1904] Grasping Power of Manus of Ornith. Altus. 35 



strength at this point. Both these phalanges are laterally com- 

 pressed and have deep excavations, in the form of round pits, on 

 either side of their distal ends. These pits are more decided on 

 one side ihan on the other. 



The ungual phalanx (fig. 3) is deep proximally, is much com- 

 pressed laterally and terminates in front in a sharp point that is 

 directed downward when the articular face is in a vertical position. 

 A well-marked claw groove extends, on either side from the upper 

 border at the apex, backward for about two-thirds of the length 

 where it bifurcates, the upper groove reaching the articular surface 

 below the upper border, the lower and deeper one passing down- 

 ward behind a roughened enlargement of the lower surface for 

 the attachment of the flexor tendon. The bone is rough also on 

 the sides and upper border for a short distance in advance of 

 the articular face. This face is vertically concave with a moder- 

 ately well defined median keel extending from the lower to the 

 upper margin. 



Besides the phalanges of the second digit figured, the corres- 

 ponding ones of the other manus were also obtained, as well as a 

 few, including distal ones, belonging to other digits, all presum- 

 ably of the same individual. The additional ungual phalanges 

 are smaller than that of the second digit, are broader in propor- 

 tion to their length and not so deep (see fig. 7). 



In the original description of Oiniithomhnus alitis reference is 

 made to the phalanges above described as well as to the distal 

 end of the interrupted first metacarpal, all found within a few feet 

 of each other in the Red Deer river district of Alberta (Belly 

 river series). 



Figure 5 indicates the amount of rotation possible of 

 the second and distal phalanges round the proximal phalanx. 

 Tr-is IS principally due to the extensive development of the distal 

 articular surface of the proximal phalanx and is suggestive of 

 great grasping power. 



It may be surmised that Ornithomimns altiis was capable of 

 rapid motion in pursuit of prey which it had the power of tena- 

 ciously grasping with its fore limbs. The claws covering the 

 terminal phalanges of the manus were evidently both long and 

 sharp. 



