212 



FIRST LESSONS IN ZOOLOGY. 



which is a connecting link between the birds and rep- 

 tiles, not only in the shape of certain bones, but from its 

 having teeth and a long vertebrated tail. After this 

 strange form, half reptile and half bird, had passed away, 



FIG. 219. Birds with teeth. Below, two Hesperornis; above is an 



Ichthyornis. 



it was succeeded by birds with teeth. Of these, the most 

 notable was the wingless diving-bird, called Hesperornis, 

 and a gull-like swiftly-flying bird, with teeth implanted in 

 sockets, the Ichthyornis (Fig. 219). The former was prob- 

 ably the forerunner of the birds with a keelless breastbone, 



