0. (. Mcureh — New Dmmawrian Reptiles. 83 



( '< ratops pauoidens. 



The specimen recently described by the writer under the 

 name Hadrosait^us paucidens* should probably be referred to 

 the genus GeratOpSy as a comparison with more perfect speci- 

 mens indicates a much closer affinity with that genus than at 

 first supposed. In addition to the maxillary described, one of 

 the premaxillaries is in good preservation. This agrees in gen- 

 eral features with the corresponding hone in Triceratope^ but 

 is less specialized. Its inner surface is deeply concave, show- 

 ing that the two premaxillaries did not meet each other closely, 



in TriceratopS) but apparently only in front. This species, 

 a> well as the type of the genus, Ceratops montanus % represents 

 smaller, less specialized forms of the family, and may be from 

 a lower geological horizon than the gigantic reptiles which the 

 writer has recently made known. 



In addition to the special characters of the Ceratopsidoe 

 shown in the skull, as stated by the writer in this Journal (vol. 

 xxxviii, p. 505), the following features seen in other parts of 

 the skeleton ma}' be mentioned : 



(1) The atlas and axis, and one or more adjoining cervical 

 vertebrae are coossified with each other. 



(2) Their cervical ribs are likewise firmly united with the 

 same vertebrae. 



(3) The remaining cervical vertebrae are short, and have the 

 articular faces of the centra nearly flat. 



(4) The trunk vertebrae have very short centra, with flat 

 articular ends. Above the centra, they resemble the vertebrae 

 of Stegosaurus. 



(5) The sacrum was strengthened by union with several 

 adjacent vertebrae. 



(6) The caudal vertebrae are short and rugose, and the tail 

 was of moderate length. 



(7) The ilium is elongated, especially in front ; the ischium 

 slender, and directed backward. 



(8) The pubis extended forward, and its posterior branch 

 was wanting. 



(9) The limbs w r ere short and massive, and all four were 

 used in locomotion. 



(10) The feet w r ere all provided with broad hoofs, as in 

 Stegosaurus. 



(11) The bones of the skeleton all appear to have been solid. 



(12) Dermal ossifications were present, and some species 

 were protected by heavy armor. 



♦This Journal, vol. xxxvii, p. 336, April, 1889. 



