704 THE BKIDGEK FAUNA, 



are strongly inflected, and have a low median rib. Each internal cusp 

 sends a low ridge outwards and forwards, and the anterior intermediate 

 tubercle is distinct. The crowns have strong anterior and posterior cingula, 

 but no internal cingula. The ledge that connects the inner cusps in P. 

 major is represented by a tubercle in this species. The posterior cingulum 

 of the last molar rises to a prominent ridge on the inner posterior margin 

 of the crown. In a third premolar the anterior and posterior cingula do 

 not connect on the inner side of the crown. The external cusps have a 

 nearly vertical external wall, and are well distinguished ; the anterior one 

 only has a median rib. It has no external cingulum. There is a weak 

 one on the true molars. The enamel is smooth where worn ; on unworn 

 surfaces it is somewhat wrinkled. 



Measurements of teeth. 



Length of true molar series 0.063 



Diameters of first true molar 5 ^"t^^P^^^"™"" °1^ 



transverse 020 



c anteroposterior 013 



Diameters of third premolar I ^^^^^^^^^ p^g 



The shaft of the radius is not very stout, and shows a groove for con- 

 tact with the ulna below. The carpal articular face is wide and depressed, 

 and without trace of scapholunar ridge. A small part of both surfaces is 

 recurved inferiorly, and each part is followed by a shallow fossa: these are 

 separated by a low tuberosity. The cviboid has a rather short posterior 

 extension, whose superior surface makes with the transverse anterior surface 

 an L of branches of equal length. Below, the magnum and unciform facets 

 are strongly concave, the latter a little the larger. No posterior tuberosity. 

 The proximal phalange is longer than wide, and stout and flat. 



Measurements. 



M. 



Width of carpal facet of radius -j.. 0.03O 



Diameter (transverse) of radius at middle 018 



I vertical 020 



Diameters of os lunare 1 transverse above 017 



' anteroposterior 020 



longitudinal 023 



transverse 017 



Diameters of phalange } 



The above fragments were cut from a single small block of matrix. 

 The P. junior, according to Leidy, differs in the character of its supe- 



