MATERIAL FOR STUDY . 
17 
Fig. 24.—A Sea-urchin. Part of the spines have been removed. 
sand-hoppers, are easily collected by overturning rocks 
left by the tide. 
Compare with 
shrimps. Collect 
also hermit-crabs. 
Marine Fish. 
Where there are 
conveniences for 
salt-water animals, 
a few small marine 
fish may be kept. 
No special direc¬ 
tions are necessary. 
Compare with 
other specimens of 
fish and use with 
Chapter XVI Fig. 23.—A Starfish. After Agassiz. 
THE PREPARATION AND CARE OF SPECIMENS. 
Prepared Specimens. In addition to living animals 
it is always necessary to have at hand a plentiful supply 
