THE PACIFIC OCEAN. 803 



thus lies in ambush for its passing prey. Thus 

 masked, it maintains its assumed cliaracter by the 

 most sluggish movements, as if the little heap were 

 slightly moved by the tide ; but, when taken into 

 the hand, or otherwise alarmed, it can be sufficiently 

 active. The spines upon its body to retain the 

 rubbish, the short but strong claws easily concealed, 

 the eyes placed at the end of long footstalks, curving 

 upwards and thus raised above the mass, show 

 beautiful adaptations of its structure to its economy. 



Another crab of the reef {Calai^pa tuherculata) 

 makes use of another artifice for concealment. It is 

 heart-shaped, with the margin of its shell projecting 

 broadly. When alarmed, it draws its feet under the 

 margin, and folds them close to its side, claps its 

 broad flat claws upon its head, and lies motionless, 

 in which state it may be handled without manifesting 

 any sign of life. A sailor seeing one of these little 

 crabs on the shore, picked it up, and after admiring 

 it awhile, put it into his pocket as a "curious stone;" 

 he was presently astonished by the efforts of his prize 

 to escape from durance vile. 



On the barrier reefs are found elegant animal- 

 flowers (Diazona) expanding their numerous tenta- 

 cles of pink and white, which form a wide circular 

 disk, at the summit of a round fleshy stem. If 

 touched, or otherwise alarmed, they rapidly fold in- 

 wards their beautiful tentacles, and sink to the rock, 

 contracting to a very diminutive size, so as easily 

 to elude observation. The same reefs are enlivened 

 also by numbers of another species of Sea-anemone 

 {Zoantkus), which cover large surfaces of tne rock, 



X 2 



