Ichthyornis eg 



similarity of habits. And, as he has further pointed out, the anomalous con- 

 dition would be presented of placing the strong-flying Loons and Grebes in the 

 direct line of descent from a flightless bird, which would be "quite out of the 

 question." All things considered it would appear that Hesperornis was in many 

 respects a very highly specialized type which has been blotted out without 

 leaving any close relatives among living birds. 



Other Forms. In the same beds with Hesperornis regalis, the form above 

 mentioned, two additional 

 species of Hesperornis were 

 described, one of which has 

 recently been removed as 

 the type of a new genus 

 (Hargeria), and another 

 wholly different flightless 

 swimming bird known as 

 Baptornis, or the "plung- 

 ing bird," in allusion to 

 its probable diving habits. 

 These are all imperfectly 

 known, and a full descrip- 

 tion may be omitted. 



Ichthyornis. The 

 second order of Toothed- 

 birds (the Ichthyornithi- 

 formes) differs essentially 

 from the first, as already 

 mentioned, in having the 

 numerous teeth implanted 

 in distinct sockets. They 

 take their name from Ichthy- 

 ornis, the principal genus, 

 which signifies "fish bird," 

 from the fact that the ver- 

 tebrae are of the same shape 

 as in fishes. Although a 



dozen or more nominal species have been described, disposed among five 

 more or less tentative genera, the group is still imperfectly understood. Of 

 the various members Ichthyornis victor is best known and may be selected 

 for brief description. It was a much smaller bird than Hesperornis, being 

 about the size of a common Pigeon, and was clearly a very powerful flyer. 

 The head was relatively much larger than in Hesperornis, but the disposi- 

 tion of the teeth was the same in both, and the component parts of the 

 mandibles were likewise distinct. The teeth were all sharp and pointed, 

 more or less compressed, and strongly recurved, and were placed vertically as 

 in the crocodiles and certain extinct lizards. The exact number of vertebrae 



FlG. 22. Ichthyornis victor, a Cretaceous Toothed-bird of 

 flight, natural size. (Restored by Maish.) 



