COMMON SEA-UttCHIN. .Ecfcinu 



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

 scope 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 rounc" 

 globular projection on the surface of the shell, and the socket sunk into the base of the 

 spine. When the creature is dead and dried, the membrane which binds together the 

 ball-and-socket joint becomes very fragile, so that at a slight touch the membrane is 

 broken and the spines fall off. The beautiful specimen from which the drawing is taker 

 is in the possession of Mr. Sowerby, and is remarkable for the fact that the spines are al 

 perfect and in their place. 



Other peculiarities of structure will be noted in connexion with the different species. 



The Common Sea-urchin is edible, and in some places is extensively consumed, full] 

 earning its title of Sea-egg, by being boiled and eaten in the same manner as the eggs of 

 poultry. 



The fishing for these creatures in the Bay of Naples is graphically and quaintly 

 described by Mr. E. Jones: "I had not swum very far from the beach before I founc 

 myself surrounded by some fifty or sixty human heads, the bodies belonging to whicl 

 were invisible, and interspersed among these, perhaps, an equal number of pairs of fee 

 sticking out of the water. As I approached the spot, the entire scene became sufficient!] 

 ludicrous and bewildering. . . . Down went a head, up came a pair of heels do\ 

 went a pair of heels, up came a head ; and as something like a hundred people were 

 diligently practising the same manoeuvre, the strange vicissitude from heels to head and 

 head to heels, going on simultaneously, was rather a puzzling spectacle." 



