150 PROCEEDINGS OF THE NATIONAL MUSEUM vol. m 



(33 mm.). The ventral surface and the lower portion of the right side 

 of the centrum is missing, the hinder portion of the left diapophysis 

 is broken off, and the neural spine is incomplete. The posterior 

 surface (36 mm.) is slightly wider than the anterior surface (33 mm.) 

 of the centrum, the prezygapophysial facets are flattened and slope 

 slightly from the external to the internal margins, the long axis of the 

 facet for the tuberculum on the diapophysis is nearly horizontal, and 

 the facet for the capitulum of the following rib is located on the centrum 

 at the upper posteroexternal angle. Although the neural spine is 

 broken off above the base, the curvature of the posterior edge suggests 

 that it was quite similar in conformation to that of Delphinodon 

 dividum. The backwardly projecting dorsal portion of the neural 

 arch is elongated anteroposteriorly (31 mm.) and relatively wide 

 (approximately 30 mm.) . The postzygapophysial facets are elongated 

 anteroposteriorly and slope obliquely downward and inward. The 

 slope from the dorsoexternal margin of the diapophysis to the inner 

 margin of the prezygapophysial facet is more noticeably oblique, as 

 contrasted with the horizontal position of these surfaces of Delphinodon 

 dividum. The diapophysis on each side of the neural arch bears a 

 broad ovoidal articular facet for the tuberculum of the corresponding 

 rib. The pedicles of the neural arch slope obliquely upward and 

 forward. The deeply concave lateral surface of the centrum is 

 continuous with the depressed outer face of the pedicle of the neural 

 arch. The epiphyses are relatively thin, firmly ankylosed, and con- 

 cave centrally. The dorsal surface of the centrum is depressed and 

 a minute foramen is located on each side of the thin longitudinal 

 median ridge. The other vertebra is an anterior lumbar (pi. 19, 

 fig. 2) that lacks the anterior epiphysis, transverse processes, meta- 

 pophyses, and the entire neural spine with the exception of the an- 

 terior basal angle. The centrum is longer than broad, its ventral 

 keel is quite sharp and curves concavely from end to end, and the 

 epiphyseal ridges radiate outward from the center of its concave 

 anterior and posterior ends. The transverse processes were ap- 

 proximately 29 mm. broad at the base. 



The pedicles of the neural arch are broad (minimum anteroposterior 

 diameter 24.5 mm.), rather flat externally, with concave anterior and 

 posterior margins, and slightly inclined forward. Above the level 

 of the transverse process, and for the most part posterior to the 

 hinder margin of the pedicle of the neural arch, the lateral surface of I 

 the centrum is depressed to form a fairly large shallow concavity. 

 Below the transverse process the lateral surface of the centrum is 

 markedly concave from end to end. 



