524 O. C. Marsh — Notice of New Tertiary Mammals. 



The skull measures twenty-eight inches from the front of 

 the nasals to the back of the occipital condyles, and twenty- 

 four inches in greatest width across the zygomatic arches. 

 The space occupied by the upper dental series is thirteen and 

 one-half inches, and by the true molars, eight inches. 



Teleodus avus, gen. et sp. nov. 



The present genus is allied to Brontotherium, but differs 

 from it in having six lower incisors instead of four. It has 

 the same number of inferior premolars and molars, and these 

 teeth are similar in the two genera. From Diplacodon of the 

 Upper Eocene, the present genus may be distinguished by 

 having only three lower premolars on a side instead of four. 

 The type-specimen indicates an old animal, somewhat smaller 

 than Brontotherhom gtgas. 



Of the three lower incisors in place on each side, the middle 

 one is the largest. There is a short diastema behind the lower 

 canine, but no first premolar. The dental formula of the lower 

 jaws is as follows : 



Incisors, 3 ; canine, 1 ; premolars, 3 ; molars, 3. 



The, space occupied by the lower dental series is fourteen and 

 one-half inches, and by the last three molars, eight and one-half 

 inches, 



Colodon luxatus, gen. et sp. nov. 



The present genus appears to be nearly allied to Zophiodon, 

 but may be distinguished from it by the upper premolars 

 having two inner cones, and by the absence of canines in the 

 lower jaws. The upper and lower true molars are of the same 

 general structure as those of Bophiodon. From Hyrachyus, 

 of the Eocene, the upper premolars, the absence of canines 

 below, and the last lower molar with a posterior lobe, will sepa- 

 rate it. The present genus is probably a lineal descendant of 

 the Eocene Helatetes, and an intermediate form between that 

 genus and Tqpiravus of the Pliocene. The lower dental 

 series has the following formula : 



Incisors, 3 ; canine, ; premolars, 3 ; molars, 3. 



This series occupies in the type-specimen a space of five and 

 one-half inches, and the last three lower molars, two inches.' 



Hyopotamus deflectus, sp. nov. 



A second American species of the genus Hyopotamus is 

 indicated by the greater portion of a skull with lower jaws, 

 recently found in the Miocene of Dakota. These belonged to 

 an animal about the size of Ilyopotamus Americanus, Leidy, 

 of which teeth only are known. 



