86 A HISTORY OF RECENT CRUSTACEA 



shelled, slow-moving Cancridas. 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 S. I. Smith as having precisely similar 

 liabits. According to his observation it lives largely upon 

 the Amphipods of the genus Talorchestia, 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 Oeypoda 

 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. 



