COPE ON KEW EXTINCT VEETEBEATA. 391 



fundus. The faces, both lateral and inferior, are concave in all the cen- 

 tra, and do not display any sculpture of the surface. The fossae of ar- 

 ticulation of the neurapophyses of the dorsal vertebra are short and 

 wide, and have a deep transverse groove near the middle. Those of 

 the posterior vertebrae are pyriform, with the apices diverging, and ap- 

 proaching nearer the articular extremity than the wide portion of the 

 fossa does the opposite end. The wider portions are most deeply exca- 

 vated, and approach near together. The borders of the articular faces 

 are more or less bevelled or recurved. The sides of all the centra, includ- 

 ing the dorsal, present an obtuse longitudinal angle above the middle, 

 giving a hexagonal section. 



Measurements. 



M. 



\ antero-posterior 0.045 



Diameter of dorsal vertebra< transverse 0.046 



l^ vertical 0.046 



Length of fossa for neurapophysis 0,019 



[ antero-posterior 0.050 



Diameter of Inmbar ■( transverse 0.039 



\^ vertical 0.040 



Length of fossa for neurapophysis 0.018 



r antero-posterior 0.050 



Diameter of lumbar < transverse 0.036 



[vertical '. 0.038 



Length of fossa for neurapophysis 0.02O 



The vertebrae indicate for this reptile a size similar to that of a fully 

 grown alligator. Discovered by O. W. Lucas near Canon City, Colo. 



Amphicotylus lucasii, gen. et sp. nov. 



Char. gen. — The portions certainly representing this genus consist of 

 dorsal and lumbar vertebrae, ribs, and dermal bones. These indicate 

 that the form is to be referred to the amphiccelous division of the Cro- 

 codilia. The extremities of the centrum are regularly cupped, the eon- 

 cavity being separated from the edge of the articular face by a plane 

 border. The neural arch is co-ossified with the centrum, which does not 

 display any lateral fossa. It is, however, considerably compressed. 

 The diapophysis of the dorsal is below the neural arch, and near the 

 anterior extremity of the centrum. On the lumbars it rises from the 

 arch, and is long and flat. The anterior zygapophysis projects but lit- 

 tle from its anterior border, while the posterior forms a considerable 

 process. There is no hypapophysis on any of the lumbars, and proba- 

 bly none on the last dorsal vertebra. The tissue of the neural canal 

 presents a shallow excavation at the middle of the centrum, uniform 

 and rather finely spongy. 



The technical characters of this genus are somewhat like those of 

 JSympJiyrophus,* but the two forms are very distinct. The vertebrae of 

 the latter are amphiplatyan, not amphiccelous, and there is a lateral 

 fossa. 



•Palaeontological Bulletin, No. 28, 246. 



