114 COMPAEATIVE DENTAL ANATOMY 



teeth in distinct sockets. Another gronp were 

 very large swimming birds, and had teeth set in 

 grooves. In Ichthyornis, the teeth are about 

 twenty-two in each jaw, all sharp and recurved, 

 with crowns flattened and covered with enamel. 

 In Hesperomis the teeth were also socketed. The 

 group presents a regular gradation from groove 

 to socket in the methods of attachment of the 

 teeth. The forms of these teeth are of distinctly 

 reptilian type, and indicate the link between birds 

 and reptiles. 



