IN FEATHERS AND FUR. 
261 
spines and delicate shells, live on vegetable food, and hide in the 
sand. They are somewhat in the shape of a heart 
In some of the hot parts of the world, Urchins are found of a 
jet black color. They live among the rocks, and are very pugna- 
cious, inflicting painful wounds with their sharp spines. It seems 
almost as if they could dart the spines out, for one naturalist tells 
that when he approached one, he found his hand full of them, 
and they were barbed at the end, so that when he pulled them out 
the head remained in the wound. When he came near the crea- 
tures, they would give an irritable shake to their spines, as though 
to warn him away. 
One of the Urchins is called the Cake Urchin, because he is 
so flat, and another the Wheel Urchin, because on one side he has 
what looks like the square teeth of a cog-wheel, and on the other 
side the teeth are marked out, but apparently, not yet cut. 
