10 AMONG THE SEA-URCHINS. 



scallop dredge, but in one boating excursion, half way towards the 

 Calf, we found a nice cave, which, as it was low water, we were 

 enabled to enter and watch some of the finny inhabitants disport- 

 ing themselves among the sea-weed. Thus we spent a pleasant 

 hour, resting and watching the treasures of marine life here 

 unfolded to our gaze, for the calmness of the water enabled us to 

 see down to a considerable depth. On the sea-weeds bending 

 under their weight, as well as on the rocks, were numbers of Sea- 

 Urchins, travelling along by the aid of their sucker-feet and 

 pedicellaria, for we had here evidence of the truth of Professor 

 Romanes' suo-aestion as to the use of these latter. We saw one 

 of them distinctly move from one large piece of sea-weed to 

 another by the aid of these organs. Here were also Dead Men's 

 Fingers {Alcyonium di-gitatian), large lobed pieces, bigger than a 

 man's fist, pink, white, and orange colour, with their lovely 

 tentacles fully extended, giving a most delicate and beautiful 

 appearance, little deserving the ill-omened name bestowed upon 

 them by the fishermen, who often bring them up in their nets. 



The shape of the common Sea Urchin, with its armour-like 

 covering and sharp spines, is well known, but surely there must be 

 a good deal of interest in the construction of a creature about 

 which the eloquent historian of the British star-fishes ventures to 

 assert that " the skill of the great Architect of Nature is not less 

 displayed in the construction of a sea-urchin than in the building 

 up of a world." * 



Taking up one of these hard shelly boxes, the superficial 

 observer would naturally come to the conclusion that it is made 

 all of one piece, formed by deposition of lime, like the shell of a 

 mollusc, but if so, we are met with a puzzle more difficult to 

 account for than the milk in the cocoa-nut, as to how the animal 

 enclosed within is enabled to grow in size, for grow they do, as 

 every gradation in size amongst our specimens proves. Minute 

 inspection, however, shows that the shell is composed of 

 hexagonal plates, more than 500 in number, all dove-tailed 

 together with the neatest exactness, the whole outside shell being 

 enveloped by a very thin muscular coat of living flesh, the endo- 

 derm of which secretes the calcareous matter formed round each 



* Forbes' " British Star Fishes," page 153. 



