5 



Dysganus bicarinatus, sp. no v. 



This dinosaurian is represented in the collections by some of the 

 teeth of three individuals. Two of the teeth represent immature 

 stages, while the others are worn by continued use. They all 

 present characters not found in the D. encaustics, from which they 

 differ in a direction the opposite of that which characterizes the 

 D. liaydenianus. 



The crowns present a nearly flat face without incurved lateral 

 angles, nor prominent median keel. The basis is wide, projects in 

 a rim beyond the face, and is invested with rough cementum. The 

 face is peculiar in being divided into three planes by two low 

 angular ridges, and its surface is smooth. The dentinal column 

 is triangular, and there are two posterior columns separated by a 

 fissure, in mature teeth. 



The absence of the lateral incurved angle, and the presence of 

 the two median ones distinguish this species from the D. encaustus. 



Measurements. m. 



Length of basis 009 



Width " Oil 



Length of worn face .006 



( anteroposterior .... .011 



Diameter of crown { . Ar ,„ 



( transverse 007 



Dysganus peiganus, sp. no v. 



In the typical tooth of this species the form approaches the 

 genus Paleeoscincus, Leidy, in the compression of the crown, and 

 the contraction of the base; it is a limital species of Dysganus if 

 realty properly placed in that genus. 



The widest portion of the crown is above the base ; from this 

 expansion it contracts in both directions, and in the unworn tooth 

 forms an angular median apex. This is not the case in D. encaustus, 

 which is regularly rounded. The margin of the crown is narrowed, 

 expanding but little towards the expansion, and is quite rugose. 

 From these rugosities low ridges descend on the face of the tooth, 

 whose surface is also minutely rugose. The face is divided by a 

 prominent median rib, which extends to the apex. No cementum 

 is visible on the basis, in the only specimen in which this part is 



preserved. 



Measurements. m. 



Length of crown 008 



{transverse 005 

 anteroposterior i at base • • - 008 

 l greatest . . .011 



