17 



Sec. II. List of species of Yertebrata from the Cretaceous 



FORMATIONS OF THE WeST. 



NATATOEES. 



HESPEEORNIS, Marsb. 



Hesperornis regaliSj Marsh. Amer. Jour. Sci. Arts, [1872, p. 56, 

 1. c, 1872, p. 360. 

 ISTiobrara group, or No. 3 of the Smoky Hill. 



GEACULAYUS, Marsh. 



Graculavus ancbps, Marsh. Amer. Jour. Sci. Arts, 1872, (iii,) p. 364. 

 Niobrara Cretaceous of the Smoky Hill. 



SAUEUEJj]. 



ICHTHYOENIS, Marsh. 



ICHTHYORNis DISPAR, Marsh. Amer. Journ. Sci. Arts, 1872, p. 344 



(iv,) and 1873, p. 74, (v.) February, 1873. 



Niobrara Cretaceous of the Smoky Hill. 

 lOHTHYORNis CELER, Marsh, loc. cit., 1872, p. 406, (iv,) Apatornis celer^ 



(name only,) loc. cit., Feb., 1873. 



Niobrara Cretaceous of the Smoky Hill. 



REPTIIilA. 

 DINOSAUEIA. 



AGATHAUMAS, Cope. 



The characters of this genus are derived from the typical sijecies A. 

 sylvestris, which is represented by dorsal and lumbar vertebrae, and an 

 entire sacrum, with the ilia, one nearly entire ; ribs, and a number of the 

 bones the character of which have not yet been positively ascertained. 

 One of these resembles the i^roximal part of the pubis ; others, portions 

 of the sternum, &c. 



On eight, and perhaps nine, vertehrce anterior to the sacrum, there is 

 no indication of the capitular articular face for the rib. This facet is 

 found, as in Crocodilia, at or near the base of the elongate diapophysea. 

 The centra are slightly concave posteriorly, and still less soon the ante- 

 rior face, with gently convex margins. The neural canal is very small, 

 and the neural arch short and quite distinct from the centrum, having 

 scarcely any suture. The neural arch has a subcubical form, partly trun- 

 cated above by the anterior zygapophyses. In like manner the base of 

 the combined neural spine and diapophyses are truncate below by the 

 square-cut posterior zyapophyses. The diapophyses are long and directed 

 upward ; they are triangular in section. 



There are eight, and perhaps nine, sacral vertebrse, which exhibit a con- 

 siderable diminution in the diameter of the centra. The diapophyses and 

 neural arches are shared by two centra, the anterior part of the latter 



Proceedings of the American Philosophical Society, 1872, p. 482. 



2b 



