114 GLAUCUS ; OR, 
such a one as sea-beasts love to haunt. Its weed- 
covered surface shows that the surge has not shifted 
it for years past. It lies on other boulders clear of 
sand and mud, so that there is no fear of dead sea- 
weed having lodged and decayed under it. destruc- 
tive to animal life. We can see dark crannies 
and caves beneath; yet too narrow to allow the 
surge to wash in, and keep the surface clean. It 
will be a fine menagerie of Nereus, if we can but 
turn it. 
Now the crowbar is well under it; heave, and 
with a will; and so, after five minutes’ tugging, 
propping, slipping, and splashing, the boulder gra- 
dually tips over, and we rush greedily upon the spoil. 
A muddy dripping surface it is, truly, full of 
cracks and hollows, uninviting enough at first sight: 
let us look it round leisurely, to see if there are not 
materials enough there for an hour’s lecture. 
The first object which strikes the eye is probably 
a group of milk-white slugs, from two to six inches 
long, cuddling snugly together (Plate IX. fig. 1). 
You try to pull them off, and find that they give 
