READING THE RIDDLES OF THE ROCKS 109 



the salamanders among batrachians, are clothed in 

 smooth, shiny skin. There might, however, be reason 

 to suspect that a creature largely aquatic in its habits 

 did occasionally venture on land, as, for instance, 

 when vertebrae that seem illy adapted for carrying the 

 weight of a land animal are found in company with 

 huge limb-bones and massive feet we may feel reason- 

 ably certain that their owner passed at least a portion 

 of his time on terra firma. 



So much for the probabilities as to the covering of 

 animals known to us only by their fossil remains; but 

 it is often possible to go beyond this, and to state 

 certainly how they were clad. For while the chances are 

 small that any trace of the covering of an extinct animal, 

 other than bony plates, will be preserved. Nature does 

 now and then seem to have relented, and occasionally 

 some animal settled to rest where it was so quickly 

 and quietly covered with fine mud that the impression 

 of small scales, feathers, or even smooth skin, was pre- 

 served; curiously enough, there seems to be scarcely 

 any record of the imprint of hair. Then, too, it is to be 

 remembered that while the chances were very much 

 against such preservation, in the thousands or millions 

 of times creatures died the millionth chance might come 

 uppermost. 



Silhouettes of those marine reptiles, the Ichthyosaurs, 

 have been found, probably made by the slow carboniza- 

 tion of animal matter, showing not only the form of the 

 body and tail, but revealing the existence of an unsus- 

 pected back fin. And yet these animals were apparently 

 ilad in a skin as thin and smooth as that of a whale, 

 [mpressions of feathers were known long before the dis- 

 iovery of Archaeopteryx ; a few have been found in the 

 jreen River and Florissant shales of Wyoming, and a 

 iesperornis in the collection of the State University 



