A FAR ADVENTURE 305 



portance of small differences in a bird 's skeleton. ' ' 



''Yes, indeed, sir," the boy answered; ''that's 

 what all the classification of Orders practically is 

 based on. ' ' 



"Exactly. Now, if you remember, in that tiny 

 chick you examined under the microscope, one 

 time, that chick we took before it was half hatched, 

 you could see that the tail was made up of six or 

 seven bones, one behind another like a lizard's tail. 

 In the chick we examined that was almost ready to 

 come out of the shell, these six or seven bones had 

 become fused together into a bony plate, on which 

 the feathers would afterwards he supported in the 

 form of a fan. 



"In the Archaeopteryx, when it was full grown, 

 the tail was similar in formation to that which is 

 now to be seen in the unhatched chick, the bones lay 

 one behind each other, they were not compressed 

 into a single bone. As a matter of fact, the tail 

 was very long, in proportion as long as a lizard's 

 tail and much of the same structure. Each bone 

 carried a pair of feathers, one on each side. 



"Now, Shan," the Feather Man continued, 

 "take the question of scales and feathers. A 

 feather, as you know, is only a modified scale, and 

 such a thing as a completely feathered bird does 



