COPE ON NEW EXTINCT VERTEBRATA. 389 



procured by my assistant, Mr. C. H. Sternberg, who obtained at one 

 locality the bones of the following birds:— 



Podiceps occidentalis, 



Fodiceps near calif ornicus. 



Podilymhus podiceps. 



Graculus niacropus, sp. nov. 



Anser hypsibatus, sp. nov. 



Anser canadensis. 



Anser albifrons gamheli. 



Anse7~ near nigricans. 



Gygnus paloregonus, sp. nov. 



Fulica americana. 

 These were associated with the following Mammalia: — 



Auclienia vitdkeriana, sp. nov. 



Auchenia magna {Palauchenia Ord). 



Auchenia hesierna. 



Equus major. 



Equus occidentalis. 



Eleplias primigenius. 



Canis latrans. 



Lutra near piscinaria. 



Castor fiber. 



Thomomys talpoides. 



Thomomys near clusius. 



Mylodon sodalis, sp. nov. 



Hypsirophus discurus, gen. et sp. nov. 



A form of this order has recently been discovered in the Dakota beds 

 of Colorado by Mr. Lucas, which is quite different from those already 

 announced. The vertebrae resemble those of typical Dinosauria in their 

 solidity and slightly amphiccelous extremities and in the wide discoi- 

 dal form of the proximal caudals, but differ from them in the extraordi- 

 nary elevation of the dorsal zygapophyses, which stand on a stem com- 

 posed of the neurapophyses. The anterior zygapophyses of the dorsal 

 vertebrae are united on the middle line, forming a basin, which receives 

 the posterior zygapophyses. This is not the case in the anterior caudals, 

 where the zygapophyses have their usual position, and the summit of 

 the neural spine is expanded transversely. This genus has been named 

 by me (American Naturalist for March, 1878) Hypsirophus, and the species 

 H. discurus. The dorsal vertebra of the latter measures 0™.105 to the 

 base of the neural arch, and O'^.SOO to the middle of the faces of the pos- 

 terior zygapophyses. The centrum is 0™.105 wide. The caudal centrum 

 is 0".175 wide and 0'^.160 high. The neural arch and spine are 0".575 high, 

 and the latter 0°».040 wide at the base and O'^.ISO wide at the summit. 

 The species was as large as Eadrosaurus foulkii. It is not impossible 

 that it may be the same as the Lmlaps trihedrodon Cope (Bull, TJ. S. 

 Geol. Surv. Terrs., 1877, iii, 806). 



