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READING RIDDLES OF THE ROCKS 121 
For the adjustment of the muscles is depend- 
ent on the structure of the skeleton, and put- 
ting on the muscles means blocking out the 
form, details of external appearance being sup- 
plied by the skin and its accessories of hair, 
scales, or horns. Let us suppose in the present 
instance that we are dealing with one of the 
great reptiles known as Triceratops whose re- 
mains are among the treasures of the National 
| Museum at Washington, for the reconstruc- 
_ tion of the big beast well illustrates the meth- 
ods of the paleontologist and also the troubles 
by which he is beset. Moreover, this is not a 
purely imaginary case, but one that is very © 
real, for the skeleton of this animal which was 
shown at Buffalo was restored in papier-maché 
in exactly the manner indicated. We have a 
goodly number of bones, but by no means an 
entire skeleton, and yet we wish to complete 
the skeleton and incidentally to form some 
idea of the creature’s habits. Now we can in- 
terpret the past only by a knowledge of the 
present, and it is by carefully: studying the 
skeletons of the animals of to-day that we can 
learn to read the meaning of the symbols of 
