206 THE STORY OF BIRD-LIFE. 



Berlin specimen, the head, pectoral girdle, and 

 the wings, are beautifully preserved; so also is 

 the tail. 



This tail, as is well seen in the figure, is the 

 most remarkable feature of the whole bird. It 

 is like that of no other bird known. But it ex- 

 actly resembles the tail of a reptile. It is of 

 great length, and composed of a number of separate 

 vertebrae, each of which supports a pair of long 

 tail-feathers. 



This method of disposal of the tail-feathers is 

 found in no other known bird, fossil or living. 

 The accompanying figures show the nature of the 

 two different forms of arrangement. Fig. A shows 

 the tail of ArcJmopteryx ; fig. C, that of modern 

 birds. In Archceopteryx the feathers are dis- 

 tributed along the vertebrae like the arrangement 

 of flowers along a stem, to form what is known 

 as a spike. In other birds they are clustered 

 around a common centre, as in a composite 

 flower. The tail has been telescoped, as it 

 were, so as to cause the bases of the feathers to 

 cluster together, or to radiate from a common 

 centre. 



The possession of teeth in the jaws is another 

 reptilian character, but, as we shall see, birds re- 

 tained these long after they had changed the form 

 of the tail. Finally, the teeth disappeared. 



The wing of archceopteryx differed from that of 

 all other birds in that the third digit was armed 

 with a claw, as also were the thumb (or first digit) 

 and the first finger (or second digit). Claws on 

 the thumb and index finger occur frequently in 

 birds of to-day. 



