COPE.] 



PALEONTOLOGY LOUP FORK EPOCH. 527 



navicidare is shallow and concave proximally. The ecfocuneiforme is of 

 similar length; behind it a well-developed mesocuneiforme, which sup- 

 ports the internal metatarsal. The external metatarsals are situated 

 behind the median, except for an inch at their distal extremities. Their 

 articular surfaces are compressed, and present an obtuse trochlear angle, 

 but no keel ; they reach to the base of the condyle of the median meta- 

 tarsal behind. The latter is very convex above, slightly flattened be- 

 low. The lateral digits only reach to the distal end of the first phalanx. 

 The penultimate phalanx of each is much produced behind; the last 

 or ungueal is much comjDressed, and is literally a half-hoof. The coro- 

 net is half as long as the pastern, and the unguis or coffin-bone is 

 acuminate in outline and elevated on the middle line. It is deeply fis- 

 sured at the extremity, and the margin abounds in foramina. The nu- 

 tritious foramina of the base are each in the apex of a triangular fossa, 

 which is open posteriorly. This bone has proportions not unlilve those 

 ascribed by Leidy to a specimen from the Niobrara, but is rather smaller; 

 but the foot to which it pertains measures but 10.5 inches, while that of 

 P. sejmictus (without tarsals) is 11 inches in length. 



Measurements. 



M. 



Length of atlas, (extreme) O.OGl 



Width of atlas medially below - .035 



Width of atlas in front of diapophyses : .060 



Length of odontoid process .023 



Length of three posterior dorsal vertebrae .076 



Diameter of articular face of centrum of vertebrae } ^^Jl^^^^]^^ '^il 



Length of humerus, (axial) .192 



Diameter of pro.i.ai end| -^^jj^-;:;; ;:;:;;;:::;;;-::;::: I;::;; :»g 



Diameter of condyles .044 



Length of radius : .229 



( proximally .045 



Transverse diameter of radiu8< at middle .026 



( distally 038 



(proximally .026 



Antero-posterior diameter of radius < medially .018 



( distally 023 



Diameter of femur^ ^5^5li;; ?io 



I condyles , ,058 



Length of tibia .250 



Length of foot, including tarsus .325 



Length of foot without tarsus .277 



Outside length of calcaneum ,075 



Depth of calcaneum behind .027 



Width in front 033 



Total length of astragalus ,045 



Total width 041 



Width oftrochlea of astragalus .018 



Width of navicular facet .022 



Depth of navicular facet .022 



Width of cuboid facet 008 



Width of cuboid bone fore and aft : . ^ .023 



Length of cuboid bone .015 



Length of internal metatarsus ,170 



Transverse width of trochlea of median metatarsus .021 



Length of ijastern .042 



Width of pastern proximally ,025 



Length of coronet .027 



Width proximally ,025 



Length of coffin 0.16 



Width of articular face * .021 



Width between angles ,0:>U 



Elevation behind .023 



