54 



rest on Iheiliiiiu; the posterior pair llie most expanded; tlie superior mar- 

 gins oi' its posterior edge form an open V, with the apex iorward on the 

 neural arch of the fifth vertebra. On the last sacrals, the diapophyses rise to 

 the neural arch again. The exits of the sacral spinal nerves are behind the 

 middles of the centra, and continue into grooves of the sides in all but the 

 last vertebrjE. The reduced and rather elongate form of the last sacral verte- 

 l)ra induces me to believe that this animal did not possess such large and 

 short caudal vcrtebrte as are found in the genus Hadrosaurus, and that the tail 

 was a less massive organ. 



The iUinii is much more elongate than the corresponding element in 

 Hadrosaurus, Cetiosaurus, or Megalosaurus. Its ujiper edge is turned and 

 thickened inward above the anterior margin of the acetabulum, and here the 

 middle of the conjoined diapophyses of the second and third sacral vertebra; 

 was applied when in place. In front of this point, the ilium is produced in 

 a straight line and a stout flattened form with obtuse end. Posterior to it, its 

 inner face is concave to receive the second transverse rest of the sacrum, and 

 the superior mai-gin is produced horizontally toward the median line like the 

 corresponding bone in u bird. The posterior j)ait of the bone is the widest; 

 for it is expanded into a thin plate and produced to a considerable length. 

 From one of the margins (my sketch, made on the ground, represents it as 

 the upper), a cylindric rod is pi'oduced still farther backward. This it is 

 believed is only the shaft of a displaced rib. The base of the ischium is co- 

 ossified with the ilium, and is separated behind its base from the iliac portion 

 of the acetabulum. There is no facet nor suture for the pubis at the front 

 of the acetabulum. 



The ribs are compressed. There are no bones certainly referable to the 

 limbs. 



The form of the ilia distinguishes this genus from those known hereto- 

 fore. 



Agathaumas sylvestrls, Cope. 



Proceedings of the American Pliilosopbical Society, 1872, p. 4"i'J. 



The last nine dorsal vertebras have rather short centra ; the most poste- 

 rior the shortest. They are higher than wide; the sides are concave, the in- 

 ferior face somewhat flattened. The neural arch is keeled behind from the 

 canal to between the posterior zygapophyses, and a similar keel extends from 

 the base of the neural sjiinc to between the anterior zyga])oj)hyses. The 



