THE FEEDING HABITS OF THE SEA-URCHIN. 83 



struggle. The Sea-Urchin held it tightly by pressing a number 

 of spines not only around but also upon the body of the fish, 

 those spines which were pressed on the prey being used with 

 such effect that they made deep indentations in its body. The 

 Sea-Urchin now raised one part of its body from the side of the 

 tank, and with spines and tube-feet gradually urged its prey 

 towards the mouth, the fish, in spite of several efforts, being 

 unable to get free. As soon as the prey had been brought into 

 Buch a position beneath the mouth that the teeth could con- 

 veniently work upon it, the Sea-Urchin attached a number of 

 tube-feet to, and also pressed spines upon, the side of the tank 

 in such a way that the victim was imprisoned as in a cage. The 

 Sea-Urchin remained for several hours upon the Wrasse, of 

 which it ate about a third part, afterwards allowing the remainder 

 to fall to the bottom of the aquarium. 



Arthropoda. — Eichelbaum found remains of crustaceans in 

 each of his eleven examples. These remains consisted of legs, 

 antennae, etc., fragments of small crabs, and also copepods and 

 a questionable Gammarus. 



One of the Sea-Urchins studied by me climbed on to a 

 living Top {Trochus zizypMnus) , which bore several living Acorn- 

 Barnacles {Balanus balanoides), broke up the shells, and then ate 

 the soft parts of the cirripedes. A large dead CommonHermit-Crab 

 {Eupagurus 6e?'n/iarrfi(s), which was placed in an aquarium contain- 

 ing twelve Sea-Urchins, was soon attacked by four of the echi- 

 noids ; they ate the whole of the Hermit-Crab's abdomen (including 

 the limbs), three of the walking legs (the great claws not being 

 touched), most of the carapace and contents of the thorax, and 

 the antennae of one side. A large male Long-legged Spider- 

 Crab {Stenorhynchus phalangium) died during the night, and 

 before the morning was partly eaten by a large Sea-Urchin, 

 which completely devoured the small abdomen of the crustacean, 

 and scraped away the surface layer of a considerable area of 

 the under surface of the thorax. Two of the great claws of a 

 Common Spider-Crab {Hyas araneus) were given to two large 

 Sea-Urchins, and in both cases they were almost wholly eaten. 

 Six walking-legs of the Common Spider-Crab and two of the 

 walking-legs of the Shore-Crab {Carcinus mamas) were on one 

 occasion distributed amongst eight large Sea-Urchins, and were 



