92 



by the fragments above, described, but arc nearly as thick; and the retained 

 tooth is of the same size and form as its fellow in the fragments of older jaws. 



One of the rami contains the fangs of the complete molar scries, together 

 with part of the canine alveolus, which is close to the former. The number 

 of premolars I cannot determine with certainty. If three, the first of the 

 series is larger than the second, and has its fangs more widely separated. If 

 the number is four, the anterior two have each a single fang. 



Perhaps the latter is the true condition, which accords with that attributed 

 to Limnotherium by Professor Marsh. 



Three vasculo-neural foramina are situated at the outer part of the ramus: 

 one just back of the position of the canine alveolus ; a second below the 

 interval of the back two premolars, and the third beneath the first molar. In 

 the opposite ramus the latter is below the last premolar, and it occupies the 

 same position in the former two specimens. 



The first molar tooth retained in one of the rami agrees with the descrip- 

 tion of those in the older jaw-fragments. Fig. 38, Plate VI, represents the 

 right second molar much worn ; and Fig. 39 represents the first left molar 

 in a much less abraded condition. 



Measurements from the two rami of the lower jaw just described are as 

 follows : 



Lines. 



Space occupied by the premolar and molar series 1G.J 



Space occupied by the molar series 9 



Depth of jaw below the premolars 5 



Depth of jaw below the middle molar 4f 



Breadth of the first molar 3 



Width of the first molar .• 2£ 



Figs. 1, 2, Plate XXVII, represent a specimen of a tooth recently discov- 

 ered by Dr. Carter on Grrizzly Buttes. It appears to be a first upper true 

 molar of Hipjwsyus formosus, and is scarcely worn. It was found isolated 

 and unaccompanied by any other pieces which could be reasonably attributed 

 to the same animal. From the comparative perfection of its crown, its con- 

 stitution is more evident. It resembles in miniature the corresponding teeth 

 of Anchitherium, and differs especially in the less proportionate development 

 of the median lobes of the crown, in the greater degree of production of the 

 basal ridge, in the more intimate union of the inner lobes and their more 

 sloping character externally, in the more isolated condition of the postero- 

 median lobe from the contiguous inner one, and in the more wrinkled condi- 



