156 



The depressed cups of the cervicals and anterior dorsals distinguish this 

 species from the Liodon validus, L. pronger, and P. mudgei. The same ele- 

 ments are much larger and more elongate than in P. ictericus. It differs 

 especially from these species of Platecarpus in the elongate form of the ante- 

 rior dorsals. In four of the latter, at least, the inferior limb of the dia- 

 pophysis is turned forward to meet the rim of the cup ; while this feature 

 ceases with the last cervical in L. latispinis. The articular surfaces have 

 planes at right angles to the axis of the centrum, and are not prolonged above, 

 as in P. gkmdiferus. The last hypapophysis is very short, with the anterior 

 margin transverse and elevated, as in the last-named species. 



Platecarpus glandifeeus, Cope. 



A smaller species than the last, with apparently a greater flexibilily of body, 

 as indicated by the forms of the vertebral centra. It is represented by por- 

 tions of two individuals from localities twenty-five miles apart. There is, 

 unfortunately, in each case, only a cervical vertebra; but they agree in pos- 

 sessing such peculiarities as distinguish them widely from anything yet 

 known to the writer. 



One is an anterior, the other a posterior cervical. The articular sur- 

 faces are transversely elliptic, and completely rounded above ; that is, neither 

 truncated nor excavated for the neural canal. Their shoiter axes are oblique, 

 i. e., make less than a right angle with the long axis of the centrum; and the 

 articular surface of the ball is thus carried forward on the upper face to much 

 nearer the base of the neurapophyses than usual, in the anterior vertebra 

 nearly touching them. The ball is, likewise, more convex than in any other 

 species, having a slight central prominence in the posterior vertebra. There 

 is no annular groove round the ball. In both, the articular surface of the 

 hypapophysis is truncate and bounded by an elevation in front, a peculiarity 

 not observed in any of the species already described There is no trace of 

 zygosphen in either. In the anterior vertebra, the diapophyses are nearly 

 horizontal; the posterior portion slightly thickened and oblique. The ante- 

 rior portion is thinned out, and very rugose above and below, and docs not 

 coutinue its margin into the rim of the cup. In the second vertebra, the dia- 

 pophyses are very large, vertical, and with a horizontal portion rising in a 

 curve to join the middle of the lateral margin of the cup. Neural spine nar- 

 rowed upward, and keeled behind. 



