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ing are moderately depressed. The balls of the dorsals are transverse elliptic, 

 with a slight concavity for the neural canal; the plane a little oblique to that 

 of the long axis. The centra are more depressed posteriorly, where the balls 

 of the dorsals present rounded lateral angles. On the lumbars preceding the 

 caudals, the base of the neural canal becomes more elevated, and the articular 

 faces assume a slightly pentagonal outline. This form continues as far as our 

 specimens of caudals extend. On three lumbars, the centra present two longi- 

 tudinal angular ridges below, at whose posterior ends the chevron articular 

 surfaces appear on the first caudals. All present an incised annular marginal 

 groove to the ball. The surface, especially the inferior, is strongly rugose up 

 to this groove, especially on the dorsals. 



The axis is much shorter than in any other species here noted where 

 known. The neural spine has a very oblique superior margin, and is ex- 

 panded behind. The diapophyses are narrow, and continued as vertical plates 

 to the inferior face of the centrum at its anterior margin. The diapophyses 

 of the other cervicals have the usual horizontal limb, which is, however, 

 shorter than the vertical. In the anterior dorsals, they are directed more 

 obliquely upward, and are longer. These and all other dorsals maintain a 

 connection between the rim of the cup and the anterior basis of the diapo- 

 physis by a smooth area apparently capped by cartilage in life, as exists in P. 

 curtirostris. As we pass posteriorly, these processes descend, and become 

 narrower, until finally they thin out and lengthen into the ribless diapophysis 

 of the lumbars. Those of the caudals are long and subcylindric. Their 

 extremities are deeply striate-grooved. The neural spines of all the vertebrae 

 are longitudinally striate-keeled. The zygapophyses are remarkable for their 

 narrow form and surfaces. 



The atlas is shorter on the outer and longer on the inner face than in L. 

 validus. This is caused by the fact that the posterior articular face is not 

 transverse, but very oblique, and, instead of being vertical and narrow, is 

 obliquely longitudinal in its long axis. It is separated from the inner face by 

 a wide rugose groove behind; its lower edge sends a keel downward. There 

 is no process at the thinned infero-auterior angle. 



The scapular arch is small, especially the scapula, which is absolutely 

 smaller than that of the Platecarpus ictericus, a very much smaller reptile. 

 The posterior margin is thickened, the anterior thinner, and less elevated. 

 The superior is arched upward and backward. The general form is less 



