86 A HISTORY OF RECENT CRUSTACEA 
shelled, slow-moving Cancridz. On wind-swept stretches 
of sandy beach, and coloured like the sand, they some- 
times seem rather to be borne on the wings of the wind 
than to run. Also with their compressed lancet-like 
fingers they are extremely dexterous in digging into the 
sand. They burrow holes an ell deep, generally perpen- 
dicular, and from these they wander far, when the tide is 
out, in search of food. Krauss observed in South Africa 
the species Ocypode ceratophthalmus (Pallas), and others. 
and he says that while they are busy hunting, every now 
and then they look carefully round, raising their stalked- 
eyes upright, and standing on tiptoe. At the slightest 
movement towards them they run with uncommon rapidity 
to the nearest hole, or, if the danger is too close, press 
themselves flat on the sand, till an attempt is made to 
seize them, and then off they dart. In running they carry 
their bodies high, doubling and dodging with such speed 
and cunning that it is a difficult matter to lay hold of 
them. When the tide comes up, they are enclosed in 
their flooded burrows, and as soon as the waves retreat, 
they are busily employed in clearing them, shovelling out 
the wet sand and heaping it at some little distance off. 
The American species, Ocypode arenaria (Catesby), is de- 
scribed by Professor 8S. I. Smith as having precisely similar 
habits. According to his observation it lives largely upon 
the Amphipods of the genus T'alorchestia, known as 
‘ beach-fleas,’ which inhabit the same localities. ‘It will 
lie in wait,’ he says, ‘and suddenly spring upon them, very 
much as a cat catches mice. It also feeds upon dead fishes 
and other animals that are thrown on the shore by the 
waves.’ 
It is of this species, under the synonym of Ocypoda 
rhombea, Fabricius, that Fritz Miiller speaks in his memor- 
able work ‘ For Darwin.’ ‘In the swift-footed Sand-crabs 
(Ocypoda),’ he says, ‘ —which are exclusively land animals, 
that can scarcely live in water for a single day, and which 
in far less time than that are reduced to a state of com- 
plete collapse in which all voluntary movements cease— 
there has long been known a peculiar arrangement con- 
