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THE POPULAR SCIENCE MONTHLY. 



fact was actually so; that reptiles once existed which walked upon 

 their hind-legs as birds now do. The diagram is a faithful and accu- 

 rate representation of an existing fossil except for this, that, whereas 

 in the existing fossil the bones are twisted about and out of place, I 



Fig. 7. Compsognathus Longipes. (Wagner.) 



have put them here in the position that they must have had in na- 

 ture. You see a creature with a long neck and bird-like head, with 

 very small anterior extremities, and that compsognathoits creature 

 must assuredly have walked about upon its hind-legs, bird-fashion. 

 Acid to this feathers, and the transition would be complete. Now 

 to define it : The possession of teeth would, as we see, not separate 

 this animal from the class of birds we have. We have had to stretch 

 the class of birds so as to include birds possessed of teeth, and, so far 

 as the character of the skeleton goes, we may fairly say that there 

 needs here little more than the addition of feathers and whether this 

 creature had them or not we don't know to convert it into a bird. 



I have said that there can be no question, from their anatomical 

 structure, that these animals walked upon their hind-legs, and, in fact, 

 there are to be found in the Wealden strata of England gigantic foot- 

 steps arranged in order like these of the Brontozoum, and which there 

 can be no reasonable doubt were made by Dinosmiria, the remains 

 of which were found in the same rock. And, knowing that reptiles 

 that walked upon their legs and shared many of the anatomical char- 

 acters of birds did once exist, it becomes a very important question 

 whether those tracks in Massachusetts to which I referred just now, 

 and which formerly used to be unhesitatingly ascribed to birds may 

 not all have been made either by reptiles similar to the Dinosauria, 

 or whether, if we could get hold of the skeleton which made these 



