57 



Breadth of first molar 14| Hues. 



Width of first molar 14^ lines. 



Breadth of second molar 16 lines. 



Width of second molar 16 lines. 



Breadth of last molar 19j lines. 



Width of last molar • 18 lines. 



Width of palate between canines 28 lines. 



Width of canine alveoli lines. 



Palseosyops JUNIUS. 



Dr. Carter recently sent the writer several small fragments of the right 

 side of a lower jaw, together with a sketch of a larger fragment of the left 

 side, containing the last premolar and the succeeding molars. The speci- 

 mens were obtained from the Bridger beds, and appear to indicate a small 

 species of Palseosyops, though it- is not improbable that they pertain to a 

 small variety of P. paiudosus. 



The parts agree closely with the corresponding parts of the lower jaw and 

 teeth of the latter, except in size. They have been viewed as representatives 

 of a species with the name of Palceosyops Junius. 



The measurements of the teeth in comparison with those of P. paiudosus 

 are as follows : 



Space occupied by the last premolar and molars 



Space occupied by the molars 



Breadth of last premolar 



Thickness of last premolar 



Breadth of first molar 



Breadth of second molar 



Breadth of third molar 



Thickness of third molar at middle 



Palseosyops 



Palseosyops 



jimius. 



paiudosus. 



Lines. 



Linc.t. 



48 



55 



;;!>.', 



46 



8 



9 



5i 



H 



10 



124 



12 



15 



17 



19 



7 



n 



LIMNOHYUS. 



This genus was originally named by Professor Marsh, in a communication 

 published in the American Journal of Science for August, 1872, and was 

 applied to Palseosyops under the misapprehension that this genus had not 

 been distinguished by the possession of one or two cones to the inner part of 

 the crown of the last upper molar tooth. As it was as clearly demonstrated 

 as the nature of the specimens would admit, that the last upper molars of 

 8 G 



