G3 



ClONODON STENOPSI8, Cop<'. 



'i'liis 1 )iii()saiir was (liscovcicd by CTeoigc; M. Dawson, ol" Muiit real, geolo- 

 gist of the 15rilish Nortli American Boundary Commission, in (lie Fort Union 

 beds of the IMilk River region. It is represented by fragments oC maxillary 

 hones, with a tew contained pieces of teeth. Probably, several ol'llie numer- 

 ous i)ones of reptiles of this order, obtained by Mr. Dawson, pertain to the 

 same genus and species; but there are as yet no means by which to distin- 

 guish them from other species of Hadrosaurirhc in the collection. 



The maxillaries exhil)it the vertical grooves characteristic of the genus, 

 and the teeth are of the rod-like form of those of the C. arctalus. Cope, and 

 the roots are similarly compressed. An important dift'erence in the teeth is 

 seen in their lack of the carina on the enamel-face of the base of the crown at 

 least ; the apices being in (sach case broken away. Accordingly, the root 

 exhibits no corresponding groove on its inner side, as is the case in C. arcta- 

 tus. The form of the maxillary lione is also characteristic. In C. arctatus, 

 this piece bears a longitudinal protuberance on its inner side so as to have 

 given the face great proportionate width. In C. stenopsh, tiiis j)rotuberance 

 is much less pronounced; the inner face, instead of being nearly horizontal 

 above, is curved abruptly downward, and a shallow horizontal face of no 

 great width replaces the wide oblique cornice which extends from the alveolar 

 border in C. arctatus. The remains indicate a species of the size of C. arc- 

 tatus. 



Measurements. 



M. 



Depth of the maxillary bono on n dental gioovi' 0. 0350 



Diameter of the maxillary bone external to alveoli 0.0200 



Diameter of a tooth 0. 0045 



POLYONAX, Cope. 



Char. gen. — A species considerably larger than tin; last, n;presented 

 by vertebra3 and numerous fragments of linil)-bones. The most characteris- 

 tic of the former are two, probably from the posterior dorsal region, whicli 

 are somewhat distorted by pressure. The more anterior is shorter than the 

 other, and exhibits both articular taces slightly concave; the one more so than 

 the other. They are higher than wide, and the border is scolloped above tor 

 the capitular articulation for the rib. There are num(n-ous nutritious fora- 

 mina, and some ligamentous pits on the articular surtiuies. The inferior 

 face is rounded. In the longer vertebra, both faces are more strongly con- 



