F. B. Loomis—New Mosasaur from the Ft. Pierre. 565 



side, so that in an end view the articular surface is broadly tri- 

 angular. The distal end is rounded and but slightly thickened. 

 The anterior border is the longer, both it and the posterior 

 border being moderately concave. 



The ulna is the small forearm bone, its upper end being 

 considerably but uniformly thickened. Distally the articular 

 surface is divided into two parts which meet each other in an 

 obtuse angle. 



One of the specimens which was found was an approximately 



Fig. 8. 



Fig. 8. The anterior paddle seen from the inner surface. 1/6 nat. size. 



complete paddle with 6 carpal bones, the metacarpals and pha- 

 langes all in place. In fig. 8 these carpals are drawn as they 

 were found, except that the sixth, which lay above the one 

 marked X and was like it including the notch, has been omitted 

 as being either an extra, or at least out of place. All these 

 carpals are probably too far toward the radial side. It is 

 unusual for Platecarpus to have more than four carpals, but 

 it is apparently a feature of this species. The metacarpals are 



