82 ANIMALS OF THE PAST 



those of the leg as to turn edgewise as the foot 

 was brought forward and thus to offer the least 

 possible resistance to the water. It is a re- 

 markable fact that the leg bones of Hesperornis 

 are hollow, remarkable because as a rule the 

 bones of aquatic animals are more or less solid, 

 their weight being supported by the water; but 

 those of the great diver were almost as light as 

 if it had dwelt upon the dry land. That it did 

 not dwell there is conclusively shown by its 

 build, and above all by its feet, for the foot of 

 a running bird is modified in quite another 

 way. 



The bird was probably covered with smooth, 

 soft feathers, something like those of an Apte- 

 ryx ; this we know because Professor Williston 

 found a specimen showing the impression of 

 the skin of the lower part of the leg as well as 

 of the feathers that covered the " thigh " and 

 head. While such a covering seems rather in- 

 adequate for a bird of such exclusively aquatic 

 habits as Hesperornis must have been, there 

 seems no getting away from the facts in the 

 case in the shape of Professor Williston's spec- 

 imen, and we have in the Snake Bird, one of 



