302 THE WORLD OF THE SEA. 
tively slender. At the first glance, it seems impossible that such 
a creature could possibly penetrate a cocoa-nut, surrounded as it 
is by a massive, fibrous covering and protected by a firm, hard 
shell; but M. Liesk, who has often watched the operation, tells us 
that the crab strips off the matted covering, fibre by fibre, always 
beginning at that end where the dimples so characteristic of the 
cocoa-nut shell will be found. When the shell is exposed, it strikes 
it with its great pincer-claws until an opening is made, then, by 
means of the slender claws, it extracts the white contents of the 
nut. This adroitness is another testimony to the instincts of the 
crab tribe. 
The crustaceans have eyes of two kinds, simple and compound. 
The first is sessile and immovable, somewhat protruding, and very 
convex. The other eye is carried upon a short, calcareous stem, 
and is composed of a considerable number of little eyes, sym- 
metrically agglomerated together. It resembles a skull-cap which 
is made up of facets, these being so many distinct eyes. The 
compound eye of the lobster is thus composed of 2,500 eyes. 
The simple eye is myopus, or short sighted, the composite eye 
has a longer range. This wonderful organ is found in the fossils 
of the first crustaceans which lived upon the globe. The charac- 
teristic fossil of the earliest formation of stratified rocks—the 
Silurians—is the 77rzlobitfe, and here is an argument against the 
theory of development, for we find almost the first inhabitant 
of the Paleozoic seas to be in possession of the most highly 
developed eye. 
The crustaceans are endowed with a delicate sense of smell, 
and by this means discover their prey. If a little dead fish be 
placed under a stone in a pool of sea-water, the crabs ensconced in 
the neighbouring hoies will soon make their appearance, attracted 
to the feast by the smell. Many naturalists consider that the sense 
of smell resides in the antenne, and if this be the case, the 
quickness of the sense is explained by the length of the “ feelers.” 
Many of the crustaceans do not swim, but they walk on the 
ground whether in or out of the water. Their course is often 
oblique, and they can use their claws as well in going backwards 
as forwards. 
On the Syrian coast there is a crab, the Ocypoda cursor, which 
