BIRDS. 



425 



of this old-fashioned form teeth do occur, and are planted in the jaws, 

 almost exactly as in some of the reptiles. Here, then, is one of the forms 

 which may be said to partially close the gap between the existing reptiles 

 and birds, and yet this form is 

 distinctly a bird. The only speci- 

 mens known have been found in 

 the large quarries of lithographic 

 stone at Solenhofen, in Bavaria. 

 These are the oldest known re- 

 mains of birds, the rocks in which 

 they occur being of Jurassic age. 

 The specimen figured was about 

 as large as a crow ; another has 

 been found considerably larger. 



Our own country also has its 

 fossil birds ; forms nearly as 

 strange as the one just men- 

 tioned, but of which we know 

 far more than we do of that, 

 owing to the excellent preserva- 

 tion of the remains. These, too, 

 were birds with teeth, but they 

 lacked the long tail of their older 

 European relative. Of these 

 birds two very distinct forms 



are known. One had the teeth implanted in sockets in the jaws, and in 

 this and in many respects was so like a reptile, that if one did not have 

 other parts of the skeleton, he would be as likely to class it among that 

 group as among the birds. This form is known as Ichthyornis (the fish- 

 bird) ; it was about the size of a pigeon, and had a tail much like that of 

 modern birds. Its strong wings would indicate that in its habits it was 

 much like the terns and gulls of the present day. 



The other form, Hesperomis (the bird of the west) was even more 

 strange, for it was actually a bird without wings ; and Professor Marsh 

 even has his doubts whether it could walk upon the land. On the con- 

 trary, he regards it as having been far more aquatic in its habits than even 

 the penguins of to-day. It was well adapted for a life of swimming and 

 diving. Its legs and feet formed admirable paddles, and the bones show- 

 that it must have had strong muscles to move them ; while the bones of 

 the tail, flattened from above, would indicate that that organ was also 

 of use in swimming, and must have been shaped much like that of a 



Fig. 364. — The oldest known bird (Arrhsenpteryx). The 

 peculiar tail is most noticeable in this specimen. 



