Peterson: Miocene Beds of Nebraska and Wyoming. 27 



important characters enumerated above are the greater vertical diameter 

 of the cranium in P. carrikeri, which is due to the greater elevation 

 of the region back of the orbit. The temporal ridges and the sagittal 

 crest are very prominent, and the zygomatic arch extends downward 

 in a manner suggestive of Elotherium. 



The vertical diameter of the skull is not greater than that in P. 

 chelydra, except as it is increased by the elevation of the occiput and 

 the downward thrust of the zygoma. The group of three skeletons in 

 the Hall of Vertebrate Paleontology is mounted in the original posi- 

 tion in which the animals were found in the field. The specimens are 

 among the most interesting collected by the writer and will be more 

 fully described in a later publication. 



Measurements. 



mm. 



Greatest length of the skull 316 



Length from anterior border of orbit 'to tip of nasals 152 



Length from anterior border of orbit to the occipital condyles 174 



Length of alveolar border 175 



Distance from Mi to the occipital condyle 132 



Greatest transverse diameter of the skull 295 



Transverse diameter of the occipital condyles 67 



Greatest transverse diameter of brain cavity 85 



Transverse diameter of muzzle at base of canine . 104 



Antero-posterior diameter of the orbit 35 



Vertical diameter of the orbit 35 



Greatest vertical diameter of the zygomatic arch 165 



Vertical diameter of jugal below middle of orbit 40 



Length of superior dentition 175 



Distance from incisors to Mi 105 



Length of molar series 75 



Antero-posterior diameter of canine near base 16 



Transverse diameter of canine near base 19 



Antero-posterior diameter of P 1 16 



Antero posterior diameter of P^ 18 



Antero-posterior diameter of P^ 18 



Antero-posterior diameter of Pi 16 



Antero-posterior diameter of Mi ... 22 



Antero-posterior diameter of M^ 24 



Antero-posterior diameter of M^ 32 



Length of mandible 255 



Length of alveolar border of mandible 183 



Vertical diameter of angle at the condyle 120 



Vertical diameter of angle at the coronoid process 118 



Vertical diameter of mandible at M^ 58 



