READING RIDDLES OF THE ROCKS 127 
creature as he was or may have been in life, 
is, to be honest, very largely guesswork, 
though to make a guess that shall come any- 
where near the mark not only demands a 
thorough knowledge of anatomy —for the 
basis of all restoration must be the skeleton — 
but calls for more than a passing acquaintance 
with the external appearance of living animals. 
_And while there is nothing in the bones to 
tell how an animal is, or was, clad, they will at 
least show to what group the creature be- 
longed, and, that known, there are certain 
probabilities in the case. A bird, for example, 
would certainly be clad in feathers. Going a 
little farther, we might be pretty sure that 
the feathers of a water-fowl would be thick 
and close; those of strictly terrestrial birds, 
such as the ostrich and other flightless forms, 
lax and long. ‘These as general propositions ; 
of course, in special cases, one might easily 
come to grief, as in dealing with birds like 
_ penguins, which are particularly adapted for 
an aquatic life, and have the feathers highly 
modified. ‘These birds depend upon their fat, 
and not on their feathers, for warmth, and so 
