38 



but has a straight posterior basal ridge. Its forward edge is 

 worn so as to expose a small tract of dentine. The second is 

 larger, but very much like the first in conformation ; while the 

 third has an acute conical crown with a strong basal ridge. 



Of the premolars the first is wanting in this specimen. 

 The second is bilobed, the anterior lobe much the larger. It 

 has a small accessory tubercle on its anterior slope. The 

 outer face is rounded, the inner nearly flat. The posterior 

 lobe is very small and obtuse, and with the inner face slightly 

 grooved. In third and fourth the valley between the lobes 

 and the groove on their faces enlarge ; while the anterior lobe 

 becomes relatively smaller, 



Measurements of Lower Jaw. 



M. 



Diastema between canine and first premolar -024 



Length of entire molar series - -143 



Distance between last molar and extremity of angle -147 



Depth of jaw at last molar -070 



Among the first discoveries on Cotton wood Creek, in con- 

 nection with the lower jaw of P. paludosus just described, 

 were an ulna and radius, and part of the manus and scapula 

 of the same. These have been figured, together with other 

 fragments belonging to the same species, in Plate III., and 

 form an interesting complement to the nearly complete hind 

 limb of P. major previously described. 



The scapula has a shallow oval glenoid cavity, which is 

 concave longitudinally. Separated from it by a narrow notch 

 is a strongly recurved coracoid, placed on the inner side of 

 the bone. Above the coracoid the border is thin, and arches 

 inwards and then forwards ; while the glenoid border is much 

 straighter, rising from a slight tuberosity. The spine rises 

 gradually from the glenoid, and does not bear any indication 

 of an acromion. 



The humerus is represented by proximal and distal ex- 

 tremities. The latter presents the same characters on a 

 smaller scale as in P. major. Upon the proximal end there 

 is a deep bicipital groove. The greater tuberosity has a 

 hooked anterior projection, and runs back into a ridge be- 

 hind. (See Fig 7, Plate III.) 



