A STUDY OF BONES. 61 



crow, the vertebrae composing the tail-bone 

 are few in number, and are soldered together 

 immovably in the adult form. It was not 

 always so, however, with ancestral birds. 

 The earliest known member of the class 

 the famous fossil bird of the Solenhofen litho- 

 graphic stone retained throughout its whole 

 life a long flexible tail, composed of twenty 

 unwelded vertebrae, each of which bore a 

 single pair of quill-feathers, the predecessors 

 of our modern pigeon's train. There are 

 many other marked reptilian peculiarities in 

 this primitive oolitic bird ; and it apparently 

 possessed true teeth in its jaws, as its later 

 cretaceous kinsmen discovered by Professor 

 Marsh undoubtedly did. When we compare 

 side by side those real flying dragons, the 

 Pterodactyls, together with the very bird- 

 like Deinosaurians, on the one hand, and 

 these early toothed and lizard-tailed birds on 

 the other, we can have no reasonable doubt 

 in deciding that our own sparrows and swal- 

 lows are the remote feathered descendants 



