THE FEEDING HABITS OF THE SEA-URCHIN. 99 



6. The Time Spent in Feeding. 



The length of time a Sea-Urchin will remain in one place 

 to consume food has several times been incidentally mentioned. 

 Four large individuals remained in a bunch of seaweed for two 

 weeks, at the end of which time it was reduced to a loose heap 

 of fajcal pellets ; and five Sea-Urchins remained in another 

 bunch for over three weeks. Three Sea-Urchins " sat " on a 

 large dead Common Hermit-Crab from 10 a.m. on August 16th 

 until 10 a.m. on the 19th, when, owing to its decayed state, 

 the crustacean had to be removed from the water. A Sea- 

 Urchin of 10 mm. remained in one place to eat the ray of a 

 Sun- Star for two whole days, and another one sat on a living 

 inverted Periwinkle for thirty hours. The Sea-Urchin of 19 mm., 

 which ate part of the chalk, mentioned on p. 91, remained on 

 the chalk for nineteen hours. 



