THE CRETACEOUS PERIOD; 



291 



four are amalgamated to form a flat terminal mass, there being 

 at the same time clear indications that the tail was capable 

 of up and down movement in a vertical plane, this prob- 

 ably fitting it to serve as a swimming-paddle or rudder. The 

 legs were powerfully constructed, and the feet were adapted to 

 assist the bird in rapid motion through the water. The known 

 remains of Hesperornis regalis prove it to have been a swim- 

 ming and diving bird, of larger dimensions than any of the 

 aquatic members of the class of Birds with which we are ac- 

 quainted at the present day. It appears to have stood between 

 five and six feet high, and its inability to fly is fully compen- 

 sated for by the numerous adaptations of its structure to a 



Fig. 212. Toothed Birds (Odontomithea} of the Cretaceous Rocks of America, a, 

 Left lower jaw of Ichthyornis dispar, slightly enlarged ; b, Left lower jaw of ffeaperor- 

 nls regalia, reduced to nearly one-fourth of the natural size ; c. Cervical vertebra of 

 Ichthyornis dispar, front view, twice the natural size ; c', Side view of the same ; d, 

 Tooth of Hesperornis reyalis, enlarged to twice the natural size. (After Marsh.) . 



watery life. Its teeth prove it to have been carnivorous in its 

 habits, and it probably lived upon fishes. It is a curious fact 

 that two Birds agreeing with one another in the wholly abnor- 

 mal character of possessing teeth, and in other respects so 

 entirely different, should, like Ichthyornis and Hesperuniis, 

 have lived not only in the some geological period, but also in 

 the same geographical area; and it is equally curious that 

 the area inhabited by these toothed Birds should at the same 



