BIRDS WITH TEETH. 29 



vis, which are firmly fused together, have their posterior extremities free, as in the 

 emu and in Tinamus. 



As the legs of the ostriches have been extremely modified, in order to adapt them 

 for swift movements on terra tirma, so were those of Hesperornis specialized for a life 

 more completely aquatic than that of any known bird. Professor Marsh thinks that 

 it might even be questioned whether it could be said to walk on laud, though admit- 

 ting that some movement on shore was a necessity. Considering the posterior limb 

 as a whole, it will be found a nearly perfect piece of machinery for propulsion through 

 the water. Provisions were made for a very powerful backward stroke, followed by a 

 quick recovery, with little loss by resistance, a movement quite analogous to the strong 

 stroke of an oar feathered 

 on its return. 



To a certain degree the 

 legs of Hesperornis may be 

 said to resemble those of the grebes, though 

 the differences are both many and impor- 

 tant. The thigh bone is shorter and stouter 

 than in any known aquatic bird, recent or 

 fossil, and is very much flattened trans- 

 versely, being considerably broader than 

 thick. The fourth trochanter (Dollo) is 

 plainly visible on the figure. The leg bone 

 is much the largest bone in the skeleton ; 

 the cnemial process rises into a powerful 

 tuberosity above the articulation with the 

 thigh bone. The patella, or knee-pan, is a 

 large separate bone, perforated by a large 

 hole for the tendon of the ambiens muscle. 

 The second, third, and fourth metatarsals 

 were thoroughly fused together, as in all 

 recent birds except the penguins, but in 

 most specimens traces of the sutures remain. 

 The fourth metatarsal so greatly exceeded 

 the other two in size that it forms by far 



the greatest part of the entire tarSO-meta- FIG. 16. Restoration of Hesperornis regalis. 



tarsal bone. The first metatarsal was only 



a mere remnant, united to the lower half of the second by cartilage. The number of 

 toes were four, all directed forward, as in the penguins, and the number of the pha- 

 langes seems to have been normal, viz., 2, 3, 4, 5, of which the penultimate one was the 

 longest, the phalanges on the whole being shorter and thicker than in most swimming 

 birds. The fourth or outer toe was much the longest, being in fact the dominant one, 

 three or four times as powerful as the adjoining middle one, or, indeed, as the other 

 three combined ; these were gradually diminishing in length to the hallux. 



As to the restoration of this remarkable bird, as represented in Fig. 16, little is to 

 be said, as only a few unimportant bones are missing, so that we here have a nearly 

 complete representation of the entire skeleton. Hesperornis regalis was about six 

 feet long, and, when standing in the position represented in our figure, would be rather 

 more than three feet in height, thus considerably surpassing the largest pelican. It is 



