THE STAR-FISH. 673 



a hexagonal or pentagonal shape, with a slight curve, and having most- 

 ly two opposite sides much longer than the others. As the animal 

 grows fresh deposits of chalky matter are made upon the edges of each 

 plate, so that the plate increases regularly in size, still keeping its 

 shape, and in consequence the dimensions of the whole shell increase, 

 while the globular shape is preserved. If a fresh and perfect specimen 

 be examined, the surface is seen to be covered with short sharp spines 

 set so thickly that the substance of the shell can hardly be seen through 

 them. The structure of these spines is very remarkable, and under the 

 microscope they present some most interesting details. Moreover, each 

 spine is movable at the will of the owner, and works upon a true ball- 

 and-socket joint, the ball being a round globular projection on the sur- 

 face of the shell, and the socket sunk into the base of the spine. 



The common Sea-urchin is edible, and in some places is extensively 

 consumed, fully earning its title of Sea-egg by being boiled and eaten 

 in the same manner as the eggs of poultry. 



Leaving the Echini, we pass to the next large group of Echinoder- 

 mata, called scientifically Asteriadse, and popularly known as Star- 

 fishes. These creatures exhibit in 

 the strongest manner the radiate form 

 of body, the various organs boldly ra- 

 diating from a common centre. 



Many of these creatures are exceed- 

 ingly common upon our own coasts — 

 so plentiful, indeed, as to be intensely 

 hated by the fishermen. Of these, the 

 common Five-finger, or Cross-fish, 

 is perhaps found in the greatest num- 

 bers. All Star-fishes are very wonder- 

 ful beings, and well repay a close and 

 lengthened examination of their habits, The Star-fish {Uraster mbens). 

 their development, and their anatomy. There are sufficient materials 

 in a single Star-fish to fill a whole book as large as the present volume, 

 and it is therefore necessary that our descriptions shall be but brief 

 and compressed. To begin with the ordinary habits of this creature: 

 Every one who has wandered by the seaside has seen a specimen of the 

 common Five-finger thrown on the beach, and perhaps may have passed 

 it by as something too commonplace to deserve notice. If it be taken 

 up, it dangles helplessly from the hand, and appears to be one of the 

 most innocuous beings on the face of the earth. Yet this very creature 

 has in all probability killed and devoured great numbers of the edible 

 molluscs, and has either entirely or partially excited the anger of many 

 an industrious fisherman. 



To begin with the former delinquency: It is found that the Star-fish 



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