40 Annals of the Carnegie Museum. 



Vertical diameter of tympanic bulla 13 



Total length of the dentition 95 



Length of premolar series 35 



Length of molar series 45 



A ntero-posterior diameter of canine at base 6 



Transverse diameter of canine at base 8 



Antero-posterior diameter of Pi 8 



Transverse diameter of Pi 4 



Antero-posterior diameter of P^ 10 



Transverse diameter of P^ 7 



Antero-posterior diameter of P^ 10 



Transverse diameter of P- 3 - 9 



Antero-posterior diameter of P^ 9 



Transverse diameter of P^ 12 



Antero-posterior diameter of Mi 12 



Transverse diameter of M 1 14 



Antero-posterior diameter of M^ 15 



Transverse diameter of M- 15 



Antero-posterior diameter of M^ 19 



Transverse diameter of M^ 16 



Merychyus, sp. indet. 



The specimen (No. 1284) described below was found in the Lower 

 Harrison beds on Squaw Butte, Sioux County, Nebraska. The remains 

 consists of a nearly complete tibia with the middle part of the shaft of 

 the fibula adhering to it ; the astragulus, cuboid, navicular, cuneiform, 

 and the greater part of the metatarsals. 



Inasmuch as no part of the cranium or teeth were found with the 

 specimen the writer hesitates to apply a specific name, though the 

 material may represent a new species. It is provisionally referred to 

 the genus Merychyus. 



The tibia is quite long with a slender shaft ; the cnemial crest is 

 somewhat less developed, and does not reach as low down on the shaft 

 as is the case in Phenacoccelus typus. On the posterior face of the 

 shaft is a prominent ridge which extends from the postero-fibular 

 angle of the proximal end, first obliquely downward, then more 

 directly downward, and disappears 40 mm. from the distal end. This 

 ridge is almost entirely wanting on the tibia of Phenacoccelus typus, 

 while that in Merychyus minimus™ is fairly well developed, but in a 

 less degree than in the present specimen. The internal malleolus is 

 directed vertically downward and the groove for the internal condyle of 



14 To be described later in this paper. 



