- 

 vical vertebra it is very elongate; and extends between the bases of the 

 parapophysis and diapophysis. In the dorsal centra there are but two 

 chambers, which are separated by a longitudinal median septum. 



The neural arches are coossified with the centrum throughout the col- 

 umn. They are extraordinarily elevated, and their antero-posterior diam- 

 eter is small. The zygapophyses are at its summit, and have extensive 

 articulating surfaces. The anterior pair are divided by a deep median 

 fissure, while the posterior are united, and support as a pendant from their 

 inferior median line a hyposphen, a structure more fully described under 

 the head of the genus AmpMcoelias, where it is equally developed. When 

 the vertebrae are in relation, the base of the hyposphen enters the fissure 

 between the anterior zygapophyses, and maintains them in position . This 

 structure is obsolete in the lumbar vertebrae. 



The diapophyses rise from the neural arch to a considerable length up- 

 wards and outwards, in the anterior dorsals. They become shorter pos- 

 teriorly, but in none of the vertebrae anterior to the sacrum do they issue 

 from the centrum. In the caudal vertebrae they are short and robust, and 

 issue from the superior part of the centrum, They do not continue far on 

 the tail. Those of the dorsal vertebrae are light and concave below. They 

 are supported by thin osseous buttresses, the most important of which are 

 the two inferior ones. The anterior of these is much the most prominent, 

 and bears the capitular articular facet for the rib. In no case is this sur- 

 face seen on the centrum, but it descends somewhat in the posterior verte- 

 brae, but not as low as the level of the neural canal. 



The neural spines are rather short, and are set transversely to the axis 

 of the animal. The superior portion is expanded transversely, and in an 

 anterior dorsal vertebra, is widely emarginate above, so as to appear double. 

 The neural spines of the caudal vertebrae are compressed and elevated, 

 thougb thickened at the apex. The zygapophyses are situated low down, 

 and are directed very obliquely". The chevron bones of the caudal verte- 

 brae have short limbs which are not united at the base, and a long common 

 median spine. 



The sacrum is short and consists of only four vertebral centra, thoroughly 

 coossified. The anterior articular extremity is convex ; that of the poste- 

 rior extremity slightly concave. Its transverse processes are, like those of 

 the other vertebrae, much elevated, although they spring from the centra. 

 The external face of their bases is not prominent, and the spaces between 

 their projecting portions are deeply excavated. The centra are like those 

 of the caudal vertebrae, composed of dense bone. The extremities of the 

 adjacent transverse processes are united, thus enclosing large foramina. 



The scapula is relatively of large size. It is rather elongate, and the 

 superior extremity is expanded. There is a very large mesoscapular pro- 

 cess, which is wanting in Oetiosaurus, according to Phillip's figures. It 

 appears to resemble the scapula in Dystrophceus .* The tAvo proximal faces, 



* See Report of Lt. Wheeler, Vol. IV, pi. LXXXIII, p. 31. 



